United States
Environmental Protection
Agency
Air and Radiation
(ANR-460)
EPA-400-R-92-001
May 1992
Manual of
Protective Action Guides
And Protective Actions
For Nuclear Incidents
Internet Address (URL) • http://www.epa.gov
Recycled/Recyclable • Printed with Vegetable Oil Based Inks
on Recycled Paper (Minimum 50% Postconsumer)
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FOREWOED
Public officials are charged with the responsibility to protect the health of
the public during hazardous incidents. The purpose of this manual is to assist
these officials in establishing emergency response plans and in making decisions
during a nuclear incident. It provides radiological protection guidance that may
be used for responding to any type of nuclear incident or radiological emergency,
except nuclear war.
Under regulations governing radiological emergency planning and
preparedness issued by the Federal Emergency Management Agency (47 FR
10758, March 11, 1982), the Environmental Protection Agency's responsibilities
include, among others, (1) establishing Protective Action Guides (PAGs), (2)
preparing guidance on implementing PAGs, including recommendations on
protective actions, (3) developing and promulgating guidance to State and local
governments on the preparation of emergency response plans, and (4) developing,
implementing, and presenting training programs for State and local officials on
PAGs and protective actions, radiation dose assessment, and decision making.
This document is intended to respond to the first two responsibilities.
The manual begins with a general discussion of Protective Action Guides
(PAGs) and their use in planning for protective actions to safeguard public health.
It then presents PAGs for specific exposure pathways and associated time periods.
These PAGs apply to all types of nuclear incidents. This is followed by guidance
for the implementation of PAGs. Finally, appendices provide definitions,
background information on health risks, and other information supporting the
choice of the numerical values of the PAGs.
PAGs for protection from an airborne plume during the early phase of an
incident at a nuclear power plant were published in the 1980 edition of this
manual. These have now been revised to apply to a much broader range of
situations and replace the PAGs formerly published in Chapters 2 and 5.
Recommendations and background information for protection from ingestion of
contaminated food were published by the Food and Drug Administration in 1982.
These are reprinted here as Chapter 3 and Appendix D. Recommendations for
PAGs for relocation are presented in Chapters 4 and 7. Additional radiation
protection guidance for recovery will be developed at a later date. We are
continuing work to develop PAGs for drinking water and, in cooperation with
FDA, revised PAGs for food. When experience has been gained in the application
of these PAGs, they will be reexamined and refined as necessary, proposed for
review, and then recommended to the President as Federal radiation protection
guidance.
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This manual is being re-published to consolidate existing recommendations
in a single volume. As revised and additional recommendations are developed,
they will be issued as revisions to this manual. These revised PAGs are
appropriate for incorporation into emergency response plans when they are revised
or when new plans are developed. However, it is important to recognize that
regulatory requirements for emergency response are not provided by this manual;
they are established by the cognizant agency (e.g., the Nuclear Regulatory
Commission in the case of commercial nuclear reactors, or the Department of
Energy in the case of their contractor-operated nuclear facilities).
Users of this manual are encouraged to provide comments and suggestions
for improving its contents. Comments should be sent to Allan C. B. Richardson,
Criteria and Standards Division (ANR-460), Office of Radiation Programs, U.S.
Environmental Protection Agency, Washington, DC 20460.
Washington, D.C.
_ T. Oge
Director, Office of
Radiation Programs
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CONTENTS
Page
Foreword . . . . iii
1. Overview 1-1
1.0 Introduction 1-1
1.1 Nuclear Incident Phases and Protective Actions 1-2
1.2 Basis for Selecting PAGs . . 1-5
1.3 Planning . . . . 1-6
1.4 Implementation of Protective Action 1-6
References 1-7
2. Protective Action Guides for the Early Phase of an Atmospheric Release 2-1
2.1 Introduction 2-1
2.1.1 Applicability 2-1
2.1.2 Emergency Planning Zones and the PAGs 2-2
2.1.3 Incident Phase 2-3
2.2 Exposure Pathways 2-3
2.3 The Protective Action Guides 2-4
2.3.1 Evacuation and Sheltering 2-5
2.3.2 Thyroid and Skin Protection 2-7
2.4 Dose Projection 2-8
2.5 Guidance for Controlling Doses to Workers Under
Emergency Conditions 2-9
References 2-13
3. Protective Action Guides for the Intermediate Phase (Food and Water) 3-1
4. Protective Action Guides for the Intermediate Phase
(Deposited Radioactive Materials) 4-1
4.1 Introduction . 4-1
4.1.1 Exposure Pathways 4-2
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Page
4.1.2 The Population Affected , ... 4-3
4.2 The Protective Action Guides for Deposited Radioactivity 4-3
4.2.1 Longer Term Objectives of the Protective Action Guides . . . 4-4
4.2.2 Applying the Protective Action Guides for Relocation 4-5
4.3 Exposure Limits for Persons Reentering the Restricted Zone .... 4-6
References 4-6
5. Implementing the Protective Action Guides for the Early Phase 5-1
5.1 Introduction , 5-1
5.2 Initial Response and Sequence of Subsequent Actions 5-1
5.2.1 Notification , 5-3
5.2.2 Immediate Protective Action 5-3
5.3 The Establishment of Exposure Patterns 5-4
5.4 Dose Projection 5-6
5.4.1 Duration of Exposure 5-6
5.4.2 Dose Conversion Factors 5-8
5.4.3 Comparison with Previously-Recommended PAGs 5-16
5.5 Protective Actions 5-17
5.5.1 Evacuation 5-18
5.5.2 Sheltering 5-19
5.5.3 General Guidance for Evacuation and Sheltering 5-21
5.6 Procedures for Calculating Dose Conversion Factors 5-22
5.6.1 External Exposure to Gamma Radiation from the Plume . 5-23
5.6.2 Inhalation from the Plume 5-23
5.6.3 External Dose from Deposited Materials 5-24
References 5-42
VI
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6, Implementing the Protective Action Guides for the Intermediate Phase
(Food and Water) 6-1
7. Implementing the Protective Action Guides for the Intermediate Phase
(Exposure to Deposited Materials) 7-1
7.1 Introduction 7-1
7.1.1 Protective Actions 7-2
7.1.2 Areas Involved 7-2
7.1.3 Sequence of Events 7-4
7.2 Establishment of Isodose-Rate Lines 7-6
7.3 Dose Projection 7-7
?.f
* •"
7.3.1 Projected External Gamma Dose 7-8
7.3.2 Inhalation Dose Projection ; . 7-14
7.4 Priorities 7-17
7.5 Reentry , 7-17
7.6 Surface Contamination Control 7-19
7.6.1 Considerations and Constraints 7-19
7.6.2 Numerical Relationships 7-21
7.6,3 Recommended Surface Contamination Limits .......... 7-21
References ; 7-25
f
8. Radiation Protection Guidance for the LateTPhase (Recovery) (reserved) 8-1
TABLES
1-1 Exposure Pathways, Accident Phases, and Protective Actions ....... 1-4
2-1 Protective Actions Guides for the Early Phase of a Nuclear Incident . . 2-6
2-2 Guidance on Dose Limits for Workers Performing Emergency Services 2-10
2-3 Health Effects Associated with Whole-Body Absorbed Doses
Received Within a Few Hours (see Appendix B) . . . . 2-12
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2-4 Approximate Cancer Risk to Average Individuals from 25 Rem
Effective Dose Equivalent Delivered Promptly (see Appendix C) .... 2-12
4-1 Protective Action Guides for Exposure to Deposited Radioactivity
During the Intermediate Phase of a Nuclear Incident 4-4
5-1 Dose Conversion Factors (DCP) and Derived Response Levels (DRL)
for Combined Exposure Pathways During the Early Phase of
a Nuclear Incident 5-9
5-2 Dose Conversion Factors (DCF) and Derived Response Levels (DRL)
Corresponding to a 5 rem Thyroid Dose Equivalent from
Inhalation of Radioiodine 5-15
5-3 Dose Conversion Factors (DCF) and Derived Response Levels (DRL)
for External Exposure Due to Immersion in Contaminated Air 5-25
5-4 Dose Conversion Factors (DCF) and Derived Response Levels (DRL)
for Doses Due to Inhalation 5-31
5-5 Dose Conversion Factors (DCF) and Derived Response Levels (DRL)
for a 4-Day Exposure to Gamma Radiation
from Deposited Radionuclides 5-37
7-1 Gamma Exposure Rate and Effective Dose Equivalent (Corrected
for Radioactive Decay and Weathering) due to an Initial Uniform
Concentration of 1 pOi/m2 on Ground Surface 7-9
7-2 Exposure Rate and the Effective Dose Equivalent (Corrected for
Radioactive Decay) due to an Initial Concentration of 1 pCi/m
on Ground Surface . 7-10
7-3 Example Calculation of Dose Conversion Factors for Gamma Exposure
Rate Measurements Based on Measured Isotopic Concentrations .... 7-13
7-4 Dose Conversion Factors for Inhalation of Resuspended Material ... 7-16
7-5 Skin Beta Dose Conversion Factors for Deposited Radionuclides .... 7-25
7-6 Recommended Surface Contamination Screening Levels for
Emergency Screening Levels for Emergency Screening of Persons
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and Other Surfaces at Screening or Monitoring Stations in High
Background Radiation Areas '....' .C. ............ 7-23
7-7 Recommended Surface Contamination Screening Levels for Persons
and Other Surfaces at Monitoring Stations in Low
Background Radiation Areas 7-24
FIGURES
7-1 Response Areas , .... 7-3
7-2 Time Frame of Response to a Major Nuclear Reactor Accident 7-6
APPENDICES
A. Glossary
B. Risks to Health From Radiation Doses that may Result from
Nuclear Incidents
C. Protective Action Guides for the Early Phase: Supporting Information
D. Background for Protective Action Recommendations: Accidental
Contamination of Food and Animal Feeds
E. Protective Action Guides for the Intermediate Phase (Relocation)
Background Information
F. Radiation Protective Criteria for the Late Phase: Supporting
Information (Reserved)
IX
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CHAPTER 1
Overview
1.0 Introduction
Public officials, in discharging their
responsibility to protect the health of
the public during hazardous situations,
will usually be faced with decisions
that must be made in a short period of
time. A number of factors influencing
the choice of protective actions will
exist, so that the decisions may be
complex. Further, all of the
information needed to make the
optimum choice will usually not be
immediately available. In such situ-
ations, it will therefore be helpful if the
complexity of the information upon
which needed decisions are based can
be reduced by careful planning during
the formulation of emergency response
plans.
The U.S. Environmental Protection
Agency has developed this manual to
assist public officials in planning for
emergency response to nuclear
incidents. In the context of this
manual, a nuclear incident is defined
as an event or a series of events, either
deliberate or accidental, leading to the
release, or potential release, into the
environment of radioactive materials in
sufficient quantity to warrant
consideration of protective actions.
(The term "incident" includes accidents,
in the context of this manual.) A
radiological emergency may result from
an incident at a variety of types of
facilities, including, but not limited to,
those that are part of the nuclear fuel
cycle, defense and research facilities,
and facilities that produce or use
radioisotopes, or from an incident
connected with the transportation or
use of radioactive materials at locations
not L classified as "facilities". This
manual provides radiological protection
criteria intended for application to all
nuclear incidents requiring
consideration of protective actions,
other than nuclear war. It is designed
for the use of those in Federal, State,
and local government with
responsibility for emergency response
planning. The manual also provides
guidance for implementation of the
criteria. This has been developed
primarily for incidents at nuclear
power facilities. Although this imple-
mentation guidance is intended to be
useful for application at other facilities
or uses of radioactivity, emergency
response plans will require the
development of additional
implementation procedures when
physical characteristics of the
radionuclides involved are different
from those considered here.
The decision to advise members of
the public to take an action to protect
themselves from radiation from a
nuclear incident involves a complex
judgment in which the risk avoided by
the protective action must be weighed
in the context of the risks involved in
taking the action. Furthermore, the
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decision may have to be made under
emergency conditions, with little or no
detailed information available.
Therefore, considerable planning is
necessary to reduce to a manageable
level the complexity of decisions
required to effectively protect the
public at the time of an incident.
An objective of emergency planning
is to simplify the choice of possible
responses so that judgments are
required only for viable and useful
alternatives when an emergency
occurs. During the planning process it
is possible to make some value
judgments and to determine which
responses are not required, which
decisions can be made on the basis of
prior judgments, and which judgments
must be made during an actual
emergency. From this exercise, it is
then possible to devise operational
plans which can be used to respond to
the spectrum of hazardous situations
which may develop.
The main contribution to the
protection of the public from abnormal
releases of radioactive material is
provided by site selection, design,
quality assurance in construction,
engineered safety systems, and the
competence of staff in safe operation
and maintenance. These measures can
reduce both the probability and the
magnitude of potential consequences of
an accident. Despite these measures,
the occurrence of nuclear incidents
cannot be excluded. Accordingly, emer-
gency response planning to mitigate
the consequences of an incident is a
necessary supplementary level of
protection.
During a nuclear incident, when
the source of exposure of the public is
not under control, the public usually
can be protected only by some form of
intervention which will disrupt normal
living. Such intervention is termed
protective action. A Protective Action
Guide (PAG) is the projected dose to
reference man, or other defined
individual, from an unplanned release
of radioactive material at which a
specific protective action to reduce or
avoid that dose is recommended. The
objective of this manual is to provide
such PAGs for the principal protective
actions available to public officials
during a nuclear incident, and to
provide guidance for their use.
1.1 Nuclear Incident Phases and
Protective Actions
It is convenient to identify three
time phases which are generally
accepted as being common to all
nuclear incident sequences; within
each, different considerations apply to
most protective actions. These are
termed the early, intermediate, and
late phases. Although these phases
cannot be represented by precise
periods and may overlap, they provide
a useful framework for the
considerations involved in emergency
response planning.
The early phase (also referred to as
the emergency phase) is the period at
the beginning of a nuclear incident
when immediate decisions for effective
use of protective actions are required
and must therefore usually be based
primarily on the status of the nuclear
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facility (or other incident site) and the
prognosis for worsening conditions.
When available, predictions of radio-
logical conditions in the environment
based on the condition of the source or
actual environmental measurements
may also be used. Protective actions
based on the PAGs may be preceded by
precautionary actions during this
period. This phase may last from
hours to days.
The intermediate phase is the
period beginning after the source and
releases have been brought under
control and reliable environmental
measurements are available for use as
a for decisions on additional
protective actions. It extends until
these additional protective actions are
terminated. This phase may overlap
the early and late phase and may last
from weeks to many months.
The late phase (also referred to as
the recovery phase) is the period
beginning when recovery action
designed to reduce radiation levels in
the environment to acceptable levels
for unrestricted use are commenced,
and ending when all recovery actions
have been completed. This period may
extend from months to years.
The protective actions available to
avoid or reduce radiation dose can be
categorized as a function of exposure
pathway and incident phase, as shown
in Table 1-1. Evacuation and shel-
tering (supplemented by bathing and
changes of clothing), are the principal
protective actions for use $wdng the
early phase to protect the public from
exposure to direct radiation and
inhalation from an airborne plume. It
may'-also be ^appropriate to initiate
protective actio'n for the milk supply
during this period, and, in cases where
emergency response plans include
procedures for issuing stable iodine to
reduce thyroid dose (PE-85), this may
be an appropriate protective action for
the early phase.
Some protective actions are not
addressed by assignment of a PAG.
For example, the control of access to
areas is a protective action whose
introduction, is coupled to a decision to
implement one of the other early or
intermediate phase protective actions
and does not have a separate PAG.
And, although the use of simple, ad hoc
respiratory protection may be
applicable for supplementary protection
in some circumstances, this protective
action is primarily for use by
emergency workers.
There are two types of protective
actions during the intermediate phase.
First, relocation and decontamination
are the principal protective actions for
protection of the public from whole
body external exposure due to
deposited material and from inhalation
of any resuspended radioactive
particulate materials during the
intermediate and late phases, , It is
assumed that decisions will be made
during the intermediate phase
concerning whether areas from which
the public has been relocated will be
decontaminated and reoccupied, or
condemned and the occupants
permanently relocated. The second
major type of protective action during
the intermediate phase encompasses
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TABLE 1-1. EXPOSURE PATHWAYS, INCIDENT PHASES,
AND PROTECTIVE ACTIONS.
POTENTIAL EXPOSURE PATHWAYS
AND INCIDENT PHASES
PROTECTIVE
ACTIONS
1, External radiation from
facility
2. External radiation from plume
3. Inhalation of activity in
plume
4. Contamination of skin and
clothes
5. External radiation from
ground deposition of activity
6. Ingestion of contaminated
food and water
7. Inhalation of resuspended
activity
Early
Intermediate
Late
Sheltering
Evacuation
Control of access
Sheltering
Evacuation
Control of access
Sheltering
Administration of stable iodine
Evacuation
Control of access
Sheltering
Evacuation
Decontamination of persons
Evacuation
Relocation
Decontamination of land
and property
Food and water controls
Relocation
Decontamination of land
and property
Note: The use of stored animal feed and uncontaminated water to limit the uptake of radionuclides
by domestic animals in the food chain can be applicable in any of the phases.
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restrictions on the use of contaminated
food and water. This protective action,
in particular, may overlap the early
and late phases.
It is necessary to distinguish
between evacuation and relocation with
regard to incident phases. Evacuation
is the urgent removal of people from an
area to avoid or reduce high-level,
short-term exposure, usually from the
plume or deposited activity.
Relocation, on the other hand, is the
removal or continued exclusion of
people (households) from contaminated
areas to avoid chronic radiation
exposure. Conditions may develop in
which some groups who have been
evacuated in an emergency may be
allowed to return based on the
relocation PAGs, while others may be
converted to relocation status.
1.2 Basis for Selecting Protective
Action Guides
The PAGs in this manual
incorporate the concepts and guidance
contained in Federal Radiation Council
(FRC) Reports 5 and 7 (FR-64 and
FR-65). One of these is that the
decision to implement protective
actions should be based on the
projected dose that would be received if
the protective actions were not
implemented. However, since these
reports were issued, considerable
additional guidance has been developed
on the subject of emergency response
(IC-84, IA-89). EPA considered the
following four principles in establishing
values for the PAGs:
1. Acute effects on health (those that
would be observable within a short
period of time and which have a dose
threshold below which such effects are
not likely to occur) should be avoided.
2. The risk of. delayed effects on
health (primarily cancer and genetic
effects for which linear nonthreshold
relationships to dose are, assumed)
should not exceed upper bounds that
are judged to be adequately protective
of public health under emergency
conditions, and are reasonably
achievable.
3. PAGs should not be higher than
justified on the basis of optimization of
cost and the collective risk of effects on
health. That is, any reduction of risk
to public health achievable at
acceptable cost should be carried out.
4. Regardless of the above principles,
the risk to health from a protective
action should not itself exceed the risk
to health from the dose that would be
avoided.
The above principles apply to the
selection of any PAG. Principles 1, 3,
and 4 have been proposed for use by
the international community as
essential bases for decisions to
intervene during an incident and
Principle 2 has been recognized as an
appropriate additional consideration
(IA-89). Appendices C and E apply
these principles to the choice of PAGs
for evacuation and relocation.
Although in establishing the PAGs it is
prudent to consider a range of source
terms to assess the costs associated
with their implementation, the PAGs
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are chosen so as to be independent of
the magnitude or type of release.
1.3 Planning
The planning elements for
developing radiological emergency
response plans for nuclear incidents at
commercial nuclear power facilities are
provided in a separate document,
NUEEG-0654 (NR-80), which
references the PAGs in this Manual as
the basis for emergency response.
Planning elements for other types of
nuclear incidents should be developed
using similar types of considerations.
Similarly, guidance for nuclear
power facilities on time frames for
response, the types of releases to be
considered, emergency planning zones
(EPZ), and the potential effectiveness
of various protective actions is provided
in NUREG-0396 (NR-78). The size and
shape of the recommended EPZs were
only partially based on consideration of
the numerical values of the PAGs. A
principle additional basis was that the
planning zone for evacuation and
sheltering should be large enough to
accommodate any urban and rural
areas affected and involve the various
organizations needed for emergency
response. This consideration is
appropriate for any facility requiring
an emergency response plan involving
offsite areas. Experience gained
through emergency response exercises
is then expected to provide an adequate
basis for expanding the response to an
actual incident to larger areas, if
needed. It is also noted that the
10-mile radius EPZ for the early phase
is large enough to avoid exceeding the
PAGs for the early phase at its
boundary for low-consequence, nuclear
reactor, core-melt accidents and to
avoid early fatalities for
high-consequence, nuclear reactor
core-melt accidents. The 50-mile EPZ
for ingestion pathways was selected to
account for the proportionately higher
doses via ingestion compared to
inhalation and whole body external
exposure pathways.
1,4 Implementation of Protective
Actions
The sequence of events during the
early phase includes evaluation of
conditions at the location of the
incident, notification of responsible
authorities, prediction or evaluation of
potential consequences to the general
public, recommendations for action,
and implementing protection of the
public. In the early phase of response,
the time available to implement the
most effective protective actions maybe
limited.
Immediately upon becoming aware
that an incident has occurred that may
result in exposure of the population,
responsible authorities should make a
preliminary evaluation to determine
the nature and potential magnitude of
the incident. This evaluation should
determine whether conditions indicate
a significant possibility of a major
release and, to the extent feasible,
determine potential exposure
pathways, populations at risk, and
projected doses. The incident eval-
uation and recommendations should
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then be presented to emergency
response authorities for action. In the
absence of recommendations for
protective actions in specific areas from
the official responsible for the source,
the emergency plan should, where
practicable, provide for protective
action in predesignated areas.
Contrary to the usual situation
during the early phase, dose projections
used to support protective action
decisions during the intermediate and
late phases will be based on
measurements of environmental
radioactivity and dose models.
Following relocation of the public from
affected areas to protect them from
exposure to deposited materials, it will
also be necessary to compile
radiological and cost of
decontamination data to form the basis
for radiation protection decisions for
recovery.
The PAGs do not imply an
acceptable level of risk for normal
(nonemergeney conditions). They also
do not represent the boundary between
safe and unsafe conditions, rather, they
are the approximate levels at which the
associated protective actions are
justified. Furthermore, under emer-
gency conditions, in addition to the
protective actions specifically identified
for application of PAGs, any other
reasonable measures available should
be taken to minimize radiation
exposure of the general public and of
emergency workers.
References
FE-85 Federal Emergency
Management Agency. Federal Policy on
Distribution of Potassium Iodide around
Nuclear Power Sites for Use as a Thyroidal
Blocking Agent. Federal Register. 50.30256;
July 24, 1985.
FR-64 Federal Radiation
Council. Radiation Protection Guidance for
Federal Agencies. Federal Register. 29.
12056-7; August 22, 1965.
FR-65 Federal Radiation
Council. Radiation Protection Guidance for
Federal Agencies. Federal Register, 30.
6953-5; May 22, 1965.
IA-89 International Atomic
Energy Agency. Principles for Establishing
Intervention Levels for the Protection of the
Public in the Event of a Nuclear Accident or
Radiological Emergency. Safety Series No.
72, revision 1, International Atomic Energy
Agency, Vienna (1991).
IC-84 International
Commission on Radiological Protection.
Protection of the Public in the Event of
Major Radiation Accidents: Principles for
Planning, ICRP Publication 40, Pergamon
Press, Oxford (1984).
NR-78 Nuclear Regulatory
Commission. Planning Basis for the
Development of State and Local Government
Radiological Emergency Response Plans in
Support of Light Water Nuclear Power
Plants, U.S. Nuclear Regulatory
Commission, Washington (1978).
NR-80 Nuclear Regulatory
Commission. Criteria for Preparation and
Evaluation of Radiological Emergency
Response Plans and Preparedness in Support
of Nuclear Power Plants. U.S. Nuclear
Regulatory Commission, Washington (1980).
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CHAPTER 2
Protective Action. Guides for the Early Phase
of an. Atmospheric Release
2.1 Introduction
Rapid action may be needed to
protect members of the public during
an incident involving a large release of
radioactive materials to the
atmosphere. This chapter identifies
the levels of exposure to radiation at
which such prompt protective action
should be initiated. These are set forth
as Protective Action Guides (PAGs) for
the general population. Guidance for
limiting exposure of workers during
such an incident is also provided. This
guidance applies to any type of nuclear
accident or other incident (except
nuclear war) that can result in
exposure of the public to an airborne
release of radioactive materials.
In the case of an airborne release
the principal relevant protective
actions are evacuation or sheltering.
These may be supplemented by
additional actions such as washing and
changing clothing or by using stable
iodine to partially block uptake of
radioiodine by the thyroid.
The former Federal Radiation
Council (FRC), in a series of
recommendations issued in the 1960's,
introduced the concept of PAGs and
issued guides for avoidance of exposure
due to ingestion of strontium-89,
strontium-90, eesium-137, and
iodme-131. Those guides were
developed for the case of worldwide
atmospheric fallout from weapons
testing, and are appropriate for
application to intake due to long term
contamination from such atmospheric
releases. That is, they were not
developed for protective actions
relevant to prompt exposure to an
airborne release from a fixed facility.
The guidance in this chapter thus does
not supersede this previous FRC
guidance, but provides new guidance
for different exposure pathways and
situations.
2.1.1 Applicability
These PAGs are expected to be
used for planning purposes: for
example, to develop radiological
emergency response plans and to
exercise those plans. They provide
guidance for i response decisions and
should not be regarded as dose limits.
During a real incident, because of
characteristics of the incident and local
conditions that cannot be anticipated,
professional judgment will be required
in their application. Situations could
occur, for example, in which a nuclear
incident happens when environmental
conditions or!other constraints make
evacuation impracticable. In these
situations, sheltering may be the
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protective action of choice, even at
projected doses above the PAG for
evacuation. Conversely, in some cases
evacuation may be useful at projected
doses below the PAGs. Each case will
require judgments by those responsible
for decisions on protective actions at
the time of an incident.
The PAGs are intended for general
use to protect all of the individuals in
an exposed population. To avoid social
and family disruption and the
complexity of implementing different
PAGs for different groups under
emergency conditions, the PAGs should
be applied equally to most members of
the population. However, there are
some population groups that are at
markedly different levels of risk from
some protective actions ~ particularly
evacuation. Evacuation at higher
values is appropriate for a few groups
for whom the risk associated with
evacuation is exceptionally high (e.g.,
the infirm who are not readily mobile),
and the PAGs provide for this.
Some incidents may occur under
circumstances in which protective
actions cannot be implemented prior to
a release (e.g., transportation
incidents). Other incidents may
involve only slow, small releases over
an extended period, so that the urgency
is reduced and protective action maybe
more appropriately treated as
relocation (see Chapter 4) than as
evacuation. Careful judgment will be
needed to decide whether or not to
apply these PAGs for the early phase
under such circumstances.
The PAGs do not imply an
acceptable level of risk for normal
(nonemergency) conditions. PAGs also
do not represent the boundary between
safe and unsafe conditions; rather, they
are the approximate levels at which the
associated protective actions are
justified. Furthermore, under
emergency conditions, in addition to
the protective actions specifically
identified, any other reasonable
measures available should be taken to
reduce radiation exposure of the
general public and of emergency
workers. These PAGs are not intended
for use as criteria for the ingestion of
contaminated food or water, for
relocation, or for return to an area
contaminated by radioactivity.
Separate guidance is provided for these
situations in Chapters 3 and 4.
2.1.2 Emergency Planning Zones and
the PAGs
For the purpose of identifying the
size of the planning area needed to
establish and test radiological
emergency response plans, emergency
planning zones (EPZs) are typically
specified around nuclear facilities.
There has been some confusion among
emergency planners between these
EPZs and the areas potentially affected
by protective actions. It is not
appropriate to use the maximum
distance where a PAG might be
exceeded as the basis for establishing
the boundary of the EPZ for a facility.
For example, the choice of EPZs for
commercial nuclear power facilities has
been based, primarily, on consideration
of the area needed to assure an
2-2
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adequate planning basis for local
response functions and the area in
which acute health effects could occur.1
These considerations will also be
appropriate for use in selecting EPZs
for most other nuclear facilities.
However, since it will usually not be
necessary to have offsite planning if
PAGs cannot be exceeded offsite, EPZs
need not be established for such cases.
2,1.3 Incident Phase
The period addressed by this
chapter is denoted the "early phase."
This is somewhat arbitrarily defined as
the period beginning at the projected
(or actual) initiation of a release and
extending to a few days later, when
deposition of airborne materials has
ceased and enough information has
become available to permit reliable
decisions about the need for longer
term protection.. During the early
phase of an incident doses may accrue
both from airborne and from deposited
radioactive materials. Since the dose
to persons who are not evacuated will
continue until relocation can be
implemented (if it is necessary), it is
appropriate to include in the early
The development of EPZs for nuclear power
facilities is discussed in the 1978 NRG/EPA
document "Planning Basis for the Development
of State and Local Government Radiological
Emergency Response Plans in Support of Light
Water Nuclear Power Plants" NUREG-0396.
EPZs for these facilities have typically been
chosen to have a radius of approximately 10
miles for planning evacuation and sheltering
and a radius of approximately 50 miles for
planning protection from ingestion of
contaminated foods.
phase the total dose that will be
received prior! to such relocation. For
the purpose of planning, it will usually
be convenient to assume that the early
phase will last for four days -- that is,
that the duration of the primary
release is less than four days, and that
exposure to deposited materials after
four days can be addressed through
other protective actions, such as
relocation, if this is warranted.
(Because of the unique characteristics
of some facilities or situations, different
time periods may be more appropriate
for planning purposes, with
corresponding modification of the dose
conversion factors cited in Chapter 5.)
2,2 Exposure Pathways
The PAGs for members of the
public specified in this chapter refer
only to doses incurred during the early
phase. These may include external
gamma dose and beta dose to the skin
from direct exposure to airborne
materials and from deposited
materials, and the committed dose to
internal organs from inhalation of
radioactive material. Exposure
pathways that make only a small
contribution, (e.g., less than about 10
percent) to the dose incurred in the
early phase need not be considered.
Inhalation of resuspended particulate
materials will* for example, generally
fall into this category.
Individuals exposed to a plume
may also be exposed to deposited
material over longer periods of time via
ingestion, direct external exposure, and
inhalation pathways. Because it is
2-3
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usually not practicable, at the time of
an incident, to project these long-term
doses and because different protective
actions maybe appropriate, these doses
are not included in the dose specified
in the PAGs for the early phase. Such
doses are addressed by the PAGs for
the intermediate phase (see Chapters 3
and 4).
The first exposure pathway from
an accidental airborne release of
radioactive material will often be direct
exposure to an overhead plume of
radioactive material carried by winds.
The detailed content of such a plume
will depend on the source involved and
conditions of the incident. For
example, in the case of an incident at a
nuclear power reactor, it would most
commonly contain radioactive noble
gases, but may also contain
radioiodines and radioactive particulate
materials. Many of the these materials
emit gamma radiation which can
expose people nearby, as the plume
passes. In the case of some other types
of incidents, particularly those
involving releases of alpha emitting
particulate materials, direct exposure
to gamma radiation is not likely to be
the most important pathway.
A second exposure pathway occurs
when people are directly immersed in a
radioactive plume, in which case
radioactive material is inhaled (and the
skin and clothes may also become
contaminated), e.g., when particulate
materials or radioiodines are present.
When this occurs, internal body organs
as well as the skin may be exposed.
Although exposure from materials
deposited on the skin and clothing
could be significant, generally it will be
less important than that from
radioactive material taken into the
body through inhalation. This is
especially true if early protective
actions include washing exposed skin
and changing clothing. Inhaled
radioactive particulate materials,
depending on their solubility in body
fluids, may remain in the lungs or
move via the bloodstream to other
organs, prior to elimination from the
body. Some radiormelides, once in the
bloodstream, are concentrated in a
single body organ, with only small
amounts going to other organs. For
example, if radioiodines are inhaled; a
significant fraction moves rapidly
through the bloodstream to the thyroid
gland.
As the passage of a radioactive
plume containing particulate material
and/or radioiodine progresses, some of
these materials will deposit onto the
ground and other surfaces and create a
third exposure pathway. People
present after the plume has passed will
receive exposure from gamma and beta
radiation emitted from these deposited
materials. If large quantities of
radioiodines or gamma-emitting
particulate materials are contained in
a release, this exposure pathway, over
a long period, can be more significant
than direct exposure to gamma
radiation from the passing plume.
2.3 The Protective Action Guides
The PAGs for response during the
early phase of an incident are
summarized in Table 2-1. The PAG for
2-4
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evacuation (or, as an alternative in
certain cases, sheltering) is expressed
in terms of the projected sum of the
effective dose equivalent from external
radiation and the committed effective
dose equivalent incurred from
inhalation of radioactive materials from
exposure and intake during the early
phase. (Further references to dose to
members of the public in this Chapter
refer to this definition, unless
otherwise specified.) Supplementary
guides are specified in terms of
committed dose equivalent to the
thyroid and dose equivalent to the skin.
The PAG for the administration of
stable iodine is specified in terms of the
committed dose equivalent to the
thyroid from radioiodine. This more
complete guidance updates and
replaces previous values, expressed in
terms of whole-body dose equivalent
from external gamma exposure and
thyroid dose equivalent from inhalation
of radioactive iodines, that were
recommended in the 1980 edition of
this document.
2.3.1 Evacuation and Sheltering
The basis for the PAGs is given in
Appendix C. In summary, this analysis
indicates that evacuation of the public
will usually be justified when the
projected dose to an individual is one
rem. This conclusion is based prim-
arily on EPA's judgment concerning
acceptable levels of risk of effects on
public health from radiation exposure
in an emergency situation. The
analysis also shows that, at this
radiation dose, the risk avoided is
usually much greater than the risk
from evacuation itself. However, EPA
recognizes the'uncertainties associated
with quantifying risks associated with
these levels of radiation exposure, as
well as the variability of risks
associated with evacuation under
differing conditions.
Some judgment will be necessary
when considering the types of
protective actions to be implemented
and at what levels in an emergency
situation. Although the PAG is
expressed as a range of 1-5 rem, it is
emphasized that, under normal
conditions, evacuation of members of
the general population should be
initiated for most incidents at a
projected dose of 1 rem. (It should be
recognized that doses to some
individuals may exceed 1 rem, even if
protective actions are initiated within
this guidance.) It is also possible that
conditions may exist at specific
facilities which warrant consideration
of values other than those recom-
mended for general use here.3
Sheltering may be preferable to
evacuation as a protective action in
some situations. Because of the higher
risk associated with evacuation of some
special groups in the population (e.g.
those who are not readily mobile),
sheltering may be the preferred
alternative for such groups as a
EPA, in accordance with its responsibilities
under the regulations governing radiological
emergency planning (47FR10758; March 11,
1982) and under the Federal Radiological
Emergency Response Plan, will consult with
Federal agencies and the States, as requested,
in such cases.
2-5
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Table 2-1
PAGs for the Early Phase of a Nuclear Incident
Protective
Action
PAG
(projected dose)
Comments
Evacuation
(or sheltering*)
1-5 remb
Evacuation (or, for some
situations, sheltering*)
should normally be
initiated at 1 rem.
Further guidance is
provided in Section 2.3.1
Administration of
stable iodine
25 remc
Requires approval of
State medical officials.
"Sheltering may be the preferred protective action when it will provide protection equal to or
greater than evacuation, based on consideration of factors such as source term characteristics, and
temporal or other site-specific conditions (see Section 2.3.1).
sum of the effective dose equivalent resulting from exposure to external sources and the
committed effective dose equivalent incurred from all significant inhalation pathways during the
early phase. Committed dose equivalents to the thyroid and to the skin may be 5 and 50 times
larger, respectively.
Committed dose equivalent to the thyroid from radioiodine.
protective action at projected doses up
to 5 rem. In addition, under unusually
hazardous environmental conditions
use of sheltering at projected doses up
to 5 rem to the general population (and
up to 10 rem to special groups) may
become justified. Sheltering may also
provide protection equal to or greater
than evacuation due to the nature of
the source term and/or in the presence
of temporal or other site-specific
conditions. Illustrative examples of
situations or groups for which
evacuation may not be appropriate at 1
rem include: a) the presence of severe
weather, b) competing disasters, c)
institutionalized persons who are not
readily mobile, and d) local physical
factors which impede evacuation.
Examples of situations or groups for
which evacuation at 1 rem normally
would be appropriate include: a) an
2-6
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incident which occurs at night, b) an
incident which occurs when children
are in school, and c) institutionalized
persons who are readily mobile.
Evacuation seldom will be justified at
less than 1 rem. The examples
described above regarding selection of
the most appropriate protective action
are intended to be illustrative and not
exhaustive. In general, sheltering
should be preferred to evacuation
whenever it provides equal or greater
protection.
No specific minimum level is
established for initiation of sheltering.
Sheltering in place is a low-cost,
low-risk protective action that can
provide protection with an efficiency
ranging from zero to almost 100
percent, depending on the circum-
stances. It can also be particularly
useful to assure that a population is
positioned so that, if the need arises,
communication with the population can
be carried out expeditiously. For the
above reasons, planners and decision
makers should consider implementing
sheltering at projected doses below 1
rem; however, implementing protective
actions for projected doses at very low
levels would not be reasonable (e.g.
below 0.1 rem). (This guidance should
not be construed as establishing an
additional lower level PAG for
sheltering.) Sheltering should always
be implemented in cases when
evacuation is not carried out at
projected doses of 1 rem or more.
Analyses for some hypothesized
accidents, such as short-term releases
of transuranic materials, show that
sheltering in residences and other
buildings can be highly effective at
reducing dose, may provide adequate
protection, and may be more effective
than evacuation when evacuation
cannot be completed before plume
arrival (DO-90). However, reliance on
large dose reduction factors for
sheltering should be accompanied by
cautious examination of possible failure
mechanisms, and, except in very
unusual circumstances, should never be
relied upon at projected doses greater
than 10 rem. Such analyses should be
based on realistic or "best estimate"
dose models and include unavoidable
dose during evacuation. Sheltering and
evacuation are discussed in more detail
in Section 5.5.
2.3.2 Thyroid and Skin Protection
Since the thyroid is at
disproportionately high risk for
induction of nonfatal cancer and
nodules, compared to other internal
organs, additional guidance is provided
to limit the risk of these effects (see
footnote to Table 2-1). In addition,
effective dose, the quantity used to
express the PAG, encompasses only the
risk of fatal cancer from irradiation of
organs within the body, and does not
include dose to skin. Guidance is also
provided, therefore, to protect against
the risk of skin cancer (see Table 2-1,
footnote b).
The use of stable iodine to protect
against uptake of inhaled radioiodine
by the thyroid is recognized as an
effective alternative to evacuation for
situations involving radioiodine
releases when evacuation cannot be
2-7
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implemented or exposure occurs during
evacuation. Stable iodine is most
effective when administered
immediately prior to exposure to
radioiodine. However, significant
blockage of the thyroid dose can be
provided by administration within one
or two hours after uptake of radio-
iodine. If the administration of stable
iodine is included in an emergency
response plan, its use may be
considered for exposure situations in
which the committed dose equivalent to
the thyroid can be 25 rem or greater
(see 47 FR 28158; June 29, 1982).
Washing and changing of clothing
is recommended primarily to provide
protection from beta radiation from
radioiodines and particulate materials
deposited on the skin or clothing.
Calculations indicate that dose to skin
should seldom, if ever, be a controlling
pathway. However, it is good radiation
protection practice to recommend these
actions, even for alpha-emitting
radioactive materials, as soon as
practical for persons significantly
exposed to a contaminating plume (i.e.,
when the projected dose from inhala-
tion would have justified evacuation of
the public under normal conditions).
2,4 Dose Projection
The PAGs are expressed in terms
of projected dose. However, in the
early phase of an incident (either at a
nuclear facility or other accident site),
parameters other than projected dose
may frequently provide a more
appropriate basis for decisions to
implement protective actions. When a
facility is operating outside its design
basis, or an incident is imminent but
has not yet occurred, data adequate to
directly estimate the projected dose
may not be available. For such cases,
provision should be made during the
planning stage for decisions to be made
based on specific conditions at the
source of a possible release that are
relatable to ranges of anticipated
offsite consequences. Emergency
response plans for facilities should
make use of Emergency Action Leyels
(EALs)4, based on in-plant conditions,
to trigger notification of and
recommendations to offsite officials to
implement prompt evacuation or
sheltering in specified areas in the
absence of information on actual
releases or environmental
measurements. Later, when these data
become available, dose projections
based on measurements may be used,
in addition to plant conditions, as the
basis for implementing further
protective actions. (Exceptions may
occur at sites with large exclusion
areas where some field and source data
may be available in sufficient time for
protective action decisions to be based
on environmental, measurements.) In
the case of transportation accidents or
other incidents that are not related to
a facility, it will often not be
practicable to establish EALs.
The calculation of projected doses
should be based on realistic dose
Emergency Action Levels related to plant
conditions at commercial nuclear power plants
are discussed in Appendix 1 to NUREG-0654
(NB-80).
2-8
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models, to the extent practicable.
Doses incurred prior to initiation of a
protective action should not normally
be included. Similarly, doses that
might be received following the early
phase should not be included for
decisions on whether or not to evacuate
or shelter. Such doses, which may
occur from food and water, long-term
radiation exposure to deposited
radioactive materials, or long-term
inhalation of resuspended materials,
are chronic exposures for which neither
emergency evacuation nor sheltering
are appropriate protective actions.
Separate PAGs relate the appropriate
protective action derisions to those
exposure pathways (Chapter 4). As
noted earlier, the projection of doses in
the early phase need include only those
exposure pathways that contribute a
significant fraction (e.g., more than
about 10 percent) of the dose to an
individual.
In practical applications, dose
projection will usually begin at the
time of the anticipated (or actual)
initiation of a release. For those
situations where significant dose has
already occurred prior to implementing
protective action, the projected dose for
comparison to a PAG should not
include this prior dose.
2.5 Guidance for Controlling Doses to
Workers Under Emergency Conditions
The PAGs for protection of the
general population and dose limits for
workers performing emergency services
are derived under different
assumptions. PAGs consider the risks
to individuals, themselves, from
exposure to radiation, and the risks
and costs associated with a specific
protective action. On the other hand,
workers may receive exposure under a
variety of circumstances in order to
assure protection of others and of
valuable property. These exposures
will be justified if the maximum risks
permitted to workers are acceptably
low, and the risks or costs to others
that are avoided by their actions
outweigh the risks to which workers
are subjected.
Workers who may incur increased
levels of exposure under emergency
conditions may include those employed
in law enforcement, fire fighting,
radiation protection, civil defense,
traffic control, health, services,
environmental monitoring, transpor-
tation services, and animal care. In
addition, selected workers at
institutional, i utility, and industrial
facilities, and at farms and other
agribusiness may be required to protect
others, or to protect valuable property
during an emergency. The above are
examples - ;not designations - of
workers that may be exposed to
radiation undjer emergency conditions.
Guidance on dose limits for
workers performing emergency services
is summarized in Table 2-2. These
limits apply tp doses incurred over the
duration of an emergency. That is, in
contrast to the PAGs, where only the
future dose that can be avoided by a
specific protective action is considered,
all doses received during an emergency
are included in the limit. Further, the
dose to workers performing emergency
2-9
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Table 2-2 Guidance on Dose Limits for Workers Performing Emergency Services
Dose limit0
(rem)
Activity
Condition
10
25
>25
all
protecting valuable
property
life saving or
protection of large
; populations
lifesaving or
protection of large
populations
lower dose not practicable
lower dose not practicable
only on a voluntary basis
to persons fully aware of
the risks involved (See
Tables 2-3 and 2-4)
"Sum of external effective flose equivalent and committed effective dose equivalent to nonpregnant
adults from exposure and intake during an emergency situation. Workers performing services during
emergencies should limit dose to the lens of the eye to three times the listed value and doses to any
other organ (including skin and body extremities) to ten times the listed value. These limits apply to
all doses from an incident, except those received in unrestricted areas as members of the public during
the intermediate phase of the incident (see Chapters 8 and 4).
services may be treated as a once-in-a-
lifetime exposure, and not added to
occupational exposure accumulated
under nonemergency conditions for the
purpose of ascertaining eonformance to
normal occupational limits, if this is
necessary. However, any radiation
exposure of workers that is associated
with an incident, but accrued during
nonemergeney operations, should be
limited in accordance with relevant
occupational limits for normal
situations. Federal Radiation
Protection Guidance for occupational
exposure recommends an upper bound
of five rem per year for adults and one
tenth this value for minors and the
unborn (EP-87). We recommend use of
this same value here for the case of
exposures during an emergency. To
assure adequate protection of minors
and the unborn during emergencies,
the performance of emergency services
should be limited to nonpregnant
adults. As in the case of normal
occupational exposure, doses received
under emergency conditions should also
be maintained as low as reasonably
achievable (e.g., use of stable iodine,
where appropriate, as a prophylaxis to
2-10
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reduce thyroid dose from inhalation of
radioiodines and use of rotation of
workers).
Doses to all workers during
emergencies should, to the extent
practicable, be limited to 5 rem. There
are some emergency situations,
however, for which higher exposure
limits may be justified. Justification of
any such exposure must include the
presence of conditions that prevent the
rotation of workers or other
commonly-used dose reduction
methods. Except as noted below, the
dose resulting from such emergency
exposure should be limited to 10 rem
for protecting valuable property, and to
25 rem for life saving activities and the
protection of large populations. In the
context of this guidance, exposure of
workers that is incurred for the
protection of large populations may be
considered justified for situations in
which the collective dose avoided by
the emergency operation is signif-
icantly larger than that incurred by the
workers involved.
Situations may also rarely occur in
which a dose in excess of 25 rem for
emergency exposure would be
unavoidable in order to carry out a
lifesaving operation or to avoid
extensive exposure of large populations.
It is not possible to prejudge the risk
that one should be allowed to take to
save the lives of others. However,
persons undertaking any emergency
operation in which the dose will exceed
25 rem to the whole body should do so
only on a voluntary basis and with full
awareness of the risks involved,
including the numerical levels of dose
at which acute effects of radiation will
be incurred and numerical estimates of
the risk of delayed effects.
Tables 2-3 and 2-4 provide some
general information that may be useful
in advising emergency workers of risks
of acute and delayed health effects
associated with large doses of radia-
tion. Table 2-3 presents estimated
risks of early fatalities and moderately
severe prodromal (forewarning) effects
that are likely to occur shortly after
exposure to a wide range of whole body
radiation doses. Estimated average
cancer mortality risks for emergency
workers corresponding to a whole-body
dose equivalent of 25 rem are given in
Table 2-4, as a function of age at the
time of exposure. To estimate average
cancer mortality for moderately higher
doses the results in Table 2-4 may be
increased linearly. These values were
calculated using a life table analysis
that assumes the period of risk
continues for the duration of the
worker's lifetime. Somewhat smaller
risks of serious genetic effects (if
gonadal tissue is exposed) and of
nonfatal cancer would also be incurred.
An expanded discussion of health
effects from radiation dose is provided
in Appendix B.
Some workers performing
emergency services will have little or
no health physics training, so dose
minimization through use of protective
equipment cannot always be assumed.
However, the use of respiratory
protective equipment can reduce dose
from inhalationf and clothing can
reduce beta dose. Stable iodine is also
recommended for blocking thyroid
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Table 2-3 Health Effects Associated with Whole-Body Absorbed Doses Received
Within a Few Hours* (see Appendix B)
Whole Body
Absorbed dose
(rad)
140
200
300
400
460
Early
Fatalitiesb
(percent)
5
15
50
85
95
Whole Body
Absorbed dose
(rad)
50
100
150
200
250
Prodromal Effects0
(percent affected)
2
15
50
85
98
"Risks will be lower for protracted exposure periods,
bSupportive medical treatment may increase the dose at which
tihese frequencies occur by approximately 50 percent.
forewarning symptoms of more serious health effects associated
with large doses of radiation.
Table 2-4 Approximate Cancer Risk to Average Individuals from 25 Rem Effective
Dose Equivalent Delivered Promptly (see Appendix C)
Age at
exposure
(years)
20 to 30
30 to 40
40 to 50
50 to 60
Appropriate risk
of premature death
(deaths per 1,000
persons exposed)
9.1
7.2
5.3
3.5
Average years of
life lost if premature
death occurs
(years)
24
19
15
11
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uptake of radioiodine in personnel
involved in emergency actions where
atmospheric releases include
radioiodine. The decision to issue
stable iodine should include
consideration of established State
medical procedures, and planning is
required to ensure its availability and
proper use.
References
DO-90 U.S. Department of Energy.
Effectiveness of Sheltering in Buildings and
Vehicles for Plutonium, DOE/EH-0159, U.S.
Department of Energy, Washington (1990).
EP-87 U.S. Environmental Protection Agency.
Radiation Protection Guidance to Federal
Agencies for Occupational Exposure. Federal
Register. 52, 2822; January 27, 1987.
NR-80 U.S. Nuclear Regulatory Commission.
Criteria for Preparation and Evaluation of
Radiological Emergency Response Plans and
Preparedness in Support of Nuclear Power
Plants. NUREG-0654, U.S. Nuclear
Regulatory Commission, Washington, (1980).
2-13
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CHAPTER 3
Protective Action Guides for the Intermediate Phase
(Food and Water)
a) Accidental Radioactive Contamination of Human Food and Animal Feeds;
Recommendations for State and Local Agencies*
b) Drinking Water**
* These recommendations were published by FDA in 1982.
"""Protective action recommendations for drinking water are under development by
EPA.
3-1
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Federal Register / Vol. 47. No. 205 / Friday. October 22,! 1982 / Notices
DEPARTMENT OF HEALTH AND
HUMAN SERVICES
Food and Drug Administration
[Docket No. 76N-0050]
Accidental Radioactive Contamination
of Human Food and Animal Feeds;
{Recommendations for State and Local
Agencies
AO.ENCY: Food and Drug Administration.
ACTION: Notice.
SUMMARY: The Food and Drug
Administration (FDA) is publishing this
notice to provide to State and local
agencies responsible for emergency
response planning for radiological
incidents recommendations for taking
protective actions in the event that an
incident causes the contamination of
human food or animal feeds. These
recommendations can be used to
determine whether levels of radiation
encountered in food after a radiological
incident warrant protective action and
to suggest appropriate actions that may
be taken if action is warranted. FDA has
a responsibility to issue guidance on
-------
47074
Federal Register / Vol. 47. No. 205 / Friday, October 22, 1982 / Notices
appropriate planning actions necessary
for evaluating and preventing
contamination of human food and
animal feeds and on the control and use
of these products should they become
contaminated.
FOR FURTHER INFORMATION CONTACT:
Gail D. Schmidt, Bureau ofRadiologic.il
Health (HFX-1). Food and Drug
Administration, 5600 Fishers Lane,
Ruckville, MD 20857, 301-443-2850.
SUPPLEMENTARY INFORMATION:
Background
This guidance on accidental
radioactive contamination of food from
fixed nuclear facilities, transportation
accidents, and fallout is part of a
Federal interagency effort coordinated
by the Federal Emergency Management
Agency (FEMA). FEMA issued a final
regulation in the Federal Register of
March 11,1982 (47 FR10758), which
reflected governmental reorganizations
and reassigned agency responsibilities
for radiological incident emergency
response planning. A responsibility
assigned to the Department of Health
and Human Services (HHS) (and in turn
delegated to FDA) is the responsibility
to develop and specify to State and local
governments protective actions and
associated guidance for human food and
animal feed.
In the Federal Register of December
15,1978 (43 FR 58790), FDA published
proposed recommendations for State
and local agencies regarding accidental
radioactive contamination of human
food and animal feeds. Interested
persons were given until February 13,
1979 to comment on the proposal.
Twenty-one comments were received
from State agencies, Federal agencies,
nuclear utilities, and others. Two of the
comments from environmentally
concerned organizations were received
after the March 28,1979 accident at
Three Mile Island, which increased
public awareness of protective action
guidance. Although these comments
were received after the close of the
comment period, they were considered
by the agency in developing these final
recommendations.
The Office of Radiation Programs,
Environmental Protection Agency (EPA),
submitted a detailed and exhaustive
critique of the proposed
recommendations. EPA addressed the
dosimetry data, the agricultural models
used in calculating the derived response
levels, and the philosophical basis for
establishing the numerical value of the
protective action guides. FDA advises
that, to be responsive to the EPA
comments, FDA staff met with staff of
the Office of Radiation Programs, EPA,
during the development of these final
recommendations. Although EPA's
formal comments are responded to in
this notice, EPA staff reviewed a draft of
the final recommendations, and FUA
has considered their additional informal
comments. These contacts wers
conoidered appropriate because EPA
has indicated that it intends to use the
recommendations as the basis for
revising its guidance to Federal agencies
on protective action guides for
radioactivity in food.
Protective Action Guidance
Although not raised in the comments
received, FDA has reconsidered its
proposal to codify these
recommendations in 21 CFR Part 1090.
Because these recommendations are
voluntary guidance to State and local
agencies (not regulations), FDA has
decided not to codify the
recommendations; rather, it is issuing
them in this notice. Elsewhere in this
issue of the Federal Register, FDA is
withdrawing the December 15,1978
proposal.
The recommendations contain basic
criteria, defined as protective action
guides (PAG's), for establishing the level
of radioactive contamination of human
food or animal feeds at which action
should be taken to protect the public
health and assure the safety of food. The
recommendations also contain specific
guidance on what emergency protective
actions should be taken to prevent
further contamination of food or feeds or
to restrict the use of food, as well as
more general guidance on the
development and implementation of
emergency tstion. The PAG's have been
developed on the basis of
considerations of acceptable risk to
identify that level of contamination at
which action is necessary to protect the
public health.
In preparing these recommendations,
FDA has reviewed and utilized the
Federal guidance on protective actions
contained in Federal Radiation Council
(FBC) Reports No. 5, July 1964 (Ref. 1)
and No. 7, May 1965 (Ref. 2J. The
Federal guidance provides that each
Federal agency, by virtue of its
immediate knowledge or its operating
problems, would use the applicable FRC
guides as a basis for developing detailed
standards to meet the particular needs
of the agency. FDA's recommendations
incorporate the FRC concepts and the
FRC guidance that protective actions, in
the event of a contaminating accident,
should be based on estimates of the
projected radiation dose that would be
received in the absence of taking
protective actions. Similarly, protective
actions should be implemented for a
sufficient time to avoid most of the
projected radiation dose. Thus, the
PAG's define the numerical value of
projected radiation doses for which
protective actions are recommended.
FDA has reviewed the recent report of
the National Academy of Sciences/
National Research Council (Ref. 3) on
radiation risks and biological effects
data trwt became available after
publiciilion of the FRC guidance and has
reviewed the impact of taking action in
the pjisture/cow/milk/person pathway
in light of the current concerns in
radiation protection. Based on these
considerations and the comments
received on the proposed
recommendations, FDA has concluded
that protective actions of low impact
should be undertaken at projected
radiation doses lower than those
recommended by FRC (Refs. 1 and 2).
Accordingly, FDA is recommending low-
impact protective actions (termed the
Preventive PAG) at projected radiation
doses of 0.5 rem whole body and 1.5 rem
thyroid. FDA intends that such
protective actions be implemented to
prevent the appearance of radioactivity
in food at levels that would require its
condemnation. Preventive PAG's
include the transfer of dairy cows from
fresh forage (pasture) to uncontaminated
stored feed and the diversion of whole
milk potentially contaminated with
short-lived radionuclides to products
with a long shelf life to allow
radioactive decay of the radioactive
material.
In those situations where the-only
protective actions that are feasible
present high dietary and social costs or
impacts (termed the Emergency PAG)
action is recommended at projected
radiation doses of 5 rem whole body
and 15 rem thyroid. At the Emergency
PAG level responsible officials should
isolate food to prevent its introduction
into commerce and determine whether
condemnation or other disposition is
appropriate. Action at the Emergency
PAG level is most likely for the
population that is near to the source of
radioactive contamination and that
consumes home-grown produce and
milk.
The PAG's represent FDA's judgment
as to that level of food contamination
resulting from radiation incidents at
which action should be taken to protect
the public health. This is based on the
agency's recognition that safety involves
the degree to which risks are judged
acceptable. The risk from natural
disasters (approximately a one in a
million annual individual risk of death)
and the risk from variations in natural
background radiation have provided
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Fedeta! Register / Vol. 47.. No. 205 / Friday. October 22, 1982L/
perspective in selecting the PAG values.
This issue is further discussed In the
responses to specific comments later in
this notice, especially in paragraph 9. A
more detailed treatment of the rationale,
risk factors, dosimetric and agricultural
models, and methods of calculation is
contained in the "Background for
Protective Action Recommendations;
Accidental Radioactive Contamination
of Food and Animal Feeds" (Ref, 22),
Organ PAG Values
Current scientific evidence, as
reflected by BEIR-I {Ref. 18),
UNSCEAR-1977 (Ref. 8), and BEIR-I1I
(Ref. 3), indicates that the relative
importance of risk due to specific organ
exposure is quite different from the
earlier assumptions. The International
Commission on Radiological Protection
(ICRP) clearly recognized this in its 1977
recommendations (ICRP-28 (Ref, 6)J,
which changed the methodology for
treating external and internal radiation
doses and the relative importance of
specific organ doses, ICRP-26 assigned
weighting factors to specific organs
based on considerations of the
Incidence and severity (mortality) of
radiation cancer induction. For the
radionuclides of concern for food PAG's,
ICRP-28 assigned weighting factors of
0,03 for the thyroid and 0,12 for red bone
marrow. Thus, the organ doses equal in
risk to 1 rent whole body radiation dose
are 33 rem to the thyroid and 8 rem to
Red bone marrow, (The additional
ICRP-28, nonstochastic limit, however,
restricts the thyroid dose to 50 rem or 10
times the whole body occupational limit
of 5 rem.)
In the Federal Register of January 23,
1981 (46 FR 7836}, EPA proposed to
revise the Federal Radiation Protection-
Guidance for Occupational Exposures
using the ICRP approach for internal
organ radiation doses, modified to
reflect specific EPA concerns. The EPA
proposal has been subject to
considerable controversy. Also, the
National Council on Radiation
Protection and Measurements (NCRPJ
curently is evaluating the need to revise
its recommendations. FDA does not,
however, expect the protection model
for internal organ radiation doses to be
resolved rapidly in the United States
and has based the relative PAG dose
assignments in these recommendations
on current U.S. standards and the 1971
recommendations in NCRP-39 (Ref. 19),
Thus, the red bone marrow is assigned
the same PAG dose as the whole body
(0.1 rem Preventive PAG), and the
thyroid PAG is greater by a factor of
three (1.5 rem Preventive PAG). This
results in PAG assignments for the
thyroid and red bone marrow that are
lower by factors of 3,3 and 8,
respectively, than values based on
ICRP-28 (Ref. i). FDA advises that it
will make appropriate changes in
recommendations for internal organ
doses when a consensus in the United
Slates emerges.
Analysis of Comments
The following Is a summary of the
comments received on the December IS,
1978 proposal and the agency's response
to them:
1. Several comments requested
clarification of the applicability and
compatibility of PDA's
recommendations with other Federal
actions, specifically the PAG guidance
of EPA (Ref. 7), the FRC Reports No. 5
(Ref. 1) and No. 7 (Ref. 2), and the
Nuclear Regulatory Commission (NRC)
definition of "Extraordinary Nuclear
Occurrence" in 10 CFR Part 140. A
comment recommended that the term,
"Protective Action Guide (PAG)", not be
used because that term traditionally has
been associated with the FRC, and the
general public would confuse FDA's
recommendations with Federal
guidance.
The FRC Report No. S specifically
recommended that the term, "protective
action guide," be adopted for Federal
use. The report defines the term as the
"projected absorbed dose to the
individuals in the general population
which warrants protective action
following a contaminating event," a
concept that is addressed by FDA's
recommendations. To use the concept
with a different description would, in
FDA's opinion, be unnecessarily
confusing to State and local agencies as
well as Federal agencies.
These recommendations are being
issued to fulfill the HHS responsibilities
under FEMA's March 11,1982
regulation. FDA fully considered FRC
Reports No. 5 and No. 7 and the basic
concepts and philosophy of the FRC
guidance form the basis for these
recommendations. The specific PAG
values are derived response levels
included in these recommendations are
based on current agricultural pathway
and radiation dose models and current
estimates of risk. The FRC guidance
provided that protective actions may be
justified at lower (or higher) projected
radiation doses depending on the total
impact of the protective action. Thus,
FDA's recommendation that protective
actions be implemented at projected
radiation doses lower than those
recommended by FRC doses is
consistent with the FRC guidance. The
FRC guidance is applicable to Federal
• agencies in their radiation protection
activities. FDA's recommendations are
for use by State and local agencies in
response planning and implementation
of protective actions in the event of a
contaminating incident. Further, FDA's
recommendations would also be used by
FDA in implementing its authority for
food in interstate commerce under the
Federal Food, Drug, and Cosmetic Act
FDA's recommendations are being
forwarded to EPA as the basis for
revising Federal guidance on food'
accidentally contaminated by
radionuclides, EPA has advised FDA
that }t intends to forward the FDA
recommendations to the President under
its authority to "advise the President
with respect to radiation matters
directly or indirectly affecting health,
including guidance for all Federal
agencies In the formulation of radiation
standards * * *", (This authority was
transferred to EPA in 1970 when FRC
was abolished.}
The recommendations established in
this document apply only to human food
and animal feeds accidentally
contaminated by radionuclides. They
should not be applied to any other
source of radiation exposure. EPA
already has issued protective action
guidance for the short-term accidental
exposure to airborne releases of
radioactive materials and intends also
to forward the EPA guides to the
President as Federal guidance, EPA also
is considering the development of
guidance for acidentaliy contaminated
water and for long-term exposures due
to contaminated land, property, and
materials. Guidance for each of these
exposure pathways is mutually
exclusive. Different guidance for each
exposure pathway is appropriate
because different criteria of risk, cost,
and benefit are involved. Also, each
exposure pathway may involve different
sets of protective or restorative actions
and would relate to different periods of
time when such actions would be taken,
2, Several comments expressed
concern about radiation exposure from
multiple radionuclides and from multiple
pathways, e.g., via inhalation, ingestion,
and external radiation from the cloud
(plume exposure) and questioned why
particular pathways or radionuclides
and the does received before
assessment were not addressed in the
recommendations. Several comments
recommended that the PAG's include
specific guidance for tap water (and
potable water). Other comments noted
that particular biological forms of
specific radionuclides {i.e.,
cyanocobalamin Co 60), would lead to
significantly different derived response
levels.
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47076
Federal Register / Vol. 47. No. 205 /Friday. October 22, 1982 / Notices
FDA advises that {he PAG's and the
j.roteclive action concepts of FRC apply
(a actions taken to avoid or prevent
projected radialion doae (or future
dose). Thus, by definition, the PAG's for
food do not consider the radiation dosos
alraady incurred from the plume
pathway or from other sources. The
population potentially exposed by
ingestion of contaminated food can be
divided into that population near the
source of contamination and a generally
much larger population at distances
where the doses from the cloud are not
significant. The NRG regulations provide
(hat State and local planning regarding
plume exposure should extend for 10
miles and the ingestion pathway should
extend for 50 miles (see 45 FR 55402;
August 19,1980). The total population
exposed by ingestion, however, is a
function of the animal feed and human
food production of any given area and is
not limited by distance from the source
of cdnlamination. Exposure from
multiple pathways would not be a
concern for the more distant population
group. Further, individuals in this larger
population would most likely receive
doses smaller than that projected for
continuous intake because the
contaminated food present in the retail
distribution system would be replaced
by uncontarninated food.
FRC Report No. 5 states that, for
repetitive occurrences, the total
projected radiation dose and the total
impact of protective actions should be
considered. Similar considerations on a
case-by-case basis would then appear to
be appropriate in the case of multiple
exposures from the plume and the
ingestion pathway. Accordingly, the
final recommendations are modified to
note that, specifically in the case of the
population near the site that consumes
locally grown produce, limitations of the
total" dose should be considered (see
paragraph (a){2)). The agency concludes,
however, that a single unified PAG
covering multiple pathways, e.g.,
external radiation, inhalation, and
ingeslion is not practical because
different actions and impacts are
involved. Further, FDA's responsibility
in radiological incident emergency
response planning extends only to
human food and animal feeds.
The agency's primary charge is to set
recommended PAG dose commitment
limits for the food pathway. Thus,
deriving response levels for only the
radfonuclides most likely to enter the
food chain and deliver the highest dose
to the population permits FDA to
establish recommendations that are
practical for use in an emergency. In
discussing with EPA the list of definitive
modclb. FDA and EPA staffs agreed that
further pathway studios would be
useful. Elsowhejre in this notice. FDA
references models for other
radionudifles. providing a resource? for
those requiring more details.
The chemical form of rariionuelides in
the environment may be important wh
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Fetfaral Register / VqL 47. No. 205 / Friday. October 22. .1982 / Notices
47877
shipment of contaminated foods from
States without sufficient resources and
what would be the applicable PAG.
FEMA. as the lead agency for the
Federal effort, is providing to States
guidance and assistance on emergency •
response planning including evaluation
of projected doses. Also. NRG requfaea
nuclear power plant licensees to have
the capability to assess the off-site
consequences of radioactivity releases
and to provide notification to Slate and
local agencies (45 FR 55402; August 19.
1880). FDA has authority under the
Federal Food. Drug, and Cosmetic Act to
remove radfoaetively contaminated food
from the channels of interstate
commerce. In this circumstance, FDA
would use these PAG recommendations
as lh« basis for implementing
regulatory action.
Risk Estimates
7. Many comments questioned the risk
estimates on which FDA based the
proposed PAG'a. The comments
especially suggested that risk estimates
from WASH-14QQ (let. 4J were of
questionable validity. Other comments
argued that the proposed
recommendaSons used an analysis of
only ledial effects; that they wed an
absolute risk mod'afc and that genetic
effects were not adequately considered.
The risk estimates themselves were
alleged to be erroneous because recent
studies show that doubling doses are
lower than are those suggested by
WASH=1400. The tinea capitis study by
Eon and Modan. which indicates an
increased probability of thyroid cancer
at an estimated radiation dose of 9 rem
to the thyroid (Ref, S), was cited as
evidence that the PAG limits for the
thyroid were loo high. The comments
rea.uosfad further identification and
support for using the critical population
selected,
Most af these issues were addressrd
in the preamble to the FDA proposal.
The final recommendations issued to
this notice employ the most recent risk
estimates (somatic and genetic} of the
National Academy of Sciencen
Cannrttitee on Biological Effects of
Ionizing Sadiatfan (Ref. 3).
The thyroid PAG limits are based on
the relative radiation protection guide
for thyroid compared to whole-body
contained in NRC's current regulations
(10 CFE Part 2QJ, The derived response
levels for thyroid are based on risk
. factors for external x-ray irradiation,
Therefore, the criticism of the PAG
limit* for the thyroid is not applicable,
no •*crerfit" having been taken, for as
apparent lower radiation risk due to
lodioe-131 irradiation of tba thyroid
gland. Farther, as discussed above
under "G1GAN PAG VALUES", the use
of BEIR-1II risk estimates or the ICRP-26
recommendations would result in an
Increase of the thyroid PAG relative to
the whole body PAG. For &ese reasons,
FDA believes the PAG limite for
projected dose commitment to the
thyroid are conservative when
considered in light of current knowledge
of radiation to produce equal health
risks from whole body and specific
organ doses.
Although it may be desirable to.
consider total health effects, not just
lethal effects, there is a lack of data far
total health effects to ose in such
comparisons. In the case of the
variability of natural background, aa an
estimate of acceptable risk,
consideration of lethal effects or total
health effects is not involved because
the comparison is the total dose over a
lifetime.
Rational
S, Several comments questioned the
rational FDA used in setting the specific
PAG values included in the December
1978 proposal. A comment from EPA
stated that the guidance levels should be
justified on the grounds that it is not
practical or reasonable to take
protective actions at lower risk levels.
Further, EPA argued that the protective
action-concept for emergency planning
and response should incorporate the
principle of keeping radiation exposures
as low as reasonably achievable
[ALARA). SPA noted that the principle
of acceptable risk involves a perception
of risk that may vary front person to
person and that the implication that an
acceptable genetic risk has been
established should be avoided.
FDA accepts and endorses the
ALARA concept, but the extent to which
a concept, which 5s used in occupational
settings, should be applied to emergency
protective actions is not clear. To use
the ALARA concept as the basis for
specific PAG values and also require
ALARA during the implementation of
emergency protective actiona appears to
be redundant and may not be practical
under emergency conditions.
FDA advises that these guides do not
constitute acceptable occupational
radiation dose limits nor do they
constitute acceptable limits for other
applications (e.g., acceptable genetic
risk). The guides are not intended to be
used to limit the radiation dose that
people may receive but instead are to be
compared to the calculated projected
dose, i.e., the future dose that the people
would receive if no protective action
were taken in a radiation emergency. In
this respect, the PAG'a represent trigger
levels calling for the initiation of
recommended protective actions. Once
the protective action is initiated, it
should be executed act as to prevent as
much of the calculated projected dose
from being received aa is reasonably
achievable. This does not mean,
however, that al! doses above guidance
levels can be prevented;
Further, the guides are not intended to
prohibit taking actions at projected
exposures lower than the PAG values.
They have been derived for general
eases and ace just what their mams
Implies, guides. As provided kz ISC
leports No. S and No. 7 sxuLm
discussed in paragraph 1 of thi» notice.
in the absence of significant eootteainta,
responsible authority, nay find it
appropriate to implement low-impact
protective acif out at projected radiation
doses less than those specified in the
guides. SinularIy,.lrigJi impact aetionr
may be justified at high** projected
doses. These judgments- musi be made
according to the facts of «aeh sifnatwa,
Paragraphs (a) {2} and (3} have beea
added to the final nscomsriendatMaa to
Incorporate this concept.
9. Several comments questioned the-
adequacy of the level ofiiak fadgeti
acceptable in deriving the proposed
PAG values. A comimen* stated that the
estimated one in a millioa aanuai
individual risk of death tram aafcral
disasters is extremely, conservative. EPA
suggested that comparative risk is
appropriate for perspective but aat foe
establishing the lirmts-.EPA fiirtfaer
suggested that the population-weighted
average of the variability in natural
background dose or the variation in
dose due to the natural radioactivity ia
food should be the basis for judging
acceptable risk.
FDA concludes that the differences
between EPA'« suggested approach and
that employed by EDA largely involve
the semantics of the, rationale
descriptions. As discussed in. the
preamble to the proposal. FDA"6el!ave«
that safety (or a safe level of riaic) needs
to he defined as'tfaa degree to which the
risks are judged acceptable, because it
is' not possible to achieve yam risk from
human endeavors. Further, ICSP (Ref. 8}
recommends that, for a given
application involving radiation, the net
benefit to society should be positive,
considering the total costs and impacts
and the total benefit (this is termed.
"justification"}. FDA believes that to
establish a PAG. the primary concern is
to provide adequate protection {or safe
level of risk) for members of the public.
To decide on safety or levels of
acceptable risk to the public from a
contaminating event. FDA introduced
the estimates of acceptable risk from
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47078 Federal Register / Vol. 47. No. 205 / Friday. October 22. 1982 / Notices
natural disasters and background
riidiation. These values provided
background or perspective for FDA's
judgment that the proposed PAG's
represent that level of food or feed
radiation contamination at which
protective actions should be taken to
protect the public health; judgment
which, consistent with FRC Report No,
5, also involves consideration of the •
impacts of the action and the possibility
of future events. The recommendations
are based on the assumption that the
occurrences of environmental
contamination requiring protective
actions in. a particular area is an
unlikely event, that moat individuals
will never be so exposed, and that any
individual ia not likely to be exposed to
projected doses at the PAG level more
than once in his or her lifetime.
FDA continues to believe that the
average risks from natural disasters and
variation of background radiation
provide appropriate bases for judging
the acceptability of risk represented by
tho Preventive PAG. These
recommendations incorporate the •
philosophy that action should be taken
at the Preventive PAG level of
contamination to avoid a potential
public health problem. Should this
action not be wholly successful, the
Emergency PAG provides guidance for
taking action where contaminated food
is encountered. FDA expects that action
at the Emergency PAG level of
contamination would most likely
involve food produced for consumption;
by the population near the source of
contamination. As discussed in
paragraph 2, this Is also the population
which might receive radiation doses
from multiple pathways. Thus, the
Emergency PAG might be considered to
be an upper bound for limiting the total
radiation dose to individuals. FDA
emphasizes, however, that the
Emergency PAG is not a boundary
between safe levels and hazardous or
injury levels of radiation. Individuals
may receive an occupational dose of 5
tern each year over their working
lifetime with the expectation of minimal
increased risks to the individual.
Persons in high elevation areas such as
Colorado receive about 0.04 rem per
year (or 2,8 rem in a lifetime) above the
average background radiation dose for
the United States population as a whole.
The Emergency PAG is also consistent
with the upper range of PAG's proposed
by EPA for the cloud (plume) pathway
(Ref. 7,),
FDA agrees that a population-
weighted variable is as applicable to the
evaluation of comparative risks as is a
geographic variable. Arguments can be
made for using either variable. Because
persons rather than geographic areas
are the important parameter in the
evaluation of risk associated with these
guides, FDA has used population-
weighting in estimating the variability of
the annual external dose from natural
radiation. A recent EPA study (Ref. 20)
indicates that the average population
dose from external background
radiation dose is 53 millirem (mrcm) per
year, and the variability in lifetime dose
taken as two standard deviations is
about 2,000 mrem. The proposal, which
indicated that the variation in external
background was about 600 mrem,
utilized a geographic weighting of State
averages.
Radioactivity in food contributes
about 20 mrem per year to average
population doses and about 17 mrem per
yearef4h|sdose results from potassium-
40 (Ref. 8)?Steasurements of potassium-
40 (and stable potassium) indicate that
variability (two standard deviations) of
the potassium-40 dose is about 28
percent or a lifetime dose of iSO mrem. It
should be noted that body levels of
potassium are regulated by metabolic
processes and not dietary selection or
residence. The variation of the internal
dose is about one-fifth of the variation
from external background radiation.
FDA has retained the proposed
preventive PAG of 500 mrem whole
body even though the newer data
indicate a greater variation in external
background radiation.
FDA did not consider perceived risks
in deriving the proposed PAG values
because perceived risk presents
numerous problems in its
appropriateness and application. If the
factor of perception is added to the
equation, scientific analysis is
impossible.
10. Two comments questioned the
assumptions that the Emergency PAG
might apply to 15 million people and
that the Preventive PAG might apply to
the entire United States. One comment
noted that 15 million persons are more
than that population currently within 25
miles of any United States reactor sites:
thus, using this figure results in guides
more.restrictive than necessary. The
other comment noted that, by reducing
the population involved, and,
unacceptably high value could result.
The ratio of total United States
population to the maximum number of
people in the vicinity of an operating
reactor could be erroneously interpreted
so that progressively smaller
populations would be subject to
progressively larger individual risks.
This is not the intent of the
recommendations. Hence, the risk from
natural disasters, the variation in the
population-weighted natural background
radiation dose to the total population.
and the variation in dose due to
ingostion of food, have been used to
provide the basis for the Preventive
PAG, The basis for the Emergency PAG
involves considerations of (1) The ratio
between average and maximum
individual radiation doses (taken as I to
10), (2) the cost of low and high impact
protective actions, (3) the relative risks
from natural disasters, (4) health impact,
(5) the upper range of the PAG's
proposed by EPA (5 rem projected
radiation dose to the whole body and 25
rem projected dose to the thyroid), and
(6) radiation doses from multiple
pathways.
11, A comment, citing experience with
other contaminants, suggested that
further consideration should be given to
the problem of marketability of foods
containing low levels of radioactivity.
Marketability is not a concern for
PAG development. However, the
publication of the PAG's should enhance
marketability of foods because it will
enhance public confidence in food
safety. Also, FEMA has been
specifically directed to undertake a
public information program related to
radiation emergencies to allay public
fears and perceptions.
12. A comment noted the difficulty in
assessing the impacts of and the
benefits to be gained from protective
actions. Another comment suggested
that there were lower impact actions
which could be implemented to keep
food off the market until radiation levels
in the food approach normal
background.
The recommendation that planning
officials consider the impacts of
protective actions in implementing
action does not imply that a
mathematical analysis is required.
Rather, FDA intends that the local
situation, resources, and impacts that
are important in assuring effective
protective actions be considered in
selecting any actions to be implemented.
As discussed in paragraph 8, if the local
constraints permit a low impact action,
this can be appropriate at lower
projected doses. Because it is not
possible in general guidance to consider
fully all local constraints, the PAG's '
represent FDA's judgment as to when
protective actions are appropriate.
Agricultural and Dose Models
13. Several comments noted errors
either in approach or calculations
regarding the proposed agricultural and
dose models, while others specifically
noted that there are newer and better
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Federal Eepster / Vol. 47. No. 205 / Friday. October 22. 1982 / Notices 47078
models for use in computation of the
derived response levels.
FDA appreciates the careful review
and the suggestions as to better data
and models. The references suggested,
as well as other current reports, have
been carefully reviewed and appropriate
ones are being used as the basis for
computation of the derived response
levels for the final PAG's. The specific
models and data being used are as
follows:
Agricultural Model—UCRL^1938.1977
(Ref. 9).
Intake per unit deposition—Table B-l.
UCRL-51939 (Ref. 9).
Peak milk activity—Equation 8. UCRL-
51939 (Ref. 9),
Area grazed by cow—45 square meters/
day. UCRL-51B39 (Ref. 9).
Initial retention on forage—0.5 fraction.
UCRL-S1939 {Ref. 9).
Forage yield—0.25 kilogram/square meter
(dry weight). UCRL-SW39 (Ref. 9).
Milk consumption—0.7 liter/day infant, .
ICRP-23,1874 (Ref. 10);—0.55 liter/day adult.
USDA, 1985 (Ref. 11),
Dose conversion factors (rem per
microcurie ingested).
to^.,3,
Ceswm»i 34.. „,.,,„
Owium- 13? .,..„,..,
StrQ5tajm-6B
SJr»>r.tium-9G . ......
M*«
1*
0.118
0.071
0.194
2.49
j
M*
1.6
0.068
0.081
0.012
0,70
WsHmjmand Anger,
1971 ffW. 12).
AduK— ORNL/NUREQ/
TM-190. 197S (Ret.
13).
Infant — BitrapoUried
(rani aduM b««d cm
return* body wcigM
70 kilograms (tigi and
7.7 kg KM «"octtv«
roionuxi. 102 day*
and 19.S days, adult
•nd infant
NCRP NO. 52, 1977
(Blf 14).
Adult, CRP-30. 1979
(Ret. 15).
InffHut. P«pwort!i and
VeinM, 1973 (Rat.
16).
The use of the newer agricultural
model (Ref. 9) has resulted in a 20
percent increase in the iodine-131
. derived response levels identified in
paragraph (d)(lj and (d)(2) of the
recommendations. Generally, similar
magnitude changes are reflected in the
derived response levels for the other
radionuclides. Newer data on iodine-131
dose conversion factors (Ref. 17) would
have further increased the derived
response levels for that radionuclide by
about 40 percent, but these data have
not been used pending their acceptance
by United States recommending
authorities. In addition, the proposal .
contained a systematic error in that the
pasture derived response levels were ,
stated to be based on fresh weight but
were in fact based on dry weight. Fresh
weight values (% of dry weight values)
tire identified in the final
recommendations and are listed under
"Forage Concentration".
Other Comments
14. A comment addressed the
definition of the critical or sensitive
population for the tables in proposed
§ 1090.400(d) and observed that there is
a greater risk per rem to the younger age
groups than to adults. Another comment
requested further explanation of the
relative ability to protect children and
adults.
FDA agrees that, ideally., the critical
segment of the population should be
defined in terms of the greatest risk per
unit intake. However, this would
introduce greater complexity into the
recommendations than, is justified,
because the risk estimates are uncertain.
The final recommendations provide
derived response levels for infants'at the
Preventive PAG and infants and adults
for the Emergency PAG."
FDA has reexamined the available
data and concludes that taking action at
the Preventive PAG (based on1 the infant
as the critical or sensitive population)
will also provide protection of the fetus
from the mother's ingestion of milk. The
definition,of newborn infant in the
tables in paragraph (d) of the PAG's has
been revised to reflect this conclusion.
15. EPA commented that its
regulations governing drinking water (40
CFR Subchapter D) permit blending of
water to meet maximum contaminant
levels. EPA suggested that FDA's short-
term recommendations should be
compatible with the long-term EPA
regulations.
As stated in paragraphs 1 and 2 of this
notice, FDA's recommendations apply to
human food and animal feed, whereas
EPA is responsible for providing
guidance on contaminated water. Also,
as discussed in paragraph 3 of the
proposal, there is a long-standing FDA
policy that blending of food is unlawful
under the Federal Food, Drug, and
Cosmetic Act. -Further, these guides are
intended for protective actions under
emergency situations and are not for
continuous exposure applications. For
these reasons, FDA concludes that the
differences between its
recommendations and EPA's regulations
are appropriate.
16. Two comments were received on
the adequacy or availability of
resources for sampling and analysis of
State, local, and Federal agencies and
the adequacy of guidance on sampling
procedures.
These recommendations are not
designed to provide a compendium of
sampling techniques, methods, or
resources. The Department of Energy
through its Interagency Radiological
Assistance Plan (IRAPJ coordinates the
provision of Federal assistance and an
Offsite Instrumentation Task Force of
the Federal Radiological Preparedness
Coordinating Committee administered
by, FEMA is developing specific
guidance on instrumentation and
methods for sampling food (Ref. 21}',
Cost Analysis
17. Several comments argued that
FDA's cost/benefit analysis-used to
establish the PAG level* was
inadequate. Comments stated that it is
not appropriate to assign a unique fixed
dollar value to the adverse health
effects associated with one person-rein
of dose.
FDA advises that its cost/benefit
analysis was not conducted to establish
the PAG levels. FDA considers such use
inappropriate in part because of-the
inability to assess definitively the total"
societal impacts (positive and negative)
of such actions. Rather, the cost/benefit
analysis was used to determine whether
protective actions at the recommended
PAG's would provide a net societal
benefit TO make such an assessment, it
is necessary to place a dollar value on- a
person-rem of dose,
18. Several comments, also questioned
the appropriateness of the assumption in
the cost/benefit analysis of 23 days of
protective action, the need: to address
radionuclides other than iodine-131, and
the need to consider the impact of other
protective actions.
,The cost assessments have been
extensively revised to consider all' the
radionuclides for which derived
response levels are provided in tfie
recommendations and to incorporate
updated cost data and risk estimates
{Ref. 22). The cost/benefit analysis is
limited to the condemnation of milk and
the use of stored feed because accident
analyses indicate that the, milk pathway
is the most likely to require protective
action. Further, these two actions are
the most likely protective actions that
will be implemented,
l FDA approached the cost/benefit
analysis by calculating the
concentration of radioactivity in milk at
which the cost of taking action equals
the risk avoided by the action taken on
a daily milk intake basis. The
assessment was done on a population
basis and considered only the direct
costs of the protective actions. The
analysis indicates that, for restricting
feed to stored feed, the cost-equals-
benefit concentrations are about one-
fiftieth to one-eightieth of the Preventive
PAG level (derived peak milk
ctmcenti ation) for iodine-131, cesium-
134, and cesium-137 and about one-third
-------
47080 Fedeial Register / Vol. 47. No. 205 / Friday. October 22. 1982 / Notices
of the level for strontium-89 and
strontium-90. For condemnation of milk.
based on value at the farm, the cost-
cquals-benefit concentrations are
similar fractions of the Emergency PAG
levels (derived peak milk
concentration). If condemnation of milk
is based on retail market value, the cost-
equals-benefit concentrations are
greater by a factor of two. Thus, it
appears that protective actions at the
Preventive or Emergency PAG levels
will yield a net societal benefit.
However, in the case of strontium-89
and strontium-90, protective action will
yield a benefit only for concentrations
greater than about one-third the derived
peak values. In the case of iodine-131,
cesium-134, and cesium-137, protective
actions could be continued to avoid 95
percent of the projected radiation dose
for initial peak concentrations at the
PAG level.
Reference*
The following information has been placed
on display in the Dockets Management
Branch (HFA-305), Food and Drug
Adminlalration.Iim.4-e2, 5600 Fishers Lane.
Rockville, MD 20857. and may be seen
between 9 a.m. and 4 p.m., Monday through
Friday.
1. Federal Radiation Council. Memorandum
for the President, "Radiation Protection
Guidance for Federal Agencies." Federal
Register. August 22,1964 (29 FR 12056), and
Report No. 5 (July 1964).
2, Federal Radiation Council. Memorandum
for the President, "Radiation Protection
Guidance for Federal Agencies." Federal
Register," May 22.1965 (30 FR 6953). and
Report No. 7 (May 1965).
3. National Academy of Sciences/National
Research Council, "The Effects on Population
of Exposure to Low Levels of Ionizing
Radiation." Report of the Advisory
Committee on Biological Effects of Ionizing
Radiation (BE1R-I1I) (1980).
4. United States Nuclear Regulatory
Commission. Reactor Safety Study. WASH-
1400. Appendix VI (October 1975).
5. Ron, E. and B. Modan. "Benign and
Malignant Thyroid Neoplasms After
Childhood Irradiation for Tinea Capitis,"
Journal of the National Cancer Institute. Vol.
66. No. 1 (July 1986),
6. International Commission on
Radiological Protection (ICRP).
Recommendations of the International
Commission on Radiological Protection. ICRP
Publication 26. Annals of the ICRP. Pergamon
Press (1977).
7. Environmental Protection Agency,
"Manual of Protective Action Guides and
Protective Actions for Nuclear Incidents."
EPA 520/1-75-001, revised June 1980.
8. United Nations Scientific Committee on
the Effects of Atomic Radiation, 1977 Report.
United Nations, New York (1977).
9. Ng. Y. C., C. S. Colsher, D. J. Quinn. and
S. E. Thompson, "Transfer Coefficients for
the Prediction of the Dose to Man Via the
Forage-Cow-Milk Pathway from
Radlonuclides Released to the Biosphere,"
UCRL-51939. Lawrence Livermore
laboratory (July 15,1977).
10. International Commission on
Radiological Protection. Report of a Task
Group of Committee 2 on Reference Man,
Publication 23, p. 360. Pergamon Press.
Oxford (1974).
11. U.f Department of Agriculture,
"Household F» id Consumption Survey 1965-
1966."
12. Wellman. H. N. and R. T. Anger.
"Radioiodine Dosimetry and the Use of
Radioiodines Other Than ml in Thyroid
Diagnosis," Snminars in Nuclear Medicine.
3:356 (1971).
13. Killough. G. G., D. E. Dunning, S. R.
Bernard, and J. C. Pleasant. "Estimates of
Internal Dose Equivalent to 22 Target Organs
for Radionuclides Occurring in Routine
Releases from Nuclear Fuel-Cycle Facilities,
Vol. 1." ORNL/NUREG/TM-190. Oak Ridge
National Laboratory (June 1978).
14. National Council on Radiation
Protection and Measurements, "Cesium-137
From the Environment to Man: Metabolism
and Dose." NCRP Report No. 52, Washington
(January 15.1977).
15. International Commission on
Radiological Protection. Limits for Intakes of
Radionuclides by Workers. ICRP Publication
30. Part 1. Annals of the ICRP, Pergamon
Press (1979).
16. Papworth, D. G., and J. Vennart,
"Retention of *5r in Human Bone at Different
Ages and Resulting Radiation Doses,"
Physics in Medicine and Biology. 18:169-186
(1973).
17. Kereiakes. J. G., P. A. Feller, F. A.
Ascoli, S. R. Thomas. M. J. Gelfand. and E. L.
Saenger. "Pediatric Radiopharmaceutica!
Dosimetry" in "Radiopharmaceutical
Dosimetry Symposium." April 26-29,1976,
HEW Publication (FDA) 76-8044 (June 1976).
18. National Academy of Sciences/
National Research Council. "The Effects on
Populations of Exposure to Low Levels of
Ionizing Radiation," Report of the Advisory
Committee on Biological Effects of Ionizing
Radiation (BE1R-I) (1972).
19. National Council on Radiation
Protection and Measurements (NCRP), "Basic
Radiation Protection Criteria," NCRP Report
No. 39, Washington (1971).
20. Bogen. K. T.. and A. S. Goldin.
"Population Exposure to External Natural
Radiation Background in the United States."
ORP/SEPD-80-12. Environmental Protection
Agency, Washington. DC (April 1981).
21. Federal Interagency Task Force on
Offsite Emergency Instrumentation for
Nuclear Accidents. "Guidance on Offsite
Emergency Radiation Measurement Systems:
Phase 2, Monitoring and Measurement of
Radionuclides to Determine Dose
Commitment in the Milk Pathway,"
developed by Exxon Nuclear Idaho Co. Inc..
Idaho Falls, ID. Draft, July 1981 (to be
published by FEMA).
22. Shleien, B.. G. D. Schmidt, and R. P.
Chiacchierini, "Background for Protective
Action Recommendations; Accidental
Radioactive Contamination of Food and
Animal Feeds," September 1981, Department
of Health and Human Services. Food arid
Drug Administration. Bureau of Radiological
Health. Rockville, MD.
Pertinent background data and
information on the recommendations are
on file in the Dockets Management
Branch, and copies are available from
that office (address above).
Based upon review of the comments
received on the proposal of December
15.1978 (43 FR 58790), and FDA's further
consideration of the need to provide
guidance to State and local agencies for
use in emergency response planning in
the event that an incident results in the
radioactive contamination of human
food or animal feed, the agency offers
the following recommendations
regarding protective action planning for
human food and animal feeds:
Accidental Radioactive Contamination
of Human Food and Animal Feeds;
Recommendations for State and Local
Agencies
(a) Applicability. (1) These
recommendations are for use by
appropriate State or local agencies in
response planning and the conduct of
radiation protection activities involving
the production, processing, distribution,
and use of human food and animal feeds
in the event of an incident resulting in
the lease of radioactivity to the
environment. The Food and Drug
Administration (FDA) recommends that
this guidance be used on a case-by-case
basis to determine the need for taking
appropriate protective action in the
event of a diversity of contaminating
events, such as nuclear facility
accidents, transportation accidents, and
fallout from nuclear devices.
(2) Protective actions are appropriate
when the health benefits associated
with the reduction in exposure to be
achieved are sufficient to offset the
undesirable features of the protective
actions. The Protective Action Guides
(PAG's) in paragraph (c) of these
recommendations represent FDA's
judgment as to the level of food
contamination resulting from radiation
incidents at which protective action
should be taken to protect the public
health. Further, as provided by Federal
guidance issued by the Federal
Radiation Council, if, in a particular
situation, and effective action with low
total impact is available, initiation of
such action at a projected dose lower
than the PAG may be justifiable. If only
very high-impact action would be
effective, initiation of such action at a
projected dose higher than the PAG may
be justifiable. (See 29 FR 12056; August
22.1964.) A basic assumption in the
development of protective action
guidance is that a condition requiring
protective action is unusual and should
not be expected to occur frequently.
-------
Federal Register / Vol. 47. No. 205 / Friday. October 22, 1982 / Notices
47081
Circumstances that involve repetitive
occurrence, a substantial probability of
recurrence within a period of 1 or 2
years, or exposure from multiple sources
(such as airborne cloud and food
pathway) would require special
consideration. In such a case, the total
projected dose from the several evenls
and the total impact of the protective
actions that might be taken to avoid the
future dose from one or more of these
events may need to be considered. In
any event, the numerical values selected
for the PAG's are not intended to
authorize deliberate releases expected
to result in absorbed doses of these
magnitudes.
(3) A protective action is an action or
measure taken to avoid most of the
radiation dose that would occur from
future ingestion of foods contaminated
with radioactive materials. These
recommendations are intended for
implementation within hours or days
from the time an emergency is
recognized. The action recommended to
be taken should be continued for a
sufficient time to avoid most of the
projected dose. Evaluation of when to
cease a protective action should be
made on a case-by-case basis
considering the specific incident and the
food supply contaminated. In the case of
the pasture/cow/milk/person pathway,
for which derived "response levels" are
provided in paragraph (d) of these
recommendations, it is expected that
actions would not need to extend
beyond 1 or 2 months due to the
reduction of forage concentrations by
weathering (14-day half-life assumed).
In the case of fresh produce directly
contaminated by deposition from the
cloud, actions would be necessary at the
time of harvest. This guidance is not
intended to apply to the problems of
long-term food pathway contamination
where adequate time after the incident
is available to evaluate the public health
consequences of food contamination
using current-recommendations and the
guidance in Federal Radiation Council
(FRC) Report No. 5, July 1964 and Report
No. 7, May 1965.
(b) Definitions. (1) "Dose" is a general
term denoting the quantity, of radiation
or energy absorbed. For special
purposes it must be appropriately
qualified. In these recommendations it
refers specifically to the term "dose
equivalent."
(2) "Dose commitment" means the
radiation dose equivalent received by
an exposed individual to the organ cited
over a lifetime from a single event.
(3) "Dose equivalent" is a quantity
that expresses all radiation on a
common scale for calculating the
effective absorbed dose. It is defined as
the product of the absorbed dose in rads
and certain modifying factors. The unit
of dose equivalent is the rem.
(4) "Projected dose commitment"
means the dose commitment that would
be received in the future by individuals
in the population group .from the
contaminating event if no protective
action were taken.
(5) "Protective action" means an
action taken to avoid most of the
exposure to radiation that would occur
from future ingestion of foods
contaminated with radioactive
materials.
(6) "Protective action guide (PAG)"
means the projected dose commitment
values to individuals in the general
population that warrant protective
action following a release of radioactive
material. Protective action would be
warranted if the expected individual
dose reduction is not offset by negative
social, economic, or health effects. The
PAG does not include the dose that has
unavoidably occurred before the
assessment.
(7) "Preventive PAG" is the projected
dose commitment value at which
responsible officials should take
protective actions having minimal ipact
to prevent or reduce the radioactive
contamination of human food or animal
feeds.
(8) "Emergency PAG" is the projected
dose commitment value at which
responsible officials should isolate food
containing radioactivity to prevent its
introduction into commerce and at
which the responsible officials should
determine whether condemnation or
another disposition is appropriate. At
the Emergency PAG, higher impact
actions are justified because of the
projected health hazards.
(9) "Rad" means the unit of absorbed
dose equal to 0.01 Joule per kilogram in
any medium.
(10) "Rem" is a special unit of dose
equivalent. The dose equivalent in reins
is numerically equal to the absorbed
dose in rads multiplied by the quality
factor, the distribution factor, and any
other necessary modifying factors.
(11) "Response level" means the
activity of a specific radionuclide (i)
initially deposited on pasture; or (iij per
unit weight or volume of food or animal
feed; or (hi) in the total dietary intake
which corresponds to a particular PAG.
(c) Protective action guides (PAG's).
To permit flexibility of action for the
reduction of radiation exposure to the
public via the food pathway due to the
occurrence of a contaminating event, the
following Preventive and Emergency
PAG's for an exposed individual in the
population are adopted:
(1) Preventive PAG which is (i) 1.5
rem projected dose commitment to the
thyroid, or (ii) 0.5 rem projected dose
commitment to the whole body, bone
marrow, or any other organ.
\ (2) Emergency PAG which is (i) 15 rem
projected dose commitment to the
thyroid, or (ii) 5 rem projected dose
commitment to the whole body, bone
marrow, or any other organ.
(d) Response levels equivalent to
PAG. Although the basic PAG
recommendations are given in terms of
projected dose equivalent, it is often
more convenient to utilize specific
radionuclide concentrations upon which
to initiate protective action. Derived
response levels equivalent to the PAG's
for radionuclides of interest are:
(1) Response level for Preventive
PAG. Infant * as critical segment of
population.
, 'Newborn infant includes fetua (pregnant
women) as critical segment of population for iodine-
131. For other radionuclides, "infant" refers to child
leas than 1 year of age.
Response levels for preventive PAG
Peak Mttk Activity (microcunos/kter) ..
Total irrtak* (mnocuries)
.
13V
013
005
0015
0.09
134c.4
2
08
0 IS
4
137tt4
3
1 3
024
7
90*
0.3
018
0009
(X2
09*
g
3
0 14
2.6
•From fsltout kx)kw-131 is the only radiOKxttna of Significance with respect to milk contamination beyond ths first day. In case of a reactor accident th* cumulative intake of iodmo-133 via
milk Is about 2 percent of kxtavo-131 assuming equivalent deposition.
'Fresh weight
'Intake of ossmm via the meat/person pathway tor adults may exceed that of the mHk pathway, therefore, such levels tn milk should cause surveillance and protective actions for meat at
appropriate. H both ceskim-134 and cesium-137 ate equally present as might be expected for reactor accidents, the response levels should ba reduced by a factor of two.
-------
47082
Federal Register / Vol. 47, No. 205 / Friday. October 22. 1982 / Notices
(2} Response level for Emergency PAG. The response levels equivalent to the Emergency PAG. are presented for both
infante and adults to permit use of either level and thus assure a flexible approach to taking action in cases where exposure
of the most critical portion of the population (infants and pregnant women) can be prevented:
.
Fang* C»
Adult
20
8
0.4
7
88
Intent*
80
30
1.4
26
w
Adult
1600
700
30
400
'Newborn Mai* mduoes tetua (pregnant women) a* critical segment at population lor wdine-131.
'"Want" nlan to cMd fete than 1 year of age.
'From tolout udine-131 • In* only radioiodine of significance with respect to milk contamination beyond the first day. In case of a reactor accident (he cumulative intake of iodine-133 via
m* • about 2 percent of todme-131 assuming equivalent deposition.
•Fresh weight. ^^
•Intake of cnlum via the meat/per*on pathway for adults may exceed that of the mitk pathway: therefore, such levels in milk should came surveillance and protective actions for meat at
appropriate, N both ceuum-134 and ceswm-137 are equaUy present, as might be expected tor reactor accidents, the response' levels should be reduced by a factor ol 2.
(e) Implementation. When using the
PAG's and associated response levels
for response planning or protective
actions, the following conditions should
be followed:
{i.} Sped fie food items. To obtain the
response level (microcurie/kilogram)
equivalent to the PAG for other specific
foods, it is necessary to weigh the
contribution of the individual food to the
•total dietary intake; thus.
Response Level •
. Total intake (microcuries)
' Consumption (kilograms)
Where: Total intake (microcuries) for the
appropriate PAG and radionuclide is
given in paragraph (d) of these
recommendations
and
Consumption U the product of the average
daily consumption specified in paragraph
(e)(l)(i) of these recommendations and
the daya of intake of the contaminated
food as specified in paragraph (e](l)(ii) of
these recommendations.
(i) The daily consumption of specific
foods in kilograms per day for the
general population is given in the
following table:
Food
Me*, oaem. ehnia. ice cream'
Fato,o>s
Hour. cem*l_
Bakery products..
Meet.
Poultry
fi«nand8h*»Bjn~i
Egg*.
Sugar, tirupa, honey, molasse*. etc.-
•I potato
Vegetable*, freed (excluding potato**)..
Vejetabtea, canoed, trtaen, dried
Vegetables, Juice (single atreng*))
FruN.lrear).
Fruit, canned, frozen, dried..
TnM, Juice (stogie sowgth).
Average
con-
sumption
for the
"So*
(Wo-
gram/
day)
.570
.055
.091
.ISO
.220
.055
.023
.055
.073
.105
.145
.077
.009
.165
.036
.045
Food
Other beverages (soft drinks, coffee, alcoholic)..
Soup and gravies (mostly condensed) .
Nuts and peanut butter.
Total..
Average
con-
sumption
for the
general
popula-
tion
(Kilo-
gram/
day)
.180
.036
.009
2.099
'Expressed aa calcium equrvaJerrt; thai is, the quantity ol
whole fluid milk to which dairy products are equivalent in
calcium content
(U) Assessment of the effective days
of intake should consider the specific
food, the population involved, the food
distribution system, and the
radionuclide. Whether the food is
distributed to the retail market or
produced for home use will significantly
affect the intake in most instances.
Thus, while assessment of intake should
be on a case-by-case basis, some
general comments may be useful in
specific circumstances.
[a] For short half-life radionuclides,
radioactive decay will limit the
ingestion of radioactive materials and
the effective "days of intake". The
effective "days of intake" in this case is
1.44 times the radiological half-life. For
iodine-131 (half-life—8.05 days), the
effective "days of intake" is, thus, 11
days.
(b) Where the food product is being
harvested on a daily basis, it may be
reasonable to assume reduction of
contamination due to weathering. As an
initial assessment, it may be appropriate
to assume a 14-day weathering half-life
(used for forage in pasture/cow/milk
pathway) pending further evaluation. In
this case, the effective "days of intake"
is 20 days. A combination of radioactive
decay and weathering would result in
an effective half-life for iodine-131 of 5
days and reduce the "days of intake" to
7 days.
(c) In the case of a food which is sold
in the retail market, the effective "days
of intake" would probably be limited by
the quantity purchased at a given time.
For most food, especially fresh produce,
this would probably be about a 1 week
supply. In some cases, however, larger
quantities would be purchased for home
canning or freezing. For most foods and
members of the public, an effective
"days of intake" 30 days is probably
conservative.
(iii) For population groups having
significantly different dietary intakes, an
appropriate adjustment of dietary
factors should be made.
(2) Radionuclide mixtures. If a
mixture of radionuclides is present, the
sum of all the ratios of the concentration
of each specific radionulide to its
specific response level equivalent to the
PAG should be less than one.
(3) Other radionuclides. The response
level for the Preventive and Emergency
PAG for other radionuclides should be
calculated from dose commitment
factors available in the literature
(Killough, G. G.. et al., ORNL/NUREG/
-TM-190 (1978) (adult only), and U.S.
Nuclear Regulatory Commission Reg.
Guide 1.109 (1977)).
(4) Other critical organs. Dose
commitment factors in U.S. Nuclear
Regulatory Commission Reg. Guide 1.169
(1977). refer to bone rather than bone
marrow dose commitments. For the
purpose of these recommendations, dose
commitment to the bone marrow is
considered to be 0.3 of the bone dose
commitment. This is based on the ratio
of dose rate per unit activity in the bone
marrow to dose rate per unit activity in
a small tissue-filled cavity in bone and
assumes that strontium-90 is distributed
only in the mineral bone (Spiers, F. W.,
et al., in "Biomedical Implications of
Radiostronrium Exposure," AEC
Symposium 25 (1972). The ratio for
strontium-89 is the same because the
mean particle energies are similar (0.56
MeV (megaelectronvolts)). Situations
could arise in which an organ other than
those discussed in this paragraph could
-------
Federal Register / Vol. 47. No. 205 / Friday. October 22.1982 / Notices 47088
be considered to be the organ receiving
the highest dose per unit intake. In the
case of exposure via the food chain,
depending on the radionuclide under
consideration, the gastrointestinal tract
could be the primary organ exposed.
The references cited in paragraph (e](3)
of these recommendations contain dose
commitment factors for the following
organs: bone, kidneys, liver, ovaries,
spleen, whole body, and gastrointestinal
tract
(5) Prompt notification of State and
local agencies regarding the occurrence
of an incident having potential public
health consequences is of significant
value in the implementation of effective
protective actions. Such notification is
particularly important for protective
actions to prevent exposures from the
airborne cloud but is also of value for
food pathway contamination.
Accordingly, this protective action
guidance should be incorporated in
State/local emergency plans which
provide for coordination with nuclear
facility operators including prompt
notification of accidents and technical
communication regarding public health
consequences and protective action.
(f) Sampling parameter. Generally,
sites for sample collection should be the
retail market the processing plant, and
the farm. Sample collection at the milk
processing plant may be more effcient in
determining the extent of the food
pathway contamination. The geographic
area where protective actions are
implemented should be based on
considerations of the wind direction and
atmospheric transport, measurements by
airborne and ground survey teams of the
radioactive cloud and surface
deposition, and measurements in the
food pathway.
(g) Recommended methods of
analysis. Techniques for measurement
of radionuclide concentrations should
have detection limits equal to or less
than the response levels equivalent to
specific PAG. Some useful methods of
radionuclide analysis can be found in:
(1) Laboratory Methods-—"HASL
Procedure Manual," edited by John H.
Harley. HASL 300 ERDA. Health and
Safety Laboratory, New York, NY, 1973;
"Rapid Methods for Estimating Fission
Product Concentratioes in Milk," U.S.
Department of Health, Education, and
Welfare, Public Health Service
Publication No. 999-R-2, May 1963;
"Evaluation of Ion Exchange Cartridges
for Field Sampling of Iodine-131 in
Milk," Johnson, R. H. and T. C. Reavy,
Nature, 208, (5012): 750-752, November
20,196S; and
(2) Field Methods—Kearny, C. H.,
ORNL 4900, November 1973; Distenfeld,
C. and J. Klemish. Brookhaven National
Laboratory, NUREG/CR-0315,
December 1978; and International
Atomic Eftergy Agency, "Environmental
Monitoring in Emergency Situations',"
1966. Analysis need not be limited to
these methodologies but should provide
comparable results. Action should not
be taken without verification of the
analysis. Such verification might include
the analysis of duplicate samples,
laboratory measurements, sample
analysis by other agencies, sample
analysis of various environmental
media, and descriptive data on
radioactive release.
(h) Protective actions. Actions are
appropriate when the health benefit
associated with the reduction in dose
that can be achieved is considered to
offset the undesirable health, economic,
and social factors. It is the intent of
these recommendations that, not only
the protective actions cited for the
Emergency PAG be initiated when the
equivalent response levels are reached,
but also that actions appropriate at the
Preventive PAG be considered. This has
the effect of reducing the period of time
required during which die protective
action with the greater economic and
social impact needs to be taken, FBA
recommends that once one or more
protective actions are initiated, the
action or actions continue for a
•sufficient time to avoid most of the
projected dose. There is a longstanding
FDA policy that the purposeful blending
of adulterated food with unadulterated
food is a violation of the Federal Food,
Drag, and Cosmetic Act. The following
protective actions should be considered
for implementation when the projected
dose equals or exceeds the appropriate
PAG:
(1J Preventive PAG. (i) For pasture: (a]
Removal of lactating dairy cows from
contaminated pasturage and
substitution of uncontarninated stored
feed.
[b] Substitute source of
uncontaminated water.
pi} For milk: (a) Withholding of
contaminated milk from the market to
allow radioactive decay of short-lived
radionuclides. This may be achieved by
storage of frozen fresh milk, frozen
concentrated milk, or frozen
concentrated milk products.
{b) Storage for prolonged times at
reduced temperatures also is feasible
provided ultrahigh temperature
pasteurization techniques are employed
for processing (Finley, R. D., H. B.
Warren, and R. E. Hargrove, "Storage
Stability of Commercial MlVt," foumal
of Milk and Food Technology,
31(12):382-387, December 1968).
(c) Diversion of fluid milk for
production of dry whole milk, nonfat dry
milk, butter, cheese, or evaporated milk.
(iii) For fruits and vegetables: (a)
Washing, brushing, scrubbing, or peeling
to remove surface contamination.
; [b) Preservation by canning, freezing,
and dehydration or storage to permit
radioactive decay of short-lived
radionuclides.
(iv) For grains: (a Milling and (b)
polishing.
• (v) For other food products, processing
to remove surface contamination,
(vi) For meat and meat products,
intake of cesium-134 and cesium-137 by
an adult via the' meat pathway may
exceed that of the milk pathway;
therefore, levels of cesium in milk
approaching the "response level" should
cause surveillance and protective
actions for meat as appropriate.
: (vii)For animal feeds' other than
pasture, action should be on a case-by-
case basis taking into consideration the
relationship between the radionuclide
concentration in the animal feed and the
concentration of the radionuclide in
human food. For hay and silage fed to
lactating cows, the concentration should
not exceed that equivalent to the
recommendations for pasture.
(2) Emergency PAG. Responsible
officials should isolate food containing
radioactivity to prevent its introduction
into commerce and determine whether
condemnation or another disposition is
appropriate. Before taking this action,
the following factors should be
considered:
(i) The availability of other possible
protective actions discussed in
paragraph (h){lj of these
recommendations.
(ii) Relative proportion of the total
diet by weight represented by the item
in question.
(iiij The importance of1 the particular
food in nutrition and the availability of
uncontaminated food or substitutes
having the same nutritional properties.
(iv) The relative contribution of other
foods and other radionuclides to the
total projected dose.
(v) The time and effort required to
effect corrective action.
This notice is issued under the Public
Health Service Act (sees. 301, 310, 311,
58 Stat. 691-893 as amended, 88 Stat. 371
(42 U.S.C. 241, 242o, 243)) and under
authority delegated to the Commissioner
of Food and Drugs (21 CFR 5.10).
: Dated: October 11. 19B2,
Arthur Hull Hayes, Jr.,
Commissioner of Food and Drugs.
|FR Doc. B2-2BSBS Filed !&-21-«: 8:4S am|
' BILLING CODE 4180-4J1-II
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CHAPTER 4
Protective Action Gttides for the Intermediate Phase
(Deposited Radioactive Materials)
4.1 Introduction
Following a nuclear incident it
may be necessary to temporarily
relocate the public from areas where
extensive deposition of radioactive
materials has occurred until
decontamination has taken place. This
chapter identifies the levels of
radiation exposure which indicate when
relocation from contaminated property
is warranted.
The period addressed by this
chapter is denoted the "intermediate
phase." This is arbitrarily defined as
the period beginning after the source
and releases have been brought under
control and environmental
measurements are available for use as
a basis for decisions on protective
actions and extending until these
protective actions are terminated. This
phase may overlap the early and late
phases and may last from weeks to
many months. For the purpose of dose
projection, it is assumed to last for one
year. Prior to this period protective
actions will have been taken based
upon the PAGs for the early phase. It
is assumed that decisions will be made
during the intermediate phase
concerning whether particular areas or
properties from which persons have
been relocated will be decontaminated
and reoccupied, or condemned and the
occupants permanently relocated.
These actions will be carried out during
the late or "recovery" phase.
Although these Protective Action
Guides (PAGs) were developed based
on expected releases of radioactive
materials characteristic of reactor
incidents, they may be applied to any
type of incident that can result in
long-term exposure of the public to
deposited radioactivity.
PAGs are expressed in terms of
the projected doses above which
specified protective actions are
warranted. In the case of deposited
radioactivity, the major relevant
protective action is relocation. Persons
not relocated (i.e., those in less
contaminated areas) may reduce their
dose through the application of simple
decontamination techniques and by
spending more time than usual in low
exposure rate areas (e.g., indoors).
The PAGfe should be considered
mandatory only for use in planning,
e.g., in developing radiological
emergency response plans. During an
incident, because of unanticipated local
conditions and; constraints, professional
judgment by responsible officials will
be required , in their application.
Situations can be envisaged, where
contamination from a nuclear incident
4-1
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occurs at a site or time in which
relocation of the public, based on the
recommended PAGs, would be
impracticable. Conversely, under some
conditions, relocation may be quite
practicable at projected doses below the
PAGs. These situations require
judgments by those responsible for
protective action decisions at the time
of the incident. A discussion of the
implementation of these PAGs is
provided in Chapter 7.
The PAGs for relocation specified
in this chapter refer only to estimates
of doses due to exposure during the
first year after the incident. Exposure
pathways include external exposure to
radiation from deposited radioactivity
and inhalation of resuspended
radioactive materials. Protective
Action Guides for ingestion exposure
pathways, which also apply during the
intermediate phase, are discussed
separately in Chapter 3.
Individuals who live in areas
contaminated by long-lived
radionuelides may be exposed to
radiation from these materials, at a
decreasing rate, over the entire time
that they live in the area. This would
be the case for those who are not
relocated as well as for persons who
return following relocation. Because it
is usually not practicable, at the time
of a decision to relocate, to calculate
the doses that might be incurred from
exposure beyond one year, and because
different protective actions may be
appropriate over such longer periods of
time, these doses are not included in
title dose specified in the PAGs for
relocation.
4.1.1 Exposure Pathways
The principal pathways for
exposure of the public occupying
locations contaminated by deposited
radioactivity are expected to be
exposure of the whole body to external
gamma radiation from deposited
radioactive materials (groundshine)
and internal exposure from the
inhalation of resuspended materials.
For reactor incidents, external gamma
radiation is expected to be the
dominant source.
Almost invariably relocation
decisions will be based on doses from
the above pathways. (However, in rare
cases where food or drinking water is
contaminated to levels above the PAG
for ingestion, and its withdrawal from
use will create a risk from starvation
greater than that from the radiation
dose, the dose from ingestion should be
added to the dose from the above
pathways.) PAGs related specifically to
the withdrawal of contaminated food
and water from use are discussed in
Chapter 3.
Other potentially significant
exposure pathways include exposure to
beta radiation from surface
contamination and direct ingestion of
contaminated soil. These pathways are
not expected to be controlling for
reactor incidents (AK-89).
4.1.2 The Population Affected
The PAGs for relocation are
intended for use in establishing the
boundary of a restricted zone within an
4-2
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area that has been subjected to
deposition of radioactive materials.
During their development,
consideration was given to the higher
risk of effects on health to children and
fetuses from radiation dose and the
higher risk to some other population
groups from relocation. To avoid the
complexity of implementing separate
PAGs for individual members of the
population, the relocation PAG is
established at a level that will provide
adequate protection for the general
population.
Persons residing in contaminated
areas outside the restricted zone will
be at some risk from radiation dose.
Therefore, guidance on the reduction of
dose during the first year to residents
outside this zone is also provided. Due
to the high cost of relocation, it is more
practical to reduce dose in this
•population group by the early
application of simple, low-impact,
protective actions other than by
relocation.
4.2 The Protective Action Guides for
Deposited Radioactivity
PAGs for protection from deposited
radioactivity during the intermediate
phase are summarized in Table 4-1.
The basis for these values is presented
in detail in Appendix E. In summary,
relocation is warranted when the
projected sum of the dose equivalent
from external gamma radiation and the
committed effective dose equivalent
from inhalation of resuspended
radionuclides exceeds 2 rem in the first
year. Relocation to avoid exposure of
the skin to beta radiation is warranted
at 50 times the numerical value of the
relocation PAG for effective dose
equivalent.
Persons who are not relocated, i.e.,
those in areas that receive relatively
small amounts of deposited radioactive
material, should reduce their exposure
by the application of other measures.
Possible dose reduction techniques
range from the simple processes of
scrubbing and/or flushing surfaces,
soaking or plowing of soil, removal and
disposal of small spots of soil found to
be highly contaminated (e.g., from
settlement of water), and spending
more time than usual in lower
exposure rate areas (e.g., indoors), to
the difficult, and time-consuming
processes of removal, disposal, and
replacement of" contaminated surfaces.
It is anticipated that simple processes
will be most appropriate for early
application. Many can be carried out
by residents themselves with support
from response officials for assessment
of the levels of contamination, guidance
on appropriate actions, and disposal of
contaminated materials. Due to the
relatively low cost and risk associated
with these protective actions, they may
be justified as ALARA measures at low
dose levels. It is, however,
recommended that response officials
concentrate their initial efforts in areas
where the projected dose from the first
year of exposure exceeds 0.5 rem. In
addition, first priority should be given
to cleanup of residences of pregnant
women who may exceed this criterion.
4-3
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Table 4-1 Protective Action Guides for Exposure to Deposited Radioactivity
During the Intermediate Phase of a Nuclear Incident
Protective
Action
PAG (projected
dose)*
Comments
Relocate the general
population.13
Apply simple dose
reduction techniques.0
>2 rem
<2 rem
Beta dose to skin may be
up to 50 times higher
These protective actions
should be taken to reduce
doses to as low as
practicable levels.
The projected sum of effective dose equivalent from external gamma radiation and committed
effective dose equivalent from inhalation of resuspended materials, from exposure or intake during
the first year. Projected dose refers to the dose that would be received in the absence of shielding
from structures or the application of dose reduction techniques. These PAGs may not provide
adequate protection from some long-lived radionuclides (see Section 4.2.1).
^Persons previously evacuated from areas outside the relocation zone defined by this PAG may
return to occupy their residences. Cases involving relocation of persons at high risk from such
action (e.g., patients under intensive care) should be evaluated individually.
'Simple dose reduction techniques include scrubbing and/or flushing hard surfaces, soaking or
plowing soil, minor removal of soil from spots where radioactive materials have concentrated, and
spending more time than usual indoors or in other low exposure rate areas.
4.2.1 Longer Term Objectives of the
Protective Action Guides
It is an objective of these PAGs to
assure that 1) doses in any single year
after the first will not exceed 0.5 rem,
and 2) the cumulative dose over 50
years (including the first and second
years) will not exceed 5 rem. For
source terms from reactor incidents,
the above PAG of 2 rem projected dose
in tide first year is expected to meet
both of those objectives through
radioactive decay, weathering, and
normal part time occupancy in
structures. Decontamination of areas
outside the restricted area may be
required during the first year to meet
these objectives for releases consisting
primarily of long-lived radionuclides.
For situations where it is impractical to
meet these objectives though
decontamination, consideration should
be given to relocation at a lower
projected first year dose than that
specified by the relocation PAG.
4-4
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After the population has been
protected in accordance with the PAGs
for relocation, return for occupancy of
previously restricted areas should be
governed on the basis of Recovery
Criteria as presented in Chapter 8.
Projected dose considers exposure
rate reduction from radioactive decay
and, generally, weathering. When one
also considers the anticipated effects of
shielding from partial occupancy in
homes and other structures, persons
who are not relocated should receive a
dose substantially less than the
projected dose. For commonly assumed
reactor source terms, we estimate that
2 rem projected dose in the first year
will be reduced to about 1.2 rem by
this factor. The application of simple
decontamination techniques shortly
after the incident can be assumed to
provide a further 30 percent or more
reduction, so that the maximum first
year dose to persons who are not
relocated is expected to be less than
one rem. Taking account of decay rates
assumed to be associated with releases
from nuclear power plant incidents
(SN-82) and shielding from partial
occupancy and weathering, a projected
dose of 2 rem in the first year is likely
to amount to an actual dose of 0.5 rem
or less in the second year and 5 rem or
less in 50 years. The application of
simple dose reduction techniques would
reduce these doses further. Results of
calculations supporting these
projections are summarized in Table
E-6 of Appendix E.
4.2.2 Applying the Protective Action
Guides for Relocation
Establishing the boundary of a
restricted zone may result in three
different types of actions:
1. Persons who, based on the PAGs for
the early phase of a nuclear incident
(Chapter 2), have already been
evacuated from an area which is now
designated as a restricted zone must
be converted to relocation status.
2. Persons not previously evacuated
who reside inside the restricted zone
should relocate.
3. Persons who normally reside
outside the restricted zone, but were
previously evacuated, may return, A
gradual return is recommended, as
discussed in Chapter 7.
Small adjustments to the boundary
of the restricted zone from that given
by the PAG may be justified on the
basis of difficulty or ease of
implementation. For example, the use
of a convenient natural boundary could
be cause for adjustment of the
restricted zone. However, such
decisions should be supported by
demonstration that exposure rates to
persons not relocated can be promptly
reduced by ! methods other than
relocation to meet the PAG, as well as
the longer term dose objectives
addressed in Section 4.2.1.
Reactor ; incidents involving
releases of major portions of the core
inventory under adverse atmospheric
conditions can, be postulated for which
4-5
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large areas would have to be restricted
•under these PAGs, As the affected
land area increases, they wil become
more difficult and costly to implement,
especially in densely populated areas,
For situations where implementation
becomes impracticable or impossible
(e.g., a large city), informed judgment
must be exercised to assure priority of
protection for individuals in areas
having the highest closure rates. In
such situations, the first priority for
any area should be to reduce dose to
pregnant women.
References
AE-89 Aaberg, Rosanne, Evaluation of Skin
and Ingestion Exposure Pathways. 1PA
520/1-89-016. U.S. Environmental Protection
Agency, Washington, (1989).
EP-87 U.S. Environmental Protection Agency,
Radiation Protection Guidance to Federal
Agencies for Occupational Exposure. Federal
Begister. 52, 2822; January 27, 1987.
SN-82 Sandia National Laboratory. Technical
Guidance for Siting Criteria Development,
NUEEG/CR-2239. U.S. Nuclear Regulatory
Commission, Washington, (1982).
4.3 Exposure limits for Persons
Keentering the Restricted Zone
Individuals who are permitted to
reenter a restricted zone to work, or for
other justified reasons, will require
protection from radiation. Such
individuals should enter the restricted
zone under controlled conditions in
accordance with dose limitations and
other procedures for control of
occupationally-exposed workers
(EP-87). Ongoing doses received by
these individuals from living in a
contaminated area outside the
restricted zone need not be included as
part of this dose limitation applicable
to workers. In. addition, dose received
previously from the plume and
associated groundshine, during the
early phase of the nuclear incident,
need not be considered.
4-6
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CHAPTERS
Implementing the Protective Action Guides
for the Early Phase
5.1 Introduction
This chapter provides general
guidance for implementing the
Protective Action Guides (PAGs) set
forth in Chapter 2. In particular, the
objective is to provide guidance for
estimating projected doses from
exposure to an airborne plume of
radioactive material, and for choosing
and implementing protective actions.
Following an incident which has the
potential for an atmospheric release of
radioactive material, the responsible
State and/or local authorities will need
to decide whether offsite protective
actions are needed and, if so, where
and when they should be implemented.
These decisions will be based primarily
on (a) the potential for releases, (b)
projected doses as a function of time at
various locations in the environment,
and (c) dose savings and risks
associated with various protective
actions.
Due to the wide variety of nuclear
facilities, incidents, and releases that
could occur, it is not practical to
provide specific implementing guidance
for all situations. Examples of the
types of sources leading to airborne
releases that this guidance may be
applied to are nuclear power reactors,
uranium fuel cycle facilities, nuclear
weapons facilities, radiopharmaceutical
manufacturers and users, space vehicle
launch and reentry, and research
reactors. For many specific
applications, however, it will be
appropriate to develop and use
implementing procedures that are
designed for use on a case-by-case
basis.
Dose conversion factors (DCF) and
derived response levels (DRL) are
provided for radionuclides that are
most likely to be important in an
incident involving an airborne release
of radioactive materials. DCFs and
DRLs for radionuclides not listed may
be developed from the sources refer-
enced in the tables. The values
provided here are the best currently
available. However, as new infor-
mation is developed these values may
change. This chapter will be revised
from time to time to reflect such
changes.
5.2 Initial Response and Sequence of
Subsequent Actions
In the case of an atmospheric
release, the protective actions which
may be required are those which pro-
tect the population from inhalation of
radioactive materials in the plume,
from exposure to gamma radiation
5-1
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from the plume, and from short-term
exposure to radioactive materials
deposited on the ground. For releases
which contain a large amount of pure
beta emitters, it may also be necessary
to consider protective action to avoid
doses to the skin from radioactive
material deposited on the skin and
clothing.
The early phase can be divided into
two periods: (a) the period immed-
iately following the start of an incident
(possibly before a release has occurred),
when little or no environmental data
are available to confirm the magnitude
of releases, and (b) the subsequent
period, when environmental or source
term measurements permit a more
accurate assessment of projected doses.
During the first period, speed in
completing such actions as evacuating,
sheltering, and controlling access may
be critical to minimizing exposure.
Environmental measurements made
during this period may have limited
use because of the lack of availability
of significant data and uncertainty
about changes in environmental
releases of radioactive material from
their sources. In. the case of a facility,
for example, the uncertainty might be
due to changes in pressure and
radionuclide concentrations within the
structures from which the plume is
being released. Therefore, it is
advisable to initiate early protective
actions in a predetermined manner
that is related to facility conditions.
This will normally be carried out
through recommendations provided by
the facility operator. During the
second period, when environmental
levels are known, these actions can be
adjusted as necessary.
For an incident at a facility
involving significant potential for an
atmospheric release with offsite
consequences, the following sequence of
actions is appropriate:
1. Notification of State and/or local
authorities by the facility operator that
conditions are such that a release is
occurring, or could occur with offsite
consequences. For severe incidents
(e.g., general emergencies) the operator
should provide protective action
recommendations to State and local
authorities.1
2. For emergencies with the potential
for offsite consequences, immediate
evacuation (and/or sheltering) of
populations in predesignated areas
without waiting for release rate
information or environmental
measurements.
3. Monitoring of facility conditions,
release rates, environmental concentra-
tions, and exposure rates.
*In the ease of commercial nuclear power
plants, fuel facilities and certain material
facilities licensed by the NRG, regulations (NR-
89) require that the facility operator have the
capability to notify predesignated State and/or
local authorities within 15 minutes of any
emergency declaration. The initial notification
message to State and/or local officials for any
General Emergency declaration must include a
protective action recommendation.
5-2
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4. Estimation of offsite consequences
(e.g., calculation of the plume
centerline dose rates and projected
doses at various distances downwind
from the release point).
5. Implementation of protective
actions in additional areas if needed.
6. Decisions to terminate existing
protective actions should include, as a
minimum, consideration of the status
of the plant and the PAGs for
relocation (Chapter 4). (Withdrawal of
protective actions from areas where
they have already been implemented is
usually not advisable during the early
phase because of the potential for
changing conditions and confusion.)
For other types of incidents the
sequence of actions may vary in details,
depending on the specific emergency
response plan, but in general the
sequence and general reporting
requirements will be the same.
5.2.1 Notification
The nuclear facility operator or
other designated individual should
provide the first notification to State
and/or local authorities that a nuclear
incident has occurred. In the case of
an incident with the potential for
offsite consequences, notification of
State and local response organizations
by a facility operator should include
recommendations, based on plant
conditions, for early evacuation and/or
sheltering in predesignated areas.
Early estimates of the various
components of projected doses to the
population at the site boundary, as well
as at more distant locations, along with
estimated time frames, should be made
as soon as the relevant source or
release data become available.
Emergency response planners should
make arrangements with the facility
operator to assure that this
information will be made available on
a timely basis and that dose projections
will be provided in units that can be
directly compared to the PAGs.
Planners should note that the toxic
chemical hazard is greater than the
radiation hazard for some nuclear
incidents, e.g. a uranium hexafluoride
release.
For some incidents, such as re-entry
of satellites or an incident in a foreign
country, notification is most likely to
occur through the responsible Federal
agency, most commonly the
Environmental Protection Agency or
the National Aeronautics and Space
Administration. In such cases
projections of dose and
recommendations to State and local
officials for protective actions will be
made at the Federal level, under the
Federal Radiological Emergency
Response Plan (FE-85).
5.2,2 Immediate Protective Action
Guidance for developing emergency
response plans for implementation of
immediate protective actions for
incidents at commercial nuclear power
plants is contained in NUREG-0654
(NR-80). Planning elements for
9
5-3
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incidents at other types of nuclear
facilities should be developed using
similar considerations. Information on
the offsite consequences of accidents
that can occur at commercial fuel cycle
and material facilities licensed by the
NRG can be found in NUREG-1140
(NR-88). The "Planning Basis for the
Development of State and Local
Government Radiological Emergency
Response Plans in Support of Light
Water Nuclear Power Plants" (NR-78)
recommends that States designate an
emergency planning zone (EPZ) for
protective action for plume exposure
(see Chapter 2). Within this zone, an
area should be predesignated for
immediate response based on specified
plant conditions prior to a release, or,
given a release, prior to the availability
of information on quantities of
radioactive materials released. The
shape of this area will depend on local
topography and political and other
boundaries. Additional areas in the
balance of the EPZ, particularly in the
downwind direction, may also require
evacuation or sheltering, as determined
by dose projections. The size of these
areas will be based on the potential
magnitude of the release, and of an
angular spread determined by
meteorological conditions and any other
relevant factors.
The predesignated areas for
immediate protective action may be
reserved for use only for the most
severe incidents and where the facility
operator cannot provide a quick
estimate of projected dose based on
actual releases. For lesser incidents, or
if the facility operator is able to provide
prompt offsite dose projections, the
area for immediate protective action
may be specified at the time of the
incident, in lieu of using a
predesignated area.
Such prompt offsite dose projections
may be possible when the facility
operator can estimate the potential
offsite dose, based on information at
the facility, using relationships
developed during planning that relate
abnormal plant conditions and
meteorological conditions to potential
offsite doses. After the release starts
and the release rate is measurable
and/or when plant conditions or
measurements can be used to estimate
the characteristics of the release and
the release rate as a function of time,
then these factors, along with
atmospheric stability, windspeed, and
wind direction, can be used to estimate
integrated concentrations of radioactive
contamination as a function of location
downwind. Although such projections
are useful for initiating protective
action, the accuracy of these methods
for estimating projected dose will be
uncertain prior to confirmatory field
measurements because of unknown or
uncertain factors affecting
environmental pathways, inadequacies
of computer modeling, and uncertainty
in the data for release terms.
5.3 The Establishment of Exposure
Patterns
During and immediately following
the early response to a nuclear
incident, sufficient environmental
5-4
-------
measurements are unlikely to be
available to project doses accurately.
Doses must be projected using initial
environmental measurements or
estimates of the source term, and using
atmospheric transport previously
observed under similar meteorological
conditions. These projections are
needed to determine whether protective
actions should be implemented in
additional areas during the early
phase.
Source term measurements, or
exposure rates or concentrations
measured in the plume at a few
selected locations, may be used to
estimate the extent of the exposed area
in a variety of ways, depending on the
types of data and computation methods
available. The most accurate method
of projecting doses is through the use of
an atmospheric diffusion and transport
model that has been verified for use at
the site in question. A variety of
computer software can be used to
estimate exposures in real time, or to
extrapolate a series of previously-
prepared isopleths for unit releases
under various meteorological
conditions. The latter can be adjusted
for the estimated source magnitude or
environmental measurements at a few
locations during the incident. If the
model projections have some semblance
of consistency with environmental
measurements, extrapolation to other
distances and areas can be made with
greater confidence. If projections using
a sophisticated site-specific model are
not available, a simple, but crude,
method is to measure the plume cen-
terline exposure rate2 at ground level
(approximately one meter height) at a
known distance downwind of the
release point and then to calculate
exposure rates at other downwind
locations by assuming that the plume
centerline exposure rate is a known
function of the distance from the
release point.
The following relationship can be
used for this calculation:
D2 = D! (R1/R2)y ,
where Dj and D2 are measurements of
exposure rates at the centerline of the
plume at distances Rx and R2,
respectively, and y is a constant that
depends on atmospheric stability. For
stability classes A and B, y = 2; for
stability classes C and D, y = 1.5; and
for stability classes B and F, y = 1.
Classes A and B (unstable) occur with
light winds and strong sunlight, and
classes E and F (stable) with light
winds at night. Classes C and D
generally occur with winds stronger
than about 10 mph. This method of
extrapolation is risky because the
measurements available at the
reference distance may be
unrepresentative, especially if the
plume is aloft and has a looping
2The centerline exposure rate can be
determined by traversing the plume at a point
sufficiently far downwind that it has stabilized
(usually more than one mile from the release
point) while taking continuous exposure rate
measurements.
5-5
-------
behavior. In. the case of an elevated
plume, the ground level concentration
increases with distance from the
source, and then decreases, whereas
any high, energy gamma radiatio: "om
the overhead cloud continuously
decreases with distance. For these
reasons, this method of extrapolation
will perform best for surface releases or
if the point of measurement for an
elevated release is sufficiently distant
from the point of release for the plume
to have expanded to ground level
(usually more than one mile). The
accuracy of this method wiE be
improved by the use of measurements
from many locations averaged over
time.
5.4 Dose Projection
The PAGs set forth in Chapter 2
are specified in terms of the effective
dose equivalent. This dose includes
that due to external gamma exposure
of the whole body, as well as the
committed effective dose equivalent
from inhaled radionuclides. Guidance
is also provided on protective action
levels for the thyroid and skin, in
terms of the committed dose equivalent
to these organs. Further references to
effective or organ dose equivalent refer
to these two quantities, respectively.
Methods for estimating projected doses
for of these forms of exposure are
discussed below. These require
knowledge of, or assumptions for, the
intensity and duration of exposure and
make use of standard assumptions on
the relation, for each radioisotope,
between exposure and dose. Exposure
and dose projections should be based
on the best estimates available. The
methods and models used here may be
modified as necessary for specific sites
to achieve improved accuracy.
5.4.1 Duration of Exposure
The projected dose for comparison
to the early phase PAGs is normally
calculated for exposure during the first
four days following the projected (or
actual) start of a release. The objective
is to encompass the entire period of
exposure to the plume and to deposited
material prior to implementation of any
further, longer-tarm protective action,
such as relocation. Four days is chosen
here as the duration of exposure to
deposited materials during the early
phase because, for planning purposes;
it is a reasonable estimate of the time
needed to make measurements, reach
decisions, and prepare to implement
relocation. However, officials at the
site at the time of the emergency may
decide that a, different time is more
appropriate. Corresponding changes to
the dose conversion factors found in
tables in Section 5.4.2 will be needed if
another exposure period is selected.
Protective actions are taken to
avoid or reduce projected doses. Doses
incurred before the start of the
protective action being considered
should not normally be included in
evaluating the need for protective
action. Likewise, doses that may be
incurred at later times than those
affected by the specific protective
action should not be included. For
5-6
-------
example, doses which, may be incurred
through ingestion pathways or
long-term exposure to deposited
radioactive materials take place over a
different, longer time period.
Protective actions for such exposures
should be based on guidance addressed
in other chapters.
The projected dose from each
radionuclide in a plume is proportional
to the time-integrated concentration of
the radionuclide in the plume at each
location. This concentration will
depend on the rate and the duration of
the release and meteorological
conditions. Release rates will vary
with time, and this time-dependence
cannot usually be predicted accurately.
In the absence of more specific
information, the release rate may be
assumed to be constant.
Another factor affecting the
estimation of projected dose is the
duration of the plume at a particular
location. For purposes of calculating
projected dose from most pathways,
exposure will start at a particular
location when the plume arrives and
end when the plume is no longer
present, due either to an end to the
release, or a change in wind direction.
Exposure from one pathway (whole
body exposure to deposited materials)
will continue for an extended period.
Other factors such as the aerodynamic
diameter and solubility of particles,
shape of the plume, and terrain may
also affect estimated dose, and may be
considered on a site- and/or source-
specific basis.
Prediction of time frames for
releases is difficult because of the wide
range associated with the spectrum of
potential incidents. Therefore,
planners should consider the possible
time periods between an initiating
event and arrival of a plume, and the
duration of releases in relation to the
time needed to implement competing
protective actions (i.e., evacuation and
sheltering). Analyses of nuclear power
reactors (NR-75) have shown that some
incidents may take several days to
develop to the point of a release, while
others may begin as early as one-half
hour after an initiating event.
Furthermore, the duration of a release
may range from less than one hour to
several days, with the major portion of
the release usually occurring within
the first day.
Radiological exposure rates are
quite sensitive to the wind speed. The
air concentration is inversely related to
the wind speed at the point of release.
Concentrations are also affected by the
turbulence of the air, which tends to
increase with wind speed and sunlight,
and by meandering of the plume, which
is greater at the lower wind speeds.
This results in higher concentrations
generally being associated with low
winds near the source, and with
moderate winds at larger distances.
Higher windspeed also shortens the
travel time. Planning information on
time frames for releases from nuclear
power facilities may be found in
Reference NR-78. Time frames for
releases from other facilities will
depend on the characteristics of the
facility.
5-7
-------
Since a change in wind direction
will also affect the duration of
exposure, it is very important that
arrangements be made for a public,
private, or military professional
weather service to provide information
on current meteorological and wind
conditions and predicted wind direction
persistence during an incident, in
addition to information received from
the facility operator.
5.4.2 Dose Conversion Factors
This section provides dose
conversion factors (DCFs) and derived
response levels (DRLs) for those
radionuclides important for responding
to most types of incidents. These are
supplemented by an example to
demonstrate their application. The
DCFs are useful where multiple
radionuclides are involved, because the
total dose from a single exposure
pathway will be the sum of the doses
calculated for each radionuclide. The
DELs are surrogates for the PAG and
are directly usable for releases
consisting primarily of a single nuclide,
in which case the DHL can be
compared directly to the measured or
calculated concentration. (DRLs also
can be used for multiple radionuclides
by summing the ratios of the
environmental concentration of each
nucHde to its respective DRL. To meet
the PAG, this sum must be equal to or
less than unity.)
DCFs and DRLs for each of the
three major exposure pathways for the
early phase (external exposure to
plume, plume inhalation, and external
exposure from deposited materials) are
provided separately in Section 5.6.
They are all expressed in terms of the
time-integrated air concentration at the
receptor so they can be conveniently
summed over the three exposure
pathways to obtain composite DRLs
and DCFs for each radionuclide. These
composite values are tabulated in Table
5-1 for effective dose and in Table 5-2
for thyroid dose from inhalation of
radioiodmes.
The tabulated DCFs and DRLs
include assumptions on particle size,
deposition velocity, the presence of
short-lived daughters, and exposure
duration as noted. The existence of
more accurate data for individual
radionuclides may justify modification
of the DCFs and DRLs. The
procedures described in Section 5.6 for
developing the DCFs and DRLs for
individual exposure pathways may be
referred to, to assist such
modifications.
To apply Tables 5-1 and 5-2 to
decisions on implementing PAGs, one
may use either the DCFs or DRLs.
DCFs are used to calculate the
projected composite dose for each
radionuclide; these doses are then
summed and compared to the PAG.
The DRLs may be used by summing
the ratios of the concentration of each
radionuclide to its corresponding DRL.
If the sum of the ratios exceeds unity,
the corresponding protective action
should be initiated.
5-8
-------
Table 5-1 Dose Conversion Factors (DCF) and Derived Response Levels (DHL) for
Combined*1 Exposure Pathways During the Early Phase of a Nuclear
Incident13
Radionuclide
H-3
C-14
Na-22
Na-24
P-32
P-33
S-35
Cl-36
K-40
K-42
Ca-45
Sc-46
Ti-44
V-48
Cr-51
Mn-54
Mn-56
Fe-55
Fe-59
Co-58
Co-60
Ni-63
Cu-64
Zn-65
Ge-68
Se-75
Kr-85
Kr-85m
Kr-87
Kr-88
DCF
rem per
uCi • cm"3 • h
7.7E+01
2.5E+03
1.9E+04
7.3E+03
1.9E+04
2.8E+03
3.0E+03
2.6E+04
1.6E+04
2.0E+03
8.0E+03
4.4E+04
1.2E+06
2.4E+04
5.5E+02
1.2E+04
1.8E+03
3.2E+03
2.3E+04
1.7E+04
2.7E+05
7.6E+03
5.9E+02
2.7E+04
6.2E+04
1.2E+04
1.3E+00
9.3E+01
5.1E+02
1.3E+03
DRLC
uCi • cm'3 • h
1.3E-02
4.0E-04
5.3E-05
1.4E-04
5.4E-05
3.6E-04
3.4E-04
3.8E-05
6.5E-05
5.1E-04
1.3E-04
2.3E-05
8.2E-07
4.2E-05
1.8E-03
8.5E-05
5.7E-04
3.1E-04
4.4E-05
5.7E-05
3.7E-06
1.3E-04
1.7E-03
3.7E-05
1.6E-05
8.3E-05
7.8E-01
1.1E-02
2.0E-03
7.8E-04
5-9
-------
Table 5-1, Continued
Radionuclide
DCF
rem per
uCi • cm"3 • h
DRLC
uCi -cm"3 -h
Kr-89
Rb-86
Rb-88
Rb-89
Sr-89
Sr-90
Sr-91
Y-90
Y-91
Zr-93
Zr-95
Zr-97
Nb-94
Nb-95
Mo-99
Tc-99
Tc-99m
Ru-103
Ru-105
Ru/Rh-106d
Pd-109
Ag-llOm
Cd-109
Cd-113m
In-114m
Sn-113
Sn-123
Sn-125
Sn-126
Sb-124
1.2E+03
8.3E+03
5.2E+02
1.4E+03
5.0E+04
1.6E+06
2.4E+03
l.OE+04
5.9E+04
3.9E+05
3.2E+04
5.5E+03
5.0E+05
l.OE+04
5.2E+03
l.OE+04
1.7E+02
1.3E+04
1.2E+03
5.7E+05
1.3E+03
9.8E+04
1.4E+05
1.8E+06
1.1E+05
1.3E+04
3.9E+04
2.0E+04
1.2E+05
3.8E+04
8.6E-04
1.2E-04
1.9E-03
7.3E-04
2.0E-05
6.4E-07
4.2E-04
9.9E-05
1.7E-05
2.6E-06
3.2E-05
1.8E-04
2.0E-06
9.7E-05
1.9E-04
l.OE-04
6.0E-03
7.7E-05
8.2E-04
1.7E-06
7.6E-04
l.OE-05
7.3E-06
5.5E-07
9.4E-06
7.8E-05
2.6E-05
5.1E-05
8.4E-06
2.6E-05
5-10
-------
Table 5-1, Continued
Radionuclide
DCF
rem per
uCi • cm3 • h
DRLC
uCi • cm"3 • h
Sb-126
Sb-127
Sb-129
Te-127m
Te-129
Te-129m
Te-131m
Te-132
Te/I-132d
Te-134
1-125
1-129
1-131
I-1326
1-133
1-134
1-135
Xe-131m
Xe-133
Xe-133m
Xe-135
Xe-135m
Xe-137
Xe-138
Cs-134
Cs-136
Cs/Ba-137d
Cs-138
Ba-133
Ba-139
2.6E+04
9.5E+03
2.0E+03
2.6E+04
1.4E+02
2.9E+04
8.6E+03
1.2E+04
2.0E+04
7.0E+02
3.0E+04
2.1E+05
5.3E+04
4.9E+03
1.5E+04
3.1E+03
8.1E+03
4.9E+00
2.0E+01
1.7E+01
1.4E+02
2.5E+02
1.1E+02
7.2E+02
6.3E+04
1.8E+04
4.1E+04
1.6E+03
1.1E+04
2.3E+02
3.9E-05
1.1E-04
5.0E-04
3.9E-05
7.0E-03
3.5E-05
1.2E-04
8.5E-05
5.0E-05
1.4E-03
3.3E-05
4.8E-06
1.9E-05
2.0E-04
6.8E-05
3.3E-04
1.2E-04
2.0E-01
5.0E-02
5.9E-02
7.0E-03
4.1E-03
9.3E-03
1.4E-03
1.6E-05
5.6E-05
2.4E-05
6.1E-04
8.9E-05
4.4E-03
5-11
-------
Table 5-1, Continued
Radionuclide
DCF
rem per
uCi • cm"3 • h
DRLC
p.Ci -cm'3 -h
Ba-140
La-140
La-141
La-142
Ce-141
Ce-143
Ce-144
Ce/Pr-144d
Nd-147
Pm-145
Pm-147
Pm-149
Pm-151
Sm-151
Eu-152
Eu-154
Eu-155
Gd-153
Tb-160
Ho-166m
Tm-170
Yb-169
Hf-181
Ta-182
W-187
Ir-192
Au-198
Hg-203
Tl-204
Pb-210
5.3E+03
1.1E+04
7.3E+02
2.3E+03
1.1E+04
4.7E+03
4.5E+05
4.5E+05
8.8E+03
3.7E+04
4.7E+04
3.6E+03
2.8E+03
3.6E+04
2.7E+05
3.5E+05
5.0E+04
2.9E+04
3.5E+04
9.4E+05
3.2E+04
1.1E+04
2.1E+04
6.0E+04
1.7E+03
3.8E+04
5.2E+03
9.9E+03
2.9E+03
1.6E+07
1.9E-04
8.8E-05
1.4E-03
4.3E-04
9.0E-05
2.1E-04
2.2E-06
2.2E+06
1.1E-04
2.7E-05
2.1E-05
2.8E-04
3.5E-04
2.8E-05
3.8E-06
2.9E-06
2.0E-05
3.4E-05
2.9E-05
1.1E-06
3.2E-05
8.9E-05
4.8E-05
1.7E-05
6.0E-04
2.7E-05
1.9E-04
l.OE-04
3.5E-04
6.1E-08
5-12
-------
Table 5-1, Continued
Radionuclide
Bi-207
Bi-210
Po-210
Ra-226
Ac-227
Ac-228
Th-227
Th-228
Th-230
Th-232
i
Pa-231 7
U-232
U-233
U-234
U-235
U-236
U-238
U-240
Np-237
Np-239
Pu-236
Pu-238
Pu-239
Pu-240
Pu-241
Pu-242
Am-241
Am-242m
Am-243
Cm-242
DCF
rem per
uCi • cm'3 • h
3.1E+04
1.9E+04
1.1E+07
l.OE+07
8.0E+09
3.7E+05
1.9E+07
4.1E+08
3.9E+08
2.0E+09
1.5E+09
7.9E+08
1.6E+08
1.6E+08
1.5E+08
1.5E+08
1.4E+08
2.7E+03
6.5E+08
3.6E+03
1.7E+08
4.7E+08
5.2E+08
5.2E+08
9.9E+06
4.9E+08
5.3E-5-08
5.1E+08
5.3E+08
2.1E+07
DRLC
]iCi ' cm"3 • h
3.2E-05
5.3E-05
: 8.9E-08
9.7E-08
1.2E-10
2.7E-06
5.2E-08
2.4E-09
2.6E-09
5.1E-10
6.5E-10
1.3E-09
6.2E-09
6.3E-09
6.8E-09
6.6E-09
7.0E-09
3.7E-04
; 1.5E-09
; 2.8E-04
! 5.8E-09
2.1E-09
i 1.9E-09
1.9E-09
!• l.OE-07
2.0E-09
1.9E-09
• 2.0E-09
I 1.9E-09
4.8E-08
5-13
-------
Table 5-1, Continued
Radionuclide
DCF
rem per
uCi • cm3 • h
DRLC
uCi • cm3 • h
Cm-243
Cm-244
Cm-245
Cm-246
Cf-252
3.7E+08
3.0E+08
5.5E+08
5.4E+08
1.9E+08
2.7E-09
3.4E-09
1.8E-09
1.9E-09
5.3E-09
"Sum of doses from external exposure and inhalation from the plume, and external exposure from
deposition. "Dose" means the sum of effective dose equivalent from external radiation and committed
effective dose equivalent from intake.
bSee footnote a to Table 5-4 for assumptions on inhalation and footnote b to Table 5-5 for assumptions
on deposition velocity. The quantity uCi- cm"3- h refers to the time-integrated air concentration at one
meter height.
Tor 1 rem committed effective dose equivalent.
dThe contribution from the short-lived daughter is included in the factors for the parent radionuclide.
'These factors should only be used in situations where 1-132 appears without the parent radionuclide.
Persons exposed to an airborne
particulate plume will receive dose to
skin from beta emitters in the plume
as well as from those deposited on skin
and clothing. Although it is possible to
detect beta radiation, it is not practical,
for purposes of decisions on evacuation
and sheltering, to determine dose to
skin by field measurement of the beta
dose equivalent rate near the skin
surface. Such doses are determined
more practically through calculations
based on time-integrated air
concentration, an assumed deposition
velocity, and an assumed time period
between deposition and skin
decontamination. For the purpose of
evaluating the relative importance of
skin dose compared to the dose from
external gamma exposure and
inhalation, dose conversion factors
were evaluated using a deposition
velocity of 1 cm/sec and an exposure
time before decontamination of 12
hours. Using these conservative
assumptions, it was determined that
skin beta dose should seldom, if ever,
be a controlling pathway during the
early phase. Therefore, no DCFs or
DRLs are listed for skin beta dose.
5-14
-------
Table 5-2 Dose Conversion Factors (DCF) and Derived Response Levels (DRL)
Corresponding to a 5 rem Dose Equivalent to the Thyroid from Inhalation
of Radioiodine
Radionuclide
Te/I-132b
1-125
1-129
1-131
1-132
1-133
1-134
1-135
DCF
rem per
uCi • cm'3 • h
2.9E+05
9.6E+05
6.9E+06
1.3E+06
7.7E+03
2.2E+05
1.3E+03
3.8E+04
DRLa
uCi • cm"3 • h
1.8E-05
5.2E-06
7.2E-07
3.9E-06
6.5E-04
2.3E-05
3.9E-03
1.3E-04
Tor a 5 rem committed dose equivalent to the thyroid.
'The contribution from the short-lived daughter is included in the factors for the parent radionuclide.
Because of large uncertainties in
the assumptions for deposition, air
concentrations are an inadequate basis
for decisions on the need to
decontaminate individuals. Field
measurements should be used for this
(See Chapter 7, Section 7.6.3.). It
should be noted that, even in situations
where the skin beta dose might exceed
50 rem, evacuation would not usually
be the appropriate protective action,
because skin decontamination and
clothing changes are easily available
and effective. However, evacuation
would usually already be justified in
these situations due to dose from
inhalation during plume passage.
The following example demonstrates
the use of the data in Tables 5-1 and 5-
2 for a simple analysis involving three
radionuclides.
Based on source term and
meteorological considerations, it is
assumed that the worst probable
nuclear incident at an industrial
facility is a fire that could disperse
radioactive material into the.
atmosphere, yielding a time-integrated
concentration of radionuclides at a
nearby populated area, as follows:
Radionuclide
Zr-95
Cs-134
1-131
uCi- cm-h
2E-6
4E-8
1.2E-5
5-15
-------
We examine whether evacuation is
warranted at these levels, based on
PAGs of 1 rem for effective dose and 5
rem for dose to the thyroid. We use
the DCPs in Table 5-1 for effective dose
and Table 5-2 for thyroid dose from
inhalation of radioiodines to calculate
the relevant doses, H, as follows:
where DCFi
and
- dose conversion
factor for
radionuclide i,
Cf = time-integrated
concentration of
radionuclide i,
n = the number of
radionuclides
present.
For the committed effective dose
equivalent (see Table 5-1):
(2 1-6 x 3.2E+4)+(4E-8 x 6.3 E+4)
•f(1.2E-5 x 5.3E+4) = 0.71 rem.
For the committed dose equiva-
lent to the thyroid (see Table 5-2):
1.2E-5 x 1.3E+6 = 16 rem.
The results of these calculations
show that, at the location for which
these time-integrated concentrations
are specified, the committed dose
equivalent to the thyroid from
inhalation would be over three times
the PAG for dose to thyroid, thus
justifying evacuation. Using
meteorological dilution factors, one
could calculate the additional distance
to which evacuation would be justified
to avoid exceeding the PAG for thyroid
dose.
To use the DRLs from Table 5-1
and 5-2, find the sum,
n f~t
'
for both effective dose and thyroid dose,
where DRL} is the derived response
level for radionuclide i, and Cj is
defined above. If the sum in either
case is equal to or greater than unity,
evacuation of the general population is
warranted.
For effective dose (see
Table 5-1):
ZE-6
4E-8
1.2E-5
3.2E-5 1.6E-5 I.9E-5
For dose to the thyroid (see
Table 5-2):
= 0.7
1.2E-5
3.9^-6
= 3
It is apparent that these calculations
yield the same conclusions as those
using the DCFs.
5.4.3 Comparison with Previously-
Recommended PAGs
Many emergency response plans
have already been developed using
previously-recommended PAGs that
apply to the dose equivalent to the
whole body from direct (gamma)
radiation from the plume and to the
thyroid from inhalation of radioiodines.
For nuclear power plant incidents, the
5-16
-------
former PAG for whole body exposure
provides public health protection
comparable to that provided by the new
PAG expressed in terms of effective
dose equivalent. This is demonstrated
in Table C-9 (Appendix C), which
shows comparative doses for nuclear
power plant fuel-melt accident
sequences having a wide range of
magnitudes. The PAG for the thyroid
is unchanged. On the other hand,
application of these PAGs to alpha
emitting radionuclides leads to quite
different derived response levels from
those based on earlier health physics
considerations, because of new dose
conversion factors and the weighting
factors assigned to the exposed organs
(EP-88).
5.5 Protective Actions
This section provides guidance for
implementing the principal protective
actions (evacuation and sheltering) for
protection against the various exposure
pathways resulting from an airborne
plume. Sheltering means the use of
the closest available structure which
will provide protection from exposure
to an airborne plume, and evacuation
means the movement of individuals
away from the path of the plume.
Evacuation and sheltering
provide different levels of dose
reduction for the principal exposure
pathways (inhalation of radioactive
material, and direct gamma exposure
from the plume or from material
deposited on surfaces). The
effectiveness of evacuation will depend
on many factors, such as how rapidly it
can be implemented and the nature of
the accident. For accidents where the
principal source of dose is inhalation,
evacuation could increase exposure if it
is implemented during the passage of a
short-term plume, since moving
vehicles provide little protection
against exposure (DO-90). However,
studies (NR-89a) continue to show that,
for virtually all severe reactor accident
scenarios, evacuation during plume
passage does not increase the risk of
acute health effects above the risk
while sheltering. Sheltering, which in
most cases can.be almost immediately
implemented, varies in usefulness
depending upon the type of release, the
shelter available, the duration of the
plume passage, and climatic conditions.
Studies have been conducted to
evaluate shelter (EP-78a) and
evacuation (HA-75) as protective
actions for incidents at nuclear power
facilities. Reference EP-78b suggests
one method for evaluating and
comparing the benefits of these two
actions. This requires collecting
planning information before and data
following an incident, and using
calculations and graphical means to
evaluate whether evacuation,
sheltering, or a combination of
sheltering followed by evacuation
should be recommended at different
locations. Because of the many
interacting variables, the user is forced
to choose between making decisions
during the planning phase, based on
assumed data that may be grossly
inaccurate, or using a time-consuming
more comprehensive process after the
5-17
-------
incident when data may be available.
In the former situation, the decision
may not have a sound basis, whereas
in the latter, the decision may come too
late to be useful.
The recommended approach is to
use planning information for making
early decisions. The planned response
should then be modified following the
incident only if timely detailed
information is available to support such
modifications.
The planner should first compile
the necessary information about the
emergency planning zone (EPZ) around
the facility. For the case of power
reactors, some of this information is
described in NUREG-0654 (NR-80). It
should include identifying the
population distribution, the sheltering
effectiveness of residences and other
structures, institutions containing
population groups that require special
consideration, evacuation routes, logical
boundaries for evacuation zones,
transportation systems,
communications systems, and special
problem areas. In addition, the
planner should identify the information
that may be available following an
incident, such as environmental
monitoring data, meteorological
conditions, and plant conditions. The
planner should identify key data or
information that would justify specific
protective actions. The evaluation and
planning should also include the
selection of institutions where persons
should be provided with stable iodine
for thyroid protection in situations
where radioiodine inhalation is
projected.
The following sections discuss key
factors which affect the choice between
evacuation and sheltering.
5.5.1 Evacuation
The primary objective of evacuation
is to avoid exposure to airborne or
deposited radioactive material by
moving individuals away from the path
of the plume. Evacuation, if completed
before plume arrival, can be 100
percent effective in avoiding future
exposure. Even if evacuation coincides
with or follows plume passage, a large
reduction of exposure may be possible.
In any case, the maximum dose
avoided by evacuation will be the dose
not avoidable by sheltering.
Some general conclusions
regarding evacuation (HA-75) which
may be useful for planning purposes
are summarized below:
1. Advanced planning is essential to
identify potential problems that may
occur in an evacuation.
2. Most evacuees use their own
personal transportation.
3. Most evacuees assume the
responsibility of acquiring food and
shelter for themselves.
4. Evacuation costs are highly
location-dependent and usually will not
5-18
-------
be a deterrent to carrying out an
evacuation.
5. Neither panic nor hysteria has
been observed when evacuation of large
areas is managed by public officials,
6. Large or small population groups
can be evacuated effectively with
minimal risk of injury or death.
7. The risk of injury or death to
individual evacuees from transporta-
tion does not change as a function of
the number of persons evacuated, and
can be conservatively estimated using
National Highway Safety Council
statistics for motor vehicle accidents
(subjective information suggests that
the risks will be lower).
Evacuation of the elderly, the
handicapped, and inhabitants of
medical and other institutions may
present special problems. When
sheltering can provide adequate
protection, this will often be the
protective action of choice. However, if
the general public is evacuated and
those in institutions are sheltered,
there is a risk that attendants at these
institutions may leave and make later
evacuation of institutionalized persons
difficult because of a lack of
attendants. Conversely, if evacuation
of institutions is attempted during
evacuation of the public, traffic
conditions may cause unacceptable
delays. If evacuation of institutions is
attempted before evacuating the public,
increased risk to the public from a
delayed evacuation could occur, unless
the incident is very slow in developing
to the point of an atmospheric release.
Because of the above difficulties,
medical and other institutions located
within the EPZ should be evaluated to
determine whether there are any
logical categories of persons that
should be evacuated after the public
(or, when time permits, before).
5.5.2 Sheltering
Sheltering refers here to the use of
readily available nearby structures for
protection against exposure to an
airborne plume.
Sheltering may be an appropriate
protective action because;
1. It positions the public to receive
additional instructions when the
possibility of high enough doses to
justify evacuation exists, but is small.
2. It may provide protection equal to
or greater than evacuation.
3. It is less expensive and disruptive
than evacuation.
4. Since it may be implemented
rapidly, sheltering may be the
protective action of choice if rapid
evacuation is impeded by, a) severe
environmental conditions—e.g. severe
weather or floods; b) health
constraints~e.g. patients and workers
in hospitals and nursing homes; or c)
long mobilization times—certain
industrial and farm workers, or
prisoners and guards; d) physical
5-19
-------
constraints to evacuation—e.g.
inadequate roads.
5. Sheltering may be more effective
against inhalation of radioactive
particulates than against external
gamma exposure, especially for short-
term plumes.
The use of large structures, such as
shopping centers, schools, churches,
and commercial buildings, as collection
points during evacuation mobilization
will generally provide greater
protection against gamma radiation
than use of small structures.
As with evacuation, delay in taking
shelter during plume passage will
reduce the protection from exposure to
radiation. The degree of protection
provided by structures is,governed by
attenuation of gamma radiation by
structural components (the mass of
walls, ceilings, etc.) and by
outside/inside air-exchange rates.
If external dose from the plume or
from deposited materials is the
controlling criterion, shelter
construction and shelter size are the
most important considerations;
ventilation control and filtering are less
important. Although sheltering will
reduce the gamma exposure rate from
deposited materials, it is not a suitable
protective action for this pathway for
long duration exposure. The main
factors which reduce whole body
exposure are:
1. Wall materials and thickness and
size of structure,
2. Number of stories overhead, and
3. Use of a central location within
the structure.
If a major release of radioiodine or
respirable particulate materials occurs,
inhalation dose will be the controlling
pathway. For releases consisting
primarily of noble gases, external
gamma exposure will be most
important. However, when inhalation
is the primary exposure pathway,
consideration should be given to the
following:
1. Ventilation control is essential for
effective sheltering.
2. Dose reduction factors for
sheltering can be improved in several
ways for the inhalation pathway,
including reducing air exchange rates
by sealing cracks and openings with
cloth or weather stripping, tape, etc.
Although the risk to health from the
action could be a constraint
(particularly for infants and the
infirm), using wet towels or
handkerchiefs as a mask to filter the
inhaled air will reduce dose from
inhalation.
3. Following plume passage, people
should open shelters to reduce airborne
activity trapped inside, and they should
leave high exposure areas as soon as
possible after cloud passage to avoid
exposure to deposited radioactive
material.
4. Consideration should be given to
the prophylactic administration of
potassium iodide (KI) as a
5-20
-------
thyroid-blocking agent to workers
performing emergency services and
other groups in accordance with the
PAGs in Table 2-1 and the provisions
in reference FD-82.3
5.5.3 General Guidance for Evacuation
and Sheltering
The process of evaluating,
recommending, and implementing
evacuation or shelter for the public is
far from an exact science, particularly
in view of time constraints that prevent
thorough analysis at the time of an
incident. Their effectiveness, however,
can be improved considerably by
planning and testing. Early decisions
should be based on information
collected from the emergency planning
zone during the planning phase and on
information regarding conditions at the
nuclear facility at the time of the
incident. Best estimates of dose
projections should be used for decisions
between evacuation and sheltering.
The following is a summary of
planning guidance for evacuation and
sheltering, based on the information in
Sections 5.5.1 and 5.5.2.
1. For severe incidents, where PAGs
may be significantly exceeded,
3Each State has the responsibility for
formulating guidance to define when (and if)
the public should be given potassium iodide.
Planning for its use is discussed in "Potassium
Iodide as a Thyroid-blocking Agent in a
Radiation Emergency: Final Recommendations
on Use" (FD-82).
evacuation may be the only effective
protective action close to the facility.
2. Evacuation will provide total
protection from any airborne release if
it is completed before arrival of the
plume.
3. Evacuation may increase exposure
if carried out during the plume
passage, for accidents involving
inhalation dose as a major contributor.
4. Evacuation is also appropriate for
protection from groundshine in areas
with high exposure rates from
deposited materials.
t
5. Sheltering may be appropriate
(when available) for areas not
designated for immediate evacuation
because:
a. It positions the public to receive
additional instructions; and
b. It may provide protection equal to
or greater than evacuation.
6. Sheltering is usually not
appropriate where high doses are
projected or for exposure lasting longer
than two complete air exchanges of the
shelter.
7. Because sheltering may be
implemented in less time than
evacuation, it may be the temporary
protective action of choice if rapid
evacuation is impeded by a) certain
environmental conditions--e.g. severe
weather or floods; b) health
constraints~e.g. patients and workers
5-21
-------
in hospitals and nursing homes; or c)
long mobilization times~e.g. certain
industrial and farm workers, or
prisoners and guards; d) physical
constraints to evacuation—e.g.
inadequate roads.
8. If a major release of radioiodine or
particulate materials occurs, inhalation
dose may be the controlling criterion
for protective actions. In this case:
a. Breathing air filtered through
common household items (e.g.,
folded wet handkerchiefs or towels)
may be of significant help, if
appropriate precautions are taken
to avoid possible suffocation.
b. After confirmation that the
plume has passed, shelters should
be opened to avoid airborne activity
trapped inside, and persons should
leave high exposure areas as soon
as possible after cloud passage to
avoid exposure to deposited
radioactive material.
c. Consideration should be given to
the prophylactic administration of
potassium iodide (KI) as a
thyroid-blocking agent to emergency
workers, workers in critical
industries, or others in accordance
with the PAGs in Table 2-1 and
reference FD-82.
9. If dose from external gamma
radiation is the controlling criterion,
shelter construction and size are the
most important considerations;
ventilation control and filtering are less
important. The main factors which
reduce whole body external dose are; a)
wall thickness and size of structure, b)
number of stories overhead, c) central
location within the structure, and d)
the height of the cloud with respect to
the building.
5.6 Procedures for Calculating Dose
Conversion Factors
This section provides information
used in the development of the DCFs in
Tables 5-1 and 5-2. Three exposure
pathways are included: whole body
exposure to gamma radiation from the
plume, inhalation from the plume, and
whole body exposure to gamma
radiation from deposited materials.
Although exposure of the skin from
beta radiation could be significant,
evaluations show that other exposure
pathways will be controlling for
evacuation and sheltering decisions.
Therefore, DCFs for skin are not
provided. Individual DCFs for the
three exposure pathways are provided
in the following sections. They are
each expressed in terms of the time-
integrated air concentration so that
they may be combined to yield a
composite DCF for each radionuclide
that reflects all three pathways. These
data may be used to facilitate revising
the DCFs in Tables 5-1 and 5-2 when
more specific or technically improved
assumptions are available, as well as to
evaluate the relative importance of the
individual pathways for specific
radionuclide mixes.
5-22
-------
5.6.1 External Exposure to Gamma
Radiation from the Plume
Table 5-3 provides DCFs and DRLs
for external exposure to gamma
radiation due to immersion in
contaminated air. The values for
gamma radiation will provide
conservative estimates for exposure to
an overhead plume. They are derived
under the assumption that the plume
is correctly approximated by a semi-
infinite source.
The DCFs given in Table 5-3 are used
to calculate the effective dose
equivalent from external exposure to
gamma radiation from the plume.
They are based on dose-rate conversion
factors for effective dose in Table A.I of
reference DO-88. The units given in
Table A.1 are converted to those in
Table 5-3 as follows:
mrem
,-i
uCi • m
~3
x 0.1142 =
rent
pCi -cm'3 - h
Only the short-lived daughters of Ru-
106 and Cs-137 emit gamma radiation
and, therefore, the DCFs from Table
A.I for these entries are attributable to
their daughters. The DCF for Ce-144
is combined with that for its short-lived
daughter; it is assumed they are in
equilibrium. Since the DRLs apply to
a PAG of 1 rem, they are simply the
reciprocals of the DCFs.
5.6.2 Inhalation from the Plume
Table 5-4 provides DCFs and DRLs
for committed effective dose equivalent
due to inhalation of an airborne plume
of radioactive participate materials and
for committed dose equivalent to the
thyroid due to inhalation of
radioiodines. It is assumed that the
radionuclides are in the chemical and
physical form that yields the highest
dose, and that the particle size is one
micrometer mean aerodynamic
diameter. For other chemical and
physical forms of practical interest the
doses may differ, but in general only by
a small factor. If the chemical and/or
physical form (e.g. solubility class or
particle size) is known or can be
predicted, the DCFs for inhalation
should be adjusted as appropriate.
The dose factors and breathing rate
used to develop the DCFs in Table 5-4
are those given in Table 2.1 of Federal
Guidance Report No. 11 and were
derived for "standard man" (EP-88).
Although the DCFs for some
radionuclides would be slightly higher
for children, the conservatism in the
PAGs and procedures for their
application provide an adequate margin
for safety. The advantage of using a
single source of current data for the
development and timely revision of
DCFs for these and any other relevant
radionuclides is also a consideration in
the selection of this data base for use
in emergency response applications.
The units given in Table 2-1 of EP-88
are converted to the units in Table 5-4,
using a breathing rate of 1.2E+6 cm3 •
h"1, by the factor
Sv-Bq'1 • 4.4E+12 =.rem per
uCi- cm"3-h.
5-23
-------
The DRLs are simply the reciprocal of
the DCF.
5.6.3 External Dose from. Deposited
Materials
Table 5-5 provides DCFs and DRLs
for 4-day exposure to gamma radiation
from selected radionuelides following
deposition of partieulate materials on
the ground from a plume. The
deposition velocity (assumed to be 1
cm/s for iodines and 0.1 cm/s for other
particulate materials) could vary
widely depending on the physical and
chemical characteristics of the
deposited material and the surface, and
meteorological conditions. In the case
of precipitation, the amount of
deposition (and thus the dose
conversion factors for this exposure
pathway) will be much higher. To
account for the ingrowth of short-lived
daughters in deposited materials after
measurements are made, the tabulated
values include their contribution to
dose over the assumed 4-day period of
exposure. Because the deposition
velocity can be much lower or higher
than assumed in developing the dose
conversion factors for deposited
materials, decision makers are
cautioned to pay particular attention to
actual measurements of gamma
exposure from deposited materials for
evacuation decisions after plume
passage.
The objective is to calculate DCFs for
single radionuclides in terms of
effective dose equivalent from 4 days
exposure to gamma radiation from
deposited radioactive materials. In
order to be able to sum tib.e dose
conversion factors with those for other
exposure pathways, the DCP is
expressed in terms of dose per unit
time-integrated air concentration,
where the deposition from the plume is
assumed to occur at approximately the
beginning of the incident. The
following equation was used to
generate Table 5-5:
DCF = V- DCRF
8
h)
h"1
h"1
Where:
DCF = the dose per unit air
concentration (uCi- cm"3
Vg = the deposition velocity,
assumed to be 3600 cm-
for iodines and 360 cm-
for other particulate
materials
DRCF = the dose rate conversion
factor (mrem- y" 1 per
uCi- m'2) (DO-88)
1.14E-3 = a factor converting
mrem
rem
X = the decay constant for the
radionuclide (h"1)
t = duration of exposure
(hours),assumed to be 96
hours (4 days)
y"1 per m2 to
h"1 per cm2
5-24
-------
Table 5-3 Dose Conversion Factors (DCF) and Derived Response Levels (DRL) for
External Exposure Due to Immersion in Contaminated Air
Radionuclide
H-3
C-14
Na-22
Na-24
P-32
P-33
S-35
Cl-36
K-40
K-42
Ca-45
Sc-46
Ti-44
V-48
Cr-51
Mn-54
Mn-56
Fe-55
Fe-59
Co-58
Co-60
Ni-63
Cu-64
Zn-65
Ge-68
Se-75
Kr-85
Kr-85m
Kr-87
Kr-88
DCFa
rem per
uCi • cm"3 • h
O.OE+00
O.OE+00
1.3E+03
2.7E+03
O.OE+00
O.OE+00
O.OE+00
4.8E-06
9.2E+01
1.7E+02
9.3E-09
1.2E+03
7.7E+01
1.7E+03
1.8E+01
5.0E+02
1.1E+03
1.3E-02
7.0E+02
5.8E+02
1.5E+03
O.OE+00
1.1E+02
3.4E+02
5.2E-02
2.3E+02
1.3E+00
9.3E+01
5.1E+02
1.3E+03
DRLb
uCi-cm-3-h
O.OE+00
O.OE+00
7.8E-04
3.7E-04
O.OE+00
O.OE+00
O.OE+00
2.1E+05
1.1E-02
6.0E-03
1.1E+08
8.4E-04
1.3E-02
5.8E-04
5.6E-02
2.0E-03
9.4E-04
7.6E+01
1.4E-03
1.7E-03
6.7E-04
O.OE+00
9.2E-03
2.9E-03
1.9E+01
4.4E-03
7.8E-01
1.1E-02
2.0E-03
7.8E-04
5-25
-------
Table 5-3, Continued
Radionuelide
Kr-89
Eb-86
Rb-88
Rb-89
Sr-89
Sr-90
Sr-91
Y-90
Y-91
Zr-93
Zr-95
Zr-97
Nb-94
Nb-95
Mo-99
Te-99
Tc-99m
Ru-103
Ru-105
Ru/Rh.-106°
Pd-109
Ag-llOm
Cd-109
Cd-113m
In-114m
Sn-113
Sn-123
Sn-125
Sn-126
Sb-124
DCF*
remper
jiCi • cm'3 • h
1.2E+03
5.6E+01
4.1E+02
1.3E+03
8.2E-02
O.OE+00
4.1E+02
O.OE+00
2.1E+00
O.OE+00
4.3E+02
1.1E+02
9.3E+02
4.5E+02
9.1E+01
3.0E-04
7.6E+01
2.8E+02
4.6E+02
1.2E+02
3.9E-01
1.6E+03
1.3E+00
O.OE+00
5.2E+01
4.8E+00
4.1E+00
1.8E+02
2.8E+01
1.1E+03
DRLb
pCi • cm8 • h
8.6E-04
1.8E-02
2.5E-03
7.7E-04
1.2E+01
O.OE+00
2.4E-03
O.OE+00
4.7E-01
O.OE+00
2.3E-03
9.3E-03
1.1E-03
2.2E-03
1.1E-02
3.3E+03
1JE-02
3.6E-03
2.2E-03
8.4E-03
2.5E+00
6.2E-04
8.0E-01 ,
O.OE+00
1.9E-02
2.1E-01
2.4E-01
5.4E-03
3.6E-02
8.8E-04
5-26
-------
Table 5-3, Continued
RadionucMde
Sb-126
Sb-127
Sb-129
Te-127m
Te-129
Te-129m
Te-131m
Te-132
Te-134
1-125
1-129
1-131
1-132
1-133
1-134
1-135
Xe-131m
Xe-133
Xe-133m
Xe-135
Xe-135m
Xe-137
Xe-138
Cs-134
Cs-136
Cs/Ba-137c
Cs-138
Ba-133
Ba-139
Ba-140
DCF*
remper
jiCi • can'3 * h.
1.6E+03
3.9E+02
8.6E+02
1.8E+00
3.1E+Q1
2.0E+01
8.5E+02
1.2E+02
5.1E+02
6.3E+00
4.8E+00
2.2E+02
1.4E+03
3.5E+02
1.6E+03
9.5E+02
4.9E+00
2.0E+01
1.7E+01
1.4E+02
2.5E+02
1.1E+02
7.1E+02
9.1E+02
1.3E+03
3.5E+02
1.4E+03
2.1E+02
2.1E+01
1.1E+02
DRLb
|iCi • cm'3 • h
6.2E-04
2.6E-03
1.2E-03
5.6E-01
3.2E-02
5.1E-02
1.2E-03
8.0E-03
2.0E-03
1.6E-01
2.1E-01
4.6E-03
7.4E-04
2.9E-03
6.4E-04
1.1E-03
2.0E-01
5.0E-02
5.9E-02
7.0E-03
4.1E-03
9.2E-03
1.4E-03
1.1E-03
7.8E-04
2.9E-03
6.9E-04
4.8E-03
4.9E-02
9JE-03
5-27
-------
Table 5-3, Continued
Radionuclide
La-140
La-141
La-142
Ce-141
Ce-143
Ce-144
Ce/Pr-144°
Nd-147
Pm-145
Pm-147
Pm-149
Pm-151
Sm-151
Eu-152
Eu-154
Eu-155
Gd-153
Tb-160
Ho-166m
Tm-170
Yb-169
Hf-181
Ta-182
W-187
Ir-192
Aw-198
Hg-203
Tl-204
Pb-210
Bi-207
DCFa
rem per
p.Ci • cm"3 • h.
1.4E+03
2.5E+01
1.8E+03
4.4E+01
1.5E+02
l.OE+01
3.1E+01
7.6E+01
9.5E+00
2, IE-OS
; 6.7E+00
1.9E+02
5.2E-04
6.7E+02
7.4E+02
3.3E+01
5.1E+01
6.4E+02
9.4E+02
2.7E+00
1.6E+02
3.1E+02
7.6E+02
2.7E+02
4.7E+02
2.3E+02
1.3E+02
5.8E-01
7.6E-01
9.1E+02
DRLb
jiCi • cm"3 • h
7.1E-04
3.9E-02
5.6E-04
2.3E-02
6.6E-03
9.7E-02
3.2E-02
L3E-02
l.OE-01
4.8E+02
1.5E-01
5.2E-03
1.9E+03
1.5E-03
1.3E-03
3.1E-02
2.0E-02
1.6E-03
1.1E-03
3.8E-01
6.1E-03
3.2E-03
1.3E-03
3.6E-03
2.1E-03
4JE-03
7.6E-03
1.7E+00
1.3E+00
1.1E-03
5-28
-------
Table 5-3, Continued
EadionucHde
Bi-210
Po-210
Ra-226
Ac-227
Ac-228
Th-227
Th-228
Th-230
Th-232
Pa-231
U-232
U-233
U-234
U-235
U-236
U-238
U-240
Np-237
Np-239
Pu-236
Pu-238
Pu-239
Pu-240
Pu-241
Pu-242
Am-241
Am-242m
Am-243
Cm-242
Cm-243
DCFa
rem per
p.Ci • cm"3 • h
O.OE+00
5.1E-03
3.9E+00
7.2E-02
5.5E+02
6.0E+01
1.1E+00
2,21-01
1.1E-01
1.7E+01
1.5E-01
1.4E-01
8.7E-02
8.8E+.01
6.9E-02
5.9E-02
4.1E-01
1.3E+01
9.6E+01
6.8E-02
5.0E-02
4.7E-02
4.9E-02
O.OE+00
4.2E-02
1.1E+01
2.7E-01
2.9E+01
5.6E-02
7.31+01
DRLb
uCi • cm'8 • h
O.OE+00
2.0E+02
2.6E-01
1.4E+01
1.8E-03
1.7E-02
8.9E-01
4.5E+00
9.4E+00
5.8E-02
6.6E+00
7.3E+00
1.1E+01
1.1E-02
1.4E+01
1.7E+01
2.4E+00
7.6E-02
1.01-02
1.5E+01
2.0E+01
2.1E+01
2.0E+01
O.OE+00
2.4E+01
9.2E-02
3.7E+00
3.4E-02
1.8E+01
1.4E-02
5-29
-------
Table 5-3, Continued
Radionuclide
Cm-244
Cm-245
Cm-246
Cf-252
DCF*
rem per
uCi -cm"3 -h
4.8E-02
4.1E+01
4.0E-02
4.3E-02
DRLb
uCi • cm"3 • h
2.1E+01
2.5E-02
2.5E4-01
2.3E-f01
*DCPs are expressed in terms of committed effective dose equivalent and are based on data from
reference (DO-88).
bAssumes a PAG of one rem committed effective dose equivalent.
The contribution from the short-lived daughter is included in the factors for the parent
radionuclide.
5-30
-------
Table 5-4 Dose Conversion Factors (DCP) and Derived Response Levels (DHL) for
Doses Due to Inhalation3 ...... ,
Eadionuclide
H-3
C-14
Na-22
Na-24
P-32
P-33
S-35
Cl-36
K-40
K-42 .
Ca-45
Sc-46
Ti-44
Ą-48
Cr-51
Mn-54
Mn-56
Fe-55
Pe-59
Co-58
Co-60
Ni-63
Cu-64
Zn-65
Ge-68
Se-75
Rb-86
Rb-88
Rb-89
Sr-89
Lung
Class
V°
L ORG Cd
D
D
W
w
W
w
D •'"••-
D
W
Y
Y
W
Y
W
D
D
D
Y
Y
Vapor
Y
Y
W
W
D
D
D
Y
DCF
rem per
uCi -• -cm"3 • h
7.7E+01
2.5E+03
9.2E+03
1.5E+03
1.9E+04
2.8E+03
3.0E+03
2.61-1-04
1.5E+04
.L6E+03
7.9E+03
3.6E+04
1.2E+06
1.2E+04
4.0E+02
8.0E+03
4.5E+02
3.2E+03
1.8E+04
1.3E+04
2.6E+05
7.5E+03
3.3E+02
2.4E+04
6.2E+04
l.OE+04
7.9E+03
l.OE+02
5.2E+01
5.0E+04
DRLb
uCi -cm"8 'h
1.3E-02
4.0E-04
1.1E-04
6.9E-04
5.4E-05
3.6E-04
3.4E.04
3.8E-05
6.7E-05
6.1E-04
1.3E-04
2.8E-05
8.2E-07
8.2E-05
2.5E-03
1.2E-04
2.2E-03
3.1E-04
5.6E-05
7.7E-05
3.8E-06
1.3E-04
3.0E-03 .
4.1E-05
1.6E-05
9.8E-05
1.3E-04
l.OE-02
1.9E-02
2.0E-05
5-31
-------
Table 5-4, Continued.
RadionucHde
Sr-90
Sr-91
Y-90
Y-91
Zr-93
Zr-95
Zr-97
Nb-94
Nb-95
Mo-99
Tc-99
Tc-99m
Ru-103
Ru-105
Ru/Rh-106e
Pd-109
Ag-llOm
Cd-109
Cd-113m
In-114m
Sn-113
Sn-123
Sn-125
Sn-126
Sb-124
Sb-126
Sb-127
Sb-129
Te-127m
Te-129
Lung
Class
Y
Y
Y
Y
D
D
Y
Y
Y
Y
W
D
Y .
Y
Y
Y
Y
D
D
D
W
W
W
W
W
W
W
W
W
D
DCF
rem per
jiCi * cm"3 • h
1.6E+06
2.0E+03
l.OE+04
5.9E+04
3.8E+05
2.8E+04
5.2E+03
5.0E+05
7.0E+03
4.8E+03
l.OE+04
3.9E+01
1.1E+04
5.51+02
5.7E+05
1.3E+03
9.6E+04
1.4E+05
1.81+06
1.1E+05
1.3E+04
3.9E+04
1.9E+04
1.2E+05
3.0E+04
1.4E+04
7.2E+03
7.7E+02
2.6E+04
1.1E+02
DRLb
pCi - cm"3 • h
6.4E-07
5.0E-04
9.9E-05
1.7E-05
2.6E-06
3.5E-05
1.9E-04
2.0E-06
1.4E-04
2.1E-04
l.OE-04
2.6E-02
9.3E-05
1.8E-03
1.7E-06
7.6E-04
l.OE-05
7.3E-06
5.5E-07
9.4E-06
7.8E-05
2.6E-05
5.4E-05
8.4E-06
3.3E-05
7.1E-05
1.4E-04
1.3E-03
3.9E-05
9.3E-03
5-32
-------
Table 5-4, Continued.
Radionuclide
Te-129m
Te-131m
Te-132
Te/I-132*
Te-134
1-125
1-129
1-131
1-132
1-133
1-134
1-135
Cs-134
Cs-136
Cs/Ba-137e
Cs-138
Ba-133
Ba-139
Ba-140
La-140
La-141
La-142
Ce-141
Ce-143
Ce-144
Ce/Pr-144e
Nd-147
Pm-145
Pm-147
Pm-149
Lung
Class
W
w
W
W
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
W
D
D
Y
Y
Y
Y
y
Y
Y
Y
DCF
rem per
uCi * cm"3 • h.
2.9E+04
7.7E+03
1.1E+04
1.2E+04
1,51+02
2.9E+04
2.1E+05
3.9E+04
4.6E+02
7.0E+03
1.6E+02
1.5E+03
5.6E+04
8.8E+03
3.8E+04
1.2E+02
9.4E+03
2.1E+02
4.5E+03
5.8E+03
7.0E+02
3.0E+02
1.1E+04
4.1E+03
4.5E+05
4.5E+05
8.2E+03
3.7E+04
4.7E+04
3.5E+03
DRLb
uCi • cm 3 • h
3.5E-05
1.3E-04
8.8E-05
8.5E-05
6.5E-03
3.4E-05
C8E-06
2.5E-05
2.2E-03
1.4E-04
6.3E-03
6.8E-04
1.8E-05
1.1E-04
2.6E-05
8.2E-03
1.1E-04
4.9E-03
2.2E-04
1.7E-04
1.4E-03
3.3E-03
9.3E-05
2.5E-04
2.2E-06
2.2E-06
1.2E-04
2.7E-05
2.1E-05
2.8E-04
5-33
-------
Table 5-4, Continued.
Radionuclide
Pm-151
Sm-151
Eu-152
Bu-154
Eu-155
Gd-153
Tb-160
Ho-166m
Tm-170
Yb-169
Hf-181
Ta-182
W-187
Ir-192
Au-198
Hg-203
Tl-204
Pb-210
Bi-207
Bi-210
Po-210
Ra-226
. Ac-227
Ac-228
Th-227
Th-228
Th-230
Th-232
Pa-231
U-232
Lung
Class
Y
W .
w
W ,
W ;
D
W
W
w
Y
D
Y
D
Y :
Y
D
D
D
W
D
D
W
D
D
Y
Y
W
W
w
Y
DCF
rem per
uCi • cm."3 • h
2.1E+03
3.6E+04
2.7E+05
3.4E+05
5.0E+04
2.9E+04
3.0E+04
9.3E+05
3.2E+04 .
9.7E+03
1.9E+04
5.4E+04
7.4E+02
3.4E+04
3.9E+03
8.8E+03
2.9E+03
1.6E+07
2.4E+04
1.9E+04
1.1E+07
l.OE+07
8.0E+09
3.7E+05
1.9E+07
4.1E+08
3.9E+08
2.0E+09
1.5E+09
7.9E+08
DRLb
uCi • cm"8 • h
4.8E-04
2.8E-05
3.8E-06
2.9E-06
2.0E-05
3.5E-05
3.3E-05
1.1E-06
3.2E-05
l.OB-04
5.4E-05
1.9E-05
1.3E-03
3.0E-05
2.5E-04
1.1E-04
3.5E-04
6.1E-08
4.2E-05
5.4E-05
8.9E-08
9.7E-08
1.2E-10
2.7E-06
5.2E-08
2.4E-09
2.6E-09
5.1E-10
6.5E-10
1.3E-09
5-34
-------
Table 5-4, Continued,
Radionuclide
TJ-233
U-234
U-235
U-236
U-238
U-240
Np-237
Np-239
Pu-236
Pu-238
Pu-239
Pu-240
Pu-241
Pu-242
Am-241
Am-242m
Am-243
Cm-242
Cm-243
Cm-244
Cm-245
Cm-246
Cf-252
Te/I-132e
1-125
1-129
1-131
Lung
Class
Y
Y
Y
Y
Y
Y
W
w
W
w
w
w
w
w
w
w
w
w
w
w
w
w
Y
W/D
D
D
D
DCP
reni per
uCi • cm"3 • h
1.6E+08
1.6E+08
1.5E+08
1.5E+08
1.4E+08
2.7E+03
6.5E+08
3.0E+03
1.7E+08
4.7E+08
5,21+08
5.21+08
9.91+06
4.9E+08
5.3E+08
5.1E+08
5.3E+08
2.1E+07
3.7E+08
3.0E+08
5.5E+08
5.4E+08
1.9E+08
Thyroid Dose
2.9E+05
9.6E+05
6.9E+06
1.31+06
DRLb
pCi • cm'3 • h
6.21-09
6.3E-09
6.81-09
6.61-09
7.01-09
3.71-04
1.5E-09
3.31-04
5.8E-09
2.11-09
1.9E-09
1.91-09
1.01-07
2.0E-09
1.91-09
2.01-09
1.91-09
4.8E-08
2.7E-09
3.41-09
1.81-09
1.81-09
5.31-09
1.81-05
5.21-06
7.2E-07
3.91-06
5-35
-------
Table 5-4, Continued.
Radiomiclide
1-132
1-133
1-134
1-135
Lung
Class
D
D
D
D
DCF
rem per
uCi • cm"3 • h
7.71+03
2.2E+05
1.3E+03
3.8E+04
DELb
uCi • cm"3 • h
6.5E-04
2.3E-05
3.9E-03
1.3E-04
"These factors and levels apply to adults (IC-75) and are based on Federal Guidance Report No. 11
(EP-88). They are also based on the lung class that results in the most restrictive value. DCFs are
expressed in terms of committed effective dose equivalent, except for those for thyroid dose, which
are In terms of committed dose equivalent.
hDELs are based on a dose of 1 rem committed effective dose equivalent, except those for thyroid
dose radionuclides, which are based on a committed dose equivalent of 5 rem.
*V denotes water vapor.
dL ORG C denotes labelled organic compounds.
"Contributions from short-lived daughters are included in the factors for parent radionuclides.
5-36
-------
Table 5-5 Dose Conversion Factors (DCP) and Derived Response Levels (DRL)
for a 4-Day Exposure to Gamma Radiation from Deposited
Radiomielides*
Radiomielide
H-3
C-14
Na-22
Na-24
P-32
P-33
S-35
Cl-36
K-40
K-42
Ca-45
Sc-46
Ti-44
V-48
Cr-51
Mn-54
Mn-56
Fe-55
Fe-59
Co-58
Co-60
Ni-63
Cu-64
Zn-65
Ge-68
Se-75
Rb-86
Rb-88
Rb-89
Sr-89
DCFb
rem per
pCi * cm • h.
O.OE+00
O.OE+00
8.3E+03
3.1E+03
O.OE+00
O.OE+00
O.OE+00
1.8E-04
5.4E+02
1.8E+02
8.4E-07
7.5E+03
6.7E+02
l.OE+04
1.3E+02
3.3E+03
2.4E+02
8.7E-01
4.2E+03
3.8E+03
8.9E+03
O.OE+00
1.5E+02
2.1E+03
4.5E+00
1.7E+03
3.3E+02
l.OE+01
2.9E+01
5.2E-01
DRLb'c
uCi • cm"3 • h .
O.OE+00
O.OE+00
1.2E-04
3.2E-04
O.OE+00
O.OE+00
O.OE+00
5.4E+03
1.9E-03
5.7E-03
1.2E+06
1.3E-04
1.5E-03
l.OE-04
7.8B-03
3.0E-04
4.1E-03
1.1E+00
2.4E-04
2.6E-04
1.1E-04
O.OE+00
6.8E-03
4.7E-04
2.2E-01
5.9E-04
3.0E-03
9.8E-02
3.4E-02
1.9E+00
5-37
-------
Table 5-5, Continued.
Radionuelide
Sr-90
Sr-91
Y-90
Y-91
Zr-93
Zr-95
Zr-97
Nb-94
Nb-95
Mo-99
Tc-99
Te-99m
Ru-103
Ru-105
Ru/Rh-106d
Pd-109
Ag-llOm
Cd-109
Cd-H3m
In-114m
Sn-113
Sn-123
Sn-125
Sn-126
Sb-124
Sb-126
Sb-127
Sb-129
Te-127m
Te-129
; DCFb
rem per
uCi • cm"3 • h
O.OE+00
3.8E+02
O.OE+00
1.3E+01
O.OE+00
2.9E+03
1.7E+02
6.3E+03
2.9E+03
4.0E+02
2.5E-03
5.3E+01
1.9E+03
2.1E+02
8.3E+02
5.6E-01
1.2E+02
3.7E+01
O.OE+00
3.8E+02
5.9E+01
2.6E+01
l.OE+03
2.4E+02
6.8E+03
9.9E+03
; 1.9E+03
3.7E+02
2.6E+01
3.9E+00
DEL1*5
uCi • cm"3 • h
O.OE+00
2.6E-03
O.OE+00
7.8E-02 .
O.OE+00
3.5E-04
5.8E-03
1.6E-04
3.4E-04
2.5E-03
4.0E+02
1.9E-02
5.2E-04
4.7E-03
1.2E-03,
1.8E+00
8.2E-03
2.7E-02
O.OE+00
2.7E-03
1.7E-02
3.9E-02
l.OE-03
4.1E-03
1.5E-04
l.OE-04
5.2E-04
2.7E-03
3.8E-02
2.6E-01
5-38
-------
Table 5-5, Continued.
Radionuclide
Te-129m
Te-131m
Te-132
Te/I-132d
Te-134
1-125
1-129
1-131
1-132
1-133
1-134
1-135
Cs-134
Cs-136
Cs/Ba-137d
Cs-138
Ba-133
Ba-139
Ba-140
La-140
La- 141
La-142
Ce-141
Ce-143
Ce-144
Ce/Pr-144d
Nd-147
Pm-145
Pm-147
Pm-149
DCFb
rem per
jiCi • cm'3 • h
1.4E+02
3.5E+01
6.6E+02
6.7E+03
3.8E+01
9.5E+02
8.7E+02
1.3E+04
3.1E+03
7.3E+03
1.3E+03
5.7E+03
6.2E+03
7.6E+03
2.4E+03
6.8E+01
1.7E+03
3.2E+00
7.0E+02
4.1E+03
8.9E+00
2.3E+02
3.3E+02
4.8E+02
8.5E+01
2.0E+02
5.2E+02
1.1E+02
1.6E-02
2.8E+01
DRLb'c
pCi • cni 3 • h
7.2E-03
2.8E-02
1.5E-03
1.5E-04
2.7E-02
l.OE-03
1.2E-03
7.4E-05
3.2E-04
1.4E-04
7.5E-04
1.8E-04
1.6E-04
1.3E-04
4.1E-04
1.5E-02
6.1E-04
3.1E-01
1.4E-03
2.4E-04
1.1E-01
4.3E-03
3.0E-03
2.1E-03
1.2E-02
5.0E-03
1.9E-03
8.7E-03
6.2E+01
3.6E-02
5-39
-------
Table 5-5, Continued.
Radionuclide
Pm-151
Sm-151
Eu-152
Eu-154
Eu-155
Gd-153
Tb-160
Ho-166m
Tm-170
Yb-169
Hf-181
Ta-182
W-187
Ir-192
Au-198
Hg-203
Tl-204
Pb-210
Bi-207
Bi-210
Po-210
Ra-226
Ac-227
Ac-228
Th-227
Th-228
Th-230
Th-232
Pa-231
U-232
DCFb
rem per
uCi • cm"3 • h
5.5E+02
2.1E-02
1.5E+01
4.8E+03
2.8E+02
5.0E+02
4.1E+03
6.5E+03
2.4E+01
1.3E+03
2.2E+03
4.8E+03
6.6E+02
3.4E+03
1.1E+03
9.6E+02
5.1E+00
1.2E+01
6.0E+03
O.OE+00
3.4E-02
3.0E+01
8.4E-01
3.3E+02
4.3E+02
1.1E+01
3.6E+00
2.6E+00
1.4E+02
4.1E+00
DRLb>c
uCi • cm"3 • h
1.8E-03
4.9E+01
6.7E-02
2.1E-04
3.5E-03
2.0E-03
2.4E-04
1.5E-04
4.1E-02
7.4E-04
4.5E-04
2.1E-04
1.5E-03
3.0E-04
9.5E-04
l.OE-03
2.0E-01
8.5E-02
1.7E-04
O.OE+00
3.0E+01
3.3E-02
1.2E+00
3.0E-03
2.3E-03
9.2E-02
2.8E-01
3.8E-01
7.1E-03
2.5E-01
5-40
-------
Table 5-5, Continued.
Radiomielide
U-233
U-234
U-235
U-236
U-238
U-240
Np-237
Np-239
Pu-236
Pu-238
Pu-239
Pu-240
Pu-241
Pu-242
Am-241
Am-242m
Am-243
Cm-242
Cm-243
Cm-244
Cm-245
Cm-246
Cf-252
DCFb
rem per
piCi • cm"3 • h
2.0E+00
3.2E+00
6.7E+02
2.9B+00
2.5E+00
3.3E+00
1.3E+02
4.5E+02
3.9E+00
3.4E+00
1.5E+00
3.2E+00
O.OE+00
2.7E+00
1.2E-I-02
1.1E+01
2.6E+02
3.7E+00
5.8E+02
3.3E+00
3.4E+02
2.9E+00
2.5E+00
DBLb'c
uCi • cm"3 • h
5.1E-01
3.1E-01
1.5E-03
3.5E-01
3.9E-01
3.0E-01
7.8E-03
2.2E-03
2.6E-01
3.0E-01
6.7E-01
3.1E-01
O.OE+00
3.7E-01
8.5E-03
9.2E-02
3.8E-03
2.7E-01
1.7B-03
3.1E-01
3.0E-03
3.5E-01
4.0E-01
aEntries are calculated for gamma exposure at 1 meter above the ground surface (DO-88).
bAU radioactivity is assumed to be deposited at the beginning of the incident. Deposition velocities
are taken as 1 em- sec"1 for radioiodines and 0.1 cnv sec"1 for other radionuclides. (See p. 5-24).
"Assumes a PAG of 1 rem committed effective dose equivalent.
''Contributions from short-lived daughters are included in the factors for parent radionuclides.
5-41
-------
References
DO-88 U.S. Department of Energy. External
Dose-Kate Conversion Factors for Calculation
of Dose to the Public, DOE/EH- 0070, U.S.
Department of Energy, Washington (1988).
DO-90 U.S. Department of Energy.
Effectiveness of Sheltering in Buildings and
Vehicles for Plutonium. DOE/EH-0159, U.S.
Department of Energy, Washington (1990).
EP-78a U.S. Environmental Protection
Agency. Protective Action Evaluation Part I -
The Effectiveness of Sheltering as a Protective
Action Against Nuclear Accidents Involving
Gaseous Releases. EPA 520/1-78-001A, U.S.
Environmental Protection Agency,
Washington (1978). ;
EP-78b U.S. Environmental Protection
Agency. Protective Action Evaluation Part II -
Evacuation and Sheltering as Protective
Actions Against Nuclear Accidents Involving
Gaseous Releases. EPA 520/1-78-001B, U.S.
Environmental Protection Agency,
Washington (1978).
EP-88 U.S. Environmental Protection Agency.
Federal Guidance Report No. 11. Limiting
Values of Radionuclide Intake and Air
Concentration and Dose Conversion Factors
for Inhalation, Submersion, and Ingestion.
EPA 520/1-88-020. U.S. Environmental
Protection Agency, Washington (1988).
FD-82 U. S. Department of Health and
Human Services, Food and Drug
Administration. Potassium Iodide as a
Thyroid-Blocking Agent in a Radiation
Emergency: Final Recommendations on Use.
Federal Register. 47, 28158; June 29, 1982.
FE-85 Federal Emergency Management
Agency. Federal Radiological Emergency
Response Plan. Federal Register. 50. 46542;
November 8, 1985.
HA-75 Hans, J.M. Jr., and Sell, T.C.
Evacuation Risks - An Evaluation.
EPA-520/6-74-002, U.S. Environmental
Protection Agency, Washington, (1975).
IC-75 International Commission On
Radiological Protection. Report of the Task
Group on Reference Man. ICRP Publication
23, Pergamon Press, New York, (1975).
NR-75 U.S. Nuclear Regulatory Commission.
An Assessment of Accident Risks in U.S.
Commercial Nuclear Power Plants.
WASH-1400, U.S. Nuclear Regulatory
Commission, Washington, (1975).
NR-78 U.S. Nuclear Regulatory Commission
and U.S. Environmental Protection Agency.
Task Force Report. Planning Basis for the
Development of State and Local Government
Radiological Emergency Response Plans in
Support of Light Water Nuclear Power Plants.
NUREG-0396 or EPA-520/1-78-016, U.S.
Environmental Protection Agency,
Washington, (1978).
NR-80 U.S. Nuclear Regulatory Commission.
Criteria for Preparation and Evaluation of
Radiological Emergency Response Plans and
Preparedness in Support of Nuclear Power
Plants. NUREG-0654, FEMA-REP-1, Rev.l.,
Washington, (1980).
NR-88 U.S. Nuclear Regulatory Commission.
A Regulatory Analysis on Emergency
Preparedness for Fuel Cycle and Other
Radioactive Material Licensees. NUREG-
1140, U.S. Nuclear Regulatory Commission,
Washington, (1988).
NR-89 U.S. Nuclear Regulatioy Commission.
Appendix E - Emergency Planning and
Preparedness for Production and Utilization
Facilities. Title 10, CFR Part 50, U.S.
Nuclear Regulatory Commission, Washington,
(1975).
NR-89a U.S. Nuclear Regulatory Commission.
Severe Accident Risks: An Assessment for
Five U.S. Nuclear Power Plants. NUREG-
1150, U.S. Nuclear Regulatory Commission,
Washington, (1990).
5-42
-------
CHAPTER 6
Implementing the PAGs for the Intermediate Phase
(Food and Water)
See Chapter 3 and Appendix D for Current Implementation
Eecommendations for Food. Also refer to the
following documents:
Federal Emergency Management Agency
Guidance Memorandum IN-1, The Ingestion Exposure
Pathway. February 26, 1988 Federal Emergency
Management Agency. Washington, DC 20472
Guidance on Offsite Emergency Radiation Measurement Systems
Phase 2, The Milk Pathway, FEMA REP-12, September 1987.
Guidance on Offsite Emergency Radiation Measurement Systems.
Phase 3, Water and Non-Dairy Food Pathway, September 1989.
6-1
-------
Page Intentionally Blank
-------
HHS Publication FDA 82-81%
Background for Protective Action
Recommendations: Accidental
Radioactive Contamination of
Food and Animal Feeds
B. Shleien, Pharm.D.
G.D. Schmidt
Office of the Bureau Director
and
R. P. Chiacchierini, Ph.D.
Division of Biological Effects
BRH
WHO Collaborating Centers fort
• Standardization of Protection
Against Nonwnizing Radiations
* Training and General Tasks in
Radiation Medicine
* Nuclear Medicine
August 1982
U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES
Public Health Service
Food and Drug Administration
Bureau of Radiological Health
Rockville, Maryland 20857
-------
FOREWORD
The Bureau of Radiological Health develops and carries out a national program to
control unnecessary human exposure to potentially hazardous ionizing and nonionizing
radiations and to ensure the safe, efficacious use of such radiations. The Bureau publishes
the results of its work in scientific journals and in its own technical reports.
These reports provide a mechanism for disseminating results of Bureau and contractor
projects. They are distributed to Federal, State, and local governments; industry; hos-
pitals; the medical profession} educators; researchers; .libraries; professional and trade
organizations; the press; and others. The reports are sold by the Government Printing
Office and/or the National Technical Information Service.
The Bureau also makes its technical reports available to the World Health Organization*
Under a memorandum of agreement between WHO and the Department of Health and
Human Services, three WHO Collaborating Centers have been established within the Bureau
of Radiological Health, PDAs
WHO Collaborating Center for Standardization of Protection Against Nonionizing
Radiations;
WHO Collaborating Center for Training and General Tasks in Radiation Medicine; and
WHO Collaborating Center for Nuclear Medicine.
Please report errors or omissions to the Bureau. Your comments and requests for
further information are also encouraged.
John C. VUlf or
jirector
Bureau of Radiological Health
-------
PREFACE
By FEDERAL REGISTER action of March 11, 1982 (47 FR 10758), the Federal Emer-
gency Management Agency (FEMA) outlined the responsibilities of several Federal agencies
concerning emergency response planning guidance that the agencies should provide to State
and local authorities. This updated a prior notice published in the FEDERAL REGISTER by
the General Services Administration (GSA) on December 24, 1975 (40 FR 59494), on the
same subject. GSA responsibility for emergency management was transferred by Executive
Order to FEMA. The Department of Health and Human Services (HH5) is responsible for
assisting State and local authorities in developing plans for preventing adverse effects from
exposure to radiation in the event that radioactivity is released into the environment. This
includes developing and specifying protective actions and associated guidance to State and
local governments for human food and animal feeds.
Proposed recommendations were published in the FEDERAL REGISTER on December 15,
1978 (43 FR 58790) and a background document accompanied their publication. Twenty-one
comment letters were received in response to the proposal in addition to comments from
various Federal agencies. Review of these comments led to changes in the recommenda-
tions and supporting rationale, dosimetric and agricultural models, and cost/benefit analysis.
These changes have been incorporated into this.background document, which is intended to
accompany and support FDA's final recommendations on Accidental Radioactive
Contamination of Human Foods and Animal Feeds: Recommendations for State and Local
Agencies. The final recommendations will appear in the FEDERAL REGISTER.
This background report discusses the rationale for the Protective Action Guides; the
dosimetric and agricultural models used in their calculation; some methods of analysis for
radionuclide determination; appropriate protective actions; and cost considerations.
Bernard Shleien, Pharm. D.
Assistant Director for
Scientific Affairs
Bureau of Radiological Health
111
-------
ABSTRACT
Shleien, B., G.D. Schmidt, and R.P. Chiacchierini. Background for Protective Action
Recommendations: Accidental Radioactive Contamination of Food and Animal Feeds. HHS
Publication FDA 82-8196 (August 1982) (pp.
This report provides background material for die development of FDA's
Protective Action Recommendations: Accidental Radioactive Contamination
of Food and Animal Feeds. The rationale, dosime trie and agricultural transport
models for the Protective Action Guides are presented, along with information
on dietary intake. In addition, the document contains a discussion of field,
methods of analysis of radionuciides deposited on the ground or contained
in milk and herbage. Various protective actions are described and evaluated,
and a cost-effectiveness analysis for the recommendations performed.
The opinions and statements contained in this report may not
necessarily represent the 'views or the stated policy of the World
Health Organization (WHO). The mention of commercial products,
their sources, or their use in connection with material reported
herein is not to be construed as either an actual or implied
endorsement of such products by the Department of Health and
Human Services (HHS) or the World Health Organization.
IV
-------
CONTENTS
Page
Foreword ii
Preface iii
Abstract iv
Chapter 1. Rationale for Determination of the Protective Action Guides .... 1
1.1 Introduction . . . . . . . . . . ...... 1
1.2 Models for Evaluation of Risk . ................... 1
1.2.1 Somatic Risk Evaluation 1
1.2.2 Genetic Risk Evaluation ................... 2
1.3 Assessment of Common Societal and Natural Background
Radiation Risks. . . . 3
1.3.1 Common Societal Risks 3
1.3.2 Risks from Natural Radiation . . 4
1.it Preventive and Emergency PAG's. . . 5
1.4.1 Preventive PAG 6
1.4.2 Emergency PAG. 7
1.5 Evaluation of PAG Risks 7
Chapter 2. Oosimetric Models, Agricultural Transport Models,
Dietary Intake, and Calculations . » S
2.1 Dosimetrie Models 8
2.1.1 Introduction 8
2.1.2 Iodine-131: Dose to Thyroid 8
2.1.3 Cesium-137 and-13*: Dose to Whole Body . .... . . .... 9
2.1.4 Strontium: Dose to Bone Marrow ............... 10
2.1.5 Other Radionuclides 11
2.2 Agriculture Transport Models » 12
2.2.1 Transport Models 12
2.2.2 Total Intake 13
2.2.3 Peak Concentration 14
2.3 Dietary Intake 14
2.4 Calculations 15
-------
Page
Chapter 3. Methods of Analyses for Radionuclide Determination . 18
3.1 Introduction 18
3.2 Determinations of Radionuciide Concentrations by
Sensitive Laboratory Methods. . , . . 18
3.3 Determinations of Radionuclide Concentrations by Field Methods .... 19
3.3.1 Ground Contamination (Beta Radiation) » 19
3.3.2 Herbage . 20
3.3.3 MUk. 21
Chapter 4. Protective Actions 26
Chapter 5. Cost Considerations 31
5.1 Cost/Benefit Analysis 31
5.1.1 Introduction 31
5.1.2 Benefit of Avoided Dose 32
5.1.3 Protective Action Costs 32
5.1.* Population Milk Intake and Dose 33
5.1.5 Milk Concentration for Cost 3 Benefit . 33
5.2 Economic Impact 35
5.3 Cost-Effectiveness Analysis 37
5.4 Summary and Conclusion 38
References 39
VI
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CHAPTER 1. RATIONALE FOR DETERMINATION OF THE
PROTECTIVE ACTION GUIDES
1.1 INTRODUCTION
The process of determining numerical limits far radiation standards is one of risk
assessment. This process, in which risk considerations are an important factor in decision-
making, consists of two elements: determination of the probability that an event will occur,
and determination of "acceptable risk." A recent discussion of acceptable risk defines risk
as a measure of the probability and severity of adverse effects. Safety is the degree to
which risks are judged acceptable (1).
Since initiation of protective action assumes that an accident has occurred, no
attention will be given to the estimation of probabilities for accident occurrence in the
present analysis.
One process of determining "acceptable risk" is to compare estimates of risk associated
with an action with already prevalent or "natural" risks that are accepted by society.
This method of evaluation is employed in the present discussion by comparing the risk
from natural disasters and from the variation in "natural radiation background1' to the-
radiation risk associated with the numerical limits for the Protective Action Guides (PAG).
"Protective action guide" (PAG) means the projected dose commitment values to
individuals in the general population that warrant protective action following a release of
radioactive material. Protective action would be warranted if the expected individual dose
reduction is not offset by negative social, economic, or health effects. The PAG does not
include the dose that has unavoidably occurred prior to the assessment. "Projected dose
commitment" means the dose commitment that would be received in the future by indi-
viduals in the population group from the contaminating event if no protective action
were taken. The projected dose commitment is expressed in the unic of dose equivalent or
the rem.
The "natural radiation background" consists of contributions from external radiation
and internal deposited radioactivity from ingestion and inhalation. For the most part, the
variation in the internal natural radiation dose is due to the variability of whole-body
potassium-40. Since these PAG's are limited to ingestion, a parameter that describes the
variability of the internal natural radiation dose might appear more appropriate than using
the variability of the external or total natural radiation dose in evaluating the acceptability
of a given level of risk. However, the potassium level in the body (and hence internal dose)
is controlled by metabolic processes and dietary intake has little effect. Hence the risk of
natural disasters, which is dependent on geographical location of residence, is in this
agency's opinion a better measure of acceptable risk.
1.2 MODELS FOR EVALUATION OF RISK
Models for the somatic and genetic effects of radiation are required for comparisons of
radiation risks from the PAG's relative to other naturally occurring risks.
1.2.1 Somatic Risk Evaluation
A review of the current literature indicates that the risk estimates developed In che
National Academy of Science Commie tee on the Biological Effects of Ionizing Radiation or
the BEIR-I report (2) and the BEIR-III report (3) are appropriate for use in analysis of
1
-------
somatic risk. Mortality rather than incidence estimates are employed in the comparisons.
In the case of comparisons to natural background radiation, use of mortality data or
incidence estimates would yield the same numerical PAG limits, because these limits are
based on a comparison between risks rather than an evaluation of absolute risk.
The radiation doses in the event of a contaminating accident will most likely result from
ingestion of the fission products cesium-13* and -137} strontium-89 and -90} and iodine-131.
For the purpose of this analysis it is assumed that all projected extra cancers can be
attributed to internal radiation via the food pathway (i.e., the risks from ingested
radioactive material is the same as that fro.n external radiation).
The BEIR-m (3) best estimate of lifetime cancer risk (linear quadratic model) for a
single exposure to low-dose, low LET radiation is from 0.77 to 2.26 x 10"* deaths per person-
rem, depending on whether the absolute or relative-risk projection model is used (calculated
from Table 1). The equivalent risk estimate from BEIR-I (2) is i.17 to €.21 x 10*** deaths
per person-rem.
Table 1. Risk estimates for single dose
Deaths per million persons per10
rads single dose whole-body BEIR-III
Dose response model Absolute risk Relative risk
Linear quadratic
Linear
Quadratic
766
1671
95
2255
5014
276
These risk estimates are for a single dose of 10 rem, because limitations of the scientific
information do not justify estimates at lower closes according to die BEJR Committee.
Because of the uncertainty of risk estimates at low doses, BEIR-III provided risk estimates
based on a linear model and a pure quadratic dose response model as well as estimates based
on the preferred linear quadratic model. The risk estimates for the linear model are about
a factor of 2 higher and those of the quadratic model and about a factor of 8 lower than
those of the linear quadratic model. It should further be noted, that BEIR-III does not
recommend that their risk estimates be extrapolated to lower doses because of the
inadequacies of the scientific basis. BEIR-III does recognize however that Federal agencies
have a need to estimate impacts at lower doses. While BEIR-III prefers the linear-quadratic
dose response model as the best estimate, regulatory agencies have continued to favor the
linear model as the basis for making risk estimates. While die BEIR-III estimates will be
used here to estimate the impact (health effects) at lower doses, it is fully recognized
that current scientific opinion leaves alternatives as to which dose response and risk model
to use.
As previously stated, for the purpose of setting PAG's, comparison of radiation risks to
those from natural disasters is considered the approach of choice in this document.
1.2.2 Genetic Risk Evaluation
The model for genetic risks from radiation exposure is described in the BEIR-III report
(3). In the first generation, it is estimated that 1 rem of parental exposure throughout the
general population will result in an increase of 5 to 75 additional serious genetic disorders
per million liveborn offspring. The precision for estimating genetic risks is less precise than
those for somatic risks. Given the broad range, genetic risks are evaluated, but are not
precise enough to be a basis for setting the PAG's.
-------
1.3 ASSESSMENT OF COMMON SOCIETAL AND NATURAL BACKGROUND RADIA-
TION RISKS
1.3.1 Common Societal Risks
As previously stated, one method of determining the acceptability of a risk is by
comparing prevalent or normal risks from hazards common to society. A list of the annual
risks from common societal hazards is given in Table 2. Comparision of radiation risks to
commonly accepted societal risks Assumes that the age dependencies are similar and that all
individuals are equally exposed tr the hazard. This latter assumption is, of course, not
entirely valid in that persons near-ir a nuclear power plant or a dam, or in an earthquake or
tornado area might be expected to be at greater risk than persons living at a distance from
the particular hazard.
Table 2. Annual risk of death from hazards common to society
Risk of death
Category Reference (per person per year)
All disease
Leukemia and all other cancer
Motor vehicle accidents
Accidental poisoning
Air travel
Tornadoes (Midwest)
Earthquakes (Calif. )
Floods (46 million at risk)
Catastrophic accidents
(tornadoes, floods,
hurricanes, etc.)
Natural disasters
Tornadoes
Hurricanes
Floods
Lightning
Winter storms
(4)
(5)
(6)
(6)
(7)
(8)
(8)
(9)
(10)
Ml)
(6)
(7)
(9)
(7)
(9)
(8)
(9)
(7)
(9)
8 x 10-3
1.5 x 10-3
3 x 10-"
1 x 10's
9 x lO'6
2 x 10-5
2 x 10-fr
2.2 x 10-$
1.2 x 10'6
9 x lO'7
8 x I'7
0.* x 10"s
0.6 x 10-6
0.* x 10~s
0.3 x 10'6
2 x 10'6
0.5 x 10'*
0.5 x 10-s
0.* x 10-6
.6
Natural disasters (sum of above) 2.1 to 3.9 x 10
Table 2 indicates that the annual individual risk from natural disasters is approximately
1 to 4 x 10~s. This risk represents a common risk level, which is generally not considered
in selecting place of residence. At this level of risk, some action to prevent further loss of
life could be expected by society following the occurrence of a natural disaster. It thus
appears prudent to evaluate the somatic risks from radiation in relation to the risk of death
from a natural disaster. For comparison purposes, a value of 1 in a million (1 x 10"8) annu-
al risk of death, which is often quoted as art acceptable risk, will be used as the risk of
natural disasters. Actual data indicate chat the risk of natural disasters may be a 2 or 3
times greater risk than this value. For a risk of death of 1 x 10~s per year, the lifetime
accepted societal risk would be about 70 x 10~6. This is equivalent to a single radiation
dose of 1*0 to 420 mrem, using the linear model, or 310 to 910 mrem using the BEIR-III
linear quadratic model (see Table 1). The upper and lower ranges are those obtained from
employment of relative and absolute risk models and the dose response extrapolations
mentioned above (from calculations based on data in Table 1). Genetic effects are not
considered in evaluating common societal hazards because of the difficulty in assessing
-------
deaths occurring from genetic consequences, either natural or radiation induced. If sponta-
neous abortions are deleted from this category, then fatal genetic effects are a small
portion of the overall genetic impact on health. However, it is difficult to accurately
evaluate genetic effects, and even more difficult to compare its impact to the impact of
somatic effects in an effective manner.
1.3.2 Risks From Natural Radiation
Further perspective on acceptable risk can be obtained by examining the risks of natural
background radiation. In risk assessments where a radiation risk is compared to that from
the natural radiation background, the question is which variable associated with natural
background should be used to determine "acceptable risk?" Since background radiation has
always been a part of the natural environment, a plausible argument might be to assume
chat the risks associated with the average natural radiation dose represent an "acceptable
risk."
It has also been argued that because of the ever present risk from natural radiation, a
level of manmade radiation ought to be acceptable if it is "small" compared to natural
background (12). It has been suggested that "small" be taken as the standard deviation of
the population-weigh ted natural background (13). In previous evaluations chat led to the
FDA's proposed PAG recommendations (14) the geographic variable (two standard
deviations) in the natural radiation dose was used as a point of comparison for judging
acceptable radiation risk (15). This value, calculated on a S cate-by-S cate basis assuming a
'"log-normal distribution and not weighted for population, Is 8.5 mrem per year. The
cumulative lifetime: dose equivalent would thus bis about 500 mrem, which was the basis for
the proposed PAG recommendation for the whole body at the Preventive PAG level. The
Environmental Protection Agency (EPA), in a further analysis of previously published data
(16), has calculated the cumulative distribution of dose equivalent in the U.S. population.
These data show that 95 percent of the population receives between 28 and 84 mrem/year
from cosmic and terrestrial background radiation (17). The actual distribution is
asymmetric and not log-normal. Thus, one-half of this 95-percent increment range, or 23
mrem/year, will be taken as the value for judging acceptable risk. Adler (13) notes that one
standard deviation of the natural external and internal radiation background derived from
earlier sources (18) is 20 mrem. Personal conversations with Adler revealed that this
estimate is based on air exposures rather than dose equivalent (mean whole body) and
involved a broad rounding off of values. At the 95-percent increment value (latest EPA
data) of 28 mrem/year (19), die additional lifetime dose over 70 years is about 2000 mrem.
About 6 million persons (2-1/2 percent of the population) receive lifetime doses that exceed
the mean background radiation dose by this amount or more.
Another possibility, especially applicable to setting limits for internal emitters, is using
the variation in internal natural radiation dose as a reference for establishing an acceptable
standard for PAG's. For PAG limits for radionuclides via the ingestion pathway, doses to
organs other than the lungs are most pertinent. Using this suggestion still requires a
judgmental decision as to whether the variation in internal natural radiation dose is "small."
A summary of internal natural radiation doses is given in Table 3. It is apparent that
natural radiation doses to human tissues and organs is determined mainly by potassium-40
concentration. The average annual internal whole-body radiation dose per person from
ingested natural radioactivity is 19.6 mrem, of which 17 mrem is due to potassium-40.
In potassium-40 whole-body measurements of 10,000 persons, a standard deviation of
about 12 percent (95-percent confidence level of 23.52 percent) was observed (20). The
study further concluded that the standard deviation is also the same for different groups of
age and sex, and therefore, it may be concluded that the same biological variation exists for
all the different age-sex groups. In another study based on the chemical determinations of
total body potassium the average amount in a 70-kg man was estimated to be 136 g with a
standard deviation of ± 28 g or ±20 percent (95-percent confidence increment of ±40
percent) (21).
-------
Table 3. Annual internal radiation dose per person
for non-inhaled natural radioactivity3
Annual dose (mrads/year) whole-body average
(unless otherwise noted)
H-3
Be-7
C-l*
Na-22
K-40
Rb-87
U-238-U-234 series
Ra-222
Po-210
Ra-226
Th-230
Th-232
0.001
0.008
1.3
0.02
17
0,*
0.0^3b
Q.064b
0.7
0.031b
O.Qv3
0.0*b
Total 19.65
fUNSCEAR(1977).
°Based on soft tissue dose (lung, testes, and ovaries)
An indirect means of determining the variability of whole-body potassium values is
based on the constant ratio of mean potassium values co total body water up to age JO
(20). The 95-percent confidence increment for the variability of total body water in males,
ages 16 to 90 is 16 percent, while for females it is 13 percent for ages 16 to 30 and 21
percent for ages 31 to 90 (22).
From the above data, it appears that the increment for the 95-percent confidence
level for whole-body potassium, and hence potassium-40, is between Ł15 percent and ± 40
percent. Note that this variability may be due to differences in body water or body weight^.
Only in the case of one study (21) is it clear the total body weight is considered a constant*
It is apparent that a range of values between approximately 3 to 7 mrad per year may be
used to describe the variability in natural potassium-40 dose to the population on a whole-
body dosimetric basis. The mid-point of this range is 5 mrad per year or a lifetime dose
commitment (70 years) of 350 mrem.
Thus, the lifetime radiation dose associated with the variability in natural radiation is
about 350 mrem (internal) and 2000 mrem (external).
1.4 PREVENTIVE AND EMERGENCY PAG'S
PAG's have been proposed for two levels of response:
1. Preventive PAG - applicable to situations where protective actions causing
minimal impact on the food supply are appropriate. A preventive PAG establishes a level at
which responsible officials should take protective action to prevent or reduce the
concentration of radioactivity in food or animal feed.
2. Emergency PAG - applicable to incidents where protective actions of great impact
on the food supply are justified because of the projected health hazards. An Emergency
PAG establishes a level at which responsible officials should isolate food containing
radioactivity to prevent its introduction into commerce, and at which the responsible offi-
cials must determine whether condemnation or another disposition is appropriate.
-------
1.4.1 Preventive PAG
During recent years numerous reports on risks and risk/benefit assessments for the
evaluation of technological insults have been published. A number of these have concluded
thac an annual risk oi death of 1 in a million is acceptable to the public (8). The total aver-
age annual risk to the U.S. population from natural disasters appears to be about 2 or 3
times greater than the 1 in a million annual risk. Those individuals living in certain flood
plains, tornado, or earthquake areas accept risks that may be greater than the average by a
factor of 2 or more (See data for tornadoes and earthquakes in Table 2).
As previously mentioned, based on BEIR-UI (3) upper risk estimates, a 1 in a million annu-
al risk of death corresponds to a single radiation dose of 140 to 910 mrem.
It is our conclusion that an annual risk of 1 in a million provides a proper perspective for
setting food protective actions guides (PAG's) for radiation contamination accidents of low
probability. It appears that most individuals in the United States will never be exposed to
such a radiation contamination accident and that any one individual is not likely to be
potentially exposed more than once in his lifetime.
Based on the above considerations, the uncertainty in radiation risk estimates and the
uncertainty in the average natural disaster risks, a value of 0.5 rem whole body is selected
for the Preventive PAG* Thus* at projected doses of 0.5 rem from contaminated food, it is
recommended thac protective actions having low impacts be taken for protection of the
public. The specific value of 0.5 i'em represents a judgment decision rather than a specifi-
cally derived value from specific models and assumptions.
Further perspective on acceptable risks for setting the PAG's is the risks associated with
natural background radiation. The discussion above indicates that lifetime dose associated
with the 95-percent increment of the variability in natural radiation is about 350 mrem
internal and 2000 mrem external (that is, 2-1/2 percent of the population receives doses
greater than the average by this amount or more).
This Preventive PAG Is applicable to whole-body radiation exposure and to major
portions of the body including active marrow (ingestion of strontium) in conformity with
current U.5. radiation protection practice. Coincidently, 0.5 rem is the Federal Radiation
Council's (FRC) annual limit for individuals of die general population (23).
Present convention, recommended by the Federal Radiation Council (23) based on prior
estimates of relative radiation risks for various organs indicates that radiation limits for the
thyroid gland be set at 3 times those for the whole body. More recent scientific information
indicates that the risks from organ doses relative to whole body differ from those assumed
when the current U.S. regulations and FRC guidance were established. The International
Commission on Radiological Protection (ICRP) in revising its recommendations on internal
exposure derived weighting factors that represent the ratio of risk from irradiation to a
given tissue (organ) to the total cancer risk due to uniform irradiation to the whole body.
The ICRP weighting factors are 0.12 for red bone marrow and 0.03 for thyroid, indicating
that the cancer risk is 8 times less for red bone marrow and 33 times less for thyroid than
for whole body exposure (24). Further considerations of effects other than cancer resulted
in the limitation of organ doses to 50 rems per year for occupational workers. Thus the
ICRP recommendations in effect provide for or allow single organ doses that are 8 times
greater for red bone marrow and 10 times greater for thyroid than lor whole body. The EPA
has recently proposed Federal guidance for occupational radiation protection that incorpo-
rates the basic ICRP recommendations (46 FR 7836, 3 an. 23, 1980). Setting the Preventive
PAG at 0.5 rem for whole body and red bone marrow and 1.5 rem for thyroid provides
significantly more protection from the actual risks of organ doses than from whole-body
risks. To the extent that the whole-body risk is considered acceptable, the red bone marrow
and thyroid limits are conservative by factors_of 8 and 3.3, respectively.
-------
1.4.2 Emergency PAG
The philosophy of the protective action guidance of FDA is that low impact protective
actions should be initiated when contamination of food exceeds the Preventive PAG. The
intent is that such protective actions be implemented to prevent the appearance of
radioactivity in food at levels that would require the condemnation of food. If such actions
are ineffective, or high levels appear in food, then the Emergency PAG is that level at
which higher impact (cost) protective actions are warranted. At the Emergency PAG
radiation level, action should be taken to isolate and prevent the introduction of such food
into commerce and to determine whether condemnation or other disposition is appropriate.
With regard to the numerical relationship between the Preventive PAG level and the
Emergency PAG level, prior conventions may be considered. For example, the Federal
Radiation Council (23) assumed that the dose to the most highly exposed individual does not
vary from the average dose to the whole population by a factor greater than three; Hence, a
factor of 3 was used to define the difference between maximum and average population
limits. Traditionally, it has been more common to use a factor of 10 as a safety factor,
such as between occupational and general public limits. A factor of 10 difference between
the Emergency and Preventive PAG levels, based on these traditional radiation protection
approaches has in the past been thought to introduce a sufficient level of conservatism. The
proposed PAG's (14) adopted this rationale in setting the Emergency PAG's. The analyses of
costs, to follow, also indicate that a factor of 10 between the Preventive PAG and
Emergency PAG is appropriate. As calculated in the last chapter of this report the cost of
condemnation of milk (high impact protective action) is about a factor of 10 greater than
the- cost of using uncon laminated stored feed (low impact protective action). Since
contamination of the milk pathway is considered to be the most probable and significant
food problem, this is the only pathway that is cost analyzed.
The use of a factor of 10 adopted here results in an Emergency PAG of 5 rem for the
whole body which numerically is equivalent to the current occupational annual limit. This
limit permitted each year over a working lifetime is associated with the expectation of
minimal increased radiation risks.
1.5 EVALUATION OF PAG RISKS
The risks associated with a radiation dose equal to the PAG's can be readily calculated
from the BEIR-HI risk estimates in Table 1. For the Preventive PAG of 0.5 rem, the deaths
per million persons exposed are one-twentieth of those given for the 10-rad single dose (or
about 38 to 250 deaths for the linear quadratic and linear models respectively). On an
individual basis, this is a risk of death of 0.38 to 2.50 x 10"* (0.0038 to 0.025 percent)
over a lifetime. BEER-HI gives the expectation of cancer deaths in the U.5. population
as 167,000 per million or an individual expectation of cancer death of 16.7 percent.
As noted above, the BEIR-QI estimate of serious first generation genetic disorders is 5 co
75 per million live offspring per rem of parental exposure. Thus, for a dose of 0.5 rem, the
expectation is 2.5 to 38 disorders per million live offspring. BEIR-III notes the current
estimate of the incidence of serious human disorders of genetic origin as roughly 10 percent
of liveborn offspring.
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CHAPTER 2. DOSIMETRIC MODELS, AGRICULTURAL TRANSPORT MODELS,
DIETARY INTAKE, AND CALCULATIONS
2.1 DOSIMETRIC MODELS
2.1.1 Introduction
The dosimetric models and metabolic parameters for estimating the dose from internally
deposited radionuciides are In a state of flux. The recent reports and current activity
represent the first major revision since the adoption of ICRP Publication 2 (23) and NCRP
Report 22 (26) in 1959. ICRP Publication 30 (27) superseded ICRP Publication 2 and revised
the basic approach in setting limits for intake of radionuciides by workers. The ICRP recom-
mendations are intended to avoid nonstochastic effects and to limit the occurrence of
stochastic effects to an acceptable level. This approach includes the use of weighting
factors to sum the risk from organ doses in setting the limits for intakes. This system
contrasts with the earlier approach where limits were based on the dose to the "critical
organ." '.
The ICRP Publication 30 approach has considerable merit, but is not yet widely accepted
In the United States. Its use in calculating the derived response levels would represent a
major change. Accordingly, the approach is to use the organ to whole-body dose relation-
ship of current U*S. regulations and to select critical organ dose conversion factors that are
based on current dosimetric models and metabolic parameters. Where apropriate, the
recent ICRP and NCRP organ dose models will be accepted as representing current scientif-
ic opinion. It should be noted that future reports and revisions by NCRP, MIRD (Medical
Internal Radiation Dose Committee of The Society of Nuclear Medicine) and other Federal
agencies may necessitate a revision of the dose conversion values selected here.
The PAG's are applicable to the most critical or sensitive segment of the population. In
most cases this means that the infant or child is the critical segment. In che case of the
Emergency PAG, derived response levels are also presented for che adults. This permits
greater flexibility in the choice of protective actions in cases where infants are not present
or can be excluded from use of the specific food item being considered.
2.1.2 Iodine-131: Dose To Thyroid
Fetal uptake of iodine begins at about the 9th week of gestation and reaches a maximum
in the newborn infant (28,29) before returning to adult levels. Kereiakes et al. (30) report
that thyroid uptake during the first 2 weeks of life is very high and report a value of 70
percent of that administered for the newborn. The radioiodine uptake expressed per unit
thyroid weight remains high for the newborn and infant and only gradually decreases
throughout childhood and adolescence to adult levels. The newborn infant will be taken as
che most critical segment of che population because factors concerning intake, uptake, and
radiosensitivity indicate that the thyroid gland of an infant receives a higher radiation dose
per unit 1-131 ingested than any other age group (30). However, it is interesting to note that
data indicate chat only about 3 percent of infants are given whole cow's milk at 1 month of
age and about 1 percent at 10 days (31). Hence, assuming that all infants are given whole
milk provides a conservative estimate of inf anc thyroid doses.
Data on the dose to the fetal thyroid from 1-131 ingested by the mother is rather limit-
ed. The study of Dyer and Brill (29) reports an increase in the fecal thyroid dose from 0.7 to
5.9 rads per uCi administered to the mocher for fetal ages of 13 to 22 weeks. It thus
-------
appears that the fetal thyroid dose is less than that of the newborn infant ingesting 1-131
contaminated milk.
The current literature on normal thyroid uptake in U.S. adults shows 24-hour uptake has
decreased from about 30 percent reported in the 1960's to about 20 percent or less in cur-
rent comparable studies. Kereiakes et aJ. (32) use a 20-percent uptake for all ages. This
reduced uptake apparently results from changes in the U.S. diet, whereas ICRP 30 (27) has
continued to use an uptake of 30 percent to reflect world averages.
The Medical Internal Radiation Dose (MIRD) Committee schema (33) has be m used by
WeUman and Anger (34) to calculate dose factors per uCl ingested for the newborn for the
1-, 5-, 10-, and 15-year-old child, and for the adult. These factors were then modified by
Kereiakes et al. (32) to reflect a 20-percent uptake for all ages. A biological half-life of 68
days is used for ail ages, which results in an effective half-life of 7.2 days. Although there
is some evidence that the biological half-life for the infant is less, the radiation dose is
largely controlled by the radiological half-life and use of a single value appears appropriate
here. Because of some uncertainty regarding the fetal thyroid dose and lack of acceptance
by national and international groups, the older data (27-percent uptake) of Wellman and
Anger (34) will be used. This provides some additional conservatism in the derived response
levels for 1-131. The cumulative activity is 2.0S pd-days per uCi ingested
(administered).
Table 4. Summary of 1-131 dose conversion factors
Age
Newborn
1 yr.
5 yrs.
10 yrs.
15 yrs.
Adult
Thyroid weight (i)
1.3
2.2
4.7
S.O
11.2
16.0
Dose rad/ uCi
16.0
10.?
5.1
3.0
2.1
1.5.
For the infant and adult, the dose conversion factors to be used are 16.0 and 1.5 rad/ yCi
ingested.
2.1.3 Cesium-137 and -134: Dose To Whole Body
The NCRP (35) has reviewed the behavior of Cs-137 in the environment and its metabo-
lism and dose to man. From studies of Cs-137 in food chains, the biological half-life is
found to vary from 15 ±5 days in infants to 100 ±5 days in adults. The biological half-
life in pregnant women is reported to be 1/2 to 2/3 that in nonpregnant women and
consequently the dose to the fetus is also reduced.
Retention of Cs-137 in the adult is stated to be well represented by a 2-exponential
equation with biological half-times of 1.4 days and 135 days applicable to retention in body
fluid and soft tissues, respectively. Integration of this equation yields an accumulated activ-
ity of 170 uCi-days per pCi of intake. This accumulated activity may be expressed in
terms of a single retention function yielding a value of US days.
The dosimetry of internally deposited Cs-137 in infants and adults is treated separately
for the beta particle and photon components. The difference between infants and adults is a
smaller photon contribution to the infant because of the smaller body size. For a uniform
concentration of 1 uCi/kg of body weight, the total beta and photon dose rate is If
mrad/day to the infant and 25 mrad/day to the adult. Use of the above accumulated activ-
ity factor of 170 ^Ci-days per yCi intake yields a dose of 0.061 rmd/ uCl intake for the
adult. Assuming an effective retention time of 20 days for the infant, the corresponding
factor for the infant is 0.071 rad/uCi intake. The use of a smaller effective retention
-------
time (15 days as noted in NCRP (26)) or 10 days as used in NUREG-0172 (36) would reduce
che Infant dose conversion factor. The use of 20 days thus tends to overestimate the infant
dose.
It is also important to consider the dose from Cs-134 which, depending on operating
history, occurs in nuclear reactor fuel at levels equal to or greater than chat of Cs-137.
Unfortunately, published dosimecry data for Cs-134 for the infant are rather limited.
Conversion factors for the adult that use current models and metabolic data are found in
ORNL/NUREG/TM-190 (37). Johnson et al. (38) have used this same data base to compute
committed effective dose equivalent conversion factors for both infants and adults. The
mean absorbed dose per cumulated activity factor for the infant were modified by the ratio
of adult and infant organ mass (with a further correction to photon component based on
absorbed fraction) to produce the infant factors. It was stated that this procedure may
underestimate the infant dose.
The approach adopted here will be to modify the adult dose conversion factor in
ORNL/NUREG/TM-190 (37) based only on relative body weight and cumulated activity
(effective retention half-times). The dose conversion factor for cesium-13* from
ORNL/NUREG/TM-190 adult whole body is 0.068 rem/uCi ingested and the estimated
factor for the infant is then 0.118 rem/uCi ingested. This value should overestimate the
infant dose and is conservative.
Summary of Cs-13* and Cs-137 Dose Conversion Factors
Table 5. Summary of dose factors for Cs-134 and Cs-137
_____ ,
Body Mass
Uptake to whole body3
T biological (days)
T effective Cs-134 (days)
Cs-137 (days)
7,700g
1.0
20
19.5
20
70,000g
1.0
118
102
118
Dose conversion (rem / y Ci inges tion)
Cs-13* 0.118 0.068
Cs-137 ' 0.071 0.061
*For cesium-m, ORNL/NUREG/TM-190 uses uptake of 0.95.
2.1.% Strontiums Dose To Bone Marrow
The tissues ai: greatest risk in the skeleton have been identified as che active red marrow
in trabecular bone and endosteal cells near bone surfaces (generally referred to as bone
surface). Spiers and his coworkers (39,40) have developed methods ro calculate the absorbed
doses, Dm and Ds, received by red marrow and bone surfaces, respectively from beta-
emitting radlonuclides uniformly distributed throughout the volume of bone. They consider
the dose, Do, in a small, tissue-filled cavity in an infinite extent of mineral bone uniformly
contaminated with the radionuclide and give dose factors DS/DO and Dm/Do for obtaining
the absorbed doses. For both Sr-89 and Sr-90, the ratio of Ds/Dm is about 1.5. Therefore,
since the dose limit recommendations are 15 rem to bone and 5 rem to red marrow
(occupational limits), the dose to red marrow is che limiting criterion and will be used in this
report (26).
The work of Spiers and his coworkers has been used by the ICRP (27) in calculating dose
commitment factors for adults and by Papworth and Vennart (*1) for doses as a function of
age at times of ingestion. The dose commitment values from Papworth and Vennart in red
marrow per uCi of Sr-89 and Sr-90 ingested are as follows (Table 6).
10
-------
Table 6. Dose commitment values
for Sr-89 and Sr-90
Age at Ingestion
(years)
0
0.5
1
2
3
*
5
6
7
8
9
10
11
Adults3
rem per wCi
5r-S9
O.*14
0.19*
0.130
0.080
0.060
0.050
0.0*4
0.039
0.035
0.032
0.029
0.026
0.023
0.012
ingested*
5r-9Q
*.03
2.*9
1.83
1.20
0.91
0.77
0.70
0.69
0.71
0.76
0.83
0.89
0.9*
0.70
* Ages 0-11 from Papworth and Vennart
Adults from ICRP-30 Supplement to Part 1
(27).
Thus the dose conversion factors adopted in rem/uCi ingested are for Sr-89, 0.19* and
0.012, and for Sr-90, 2.*9 and 0.70, for the infant and adult, respectively. As before, die 0.5-
year infant is taken as the critical population. The values for the adult are those given In
ICRP 30 (27) which also used the work of Spiers and coworkers.
2.1.5 Other Radionuclides
Adult - The:- most authoritative reference using current data and models for dose
conversion factors per uCi ingested is mat of the ICRP 30 (27) Part 1, 1979? Part 2, 1980j
Part 3, 1981$ and the Supplements, Per gam on Press (42). ICRP 30 Parts 1, 2, and 3 (and
Supplements) provide data only for adults (occupational workers) for the radionuclides of 9*
elements.
As a further resource, ORNL/NUREG/TM-190 is suggested (37). This document
represents initial efforts by ORNL under contract to NRC to provide review and update
on internal dosimetry.
Infant, Child - Unfortunately the initial efforts to update internal dosimetry have all
been directed at the adult or occupational worker and comprehensive dosimetry using cur-
rent data for the younger age groups do not exist. Further efforts are in process or contem-
plated by the U.S. Nuclear Regulatory Commission (NRC), Medical Internal Radiation Oose
Committee, (MERD), Society of Nuclear Medicine, and NCRP, and generally will involve or
use the models developed by Oak Ridge National Laboratory (ORNL). Until such time that
new dosimetric calculations appear for the younger age group, it is suggested that Nuclear
Regulatory Commission Regulatory Guide 1.109 be used: "Calculation of Annual Doses to
Man from Routine Releases of Reactor Effluents for the Purpose of Evaluating Compliance
with 10 CFR Part 50, Appendix I," Regulatory Guide 1.109, Revision 1, Oct. 1977, U.S.
Nuclear Regulatory Commission, Washington, D.C. 20555.
11
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2.2 AGRICULTURE TRANSPORT MODELS
A review of the agricultural transport mechanism for radionuciidest which employs pa-
rameters appropriate for the U.S. experience, is contained in the Reactor Safety Study,
WASH-1400, Appendix VI (7). An analysis specific for calculating derived response levels
(concentration values) in agricultural media for emergency action that reflects the British
experience is found in a report of the Medical Research Council (43).
A more recent and comprehensive assessment of the transport mechanisms for thu forage-
cow-milk pathway is found in UCRL-51939 and will be used here (44)
2*2.1 Transport Models
According to Ng et aL, the time dependency of the concentration of a radionuclide in
the milk of a cow continuously grazing pasture contaminated by a single event can be
described by
.
1=1 XP
where CM(t) = concentration of radionuclide in milk at time t CuCi/1)
lŁ<0) * initial rate of ingestion of radionuclide by the cow (uCi/d)
Aj = coefficient of itn exponential term, which describes the secretion in mEk (liter"1)
= effective elimination rate of the i* milk component (d~l)
radiological decay constant (d~l)
biological elimination rate of i* milk component (d** l)
Xp = effective rate of removal of the nuciide from pasture (d"1), and
Xp a XR + Xw» where Xiy is removal rate for a stable element from pasture (d"1),
and
1 9 dme of milk secretion (d).
The total activity ingested by a person who drinks this milk can now be determined by
integration:
where I » race of ingestion of the radionuclide by a person (uCi/d) and
3 = rate of consumption of milk (licer/d).
The solution for the total activity ingested by man is:
" dt
12
-------
where f M = transfer coefficient; i.e., the fraction of daily intake by cow that is se-
creted per liter of miik at equilibrium (d/liter)
Ng et al. have conducted a comprehensive review of the literature relevant to the deter-
mination of transfer coefficients for both stable elements and radionuclides (44). These
data are summarized in UCRL-51939, which also include values o* the normalized co-
efficients, A|, the biological half -life T^jBi (related to %BJ) for selected elements and
values of f ^ for all stable elements. This information is then used with the radioactive half-
life to calculate values of fiu for specific radionuclides of interest Olabie B-l of Ng et al.
(44)),
An examination of the logistics of the forage-cow-milk-man pathway shows that there is
generally a delay time between the production of milk by the cow and its consumption by
the general public. Therefore, it is appropriate to introduce a factor, S, to account for
radioactive decay between production and consumption, where
S = e "** where X = the decay constant for a given radionuciide (d~ l)
and t = the delay between production and consumption (d).
Since the delay time for fresh whole milk is assumed to be 3 days only 1-131 of the
radionuclides of interest here has a sufficiently short half-life to result in a value of S
significantly smaller than one. Thus, for 1-131: -
5(1-131) = 0.772
Therefore, the total activity ingested as calculated by the above formula (Jtdt) must 6e
multiplied by 6.772 in the case of iodine-131.
2.2.2 Total Intake
The calculated values of integrated activity ingested per uCi/m 2 deposition from
Appendix B of UCRL-51939 will be accepted as the basis for deriving the response levels
equivalent to the PAG (44) . The values in Appendix B are based on these values of
parameters? . >
(1) Ic®}» initial rate of intake by cow
UAF = "utilized area factor11 (93)
UAF m 45 m 2/d
Initial Retention on Forage = 0.5 fraction
Initial Deposition = 1 pCi/m 2
thus 1^0) = 22.5 uCi/d,
(2) 3 = 1 liter/day consumption of milk, and
(3) Half-residence time on forage is 14 days.
13
-------
The UAF of *5 m 2/d assumes a forage consumption by the cow of 11.25 kg/d dry weight
or 56 kg/d wet weight based on a forage yield of 0.25 kg/m (dry weight)
The values of the total intake per unit deposition ( uCi uCi m *) for a 1 -liter per day
milk intake from Ng et al.» are given in Table 7, line 1
T«Uo 7. Derivation of reroome levedj equivalent to 1 r em OOM ccmmiinem to critioU organ
1.
2.
3.
».
S,
6.
7.
S.
I - 131 C» - 13* Cs - 137 Sr • 90
Pathway Intake factory (»2) 1.3* 3.12 3.22 ,63fi
(«e!/uCI/oi* MT i/d)
Want Adult infant Adult Infant Adult infant Adult
Dc*c conversion factor 16 1.5 .US .OftS .0?! .Ofit 2.»9 .70
_Łrcm^uCI Inns»ted)
Intake pw nm / 1 5 .0*3 .Ł7 S.3 14.7 14.1 16. » .«« 1.43
1 iHTF
(uCl Intalce per rem)
SptdJlclntrt«f««er(Bi»lx . .72* .37* 2. IS 1.72 2.23 1.77 .« .35
0.7 oc 0.55) - (uCI oer « Cl/m*
Mtiat suriKe deootltian riiw_|) .0** 1.17 3*9 S-6 6.3 9.3 .M 4.1
Tfisrr'
^vGl/irf p«r ran)
Fetkcancefttrationfacuir (se*t«xt) ' 0. lit. 0.073 0.57S 0.01%
fuCI/Jt per u Cl/m'J
Pe»k mUk coocMitr»tl
^uCl/kK tier rein)
Sr - W
.H6
Infant Adult
.19* .012
3,2 S3
.322 .233
16 329
0.01$
.2SS 3.9
S.W! LK
^Corrected for decay durtng dlrtribution (3 days factor - .772}
2.3 DIETARY INTAKE
Want less than i year old - For the purposes of these recommendations, the dietary
intake of milk is estimated to be 0.7 liters per day for a newborn infant.
Based on the average intake up to and including 1 year of age, the daily intake of milk
for an infant less than 1 year of age Is 0.7 liters (46). An additional 300 g ol food may also
be assumed to be ingested by an infant less than 1 year of age (based on intake of 6 month-
old infants - Kahn, B.
Adult - Based on U,S, Department of Agriculture Household Food Consumption Survey
196J-19S6, the average consumption for the general population is given in Table 8. The
dietary intake of milk is taken to be 0.55 liters per day for the adult.
In addition to water ingested in food and drink, an estimated 150 ml of tap water is also
ingested each day (*6) for m total daily food intake of 2.2 kg.
-------
Table 8. Average consumption for the general population
Average consumption
for the general population
Food g/day % of total diet"
Milk, cream, cheese, icecream3 567.5 27.2
Fats, oils 54.5 2.6
Flour, cereal 90.8 4.3
Bakery products 149.8 7.2
Meat 217.9 10.4
Poultry 54.5 2.6
Fish and shellfish 22.7 1.1
Eggs 54.5 2.6
Sugar, syrups, honey, molasses, etc. 72.6 3.5
Potatoes, sweet potatoes 104.4 5.0
Vegetables (excluding potatoes) fresh 145.3 7.0
Vegetables canned, frozen, dried 77.2 3.7
Vegetables juice (single strength) 9.1 0.4
Fruit, fresh 163.4 7.8
Fruit canned, frozen, dried 36.3 1.7
Fruit juice (single strength) 45.4 2.2
Other beverages
(soft drinks, coffee, alcoholic bvgs.)
Soup and gravies (mostly condensed)
Nuts and peanut butter
Total : 2088.1 99.9
^Expressed as calcium equivalent! that is, the quantity of whole fluid
milk to which dairy products are equivalent in calcium content.
(From the U.S. Department of Agriculture Household Food Consump-
tion Survey, 1965-1966)
2.4 CALCULATIONS
The calculation of the derived response levels equivalent to 1 rem dose commitment
to critical organ for die grass-cow-miik-man pathway is summarized in Table 7. An explana-
tion of Table 7 and the calculations follow:
Line 1 Pathway Intake Factor is the total intake (uCi) for a 1 liter per day milk
ingestion per 1 uCi/m2 of initial area deposition (44).
Line 2 Dose Conversion Factor is the dose commitment in rem/yCi ingested. See
section 1 for summary.
Line 3 Intake per rem is intake in uCi to yield a 1 rem organ dose.
COMPUTATION - The reciprocal of line 2.
Line 4 Specific Intake Factor is me product of the Pathway Intake Factors (line 1) and
the milk ingestion rate of 0.7 I/day infant or 0.55 I/day adult. In the case of 1-131, a
factor of 0.772 is included to adjust for 3 day's decay between production and consumption.
COMPUTATION - Line 1 x (1 or .772) x (0.7 or 0.55)
Line 5 Initial Surface Deposition is initial area deposition of a specific radionuclide in
ViCi/m* which gives a 1-rem dose commitment.
15
-------
COMPUTATION - Lin* 3 divided by Line 4
Line 6 Peak Concentration Factor is the peak maximum concentration in milk (wCi/1)
from an initial area deposition of 1 uCi/m*. Summary in Section 2.2.3 per model of
Ng et aL (44).
Line 7 Peak Milk Concentration is the maximum milk concentration ( yCi/1) that yields
a dose commitment of 1 rem from continuous ingestion of the contaminated milk supply.
COMPUTATION - Line 5 x Line 6
Line 8 Initial Grass Concentration is the activity concentration (uCl/kg) on grass
(edible forage) chat results from the Initial Surface Deposition giving a 1-rem dose
commitment.
Retention fraction on forage - 0.5
Forage yield - 1.25 kg/m2 (wet weight)
COMPUTATION - Line 5 x 0.5
1.25 kgm*
The derived response levels that correspond to the Preventive PAG (1.5 rem thyroids 0.5
rem whole body and bone marrow) and the Emergency PAG (15 rem thyroid; 5 rem whole
body and bone marrow) are given in Tables 9 and 10.
Table 9» Derived response levels for grass-cow-milk pathway equivalent
to Preventive PAG dose commitment of 1.5 rem thyroid, 0.5 whole body
or red bone marrow to infant1
Response levels for
Preventive PAG I-1312 Cs-1343 Cs-137a Sr-90 Sr-89
Initial activity
area deposition
( WCi/m2)
Forage concentration*
( uCi/kg)
Peak milk acitivity
( uCi/1)
Total Intake (uCi)
0.13
0.05
0.015
0.09
2
0.2
0.15
4
3
1.3
0.24
7
0.5
0.18
0.009
0.2
8
3
0.14
2.6
^Newborn infant includes fetus (pregnant women) as critical segment of population
for Iodine-131. For other radionuclides, "infant" refers to child less than 1 year of
age.
2From fallout, iodine-131 is the only radioiodine of significance with respect to milk
contamination beyond the first day. In case of a reactor accident, the cumulative
intake of iodine-133 via milk is about 2 percent of iodine-131, assuming equivalent
deposition.
'Intake of cesium via the meat-man pathway for adult may exceed that of the milk
pathway; therefore, such levels in milk should cause surveillance and protective ac-
tions for meat, as appropriate. If both Cs-134 and Cs-137 are equally present, as
might be expected in reactor accidents, the response levels should be reduced by a
factor of 2.
"Fresh weight.
16
-------
Table 10. Derived response levels for grass-cow-milk pathway equivalent to emergency PAG dose commitment
of 15 rem thyroid, 5 rem whole body or red bone marrow
Response levels for I-131* Cs - 134* C$ - 137*Sr-90Sr - 89
emergency PAG Infant1 Adult Infant' Adult Infant2 Adult Infant2 Adult Iniant2 Adult
Initial activity
area deposition
CpCi/m8)
Forage concentration
1.3
0.5
18
7
20
8
40
17
30
13
50
19
5
1.8
20
8
SO
30
1600
700
Peak milk activity
(iiCi/4) 0.15 2 1.5 3 2.4 4 0.09 0.4 1.4 30
Total intake (uCI) 0.9 10 40 70 70 80 2 7 26 400
'Newborn infant includes fetus (pregnant women) as critical segment of population for iodine-131.
2"Infant1* refers to child less than 1 year of age.
3From fallout, iodine-131 is the only radioiodlne of significance with respect to milk contamination beyond first day. In case
of a reactor accident, the cumulative intake of iodine-133 via milk is about 2 percent of Iodine-131 assuming equivalent de-
position.
"Fresh weight.
'intake of cesium via the meat-man pathway for adult may exceed that of the milk pathway! therefore, such levels in milk
should cause surveillance and protective actions for meat, as appropriate. If both Cs-134 and Cs-137 are equally present as
might be expected for reactor accidents, the response levels should be reduced by a factor of 2.
-------
CHAPTER 3. METHODS OF ANALYSES FOR RA0IONUCLIDE DETERMINATION
3.1 INTRODUCTION
The measurement of radtonuclldes In food can be accomplished by either laboratory
methods or field methods using portable survey instrumentation. Unfortunately, neither
method of analysis was developed expressly for the purpose of implementing protective
actions. In order to provide instrumentation guidance to the States, the Federal Radiologi-
cal Preparedness Coordinating Committee formed a Task Force on off site instrumentation.
A draft report on instrumentation analysis methods for the milk pathway is now undergoing
review by the Task Force and a second report on other food is under development. This
effort is being'fostered by past and current contracts of Nuclear Regulatory Commission
(NRC) and Federal Emergency Management Agency (FEMA) with Brookhaven National Lab-
oratory and Idaho National Engineering Laboratory.
The material and methods are given as interim guidance until these more definitive
reports are available, It should be noted that laboratory methods of Chapter 3,2, below,
were developed for environmental monitoring purposes and are more sensitive than required
for protective actions implementation. And, conversely, the field methods of Chapter 3.3
are generally inadequate for the purpose of implementing action at the Preventive PAG
level. Analysis methods should be able to measure radionuclide concentrations in food lower
by a factor of 10 than the derived levels for Preventive PAG, Thus, it may be necessary to
use a combination of laboratory and field methods in implementing and ceasing protective
actions.
3.2 DETERMINATIONS OF RADIONUCLIDE CONCENTRATIONS BY SENSITIVE
LABORATORY METHODS
Many compendia of- methods of analysis of environmental samples are available. The
EML Procedure Manual recommended is noted for its up-to-date methodologies, which
continuously undergo revision and improvement (%D« Analysis need not be limited to refer-
ence *S but laboratory analysis of food should provide limits of detection as listed below,
which are lower than required for protective action?
Limit of detection*
Radionuclide pCl/liter or kg
1-131 10
Cs-137 10
Sr-90 i
Sr-89 5
•"Concentration detectable at the 95-percent confidence level,
A source of more rapid methods of analysis of radionudides in milk, applicable to these
recommendations is described by B. Kahn et al. (*9). The methods for gamma radionuciide
analysis (applicable to I-13J and Cs-137 presented in this reference are also applicable to
pasture. The gamma scan determinations of 1-131 and Cs-137 in milk (or water) can
generally be accomplished within 2 or 3 hours. For samples measuring in the 0-100 pCI/iicer
range, the error at the 95-percent confidence level (2 sigma) is 5 to 10 pCi/liter. For
samples measuring greater than 100 pCi/liter the error is 5 to 10 percent.
18
-------
Radiostrontium procedures permit analyses of several samples simultaneously in 5 hours
of laboratory bench time, plus 1-2 weeks for ingrowth of yttrium daughters. If the laborato-
ry is set up for routine analysis of these radionuclides recovery in tracer studies is 80 ± 5
percent.
An ion exchange field method for determination of 1-131 in milk, which uses gamma
spectroscopy after sample collection, has also been described (X). The main advantage of
this method is that it permits a large number of samples to be processed in the field or
shipped and analyzed in a central laboratory..
For analysis of samples other than milk the HASL reference (48) is recomrr ended.
3.3 DETERMINATIONS OF RAOIONUCLIOE CONCENTRATIONS BY FIELD METHODS
3.3.1 Ground Contamination (Beta Radiation)
The conversion of ground survey readings to contamination levels can be accomplished
by using the following equations and factors (assuming a metal tube wall thickness (steel) of
30 mg/cm2):
1. Use a G-M survey meter calibrated to yield 3,000 counts/min per 1 mR/h of Ra y.
2. Hold the probe not more than 5 on above- the ground with the beta shield open.
3. Assure that 100 counts/min can be detected above a normal 50 to 100 counts/min
background.
4. Take readings in open terrain? that is, not in dose proximity to heavy vegetation,
cover, or buildings.
For determinations of ground deposition:
D = Rx.F
where, D = ground deposition (in yCi/m2),
R = G-M reading (in units of 102 counts/min) (background
corrected), and
F = factor given in Table 11.
For determination of concentrations in vegetation:
C = (Dxf)d
where, C = concentration (in y Ci/kg),
D = ground deposition (in y Ci/m2),
f = fraction of deposited nuclide in the vegetation, and
d a density of vegetation cover (in kg/m2).
Generally, f ranges from 0.1 to 1 and is usually taken to be 0.25 for 1-131 in the
United Kingdom, and 0.5 in the United States.
19
-------
Data of a similar nature may also be found in "Emergency Radiological Plans and Proce-
dures," in che Chapter (Item 04.3.4) on "Conversion of Survey Meters to Concentration," (51).
Table 11. Ground surface contamination levels3 of various nuclides
required co yield 100 counts/min (net) on a G-M meter (open window)
—_~~F
Nuclide : (y.Ci/tn2 per 100 counts/min)
Zr-95 + Nb-95 6
Ce-141 2
1-131, Ru- 103m, mixed Ru-Rh (100-d old)b 1
Co-60, Sr-89» Y-90, Y-91, Cs-137, Ba-140, La-140
Ce-144 + Pr-144, Ru-105 + Rh-106,
mixed radioiodines (1-h to 1-week bid),
mixed fission-products (100-d old)
0.3
"Level varies with background readings, ground roughness, and vegetation cover,
°Age refers ro time since irradiation of the fuel from which the Fission Products were
released.
3.3.2 Herbage
A field method for estimation of radionuclide contamination at the response levels
equivalent to the Emergency PAG for pasture (forage) which has been suggested by
International Atomic Energy Agency (52) is as follows?
1. Obtain enough vegecation to fill a 30 cm x 40 cm plastic bag approximately half
full. This is about one-third of a kilogram (Note: the vegetation cover should be obtained
from at least 1 m2 of ground. The vegetation should be cut at approximately 1 to 2 cm
from the ground and should not be contaminated in the process by soil).
2. Note the area represented by this quantity of material.
3. Compress the air from the bag and seal.
4. Transfer the sample to a low background area.
5. Flatten bag and lay probe of a portable G-M survey meter on the center of the bag.
6. Wrap bag around probe and note reading (window open and background corrected).
7. Calculate the contamination from the following equation:
C = R/k
where, C = vegetation concentration (in y Ci/kg),
R = G-M reading (in units of 102 councs/min) (background corrected), and
k = 102 counts/min per y Ci/kg as given in Table 12.
8. Convert y Ci/kg to u Ci/m2 on the basis of che area represented by the sample.
20
-------
9, The limiting radionuciide (i.e.» having the lowest recommended PAG relative to
its deposition on pasture) is iodine-13 L According to Table 12, this radionuclide
is detected with the lowest efficiency. Thus, if the operator assumes this
radionuclide to be exciusively present in the pasture the most conservative
estimates relative to the Emergency PAG would be reached.
Table 12. Typical G-M survey-meter readings probe
inserted in the center of a large
sample i f vegetation
k
Nuclide (10 * x counts/min per UCi/kg)
Sr-89, Sr-fO + Y-90 20
Ba-140*La-l«J 10
1-131. Cs-137 4
3.3.3 Milk
The experimental data for field determination of radtonudides in milk are limited to
detennination of iodine-131, and the details are rather sketchy. What material is available
is abstracted below.
•1. Although no data are available for field determination of radionudides other than
iodine-131 in milk, Table 13 presents experimental information obtained in water (52,53).
To the extent milk is more self-shielding than water, the following data is presented as a
guide rather than a means of analysis.
Table 13. G-M survey-meter open window readings (counts/min
per pCi/liter) (probe immersed in contaminated water)
Size of sample container
Nuclide I liteF ' 5 liters > 10" liters
Sr-gf 2000 2000 2000
Sr-90 + Y-90 2000 2000 2000
Ru-106-(.Rh-105 6000 3000 10000
1-131 500 800 1000
Cs-137 WO 600 800
Ba-lW + La- UP 1000 1500 2000
2. Method of Kearney
a. tetrumentj CDV-700 Model No. 6B with beta window dosed at all times.
b. Geometry; See Figure 1.
c. The count rate is determined by_ ear. H the counts per minute recorded bv_
ear are more than 60 to 70 cpm, then the milk should be diluted with "pure"
water so as to produce a sample having a 5096-50%, 25%-75% or other
concentration low enough to produce counts per minute somewhat less than
60 to 70 cpm.
d. Background: The experimental conditions duplicated "sky shine" from a trans-
Pacific transfer of fallout. If the exposure around the test hole was 0.75
mR/hr a couple of feet above the hole, the sky shine increased cpm recorded
21
-------
by the probe shielded within the test hole by 3 cpm. Background, on the aver-
age, was measured (in "pure" water) to be 12 to 15 cpm (in an uncontaminated
environment). Thus, total background counts (with sky shine) is on the average
around 19 cpm.
e. From Figure ,2, the net counts per minute equivalent to the response level for
the Emergency PAG applicable for milk (infant as critical segment of
population) is approximately 20.
3. Method of C. Distenfeld and 3. Klemish (55).
a. Instruments:
i. CDV 700 instrument turned to 10 X scale and calibration adjustment turned
to require the meter to indicate 2 mR/hr. (NB: Discrepencies were noted
between data from scale and pulse counting with an oscilloscope).
iL Modified CDV 700 M with factory calibration. Good agreement between
scale reading and electronic check.
b. Geometry: The basic container was a 5-gallon heavy-wall polyethylene "Jerri**
type measuring 12x9x10 inches. A 2-inch O.D. blind tube was installed to
allow the G-M probe to sample the center of the container.
c. Counts were taken inside and at the top. (external) to the container.
d. Background was determined in a water filled plastic container (15x25x20 cm)
about 7 meters from the sample vessel.
e. Net counts per minute equivalent to the response levels for the Emergency
PAG for milk are summarized in Table 14.
4. The International Atomic Energy Agency reports on a series of experiments (53).
The data are duplicated in Table 15.
5. A forthcoming report of the Federal Interagency Task Force on Off site
Emergency Instrumentation for Nuclear Incidents to be published by FEMA is
"Monitoring and Measurements of Radionuclides to Determine Dose Commitment
in the Milk Pathway." A subsequent report by the Task Force will address field
methods and monitoring strategies for other food pathways.
6. The relative sensitivity of the various techniques is summarized in Table 16.
22
-------
Woter tight
Al or plastic tub*
(1" fo 1 1/2"
atom.; 3' long)
Plastic lining
Eirthflll-6
a) 17.3 qts of
pur* waier //t
for faked, or 7//
b) Contaminated 20 «\ .
_««. W< \ — —
Figure 1. Geometry for making
measurements within a volume
of liquid.
5 gel. container
(small plastic
garbage eon)
3.3" stick In
bottom of tub*
*CDV-700. Model No. 68 covered with smalt plastic bag taped to cable
of probe to further protect against dampness.
(After K»amy ORNL-4900)
20 40 60 80 100 120 140 160 ISO 200 220 240
Net Counts Per Minute*
*Net counts per minute determined by car. Net counts per
minute = grosscounts per minute — background in pure water.
Figure 2. Net counts per minute*
23
-------
Table 14. Net counts per minute equivalent to the response
levels for the Emergency PAG for milk
Instrument
Probe Position
Approximate
net counts per minute
CDV-700
Inside Outside
CDV-700M
Inside Outside
Response level for
Emergency PAG
(Milk-Infant) 20s
(Milk-Adult) 260
110
220
2,900
100
1.300
aAt or below background cpm - precision not adequate.
Table 15. Survey-meter readings versus concentration
of 1-131 in a 40-liter milk can
Meter
used
Al-waUed
GM probe
Mica- window
GM probe
a,8,Y
scintillation
survey-meter3
Transportable
single-channel
analyzer system
yCU-131 /liter
milk
0.9
0.5
0.1
0.05
Background
0.9
0.5
0.1
0.05
Background
0.9
0,5
0.1
0.05
Background
0.10
0.05
0.01
0.005
Background
Net counts
Inside can
1,500
500
100
50
50
600
400
100
50
50
5,500
3,000
600
250
100
1,200
650
140
80
30
per minute
Outside can
300
200
50
50
50
250
100
50
50
50
3,000
1,500
300
150
100
—
-
-
-
-
Crystal is 3-mm thick" disc of "Biopiastic" scintillator sprayed with
10 mg/cm2 of ZnS. Effective area is 6.4 cm2.
24
-------
Table 16. Comparison of methodologies
cpm per uCi liter"1
Inside Outside
IAEA - 197* (52) 1,000
Kearney - ORNL (5*) 1*0
Distenfeld and Klemish - Brookhaven (55)
CDV-700 13* 56
CDV-700M 1,*50 660
IAEA - 1966 (53)
Al Wailed GM Probe 1,100 350
Mica-Window GM Probe 700 250
at 8»Y Scintillation 6,000 3,300
Survey Meter
Transportable Single 12,000
Channel Analyser
25
-------
CHAPTER*. PROTECTIVE ACTIONS
The National Advisory Committee on Radiation (56) (NACOR) made the f oilowing recom-
mendation that applies to action taken to reduce potential exposure following the accidental
release of radioactivity:
"A counter-measure, useful to public health, must fulfill a number of requirements.
First, it must be effective; that is, it must substantially reduce population exposures below
those which would prevail if the counter measure were not used. Second, it must be safe;
i.e., the health risks associated with its use must be considerably less than those of the
contaminant at the level at which the counter-measure is applied. Third, it must be
practical. The logistics of its application must be well worked out; its costs must be-
reasonable; and all legal problems associated with its use must be resolved. Next,
responsibility and authority for its application must be well identified. There must be no
indecision due to jurisdictional and misunderstandings between health and other agencies
concerned with radiation control. Finally, careful attention must be given to such
additional considerations as its impact on the public, industry, agriculture, and govern-
ment."
An action, in order to be useful must be effective, safe, and practical. An action may- be.
applied at the source in an attempt to control the release of radioactivity from the source;
or, the action may be applied at the beginning of the food chain (soil, vegetation, or cattle),
to the immediate vector prior to ingestion by man (milk or food), or to the population itself.
For the most part these recommendations suggest protective actions to milk, human and
animal foods, or soil and this chapter is limited to actions concerning these media. Further
recommendations by NACOR (56) extend the discussion of protective measures to public
health actions directly affecting the exposed population. For details of agriculture actions,
several Department of Agriculture reports are available that deal with specific actions for
crops and soil (57,58,59).
Potential actions relative to the pasture-milk-man pathway are summarized in Table 17.
For this pathway, only four countermeasures are rated as effective, safe, and practical (a
somewhat arbitrary scale of judgment was used). Of the four, one has distinctive
disadvantages. Although removal of radionuclides from milk has been shown to be practical
no facilities for doing this exist. Another, diverting fresh milk to processed milk products,
freezing and/or storage, is effective only for short-lived radionuclides. Thus, changing
dairy cattle to an alternate source of uncontarninated feed and condemnation of milk
are the only two protective actions rated good for effectiveness, safety, and practicality.
Of course the other countermeasures should also be considered, but they appear less
promising.
Actions for fruits and vegetables are presented in Table 18 (60,61,62). Note that studies
in which these products were contaminated under actual conditions with fallout (Studies
2 and 3) yielded a lower reduction in the radioactivity removed during preparation than
was the case in an investigation (Study 1) in which radionuclides were sprayed on the food.
Depending on the food, reductions between 20 and 60 percent in strontium-90 contaminations
are possible by ordinary home preparation or by food canning processes (60).
Milled grains contain only a small portion of the total radioactive contamination of
the whole grain; removal of bran from wheat and polishing of rice are effective methods of
reducing contaminating fallout (58). Todd indicated average concentration of Sr-90 (pCi/kg)
26
-------
in wheat of wheat berry (22%), wheat bran (68%), and only *.*% in flour. In rice the corres-
ponding values ares whole grain (4.9%), and milled rice (0.7%) (58).
Although these recommendations are intended for implementation within hours or days
after an emergency, long-term actions applicable to soil are shown for information purposes
only In Table 19. Alternatives to decontamination and soU management should be
considered, especially if the radioactive material is widespread, because great effort is
required for effective treatment of contaminated land.
The concept of Protective Action assumes that the actions irnpian ented will continue
for a sufficient period of tune to avoid most of the projected dose. Tie concentration of
radioactivity in a given food will decrease because of radioactive decay and weathering as a
function of time after the incident* Thus, as discussed in Chapter 5 of this report, actions
that have a positive cost-benefit ratio at the time of initial contamination or maximum
concentration may not have a positive cost-benefit ratio at later times. Therefore, depend-
ent on the particular food and food pathway, it may be appropriate to implement a series of
protective actions until the concentrations in the food have essentially reached background
levels.
As an example of the implementation of protective actions, consider the case where an
incident contaminates the pasture-cow-miik-man pathway with a projected dose of 2-3
times the Emergency PAG due to iodine-131. In such a situation these protective actions
may be considered appropriate:
1. Immediately remove cows from pasture and place them on stored feed in order to
prevent as much iodine-131 as is possible from entering the milk;
2. Condemn any milk that exceeds the Emergency PAG response at the farm or milk
plant receiving station;
3. Divert milk contaminated at levels below the Emergency PAG to milk products;
and
4. Since the supply of stored feed may be limited and the costs of this protective
action greater than diversion to milk products, the use of stored feed may be the first
action to ceasei this should not be done, however, until the concentration of 1-131 has
dropped below the Emergency PAG and preferably is approaching the Preventive PAG.
5. The diversion of fresh milk to milk products must continue until most of the
projected dose has been avoided; this action might be ceased when the cost-effectiveness
point is reached or the concentration of iodine-131 approaches the background levels.
This discussion assumes that there is an adequate supply of whole milk from noncon-
taminated sources, that there is an available manufacturing capacity to handle the diverted
milk, and that the iodine-131 is the only radionuciide involved. In an actual situation these
conditions may not be present and other factors may affect the practicality of proposed
protective actions. The agency responsible for emergency action must identify and evaluate
those factors that affect the practicality of protective action, and thus develop a response
plan (with tentative protective action) that is responsive to local conditions and capabilities.
27
-------
Table 17. Actions applicable to the pasture-milk-man pathway (compiled from references 57 and 59)
Action
Radlonuclide(s) for which protective action Is applicable
Practicality
Effectiveness Safety (effort required)
Applicable to cattle
Provide alternate source of
uncontaminated animal feed
Add stable Iodine to cattle ration
Add stable calcium to cattle ration
Add binders to cattle ration
Substitute sources of uncontaminated water
Applicable to milk
Condemnation of milk
Divert fresh milk to processed milk products
Process fresh - store
Process fresh - store
Remove radionuclides from milk
I$1I, "Sr, "Sr, l"Cs
in,
"Sr, "Sr
"V
'Cs, "Sr,
'Cs, "Sr,
Sr
"
Sr
"'I. "Sr, "Sr, '"C,
'"I. "Sr
"
ll7
Sr, "'Sr
in,
"'I, "Sr, "Sr, "Cs
Good
Marginal" Some hazard
Marginal Some hazard
Marginal Questionable
Marginal Questionable
Good
Good
Good
Good
|»(+); 90Keffective
Marginal; less than 90%effective
^Depends on availability
dSomewhat dependent on volume
eNo processing plant presently available
-------
Table 18. Percent reduction in radioactive contamination of fruits and vegetables by processing
N)
VO
Study 1(60)
Normal food preparation for freezing, canning or dehydration Study 2 (Ł1) Study 3 (62)
External Contamination* Internal Contamination3 Canning Home preparation
Spinach
Snapbeans
Carrots
Tomatoes
Broccoli
Peaches
Onions
Potatoes
Cabbage
Green beans
92 95
.
-
. -• •
94 92
«" 100 "» 100
.
- -
-
64
. , ' ' - ''••
-
65
72
-100
-
-
_ .
-
88 22
62
19
21
89
-vi 100 : 50
'
-
_ _ -
-
—
-
19
28
_
-
37
24
5J
36
Contamination on surface is referred to as external contamination. Internal contamination is contamination of fleshy portion
of product from surface deposition of radionuclide.
-------
Table 19. Actions applicable to soli (compiled from references 57 and 59)
Action
Radionuclide(s) for which protective action is applicable
Practicality
Effectiveness8 Safety (effort required)1*
Applicable to soil
Soil management—minimum tillage:
deep plowing with root inhibition
irrigation & leaching
liming & fertilizing
Removing contaminated surface crops
Poor to fair
Good to fair
Poor
Poor to fair
Most poor
Not applicable
it
Good
Poor
Good
Good
Poor to fair
Removal of soil surface contamination:
warm weather with vegetation cover 98Sr
cold weather no cover 8eSr
Good to f ah- "
Good to poor «
Poor
Good to poor
aRating for reducing strontium -90
Good - 95% reduction
Fair - 75-95% reduction
Poor - 75% reduction
"Rating for effort required
Good- not significantly more than normal field practice
Fair - extra equipment or labor required
Poor - very great requirement of equipment, materials, and labor
-------
CHAPTER 5. COST CONSIDERATIONS
5.1 COST/BENEFIT ANALYSIS
5.1.1 Introduction
The general expectation is drat protective action taken in the event of a nuclear
incident will result in a net societal benefit considering the cost of the action and the
corresponding avoided dose. These cost assessments, including cost/benefit analysis, have
not been used co set the numerical value of the PAG's but rather to evaluate the feasibility
of specific protective actions.
At least two basically different approaches can be used to assess the cost/benefit ratio
of protective actions for the milk pathway. One approach would be to assume a protective
action scenario (maximum milk concentration and length of time of protective action) and
to calculate the total cost of the action and the benefit because of the avoided dose. The
ratio of the cost/benefit can then be used to scale the maximum milk concentration to that
concentration that yields equal costs and benefits. The problem with this approach is that
positive net benefits when milk concentration of radioactivity is high are used to offset
the negative net benefits during the later times of action.
This deficiency leads to the second approach of calculating the milk concentration on a
per liter basis where the cost of the protective action equals the benefit because of the
dose avoided. This approach will be used here since it gives a clearer picture of the
identified costs and benefits. The specific concentration at which costs equals benefits
should not however be viewed as the appropriate level for taking protective action. The
philosophy of protective action is to cake action to avoid most of the projected doses.
Further, the simple analysis considered here treats only the direct cost of protective
actions and ignores die administrative costs of starting, monitoring, and ceasing action,
and other related social and economic impacts.
Although the PAG recommendations provide that protective actions be taken on the
basis of projected dose to the infant, cost/benefit analysis must consider the cost impact
on the milk supply and the benefit on a whole population basis. Accordingly the benefit
realized from avoiding the dose associated with a given level of milk contamination
C (uCi/1) must be summed over the age groups having different Intakes (0 and Oose
Factors (DF) and is:
Benef i t = C (u Ci/1) x Value ($/rem) 2Ii(l/d).DFi(rem/ ji Ci).
The total cost of the protective actions, which must also be summed over all the age intake
groups is:
Cost = PA COST x ZIi
Costs are in 1980 - 1981 dollars. These equations can then be solved for the concentration
(C) at which cost = benefit givings
C (C=B) . PA COST m
Value (S/rem) Z(Ii • DF
31
-------
5.1.2 Benefit of Avoided Dose
In situations in which there has been an uncontrolled release of radioactivity to the
environment, both the heaidi savings and cost of a protective action can be expressed in
terms of dollar values. This does not exclude the probability that undesirable features will
result from an action that is difficult to evaluate in economic terms.
A previous cost-benefit analysis described the radioactive concentration of iodine-131 in
milk at which IE would be justifiable to initiate condemnation of milk (63). Following is a
summary of the moneta-y benefit of radiation dose avoided using the approach suggested,
with changes because of increased costs over time and new data on the relative incidence of
various tumors.
The International Commission on Radiological Protection, (64) has endorsed the principle
of expressing the detriment from radiation in monetary terms in order to facilitate
simplified analysis of costs and benefits. This permits a direct comparison between the
societal advantage gained in a reduction of the radiation dose and the cost of achieving this
reduction. Cost-benefit analysis is the evaluation process by which one can determine the
level at which, or above which, it would be justifiable to initiate the protective action
because the health savings equaled or exceeded, the economic costs of the protective
action. Certain factors, such as loss of public confidence in a food supply, are not
considered; nor are economic factors because of hoarding and a shortage of supply
considered. A similar treatment of die problem with almost the same result has
been published (65). This type of exercise is useful prior to taking an action as one, and
only one, of a series of inputs into decisionmaking.
The costs, and hence health savings to society, of 1 person-rem of whole-body dose (the
product of a dose of 1 rem to the whole body and 1 person) has been estimated by various
authors to be between $10 and $250 (66). The Nuclear Regulatory Commission (NRC) value
for a cost-benefit analysis for augmented equipment for light-water reactors to reduce
population dose, sets radiation costs at $1000 per person-rem (67).
Based on medical expenses In 1970, the total future cost of the consequences of all
genetic damage of 1 person-rem (whole-body) was estimated by the BEDR. Committee (2) to
be between $12 and $120. These costs are in good agreement with estimates made by
Arthur D. Little, Inc., for the Environmental Protection Agency, which calculated that
in terms of 1973 dollars, 1 person-rem of radiation yielded a tangible cost of between $5 and
$181 due to excess genetic disorders. A tangible cost of between $7 and $24 per person-rem
was estimated to be the result of excess cancer in the same report. Therefore, the total
health cost of a person-rem from these studies is between $12 and $205 (68).
Assuming that $200 is a reasonable estimate for the overall somatic health cost to socie-
ty per person-rem whole body, the proportionate cost for individual organ doses must then
be derived. For the purposes of assessing health cost, it is appropriate to use the relative
incidence of cancer estimated to result from organ doses vs. whole body doses. From BEIR-
in (3) (Table Y-14 and V-17, and using an average of the male and female incidence) the
thyroid contributes 20 percent of cancer and leukemia (red bone marrow doses) 11 percent
of the total cancer incidence. Hence, the monetary costs per rem of radiation dose avoided
are: to thyroid $40; and to red bone marrow $22.
5.1.3 Protective Action Costs
The direct cost of protective action will be assessed for (1) cost of stored feed, (2)
condemnation at the farm (farm value), and (3) condemnation at the processing plant (retail
value).
1. Cost of stored feed. For the participating herds (May 1, 1978 - April 30, 1979)
the Dairy Herd Improvement Letter (69) reports a consumption of 12,600 Ibs. of succulent
32
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forage and 3,000 Ibs. of dry forage, with a corresponding annual milk production of 14,129
Ibs. T6200 liters). (The cows also consumed 5,300 Ibs. of concentrates, which are not of
concern here.) Taking 3 Ibs. of succulent forage (silage) as equivalent to 1 Ib. of hay, the
annual hay equivalent consumption is 7,200 Ibs (70). Thus, 1.16 lbs« of hay equivalent is
consumed per liter of milk production. The 1980 average price received by farmers for all
baled hay was $67.10 per ton or $0.0335 par Ib. (71). The Protective Action (PA) cost of
buying baled hay to replace pasture as the sole forage source is then $0.039 per liter.
2. Milk-farm value. The average pt 'ce received by farmers for fluid-eligible milk,
sold to plants and dealers in 1980, was $13.11 per hundred weight (monthly range $12.70 to
$14.20) (71). The lower prices are received during the pasture season of April through
August. For 44 liters per hundred weight, the farmer value of mEk is $0.30 per liter.
3. Milk-retail value. Since it may be necessary to take protective action at some
stage in the milk processing and distribution system it is appropriate to consider the retail
value of milk. If condemnation of milk is taken at the receiving station or processing plant
there will be additional costs above farm value associated with disposal. It is felt that
retail price should represent an appropriate value. The average city retail price of fortified
fresh whole milk sold in stores, January through October 1980 was $1.037 per 1/2 gallon
(72). The monthly price increased from $1.015 in January to $1.067 in October, apparently
because of inflation. Based on the average price the value of $0.56 per liter will be used.
5.1.4 Population Milk Intake and Dose
Table 20 summarizes the milk intake by population age groups and gives values of the
age group intake factor iHl/d). The total intake by a population of 1000 is 281 1/d or an
average individual daily intake of 0.28 1. The intake factor (E) is used with the dose factor
OPi listed in Table 21 to calculate the dose factor summed over the whole population
weighted by age per yCi/1 of milk contamination.
5.1.5 Milk Concentration For Cost « Benefit
The above results are then used to calcultate the milk concentration at which the
Protective Action (PA) costs equals the benefit from the dose avoided. The results are
presented in Table 22. The cost = benefit concentration for use of stored feed in place of
contaminated pasture is about 0.2 to 0.3 of the Preventive PAG for strontium and 0.01 to
0.02 for iodine and cesium. For condemnation, the cost = benefit concentrations based on
farm value of milk have ratios of the Emergency PAG similar to those above. The cost =
benefit concentrations based on retail value of milk are about a factor of 2 greater than
those based on the milk's farm value. The fact that the cost = benefit concentrations are a
significant percent of the PAG for strontium results largely because the value of the person-
rem dose to red bone marrow is one-ninth that of whole-body doses while the PAG's are set
at equal doses consistent with current regulations. Further the controlling PAG's are for
the infant, while the cost/benefit reflects population averaged benefits.
Table 20. Population milk intake
Age group
In utero
0 <1
1 - 10
11 - 20
>20
Persons per
1000 popu- Milk intake*
lation (1/d)
11
14
146
196
633
En
.4
.775
.470
.360
.200
Intake (1) by
age group
(1/d)
4.4
10.9
68.6
70.6
126.7
281.2
a!CRP, 1974
33
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Table 21. Population dose factors
Sr-89
UxDFi
DFi rem • 1.
Age group rem/uCi uCi d
In utero .*!* 1.82
0 < 1 .19* 2.12
1 - 10 .0565 3.88
11 - 20 .0175 1.2*
>20 .012 1.52
ZliDFi 10.58
Sr-90
li x DFi
DFi rem • 1,
rem/uCi wCl d
*.03 17.7
2.*9 27.2
.929 63.8
.82 57.9
.70 88.7
255.3
Reference for
DFi values3
0 yr old
0.5 yr-old
Average
Av 11 yr& adult
Adult
^ee Chapter 2.
Cs-13*
DFi rem • 1.
Age group rem/uCi uCi d
In utero .068 .3
0 < 1 .118 1.29
1 - 10 .093 6.39
11 - 20 .093 6.57
>20 .068 8.51
ZHDFI 23.06
Cs-137
UxDFi
DFi rem * I
rem/uCi uCi d
.061 .27
.071 .77
.066 *.53
.066 *.66
.061 7.73
17.966
Reference for
DFi values3
Adultb
Infant
Av. infant
& adult
H
Adult
?See Chapter 2.
"No credit taken for reduced biological half-life in pregnant women.
, 1-131
UxDFi
DFi rem • 1.
Age group rem/uCi uCi d
In utero .8 35
0 < 1 16 17*
1 - 10 5.7 391
11 - 20 2.1 1*8
>20 1.5 190
m DFi 938
Reference for
DFi valuesa
Max. estimate
Newborn
Average from
smooth curve
15 yr old
Adult
aSee Chapter 2.
-------
Table 22. Milk concentration at which cost = benefit
(Population basis - value of ZlixDFi for 1000 persons)
Sr-89 5r-90 1-131 Cs-134 Cs-137
m x DPI
rem 1
uCi'd"
10.58 255 938 23.1 17.96
Value ($/rem) 22 22 40 200 200
PA cost CONG. (Cost = Benefit) (yd/1)
Stored Feed $0.039 .0*7 .002 .0003 .0025 .003
Farm Milk 0.30 .36 .015 .0023 .018 .025
Retail Milk 0.56 .68 .028 .0042 .034 .044
Peak CONG. (uCl/1)
Preventive PAG
Emergency PAG infant
Emertency PAG adult
.14
1.4
30
.009
.09
.4
.015
.15
2.0
.15
1.5
3.0
.24
2.4
4..0
5.2 ECONOMIC IMPACT
The Emergency Planning Zone (EPZ) for the ingestion pathway has been sec ac 50 miles
(73). The area impacted that requires protective action is the major factor influencing cost.
Assessment of the economic impact will be considered for the case of contamination of the
milk pathway in one 22.5° Sector out to a distance of 50 miles. Table 23 gives data on the
annual sales of whole milk and total area of leading dairy States and selected States. The
annual milk sales In Wisconsin of 3.52 x 10s Ibs. per sq. mile exceeds that of any other
S tate and will be used to assess the economic impact. There may, of course, be individual
counties and areas surrounding nuclear power plants where milk production exceeds the
Wisconsin State average. The Wisconsin average should, however, represent a maximum for
most areas of the United States.
Table 23. Milk production of selected States
(Statistical Abstract of the U.S., 1978)
State
WI
YT
NY
PA
IA
CT
MN
OH
MI
CA
MA
NJ
Whole milk sold
(109 IDS/ year)
20.5
2.06
9.92
7.37
4.07
.595
9.27
4.43
4.63
11.53
0.55
0.52
Total area
(mi2)
56,154
9,609
49,576
45,333
56,290
5,009
84,068
41,222
58,216
158,693
8,257
7,836
Milk per unit area
10s lbs/mi2
3.52
2.14
2.00
1.64
1.38
1.19
1.10
1.08
0.80
0.73
0.67
0.66
Another important factor in assessing the economic impact of protective actions in the
milk pathway is the length of time that such actions will be necessary. During most of the
year in northern parts of the U.S., cattle will already be on stored feed and there will be no
35
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additional costs for the stored feed protective action. For other situations and the Emer-
gency PAG, the time over which protective actions will be necessary is a function of a
number of parameters unique to each site and the causative accident. Thus, what are
intended as conservative assumptions will be selected. The time behavior of 1-131 on
pasture grass is controlled by the 8-day radioactive half-life and the 14-day weathering haif-
life (yielding an effective half-life of about 5 days). Milk which contains 1-131 at the
Emergency PAG of 0.15 uCi/1 will be reduced to the cost = benefit concentration (farm
value) of 0.0023 uCi/1 about 30 days later. Obviously in most cases of an atmospheric
release, those areas closer to the release point will have higher levels of contamination and
longer times of protective action. The NEC and EPA in the Planning Basis Report NUREG-
0396 (NRO, 1978) assume that radiation doses from the airborne plu.ne decrease according
to the r" 1>S factor. Use of this factor for contamination of pasture results in milk
concentrations at 2 miles that are about 100 times that at 50 miles. For an effective half-
life of 5 days this would require an additional 30-35 days of protective action at 2 miles
over that at 50 miles to yield the same milk levels upon ceasing action. Although these
models cannot be assumed to be rigorously accurate in a specific accident situation, they do
indicate that action might be required for 1 or 2 months.
NUREG-0396 notes that the dose from milk pathway is of the order of 300 times the
thyroid dose from inhalation (74). Under this assumption (and above models), the food PAG's
would be exceeded at hundreds of miles if protective action because of inhalation were
required at 10 miles. It should be noted that the meteorological models that are empirically
derived are not likely to be valid for such long distances. Further changes in wind direction
and meteorological dispersion conditions may reduce the levels of pasture contamination
and the downwind distance. For assessing ecomomic impact, contamination of a 22.5°
Sector out to a distance of 50 miles will be arbitrarily assumed, even though actual
contamination patterns are not likely to be similar.
Under these assumptions we then haves
Area (Circle - 50 mile radius) - 7850 mi2
Area (22.5° Sector - 50 mile) - 491 mi2
Milk Production - 3.52 x 10s lbs/mi2 per year - 2.93 x 10* lbs/mi2 per month
Production (22.5°/50 mi Sector) - 1.44 x 10 7 lbs./month
Cost of Stored Feed - $0.017 per Ib. milk
Cost Impact (22.5*/5Q mile Sector) - $2.46 x 10s per month
Thus, the direct cost of placing cows on stored feed within a 22.5° Sector out to 50
miles based on farm value, would be about $0.25 million per month; The cost would be zero
during that portion of the year and in geographical areas where cattle are already on stored
feed. While such protective actions might be required for periods up to 2 months at areas
near the accident site, such would not be the case at the greater distances which involve the
major portion of the area. Condemnation of milk is the protective action of last resort for
areas of very high contamination. As noted above, the farm value of milk is $0.30 per liter.
Thus, the condemnation of milk at the Emergency PAG for a 22.5°/50 mile sector would
have a cost of about $2 million for a month of protective action. Where 1-131 is the only
significant contaminant, whole milk can be diverted to manufactured products, such as
powdered milk, which can be stored to allow disappearance of the radioactivity. We do not
have cost figures for this action.
It is of interest to compare the arbitrary assumptions on land area used above to the
contamination resulting from the Windscaie accident. (NB: This was not a power reactor of
the type presently used in the United States). According to Booker, the Windscaie accident
resulted in milk values exceeding 0.015 yCi/1 at about 200 kilometers or 125 miles
36
-------
-------
Figure 4 is a graph of the dose commitment for a design basis accident and a PWR 7
assuming protective action is initiated at specific interdiction levels. The dose commit-
ments are accrued via external as well as internal exposure (inhalation and ingestion).
Therefore, they do not exactly fit the situation described in the PAG's under consideration.
The dose commitment rises rapidly when the interdiction criteria are between 0.5 and 20
rem. The increase in dose commitment for a design basis accident is less rapid than for a
PWR 7. Hence, at or above an interdiction criteria of 20 rem, savings in radiation dose are
minimal compared to the savings accrued below 10 rem.
10* r-
10*
LU
8
10*
9 mm?
j_
J_
10 -20 30 40 50
INTERDICTION CRITERIA (nmj-tfryoid)
Figure 4. Dose commitment model accident.
5.* SUMMARY AND CONCLUSION
The milk concentration at which the population benefits (from dose avoided) equals the
direct costs of stored feed is equivalent to about one-third of the Preventive PAG for stron-
tium and to one-fiftieth or less for iodine-131 and cesium. If condemnation is based on
retail milk value, then the respective concentrations are about one-half and one-fiftieth of
the Emergency PAG. Unless the indirect costs of implementing protective actions are
significantly greater than the direct costs, it appears feasible to take protective actions at
the respective PAG level and to continue such action to avoid about 90 percent of the
projected dose for iodine and cesium. In the case of strontium contamination of milk, such
action is only cost beneficial until the concentration is about 30 percent of the PAG
response level.
Estimated costs of taking protective action within the Emergency Planning Zone (EPZ)
for a 22.5° Sector to 50 miles (about 500 mi2) is $2 million per month for condemnation
(farm milk value) and $0.26 million per month for use of stored feed. In the case of
38
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atmospheric dispersed contamination, protective action may have to continue for 2 months
near the site.
The recommended approach is to place ail cows on stored feed to prevent the
contamination oi milk at significant levels, to divert iodine contaminated milk to
manufactured products that have a long shelf life to allow radioactive decay, and only
consider condemnation of milk exceeding the Emergency PAG. It appears that doses to the
public can be limited to less than 10 percent of the Preventive PAG (or less then 0.15 rem
thyroid) by actions having direct costs of a few milion dollars for a significant accident.
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72. Bureau of Labor Statistics, US Department of Labor. Washington, DC 20212.
73. U.S. Nuclear Regulatory Commission. Criteriafor Preparation andEvaluacion of Radio-
logical Emergency Response Plans and Preparedness in Support of Nuclear Power
Planes. NUREG-0654/FEMA-REP-l. USNRC, Washington, DC 20555 (November
1980).
74. U.S. Nuclear Regulatory Commission. Planning Basis for the Development of State
and Local Government Radiological Emergency Response Plans in Support of Light
Water Nuclear Power Plants. NUREG-0396/EPA 520/1-78-016. USNRC, Washington,
DC 20555 (December 1978).
75. Booker, D.V. Physical Measurements of Activity in Samples from Windscale. AERE
HP/R2607. United Kingdom Atomic Energy Authority, Atomic Energy Research
Establishment, Harwell, Berkshire (1958).
-------
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CHAPTEB7
Implementing the Protective Action Guides for
the Intermediate Phase:
Exposure to Deposited Materials
7.1 Introduction
This chapter provides guidance for
implementing the PAGs set forth in
Chapter 4. It is for use by State and
local officials in developing their
radiological emergency response plans
to protect the public from exposure to
radiation from deposited radioactive
materials. Due to the wide variety in
types of nuclear incidents and
radionuclide releases that could occur,
it is not practical to provide
implementing guidance for all
situations. The guidance in this
chapter applies primarily to
radionuclides that would be involved in
incidents at nuclear power plants. It
may be useful for radionuclides from
incidents at other types of nuclear
facilities or from incidents not
involving fixed facilities (e.g.,
transportation accidents).However,
specific implementation procedures for
incidents other than those at nuclear
power plants should be developed by
planners on a case-by-case basis.
Contrary to the situation during
the early phase of a nuclear incident,
when decisions usually must be made
and implemented quickly by State and
local officials before Federal assistance
is available, many decisions and
actions during the intermediate phase
can be delayed until Federal resources
are present, as described in the Federal
Radiological Monitoring and
Assessment Plan (FE-85). Because of
the reduced level of urgency for
immediate implementation of these
protective actions, somewhat less detail
may be needed in State radiological
emergency response plans than is
required for the early phase.
At the time of decisions on
relocation and early decontamination,
sheltering and evacuation should have
already been completed to protect the
public from exposure to the airborne
plume and from high exposure rates
from deposited materials. These
protective actions may have been
implemented prior to verification of the
path of the plume and therefore some
persons may have been unnecessarily
evacuated from areas where actual
doses are much lower than were
projected. Others who were in the
path of the plume may have been
sheltered or not protected at all.
During the intermediate phase of the
response, persons must be relocated
from areas where the projected dose
exceeds the PAG for relocation, and
other actions taken to reduce doses to
persons who are not relocated from
contaminated areas. Persons
7-1
-------
evacuated from areas outside the
relocation zone may return.
7.1.1 Protective Actions
The main protective actions for
reducing exposure of the public to
deposited radioactivity are relocation,
decontami- nation, shielding, time
limits on exposure, and control of the
spread of surface contamination.
Relocation is the most effective, and,
usually, the most costly and disruptive.
It is therefore only applied when the
dose is sufficiently high to warrant it.
The others are generally applied to
reduce exposure of persons who are not
relocated, or who return from
evacuation status to areas that
received lower levels of deposited
radioactivity. This chapter provides
guidance for translating radiological
conditions in the environment to
projected dose, to provide the basis for
decisions on the appropriate protective
actions.
7.1.2 Areas Involved
Figure 7-1 provides a generalized
example of the different areas and
population groups to be dealt with.
The path of the plume is assumed to be
represented by area 1. In reality,
variations in meteorological conditions
would almost certainly produce a more
complicated shape, but the same
principles would apply.
Because of plant conditions and
other considerations prior to or after
the release, persons will already have
been evacuated from area 2 and
sheltered in area 3. Persons who have
been evacuated from or sheltered in
areas 2 and 3, respectively, as
precautionary actions for protection
from the plume, but whose homes are
outside the plume deposition area (area
1), may return to their homes as soon
as environmental monitoring verifies
the boundary of the area that received
deposition (area 1).
Area 4 is designated a restricted
zone and is defined as the area where
projected doses are equal to or greater
than the relocation PAG. Persons
residing just outside the boundary of
the restricted zone may receive a dose
near the PAG for relocation if
decontamination or other dose
reduction efforts are not implemented.
Area 1, with the exception of the
restricted zone, represents the area of
contamination that may continue to be
occupied by the general public.
Nevertheless, there will be
contamination levels in this area that
will require continued monitoring and
dose reduction efforts other than
relocation.
The relative positions of the
boundaries shown in Figure 7-1 depend
on areas evacuated and sheltered, and
the radiological characteristics of the
release. For example, area 4 (the
restricted zone) could fall entirely
inside area 2 (area evacuated), so that
the only persons to be relocated would
be those residing in area 4 who were
either missed in the evacuation process
or who, because of the high risk for
their evacuation, had remained
sheltered during plume passage.
7-2
-------
CO
ARBITRARY SCALE
LEGEND
L| 1. PLUME DEPOSITION AREA.
-J
PLUME TRAVEL
DIRECTION
2. AREA FROM WHICH POPULATION IS EVACUATED.
3. AREA IN WHICH POPULATION IS SHELTERED,
4. AREA FROM WHICH POPULATION IS RELOCATED (RESTRICTED ZONE).
FIGURE 7-1. RESPONSE AREAS.
-------
At the time the restricted zone is
established, a temporary buffer zone
(not shown in Figure 7-1) may be
needed outside portions of the
restricted zone in which occupants will
not be allowed to return until
monitoring confirms the stability of
deposited contamination. Such zones
would be near highly contaminated
areas in the restricted zone where
deposited radiomielides might be
resuspended and then redeposited
outside the restricted zone. This could
be especially important at locations
close to the incident site where the
radioactivity levels are high and the
restricted zone may be narrow. The
extent of the buffer zone will depend on
local conditions. Similarly, a buffer
zone encompassing the most highly
contaminated areas in which persons
are allowed to reside may be needed.
This area should be monitored
routinely to assure acceptability for
continued occupancy.
7.1.3 Sequence of Events
Following passage of the airborne
plume, several tasks, as shown in
Figure 7-2, must be accomplished
simultaneously to provide for timely
protection of the public. The decisions
on the early task of relocating persons
from high exposure rate areas must be
based on exposure rate measurements
and dose analyses. It is expected that
monitoring and dose assessment will be
an on-going process, with priority given
to the areas with the highest exposure
rate. The general sequence of events is
itemized below, but the time frames
will overlap, as demonstrated in Figure
7-2.
1. Based on environmental data,
determine the areas where the
projected one-year dose will exceed 2
rem and relocate persons from those
areas, with priority given persons in
the highest exposure rate areas.
2. Allow persons who were evacuated
to return immediately to their
residences if they are in areas where
field gamma measurements indicate
that exposure rates are near normal
background levels (not in excess of
twice the normal background in the
area before the incident). If, however,
areas of high deposition are found to be
near areas with low deposition such
that resuspended activity could drift
into the occupied areas, a buffer zone
should be established to restrict
occupancy until the situation is
analyzed and dose projections are
confirmed.
3. Determine the location of the
isodose line corresponding to the
relocation PAG, establish the boundary
of the restricted zone, and relocate any
persons who still reside within the
zone. Also, convert any evacuees who
reside within the restricted zone to
relocation status. Evacuated persons
whose residence is in the area between
the boundary of the plume deposition
and the boundary to the restricted zone
may return gradually as confidence is
gained regarding the projected dose in
the area.
4, Evaluate the dose reduction
effectiveness of simple decontamination
7-4
-------
en
DC
3
O
U
O
z
Ul
9
o
o
PERIOD OF
RELEASE,
DISPERSION,
DEPOSITION,
SHELTERING,
EVACUATION,
AND ACCESS
CONTROL
(NO TIME SCALE)
I | | HIIII—I I I HUH I I I IIHIt 1 I I I Mill
lu
5
O
O
z
o
CONDUCT AERIAL AND GROUND SURVEYS. DRAW ISODOSE RATE LINES.
IDENTIFY HIGH DOSE RATE AREAS. CHARACTERIZE CONTAMINATION.
RELOCATE POPULATION FROM HIGH DOSE RATE AREAS.
ALLOW IMMEDIATE RETURN OF EVACUEES TO NONCONTAMINATED AREAS.
ESTABLISH RESTRICTED ZONE BOUNDARY AND CONTROLS.
RELOCATE REMAINING POPULATION FROM WITHIN RESTRICTED ZONE.
GRADUALLY RETURN EVACUEES UP TO RESTRICTED ZONE BOUNDARY.
CONDUCT 0-CON AND SHIELDING EVALUATIONS AND ESTABLISH PROCEDURES
FOR REDUCING EXPOSURE OF PERSONS WHO ARE NOT RELOCATED.
PERFORM DETAILED ENVIRONMENTAL MONITORING.
PROJECT DOSE BASED ON DATA.
DECONTAMINATE ESSENTIAL FACILITIES AND THEIR ACCESS ROUTES.
RETRIEVE VALUABLE AND ESSENTIAL RECORDS AND POSSESSIONS.
REESTABLISH OPERATION OF VITAL SERVICES.
BEGIN RECOVERY ACTIVITIES.
CONTINUE RECOVERY.
MONITOR AND APPLY
ALARA IN OCCUPIED
CONTAMINATED AREAS.
Hi.
0.1
1.0 10 100
TIME AFTER DEPOSITION (DAYS)
1,000
FIGURE 7-2. POTENTIAL TIME FRAME OF RESPONSE TO A NUCLEAR INCIDENT.
-------
techniques and of sheltering due to
partial occupancy of residences and
workplaces. Results of these
evaluations may influence
recommendations for reducing exposure
rates for persons who are not relocated
from areas near, but outside, the
restricted zone.
5. Establish a mechanism for
controlling access to and egress from
the restricted zone. Typically this
would be accomplished through control
points at roadway accesses to the
restricted zone.
6. Establish monitoring and
decontamination stations to support
control of the restricted zone.
7. Implement simple decontamination
techniques in contaminated areas
outside the restricted zone, with
priorities for areas with higher
exposure rates and for residences of
pregnant women.
8. Collect data needed to establish
long-term radiation protection criteria
for recovery and data to determine the
effectiveness of various
decontamination or other recovery
techniques.
9. Begin operations to recover
contaminated property in the restricted
zone.
7.2 Establishment of Isodose-rate
Lines
As soon as Federal or other
assistance is available for aerial and
ground monitoring, a concentrated
effort should begin to establish
isodose-rate lines on maps and the
identification of boundaries to the
restricted zone. Planning for this effort
should include the development of
standard maps that can be used by all
of the involved monitoring and dose
assessment organizations to record
monitoring data.
Aerial monitoring (e.g., the
Department of Energy Aerial
Monitoring Service) can be used to
collect data for establishing general
patterns of radiation exposure rates
from deposited radioactive material.
These data, after translation to
readings at 1 meter above ground, may
form the primary basis for the
development of isodose lines out to a
distance where aerial monitoring shows
no radiation above twice natural
background levels. Air sample
measurements will also be needed to
verify the contribution to dose from
inhalation of resuspended materials.
Gamma exposure rates measured
at 1 meter will no doubt vary as a
function of the location of the
measurement within a very small area.
This could be caused by different
deposition rates for different types of
surfaces (e.g., smooth surfaces versus
heavy vegetation). Rinsing or
precipitation could also reduce levels in
some areas and raise levels in others
where runoff settles. In general, where
exposure rates vary within designated
areas, the higher values should be used
for dose projection for persons within
these areas unless judgment can be
7-6
-------
used to estimate an appropriate
average exposure rate.
Measurements made at 1 meter to
project whole body dose from gamma
radiation should be made with
instruments of the "closed window"
type so as to avoid the detection of beta
radiation. Although beta exposure will
contribute to skin dose, its contribution
to the overall risk of health effects from
the radionuclides expected to be
associated with reactor incidents
should not be controlling in comparison
to the whole body gamma dose (AR-89),
Special beta dose analyses may be
appropriate when time permits to
determine its contribution to skin dose.
Since beta dose rate measurements
require sophisticated equipment that is
generally not available for field use,
beta dose to the skin should be limited
based on measured concentrations of
radionuclides per unit area.
7.3 Dose Projection
The primary dose of interest for
reactor incidents is the sum of the
effective gamma dose equivalent from
external exposure and the committed
effective dose equivalent from
inhalation. The exposure periods of
interest are first year, second year, and
up to 50 years after the incident.
Calculation of the projected
gamma dose from measurements will
require knowledge of the principal
radionuclides contributing to exposure
and their relative abundances.
Information on these radiological
characteristics can be compiled either
through the use of portable gamma
spectrometers or by radionuclide
analysis of environmental samples.
Several measurement locations may be
required to determine whether any
selective radionuclide deposition
occurred as a function of weather,
surface type, distance from the point of
release, or other factors. As part of the
Federal Radio- logical Monitoring and
Assessment Plan (FE-85), the U. S.
Department of Energy and the U. S.
Jkivironmental Protection Agency have
equipment and procedures to assist
State officials in performing
environmental measurements,
including determination of the
radiological characteristics of deposited
materials.
The gamma exposure rate may
decrease rapidly if deposited material
includes a significant fraction of
short-lived radionuclides. Therefore,
the relationship between instantaneous
exposure rate and projected first- and
second-year annual or the 50-year
doses will change as a function of time,
and these relationships must be
established for the particular mix of
deposited radioactive materials present
at the time of the gamma exposure rate
measurement.
For incidents involving releases
from nuclear power plants, gamma
radiation from deposited radioactive
materials is expected to be the
principal exposure pathway, as noted
above. Other pathways should also be
evaluated, and their contributions
considered, if significant. These may
include inhalation of resuspended
material and beta dose to the skin.
7-7
-------
Exposure from ingestion of food and
water is normally limited
independently of decisions for
relocation and decontamination (see
Chapters 3 and 6), In rare instances,
however, where withdrawal of food
and/or water from use would, in itself,
create a health risk, relocation may be
an appropriate protective action for
protection from exposure via ingestion.
In this case, the committed effective
dose equivalent from ingestion should
be added to the projected dose from
other exposure pathways for decisions
on relocation.
The following sections provide
methods for evaluating the projected
dose from whole body external
exposure and from inhalation of
resuspended particulate material,
based on environmental information.
7,3.1 Projected External Gamma Dose
Projected whole body external
gamma doses at 1 meter height at
particular locations during the first
year, second year, and over the 50-year
period after the incident are the
parameters of interest. The
environmental information available
for calculating these doses is expected
to be the current gamma exposure rate
at 1 meter height and the relative
abundance of each radionuclide
contributing significantly to that
exposure rate. Calculational models
are available for predicting future
exposure rates as a function of time
due to radioactive decay and
weathering. Weathering is discussed
in WASH-1400, Appendix Ą1 (NR-75),
and information on the relationship
between surface concentrations and
gamma exposure rate at 1 meter is
addressed in reference (DO-88).
Following the incident,
experiments should be conducted to
determine the dose reduction factors
associated with part-time occupancy of
dwellings and workplaces, and with
simple, rapid, decontamination
techniques, so that these factors can
also be applied to the calculation of
dose to persons who are not relocated.
However, these factors should not be
included in the calculation of projected
dose for decisions on relocation.
Relocation decisions can generally
be made on the basis of the first year
projected dose. However? projected
doses during the second year and over
50 years are needed for decisions on
the need for other protective actions for
persons who are not relocated. Dose
conversion factors are therefore needed
for converting environmental
measurements to projected dose during
the first year, second year, and over 50
years following the incident. Of the
two types of environmental
measurements that can be made to
project whole body external gamma
dose, gamma exposure rate in air is the
easiest to make and is the most
directly linked to gamma dose rate.
However, a few measurements of the
second type (radionuclide
concentrations on surfaces) will also be
needed to properly project decreasing
dose rates.
Tables 7-1 and 7-2 provide
information to simplify development
7-8
-------
Table 7-1 Gamma Exposure Rate and Effective Dose Equivalent (Corrected for Radioactive Decay and
Weathering) due to an Initial Uniform Concentration of 1 pCi/m2 on Ground Surface
Radionuclide
Zr-95
Nb-95
Ru-103
Ru-106
Te-132
1-131
1-132
1-133
1-135
Cs-134
Cs-137
Ba-140
La- 140
Half-life
(hours)
1.54E+03
8.41E+02
9.44E+02
8.84E+03
7.82E+01
1.93E+02
2.30E+00
2.08E+01
6.61E+00
1.81E+04
2.65E+05
3.Q7E+02
4.02E+01
Initial exposure8
rate at 1 m
(mR/h
per pCi/m2)
1.21-08
1.3E-08
8.2E-09
3.4E-09
4.0E-09
6.6E-09
3.7E-08
l.OB-08
2.4E-08
2.6E-08
l.OE-08
3.2E-09
3.5E-08
Integrated dose
(weathering factor included)15
year one
(mrem per
pCi/m2)
3.3E-05
(b)
7.1E-06
1.2E-05
3.2E-06
1.3E-06
(b)
2.1E-07
1.6E-07
l.OB-04
4.5E-05
1.1E-05
(b)
year two
(mrem per
pCi/m2)
4.0E-07
(b)
0
3.7E-06
0
0
(b)
0
0
4.7E-05
2.9E-05
0
(b)
0-50 years
(mrem per
pCi/m2)
3.4E-05
(b)
7.1E-06
1.8E-05
3.2E-06
1.3E-06
(b)
2.1E-07
1.6E-07
2.4E-04
6.1E-04
1.1E-05
(b)
Estimated exposure rate at 1 meter above contaminated ground surface. Based on data from reference (DO-88).
bRadionuclides that have short-lived daughters (Zr/Nb-95, Te/I-132, Ru/Rh-106, Cs-137/Ba-137m, Ba/La-140) are assumed to quickly
reach equilibrium. The integrated dose factors listed are the effective gamma dose due to the parent and the daughter. Based on data
from reference (DO-88).
-------
Table 7-2 Exposure Rate and Effective Dose Equivalent (Corrected for Radioactive Decay) due to an Initial
Concentration of 1 pCi/m2
Radionuclide
Zr-95
Nb-95
Ru-103
Ru-106
Te-132
1-131
1-132
1-133
1-135
Cs-134
Cs-137
Ba-140
La-140
Half-life
(hours)
1.54E+03
8.41E+Q2
9.44E+02
8.84E+03
7.82E+01
1.93E+02
2.30E+00
2.08E+01
6.61E+00
1.81E+04
2.65E+05
3.07E+02
4.02E+01
on Ground Surface
Initial exposure*
rate at 1 m
(mR/h
per pCi/m2)
1.2E-08
1.3E-08
8.2E-09
3.4E-09
- 4.0E-09
6.61-09
3.7E-08
l.OE-08
2.4E-08
2.6E-08
l.OE-08
3.2E-09
3.5E-08
Integrated dose
(weathering factor not included)1*
year one
(mrem per
pCi/m2)
3.8E-05
(b)
7.8E-06
1.5E-05
3.3E-06
1.3E-06
(b)
2.1E-07
1.6E-07
1.3E-04
6.0E-05
1.2E-05
(b)
year two
(mrem per
pCi/m2)
8.0E-07
(b)
0
7.6E-06
0
0
(b)
0
0
9.6E-05
5.9E-05
0
(b)
0-50 years
(mrem per
pCi/m2)
3.9E-05
(b)
7.8E-06
3.0E-05
3.3E-06
1.3E-06
(b)
2.1E-07
1.6E-07
4.7E-04
1.8E-03
1.2E-05
(b)
"Estimated exposure rate at 1 meter above contaminated ground surface. Based on data from reference (DO-88).
bRadionuclides that have short-lived daughters {Zr/Nb-95, Eu/Kh-106, Te/I-132, Cs-137/Ba-137m, Ba/La-140) are assumed to quickly
reach equilibrium. The integrated dose factors listed are the effective gamma dose due to the parent and the daughter. Based on data
from reference (DO-88).
-------
of dose conversion factors through the
use of data on the radionuclide mix, as
determined from environmental
measurements. These tables list the
deposited radionuclides most likely to
be the major contributors to dose from
incidents at nuclear power facilities.
In addition to providing integrated,
effective doses per unit of surface
concentration, they provide, in column
three, the exposure rate (mR/h) in air
per unit of surface contamination. All
exposure rate values are based on
those given in reference (DO-88). They
were estimated from the total body
photon dose rate conversion factors for
exposure at 1 m above the ground
surface. Since the ratio of effective
dose to air exposure is about 0.7,
dividing the effective dose rate by 0.7
results in an estimate of the exposure
rate in air. The integrated effective
doses are based on dose conversion
factors also listed in reference (DO-88).
Table 7-1 takes into account both
radioactive decay and weathering,
whereas the values in Table 7-2 include
only radioactive decay. The effect of
weathering is uncertain and will vary
depending on the type of weather, type
of surface, and the chemical form of the
radionuclides. The user may choose
either table depending on the
confidence accorded the assumed
weathering factors.
The following steps can be used to
develop dose conversion factors to
calculate projected future doses from
gamma exposure rate measurements
for specific mixes of radionuclides:
1. Using spectral analysis of gamma
emissions from an environmental
sample of deposited radioactivity,
determine the relative abundance of
the principal gamma emitting
radionuclides. Analyses of uniform
samples from several different locations
may be necessary to determine whether
the relative concentrations of
radionuclides are constant. The results
may be expressed as the activity (pCi)
of each radionuclide in the sample.
2. Multiply each activity from step 1
by the corresponding values in column
3 of Table 7-1 or Table 7-2 (depending
on whether or not weathering is to be
considered) to determine the relative
contribution to the gamma exposure
rate (mR/h) at 1-meter height for each
radionuclide. Sum the results for each
sample.
3. Similarly, multiply each activity
from step 1 by the corresponding
values in columns 4, 5, and 6 to
determine the Ist-year, 2nd-year, and
50-year relative integrated doses
contributed by each radionuclide. Sum
these results for each sample.
Radionuclides listed in Tables 7-1 and
7-2 that have short-lived daughters
(Zr/Nb-95, Te/I-132, Ru/Rh-106,
Cs-137/Ba-137m» Ba/La-140) were
assumed to be in equilibrium with
their daughters when the tabulated
values for integrated dose were
calculated. Since the values for the
parents include the total doge from the
parent and the daughter, do not double
count these daughters in the sum. (In
the cases of Cs-137/Ba-137m, and
Ru-106/Rh-106, the parents are not
gamma emitters, so the listed exposure
rates and doses are actually those from
the daughters alone.)
7-11
-------
4. Using the results from steps 2 and
3, the relevant dose conversion factors,
DCF, for each sample are then given
by:
where Hf = effective dose equiva-
lent for radionuclide i
(mrem),
Xt = gamma exposure rate for
radionuclide i (mR/h)
n = the number of radio-
nuclides in the sample.
Since the samples represented in the
numerator and denominator are
identical, the effect of the size of the
sample cancels.
These dose conversion factors may
be applied to any measured gamma
exposure rate for which the relative
concentrations of radionuclides are the
same as those in the sample that was
analyzed.
The following example
demonstrates the use of the above
procedures for calculating a DCF. For
purposes of the example it is assumed
that environmental measurements
revealed a mix of radionuclides as
shown in column 3 of Table 7-3. The
(relative) exposure rate conversion
factors in column 4 of Table 7-3 are
taken from column 3 of Table 7-1. The
(relative) exposure rates in column 5
are the products of columns 3 and 4.
The (relative) doses for individual
radionuclides in columns 6, 7, and 8
were calculated by multiplying the
concentrations in column 3 by the dose
conversion factors in columns 4, 5, and
6 of Table 7-1, respectively. (Columns
4, 5, and 6 of Table 7-2, which do not
include weathering, could have been
used instead of those in Table 7-1.)
For this example, the conversion
factor for dose in the first year was
obtained for the assumed radionuclide
mix from the totals of columns 5 and 6
of Table 7-3, which indicate that a
calculated dose of 0.023 mrem in the
first year corresponds to an initial
exposure rate of 1.5E-4 mR/h.
Therefore, the first year dose
conversion factor (DCFX) for this
example is 150 mrem for each mR/h
measured at the beginning of the
period.
This DCF may be multiplied by
any gamma exposure rate
measurement to estimate the dose in
the first year for locations where the
exposure rate is produced by a
radionuclide mix the same as assumed
for calculating the DCF, and where
weathering affects the exposure rate in
the same manner as assumed. For
example, if a gamma exposure rate
measurement were taken at the
location where the contamination
sample in Table 7-3 was taken, this
exposure rate could be multiplied by
the DCF calculated in the above
example to obtain the projected first
year dose at that point. Based on the
example analysis and a relocation PAG
of 2 rem, for this case the exposure
rate at the boundary of the restricted
zone should be no greater than
7-12
-------
Table 7-3 Example8 Calculation of Dose Conversion Factors for Gamma Exposure Rate Measurements Based on
Measured Isotopic Concentrations1*
Measured
Radionuclide Half-life concentration
(hours) (pCi/sampled)
1-131
Te-132
1-132
Ru-103
Rh-106f
-------
2000 mrem
150 mrem/mR/h
= 13 mR/h,
if the contribution to effective dose
from inhalation of resuspended
radioactive materials is zero (See
Section 7.3.2). The example DCF for
the second year and 50 years are
obtained by a similar process, yielding
DCFs of 31 and 370 mrem per mE/h,
respectively.
The ratio of the second year to first
year dose is 31/150 = 0.21. If this is
the case, persons not relocated on the
basis of a 2 rem PAG should, for this
example, receive no more than 0.21 x 2
= 0.4 rem in year 2. Similarly, the
dose in fifty years should be no more
than 4.9 rem. Actual doses should be
less than these values to the extent
that exposure rates are reduced by
shielding from structures and by
decontamination.
Prior to reaching conclusions
regarding the gamma exposure rate
that would correspond to the relocation
PAG, one would need to verify by
multiple sampling the consistency of
the relative abundance of specific
radionuclides as well as the relative
importance of the inhalation pathway.
Dose conversion factors will change
as a function of the radiological
makeup of the deposited material.
Therefore, dose conversion factors must
be calculated based on the best current
information following the incident.
Since the relative concentrations will
change as a function of time due to
different decay rates, dose conversion
factors must be calculated for specific
measurement times of interest. By
calculating the decay of the original
sample(s), a plot of dose conversion
factors (mrem per mR/h) as a function
of time after the incident can be
developed. As weathering changes the
radionuclide mix, and as more is
learned about other dose reduction
mechanisms, such predictions of dose
conversion factors may require
adjustment.
7.3.2 Inhalation Dose Projection
It can be shown, for the mixture of
radionuclides assumed to be deposited
from postulated reactor incidents, and
an assumed average resuspension
factor of 10"6 m"1, that the effective dose
from inhalation is small compared to
the corresponding effective dose from
external exposure to gamma radiation.
However, air sample analyses should
be performed for specific situations
(e.g., areas of average and high
dynamic activity) to determine the
magnitude of possible inhalation
exposure. The 50-year committed
effective dose equivalent (Hgo) resulting
from the inhalation of resuspended
airborne radioactive materials is
calculated as follows:
= I x DCF
(1)
where
/ = total intake (uCi), and
DCF = committed effective dose
equivalent per unit intake
(rem/uCi).
It is assumed that the intake rate
will decrease with time due to
7-14
-------
radioactive decay and weathering. No
model is available to calculate the
effect of weathering on resuspension of
deposited materials, so the model
developed for calculating its effect on
gamma exposure rate (NR-75) is
assumed to be valid. This should
provide conservative results. The total
intake (I) from inhalation over time t
may be calculated for each
radionuclide, using the following
equation:
= BCn
0.37
0.63
(2)
where
B = average breathing rate for
adults
= 1.051+4 ma/a (EP-88),
C0 = initial measured concentration of
the resuspended radionuclide in
air(pCi/m8),
t = time during which radionuclides
are inhaled (a),
A! = radioactive decay constant (a"1),
A2 = assumed weathering decay
constant for 63 percent of the
deposited activity, taken as 1.13
a1 (NR-75), and
A3 = assumed weathering decay
constant for 37 percent of the
deposited activity, taken as 7.48
E-3 a'1 (NR-75).
Table 7-4 tabulates results
ealculated.using the above assumptions
for weathering. The table contains
factors relating the committed effective
dose from exposure during the first and
second years after the incident to an
initial air concentration of 1 pCi/m3 for
each of the principal radionuclides
expected to be of concern from reactor
incidents. The dose conversion factors
are taken from FGR-11 (EP-88).
Parent radionuclides and their short
lived daughters are grouped together
because these dose conversion factors
are based on the assumption that both
parents and daughters will occur in
equal concentrations and will decay
with the half life of the parent.
Therefore, measured concentrations of
the short lived daughters should.be
ignored and only the parent
concentrations should be used in
calculating long term projected doses.
Table 7-4 lists factors which
include the effects of both weathering
and radioactive decay, as well as those
that include only the effects of
radioactive decay. Users of these data
should decide which factors to use
based on their confidence on the
applicability of the weathering models
used (NR-75) to their environment.
The committed effective dose
equivalent is calculated by multiplying
the measured initial air concentration
(pCi/ms) for each radionuclide of
concern by the appropriate factor from
the table and summing the results.
This sum may then be added to the
corresponding external whole body
gamma dose to yield the total com-
7-15
-------
Table 7-4
Dose Conversion Factors for Inhalation of Resuspended Material*
Committed effective dose equivalent per unit air concentration
at the beginning of year one (mrem per pCi/jn3)
Considering radioactive
decay and weathering
Considering radioactive
decay only
Radionuclideb
Sr-90/Y-90
Zr-95/Nb-95
Ru-103
Eu-106/Rh-106
Te- 132/1-132
1-131
Cs-134
Cs-137/Ba-137m
Ba-140/La-140
Ce-144/Pr-144
Lung class"
Y/Y
Y/Y
Y
Y/D
W/D
D
D
D/D
D/W
Y/Y
Year one
l.OE+1
6JE-2
1JE-2
2.8EO
1.3E-3
1.1E-2
3.1E-1
2.5E-1
4.4E-3
2.010
Year two
5.510
-
-
l.OEO
-
"
1.5E-1
1.4E-1
-
4.2E-1
Year one
1.4E+1
7.9E-2
1.5E-2
3.7E 0
1.3E-3
1.1E-2
4.1B-1
3.3E-1
4.71-3
2.7EO
Year two
1.3B+1
-
-
1.9EO
-
-
3.0E-1
3.2E-1
_
9.8E-1
Calculated msing the dose factors in EP-88, Table 2.1.
bShort lived daughters are not listed separately because the entries include the dose from both the daughter and the parent. These
factors are based on the concentration of the parent only, at the beginning of the exposure period.
The lung clearance class chosen is that which results in the highest dose conversion factor.
-------
mitted effective dose equivalent from
these two pathways.
The PAGs include a guide for dose
to skin which is 50 times the
magnitude of the PAG for effective
dose. Analysis (AR-89) indicates that
this guide is not likely to be controlling
for radionuclide mixes expected to be
associated with nuclear power plant
incidents. Dose conversion factors are
provided in Table 7-5 for use in case of
incidents where the source term
consists primarily of pure beta
emitters. The skin dose from each
radionuclide may be calculated by
multiplying the measured
concentration (pCi/m2) by the
corresponding dose conversion factor in
the table. This will yield the first year
beta dose to the skin at one meter
height from exposure to deposited
materials plus the estimated dose to
the skin from materials deposited on
the skin as a result of being in the
contaminated area. These factors are
calculated based on information in
Reference AR-89, which used
weathering factors that apply for
gamma radiation and would, therefore,
be conservative for application to beta
radiation. Calculated doses based on
these factors should be higher than the
doses that would be received.
7.4 Priorities
In most cases protective actions
during the intermediate phase will be
carried out oyer a period of many days.
It is therefore useful to consider what
priorities are appropriate. Further, for
situations where the affected area is so
large that it is impractical to relocate
all of the public, especially from areas
exceeding the PAGs by only a small
amount, priorities are needed for
protective actions. The following
priorities are appropriate:
1. As a first priority, assure that all
persons are protected from doses that
could cause acute health effects from
all. exposure pathways, including
previous exposure to the plume.
2. Recommend the application of
simple decontamination techniques and
that persons remain indoors as much
as possible to reduce exposure rates.
3. Establish priorities for relocation
with emphasis on high exposure rate
areas and pregnant women (especially
those in the 8th to 15th week of
pregnancy).
7.5 Reentry
After the restricted zone is
established, persons will need to
reenter for a variety of reasons,
including recovery activities, retrieval
of property, security patrol, operation
of vital services, and, in some cases,
care and feeding of farm and other
animals. It may be possible to quickly
decontaminate access ways to vital
institutions and businesses in certain
areas so that they can be occupied by
adults either for living (e.g.,
institutions such as nursing homes,
and hospitals) or for employment.
Clearance - of these areas for such
occupancy will require dose reduction
to comply with occupational exposure
7-17
-------
Table 7-5 Skin Beta Dose Conversion Factors for Deposited Radionuelides8
Radiomielide
Co-58
Co-60
Eb-86
Sr-89
Sr-90
Y-90
Y-91
Zr-95
Nb-95
Mo-99
Tc-99m
Bu-103
Ru-106°
Rh-105
Sb-127
Te-127
Te-127m
Te-129
Te-129m
Te-131m
Te-132
1-131
1-132
Cs-134
Cs-136°
Cs-137c
Ba-140
La-140
Ce-141
Dose conversion factor15
(mrem per pCi/m2)
Radioactive decay
plus weathering
1.2E-7
4.2E-7
6.3E-5
1.51-4
1.2E-5
2.2E-4
1.6E-4
7.2E-7
6.1E-7
4.4E-6
7.7E-9
6.8E-7
6.4E-7
6.5E-8
3.4E-6
l.OE-6
7.8E-7
5.0E-7 ,
3.4E-5
2.9E-7
5.4E-9
8.5E-7
5.0E-5
2.6E-5
1.4E-7
2.1E-5
9.1E-6
1.2E-5
6.6E-7
Radioactive
decay only
1.4E-7
5.6E-7
6.7E-5
1.6E-4
1.7E-5
2.9E-4
1.9E-4
8.3E-7
7.4E-7
4.6E-6
7.7E-9
7.8E-7
8.7E-7
6.6E-8
3.4E-6
l.OE-6
9.5E-7
5.0E-7
3.6E-5
2.9E-7
5.4E-9
8.7E-7
5.0E-5
3.3E-5
3.7E-7
2.9E-5
9.6E-6
1.3E-5
7.1E-7
7-18
-------
Table 7-5, Continued
Radionuclide
Dose conversion factors1*
(mrem per pCi/m2)
Ce-143
Ce-144c
Pr-143
Nd-147
Np-239
Am-241
Radioactive decay
plus weathering
2.3E-6
8.7E-7
1.3E-5
4.3E-6
3.4E-8
4.6E-8
Radioactive
decay only
2.3E-6
1.1E-6
1.4E-5
4.5E-6
3.4E-8
6.4E-8
aBased on data from reference AE-89.
bDose equivalent integrated for a one-year exposure at one meter height plus the estimated dose to
the skin from materials deposited on the skin as a result of being in the contaminated area.
"Contributions from short-lived (one hour or less) decay products are included in dose factors for the
parent radionuclides (i.e,, Rh-106, Ba-136, Ba-137, and Pr-144).
limits (EP-87). Dose projections for
individuals should take into account
the maximum expected duration of
exposure.
Persons working in areas inside the
restricted zone should operate under
the controlled conditions normally
established for occupational exposure
(EP-87).
7.6 Surface Contamination Control
Areas under the plume can be
expected to contain deposited
radioactive materials if aerosols or
partieulate materials were released
during the incident. In extreme cases,
individuals and equipment may be
highly contaminated, and screening
stations will be required for emergency
monitoring and decontamination of
individuals and to evaluate the need
for medical evaluation. Equipment
should be checked at this point and
decontaminated as necessary to avoid
the spread of contamination to other
locations. This screening service would,
be required for only a few days
following plume passage until all such
7-19
-------
persons have been evacuated or
relocated.
After the restricted zone is
established, based on the PAGs for
relocation, adults may reenter the
restricted zone under controlled
conditions in accordance with
occupational exposure standards.
Monitoring stations will be required
along roadways to control surface
contamination at exits from the
restricted zone. Because of the
possibly high background radiation
levels at control points near exits,
significant levels of surface
contamination on persons and
equipment may be undetectable at
these locations. Therefore, additional
monitoring and decontamination
stations may be needed at nearby low
background locations.
Decontamination and other measures
should be implemented to maintain low
exposure rates at monitoring stations.
7.6.1 Considerations and Constraints
Surface contamination limits to
control routine operations at nuclear
facilities and to transport radioactive
material are generally set at levels
lower than are practical for situations
involving high-level, widespread
contamination of the environment.
The principal exposure pathways for
loose surface contamination on persons,
clothing, and equipment are (a)
internal doses from ingestion by direct
transfer, (b) internal doses from
inhalation of resuspended materials, (c)
beta dose to skin from contaminated
skin or clothing or from nearby
surfaces, and (d) dose to the whole
body from external gamma radiation.
Because of the difficulties in
predicting the destiny of uncontrolled
surface contamination, a contaminated
individual or item should not be
released to an unrestricted area unless
contamination levels are low enough
that they produce only a small
increment of risk to health (e.g., less
than 20 percent), compared to the risk
to health from the principle exposure
pathway (e.g., whole body gamma dose)
in areas immediately outside the
restricted zone. On the other hand, a
level of contamination comparable to
that existing on surfaces immediately
outside the restricted zone may be
acceptable on materials leaving the
restricted zone. Otherwise, persons
and equipment occupying areas
immediately outside the restricted zone
would not meet the surface
contamination limits. These two
constraints are used to set permissible
surface contamination limits.
The contamination limit should
also be influenced by the potential for
the contamination to be ingested,
inhaled, or transferred to other
locations. Therefore, it is reasonable to
establish lower limits for surfaces
where contamination is loose than for
surfaces where the contamination is
fixed except for skin. The expected
period of fixed contamination on skin
would be longer so a lower limit would
be justified.
For routine (nonincident)
situations, measurement of gross
7-20
-------
beta-gamma surface contamination
levels is commonly performed with a
thin-window geiger counter (such as a
CDV-700). Since beta-gamma
measurements made with such field
instruments cannot be interpreted in
terms of dose or exposure rate, the
guidance set forth below is related to
the background radiation level in the
area where the measurement is being
made. Supplementary levels are
provided for gamma exposure rates
measured with the beta shield closed.
Guidance levels expressed in this form
should be easily detectable and should
satisfy the above considerations.
Corresponding or lower levels
expressed in units related to
instrument designations may be
adopted for convenience or for ALAEA
determinations. Smears may also be
used to detect loose surface
contamination at very low levels.
However, they are not considered
necessary for emergency response and,
therefore, such guidance is not
provided.
7.6.2 Numerical Relationships
As discussed in Section 7.3.1, a
relationship can be established between
projected first year doses and
instantaneous gamma exposure rates
from properly characterized surface
contamination. Based on assumed
radiological characteristics of releases
from fuel melt accidents, gamma
exposure rates in areas where the
projected dose is equal to the relocation
PAG of 2 rem in the first year may be
in the range of 2 to 5 mR/h during the
first few days following the deposition
from a type SST-2 accident (See
Section E.1.2). (This relationship must
be determined for each specific release
mixture.) Based on relationships in
reference (DO-88) and a mixture of
radionuclides expected to be typical of
an SST-2 type accident, surface
contamination levels of 2xl08 pCi/m2
would correspond approximately to a
gamma exposure rate of 1 mE/h at 1
meter height.
7.6.3 Recommended
Contamination Limits
Surface
Surface contamination must be
controlled both before and after
relocation PAGs are implemented.
Therefore, this section deals with the
control of surface contamination on
persons and equipment being protected
during both the early and intermediate
phases of a nuclear incident.
For emergency situations, the
following general guidance regarding
surface contamination is recommended:
1. Do not delay urgent medical care
for decontamination efforts or for time-
consuming protection of attendants.
2. Do not waste effort trying to
contain contaminated wash water.
3. Do not allow monitoring and
decontamination to delay evacuation
from high or potentially high exposure
rate areas.
4. (Optional provision, for use only if
a major contaminating event occurs,
and rapid early screening is needed.)
7-21
-------
After plume passage, it may be
necessary to establish, emergency
contamination, screening stations in
areas not qualifying as low background
areas. Such should be less than
5 mR/h gamma exposure rate. These
screening stations should be used only
during the early phase and for major
releases of particulate materials to the
atmosphere to monitor persons
emerging from possible high exposure
areas, provide simple (rapid)
decontamination if needed, and make
decisions on whether to send them for
special care or to a monitoring and
decontamination station in a lower
background area. Table 7-6 provides
guidance on surface contamination
levels for use if such centers are
needed,
5. Establish monitoring and personnel
decontamination (bathing) facilities at
evacuation centers or other locations in
low background areas (less than
0,1 mK/h). Encourage evacuated
persons who were exposed in areas
where inhalation of particulate
materials would have warranted
evacuation to bathe, change clothes,
wash clothes, and wash other exposed
surfaces such as cars and trucks and
their contents and then report to these
centers for monitoring. Table 7-7
provides surface contamination
guidance for use at these centers.
These screening levels are examples
derived primarily on the basis of easily
measurable concentrations using
portable instruments.
6. After the restricted zone is
established, set up monitoring and
decontamination stations at from
the restricted zone. Because of the
probably high background radiation
levels at these locations, low levels of
contamination may be undetectable. If
contamination levels are undetectable,
then they probably do not exceed those
in some unrestricted areas occupied by
the exposed population and no
decontamination is required.
Nevertheless, these individuals should
be advised to bathe and change clothes
at their first opportunity and certainly
within the next 24 hours. If, after
decontamination at the boundary of the
restricted zone station, persons still
exceed the limits for this station, they
should be sent for further
decontamination or for medical or other
special attention. As an alternative to
decontamination, contaminated items
other than persons or animals may be
retained in the restricted zone for
radioactive decay.
7. Establish auxiliary monitoring and
decontamination stations in low
background areas (background
than 0.1 mWh). These stations should
be used to achieve ALARA surface
contamination levels. Table 7-7
provides surface contamination
screening levels for use at those
stations.
7-21
-------
Table 7-6 Recommended Surface Contamination Screening Levels for Emergency
Screening of Persons and Other Surfaces at Screening or Monitoring
Stations in High Background Eadiation Areas (0.1 mR/h to 5 mR/h
Gamma Exposure)8
Condition
Geiger-counter shielded-
window reading
Recommended action
Before
decontamination
<2X bkgd and <0.5 mR/h
above background
>2X bkgd or >G.5 mR/h
above background
Unconditional
release
Decontaminate
Equipment may be
stored or disposed
of as appropriate.
After
decontamination
<2X bkgd and <0.5 mR/h
above background
>2X bkgd or >0.5 mR/h
above background
Unconditional
release
Continue to
decontaminate or
refer to low back-
ground monitoring
and d-con station.
Equipment may also
be stored for
decay or disposed
of as appropriate.
"Monitoring stations in such high exposure rate areas are for use only during the early phase of an
incident involving major atmospheric releases of particulates. Otherwise use Table 7-7.
7-23
-------
Table 7-7 Recommended Surface Contamination Screening Levels for Persons
and Other Surfaces at Monitoring Stations in Low Background
Radiation Areas (<0.1 mR/h Gamma Exposure Rate)
Condition
Geiger-counter
thin window3 reading
Recommended action
Before decontamination
After simpleb
decontamination effort
After full6
decontamination effort
<2X bkgd
>2X bkgd
<2Xbkgd
>2X bkgd
<2X bkgd
>2X bkgd
Unconditional release
Decontaminate
Unconditional release
Full decontamination
Unconditional release
Continue to decontaminate
<0.5 mR/hd
persons
Release animals and
equipment
After additional <2Xbkgd
full decontamination effort
>2X bkgd
<0.5 mR/hd
>0.5 mR/hd
Unconditional foil release
Send persons for special
evaluation
Release animals and
equipment
Refer, or use informed
judgment on
further control of animals
and equipment
"Window thickness of approximately 30 mg/cm2 is acceptable. Recommended limits for open
window readings are expressed as twice the existing background (including background) in the
area where measurements are being made. Corresponding levels, expressed in units related to
instrument designations, may be adopted for convenience. Levels higher than twice background
7-24
-------
References
AR-89 Aaberg, Rosanne. Evaluation of Skin
and Ingestion Exposure Pathways, EPA
520/1-89-016, U.S. Environmental Protection
Agency, Washington (1989).
DO-88 U.S. Department of Energy. External
Dose-Rate Conversion Factors for
Calculation of Dose to the Public.
DOE/EH-0070, U.S. Department of Energy,
Washington (1988).
EP-87 U.S. Environmental Protection
Agency. Radiation Protection Guidance to
Federal Agencies for Occupational Exposure.
Federal Register. 52. 2822; January, 1987.
EP-88 U.S. Environmental Protection
Agency. Limiting Values of Radionuclide
Intake and Air Concentration and Dose
Conversion Factors for Inhalation,
Submersion, and Ingestion. EPA
520/1-88-020, U.S. Environmental Protection
Agency, Washington (1988).
FE-85 Federal Emergency Management
Agency. Federal Radiological Emergency
Response Plan (FRERPJ. Federal Register.
50, 46542; November 8, 1985.
NR-75 U. S. Nuclear Regulatory
Commission. Reactor Safety Study. An
Assessment of Accident Risks in U. S.
Commercial Nuclear Power Plants.
WASH-1400, NUREG-75/014, U.S. Nuclear
Regulatory Commission, Washington, (1975).
(footnote continued)
(not to exceed the meter reading corresponding to 0.1 mR/h) may be used to speed the monitoring
of evacuees in very low background areas.
b Flushing with water and wiping is an example of a simple decontamination effort.
c Washing or scrubbing with soap or solvent followed by flushing is an example of a full
decontamination effort. '
& Closed shield reading including background. .•.••.:•-•
7-25
-------
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-------
CHAPTER 8
Radiation Protection Guides for the Late Phase (Recovery)
(Reserved)
8-1
-------
Page Intentionally Blank
-------
APPENDIX A
Glossary
-------
Page Intentionally Blank
-------
APPENDIX A
Glossary
The following definitions apply
specifically to terms used in this
manual.
Acute health effects: Prompt radiation
effects (those that would be observable
within a short period of time) for which
the severity of the effect varies with
the dose, and for which a practical
threshold exist.
Ablation: The functional destruction of
an organ through surgery or exposure
to large doses of radiation.
Buffer zone: An expanded portion of
the restricted zone selected for
temporary radiation protection controls
until the stability of radioactivity levels
in the area is confirmed.
Cloudshine: Gamma radiation from
radioactive materials in an airborne
plume.
Committed dose: The radiation dose
due to radionuclides in the body over a
50-year period following their
inhalation or ingestion.
Delayed health effects: Radiation
effects which are manifested long after
the relevant exposure. The vast
majority are stochastic, that is, the
severity is independent of dose and the
probability is assumed to be
proportional to the dose, without
threshold.
Derived response level (DRL): A level
of radioactivity in an environmental
medium that would be expected to
produce a dose equal to its
corresponding Protective Action Guide.
Dose conversion factor: Any factor that
is used to change an environmental
measurement to dose in the units of
concern.
Dose equivalent: The product of the
absorbed dose in rad, a quality factor
related to the biological effectiveness of
the radiation involved and any other
modifying factors.
Effective dose equivalent: The sum of
the products of the dose equivalent to
each organ and a weighting factor,
where the weighting factor is the ratio
of the risk of mortality from delayed
health effects arising from irradiation
of a particular organ or tissue to the
total risk of mortality from delayed
health effects when the whole body is
irradiated uniformly to the same dose.
Evacuation: The urgent removal of
people from an area to avoid or reduce
high-level, short-term exposure, usually
from the plume or from deposited
activity. Evacuation may be a
A-l
-------
preemptive action taken in response to
a facility condition rather than an
actual release.
Genetic effect: An effect in a
descendant resulting from the
modification of genetic material in a
parent.
Groundshine: Gamma radiation from
radioactive materials deposited on the
ground.
Incident phase: This guidance
distinguishes three phases of an
incident (or accident): (a) early phase,
(b) intermediate phase, and (c) late
phase.
(a) Early phase: The period at the
beginning of a nuclear incident when
immediate decisions for effective use of
protective actions are required, and
must be based primarily on predictions
of radiological conditions in the
environment. This phase may last
from hours to days. For the purpose of
dose projection, it is assumed to last for
four days.
(b) Intermediate phase: The period
beginning after the incident source and
releases have been brought under
control and reliable environmental
measurements are available for use as
a basis for decisions on additional
protective actions and extending until
these protective actions are terminated.
This phase may overlap the early and
late phases and may last from weeks to
many months. For the purpose of dose
projection, it is assumed to last for one
year.
(c) Late phase: The period
beginning when recovery action
designed to reduce radiation levels in
the environment to permanently
acceptable levels are commenced, and
ending when all recovery actions have
been completed. This period may
extend from months to years (also
referred to as the recovery phase).
Linear Energy Transfer (LET): A
measure of the ability of biological
material to absorb ionizing radiation;
specifically, for charged particles
traversing a medium, the energy lost
per unit length of path as a result of
those collisions with elections in which
the energy loss is less than a specified
maximum value. A similar quantity
may be defined for photons.
Nuclear incident: An event or series of
events, either deliberate or accidental,
leading to the release, or potential
release, into the environment of
radioactive materials in sufficient
quantity to warrant consideration of
protective actions.
Prodromal effects: The forewarning
symptoms of more serious health
effects.
Projected dose: Future dose calculated
for a specified time period on the basis
of estimated or measured initial
concentrations of radionuclides or
exposure rates and in the absence of
protective actions.
Protective action: An activity
conducted in response to an incident or
potential incident to avoid or reduce
radiation dose to members of the public
A-2
-------
(sometimes called a protective
measure).
Protective Action Guide (PAG): The
projected dose to reference man, or
other defined individual, from an
accidental release of radioactive
material at which a specific protective
action to reduce or avoid that dose is
warranted.
Recovery: The process of reducing
radiation exposure rates and
concentrations of radioactive material
in the environment to levels acceptable
for unconditional occupancy or use.
Reentry: Temporary entry into a
restricted zone under controlled
conditions,
Relocation: The removal or continued
exclusion of people (households) from
contaminated areas to avoid chronic
radiation exposure.
Restricted zone: An area with
controlled access from which the
population has been relocated.
Return: The reoccupation of areas
cleared for unrestricted residence or
use.
Sheltering: The use of a structure for
radiation protection from an airborne
plume and/or deposited radioactive
materials.
Short-lived daughters: Radioactive
progeny of radioactive isotopes that
have half-lives on the order of a few
hours or less.
Weathering factor: The fraction of
radioactivity remaining after being
affected by average weather conditions
for a specified period of time.
Weighting factor: A factor chosen to
approximate the ratio of the risk of
fatal cancer from the irradiation of a
specific tissue to the risk when the
whole body is irradiated uniformly to
the same dose.
Whole body dose: Dose resulting from
uniform exposure of the entire body to
either internal or external sources of
radiation.
A-3
-------
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APPENDIX B
Risks To Health From Radiation Doses
That May Result From
Nuclear Incidents
-------
Page Intentionally Blank
-------
Contents
Page
B.I Introduction B-l
B.1.1 Units of Dose B-l
B.1.2 Principles for Establishing Protective
Action Guides B-2
B.2 Acute Effects B-3
B.2.1 Review of Acute Effects B-3
B.2.1.1 The Median Dose for Lethality B-4
B.2.1.2 Variation of Response for Lethality B-5
B.2.1.3 Estimated LethaHty vs Dose for Man B-7
B.2.1.4 Threshold Dose Levels for Acute Effects B-10
B.2.1.5 Acute Effects in the Thyroid B-12
B.2.1.6 Acute Effects in the Skin B-12
B.2.1.7 Clinical Pathophysiological Effects B-12
B.2.2 Summary and Conclusions Regarding Acute Effects B-17
B.3 Mental Retardation B-17
B.4 Delayed Health Effects B-18
B.4.1 Cancer B-18
B.4.1.1 Thyroid B-20
B.4.1.2 Skin B-21
B.4.1.3 Fetus B-21
B.4.1.4 Age Dependence of Doses B-22
B.4.2 Genetic Risk : B-23
B.4.3 Summary of Risks of Delayed Effects B-23
B.4.4 Risks Associated with Other Radiation Standards B-23
References B-25
111
-------
Figures
Page
B-l Acute Health Effects as a Function of Whole Body Dose B-9
Tables
B-l Radiation Doses Causing Acute Injury to Organs B-14
B-2 Acute Radiation Exposure as a Function of Rad
Equivalent Therapy Units (rets) B-15
B-3 Radiation Exposure to Organs Estimated to Cause
Clinical Pathophysiological Effects Within 5 Years
to 0.1 Percent of the Exposed Population B-16
B-4 Average Risk of Delayed Health Effects in a Population B-24
IV
-------
APPENDIX B
Risks To Health From Radiation Doses
That May Result From
Nuclear Incidents
B.I Introduction
This appendix reviews the risks
from, radiation that form the basis for
the choice of Protective Action Guides
(PAGs) for the response to a nuclear
incident, as well as the choice of limits
for occupational exposure during a
nuclear incident.
B.I.I Units of Dose
The objective of protective action
is to reduce the risk to health from
exposure to radiation. Ideally, one
would like to assure the same level of
protection for each member of the
population. However, protective
actions cannot take into account
individual variations in
radiosensitivity, since these are not
known. Therefore, these PAGs are
based on assumed average values of
risk. We further assume that these
risks are proportional to the dose, for
any level of dose below the threshold
for acute effects (see Section B.2.).
The dose from exposure to
radioactive materials may be delivered
during the period of environmental
exposure only (e.g., external gamma
radiation), or over a longer period (e.g.,
inhaled radionuclides which deposit in
body organs). In the latter case, dose
is delivered not only at the time of
intake from the environment, but
continues until all of the radioactive
material has decayed or is eliminated
from the body. Because of the variable
time over which such doses may be
delivered, the PAGs are expressed in
terms of a quantity called the
"committed dose." Conceptually,
committed dose is the dose delivered
over an individual's remaining lifetime
following an intake of radioactive
material. However, due to differences
in physiology and remaining years of
life, the committed dose to a child from
internal radioactivity may differ from
that to an adult. For simplicity, adult
physiology and a remaining lifetime of
50 years are assumed for the purpose
of calculating committed doses.
Another important consideration is
that different parts of the body are at
different risk from the same dose.
Since the objective of protective actions
is the reduction of health risk, it is
appropriate to use a quantity called
"effective dose." Effective dose is the
sum of the products of the dose to each
organ or tissue of the body and a
weighting factor representing the
relative risk. These weighting factors
(IC-77) are chosen as the ratio of
mortality (from delayed health effects)
from irradiation of particular organs or
tissues to the total risk of such
B-l
-------
mortality when the whole body is
irradiated uniformly at the same dose.
Finally, doses from different types
of radiation (e.g. alpha, beta, gamma,
and neutron radiation) have different
biological effectiveness. These
differences are customarily accounted
for, for purposes of radiation protection,
by multiplicative modifying factors. A
dose modified by these factors is
designated the "dose equivalent." The
PAGs are therefore expressed in terms
of committed effective dose equivalent.
The PAGs are augmented by limits for
a few specific organs (skin and thyroid)
which exhibit special sensitivity. These
are expressed in terms of committed
dose equivalent (rem). In the process
of developing PAG values, it is
necessary to evaluate the threshold
dose levels for acute health effects.
These levels are generally expressed in
terms of absorbed dose (rad) to the
whole body from short term (one month
or less) exposure. Other units
(Roentgens, rem, and rets) are also
used in information cited from various
references. They are all approximately
numerically equivalent to rads in terms
of the risk of acute health effects from
beta and gamma radiation.
PAGs are intended to apply to all
individuals in a population other than
workers performing emergency
services. However, there may be
identifiable groups that have different
average sensitivity to radiation or,
because of their living situation, will
receive higher or lower doses. In
addition, some groups may be at
greater risk from taking a given
protective action. These factors are
separately considered, when it is
appropriate, in establishing values for
the PAGs.
B.1.2 Principles for Establishing
Protective Action Guides
The following four principles
provide the basis for establishing
values for Protective Action Guides:
1. Acute effects on health (those that
would be observable within a short
period of time and which have a dose
threshold below which they are not
likely to occur) should be avoided.
2. The risk of delayed effects on health
(primarily cancer and genetic effects,
for which linear nonthreshold
relationships to dose are assumed)
should not exceed upper bounds that
are judged to be adequately protective
of public health, under emergency
conditions, and are reasonably
achievable.
3. PAGs should not be higher than
justified on the basis of optimization of
cost and the collective risk of effects on
health. That is, any reduction of risk
to public health achievable at
acceptable cost should be carried out.
4. Regardless of the above principles,
the risk to health from a protective
action should not itself exceed the risk
to health from the dose that would be
avoided.
With the exception of the second,
these principles are similar to those set
forth by the International Commission
B-2
-------
on Radiological Protection (IC-84b) as
the basis for establishing intervention
levels for nuclear accidents. We
examine, below, the basis for
estimating effects on health for use in
applying the first two of these
principles.
B.2 Acute Effects
This section provides information
relevant to the first principle:
avoidance of acute effects on health
from radiation.
Acute radiation health effects are
those clinically observable effects on
health which are manifested within
two or three months after exposure.
Their severity depends on the amount
of radiation dose that is received.
Acute effects do not occur unless the
dose is relatively large, and there is
generally a level of dose (i.e., threshold)
below which an effect is not expected to
occur. Acute effects may be classified
as severe or nonsevere clinical
pathophysiological effects. Severe
pathophysiological effects are those
which have clinically observable
symptoms and may lead to serious
disease and death. Other patho-
physiological effects, such as
hematologic deficiencies, temporary
infertility, and chromosome changes,
are not considered to be severe, but
may be detrimental in varying degrees.
Some pathophysiological effects, such
as erythema, nonmalignant skin
damage, loss of appetite, nausea,
fatigue, and diarrhea, when associated
with whole body gamma or neutron
exposure, are prodromal (forewarning
of more serious pathophysiological
effects, including death).
B.2.1 Review of Acute Effects
This section summarizes the
results of a literature survey of reports
of acute effects from short-term
(arbitrarily taken as received in one
month or less) radiation exposure in
some detail. Many reports of observed
effects at lower doses differ, and some
are contradictory; however, most have
been included for the sake of
completeness. The results of the
detailed review described in this
Section are summarized in Section
B.2.2.
The biological response to the
rapid delivery of large radiation doses
to man has been studied since the end
of World War II. Dose-response
relationships for prodromal
(forewarning) symptoms and for death
within 60 days have been developed
from data on the Japanese A-bomb
survivors, Marshall Island natives
exposed to fallout, and patients
undergoing radiotherapy. This work
has been supplemented by a number of
animal studies under controlled
conditions.
The animal studies, usually using
lethality as the end point, show that
many factors can influence the degree
of response. The rate at which the
dose is delivered can affect the median
lethal dose (LD50) in many species,
particularly at dose rates less than
5 R/min (PA-68a; BA-68). However, in
primates there is less than a 50
B-3
-------
percent increase in the LDSO as dose
rates are decreased from 50 K/min to
about 0.01 R/min (PA-68a). There is
good evidence of species specificity
(PA-68a; BO-69). The LDSO ranges
from about 100 rad for burros to over
1000 rad for lagomorphs (e.g., rabbits).
Response is modulated by: age (CA-68),
extent of shielding (partial body
irradiation) (BO-65), radiation quality
(PA-68a; BO-69), diet, and state of
health (CA-68).
While animal studies provide
support and supplemental information,
they cannot be used to infer the
response for man. This lack of
comparability of man and animals had
already been noted by a review
committee for the National Academy of
Sciences as early as 1956, in
considering the length of time over
which acute effects might be
expressed (NA-56): "Thus, an LD50,
30-day consideration is inadequate to
characterize the acute lethal dose
response of man, and an LD50, 60 days
would be preferable."1
Several estimates of the levels at
which acute effects of radiation occur
in man have been published. For
example, an early estimate of the
1The committee (known as the BEAR
Committee) also noted "The reservation must
be made here that the exposed Japanese
population was heterogeneous with respect to
age, sex, physical condition and degree of
added trauma from burns or blast. The extent
to which these factors affected the survival
time has not been determined. In studies on
laboratory animals the converse is
true-homogeneous populations are studied"
(NA-56, p.I-6).
dose-response curves for prodromal
(forewarning) symptoms and for
lethality was made in the first edition
of "The Effects of Nuclear Weapons"
(1957) (GL-57), and a more recent and
well documented estimate is given in a
NASA publication, "Radiobiological
Factors in Manned Space Flight"
(LA-67).
B.2.1.1 The Median Dose for Lethality
The radiation dose that would
cause 50 percent mortality in 60 days
was estimated as 450 Roentgens in
early reports (NA-56; GL-57; RD-51).
The National Commission on Radiation
Protection and Measurements (NCKP)
calculated that this would correspond
to a midline absorbed dose of 315 rad
(NC-74). The ratio of 315 rad to 450
Roentgens is 0.70, which is about the
estimated ratio of the active marrow
dose, in rads, to the tissue kerma in
air, in rads (KE-80). The BEAR
Committee noted that the customary
reference to LD50 in animal studies, as
if it were a specific property,
independent of age, was not justifiable
(NA-56): "...it is evident, now, that
the susceptibility of a whole population
is not describable by a single LD50.
The published values are usually
obtained for young adults and are
therefore maximal or nearly maximal
for the strain. In attempts to estimate
LD60 in man, this age dependence
should be taken into consideration"
(NA-56, pp.4-5). They observed that
the LD60 approximately doubled as rats
went from neonates to young adults
and then decreased as the animals
aged further. Finally, the BEAR
B-4
-------
Committee concluded: "The situation is
complex, and it became evident that it
is not possible to extrapolate with
confidence from one condition of
radiation exposure to another, or from
animal data to man" (NA-56, p.I-8).
Nevertheless, results from animal
studies can aid in interpreting the
human data that are available.
The NCRP suggested the LD50/60
might be 10 to 20 percent lower for the
old, very young, or sick, and somewhat
greater for healthy adults of
intermediate age (RD-51). Other
estimates of adult LD50/60 have ranged
from about 300 rad to 243 + 22 rad.
These lower estimates are apparently
based on a ratio of air to tissue dose
similar to those calculated for midline
organs in the body; 0.54 to 0.66 (KE-80;
OB-76; KO-81).
A NASA panel examined all
patient and accident studies, tried to
remove confounding factors, and
concluded, "On this basis, it may be
assumed that the LD50 value of 286 rad
obtained by a normal fit to the patient
data is the preferred value for healthy
man" (LA-67).
An LD
50/60
of 286 + 25 rad
(standard deviation) midline absorbed
dose and an absorbed dose/air dose
ratio of 0.66, suggested by the National
Academy of Science (LA-67), is
probably a reasonable value for healthy
males. In the absence of more
complete information, we assume that
a value of 300 rad +_ 30 rad is a
reasonable reflection of current
uncertainties for average members of
the population.
B.2.1.2 Variation of Response for
Lethality
Uncertainty in the dose-response
function for acute effects has been
expressed in various ways. The slope
of the estimated dose-response function
has most commonly been estimated on
the basis of the percent difference in
the LD50 and the LD159 or LD84-]t (one
standard deviation from the LD50), as
was done by NASA (GL-57). These and
other parameters derived in a similar
manner describe the uncertainty in the
central risk estimate for the
dose-response function.
Another means is to use an
estimate of upper and lower bounds for
the central risk estimate, e.g., the 95
percent fiducial limits. At any given
response point on the dose-response
function, for example, the LD10, the
dose causing that response has a
95 percent probability of lying between
the lower and upper bounds of the
95 percent fiducial limit for that point.
To estimate this value, probit analyses
were run for each species using data in
published reports (KO-81; TA-71). This
provided estimates for each species for
comparability analyses. The 95 percent
fiducial limits at the LD50 response for
LD50/30 studies averaged +9 percent
(range -9 to +26 percent) and for LD50/60
studies +.17 percent (range -20 to +45
percent). At the LD16 response, values
were +.16 percent (range -12 to +50
percent) for LD15/30 data and
+.26 percent (range -20 to +65 percent)
for LD15/60 data. For the LD85 response,
values were +17 percent (range -36 to
+36 percent) for the LD85/80 data and
B-5
-------
+24 percent (range -46 to +31 percent)
for LD85/60 data.
The differences in the magnitude
of the fiducial limits are a function of
the differences in age, sex, radiation
quality, degree of homogeneity of the
experimental animals, husbandry, and
other factors. The estimates show that
the fiducial limits, expressed as a
percent of the dose at any response, get
greater the farther from the LD50 the
estimate is made. For the purpose of
estimating fiducial limits for humans,
the 95 percent fiducial limits will be
considered to be LD15 +_15 percent, LD50
HhiO percent, and LD85 +15 percent.
Beyond these response levels, the
fiducial limits are too uncertain and
should not be used.
If the median lethal dose, LD50/60,
is taken as 300 ±30 rad midline
absorbed dose, the response to higher
and lower doses depends on the degree
of biological variation in the exposed
population. The NASA panel decided
the wide variation in the sensitivity of
patients was a reflection of the
heterogeneity of the sample; and that
the variation in sensitivity, the slope of
the central estimate of the response
function, would be stated in the form of
one standard deviation calculated as
58 percent of the LD50. They further
decided the deviation in the patients
(58 percent) was too great, and the
standard deviation for "normal" man
should be closer to that of dogs and
monkeys (18 percent) (LA-67). (The
rationale for selecting these species
was not given.)
Jones attempted to evaluate the
hematologic syndrome from
mammalian lethality studies using the
ratio of dose to LD50 dose as an
indicator of the steepness of the slope
of the dose-response function (JO-81).
However, he evaluated LD50 studies
only of species having a rather steep
slope, i.e., dogs, monkeys, mice, and
swine. He also looked at several
different statistical models for
dose-response functions and pointed
out the problems caused by different
models and assumptions, particularly
in evaluating the tails of the
dose-response function (less than LD10
and greater than LD90). Jones
recommended using a log-log model,
which he felt provided a better fit at
low doses (JO-81).
Scott and Hahn also evaluated
acute effects from mammalian
lethality, but suggested using a Weibull
model (SC-80). One of the advantages
of the Weibull model is that in addition
to developing the dose-response
function, it can also be used to develop
hazard functions. These hazard
functions, if developed using the same
model, can be summed to find the joint
hazard of several different types of
exposure (SC-83), This would allow
estimation of the total hazard from
multiple organ exposures to different
types of radiation.
As mentioned earlier, the human
median lethal dose is commonly
reported in terms of the LD50/60. Most
laboratory animal median lethal doses
are reported in terms of the LD50/30. In
those cases where estimates of both
LD50/30 and LD50/60 are available, i.e.,
B-6
-------
the burro (ST-69), the variation (that
is, the slope of the dose-response curve)
is greater in the LD50/SO study than in
the LD50/30 study. Both the dog and the
monkey data are for LD50/80, and so are
not appropriate for direct comparison
to man.
If an estimate of the deviation is
made for data from other studies and
species, those where most of the
fatalities occur within 30 days (like
dogs and monkeys) have standard
deviations of from around 20 percent
[swine (x-ray) (ST-69), dogs (NA-66),
hamsters (AI-65), primates (Maeaca)
(DA-65)] to 30 percent [swine (60Co)
(HO-68)]. Those in which most deaths
occur in 60 days, like man, have
deviations from around 20 percent
[sheep (CH-64)] to 40 percent [goats
(PA-68b), burros (TA-71)]. Nachtwey,
et al. (NA-66) suggested the steepness
of the slope of the exposure response
curve depends on the inherent
variability of the subjects exposed and
any variation induced by uncontrolled
factors, e.g., temperature, diurnal
rhythm, and state of stimulation or
arousal. So, while the slope of the
response curve for the patients studied
by the NASA panel may be
unrealistieally shallow for normal
human populations, there is no reason
to think it should be as steep as those
for dogs and monkeys.
The average deviation for those
species (burros, sheep, and goats) for
which the standard deviation of the
LD50/6o is available has been used as an
estimator for man. The mean value is
34 +. 13 percent. This is only slightly
greater than the average value for all
physically large animals (swine, burros,
sheep, and goats), 32 + 12 percent.
B.2.1.3 Estimated Lethality vs Dose
for Man
As noted in Section B.2.1.1,
dose-response estimates vary for a
number of reasons. Some factors
affecting estimates for humans are:
1. Age:
Studies on rats indicate the LD50 is
minimal for perinatal exposure, rises
to maximum around puberty, and
then decreases again with increasing
age (CA-68). The perinatal LD50 is
about one-third of that for the healthy
young adult rats; that for the geriatric
rat is about one-half of that for the
young adult rat.
2. Sex:
Females are slightly more sensitive
than males in most species (CA-68).
3. Health:
Animals in poor health are usually
more sensitive than healthy animals
(CA-68), unless elevated hematopoietie
activity is occurring in healthy
animals (SU-69).
While these and other factors will
affect the LD50/60 and the response
curve for man, there are no numerical
data available.
The variation in response at a
given dose level increases as the
population at risk becomes more
heterogeneous and as the length of
time over which mortality is expressed
B-7
-------
increases. In general, larger species
show greater variance and longer
periods of expression than do small
mammals, e.g., rodents. It is likely
that the human population would show
at least the same amount of variation
as do the larger animals, i.e., a
coefficient of variation of about
one-third.
The degree of variation exhibited
in animal studies follows a Gaussian
distribution as well as or better than a
log normal distribution over that range
of mortality where there are reasonable
statistics. We have assumed here that
the functional form of human response
is Gaussian. Generally, sample sizes
for extreme values (the upper and
lower tails of the distribution) are too
small to give meaningful results.
Therefore, we have not projected risks
for doses more than two standard
deviations from the LD60/60. We
recognize that estimates of acute
effects may not be reliable even beyond
one standard deviation for a population
containing persons of all ages and
states of health. However, in spite of
these uncertainties, previous estimates
have been made of the acute effects
caused by total body exposure to
ionizing radiation as a function of the
magnitude of the exposure (NC-71;
LtJ-68; FA-73; NA-78).
Given the large uncertainties in
the available data, a median lethal
dose value of about 300 rad at the
midline, with a standard deviation of
100 rad, may be assumed for planning
purposes. Such risk estimates should
be assumed to apply only in the
interval from 5 percent to 95 percent
fatality, as shown in Figure B-l. (See
also section B.2.1.4.)
Figure B-l is based on the
following values:
Dose (rad) Percent fatalities
<140
140
200
300
400
460
none
5
15
50
85
95
For moderately severe prodromal
(forewarning) effects, we believe the
dose at which the same percentage of
exposed would show effects would be
approximately half of that causing
fatality. This yields the following
results (see also Figure B-l):
Dose (rad) Percent affected
50
100
150
200
250
<2
15
50
85
98
Although some incidence of
prodromal effects has been observed at
doses in the range of 15 to 20 rads in
patients (LXJ-68) and in the 0 to
10 rads range of dose in Japanese
A-bomb survivors (SU-80a; GI-84),
2The risk of fatality below 140 rad is not
necessarily zero; rather, it is indeterminate and
likely to remain so. This also applies to
prodromal effects below 50 rad.
B-8
-------
100
100 200 300 400 500
WHOLE BODY ABSORBED DOSE (rad)
600
FIGURE B-1. ACUTE HEALTH EFFECTS AS A FUNCTION
OF WHOLE BODY DOSE.
B-9
-------
there is great uncertainty in
interpreting the data. Patients may be
abnormally sensitive, so that the
dose-response function in patients may
represent the lower bound of doses that
would show a response in a healthy
population (LIT-67). The response of
Japanese survivors in the low dose
ranges is complicated by the blast and
thermal exposure that occurred at the
same time (SU-80b). For these
reasons, care should be taken in
applying estimates of prodromal
effects. The prodomal dose-response
function listed above is more likely to
overestimate the proportion of persons
affected than to underestimate it.
These estimated ranges and effects
are in agreement with estimates made
for manned space flights (LA-67;
LTJ-67), which included consideration of
the effect of abnormal physiology or
sickness in the patients to which the
data apply. Uncertainty in estimates
of the biological effects of radiation
exposure is great. It is probably due in
part to variation in the health of
individuals in exposed populations.
These estimates assume a healthy
young adult population and may not be
a conservative estimate of risk for
other population groups, such as
children or the elderly. Lushbaugh,
et al. (LU-68) found that prodromal
effects probably occur in both healthy
and ill persons in about the same dose
range. However, Lushbaugh, et al.
(LU-68) and NATO (NA-73) suggest
that acute mortality in a population
which is ill, injured, or in other ways
debilitated will occur in 50 percent of
that population at doses of 200-250 rad
in about 60 days (LD50/60), in contrast to
an LD50/60 from doses of 220-310 rad for
a healthy young adult population.
Thus, the ill or injured are assumed to
have an increased risk of acute
mortality at high doses.
The above estimates for LD50/60 are
also based on the assumption of
minimal medical care following
exposure. UNSC1AR (UN-88)
estimates that the threshold for
mortality would be about 50 percent
higher in the presence of more intense
medical care.
B.2.1.4 Threshold Dose Levels for
Acute Effects
This section summarizes
information available in the literature
regarding thresholds for health effects.
It also reviews actions that have been
taken as a result of radiation exposure
to provide insight on dose levels at
which actions to avoid dose may be
appropriate.
Some acute effects, such as cellular
changes, may occur at low doses with
no dose threshold. Most such effects
have a minimum threshold of
detectability; for example, five rad is
about the lower limit of whole body
dose which causes a cellular effect
detectable by chromosome or other
special analyses (NC-71; FA-73). This
value is recommended by UNSCEAR as
the starting point for biological
dosimetry (UN-69). Purrott, et al. have
reported a lower limit of detection of
chromosome aberrations of 4 rad for
x-rays and 10 rad for gamma rays
(PU-75).
B-10
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More recent advanced chromosome
banding techniques permit detection of
increased incidence of chromosome
abnormalities from continuous
exposure to systematically deposited
radioisotopes or radioisotopes deposited
in the lung at very low levels, e.g., body
burdens of 100 to 1200 pCi of
plutonium-239 (BR-77). While the
exact dose associated with such
burdens is not known, it is probably on
the order of 10 to 100 millirem per
year. Lymphocytes exposed to 5 rem in
vitro show severe metabolic dysfunction
and interphase cell death (ST-64). The
extent to which similar effects occur
after in vivo exposure is unknown.
While chromosome abnormalities in
circulating lymphocytes are reported to
persist for long periods (UN-69), the
significance of such abnormalities is
not known (BR-77).
Hug has suggested 5 rem as the
lower limit of exposure which might
produce acute effects (WH-65). Five
rad is also in the low dose, short-term
exposure range defined by CronMte
and Haley, and is below the 10 rad
which they thought would cause only a
slight detectable physiological effect of
unknown clinical significance (CR-71).
Although the ICRP has suggested
that annual doses of 15 rad would not
impair the fertility of normal fertile
men (IC-69), an acute dose of 15 rad
causes "moderate" oligospermia
(approximately 70 percent reduction in
sperm count) which lasts for some
months (LA-67). Popescu and
Lancranjan reported alterations of
spermatogenesis and impaired fertility
in men exposed to from 500 millirad to
3 rad per year for periods varying from
2 to 22 years (PO-75). The shortest
exposure period in which abnormal
spermatogenesis was reported was 31
to 41 months (PO-75); at the highest
dose rate reported (3 rad/a), this is a
cumulative dose of 8 to 10 rem. While
more study is required, these results
suggest the need to restrict acute doses
to below 10 rem to avoid this effect,
because a given acute dose is
anticipated to be more effective than
the same cumulative dose given over a
longer period of time (NA-56; UN-58).
Many observations have indicated
that doses of 10 rem or more to the
pregnant woman are hazardous to the
fetus. Mental retardation due to
exposure of the fetus is discussed in
Section B.3; this discussion is restricted
to acute effects. The World Health
Organization (WHO) indicates that
there is no evidence of teratogenic
effects from short term exposure of the
fetus to a dose than 10 rad during
the early phase of gestation, the period
when the fetus is most sensitive to
these effects (WH-84).
A number of authorities have
recommended that exposures of 10
roentgens or higher be considered as an
indication for carrying out induced
abortion (HA-59, DE-70, BR-72,
NE-76). Brent and Gorson also suggest
that 10 rad is a "practical" threshold
for induction of fetal abnormalities
(BR-72). The Swedish Government
Committee on Urban Siting of Nuclear
Power Stations stated the situation as
follows: "What we have called
unconditional indication of abortion
involves the exposure of pregnant
B-ll
-------
women where radiation dose to the
fetus is higher than 10 rad. When
such doses are received in connection
with medical treatment, it has hitherto
been assumed that the probability of
damage to the fetus is so high that an
abortion is recommended. The
probability for such injury is still
moderate compared with the normal
frequency of similar fetal injuries, and
the probability is particularly reduced
when the dose is received late in the
pregnancy" (NA-74),
B.2.1.5 Acute Effects in the Thyroid
Acute effects are produced in the
thyroid by doses from radioiodine on
the order of 3,000 to 100,000 rad.
Ablation of the thyroid requires doses
of 100,000 rad (BE-68). The thyroid
can be rendered hypothyroid by doses
of about 3,000 to 10,000 rad (IC-71). A
thyroid dose from radioiodines of 1000
rad in adults and 400 rad in children
implies an associated whole body dose
of about 1 rad due to radioiodines
circulating in the blood. Following
inhalation of 131I, the committed
thyroid dose is about one rad/uCi
intake of ml in adults. In the
developing fetus, the thyroid dose
ranges from one to six rad per uCi of
131I entering the mother's body (IL-74).
Although acute clinical effects are
only observed at high doses, subcHnical
acute thyroid radiation effects may
occur at lower doses (DO-72). Impaired
thyroid capability may occur above a
threshold of about 200 rad (DO-72).
Effects of radiation exposure of the
thyroid have been shown in animal
experiments. Walinder and Sjoden
found that doses in excess of 3,000 rad
from 13II caused noticeable depression
of fetal and juvenile mouse thyroid
development (WA-69). Moore and
Calvin, working with the Chinese
hamster, showed that an exposure as
low as 10 roentgens (x-rays) would give
rise to 3 percent aberrant cells when
the thyroid was cultured (MO-68).
While the direct relationship of these
results to human effects is not certain,
mammalian thyroid cells can be injured
at exposures as low as 10 roentgens.
B.2.1.6 Acute Effects in the Skin
The first stage of skin reaction to
radiation exposure is erythema
(reddening) with a threshold of from
300 to 800 rad. Acute exudative
radiodermatitis results from doses of
1,200 to 2,000 rad (WH-84).
B.2.1.7
Effects
Clinical Pathophysiological
A large amount of anecdotal
information is available on the injury
of organ tissues by high doses of
radiation. Acute injury to tissue
includes swelling and vacuolation of
the cells which make up the blood
vessels, increased permeability of
vessels to fluids so that exudates form,
formation of fibrin clots and thrombi,
fibrinoid thickening in the walls of
blood vessels, and swelling and
vacuolization of parenchyma! cells. In
summary, there is an initial exudative
B-12
-------
reaction followed in time by fibrosis
and sclerosis (WH-76, CA-76).
Estimates of radiation doses
necessary to cause severe tissue
response in various organs are given in
Table B-l. These tissue dose estimates
are based on response to radiotherapy
treatment, which is normally given on
a fractionated dose basis, but also may
be given as a continuous exposure.
Therefore, these estimates must be
adjusted to the equivalent single
radiation dose for use in the present
analysis. The formalism of Kirk, et al.
(KI-71) is used to estimate the
equivalent dose for a single acute
exposure in rad-equivalent therapy
units (rets: the dose calculated from
the fractionated exposure which is
equivalent to a single acute exposure
for a specific biological endpoint.)
Table B-2 lists acute exposure
equivalents in rets for various organs.
With the exception of bone marrow,
the exposures required to cause
5 percent injury within 5 years (TD
5/5) in internal organs are in the range
of 1,000 to 5,000 rad. Since, with this
type of injury, the dose response is
nonlinear and has a threshold (i.e., is
nonstochastic), there is an exposure
below which injury is not expected. If
the shape of the injury dose-response
curve is the same for all internal
organs as it is for the lung, plotting the
two acute exposure equivalents (TD
50/5 and 5/5) for each organ on log
probability paper allows a crude
estimation of the number of clinical
pathophysiological effects per 1000
persons exposed as a function of dose
level. If one acute effect per 1000
persons within 5 years (TD 0.1/5) is
taken as the threshold for the initiation
of clinical pathophysiological effects in
organs other than thyroid, the
equivalent dose level for most organs is
550 rets or more; testes 440 ± 150 rets,
ovary 170 ± 70 rets, and bone marrow
165 rets.
The radiation exposure to organs in
rad units that will cause clinical
pathophysiological effects within 5
years to 0.1 percent of the exposed
population as a function of the duration
of a continuous level of exposure can
then be estimated by using Goitein's
modification of the Kirk methodology
(GO-76). This relationship is shown in
Table B-3.
Bone marrow is an organ of
particular concern because
radionuclides known to concentrate in
this organ system occur in nuclear
incidents. The acute lethality due to
the hematologie syndrome (LA-67) is
estimated to occur in the range of 200
to 1,000 rad, so that the difference is
small between exposure levels that
might cause acute lethality and
exposure levels that might cause only
"severe clinical pathophysiology," as
derived from radiotherapy data.
In summary, organ systems are not
expected to show symptoms of severe
clinical pathophysiology for projected
short-term exposure doses less than a
few hundred rad. Projected doses to
bone marrow at this high level are
relatively more serious and more likely
to result in injury than doses to other
organ systems. ,
B-13
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Table B-l Radiation Doses Causing Acute Injury to Organs (RU-72, RU-73)
Organ
Bone
marrow
Liver
Stomach
Intestine
Lung
Kidney
Brain
Spinal
cord
Heart
SMn
Fetus
Lens of
eye
Ovary
Testes
Volume or
area of
exposure3
whole
segment
whole
100 cm2
400 cm2
100 cm2
whole
100 cm2
whole
whole
10 cm
60 percent
—
whole
whole
whole
whole
Risk of injury in five years
5 percent
(rad)
250
3000
2500
4500
4500
5000
1500
3000
2000
6000
4500
4500
5500
200
500
200-300
500-1500
50 percent
(rad)
450
4000
4000
5500
5500
6500
2500
3500
2500
7000
5500
5500
7000
400
1200
625-1200
2000
Type of injury
aplasia and
pancytopenia
acute and chronic
hepatitis
ulcer, perforation,
hemorrhage
ulcer, perforation,
hemorrhage
acute and chronic
pneumonitis
acute and chronic
nephrosclerosis
infarction,
necrosis
infarction,
necrosis
pericarditis and
pancarditis
ulcers, fibrosis
death
cataracts
permanent
sterilization
permanent
sterilization
"Dose delivered in 200-rad fractions, 5 fractions/week.
— Unspecified.
B-14
-------
Table B-2 Acute Radiation Exposure as a Function of Rad Equivalent Therapy Units
(rets)
Organ
Bone marrow
Liver
Stomach
Intestine
Lung
Kidney
Brain
Spinal cord
Heart
Skin
Fetus
Lens of eye
Ovary
Testes
Volume or
area of
exposure
whole
segment
whole
100 cm2
400 cm2
100 cm2
whole
100 cm2
75 percent
whole
whole
10 cm
60 percent
__,
whole
whole
whole
whole
(sterilization)
Risk of injury
5 percent
(rets)
230
1135
1000
1465
1465
1570
720
1135
770b
875
1770
1465
1465
1665
200
355
200-430*
340-720a
in five years
50 percent
(rets) ,
340
1360
1360
1665
1665
1855
1000
1245
1000
1950
1665
1665
1950
315
620
410-875a
410-875°
aFor a 200-rad/treatment5 5 treatments/week schedule (LU-76).
Reference WA-73.
— Unspecified.
B-15
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Table B-3 Radiation Exposure to Organs Estimated to Cause Clinical
Pathophysiological Effects within 5 Years to 0,1 Percent of the
Exposed Population (GO-76)
Duration of
exposure
(days)
(acute)
1
2
4
7
30
365b
Ovary
(rad)
(170 rets)a
315
390
470
550
840
1740
Bone marrow
(rad)
(165 rets)
300
380
450
540
820
1690
Testes
(rad)
(440 rets)
810
1010
1210
1430
2190
4510
Other organs
(rad)
(550 rets)
1020
1260
1510
1790
2740
5640
The dose in rets is numerically equal to the dose in rads.
bAssuming tissue recovery can continue at the same rate as observed during 30- to 60-day
therapeutic exposure courses.
Even if severe clinical
pathophysiological effects can be
avoided, there is still a possibility of
clinical pathophysiological effects of a
less severe or transitory nature. The
1982 TMSCEAR report (UN-82)
reviewed much of the data on animals
and man. In the animal studies, there
were reports of: changes in stomach
acid secretion and stomach emptying at
50 to 130 rad; stunting in growing
animals at the rate of 3 to 5 percent
per 100 rad; degeneration of some cells
or functions in the brain at 100 rad,
particularly in growing animals;
temporary changes in weight of
hematopoietic tissues at 40 rad; and
more damage in ovaries and testes
caused by fractionated doses rather
than acute doses. Some of the effects
are transitory, others are long-lasting,
but with only minor reductions in
functional capacity.
Human data are limited and are
reported primarily in the radiotherapy
literature. The data suggest most
tissues in man are more radiation
resistant than those in animals.
However, the human hematopoietic
system shows a transient response,
reflected by decreased circulating white
cells and platelets, at about 50 rad.
Temporary sterility has been observed
after doses of 150 rad to the ovaries
and 10 rad to the testes, when given as
fractionated doses.
There is not sufficient data to
determine dose-response functions
B-16
-------
nor to describe the duration and
severity of dysfunction expected.
B.2.2 Summary and
Regarding Acute Effects
Conclusions
Based on the foregoing review of
acute health effects and other biological
effects from large doses delivered over
short periods of time, the following
whole body doses from acute exposure
provide useful reference levels for
decisionmaldng for PAGs:
50 rad - Less than 2 percent of the
exposed population would be
expected to exhibit prodromal
(forewarning) symptoms.
25 rad - Below the dose where
prodromal symptoms have
been observed.
10 rad - The dose level below which a
fetus would not be expected
to suffer teratogenesis (but
see Section B.3, Mental
Retardation.).
5 rad - The approximate minimum
level of detectability for acute
cellular effects using the most
sensitive methods. Although
these are not severe
pathophysiological effects,
they may be detrimental.
Based on the first principle to be
satisfied by PAGs (paragraph B.1.6),
which calls for avoiding acute health
effects, values of 50 rem for adults and
10 rem for fetuses appear to represent
upper bounds.
B.3 Mental Retardation
Brain damage to the unborn is a
class of injury reported in atomic bomb
survivors which does not fall into
either an acute or delayed effect
category, but exhibits elements of both.
What has been observed is a
significant, dose-related increase in the
incidence and severity of mental
retardation, microencephaly (small
head size), and microcephaly (small
brain size) in Japanese exposed to
radiation in utero during the 8th to
15th week after conception (BL-73;
MI-76). While the actual injury may be
acute, it is not identified until some
time after birth.
In an early study Mole (MO-82)
suggested that, although radiation
may not be the sole cause of these
conditions, it is prudent to treat the
phenomenon as radiation-related.
More recently, Otake and Schull
(OT-83) have concluded: (1) there is no
risk to live-born due to doses delivered
up to 8 weeks after conception, (2) most
damage occurs at the time when rapid
proliferation of neuronal elements
occurs, i.e., 8 to 15 weeks of gestational
age, (3) the dose-response function for
incidence during this period appears to
fit a linear model, (4) the risk of
occurrence is about five times greater
during the period 8-15 weeks of
gestation than in subsequent weeks,
and (5) in later stages of gestation, e.g.,
after the 15th week, a threshold for
damage may exist.
In their published reports, Otake
and Schull (OT-83) evaluated the
incidence of severe mental retardation
B-17
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using the T-65 dosimetry and the
dosimetry estimates developed in the
ongoing dose reassessment program for
the atomic bomb survivors, and using
two tissue dose models. Their
estimated ranges of risk were:
8 to 15 weeks after gestation:
3-4X10"3 cases/rad;
16 or more weeks after gestation:
5-VxlO"4 cases/rad.
The higher values are based on the
T-65 dosimetry and the Oak Ridge
National Laboratory estimate of tissue
dose. The lower values are based on
Oak Ridge National Laboratory
dosimetry and the Japanese National
Institute of Radiological Sciences
estimates of tissue dose. Later
estimates based on the dose
reassessment completed in 1986 are
consistent with these published results
(SC-87).
In view of the foregoing, the risk of
mental retardation from exposure of a
fetus in the 8th to 15th week of
pregnancy is taken to be about 4xlO"3
per rad. Because of this relatively high
risk, special consideration should be
given to protection of the fetus during
this period. The risk to a fetus exposed
after the 15th week is taken as 6xlO~4
per rad. For the cases studied (OT-84),
no increased incidence of mental
retardation was observed for exposure
during the 1st to the 7th week of
pregnancy.
Federal Radiation Protection
Guidance, adopted in 1987,
recommends that dose to occupationally
exposed pregnant women be controlled
to keep the fetal dose below 0.5 rem
over the entire term of pregnancy, and
that no dose be delivered at more than
the uniform monthly rate that would
satisfy this limit (i.e., approximately
50-60 mrem/month)(EP-87). The
NCRP has, for many years,
recommended a limit of 0.5 rem
(NC-71). ICRP recommends controlling
exposure of the fetus to less than 0.5
rem in the first 2 months to provide
appropriate protection during the
essential period of organogenesis
(IC-77).
B.4 Delayed Health Effects
This section addresses information
relevant to the second principle
(paragraph B.I.5) for establishing
PAGs, the risk of delayed health effects
in exposed individuals. The following
subsections summarize the estimated
risks of cancer and genetic effects, the
two types of delayed effects caused by
exposure to radiation.
B.4.1 Cancer
Because the effects of radiation on
human health have been more
extensively studied than the effects of
many other environmental pollutants,
it is possible to make numerical
estimates of the risk as a result of a
particular dose of radiation. Such
estimates, may, however, give an
unwarranted aura of certainty to
estimated radiation risks. Compared
to the baseline incidence of cancer and
genetic defects, radiogenic cancer and
B-18
-------
genetic defects do not occur very
frequently. Even in heavily irradiated
populations, the number of cancers and
genetic defects resulting from radiation
is known with only limited accuracy.
In addition, all members of existing
exposed populations have not been
followed for their full lifetimes, so data
on the ultimate numbers of effects is
not yet available. Moreover, when
considered in light of information
gained from experiments with animals
and from various theories of
carcinogenesis and mutagenesis, the
observed data on the effects of human
exposure are subject to a number of
interpretations. This, in turn, leads to
differing estimates of radiation risks by
individual scientists and expert groups.
In summary, the estimation of
radiation risks is not a fully mature
science and the evaluation of radiation
hazards will continue to change as
additional information becomes
available.
Most of the observations of
radiation-induced carcinogenesis in
humans are on groups exposed to
low-LET radiations. These groups
include the Japanese A-bomb survivors
and medical patients treated with
x-rays for ankylosing spondylitis in
England from 1935 to 1954 (SM-78).
The National Academy of Science
Committee on the Biological Effects of
Ionizing Radiations (BEIR) (NA-80)
and UNSCEAR (UN-77) have provided
knowledgeable and exhaustive reviews
of these and other data on the
carcinogenic effects of human
exposures. The most recent of the
BEIR studies was published in 1980
and is; here designated BEIR-3 to
distinguish it from previous reports of
the BEIR committee.
The most important epidemiologieal
data on radiogenic cancer is that from
the A-bomb survivors. The Japanese
A-bomb survivors have been studied for
more than 40 years, and most of them
have been followed in a major, carefully
planned and monitored epidemiologieal
survey, the Life Span Study Sample,
since (KA-82, WA-83). They were
exposed to a wide range of doses and
are the largest group that has been
studied. They are virtually the only
group providing extensive information
on the response pattern at various
levels of exposure to low-LET radiation.
The estimated cancer risk from
low-LET, whole body, lifetime exposure
presented here is based on a life table
analysis using a linear response model.
We use the arithmetic average of
relative and absolute risk projections
(the BEIR-3 L-L model) for solid
cancers, and an absolute risk projection
for leukemia and bone cancer (the
BEIR-3 L-L model). For whole body
dose, this yields an estimated 280 (with
a possible range of 120 to 1200)
fatalities per million person-rem for a
population cohort representative of the
1970 U.S. population. We assume this
estimate also applies to high-LET
radiation (e.g. alpha emitters); no
reduction has been applied for dose
rate. (The rounded value, 3xlO"4
fatalities8 per person-rem, has been
selected for this analysis.)
Preliminary reviews of new results from
studies of populations exposed at Hiroshima
B-19
-------
Whole body dose means a uniform
dose to every organ in the body. In
practice, such exposure situations
seldom occur, particularly for ingested
or inhaled radioactivity. Inhaled
radioactive particulate materials may
be either soluble or insoluble. Soluble
particulate materials deposited in the
lung will be rapidly absorbed, and the
radionuclides associated with them
distributed throughout the body by the
bloodstream. As these radionuclides
are transported in the blood, they
irradiate the entire body. Usually,
they then redeposit in one or more
organs, causing increased irradiation of
that organ. Insoluble particulate
materials, on the other hand, are only
partially absorbed into body fluids.
(This fraction is typically assumed to
be about 8 percent.) This absorption
occurs over a period of years, with a
portion entering the bloodstream and
another retained in the pulmonary
lymph nodes. The balance (92 percent)
of inhaled insoluble particulate
materials are removed from the lung
within a few days by passing up the air
passages to the pharynx where they
are swallowed. Inhaled insoluble
particulate materials thus irradiate
both the lung and the gastrointestinal
tract, with a small fraction being
eventually absorbed into the
(footnote continued)
and Nagasaki indicate that these risk
estimates may be revised upwards significantly
in the near future, particularly for acute
exposure situations. EPA has recently used a
slightly higher value, 4 x 10"4 fatalities in
standards for air emissions under the Clean
Air Act. We will revise these risk estimates to
reflect new results following appropriate
review.
bloodstream (TG-66). These
nonuniform distributions of dose (and
therefore risk) are taken into account
through use of the weighting factors for
calculating effective dose.
There is a latent period associated
with the onset of radiation-induced
cancers, so the increased risk is not
immediately apparent. The increased
risk is assumed to commence 2 to 10
years after the time of exposure and
continue the remainder of the exposed
individual's lifespan (NA-80).
For uniform exposure of the whole
body, about 50 percent of
radiation-induced cancers in women
and about 65 percent in men are fatal
(NA-80). Therefore, 1 rem of low-LET
radiation would be expected to cause a
total of about 500 cancer cases if
delivered to a population of one million.
(In the case of thyroid and skin, the
ratio of nonfatal to fatal cancers are
much higher. These are addressed
separately below.) This corresponds to
an average annual individual
probability of developing cancer of
about 7xlO"6 per year. For perspective,
the average annual risk of dying of
cancer from all causes in the United
States, in 1982, was 1.9xlQ-3.
B.4.1.1 Cancer Risk Due to Radiation
Exposure of the Thyroid
Exposure of the thyroid to
extremely high levels of radiation may
cause it to degenerate. At moderate
levels of exposure some loss of thyroid
function will occur. At lower levels of
exposure, there are delayed health
B-20
-------
effects, which take the form of both
thyroid nodules and thyroid
malignancies (NA-72; NA-80). Doses
as low as 14 rad to the thyroid have
been associated with thyroid
malignancy in the Marshall Islanders
(CO-70), The increased risk of
radiation-induced cancer is assumed to
commence about 10 years after initial
exposure and to continue for the
remaining lifespan of an exposed
individual.
The true nature of thyroid nodules
cannot be established until they are
surgically removed and examined
histologically, and those that are
malignant can lead to death if not
surgically removed (SA-68; DE-73;
PA-74). Although thyroid malignancies
are not necessarily fatal, effects
requiring surgical removal of the
thyroid cannot be considered benign.
In this analysis, all thyroid cancers,
both fatal and nonfatal, are counted for
the purpose of estimating the severity
of thyroid exposures.
Based on findings in BEIR-3, we
estimate that 1 rem of thyroid exposure
carries a risk of producing a thyroid
cancer of 3.6xlO"4, of which a small
fraction (on the order of 1 in 10) will be
fatal (NA-80). Since the calculation of
effective dose equivalent does not
include consideration of nonfatal
thyroid cancers and the severity of the
medical procedures for their cure, it is
appropriate to limit the dose to the
thyroid by an additional factor beyond
that provided by the PAG expressed in
terms of effective dose equivalent.
Protective action to limit dose to
thyroid is therefore recommended at a
thyroid dose 5 times the numerical
value of the PAG for effective dose.
B.4.1.2 Cancer Bisk Due to Radiation
Exposure of the Skin
The risk of fatal skin cancer is
estimated to be on the order of one
percent of the total risk of fatal cancer
for uniform irradiation of the entire
body (IC-78). However, since the
weighting scheme for calculating
effective dose equivalent does not
include skin, the PAG expressed in
terms of effective dose does not provide
protection against radionuclides which
primarily expose skin. As in the case
of the thyroid, the ratio of nonfatal to
fatal cancers from irradiation of the
skin is high (on the order of 100 to 1).
It would not be appropriate to ignore
this high incidence of nonfatal skin
cancers by allowing 100 times as much
dose to the skin as to the whole body.
For this reason, evacuation is
recommended at a skin dose 50 times
the numerical value of the PAG for
effective dose.
B.4.1,3 Cancer Risk Due to Radiation
Exposure of the Fetus
The fetus is estimated to be 5 to 10
times as sensitive to radiogenic cancer
as an adult (FA-73; WH-65). Stewart
reports increased relative incidence of
childhood cancers following prenatal
x-ray doses as low as 0.20 to 0.25 rem
and doubling of childhood cancers
between 1-4 rem (ST-73). She
concluded that the fetus is about
equally sensitive to cancer induction in
B-21
-------
each trimester. Her findings are
supported by similar results reported
by MacMahon and Hutchinson
(MA-64), Kaplan (KA-58), Polhemus
and Kock (PO-59), MacMahon (MA-63),
Ford, et al. (FO-59), Stewart and
Kneale (ST-70b), and an AEG report
(AE-61). MacMahon reported that
although there were both positive and
negative findings, the combination of
weighted data indicates a 40 percent
increase in childhood cancer mortality
after in vivo exposure to diagnostic x
rays (1.0 to 5.0 rad): about 1 cancer
per 2,000 exposed children in the first
10 years after birth (MA-63). He
concluded that although the range of
dose within which these effects are
observed is wide, effects will be fewer
at 1 rad than at 5 rad.
Graham, et al., investigating
diagnostic x-ray exposure, found a
significantly increased relative risk of
leukemia in children: by a factor of 1.6
following preconception irradiation of
mothers or in utero exposure of the
fetus; by a factor of 2 following
postnatal irradiation of the children;
and by a factor of 2 following
preconception irradiation of the mother
and in utero exposure of the child
(GR-66).
B.4.1.4 Age Dependence of Doses
Almost all dose models are based on
ICRP "Reference Man," which adopts
the characteristics of male and female
adults of working age. ICRP-30
dosimetric models, which use
"Reference Man" as a basis, are
therefore appropriate for only adult
workers and do not take into account
differences in dose resulting from the
differences in physiological parameters
between children and adults, e.g.,
intake rates, metabolism, and organ
size. Although it is difficult to
generalize for all radionuclides, in some
cases these differences tend to
counterbalance each other. For
example, the ratio of volume of air
breathed per unit time to lung mass is
relatively constant with age, so that
the ICRP adult model for inhaled
materials provides a reasonably good
estimate of the dose from a given air
concentration of radioactive material
throughout life.
The thyroid is an exception because
the very young have a relatively high
uptake of radioiodine into a gland that
is much smaller than the adult thyroid
(see Section B.4.2.2.). This results in a
larger childhood dose and an increased
risk which persists throughout life. We
have examined this worst case
situation. Age-specific risk coefficients
for fatal thyroid cancer (See Table 6-8
of "Risk Assessment Methodology"
(EP-89)) are about 1.9 higher per unit
dose for persons exposed at ages 0 to 9
years than for the general population.
Age-dependent dose factors (see
NRPB-R162 (GR-85)) for inhalation of
1-131, are a factor of about 1.7 higher
for 10 year olds than for adults.
Therefore, the net risk of fatal thyroid
cancer from a given air concentration of
1-131 is estimated to be a factor of
about 3 higher for young children than
for the remainder of the population.
This difference is not considered large
enough, given the uncertainties of
exposure estimation for implementing
B-22
-------
protective actions, to warrant
establishing age-dependent PAGs.
B.4.2 Genetic Risk
An average parental dose of 1 rem
before conception has been estimated to
produce 5 to 75 significant
genetically-related disorders per million
liveborn offspring (NA-80). For this
analysis we use the geometric mean of
this range, i.e. 1.9xlO"5. This estimate
applies to effects in the first generation
only, as a result of dose to parents of
liveborn offspring. The sum of effects
over all generations is estimated to be
approximately twelve times greater;
that is, 2.3xlO~4. In addition, since any
radiation dose delivered after a
parent's last conception has no genetic
effect, and not all members of the
population become parents, less than
half of the entire dose in an average
population is of genetic significance.
Taking the above factors into account,
we estimate that the risk of
genetically-related disorders in all
generations is IxlO"4 per person-rem to
a typical population.
Although the overall severity of the
genetic effects included as "significant"
in the above estimates is not well
known, rough judgements can be made.
The 1980 BEIR report referred to
"....disorders and traits that cause a
serious handicap at some time during
lifetime" (NA-80). From the types of
defects reported by Stevenson (ST-59),
it can be estimated that, of all
radiation-induced genetic effects, 50
percent lead to minor to moderate
medical problems (i.e., hair or ear
anomalies, polydactyl, strabismus, etc.),
25 percent lead to severe medical
problems (i.e., congenital cataracts,
diabetes insipidus, deaf mutism, etc.),
23 percent would require extended
hospitalization (i.e., mongolism,
pernicious anemia, manic-depressive
psychoses, etc.), and 2 percent .would
die before age 20 (i.e., anencephalus,
hydrocephalus, pancreatic fibrocytic
disease, etc.).
B.4.3 Summary of Risks of Delayed
Effects
Table B-4 summarizes average
lifetime risks of delayed health effects
based on results from the above
discussion. Because of the nature of
the dose-effect relationships assumed
for delayed health effects from
radiation (linear, nonthreshold), there
is no dose value below which no risk
can be assumed to exist.
B.4.4 Risks Associated with Other
Radiation Standards
A review of radiation standards for
protection of members of the general
population from radiation shows a
range of values spanning several orders
of magnitude. This occurs because of
the variety of bases (risk, cost,
practicability of implementation, and
the situations to which they apply) that
influenced the choice of these
standards. Some source-specific
standards are relatively protective, e.g.,
the EPA standard limiting exposure of
the public from nuclear power
operations (25 mrem/y) from all path-
B-23
-------
Table B-4 Average Risk of Delayed Health Effects in a Population*
Effects per person-rem
Fatal cancers
Nonfatal cancers
Genetic disorders
Whole Body
2.8E-4b
2.4E-4b
l.OE-4
Thyroid0 Skin
3.6E-5 3.0E-6
3.2E-4 3.0E-4
(all generations)
* We assume a population with the same age distribution as that of the U.S. population in 1970.
b Kisk to the fetus is estimated to be 5 to 10 times higher.
c Risk to young children is estimated to be about two to three times as high.
ways combined corresponds to a risk
(for cancer death) of 5xlO~4 for lifetime
exposure. Similarly, regulations under
the Clean Air Act limit the dose due to
emissions of radionuclides to air alone
from all DOE and NRC facilities to
0.01 rem per year, which corresponds
to a cancer risk of 2xlO"4 for lifetime
exposure. Other guides permit much
higher risks. For example, the level at
which the EPA recommends action to
reduce exposure to indoor radon (0.02
working levels) corresponds to a risk of
about 2xlO"2 (for fatal lung cancer) for
lifetime exposure. All of these
standards and guides apply to
nonemergency situations and were
based on considerations beyond a
simple judgement of acceptable risk.
Federal Radiation Protection
Guidance for nonemergency situations
recommends that the dose from all
sources combined (except from
exposure to medical and natural
background radiation) to individuals in
the population not exceed 0.5 rem in a
single year (FR-60) and that the dose
to the fetus of occupationally-exposed
mothers not exceed 0.5 rem during the
9-month gestation period (EP-87). This
dose corresponds to an annual
incremental risk of fatal cancer to
members of the general population of
about 1.4xlO"4. If exposure of the fetus
is limited to one ninth of 0.5 rem per
month over a 9-month gestation period,
as recommended, the risk of severe
mental retardation in liveborn is
limited to about 7xlO"4.
The International Commission on
Radiation Protection recommends that
the dose to members of the public not
exceed 0.5 rem per year due to
nonrecurring exposure to all sources of
radiation combined, other than natural
sources or beneficial medical uses of
B-24
-------
radiation (IC-77). They also
recommend a limiting dose to members
of the public of 0.1 rem per year from
all such sources combined for chronic
(i.e., planned) exposure (IC-84a), These
upper bounds may be taken as
representative of acceptable values for
the situations to which they apply.
That is, these are upper bounds of
individual risk that are acceptable for
the sum of all sources and exposure
pathways under international
recommendations, for circumstances
that are justified on the basis of public
benefit, and when actual doses from
individual sources are "as low as
reasonably achievable" (ALARA) within
these upper bounds.
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B-30
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APPENDIX C
Protective Action Guides for the Early Phase:
Supporting Information
-------
Page Intentionally Blank
-------
Contents
Page
C.I Introduction C-l
C.I.I Existing Federal Guidance C-l
C.1.2 Principal Exposure Pathways C-2
C.2 Practicality of Implementation C-3
C.2.1 Cost of Evacuation C-3
C.2.1.1 Cost Assumptions C-4
C.2.1.2 Analysis C-5
C.2.1.3 Conclusions C-10
C.2.2 Risk of Evacuation C-10
C.2.3 Thyroid Blocking C-13
C.2.4 Sheltering C-14
C.3 Recommended PAGs for Exposure to a Plume during the
Early Phase C-17
C.4 Comparison to Previous PAGs C-21
C.5 Dose Limits for Workers Performing Emergency Services C-22
References C-24
Figures
C-l Evacuation Model C-6
Tables
C-l Costs for Implementing Various PAGs for an SST-2 Type
Accident (Stability Class A) C-7
111
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Tables (continued)
Page
C-2 Costs for Implementing Various PAGs for an SST-2 Type
Accident (Stability Class C) C-8
C-3 Costs for Implementing Various PAGs for an SST-2 Type
Accident (Stability Class F) . C-9
C-4 Upper Bounds on Dose for Evacuation, Based on the Cost
of Avoiding Fatalities C-ll
C-5 Average Dose Avoided per Evacuated Individual for
Incremental Dose Levels for Evacuation C-12
C-6 Representative Dose Reduction Factors for External
Radiation , C-14
C-7 Dose Reduction Factors for Sheltering from Inhalation
of Beta-Gamma Emitters C-16
C-8 Summary of Considerations for Selecting the
Evacuation PAGs C-18
C-9 Comparison of Projected Doses for Various Reactor
Accident Scenarios C-21
C-10 Cancer Risk to Emergency Workers Receiving 25 Rem Whole
Body Dose C-24
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APPENDIX C
Protective Action Guides for the Early Phase:
Supporting Information
C.I Introduction
This appendix sets forth supporting
information for the choice of Protective
Action Guides (PAGs) for the early
phase of the response to a nuclear
incident involving the release of
airborne radioactive material. It then
describes application of the basic
principles for selection of response
levels set forth in Chapter 1 to the
guidance on evacuation and sheltering
in Chapters 2 and 5.
Response to a radiological
emergency will normally be carried out
in three phases, as discussed in
Chapter I. Decisions during the first
(early) phase will usually be based on
predicted or potential radiological
conditions in the environment, rather
than on actual measurements. The
principal protective action is
evacuation, with sheltering serving as
a suitable alternative under some
conditions. This appendix examines
the potential magnitudes and
consequences of predicted exposures of
populations during the early phase, for
selected nuclear reactor accident
scenarios, in relation to the benefits
and detrimental consequences of
evacuation and sheltering. Nuclear
reactor facilities are chosen for
evaluation because, due to their
number, size of source, and energy
available to drive a release, they are
most likely to provide an upper bound
on the magnitude of the variety of
possible sources of nuclear incidents.
Although atmospheric releases from
other types of nuclear incidents are
likely to involve smaller consequences,
the affected populations, and therefore
the costs and benefits of protective
action are each expected to scale in
roughly the same proportion for lesser
magnitude incidents. Thus, basic
conclusions developed for responses to
reactor facilities are assumed to remain
valid for other types of nuclear
incidents. Supplementary protective
actions, such as washing and change of
clothing to reduce exposure of the skin
and use of stable iodine to reduce
uptake of radioiodme to the thyroid,
are also considered, but in less detail.
C.l.l Existing Federal Guidance
In the 1960's, the Federal Radiation
Council (FRC) defined PAGs and
established limiting guides for
ingestion of strontium-89,
strontium-90, cesium-137, and
iodine-131 (FR-64; FR-65). That
guidance applied to restricting the use
of food products that had become
contaminated as the result of release of
radioactivity to the stratosphere from
weapons testing. During the period
immediately following an incident at
any domestic nuclear facility, when the
C-l
-------
critical source of exposure is expected
to be a nearby airborne plume, the
principal protective actions are
evacuation or sheltering. The PAGs
developed here thus do not supersede
previous guidance, but provide
additional guidance for prompt
exposure pathways specific to a
domestic nuclear incident.
C.1.2 Principal Exposure Pathways
The immediate exposure pathway
from a sub-stratospheric airborne
release of radioactive materials is
direct exposure from the cloud of
radioactive material carried by
prevailing winds. Such a plume can
contain radioactive noble gases,
iodines, and/or particulate materials,
depending on the source involved and
conditions of the incident. These
materials emit gamma rays, which are
not significantly absorbed by air, and
will expose the entire bodies of nearby
individuals.
Another immediate exposure
pathway occurs when people are
submerged in the cloud of radioactive
materials. In this case radioactive
materials are inhaled, and the skin and
clothes may be contaminated. Inhaled
radioactive materials, depending on
their solubility in body fluids, may
either remain in the lungs or move via
the blood to other organs. Many
radionuclides which enter the
bloodstream tend to be predominantly
concentrated in a single organ. For
example, if radioiodines are inhaled, a
significant fraction will tend to move
rapidly from the lungs through the
bloodstream to the thyroid gland where
much of the iodine will be deposited
and most of the dose1 will be delivered.
Although dose to skin from materials
deposited on the skin and clothing
could be significant, it will be less
important in terms of risk of fatal
cancer than dose from inhalation, if
early protective actions include
washing of exposed skin and changes of
clothing.
As the plume passes over an area,
radioactive materials may settle onto
the ground and other surfaces. People
remaining in the area will then
continue to be exposed through
ingestion and external radiation, and
through inhalation of resuspended
materials. The total dose from such
deposited materials may be more
significant than that due to direct
exposure to the plume, because the
term of exposure can be much longer.
However, since the protective actions
considered here (evacuation and/or
sheltering) may not be appropriate or
may not apply for this longer term
exposure, doses from these exposures
beyond the early phase are not
included in the dose considered in the
PAGs for the early phase. It is
assumed that, within four days after
an incident, the population will be
*In this and all subsequent references, the
word "dose" means the committed dose
equivalent to the specified organ, or, if no
organ is specified, the sum of the committed
effective dose equivalent from intake of
radionuclides and tike effective dose equivalent
from external sources of radiation. (Section
B.1.1 contains a more detailed discussion of
units of dose for PAGs.)
C-2
-------
protected from these subsequent doses
on the basis of the PAGs for relocation
and for contaminated food and water.
(See Chapters 3 and 4.)
Based on the foregoing
considerations, the PAGs for the early
phase are expressed in terms of
estimated doses from exposure due to
external radiation, inhalation, and
contamination of the skin only during
the early phase following an incident.
C.2 Practicality of Implementation
Whereas Appendix B deals with the
risk associated with the projected dose
that could be avoided by any protective
action, this section addresses the costs
and risks associated with evacuation
itself. That is, these analyses relate to
Principles 3 and 4 for deriving PAGs,
set forth in Chapter 1, which address
the practicality of protective actions,
rather than acceptability of risks under
Principles 1 and 2, which is evaluated
in Appendix B.
The principal relevant protective
actions during the early phase are, as
noted earlier, evacuation and
sheltering. In some cases, washing and
changing of clothing, or thyroid
blocking may also be appropriate
actions. The costs, risks, and degrees
of protection associated with
evacuation are generally higher than
those for sheltering. Although there
may be some costs and risks associated
with the other protective actions, they
are small and not readily quantifiable.
Therefore, only the costs and risks
associated with evacuation will be
evaluated here. These factors are
evaluated to determine whether the
costs are low enough to justify lower
PAGs than would be required to satisfy
upper bounds of acceptable risk under
Principles 1 and 2.
C.2.1 Cost of Evacuation
Costs incurred to reduce the
radiation risk from nuclear incidents
can be considered to fall into several
major categories. The first category
includes the design, construction, and
operation of nuclear facilities in such a
manner as to minimize the probability
and consequences of radiological
incidents. It is recognized that the
probability and consequences of such
incidents usually cannot be reduced to
zero. Therefore, a second category is
necessary: the development of
emergency response plans to invoke
actions which would reduce exposure of
potentially exposed populations, and
consequently their risks, if a major
nuclear incident should occur.
Both of the above categories of cost
are properly attributed to the cost of
design and operation of a nuclear
facility. A third category of costs is the
actual expenses incurred by taking
protective actions as the result of an
incident. In general, the choice of
levels for PAGs will affect only this
third category of costs. That is, all
costs in the first two categories are
assumed to be unaffected by decisions
on the levels of PAGs. (This will be the
case unless the PAGs were to be set so
high as to never require protective
action, in which case response plans
C-3
-------
would be unnecessary.) Therefore, the
costs associated with implementing the
PAGs are evaluated only in terms of
the actual cost of response. In a
similar manner, the risk incurred by
protective actions is compared only to
the risk associated with the radiation
dose that would be avoided by the
action, and is unaffected by any other
measures taken to reduce risks that
fall in the first two categories of cost
identified above.
C.2.1.1 Cost Assumptions
The analyses in this section are
based on evaluation of the costs of
evacuation and the doses that would be
received in the absence of protective
actions for nuclear reactor incidents.
These were calculated as a function of
offsite location, meteorological
condition, and incident type (TA-87).
Dose and cost data are based on the
following assumptions:
1. Airborne releases are those
associated with fuel melt accidents at
nuclear reactor facilities followed by
containment failure.
2. Meteorological conditions range
from stable to unstable, and
windspeeds are those typical of the
stability class.
3. Plume dispersion follows a
Gaussian distribution, with a 0.01 m/s
dry deposition velocity for iodine and
particulate materials.
4. Doses are those incurred from
whole body gamma radiation from the
plume, inhalation of radioactive
material in the plume, and from four
days exposure to deposited radioactive
material.
5. Population distributions are the
average values observed around 111
nuclear power reactor plants, based on
1970 data.
6. The cost of evacuation is $185 per
person for a 4-day evacuation involving
a 100-mile round trip, with an average
of 3 persons per household. These
evacuation costs include wages and
salaries of personnel directing the
evacuation, transportation costs of
evacuees to and from the staging
location, food and shelter for the
evacuees during the evacuation period,
loss of personal and corporate income
during the evacuation period, and the
costs of any special supplies (TA-87).
The estimated costs and doses
avoided are based on the following
idealized evacuation area model (see
Figure C.I.):
1. All people within a 2-mile radius of
the incident are evacuated for all
scenarios.
2. People are also evacuated from a
downwind area bounded by equivalent
rays on either side of the center line of
the plume, which define the angular
spread (70, 90, or 180 degrees) of the
area evacuated by an arc at the
distance beyond which the evacuation
dose would not be exceeded on the
plume centerline.
C-4
-------
Figure C-l shows the relationship
between the area in which the
evacuation dose would be exceeded and
the larger area that might be
evacuated. The figure shows the plume
centered in an idealized evacuation
area.
C.2.1.2 Analysis
Evaluation of costs for evacuation
and doses to populations as a function
of the area evacuated depends on a
variety of assumptions. Three
fuel-melt accident categories, six
meteorological stability classes, and the
three evacuation area models discussed
above were examined. Detailed
assumptions and data are reported
elsewhere (EP-87a). Selected data,
including the cost per unit of collective
dose to the population Figure 0,1
(person-rem) avoided, are presented in
Tables C-l, C-2, and C-3, for three
stability classes, for the median
nuclear accident category examined
(SST-2). (SST accident categories are
described in Section E.1.2).
The data are presented for both the
total area and the incremental area
evacuated for each change in dose level
examined. When evaluating the cost
per person-rem avoided for a specific
set of circumstances, it is appropriate
to assess the ratio of the total cost to
the total dose avoided to calculate the
average cost per person-rem avoided.
However, when one is comparing the
cost versus dose avoided to make a
judgment between a variety of different
limiting dose values, it is appropriate
to compare the dose savings and costs
at the margin, since the cost of
evacuating the additional area is
incurred to avoid the incremental
collective dose. Therefore, the
appropriate quantities are the cost and
risk for the additional area evacuated.
Results of analyses on both a total and
incremental basis are presented in
Tables C-l, C-2, and C-3 for accident
category SST-2. This is the smallest
category of fuel melt accident yielding
effective dose equivalents during the
first 4 days of exposure that are
greater than 0.5 rem outside the
assumed 2-mile evacuation circle for all
stability classes. Data on costs versus
dose saved for all three accident
categories are summarized in Table C-4
in the next section.
Changes in population density
would not affect the above results,
since both cost and collective dose are
proportional to the size of the
population affected. Factors that could
affect these results are different
assumptions for cost of evacuation,
accident scenarios, and evacuation area
models. The results will be directly
proportional to different assumptions
for the cost of evacuation. Some data
on the variation with accident scenario
are presented in the next section. In
situations where different widths of
evacuation area are assumed, the
change in cost per unit dose avoided
will be approximately proportional to
the change in width in degrees. This
approximation is more accurate for the
higher stability classes (E and F).
Evacuation within a 2 mile radius
circle and a 90 degree sector in the
downwind direction is generally
considered to be adequate for release
C-5
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2 MILE RADIUS
AREA WHERE PLUME
PAGs ARE EXCEEDED
AREA EVACUATED
FIGURE C-1. EVACUATION MODEL.
C-6
-------
Table C-l
Costs for Implementing Various PAGs for an SST-2 Type Accident (Stability Class A)
Evacuation
angle
(degrees)
70
90
180
PAG
value
(rem)
0.5
1
2
5
10
OJ
1
2
5
10
0,5
1
2
5
10
Cost
(dollars)
2.83E+7
6.68E+6
1.49E+6
2.99E+5
(a)
3.63E+7
8.54E+6
1.86E+6
3.26E+5
(a)
7.16E+7
1.67E+7
3.48E+6
4.48E+5
(a)
Total Area
Dose
avoided
(person-rem)
8.97E+4
4.06E+4
1.73E+4
5.22E+3
(a)
9.29E+4
4.24E+4
1.82E+4
5.41E+3
(a)
9.33E+4
4.27E+4
1.84E+4
5.46E+3
(a)
Dollars/
person-rem
avoided
315
164
88
57
(a)
891
201
102
60
(a)
767
391
190
82
(a)
A Cost
(dollars)
2.16E+7
5.19E-I-6
1.19E+6
9.70E+4
2.78E+7
6.68E+6
1.B4E+6
1.25E4-5
5.49E^-7
1.32E+7
8.04E+6
2.47E+5
Marginal Area
A Dose
avoided
(person-rem)
4.91E+4
2.33E+4
1.211+4
2.44E+3
5.05E+4
2.42E+4
1.28E+4
2.63E+3
5.06E+4
2.43E+4
1.29E+4
2.68E+3
A Dollars/
Aperson-rem
avoided
440
223
98
40
550
276
120
47
1080
543
235
92
' The 4-day dose does not exceed the PAG outside the 2-mile radius of flie accident site.
The total cost of evacuation within this radius is 2.02E+5 dollars;, the total dose avoided
is 2.78E+3 person-rem; and the total cost per person-rem avoided is $73,
C-7
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Table C-2
Costs for Implementing Various PAGs for an SST-2 Type Accident (Stability Class C)
Evacuation
angle
(degrees)
70
90
180
PAG
value
(rem)
0.5
1
2
5
10
20
50
0.5
1
2
5
10
20
50
0.5
1
2
5
10
20
50
Cost
(dollars)
4.95E+7
L23E+7
2.46E+6
7.82E+5
3.93E+5
2.60E+5
(a)
6.35E+7
1.58E+7
3.11E+6
9.48E+5
4.47E+5
2.77E+5
(a)
1.25E+8
3.10E+7
5.95E+6
1.68E+6
6.87E+5
3.51E+5
(a)
Total Area
Dose
avoided
(person-rem)
1.13E+5
6.31E+4
3.73E+4
2.71E+4
2.101+4
1.62E+4
(a)
1.131+5
6.32E+4
3.74E+4
2.721+4
2.10E+4
1.68E+4
(a)
1.13E+5
6.32E+4
3.74E+4
2.72E+4
2.10E+4
1.63E+4
(a)
Dollars/
person-rem
avoided
439
195
66
29
19
16
(a)
564
250
83
35
21
17
(a)
1110
491
159
62
33
22
(a)
A Cost
(dollars)
3.71E+7
9.87E+6
1.68E+6
3.89E+5
1.32E+5
3.40E-I-4
4.77E+7
1.27E+7
2.16E+6
5.00E+5
1,701+5
3.40E+4
9.44E+7
2.51E+7
4.28E+6
9.90E+5
3.36E+5
6.701+4
Marginal Area
A Dose
avoided
(person-rem)
4.95E+4
2.58E+4
1.02E+4
6.15E+3
4.75E+3
2.50E+3
4.95E+4
2.58E+4
1.02E+4
6.16E+3
4.76E+3
2.50E+3
4.95E+4
2.58E+4
1.02E+4
6.16E+3
4.77E+3
2.50E+3
A Dollars/
Aperson-rem
avoided
750
382
165
63
28
10
964
491
212
81
36
14
1910
971
419
161
70
27
The 4-day dose does not exceed the PAG outside the 2-mile radius of the accident site.
The total cost of evacuation within this radius is 2.02E+5 dollars; the total dose avoided
is 2.78E+3 person-rem; and the total cost per person-rem avoided is $73.
C-8
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Table C-3
Costs for Implementing Various PAGs for an SST-2 Type Accident (Stability Class F)
Evacuation PAG
angle value
(degrees) (rem)
70 0.5
1
2
5
10
20
50
90 0.5
1
2
5
10
20
50
180 0.5
1
-• - - 2
5 •
10
20
50
Cost
(dollars)
8.95E+7
4.95E+7
2.831+7
1.23E+7
6.68E+6
3.65E+6
1.49E+6
1.15E+8
6.35E+7
3.63E+7
1.58E+7
8.54E+6
4.64E+6
1.86E+6
2J7E+8
1.25E+8
7.16E+7
3.10E+7
1.67E+7
8.981+6
3.511+6
Total Area
Dose
avoided
(person-rem)
461E+5
4.41E+5
4.19E+5
3.831+5
3.53E+5
3.22E+5
2.68E+5
4.61E+5
4.411+5
4.19E+5
3.83E+5
3.53E+5
3.22E+5
2.68E+5
4.61E+5
4.411+5
4.19E+5
3.83E+5
3.531+5
3J2E+5
2.68E+5
Dollars/
person-rem
avoided
194
112
67
32
19
11
5.6
250
144
87
41
24
14
6.9
493
285
171
81
47
28
13
A Cost
(dollars)
4.01E+7
2.12E+7
1.59E+7
5.65E+6
3.03E+6
9.70E+5
5.15E+7
2.72E+7
2.05E+7
7.26E+6
3.90E+6
1.30E+6
1.02E+8
5.39E+7 ..
4.05E+7
1.44E+7
7.71E+6
2.40E+6
Marginal Area
A Dose
avoided
(person-rem)
1.98E+4
2.17E+4
3.66E+4
2.93E+4
3.18E+4
3.101+4
1.98E+4
2.17E+4
3.66E+4
2.93E+4
3.181+4
3.10E+4
1.99E+4
. 2.17E+4
3.66E+4
2.921+4
. 3.18E+4
3.10E+4
A Dollars/
A person-rem
avoided
2020
977
436
193
95
32
2600
1260
560
248
123
41
5120
2480
1110
492
242
80
C-9
-------
durations not exceeding a few hours
and where reliable wind direction
forecasts are available.
C.2.1.3 Conclusions
As shown in. Tables C-l, C-2, and
C-3 for an SST-2 accident, the cost per
unit dose avoided is greatest for wide
angle evacuation and for the most
stable conditions, class (F). Although a
few emergency plans call for evacuation
over wider angles (up to 360 degrees),
the model shown in Figure C-l with a
90 degree angle is most common.
To estimate an upper bound on dose
for evacuation based on cost, we first
consider common values placed on
avoiding risk. As one input into its
risk management decisions, EPA has
used a range of $400,000 to $7,000,000
as an acceptable range of costs for
avoiding a statistical death from
pollutants other than radiation. For a
risk of 3xlO"4 cancer deaths per
person-rem (see Appendix B), these
dollar values are equivalent to a range
of from about $120 to $2,000 per
person-rem avoided. These values can
be compared to the marginal
cost-effectiveness (dollars per
person-rem) of evacuation over an
angle of 90 degrees. The resulting
ranges of upper bounds on dose are
shown in Table C-4 for SST-1, SST-2,
and SST-3 accident scenarios. The
maximum upper bounds (based on
minimum costs for avoiding risk) range
from 1 to 10 rem, with most values
being approximately 5 rem. The
minimum upper bounds (based on
maximum costs for avoiding risk) range
from 0.15 to 0.8 rem, with 0.5 rem
being representative of most situations.
From these data we conclude that,
based on the cost of evacuation, a PAG
larger than the range of values 0.5 to 5
rem would be incompatible with
Principle 3.
C.2.2 Risk of Evacuation
Principle 4 requires that the risk of
the protective action not exceed the
risk associated with the dose that will
be avoided. Risk from evacuation can
come from several sources, including
(1) transportation incidents for both
pedestrians and vehicle passengers, (2)
exposure to severe weather conditions
or a competing disaster, and (3), in the
case of immobile persons, anxiety,
unusual activity, and separation from
medical care or services. The first
source, transportation incidents, is the
only category for which the risk has
been quantified. An EPA report
(HA-75) evaluated the risk of
transportation fatalities associated
with emergency evacuations that have
actually occurred and concluded that
the risk of death per mile traveled is
about the same as that for routine
automobile travel. Using this as a
basis, the risk of death from travel is
about 9xlO"8 deaths per person-mile, or
9xlO"6 deaths per person for the
100-mile round trip assumed for
evacuation. Assuming a risk of fatal
cancer from radiation of approximately
3x10"* per person-rem, such an
evacuation risk is equivalent to a dose
of about 0.03 rem.
C-10
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Table C-4 Upper Bounds on Dose for Evacuation, Based on the Cost of Avoiding Fatalities8
Dose Upper Bounds'5'0
Accident
Category
SST-1
SST-2
SST-3
Atmospheric
Stability Class
A
C
F
A
C
F
A
C
F
Maximum
(rem)
5
5
10
1
3.5
10
(d)
(d)
5
, Minimum
(rem)
0.4
0.4
0.8
0.15
0.25
0.7
(d)
(d)
0.45
a Based on data from EP-87a.
b Windspeeds typical of each stability class were chosen.
c Based on an assumed range of $400,000 to $7,000,000 per life saved.
a For stability classes A and C, the dose from an SST-3 accident is not predicted to exceed 0.5 rem
outside a 2-mile radius. It is assumed that evacuation inside this radius would be carried out
based on the emergency condition on the site. No differential evacuation costs were calculated
within this area. i
In comparing this risk (or, more
exactly, its equivalent in dose) to the
risk avoided by evacuation, it is
important to note that protective action
must be implemented over a larger
population than will actually be
exposed at the level of the PAG.
Because of uncertainty or
unpredictable changes in wind
direction, the exact location of the
plume will not be precisely known.
Dose projections are made for the
maximum exposed individuals - those
at the assumed location of the plume
centerline. ^To assure that these
individuals will be protected, it is
necessary that others on either side
take protective action at exposures that
are less than at the plume centerline,
and, in some cases, are zero. Thus, the
entire evacuated population could
incur, on the average, a risk from the
protective action which exceeds the risk
of the radiation dose avoided.
Although it is not possible to assure
that no individuals incur risks from
evacuation greater than their radiation
risks, we can assure that this does not
C-ll
-------
occur, on the average, at the outer
margin of the evacuation area. For
this reason, we also examined the
average dose avoided for the
incrementally evacuated population for
various choices of evacuation levels.
Table C-5 presents the results, which
are derived from the data in Tables
C-l, C-2, and C-3. For the levels
analyzed, the average dose avoided is
always significantly greater than 0.03
rem. We conclude, therefore, that the
choice of PAGs will not be influenced
by Principle 4, for persons in the
general population whose risk from
evacuation is primarily the normal risk
of transportation, if the centerline dose
avoided is at or above 0.5 rem.
As previously discussed, hazardous
environmental conditions (e.g., severe
weather or a competing disaster) could
create transportation risks from
evacuation that would be higher than
normal. It is therefore appropriate to
make an exception to allow higher
projected doses for evacuation decisions
under these circumstances. In the
absence of any definitive information
on such higher risks from evacuation,
we have arbitrarily assumed that it
would be appropriate to increase the
Table C-5 Average Dose Avoided per Evacuated Individual for Incremental Dose
Levels for Evacuation
Centerline dose
(rem)
Average dose avoided (rem per
individual) by stability class
C
F
0.5 to 1
Ito2
2 to 5
5 to 10
0.34
0.67
0.19
0.38
0.87
0.07
0.15
0.33
0.75
recommended projected dose for
evacuation of the general population
under hazardous environmental
conditions up to a factor of 5 higher
than that used under normal
environmental conditions.
It is also recognized that those
persons who are not readily mobile are
at higher risk from evacuation than are
average members of the population. It
would be appropriate to adopt higher
PAGs for evacuation of individuals who
would be at greater risk from
evacuation itself than for the typically
healthy members of the population,
who are at low risk from evacuation.
In the absence of definitive information
C-12
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on the higher risk associated with the
evacuation of this group, we have
arbitrarily assumed that it is
appropriate to adopt PAGs a factor of
five higher for evacuation, of high risk
groups under normal environmental
conditions. If both conditions exist,
(high risk groups and hazardous
environmental conditions) projected
doses up to 10 times higher than the
PAGs for evacuation of the general
population under normal conditions
may be justified. These doses are
expected to satisfy Principle 4 without
violating Principles 1 and 3. Although
they violate Principle 2, Principle 4
becomes, for such cases, the overriding
consideration.
C.2.3 Thyroid Blocking
The ingestion of stable potassium
iodide (KI) to block the uptake of
radioiodine by the thyroid has been
identified as an effective protective
action. The Food and Drug
Administration (FDA) analyzed
available information on the risk of
radioiodine-induced thyroid cancers
and the incidence and severity of side
effects from potassium iodide (FD-82).
They concluded "...risks from the
short-term use of relatively low doses
of potassium iodide for thyroid blocking
in a radiation emergency are
outweighed by the risks of
radioiodine-induced thyroid nodules or
cancer at a projected dose to the
thyroid gland of 25 rem. FDA
recommends that potassium iodide in
doses of 130 milligrams (mg) per day
for adults and children above 1 year
and 65 mg per day for children below 1
year of age be considered for thyroid
blocking in radiation emergencies in
those persons who are likely to receive
a projected radiation dose of 25 rem or
greater to the thyroid gland from
radioiodines released into the
environment. To have the greatest
effect in decreasing the accumulation of
radioiodine in the thyroid gland, these
doses of potassium iodide should be
administered immediately before or
after exposure. If a person is exposed
to radioiodine when circumstances do
not permit the immediate
administration of potassium iodide, the
initial administration will still have
substantial benefit even if it is taken 3
or 4 hours after acute exposure".
Evacuation and sheltering are,
however, preferred alternatives for
most situations because they provide
protection for the whole body
and avoid the risk of misapplication of
potassium iodide.
The Federal Emergency
Management Agency has published a
Federal policy developed by the Federal
Radiological Preparedness Coordinating
Committee regarding the use of KI as
a protective action (FE-85). In
summary, the policy recommends the
stock-piling of KI and distribution
during emergencies to emergency
workers and institutionalized persons,
but does not recommend requiring
stockpiling or distribution to the
general public. The policy recognizes,
however, that options on the
distribution and use of KI rests with
the States and, hence, the policy
statement permits State and local
governments, within the limits of their
authority, to take measures beyond
C-13
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those recommended or required
nationally.
C.2,4 Sheltering
Sheltering means staying inside a
structure with doors and windows
closed and, generally, with exterior
ventilation systems shut off.
Sheltering in place (i.e. at or near the
location of an individual when the
incident occurs) is a low-cost, low-risk
protective action that can provide
protection with an efficiency ranging
from almost 100 percent to zero,
depending on title circumstances. It can
also be particularly useful to assure
that a population is positioned so that,
if the need arises, communication with
the population can be carried out
expeditiously. The degree of protection
provided by a structure is governed by
attenuation of radiation by structural
components (the mass of walls, ceilings,
etc.) and by its outside/inside air-
exchange rate. These two protective
characteristics are considered
separately.
The protection factor may be
characterized by a dose reduction factor
(DRF), defined as:
^ose
protective action
dose without protective action
The shielding characteristics of most
structures for gamma radiation can be
categorized based on whether they are
"small" or "large." Small structures are
primarily single-family dwellings, and
large structures include office,
industrial, and commercial buildings.
The typical attenuation factors given in
Table C-6 show the importance of the
type of structure for protection from
external gamma radiation (EP-78a). If
the structure is a wood frame house
without a basement, then sheltering
from gamma radiation would provide a
DBF of 0.9; i.e., only 10 percent of the
dose would be avoided. The DRFs
shown in Table C-6 are initial values
prior to infiltration of contaminated
air, and therefore apply only to short
duration plumes. The values will
increase with increasing time of
exposure to a plume because of the
increasing importance of inside-outside
air exchange. However, this reduction
Table C-6 Representative Dose Reduction Factors for External Radiation
Structure
DRF
Effectiveness
(percent)
Wood frame house (first floor) 0.9
Wood frame house (basement) 0.6
Masonry house 0.6
Large office or industrial building 0.2 or less
10
40
40
80 or better
C-14
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in efficiency is not dramatic for source
terms involving primarily gamma
radiation, because most of the dose
arises from outside, not from the small
volume of contaminated air inside a
shelter. Therefore, most shelters will
retain their efficiency as shields
against gamma radiation, even if the
concentration inside equals the
concentration outside.
The second factor is the
inside/outside air exchange rate. This
factor primarily affects protection
against exposure by inhalation of
airborne radionuclides with half lives
long compared to the air exchange rate.
The factor is expressed as the number
of air exchanges per hour, L (h"1), or
the volume of fresh air flowing into and
out of the structure per hour divided by
the volume of the structure. Virtually
any structure that can be used for
sheltering has some degree of
outside/inside air exchange due to
natural ventilation, forced ventilation,
or uncontrollable outside forces,
primarily wind.
Assuming constant atmospheric and
source conditions and no effects from
filtration, deposition, or radioactive
decay, the following model can be used
to estimate the buildup of indoor
concentration of radioactivity, for a
given outdoor concentration, as a
function of time after appearance of the
plume and of ventilation rate:
Q = C0(l - eLt),
where Cj = concentration inside,
C0 = concentration outside,
L = ventilation rate (h"1), and
t = elapsed time (h).
Typical values for ventilation rates
range from one-fifth to several air
exchanges per hour. In the absence of
measurements, an air exchange rate of
1.0/h may be assumed for structures
with no special preparation except for
closing the doors and windows. An, air
exchange rate of 0.3/h is appropriate
for relatively air-tight structures, such
as well-sealed residences, interior
rooms with doors chinked and no
windows, or large structures with
ventilation shut off. Using the above
model to calculate indoor concentration
relative to outdoor concentration after
one, two, and four complete air
exchanges, the indoor concentration
would be about 64 percent, 87 percent,
and 98 percent of the outside
concentration, respectively. It is
apparent that staying in a shelter for
more time than that required for one or
two complete air exchanges is not very
effective for reducing inhalation
exposure.
The inhalation DRF is equal to the
ratio of the average inside to outside
air concentration over the period of
sheltering. Studies have been
conducted of typical ventilation rates
for dwellings (EP-78a) and for large
commercial structures (GR-86). In
each case the rate varies according to
the air tightness of the structure,
windspeed, and the indoor-to-outdoor
temperature difference. For the
purpose of deriving PAGs, average
ventilation rates were chosen for the
two types of structures that are of
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greatest interest. Table C-7 shows
calculated dose reduction factors for
inhalation exposure as a function of
plume duration, for beta-gamma source
terms, assuming average ventilation
rates for these structures.
A potential problem with sheltering
is that persons may not leave the
shelter as soon as the plume passes
and, as a result, will receive exposure
from radioactive gases trapped inside.
The values for DRFs tabulated in Table
C-7 ignore this potential additional
contribution. This effect is generally
minor for gamma dose (generally less
than a 10 percent increase in the dose
received during plume passage,
(EP-78b)), but can be greater for
inhalation dose.
Doses from inhalation during
sheltering can be reduced in several
ways, including reducing air exchange
rates by sealing cracks and openings
with cloth or weather stripping, tape,
etc., and filtering the inhaled air with
commonly available items like wet
towels and handkerchiefs. Analyses for
some hypothesized accidents, such as
short-term transuranic releases, show
that sheltering in residences and other
Table C-7 Dose Reduction Factors for Sheltering from Inhalation of Beta-Gamma
Emitters
Ventilation rate
(air changes/h)
Duration of
plume exposure(h)
DRF
0.3tt 0.5
1
2
4
6
1.0b 0.5
1
2
4
6
0.07
0.14
0.25
0.41
0.54
0.21
0.36
0.56
0.75
0.83
"Applicable to relatively "airtight" structures such as well- sealed residences, interior rooms with
chinked doors and no windows, or large structures with outside ventilation shut off.
""Applicable to structures with no special preparation except for closing of doors and windows.
C-16
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buildings can be more effective than for
beta-gamma emitters, may provide
adequate protection, and may be more
effective than evacuation when
evacuation cannot be completed before
plume arrival (DO-90), However,
sheltering effectiveness for the
inhalation exposure pathway can be
reduced drastically by open windows
and doors or by forced air ventilation.
Therefore, reliance on protection
assumed to be afforded based on large
dose reduction factors for sheltering
should be accompanied by cautious
examination of possible failure
mechanisms, and, except in very
unusual circumstances, should not be
relied upon at projected doses greater
than 10 rem. Such analysis should be
based on realistic or "best estimate"
dose models and include consideration
of unavoidable dose if evacuation were
carried out.
C.3 Recommended PAGs for Exposure
to a Plume during the Early Phase
The four principles which form the
basis for the selection of PAG values
are presented in Chapter 1. The risks
of health effects from radiation that are
relevant to satisfying Principles 1 and
2 are presented in Appendix B and
analyses of the costs and risks
associated with evacuation relative to
Principles 3 and 4 have been presented
in this appendix. These results, for
application to the early phase, are
summarized in Table C-8.
The following describes how these
results lead to the selection of the
PAGs. Conformance to Principle 1
(avoidance of acute health effects) is
assured by the low risk required to
satisfy Principle 2, and thus requires
no additional consideration. Principle
2 (acceptable risk of delayed health
effects) leads to the choice of 0.5 rem as
an upper bound on the avoided dose
below which evacuation of the general
population is justified under normal
conditions. This represents a risk of
about 2E-4 of fatal cancer. Maximum
lifetime risk levels considered
acceptable by EPA from routine
operations of individual sources range
from 1E-6 to 1E-4. Bisk levels that are
higher than this must be justified on
the basis of the emergency nature of a
situation. In this case, we judge that
up to an order of magnitude higher
combined risk from all phases of an
incident may be justifiable. The choice
of 0.5 rem avoided dose as an
appropriate criterion for an acceptable
level of risk during the early phase is a
subjective judgment that includes
consideration of possible contributions
from exposure during other phases of
the incident, as well as the possibility
that risk estimates may increase
moderately in the near future as a
result of current reevaluations of
radiation risk.
Principle 4 (risk from the protective
action must be less than that from the
radiation risk avoided) supplies a lower
bound of 0.03 rem on the dose at which
evacuation of most members of the
public is justified. Finally, under
Principle 3 (cost/risk considerations)
evacuation is justified only at values
equal to or greater than 0.5 rem. This
will be limiting unless lower values are
required for purely health-based
C-17
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Table C-8 Summary of Considerations for Selecting the Evacuation PAGs.
Dose
(rem)
50
10
5
5
Consideration
Assumed threshold for acute
health effects in adults.
Assumed threshold for acute
health effects in the fetus.
Maximum acceptable dose for normal
occupational exposure of adults.
Maximum dose justified to average
Principle
1
1
2
Section
B.2.1.4
B.2.1.4
C.5
members of the population, based
on the cost of evacuation. 3 C.2.1.3
0.5 Maximum acceptable dose to the
general population from all
sources from nonrecurring, non-
accidental exposure. 2 B.4.4
0.5 Minimum dose justified to average
members of the population, based
on the cost of evacuation. 3 C.2.1.3
0.5 Maximum acceptable dosea to
the fetus from occupational
exposure of the mother. 2 C.5
0.1 Maximum acceptable dose to the
general population from all
sources from routine (chronic),
nonaccidental exposure. 2 B.4.4
0.03 Dose that carries a risk assumed
to be equal to or less than that
from evacuation. 4 C.2.2
This is also the dose to the 8- to 15-week-old fetus at which the risk of mental retardation is assumed
to be equal to the risk of fatal cancer to adults from a dose of 5 rem.
C-18
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reasons (Principle 2). But this is not
the case. The single lower purely
health-based value, 0.1 rem, is only
valid as a health-based criterion for
chronic exposure.
In summary, we have selected the
value 0.5 rem as the avoided dose
which justifies evacuation, because 1) it
limits the risk of delayed effects on
health to levels adequately protective of
public health under emergency
conditions, 2) the cost of
implementation of a lower value is not
justified, and 3) it satisfies the two
bounding requirements to avoid acute
radiation effects and to avoid
increasing risk through the protective
action itself. We note that this choice
also satisfies the criterion for
acceptable risk to the fetus of
OGCUpationally exposed mothers (as
well as falling well below dose values
at which abortion is recommended).
As noted in Section C.2.4, we
assume that the dose normally
avoidable by evacuation (the dose that
is not avoided by the assumed
alternative of sheltering) is one half of
the projected dose. The value of the
PAG for evacuation of the general
public under normal circumstances is
therefore chosen as one rem projected
sum of the committed effective dose
equivalent from inhalation of
radionuclides and effective dose
equivalent from exposure to external
radiation.
The above considerations apply to
evacuation of typical members of the
population under normal
circumstances, and apply to effective
doses (i.e. the weighted sum of doses to
all organs). As discussed in previous
sections, it may be appropriate to
further limit dose to the thyroid and
skin, to adjust the value for special
groups of the population at unusually
high risk from evacuation, and to
provide for situations in which the
general population may be at higher
than normal risk from evacuation.
These are addressed, in turn, below.
In the case of exposure of the
thyroid to radioiodine, action based
solely on effective dose would not occur
until a thyroid dose about 33 times
higher than the corresponding effective
dose to the entire body. As noted in
Section B.4.1.1, because the weighting
factor for thyroid used to calculate
effective dose does not reflect the high
ratio of curable to fatal thyroid cancers,
protective action to limit dose to the
thyroid is recommended at a thyroid
dose 5 times the numerical value of the
PAG.
Similarly, since effective dose does
not include dose to the skin, and for
other reasons discussed in Section
B.4.1.2, protective action to limit dose
to skin is recommended at a skin dose
50 times the numerical value of the
PAG. As in the case of the thyroid,
this includes consideration of the risk
of both curable and noncurable cancers.
Special risk groups include fetuses,
and persons who are not readily
mobile. As noted in Sections B.4.1.3
and B3, we assume that the risk of
radiation-induced cancer is about 5 to
10 times higher for fetuses than for
adults and that the risk of mental
C-19
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retardation in fetuses exposed during
the 8th to 15th weeks of gestation is
about 10 times higher than the risk of
fatal cancer in equivalently exposed
adults. However, due to the difficulty
of rapidly evacuating only pregnant
women in a population, and the
assumed higher-than-average risk
associated with their evacuation, it is
not considered appropriate to establish
separate PAGs for pregnant women.
We note that the PAG is chosen
sufficiently low to satisfy Federal
guidance for limiting exposure of the
fetus in pregnant workers.
Higher PAGs for situations
involving higher risks from evacuation
were discussed in Section C.2.2. Under
normal, low-risk, environmental
conditions, PAGs for evacuation of
groups who present higher than
average risks from evacuation (e.g.,
persons who are not readily mobile) are
recommended at projected doses up to
5 rem. Evacuation of the general
population under high-risk
environmental conditions is also
recommended at projected doses up to
5 rem. If evacuation of high risk
groups under hazardous environmental
conditions is being considered,
projected doses up to 10 rem may,
therefore, be justified.
Short-term sheltering is recognized
as alow-cost, low-risk, protective action
primarily suited for protection from
exposure to an airborne plume.
Sheltering will usually be clearly
justified to avoid projected doses above
0.5 rem, on the basis of avoidance of
health risks. However, data are not
available to establish a lower level at
which sheltering is no longer justified
because of its cost or the risk
associated with its implementation.
Sheltering will usually have other
benefits related to emergency
communication with members of the
public. It is expected that protective
action planners and decision
authorities will take into account the
added benefits of sheltering (e.g.,
communication and established
planning areas) for decisions on
sheltering at levels below 0.5 rem.
Bathing and changing of clothing
are effective for reducing beta dose to
the skin of persons exposed to an
airborne plume of radioactive
materials. Since these are also
low-cost, low-risk actions, no PAG is
recommended for initiating their
implementation. It is expected that
any persons exposed in areas where
evacuation is justified based on
projected dose from inhalation will be
routinely advised by emergency
response officials to take these actions
within 12 hours after exposure.
The use of stable iodine to protect
against uptake of inhaled radioiodine
by the thyroid is recognized as an
effective alternative to evacuation for
situations involving radioiodine
releases where evacuation cannot be
implemented. If procedures are
included in the applicable emergency
response plan, use of stable iodine
should be considered for any such
situation in which evacuation or
sheltering will not be effective in
preventing thyroid doses of 25 rem (see
also C.2.3).
C-20
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C.4 Comparison to Previous PAGs
This section compares the level of
protection provided by the previously
published PAGs for evacuation (one
rem external gamma dose from the
plume and 5 rem committed dose to the
thyroid from inhalation, under normal
evacuation circumstances) with this
PAG. The effective dose addressed by
this PAG, as well as skin, thyroid, and
external gamma doses from the plume
during the early phase from the three
major exposure pathways for an
airborne release were calculated for
radionuclide mixes postulated for three
nuclear power plant accident
sequences. The doses were then
normalized for each accident so that
they represent a location in the
environment where the controlling dose
would be equal to the current PAG.
These results are shown in Table C-9.
Based on the results shown in Table
C-9, the following conclusions are
Table C-9. Comparison of Projected Doses for Various Reactor Accident Scenarios8
Accident
category15
SST-1
SST-2
SST-3
Effective dose
equivalent0
(rem)
0.7
1
0.4
Skin dosed
(rem)
6
5
6
Thyroid dose6
(rem)
5
5
5
External
dosef
(rem)
0.02
0.4
0.1
aDoses are normalized to the limiting PAG.
bSee Table E-l for a description of these accident scenarios.
The dose is the sum of doses from 4-day exposure to external gamma radiation from deposited
materials, external exposure to the plume, and the committed effective dose equivalent from
inhalation of the plume.
dose equivalent from external beta radiation from the plume and from 12 hours exposure to
materials deposited on skin and clothing.
eCommitted dose equivalent to the thyroid from inhalation.
'External gamma dose equivalent from the plume.
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apparent, for the accident sequences
analyzed:
1. The PAG for the thyroid is
controlling for all three accident
categories. For the SST-2 category,
effective dose is also controlling.
Thus,application of the previous PAG
(5 rem) for thyroid would provide the
same protection as the revised PAG for
all three accident categories.
2. Skin doses will not be controlling
for any of the accident sequences (if
bathing and change of clothing is
completed within 12 hours of plume
passage, as assumed).
3. Gamma dose from direct exposure
to the plume is small compared to the
effective dose from the three major
exposure pathways combined.
In summary, for the accident
sequences analyzed, the old PAGs
provide the same level of protection as
the new PAGs. For releases that
contain a smaller fraction radioiodines
than these accident scenarios the new
PAGs are slightly more protective.
C.5 Dose Limits for Workers
Performing Emergency Services
Dose limits for workers during
emergencies are based on avoiding
acute health effects and limiting the
risk of delayed health effects, in the
context of the need to assure protection
of the population and of valuable
properties. It is assumed that most
such workers are accustomed to
accepting an element of risk as a
condition of their employment.
Examples of occupations that may be
affected include law enforcement,
firefighting, radiation protection, civil
defense, traffic control, health services,
environmental monitoring, animal care,
and transportation services. In
addition, selected workers at utility,
industrial, and at farms and other
agribusinesses may be required to
protect others, or to protect valuable
property during an emergency. The
above are examples -- not designations
-- of workers that may be exposed to
radiation during emergencies.
Radiation exposure of workers
during an emergency should normally
be governed by the Federal Radiation
Protection Guidance for Occupational
Exposure (EP-87). This guidance
specifies an upper bound of five rem
committed effective dose equivalent per
year for most workers. (Pregnant
women, who, under this guidance
should not normally engage in work
situations that involve more than
approximately 50 mrem/month, would
normally be evacuated as part of the
general population.) The guidance also
specifies that doses to workers should
be maintained as low as reasonably
achievable; that doses should be
monitored; and that workers should be
informed of the risks involved and of
basic principles for radiation
protection.
There are some emergency
situations, however, for which higher
doses may be justified. These include
lifesaving operations and the protection
of valuable property. International
guidance (IC-77) recognizes two
C-22
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additional dose levels for workers
under specially justified circumstances:
two times the annual limit for any
single event, and five times the annual
limit in a lifetime. The dose limits
recommended here adopt the former
value (10 rem) for operations limited to
the protection of valuable property.
The latter value (25 rem) may be
permitted for situations involving
lifesaving operations or activities that
are essential to preventing substantial
risks to populations. In this context
"substantial risks" means collective
doses that are significantly larger than
those incurred through the protective
activities engaged in by the workers.
Workers should not operate under dose
limits higher than five rem unless the
following conditions are satisfied:
1. Lower doses through the rotation of
workers or other commonly-used dose
reduction methods are not possible,
and
2. Instrumentation is available to
measure their exposure.
In addition to the limitation on
effective dose equivalent, the dose
equivalent received in any year by
workers under normal occupational
conditions is limited to 15 rem to the
lens of the eye and 50 rem to any other
organ, tissue (including skin), or
extremity of the body. (Extremity is
defined as the forearms and hands or
the lower legs and feet (EP-87).) By
analogy to these dose limits for organs
and extremities, the limits for workers
performing the various categories of
emergency services are established at
numerical values that are 5 times the
limits for effective dose to the lens of
the eye and 10 times the limits for
effective dose to any other organ, tissue
(including skin), or extremity of the
body.
Situations may occur in which a
dose in excess of 25 rem would be
required for lifesaving operations. It is
not possible to prejudge the risk that
one person should be allowed to take to
save the life of another. However,
persons undertaking an emergency
mission in which the dose would exceed
25 rem to the whole body should do so
only on a voluntary basis and with full
awareness of the risks involved,
including the numerical levels of dose
at which acute effects of radiation will
be incurred and numerical estimates of
the risk of delayed effects.
The risk of acute health effects is
discussed in B.2. Table C-10 presents
estimated cancer mortality rates for a
dose of 25 rem, as a function of age at
the time of exposure. The risk of
cancer from moderately higher doses
will increase proportionately. These
values were calculated using risk
estimates from BBIR-3 (NA-80) as
discussed in Section B.4, and life table
analyses that assume the period of
"cancer risk lasts for the worker's
lifetime (BU-81). The risk was
calculated for the midpoint of each age
range. Roughly equivalent risks of
nonfatal cancer and serious genetic
effects (if gonadal tissue is exposed)
will also be incurred.
The dose limits of 75 rem to the
whole body previously recommended by
EPA and 100 rem that has been
C-23
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recommended by NCRP (GL-57) for
Mfesaving action represents a very high
level of risk of acute and delayed
health effects. A dose of 100 rem is
expected to result in an approximately
15 percent risk of temporary incap-
acity from nonlethal acute effects and
an indeterminate, but less than 5
percent, chance of death within 60
days. This is in addition to a risk of
about 1 in 30 of incurring fatal cancer.
Such high risk levels can only be
accepted by a recipient who has been
made aware of the risks involved.
Therefore, no absolute dose limit for
lifesaving activities is offered.
Table C-10 Cancer Risk to Emergency Workers Receiving 25 Rem Whole Body
Dose
Age of the
emergency
worker at tame
of exposure
(years)
Approximate risk
of premature death
(deaths per 1,000
persons exposed)
Average years of
life lost if
premature death
occurs
(years)
20 to 30
30 to 40
40 to 50
50 to 60
9.1
7.2
5.3
3.5
24
19
15
11
References
BU-81 Bunger, B.M., J.R. Cook,
and M.K Barriek. Life Table Methodology
for Evaluating Radiation Risk - An
Application Based on Occupational
Exposures. Health Physics 40 (1981):439-
455.
DO-90 U.S. Department of
Energy. Effectiveness of Sheltering in
Buildings and Vehicles for Plutonium.
DOE/EH-0159, U.S. Department of Energy,
Washington (1990).
EP-78a U.S. Environmental Protection
Agency. Protective Action Evaluation Part I
- The Effectiveness of Sheltering as a
Protective Action Against Nuclear Accidents
Involving Gaseous Releases. EPA
520/1-78-001A, U.S. Environmental
Protection Agency, Washington (1978).
C-24
-------
EP-78b U.S. Environmental Protection
Agency. Protective Action Evaluation Part
II - Evacuation and Sheltering as Protective
Actions Against Nuclear Accidents
Involving Gaseous Releases. EPA
520/1-78-001B, U.S. Environmental
Protection Agency, Washington (1978).
EP-87 U.S. Environmental Protection
Agency. Radiation Protection Guidance to
Federal Agencies for Occupational Exposure.
Federal Register. 52,2822; January 27,1987.
EP-87a U.S. Environmental Protection
Agency. An Analysis of Evacuation Options
for Nuclear Accidents. EPA 520/1-87-023,
U.S. Environmental Protection Agency,
Washington (1987).
FD-82 Food and Drug Administration.
Potassium Iodide as a Thyroid-Blocking
Agent; in a Radiation Emergency: Final
Recommendations On Use. Federal Register,
47, 28158 - 28159; June 29, 1982.
FE-85 Federal Emergency
Management Agency. Federal Policy on
Distribution of Potassium Iodide Around
Nuclear Power Sites for use as a Thyroidal
Blocking Agent. Federal Register.50, 30256;
July 24, 1985.
FR-64 Federal Radiation Council.
Radiation Protection Guidance for Federal
Agencies. Federal Register. 29,12056-12057;
August 22, 1964.
FR-65 Federal Radiation Council.
Radiation Protection Guidance for Federal
Agencies. Federal Register. 30, 6953-6955;
May 22, 1965.
GL-57 Glasstone, S. The Effects of
Nuclear Weapons. U.S. Atomic Energy
Commission, Washington (1957).
GR-86 Grot, R.A, and A.K. Persily.
Measured Air Infiltration Rates in Eight
Large Office Buildings. Special Technical
Publication 904, American Society for Testing
and Materials, Philadelphia (1986).
IC-77 International Commission on
Radiological Protection. Radiological
Protection, ICRP Publication 26, Pergamon
Press, Oxford (1977).
NA-80 National Academy of Sciences.
The Effects on Populations of Exposure to
Low Levels of Ionizing Radiation: 1980.
Reports of the Committee on the Biological
Effects of Ionizing Radiations. National
Academy Press, Washington (1980).
C-25
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Page Intentionally Blank
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APPENDIX D
Background for Protective Action Recommendations:
Accidental Radioactive Contamination of
Food and Animal Feeds*
*This background document concerning food and animal feeds was published by
the Food and Drug Administration in 1982.
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Page Intentionally Blank
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APPENDIX E
Protective Action Guides for the Intermediate Phase
(Relocation)
Background Information
-------
Page Intentionally Blank
-------
Contents
Page
E.I Introduction . . E-l
E.I.I Response Duration E-l
E.1.2 Source Term E-2
E.1.3 Exposure Pathways E-3
E.1.4 Response Scenario E-4
E.2 Considerations for Establishing PAGs for the Intermediate Phase . . . E-6
E.2.1 Principles E-8
E.2.1.1 Cost/Risk Considerations E-8
E.2.1.2 Protection of Special Groups E-ll
E.2.2 Federal Radiation Protection Guides E-12
E.3 Dose from Reactor Incidents ' E-12
E.4 Alternatives to Relocation E-13
E.5 Risk Comparisons , E-14
E.6 Relocation PAG Recommendations E-15
E.7 Criteria for Reentry into the Restricted Zone E-19
References E-20
Figures
E-l Response Areas E-5
E-2 Potential Time Frame of Response to a Nuclear Incident E-7
E-3 Cost of Avoiding Statistical Fatalities and Exposure Rates
Corresponding to Various Total First Year Doses E-10
E-4 Average Lifetime Risk of Death from Whole Body Radiation Dose
Compared to the Average Risk of Accidental Death from Lifetime
(47 years) Occupation in Various Industries E-16
111
-------
Tables
Page
E-l Brief Descriptions Characterizing Various Nuclear Power Plant
Accident Types (SN-82) E-2
B-2 Release Quantities for Postulated Nuclear Reactor Accidents E-3
E-3 Annual Doses Corresponding to 5 Rem in 50 Years E-13
E-4 Measure of Lifetime Risk of Mortality from a Variety of Causes ... E-17
E-5 Summary of Considerations for Selecting PAGs for Relocation .... E-18
E-6 Estimated Maximum Doses to Nonrelocated Persons from Areas
Where the Projected Dose is 2 REM E-20
IV
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Appendix E
Protective Action Guides for the Intermediate Phase
(Relocation)
Background Information
E.I Introduction
This Appendix provides
background information for the choice
of Protective Action Guides (PAGs) for
relocation and other protective actions
to reduce exposure to deposited
radioactive materials during the
intermediate phase of the response to a
nuclear incident. The resulting PAGs
and associated implementing guidance
are provided in Chapters 4 and 7,
respectively.
This analysis is based on the
assumption that an airborne plume of
radioactive material has already passed
over an area and left a deposit of
radioactive material behind, or that
such material exists from some other
source, and that the public has already
been either sheltered or evacuated, as
necessary, on the basis of PAGs for the
early phase of a nuclear incident, as
discussed in Chapters 2 and 5. PAGs
for subsequent relocation of the public
and other protective actions, as well as
dose limits for persons reentering the
area from which the public is relocated,
are addressed in this Appendix.
We first set forth the assumptions
used to derive information pertinent to
choosing the dose level at which
relocation of the public is appropriate.
This is followed by an examination of
information relevant to this decision,
and selection of the PAG for relocation.
The Appendix concludes with a brief
discussion of the basis for dose limits
for persons temporarily reentering
areas from which the public has been
relocated.
B.I.I Response Duration
In order to decide whether to
initiate relocation of the public from
specific areas it is necessary to predict
the dose that would be avoided. One
factor in this prediction is the duration
of the exposure to be avoided.
Relocation can begin as soon as
patterns of exposure from deposited
radioactivity permit restricted areas to
be identified. For the purpose of this
analysis, relocation of persons who
have not already been evacuated from
the restricted zone is assumed to take
place on the fourth day after the
incident. Return of evacuated persons
to their residences outside the
restricted zone and transition to
relocation status of persons already
evacuated is assumed to occur over a
period of a week or more.
The period of exposure avoided by
relocation ends when the relocated
person either returns to his property or
is permanently resettled in a new
E-l
-------
location. At the time of relocation
decisions, it will usually not be possible
to predict when either of these actions
will occur. Therefore, for convenience
of dose projection, it is assumed that
the period of exposure avoided is one
year and that any extension beyond
this period will be determined on the
basis of recovery criteria. This
assumption corresponds to emergency
response planning guidance by ICRP
(IC-84) and IAEA (IA-85).
E.1.2 Source Term
The "source term" for this analysis
is comprised of the quantities and
types of particulate radioactive
material found in the environment
following a nuclear incident. Nuclear
incidents can be postulated with a wide
range of release characteristics. The
characteristics of the source terms
assumed for the development of these
PAGs are those postulated for releases
from various types of fuel-melt
accidents at nuclear power plants
(SN-82). Table E-l provides brief
descriptions of these accident types.
Radionuclide releases have been
estimated for the three most severe
accident types (SST-1, SST-2, SST-3)
based on postulated core inventories
and release fractions (Table E-2). The
other types (SST-4 and SST-5) would
generally not produce offsite doses from
exposure to deposited material
sufficient to warrant consideration of
relocation.
Table E-l Brief Descriptions Characterizing Various Nuclear Power Plant
Accident Types (SN-82)
Type
Description
SST-1 Severe core damage. Essentially involves loss of all installed safety
features. Severe direct breach of containment.
SST-2 Severe core damage. Containment fails to isolate. Fission product release
mitigating systems (e.g., sprays, suppression pool, fan coolers) operate to
reduce release.
SST-3 Severe core damage. Containment fails by base-mat melt-through. All
other release mitigation systems function as designed.
SST-4 Modest core damage. Containment systems operate in a degraded mode.
SST-5 Limited core damage. No failures of engineered safety features beyond
those postulated by the various design basis accidents. Containment is
assumed to function for even the most severe accidents in this group.
E-2
-------
Table B-2 Release Quantities for Postulated Nuclear Reactor Accidents
Principal
radionuclides
contributing
to dose from.
deposited
materials
Zr-95
Nb-95
Ru-103
Ru-106
Te-132
1-131
CS-134
CS-137
Ba-140
La-140
Estimated quantity released8
(Curies)
Half-life
(days)
6.52E+1
3.50E+1
3.95E+1
3.66E+2
3.25
8.05
7.50E+2
1.10E+4
1.28E+1
1.67
SST-1
1.4E+6
1.3E+6
6.0E+6
1.5E+6
8.3E+7
3.9E+7
8.7E+6
4.4E+6
1.2E+7
1.5E+6
SST-2
4.5E+4
4.2E+4
2.4E+5
5.8E+4
3.9E+6
2.6E+5
1.2E+5
5.9E+4
1.7E+5
5.1E+4
SST-3
1.5E+2
1.4E+2
2.4E+2
5.8E+1
2.6E+3
1.7E+4
1.3E+2
6.5E+1
1.7E+2
1.7E+2
aBased on the product of reactor inventories of radionuclides and estimated fractions released for
three accident categories (SN-82).
For other types of source terms,
additional analysis may be necessary to
assure adequate protection. For
example, if the release includes a large
proportion of long-lived radionuclides,
doses will continue to be delivered over
a long period of time, and, if no
remedial actions are taken, the dose
delivered in the first year may
represent only a small portion of the
total dose delivered over a lifetime. On
the other hand, if the release consists
primarily of short-lived radionuclides,
almost the entire dose may be
delivered within the first year.
From the data in Table E-2? it is
apparent that, for the groups of
accidents listed, both long and short
lived radionuclides would be released.
Consequently, doses due to deposited
materials from such accidents would be
relatively high during the first year
followed by long term exposures at
lower rates.
E.I.3 Exposure Pathways
The principal exposure pathway to
members of the public occupying land
contaminated by deposits of radioactive
materials from reactor incidents is
expected to be exposure of the whole
body to external gamma radiation.
Although it is normally expected to be
of only minor importance, the
inhalation pathway would contribute
E-3
-------
additional doses to internal organs.
The health risks from other pathways,
such as beta dose to the skin and direct
ingestion of dirt, are also expected to
be minor in comparison to the risks
due to external gamma radiation
(AR-89). Skin and inhalation dose
would, however, be important exposure
pathways for source terms with
significant fractions of pure beta
emitters, and inhalation dose would be
important for source terms with
significant fractions of alpha emitters.
Since relocation, in most cases,
would not be an appropriate action to
prevent radiation exposure from
ingestion of food and water, these
exposure pathways have not been
included in this analysis. They are
addressed in Chapters 3 and 6. In
some instances, however, where
withdrawal of food and/or water from
use would, in Itself, create a;health
risk, relocation may be an appropriate
alternative protective action. In this
case, the committed effective dose
equivalent from ingestion should be
added to the projected dose from
deposited radionuclides via other
pathways, for decisions on relocation.
E.1.4 Response Scenario
This section defines the response
zones, population groups, and the
activities assumed for implementation
of protective actions during the
intermediate phase.
After passage of the radioactive
plume, the results of environmental
monitoring will become available for
use in making decisions to protect the
public. Sheltering, evacuation, and
other actions taken to protect the
public from the plume will have
already been implemented. The tasks
immediately ahead will be to (1) define
the extent and characteristics of
deposited radioactive material and
identify a restricted zone in accordance
with the PAG for relocation, (2)
relocate persons from and control
access to the restricted zone, (3) allow
persons to return to areas outside the
restricted zone, (4) control the spread
of and exposure to surface
contamination, and (5) apply simple
decontamination and other low-cost,
low-risk techniques to reduce the dose
to persons who are not relocated.
Because of the various source term
characteristics and the different
protective actions involved (evacuation,
sheltering, relocation, decontamination,
and other actions to reduce doses to "as
low as reasonably achievable" levels),
the response areas for different
protective actions may be complex and
may vary in size with respect to each
other. Figure E-l shows a generic
example of some of the principal areas
involved. The area covered by the
plume is assumed to be represented by
area 1. In reality, variations in
meteorological conditions would almost
certainly produce a more complicated
shape.
Based on plant conditions or other
considerations prior to or after the
release, members of the public are
assumed to have already been
evacuated from area 2 and sheltered in
area 3. Persons who were evacuated or
1-4
-------
M
en
ARBITRARY SCALE
PLUME TRAVEL
DIRECTION
LEGEND
| | 1. PLUME DEPOSITION AREA.
L...J
2. AREA FROM WHICH POPULATION IS EVACUATED.
3. AREA IN WHICH POPULATION IS SHELTERED.
4. AREA FROM WHICH POPULATION IS RELOCATED (RESTRICTED ZONE).
FIGURE E-1. RESPONSE AREAS.
-------
sheltered as a precautionary action for
protection from, the plume but whose
homes are outside the plume deposition
area (area 1) are assumed to return to
their homes or discontinue sheltering
when environmental monitoring
verifies the outer boundary of area 1.
Area 4 is the restricted zone and is
defined as the area where projected
doses are equal to or greater than the
relocation PAG. The portion of area 1
outside of area 4 is designated as a
study zone and is assumed to be
occupied by the public. However,
contamination levels may exist here
that would be of concern for continued
monitoring and decontamination to
maintain radiation doses "as low as
reasonably achievable" (ALAEA).
The relative positions of the
boundaries shown in Figure E-l are
dependent on areas evacuated and
sheltered. For example, area 4 could
fall entirely inside area 2 (the area
evacuated) so that relocation of persons
from additional areas would not be
required. In this case, the relocation
PAG would be used only to determine
areas to which evacuees could return.
Figure E-2 provides, for
perspective, a schematic representation
of the response activities expected to be
in progress in association with
implementation of the PAGs during the
intermediate phase of the response to a
nuclear incident.
E.2 Considerations for Establishing
PAGs for the Intermediate Phase
The major considerations in
selecting values for these PAGs for
relocation and other actions during the
intermediate phase are the four
principles that form the basis for
selecting all PAGs. Those are
discussed in Section E.2.1. Other
considerations (Federal radiation
protection guidance and risks
commonly confronting the public) are
discussed in Sections E.2.2 and E.5.
In addition, a planning group
consisting of State, Federal, and
industry officials provided
recommendations in 1982 which EPA
considered in the development of the
format, nature, and applicability of
PAGs for relocation. Abbreviated
versions of these recommendations are
as follows:
a. The PAGs should apply to
commercial, light-water power reactors.
b. The PAGs should be based
primarily on health effects.
c. Consideration should be given to
establishing a range of PAG values.
d. The PAGs should be established as
high as justifiable because at the time
of the response, it would be possible to
lower them, if justified, but it probably
would not be possible to increase them,
e. Only two zones (restricted and
unrestricted) should be established to
simplify implementation of the PAGs.
E-6
-------
tn
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III
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T i i nun i i i linn i i i i
PERIOD OF
RELEASE.
DISPERSION,
DEPOSITION,
SHELTERING,
EVACUATION,
AND ACCESS
CONTROL
(NO TIME SCALE)
Q
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a.
O
o
z
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E
55
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&
ui
o
CONDUCT AERIAL AND GROUND SURVEYS. DRAW ISODOSE RATE LINES.
IDENTIFY HIGH DOSE RATE AREAS. CHARACTERIZE CONTAMINATION.
0.1
RELOCATE POPULATION FROM HIGH DOSE RATE AREAS.
ALLOW IMMEDIATE RETURN OF EVACUEES TO NONCONTAMINATED AREAS.
ESTABLISH RESTRICTED ZONE BOUNDARY AND CONTROLS.
RELOCATE REMAINING POPULATION FROM WITHIN RESTRICTED ZONE.
GRADUALLY RETURN EVACUEES UP TO RESTRICTED ZONE BOUNDARY.
CONDUCT D-CON AND SHIELDING EVALUATIONS AND ESTABLISH PROCEDURES
FOR REDUCING EXPOSURE OF PERSONS WHO ARE NOT RELOCATED.
PERFORM DETAILED ENVIRONMENTAL MONITORING.
PROJECT DOSE BASED ON DATA.
DECONTAMINATE ESSENTIAL FACILITIES AND THEIR ACCESS ROUTES.
RETRIEVE VALUABLE AND ESSENTIAL RECORDS AND POSSESSIONS.
REESTABLISH OPERATION OF VITAL SERVICES.
BEGIN RECOVERY ACTIVITIES.
CONTINUE RECOVERY.
MONITOR AND APPLY
ALARA IN OCCUPIED
CONTAMINATED AREAS.
i i i MIIII i M i inn i i i 11
I Mill
1.0 10 100
TIME AFTER DEPOSITION (DAYS)
1,000
FIGURE E-2 POTENTIAL TIME FRAME OF RESPONSE TO A NUCLEAR INCIDENT.
-------
f. The PAGs should not include past
exposures.
g. Separate PAGs should be used for
ingestion pathways.
h. PAGs should apply only to
exposure during the first year after an
incident.
Although these PAGs apply to any
nuclear incident, primary consideration
was given to the case of commercial
U.S. reactors. In general, we have
found it possible to accommodate most
of the above recommendations.
E.2.1 Principles
In selecting values for these PAGs,
EPA has been guided by the principles
that were set forth in Chapter 1. They
are repeated here for convenience:
1. Acute effects on health (those that
would be observable within a short
period of time and which have a dose
threshold below which they are not
likely to occur) should be avoided.
2. The risk of delayed effects on
health (primarily cancer and genetic
effects, for which linear nonthreshold
relationships to dose are assumed)
should not exceed upper bounds that
are judged to be adequately protective
of public health, under emergency
conditions, and are reasonably
achievable.
3. PAGs should not be higher than
justified on the basis of optimization of
cost and the collective risk of effects on
health. That is, any reduction of risk
to public health achievable at
acceptable cost should be carried out.
4. Regardless of the above principles,
the risk to health from a protective
action should not itself exceed the risk
to health from the dose that would be
avoided.
Appendix B analyzed the risks of
health effects as a function of dose
(Principles 1 and 2). Considerations
for selection of PAGs for the
intermediate phase of a nuclear
incident differ from those for selection
of PAGs for the early phase primarily
with regard to implementation factors
(i.e., Principles 3 and 4). Specifically,
they differ with regard to cost of
avoiding dose, the practicability of
leaving infirm persons and prisoners in
the restricted zone, and avoiding dose
to fetuses. Although sheltering is not
generally a suitable alternative to
relocation, other alternatives (e.g.,
decontamination and shielding) are
suitable. These considerations are
reviewed in the sections that follow.
E.2.1.1 Cost/Risk Considerations
The Environmental Protection
Agency has issued guidelines for
internal use in performing regulatory
impact analyses (EP-83). These
include consideration of the appropriate
range of costs for avoiding a statistical
death. The values are inferred from
the additional compensation associated
with employment carrying a higher
than normal risk of mortality and are
expressed as a range of $0.4 to $7
E-8
-------
million per statistical death avoided.
The following discussion compares
these values to the cost of avoiding
radiation-induced fatal cancers through
relocation.
The basis for estimating the
societal costs of relocation are analyzed
in a report by Bunger (BU-89).
Estimated incremental societal costs
per day per person relocated are shown
below. (Moving and loss of inventory
costs are averaged over one year.)
Moving $1.70
Loss of use of residence 2.96
Maintain and secure vacated
property 0.74
Extra living costs 1.28
Lost business and inventories 14.10
Extra travel costs 4.48
Idle government facilities 1.29
Total
The quantity of interest is the dose
at which the value of the risk avoided
is equal to the cost of relocation. Since
the above costs are expressed in
dollars/person-day, it is convenient to
calculate the dose that must be avoided
per-person day. The equation for this
is:
where:
HE =
C
VR
HE = dose
C = cost of relocation
V = value of avoiding a
statistical death
R = statistical risk of death from
radiation dose
Using the values cited above, and
a value for R of 3xlO"4 deaths/rem (See
Appendix B), one obtains a range of
doses of about 0.01 to 0.2 reni/day.
Thus, over a period of one year the
total dose that should be avoided to
justify the cost of relocation would be
about 5 to 80 rem.
These doses are based on exposure
accumulated over a period of one year.
However, exposure rates decrease with
time due to radioactive decay and
weathering. Thus, for any given
cumulative dose in the first year, the
daily exposure rate continually
decreases, so that a relocated person
will avoid dose more rapidly in the first
part of the year than later. Figure E-3
shows the effect of changing exposure
rate on the relationship between the
cost of avoiding a statistical death and
the time after an SST-2 accident (See
Table E-l) for several assumed
cumulative annual doses. The curves
represent the cost per day divided by
the risk of fatality avoided by
relocation per day, at time t, for the
annual dose under consideration,
where t is the number of days after the
accident. The right ordinate shows the
gamma exposure rate (mR/h) as a
function of time for the postulated
radionuclide mix at one meter height.
The convex downward curvature
results from the rapid decay of
short-lived radionuclides during the
first few weeks following the accident.
Since the cost per day for relocation is
assumed to be constant and the dose
avoided per day decreases, the cost
effectiveness of relocation decreases
with time. For this reason it is cost
E-9
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10 15 20
TIME AFTER ACCIDENT (days)
25
30
FIGURE E-3.
COST OF AVOIDING STATISTICAL FATALITIES AND
EXPOSURE RATES CORRESPONDING TO VARIOUS
TOTAL FIRST YEAR DOSES (ASSUMES AN SST-2
ACCIDENT AND A $27 PER PERSON-DAY COST OF
RELOCATION).
E-10
0.2
0,3
0.4
0.5
0,6
0.7
0.8
0.9
1.0
8
9
1 0
2 0
30
40
-------
effective to quickly recover areas where
the population has been relocated at
projected doses only marginally greater
than the PAG.
Only trends and general
relationships can be inferred from
Figure E-3 because it applies to a
specific mix of radionuclides. However,
for this radionuclide mix, cost analysis
supports relocation at doses as low as
one rem for the first week and two rem
for up to 25 days after an accident.
B.2.1.2 Protection of Special Groups
Contrary to the situation for
evacuation during the early phase of an
incident, it is generally not practical to
leave a few persons behind when most
members of the general population
have been relocated from a specified
area for extended periods of time.
Further, no data are available on
differing risks of relocation for different
population groups. In the absence of
such data, we have assumed that these
risks will be similar to those from
evacuation. Those risks were taken as
equivalent to the health risk from
doses of SO mrem for members of the
general population and of 150 mrem for
persons at high risk from evacuation
(see Appendix C). Therefore, to satisfy
Principle 4 for population groups at
high risk, the PAG for relocation
should not be lower than 150 millirem.
Given the arbitrary nature of this
derivation, it is fortunate that this
value is much lower than the PAG
selected, and is therefore not an
important factor in its choice.
Fetuses are a special group at
greater risk of health effects from
radiation dose than is the general
population, but not at significantly
greater risk from relocation itself. The
risk of mental retardation from fetal
exposure (see Appendix B) is
significant. It is affected by the stage
of pregnancy relative to the assumed
one-year exposure, because the 8th to
15th week critical period during which
the risk is greatest, must be considered
in relation to the rapidly changing dose
rate. Taking these factors into
account, it can be postulated that the
risk of mental retardation due to
exposure of the fetus during the
intermediate phase will range from one
to five times the cancer risk of an
average member of the public,
depending upon when conception
occurs relative to the time of the
incident. The elevated risk of
radiation-induced cancer from exposure
of fetuses is less significant, as
discussed in Appendix B.
It will usually be practicable to
reduce these; risks by-establishing a
high priority for efforts other than
relocation to reduce the dose in cases
where pregnant women reside near the
boundary of the restricted zone.
However, women who are less than
seven months pregnant may wish to
relocate for the balance of their
pregnancy if the projected dose during
pregnancy cannot be reduced below 0.5
rem.
E-ll
-------
B.2.2 Federal Radiation Protection
Guides
The choice of a PAG at which
relocation should be implemented does
not mean that persons outside the
boundary of the restricted zone should
not be the subject of other protective
actions to reduce dose. Such actions
are justified on the basis of existing
Federal radiation protection guidance
(FR-65) for protecting the public,
including implementation of the
principle of maintaining doses "as low
as reasonably achievable" (ALARA).
The intended actions to protect the
public from radiation doses on the
basis of Radiation Protection Guides
(RPGs) are those related to source
control. Although it is reasonable for
members of the public to receive higher
exposure rates prior to the source term
being brought under control, the
establishment of acceptable values for
relocation PAGs must include
consideration of the total dose over the
average remaining lifetime of exposed
individuals (usually taken as 50 years).
The nationally and internationally
recommended upper bound for dose in
a single year from man-made sources,
excluding medical radiation, is 500
mrem per year to the whole body of
individuals in the general population
(IC-77, FR-65). These recommend-
ations were not developed for nuclear
incidents. They are also not
appropriate for chronic exposure. The
ICRP recommends an upper bound of
100 mrem per year, from all sources
combined, for chronic exposure (IC-77).
The corresponding 50-year dose at 100
mrem/yr is 5 rem. We have chosen to
limit: a) the projected first year dose to
individuals from an incident to the
Relocation PAG, b) the projected second
year dose to 500 mrem, and c) the dose
projected over a fifty-year period to 5
rem. Due to the extended duration of
exposures and the short half-life of
important radioiodines, no special
limits for thyroid dose are needed.
E.3. Dose from Reactor Incidents
Doses from an environmental
source will be reduced through the
natural processes of weathering and
radioactive decay, and from the
shielding associated with part time
occupancy in homes and other struct-
ures. Results of dose calculations
based on the radiological character-
istics of releases from three categories
of postulated, fuel-melt, reactor
accidents (SST-1, SST-2, and SST-3)
(SN-82) and a weathering model from
WASH-1400 (NR-75) are shown in
Table E-3. This table shows the
relationship between annual doses for
the case where the sum, over fifty
years, of the effective dose equivalent
from gamma radiation and the
committed effective dose equivalent
from inhalation of resuspended
materials is 5 rem. Radioactive decay
and weathering reduces the second
year dose from reactor incidents to 20
to 40 percent of the first year dose,
depending on the radionuclide mix in
the release.
Based on studies reported in
WASH-1400 (NR-75), the most
conservative dose reduction factor for
E-12
-------
Table E-3 Annual Doses Corresponding to 5 Rem in 50 Years8
Dose According to Accident Category11 (rem)
Year
SST-1 SST-2 SST-3
1
2
3
4
5
6
7
8
9
10
11
12
15
20
25
30
40
50
1.25
0.52
0.33
0.24
0.18
0.14
0.12
0.10
0.085
0.080
0.070
0.060
0.055
0.045
0.040
0.030
0.025
0.020
1.60
0.44
0.28
0.20
0.16
0.12
0.11
0.085
0.075
0.070
0.060
0.055
0.045
0.040
0.035
0.030
0.020
0.015
1.91
0.38
0.24
0.17
0.13
0.11
0.090
0.070
0.065
0.060
0.050
0.050
0.040
0.030
0.025
0.025
0.020
0.010
"Whole body dose equivalent from gamma radiation plus committed effective dose equivalent from
inhalation assuming a resuspension factor of 10"e m"1. Weathering according to the WASH-1400
model (NR-75) and radioactive decay are assumed.
bEadionuclide abundance ratios are based on reactor inventories from WASH-1400 (NR-75).
Release quantities for accident categories SST-1, SST-2 and SST-3 are shown in Table E-2. Initial
concentrations are assumed to have decayed for 4 days after reactor shutdown.
structures (frame structures) is about relocated to 60 percent (or less) of the
0.4 (dose inside divided by dose values shown in Table E-3 before the
outside) and the average fraction of application of decontamination.
time spent in a home is about 0.7.
Combining these factors yields a net
dose reduction factor of about 0.6. In E.4. Alternatives to Relocation
most cases, therefore, structural
shielding would be expected to reduce Persons who are not relocated, in
the dose to persons who are not addition to dose reduction provided by
E-13
-------
partial occupancy in homes and other
structures, can reduce their dose by the
application of various techniques. Dose
reduction efforts can range from the
simple processes of scrubbing and/or
flushing surfaces, soaking or plowing of
soil, removal and disposal of small
spots of soil found to be highly
contaminated (e.g., from settlement of
water), and spending more time than
usual in lower exposure rate areas
(e.g., indoors), to the difficult and time
consuming processes of removal,
disposal, and replacement of
contaminated surfaces. It is
anticipated that simple processes
would be most appropriate to reduce
exposure rates for persons living in
contaminated areas outside the
restricted zone. Many of these can be
carried out by the residents with
support from officials for monitoring,
guidance on appropriate actions, and
disposal. The more difficult processes
will usually be appropriate for recovery
of areas from which the population is
relocated.
Decontamination experiments
involving radioactive fallout from
nuclear weapons tests have shown
reduction factors for simple
decontamination methods in the
vicinity of 0.1 (i.e., exposure rate
reduced to 10 percent of original
values). However, recent experiments
at the Riso National Laboratory in
Denmark (WA-82, WA-84), using
firehoses to flush asphalt and concrete
surfaces contaminated with radioactive
material of the type that might be
deposited from reactor accidents, show
decontamination factors for
radionuclides chemically similar to
cesium that are in the range of 0.5 to
0.95, depending on the delay time after
deposition before flushing is applied.
The factor for ruthenium on asphalt
was about 0.7 and was independent of
the delay of flushing. The results of
these experiments indicate that
decontamination of the important
reactor fission products from asphalt or
concrete surfaces may be much more
difficult than decontamination of
nuclear weapons fallout. Other simple
dose reduction methods listed above
would be effective to varying degrees.
The average dose reduction factor for
gamma radiation from combinations of
simple decontamination methods is
estimated to be at least 0.7.
Combining this with the 40 percent
reduction estimated above for
structural shielding indicates that the
doses listed in Table E-3 may be more
than twice as high as those which
would actually be received by persons
who are not relocated.
E.5 Risk Comparisons
Many hazardous conditions and
their associated risks are routinely
faced by the public. A lingering
radiation dose will add to those risks,
as opposed to substituting one risk for
another, and, therefore, radiation
protection criteria cannot be justified
on the basis of the existence of other
risks. It is, however, useful to review
those risks to provide perspective. This
section compares the risks associated
with radiation doses to those associated
with several other risks to which the
public is commonly exposed.
E-14
-------
Figure E-4 compares recent
statistics for the average lifetime risk
of accidental death in various
occupations to the estimated lifetime
risk of fatal cancer for members of the
general population exposed to radiation
doses ranging up to 25 rem.
Non-radiation risk values are derived
from information in reference (EP-81)
and radiation risk values are from
Appendix B, These comparisons show,
for example, that the lifetime cancer
risk associated with a dose of 5 rem is
comparable to the lifetime risk of
accidental death in some of the safest
occupations, and is well below the
average lifetime risk of accidental
death for all industry.
Risks of health effects associated
with radiation dose can also be
compared to other risks facing
individuals in the general population.
The risks listed in Table E-4 are
expressed as the number of premature
deaths and the average reduction of
life-span due to these deaths within a
group of 100,000 persons. For
purposes of comparison, a dose of 5
rem to each member of a population
group of 100,000 persons
representative of the average U.S.
population carries an estimated
lifetime risk of about 150 fatal cancers
(see Appendix B). The number of
deaths resulting from the various
causes listed in Table E-4 is based on
data from mortality records.
In summary, the risk of premature
death normally confronting the public
from specific types of accidents ranges
from about 2 to 1000 per 100,000
population. The estimated radiation
doses required to produce a similar risk
of death from radiation-induced cancer
range from about 0.07 to 33 rem.
E.6 Relocation PAG Recommendations
Previous sections have reviewed
data, standards, and other information
relevant to establishing PAGs for
relocation. The results are
summarized in Table E-5, in relation to
the principles set forth in Section E.2,1.
Based on the avoidance of acute
effects alone (Principle 1) 50 rem and
10 rem are upper bounds on the dose
at which relocation of the general
population and fetuses, respectively, is
justified. However, on the basis of
control of chronic risks (Principle 2) a
lower upper bound is appropriate. Five
rem is taken as an upper bound on
acceptable risk for controllable lifetime
exposure to radiation, including
avoidable exposure to accidentally
deposited radioactive materials. This
corresponds to an average of 100 mrem
per year for fifty years, a value
commonly accepted as an upper bound
for chronic annual exposure of
members of the public from all sources
of exposure combined, other than
natural background and medical
radiation (IC-77). In the case of
projected doses from nuclear reactor
accidents, a five rem lifetime dose
corresponds to about 1.25 to 2 rem
from exposure during the first year and
0.4 to 0.5 rem from exposure during
the second year.
Analyses based on Principle 3
(cost/risk) indicate that considering cost
E-15
-------
tu
cc
2
ui
c
CL
u,
o
10'3
cc
ui
I
u.
CC
tu
CONSTRUCTION & MINING
AGRICULTURE
•TRANSPORTATION & PUBLIC UTILITIES
'AVERAGE FOR ALL UTILITIES
"GOVERNMENT
.SERVICE
• MANUFACTURING
' RETAIL &
WHOLESALE
TRADE
8 10 12 14 16 18
rem (effective dose equivalent)
20 22 24 26
FIGURE E-4. AVERAGE LIFETIME RISK OF DEATH FROM WHOLE BODY RADIATION DOSE
COMPARED TO THE AVERAGE RISK OF ACCIDENTAL DEATH FROM LIFETIME
(47 YEARS) OCCUPATION IN VARIOUS INDUSTRIES.
E-16
-------
Table B-4 Measure of Lifetime Risk of Mortality from a Variety of Causes8
(Cohort Size = 100,000)
Nature of
accident
Falls
Fires
Drowning
Poisoning
Premature
deaths
1,000
300
190
69
Aggregate years
of life lost
to cohort
12,000
7,600
8,700
2,500
Reduction of
life expectancy
at birth (years)
0.12
0.076
0.087
0.025
Average years
of life lost to
premature deaths
11
26
45
37
by drugs and
medicaments
Cataclysm13
Bites and
stings0
Electric
current
in homes'1
17
8
8
490
220
290
0.005
0.002
0.003
30
27
37
aAll mortality effects shown are calculated as changes from the U.S. Life Tables for 1970 to life
'tables with the cause of death under investigation removed. These effects also can be interpreted
as changes in the opposite direction, from life tables with tike cause of death removed to the 1970
Life Table. Therefore, the premature deaths and years of life lost are those that would be
experienced in changing from an environment where the indicated cause of death is not present to
one where it is present. All values are rounded to no more than two significant figures.
bCataclysm is defined to include cloudburst, cyclone, earthquake, flood, hurricane, tidal waves,
tornado, torrential rain, and volcanic eruption.
"Accidents by bite and sting of venomous animals and insects include bites by centipedes,
venomous sea animals, snakes, and spiders; stings of bees, insects, scorpions, and wasps; and other
venomous bites and stings. Other accidents caused by animals include bites by any animal and
nonvenomous insect; fallen on by horse or other animal; gored; kicked or stepped on by animal; ant
bites; and run over by horse or other animal. It excludes transport accidents involving ridden
animals; and tripping, falling over an animal. Babies is also excluded.
dAccidents caused by electric current from home wiring and appliances include burn by electric
current, electric shock or electrocution from exposed wires, faulty appliances, high voltage cable,
live rail, and open socket. It excludes burn by heat from electrical appliances and lighting.
E-17
-------
Table E-5 Summary of Considerations for Selecting PAGs for Relocation
Dose Consideration Principle
(rem)
50 Assumed threshold for acute health effects in adults. 1
10 Assumed threshold for acute health effects in the fetus, 1
6 Maximum projected dose in first year to meet 0.5 rem in the second
year*. 2
5 Maximum acceptable annual dose for normal occupational exposure
of adults. 2
5 Minimum dose that must be avoided by one year relocation based
on cost. 8
3 Minimum projected first-year dose corresponding to 5 rem
in 60 years". 2
3 Minimum projected first-year dose corresponding to 0,5 rem in the
second year8, 2
2 Maximum dose in first year corresponding to 5 rem in 50 years from a
reactor incident, based on radioactive decay and weathering only. 2
1.25 Minimum dose in first year corresponding to 5 rem in 50 years from a
reactor incident based on radioactive decay and weathering only. 2
0.5 Maximum acceptable single-year dose to the general population from
aU sources from non-recurring, non-incident exposure. 2
0.5 Maximum acceptable dose to the fetus from occupational exposure
of the mother. 2
0,1 Maximum acceptable annual dose to the general population from all
sources due to routine (chronic), non-incident, exposure. 2
0.03 Dose that carries a risk assumed to be equal to or less than that
from relocation. 4
"Assumes the source term is from a reaetor incident and that simple dose reduction methods are
applied during the first month after the incident to reduce the dose to persons not relocated from
contaminated areas.
E-18
-------
alone would not drive the PAG to
values less than 5 rem. Analyses in
support of Principle 4 (risk of the
protective action itself) provide a lower
bound for relocation PAGs of 0.15 rem.
Based on the above, 2 rem
projected committed effective dose
equivalent from exposure in the first
year is selected as the PAG for
relocation. Implementation of
relocation at this value will provide
reasonable assurance that, for a reactor
accident, a person relocated from the
outer margin of the relocation zone
will, by such action, avoid an exposure
rate which, if continued over a period
of one year, would result in a dose of
about 1.2 rem. This assumes that 0.8
rem would be avoided without
relocation through normal partial
occupancy of homes and other
structures. This PAG will provide
reasonable assurance that persons
outside the relocation zone, following a
reactor accident, will not exceed 1.2
rem in the first year, 0.5 rem in the
second year, and 5 rem in 50 years.
The implementation of simple dose
reduction techniques, as discussed in
section E-4, will further reduce dose to
persons who are not relocated from
contaminated areas. Table E-6
summarizes the estimated maximum
dose that would be received by these
persons for various reactor accident
categories with and without the
application of simple dose reduction
techniques. In the case of non-reactor
accidents these doses will, in general,
differ, and it may be necessary to apply
more restrictive PAGs to the first year
in order to assure conformance to the
second year and lifetime objectives
noted above.
Since effective dose does not
include dose to the skin (and for other
reasons discussed in Appendix B)
protective action to limit dose to skin is
recommended at a skin dose 50 times
the numerical value of the PAG for
effective dose. This includes
consideration of the risk of both
curable and fatal cancers.
E.7 Criteria for Reentry into the
Restricted Zone
Persons may need to reenter the
restricted zone for a variety of reasons,
including radiation monitoring,
^recovery work, animal care, property
maintenance, and factory or utility
operation. Some persons outside the
restricted zone, by nature of their
employment or habits, may also receive
higher than average radiation doses.
Tasks that could cause such exposures
include: 1) changing of filters on air
handling equipment (including
vehicles), 2) handling and disposal of
contaminated vegetation (e.g., grass
and leaves) and, 3) operation of control
points for the restricted zone.
Individuals who reenter the
restricted zone or who perform tasks
involving exposure rates that would
cause their radiation dose to exceed
that permitted by the PAGs should do
so in accordance with existing Federal
radiation protection guidance for
occupationally exposed workers
(EP-87). The basis for that guidance
has been provided elsewhere (EP-87).
E-19
-------
Table E-6 Estimated Maximum Doses to Nonrelocated Persons From Areas
Where the Projected Dose is 2 REM*
Dose (rem)
Accident
Category
SST-1
SST-2
SST-3
No additional dose
Year 1
1.2
1.2
1.2
Year 2
0.5
0.34
0.20
reduction
50 years
5.0
3.9
3.3
Early simple dose reduction15
Yearl
0.9
0.9
0.9
Year 2
0.35
0.24
0.14
50 years
3.5
2.7
2.3
'Based on relocation at a projected dose of 2 rem in the first year and 40 percent dose reduction to
nonrelocated persons from normal, partial occupancy in structures. No dose reduction is assumed
from decontamination, shielding, or special limitations on time spent in high exposure rate areas.
bThe projected dose is assumed to be reduced 30 percent by the application of simple dose
reduction techniques during the first month. If these techniques are completed later in the first
year, the first year dose will be greater.
References
AK-89 Aaberg, Rosanne. Evaluation of Skin
and Ingestion Exposure Pathways. EPA
520/1-89-016, U.S. Environmental Protection
Agency, Washington (1989).
BU-89 Hunger, Byron M. Economic Criteria
for Relocation. EPA 520/1-89-015, U.S.
Environmental Protection Agency,
Washington (1989)
EP-81 U.S. Environmental Protection
Agency. Background Report. Proposed Federal
Radiation Protection Guidance for
Occupational Exposure. EPA 520/4-81-003,
U.S. Environmental Protection Agency,
Washington (1981).
EP-83 U.S. Environmental Protection
Agency. Guidelines for Performing Regulatory
Impact Analysis. EPA-23-01-84-003, U.S.
Environmental Protection Agency,
Washington (1983),
EP-87 U.S. Environmental Protection
Agency. Radiation Protection Guidance to
Federal Agencies for Occupational Exposure.
Federal Register. 52.2822; January 27,1987.
FR-65 Federal Radiation Council. Radiation
Protection Guidance for Federal Agencies.
Federal Register. 30,6953-6955; May 22,1965.
IA-85 International Atomic Energy Agency,
Principles for Establishing Intervention
Levels for Protection of the Public in the
Event of a Nuclear Accident or Radiological
Emergency. Safety Series No.72, International
Atomic Energy Agency, Vienna (1985).
IC-77 International Commission on
Radiological Protection. Radiological
E-20
-------
Protection. ICRP Publication 26, Pergamon
Press, Oxford (1977).
IC-84 International Commission on
Eadiological Protection. Protection of the
Public in the Event of Major Radiation
Accidents: Principles for Planning, ICBP
Publication 40, Pergamon Press, New York
(1984).
NR-75 U.S. Nuclear Regulatory Commission.
Calculations of Reactor Accident
Consequences. WASH-1400, U.S. Nuclear
Regulatory Commission, Washington (1975).
SN-82 Sandia National Laboratories.
Technical Guidance for Siting Criteria
Development. NUREG/CR-2239, U.S. Nuclear
Regulatory Commission, Washington (1982).
WA-82 Wanning, L. Weathering and
Decontamination of Radioactivity Deposited
on Asphalt Surfaces. Riso-M-2273, Riso
National Laboratory, DK 4000 RosMlde,
Denmark (1982). ,
WA-84 Warming, L. Weathering and
Decontamination of Radioactivity Deposited
on on Concrete Surfaces. RISO-M-2473, Riso
National Laboratory, DK-4000 Roskilde,
Denmark. December (1984).
E-21
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APPENDIX F
Radiation Protection Criteria
for the Late Phase
Background Information
(Reserved)
# U.S. GOVERNMENT PRINTING OFFICE: 1992 617-O03/B70Q3
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