UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D,C, 204SO
10, 1988
The Honorable Lee 11. Thomas EFA-SAB-RAC-89-003
Administrator
U. S. Environmental Protection Agency o".eg OF
401 M Street S.W. ™e *OM,N)STR*TOR
Washington, D.C. 20460
Dear Mr. -Thomas:
The Radiation Advisory Committee of the Science Advisory Board has
reviewed the Office of Kadiation Program's plans for revising the technical
basis for the Badionuclides MESHAP. The Science Advisory Board's Dose
and Risk Subcommittee sent you separate reports on Low-LET radiation risks
and on risks associated with radon. This letter transmits the report of
the Sources and Transport Subcommittee,
The Director of the Office of Badiation Programs presented its
approach to the revisions in the May 23, 1988 memorandum, "Badiation Bisk
Assessment Methodology*' and in the June 21, 1988 memorandum, "Review of
Clean Air Act Risk Assessments by Radiation Advisory Cksnnittee." Staff
from the Office of Radiation Programs supplemented these memoranda with
presentations at the open meeting of July 13-15, 1988 . Members of the
public provided extensive written and oral public connent on technical
issues.
In considering whether the Office of Badiation Programs approach was
state-of-the-art and scientifically defensible, the Subcommittee addressed
many issues including; the accuracy and completeness of the technical
data, the validity of the modeling approach, the relevance of the data and
nodeling to the objectives, the presentation of results, and uncertainty.
Of the numerous findings by the Subcommittee, we wish to highlight
three which we believe to warrant the most serious attention by the Agency:
1. Portions of the AIRDOS-EPA methodology are no longer state-of-
the-art, and must be updated to incorporate important recent
advances in modeling radiohuclide transport through environmental
pathways.
2, To date, EPA's treatment of modeling uncertainties has been
qualitative rather than quantitative although state-of-the-art
methods for estimating uncertainty are available,
3. Best estimates (defined on page 9 of the report) with appropriate
uncertainty statements should be used in all risk assessments.
The "best" estimate should be statistically defined, according
to the target population or individual and the shape of the
uncertainty distribution.
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To correct these deficiencies, the Subcommittee urges the
to make use of qualified groups and individuals to help implement immediate
and long-term improvements in model structures, uncertainty and sensitivity
analyses, and model validation. Results from evaluations of similar
radiological assessments are available which the Agency could use now
to guide its immediate activities. Innger-term efforts should involve a
substantive upgrading of radionuclide transport codes and ensure that the
methodology gains and maintains a state-of-the-art status.
Detailed recaimendations which deal with these and other topics are
found in the report.
These concerns aside, the Subcenndttee ccmnends the Agency for its
intentions to present radiation consequences as a function of risk
level, as in the benzene example cited in the presentation; for the initial
steps taken to validate the atmospheric dispersion code within AIRDOS-EPA;
and for the use of simplified models for initial screening in the case of
compliance procedures,
The Subconinittee hopes the Office of Radiation Programs will incorporate
this advice into the Background Information Document and reminds the
Agency that the Radiation Advisory Committee has asked to review Volunes
I and II of the new Background Information Document when they are available.
In considering the results of this review it is important to recall
that very similiar findings and recotroendatlons were offered to the Agency
by the Science Advisory Board in January 1984. The apparent lack of
responsiveness on this matter by the Office of Radiation Programs during
this four year period is of grave concern to the Science Advisory Board.
It is the opinion o£ the Board that action is required now to assure that
future reviews will yield evidence of a more defensible scientific basis
for regulatory decisions on radionuclide emissions.
The Subconinittee appreciates the opportunity to conduct this scientific
review, v& request that the Agency formally respond to the scientific
advice transmitted in the attached report.
Sincerely
.„
Norton Nelson, Chairman
Executive Coroittee
Board
\
William J. schull,j
Radiation Advisoi
Chairman
Ccranittee
ion
Enclosure
Chairman
and Transport Subccoinittee
Advisory Committee
ccx j. Moore
EX Clay
R. Guimond
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"NA11QNAL QUSSIGN STANDARDS FOR HAZA1DOUS AlE POLUUmMTS (NESteP)
SUNMEDS FOR MDIQNUCLIDES"
REVIEW OF ASSESSMQW tffilHODOLOGIES
Sources and Transport Subcommittee
of the
Badlation Advisory Gocmittee
U.S. Environmental Protection Agency
Science Advisory Board
November 1988
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u. s. ENviRONMEwm PROTECTION
NOTICE
this report has been written as a part of the activities of the
Science Advisory Board, a public advisory group providing extramural
scientific information and advice to the Administrator and other officials
of the Environmental Protection Agency. Hie Board is structured to
provide a balanced expert assessment of scientific matters related to
problems facing the Agency. This report has not been reviewed for approval
by the Agency and, hence, the contents of this report do not necessarily
represent the views and policies of the Environmental Protection Agency,
nor of other agencies to the Executive Branch of the Federal government,
nor does mention of trade names or commercial products constitute
a reconmendation for use*
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ABSTRACT
The Environmental Protection Agency's Office of Radiation Programs described
Its plans to update the technical basis supporting the National Bnission
Standard for Hazardous Air Pollutants (NESHAP) for radionuelides. Plans
relating to sources of radtonuclides in the environment, transport
modeling, exposure, sensitivity analysis, and uncertainty analysis were
described in a series of briefings at public meetings and documents
including Radionuclides, BackgroundInformation Document for Final Rules
(1984) and two memoranda ftorn tfe tiirectot of the Office of iadiation
programs "Radiation Risk Assessment Methodology" May 23, 1988 and "Review
of Clean Air Act Msk Assessments by Radiation Advisory Committee,"
June 21, 1988.
The Sources and Transport Subeonntittee of the Science Advisory Board's
Radiation Advisory Conmittee reviewed these plans. Major findings and
reconroendations were made regarding the state-of-the-art of the transport
model (AIRDOS-EPA)» uncertainty and sensitivity analysis, model validation,
and the use of best estimates in risk assessment. The Subcommittee found
that portions of the AIRDQS-EPA methodology are no longer state-of-the-art,
nor are they completely defensible from a scientific viewpoint because
important advances in modeling radionuclide transport have not been
incorporated. Because treatment of modeling uncertainties in radiation
risk assessment by the Office of Radiation Programs has not been quantitative
or rigorous, the assessments cannot be scientifically evaluated. The
Subcommittee reconnended that best estimates with appropriate uncertainty
statements should be used in all risk assessments. The "best" estimate
should be statistically defined, according to the target population or
individual and the shape of the uncertainty distribution.
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u.s. Wfmmmn&L PROTECTION
SCIENCE AOTSQIff BOARD
RADIATION AWISOKf CtMHTTEE
SOURCES AND TRANSPORT SUBCOMMITTEE
ROSTER
Chairman
Dr, John Till
Radiological Assessments Corporation
Route 2, Box 122
Nesses, South Carolina 29107
Manbers/Constiltants
Dr. James E. Martin
University of Michigan
School of Public Health
Ann Arbor, Michigan 48109
Dr* H. Robert Meyer
Chem-Nuclear Systems
Uranium Mill Tailings Remedial
Action Project
Post Office Box 9136 c/o M£-F
Albuquerque, NM 87119
Dr. Steven L. Simon
Department of Environmental Sciences
CB-7400
Rosenau Hall
University of North Carolina
Chapel Hill, North Carolina 27599
Mr, William L. Terapletoti
Battelle Pacific Northwest
Post Office Box 999
Riehland, Washington 99352
Mr. Paul Voilleque
Science Applications International Corporation
101 South lark Avenue - Suite 5
Idaho Falls, Idaho 82402
Dr. F. Ward Whicker
Department of Radiology
and Radiation Biology
Colorado State University
Fort Collins, Colorado 80523
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Executive Secretary
Mrs. Kathleen White Conway
Science Advisory Board (A-101F)
U.S. Environmental Protection Agency
401 H Street S.W.
Washington, DC 20460 '
Staff Secretary
Mrs. Dorothy Clark
Science AiJvisory Board (A-101F)
U.S. Environmental Protection Agency
401 M Street S.W.
Washington, DC 20460
Director
Dr. Donald Barnes
Science Advisory Board (A-101)
U,S. Environmental Protection" Agency
401 M Street S.W.
Washington, DC 20460
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TMLE OF
1.0 INTRODUCTION 1
2.0 OVERALL APPBOACH TO 1HE USE OF DMA AND 3
MODELS IN THE RISK ASSESSMENT
2.1 Use Dose/Risk Assessment Models for 3
Deriving the Radionuclide NESHAP
2.2 Objectives of Assessment Calculations 3
2*3 Input/Output Parameters 4
2,4 Perspective on and Understanding of 4
Calculated Health Risks
2.3 Limitations of Dose Assessment Codes 4
on Mainframe Computers
2,6 Recannendationa on the Use of 5
Models for Radionuclide NESHAP
3.0 SCIENTIFIC BASIS OF RISK ASSESS^! MEIHDDOLOSY 7
3,1 Model Structure 7
3,2 Model Validation 8
3.3 Model Uncertainty 9
(with definition of "best estimate")
m
3.4 Parameter Sensitivity 9
3.5 Ifodel Documentation and Accessibility 10
3*6 Recoamendations on Models Used in the 10
Eadionuclidee Risk Asessment
4,0 USE OF SITE-SP1CIFIC EM3A 11
4.1 Data from Other Federal Programs 11
Should be Incorporated in the BID
4,2 Site-Specific Parameters and Measurements 12
Should be Used Whenever Possible
4.3 Recomendations for the Aquisition and 12
Use of Site-Specific Data
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5.0 UNCEKQUM 13
5,1 The Role of Uncertainty in Risk Analysis 13
5.2 Improvements in the Estimates of Uncertainty 14
5,2,1 Sensitivity Analysis 14
5.2.2 Parameter Variability 14
5.2.3 Propagation of Uncertainty 15
5.3 Recconendation Regarding the Estimation 15
of Uncertainty
6.0 MDDEI5 FCR CCMPLIANCE APPLICATIONS 16
6.1 Application of Simple Models 16
6.2 Recomendation on Alternative Compliance 16
Screening Model Development
7.0 KEEERBKXS " 17
APPENDIX A May 23, 1988 Memorandum from R. J. Guimond
to Donald Barnes: "Radiation Risk Assessment
Methodology", May 23, 1988*
APPENDIX B June 21, 1988 Memorandum from R. J. Guimond
to Donald G. Barnes; "Review of Clean Mr Act
Risk Assessments by Radiation Advisory Coraaittee,"
June 21, 1988.
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1.0 INTRODUCTION
The Science Advisory Board's Radiation Advisory Committee initiated
this review because revision of the "National Bnission Standard for
Hazardous Mr Pollutants; Standards for Radionuclides" (NESHAP) is an
important activity which could benefit from the use of new data and
scientific techniques developed in the last five to ten years, this report
will generally refer to that standard as the "Kadionuclides NESHAP".
the Radiation Advisory Coumittee formed the Sources and Transport
Subeofflflittee to conduct the review. The roster for this Subcommittee
appears at the front of this report. The Subcommittee based its review
on two memoranda (see appendices) from the Director of the Office of
Radiation Programs (GBP) with their attachnaits (1,2), oral presentations
by OBP staff at the July 13-15, 1988 meeting, and public comments.
The objective of this review was to examine the scientific basis for
the evaluation of source terms and radiological assessment models that
will be used in the revisions to the Radionuclides NESHAP Background Information
Documents scheduled for completion late this winter* The Subcommittee
review of the risk assessment methods was scheduled at this time to
assist the Agency in meeting its court-mandated deadlines for issuing a
proposed rulemaking of February 28, 1989.
The following members of the public provided ccuments on July 13, 1988;
Dr. Donald Scroggin of Beveridge and Diamond PC
on behalf of the Idaho Mining Association
Dr. Leonard Hamilton of Brookhaven National Laboratory
Mr. Joe Baretincic of DC Corporation
on behalf of The Fertilizer Institute
Dr. Edwin Still of Kerr-Md3ee
on behalf of the American Mining Congress
Mr. Louis Cook of Chevron Resources Corporation
on behalf of the American Mining Congress
Mr. Tony Thompson of Perkins Cote
on behalf of the American Mining Congress
Dr. Douglas Chambers of SUES Consultants
on behalf of the Americang Mining Congress
and The Fertilizer Institute
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The Subcommittee appreciates these public comments, which were well prepared
and technically enlightening, and believes the information provided should
be considered by the Agency in its ongoing revision to the N1SH6P Background
Information Docunents.
Staff from the Office of Radiation Programs briefed the Subcomnittee
on planned changes to the methodology and data bases that will ultimately
be incorporated into the Background Information Document for the radionuclide
NESHAP. However, since the Office of Radiation Programs is under severe
time constraints, the Subcommittee was not able to review the results of
calculations or revisions to methodologies that will be used. Such
results may not become available until late winter. Therefore, key issues
and recommendations of the Subcommittee are based on its review of previously
documented methods, the appended memoranda and oral presentations by the
Office of Radiation Programs staff.
Since no formal issues were raised by the Agency in preparation for
this review, the Subcommittee, after studying the supporting docunents
and listening to briefings, identified five major topics for discussion.
These topics along with specific recommendations follow*
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2.0 OVERALL APPROACH TO 1HE USE OF W& AND MODELS IN TH£ RISK
2.1 Use Dose/Risk Assessment Models for ^ Deriving the Badicnucllde
NfeSHAP - '
The Subcommittee focused on the extent to which models should be
used in lieu of efforts to obtain measured data; whether the model should
be usable~~far both, deriving a standard and determining compliance; and
the manner in which input/output data are presented, especially the
output data regarding risk distribution and uncertainty.
The Subcommittee concurs with statements of the the Envirooiental
Engineering Committee in its June 1, 1988 draft resolution on modeling (3),
The use of mathematical models for environmental decision-
making has increased significantly in recent years. The reasons
for this are many, Including scientific advances in the under-
standing of certain environmental processes, the wide availability
of computational resources, the increased number of scientists
and engineers trained in mathematical formulation and solution
techniques, and a general recognition of the power and potential
benefits of quantitative assessment methods, Ihe increased
reliance on mathematical models is evident within the U.S. Environtnental
Protection Agency (EPA) , where integrated environmental release,
transport, exposure, and effects models are being developed and used
for rulanaking decisions and regulatory Impact assessments.
Despite its appreciation of modeling, the Subcommittee believes that
measured data -best represent source strengths and environmental concentrations
and also near -source atmospheric and environmental concentrations from
sources subject to complex diffusion (such as near a building complex or
large gypsum or uranium tailings pile) . the use of measured source data
for elemental phosphorous plants is a good example of a case in which EPA has
successfully benefited from this approach, fclhere such data are not
available or cannot be obtained on the schedule required, it is appropriate
to use assessment models.
2,2
Although the 1984 Background Information Doament (4) describes in
Volume 1 Chapter 6 methods to model the movement of radionuclides tteaugh
environmental pathways, it fails to identify clearly the specific objectives
of the calculations. Examples of assessment objectives are: the calculation
of the maximum effective connitted dose equivalent Do the average individual
in an exposed population, the effective dose equivalent per individual
in the most exposed population group and the probability that the average
dose in a critical group does not exceed a predetermined value. Although
the methodology for various objectives may be similar, input data will
differ substantially depending on whether average or highly conservative
estimates are desired.
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The Subcommittee believes that ultimately it Is necessary to estimate
the expected number of health effects in the population as a consequence
of routine emissions (including predictable seasonal and episodic releases)
and to be able to relate this to an expected exposure level. The uncertainty
of the estimated health risks inherently incorporates the uncertainty in the
exposure level. Uierefore, full disclosure of the source and transport
ttncertainty way help quantify the total risk uncertainty and provide
additional input that can be used in setting, emission standards.
2.3 Input/Output Parameters
The Subconinittee is concerned about both how input/output parameters for
dose/risk models are chosen and about the actual parameters selected. This
concern stems from the knowledge that data and it's interpretations which are
clearly and thoroughly presented are more easily understood, more accurately
interpreted, and more readily related to other ccraaon data or studies.
2.4 Perspective on and Understanding of Calculated ifealch Msks
It is essential to provide scientific data and analyses to the
scientific comnunity, to the risk management decision-maker, and to the
public in ways which show that often the calculated health effects may be
derived for a population at very low individual risk. One effective tool
for this purpose is presenting the population distribution of the calculated
risk by individual risk level as is being considered in the draft revised
benzene standard doctraents (5). A decision to ignore very low individual
risk levels is clearly risk management rather than risk assessment;
however, the data should be available to decision makers in a way that
provides the perspective necessary for informed judgments. Similarly,
comparisons of these estimated risk levels with other commonly encountered
and accepted risks is necessary for perspective*
2.5 Limitations of Dose Assessment Codes on Mainframe Copguters
The Subcommittee understands that the Agency is proceeding to develop
a replacement code for AIRDOS-EPA. These new models will be embodied in
a Conputerized Radiological Risk Investigation System (CBRIS) on mainframe
machines. Models implemented on mainframe computers are generally
inaccessible to all but a few specialists, are difficult to modify, and
are expensive. Ihe restriction on accessibility limits interaction with
peer and interested user groups with the result that state-of-the-art
methodologies rarely get widely implemented in a timely manner. Current
generation microcomputers are approximately equivalent in power to late
1970's mainframe machines on which current EPA dose assessment codes were
written. It has been demonstrated that many transport ana dose models
can now be implemented on current generation personal computers.
The advantage of dose assessment models implemented on microcomputer
systems is that they can routinely be made available for peer-rewiew.
Such interactions would likely result to significant state-of-the-art
improvements being made to the Agency's methodology at no cost to the .
Agency.
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2.6 Reconnendationson the Use of'fiodels' for Radionuclides 'MESHAg
Clearly the use of measured data as the basis for the Radionuclldes
NESHAP is preferable to calculations! models whaiever it can be reasonably
obtained because there is no need to estimate exposures if real and
representative data are used. For example, measured ambient air concentration
are more defensible than an estimate of air concentration based on an
approximate source term and an atmospheric dispersion model, Mien used
with care, models can be and are a necessary tool for deriving and complying
with the Badionuclides NESHAP; however, attention should be given to
uncertainties and the presentation of model inputs and outputs in understandable
and useful formats. The Subcommittee makes the following recommendations
concerning the use of models for the radtonuclidea NiSHAP:
1. The EPA should use site-specific measured data on source terms
and environmental concentrations especially for sources that represent
complex assessment situations where current models fail. EPA should
also use site-specific measured data, or at least generic study
results, where available, for other input parameters to the models*
2. Where sufficient data are not- available, the EPA must apply
updated state-of-the-art ealculatianal models to its derivation of
the radionuclides NESHAP, To do so, EPA must intensify its efforts
to employ current and state-of-the-art nodels for each major model
conponent used to determine the risk to public health from various
radionuclide emissions sources. EPA muse also incorporate both
recent advances in modeling methods and the results of validation
studies In environmental transport and plume dispersion models*
3. The EPA must clearly state the objectives of the risk assessment
calculations. The Subcommittee recommends clarifying both the
objectives of the assessments and the steps necessary in the ecological
and dosimetric modeling to meet those objectives. Statements of
objectives are necessary to provide information regarding the intended
conservatism or realism of the assessment calculations. The
clarification of objectives will also serve as a guide in making
decisions to use conservative or realistic model assumptions and
in the choice parameter values. Specifying the objectives will be
invaluable in justifying the choice of parameter values, thus making
the results more defensible*
4. The Subcommittee strongly suggests that dose estimates be
realistic, relevant to defined populations, and accompanied by
a quantitative statement of uncertainty which can be propagated
into the dose-risk framework. Scenarios can be used as part of
this approach. For example, if continuous exposure at a certain
location is part of the scenario, the occupancy factor is fixed (at
1UO%) and only the variations in the other parameters contribute to
the uncertainty estimate.
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5. Hie EPA must clearly display input:/output parameters used in
the calculational models for the iadionuelides NESHAP risk assessment.
Particular attention should be given to the population distribution of
calculated health effect estimates among the population at risk.
These estimates must be displayed as a table showing the distribution
of risks over the population, broken down by such categories as:
a. the individual risk level,
b. the size of the population subgroup at that risk
level, and
c, the estimated incidence of particular effects that
occur at the given individual risk level in the particular
population subgroup.
The Subcommittee strongly supports the presentation of calculated
risk data for the ladionuclides NESHAP standards in a format similar to
that in the memorandum on benzene (5).
When preparing supporting documents for the Eadionuclides NESHAP, EPA
should display all assumptions, Input parameters and research and
studies upon tthich they were based* The presentation of uncertainties
(See Section 5.0) will also contribute to greater credibility and
understanding of the risk assessment process,
6. All dose assessment computer codes for radionuclides should be
developed for use on microcomputers unless code size and complexity
requirsients justifies the use of mainframe machines. Such codes
must be made readily available for review by outside peer, expert,
and user groups.
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3.0 SCIENTIFIC BASIS OF RISK ASSESSMENT METHODQljQSY
Portions of the AIIDQS-EPA methodology are no longer state-of-the-art,
and must be updated to incorporate important recent advances in modeling
radionuclide transport through environmental pathways. The current
transport methodology was state-of-the-art and scientifically defensible
some 5-10 years ago. However, EPA's general methodology, and the radionuclide
transport sections of AIRDQ8-EPA in particular, have not changed substantiveiy
since that time. Many advances have been made in the field of modeling
radionuclide transport within the last five years but 1PA has not incorporated
such advances into its own methodology* Examples of such advances that
are not currently reflected in AIEDOS-EPA are discussed below under the
categories of model structure, model validation, model uncertainty, parameter
sensitivity, and model documentation and accessability,
3.1 Model Structure
The food chain portion of AIRDOS-EPA is a steady-state model adapted
from earlier codes such as HEKiES(6)and formulations in the U.S, Nuclear
Regulatory Commission Guide 1,109(7). The main differences between
AIRDOS-EPA and these earlier methodologies involve the choice of certain
parameter values. The depositlon-ingestion sections of AIBDQS-EPA are
baaed on straightforward formulae that are well-documented and generally
accepted. The choices of parameter values are generally based on relevant
scientific literature.
The Subcommittee favors the use of dynamic models because there are
distinct disadvantages of steady-state models such as AIRDOS-EPA. For
example, predictions of steady-state models only apply accurately to chronic,
constant release scenarios. In practice, enissions from many types of
facilities are not constant, but rather episodic or seasonal. Furthermore,
steady-state models are not well-suited to handle the very marked seasonal
changes in climatological conditions, agricultural practices, and food
distribution patterns. Finally, steady-state models are not fully testable
because many data sets are in the form of time-series measurements, which
cannot be directly compared to steady-state model predictions. In short,
steady-state foodchain models are limited in application, not realistic,
and not readily subject to direct validation. Several dynamic foodchain
models have been developed outside EPA, including RAGTIME (8), 1CCSYS (9)
RADFOOD(10)and PATHWffif(H). These codes incorporate the dynamic processes
necessary for more realistic simulation of radionuclide transport ttawigh
the environment. Dynamic models of course, do handle chronic, steady-state
release easily, and they are not difficult to structure or program.
Numerous parameters which are known to vary considerably in time
and space are treated as constants to AIRDOS-EPA* These include, for
example, the pasture intake of dairy cows, the foliar interception
fraction, and the source fraction of various foods to people in a particular
locale. Recent, more updated models, have successfully dealt with these
variations to produce more realistic estimates (11).
Several basic pathways which are frequently important in the natural
environment are not included in AIRDOS-EPA. For exanple, resuspension of
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. 8 -
recent deposits cm the soil by wind or ocher disturbance is a. very important
process for arid and semi-arid environments, especially sfaan longer-lived
radionuclides are involved (11). Sensitivity analyses for many simultaneously
varying parameters reveal that resuspension can be, in some cases, a
dominant process affecting dose to man (12), Another example of omitted
pathways in AIRJDOS-EPA is soil ingestion, both by cattle and people,
especially children. Itese phenomena, and numerical estimates, are
well-doaiaented in the literature (11,13)* The relative importance of soil
ingestion is usually small, but under some circumstances, this pathway
can be considerably more important than others, "these pathways, by their
omission, may in sorae cases offset the gaierally conservative choices of
parameter values in AIWBS-EPA.
As another example of shortcooings in model structure, to the atmospheric
diffusion portion of AIRDQS-EPA, the code does not deal adequately with
cotiplex terrain and building wake effects, furthermore, the use of the
harmonic mean of morning and afternoon lid heights throughout the day was
questioned by the Subcommittee.
3.2 tfedel Validation
Efforts by 13PA to validate or test the accuracy of AIRDQS-iPA appear
to, have been minimal, especially for'that portion of the model subequent
to dispersion which treats deposition, environmental transport and ingestion.
The Gaussian plume model portion, however, has been compared to real data
sets with encouraging results* for which EPA should be conmended. Without
a good deal of effort to validate as many steps in the risk assessment
calculations as is possible, the results will always be subject to criticism
by the public, as well as the scientific community* For exanqsle, there
has already been considerable criticism by representatives of industry
who claim that due to over-conservatism in the assessment models, the
regulatory standards are unreasonably restrictive. Others are likely to
look for the other extreme, arguing that standard are too permissive.
Without convisctag model validation data, !PA will be unsure of their
degree of conservatism or accuracy and therefore have continual difficulty
in defending some of its regulatory positions.
Hie field of radlonuclide transport model validation is relatively
new, but rapid advances are currently being made in the U.S. and in
mmerous other countries* We are rapidly progressing froa peer-review
and model comparison exercises to real-world coraparsions between model
predictions and independent field data sets. Because of its scrutiny
by peers and the courts, the PAlHWff model received fairly exhaustive
validation testing some five years ago with data sets made possible by
extensive foodchain sampling programs in the western U*S, during the
latter part of the weapons fallout era (14). More recently, the BICHDVS
(Biospheric Model Validation Study) effort was initiated by the Swedish
Government and has matured into a truly international effort, involving
some 15-20 nations. The BIQMQVS program gained exceptional momentum
from the Chernobyl accident, which resulted in the accumulation of
extensive data sets from at least a dozen sites world-wide. Active U.S.
participants have not included people from EPA. A similar model validation
effort has been initiated as a Coordinated Research Program by the International
Atomic liiergy Agency, but again, without EPA participation.
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m 9 -.
Clearly, model validation is crucial to the achievement of public
and scientific credibility of risk assessments. A reasonable, workable
methodology exists, as do numerous data sets* There is ample opportunity
for EPA to bolster its effort in the area of model validation.
3.3 Model Uncertainty
The general field of risk assessment is rapidly moving away from the
practice, of giving single, perhaps wrst-caie estimates, to that of,'
jarwHing best estimates along vidh" YVtatement of the uncertainty of
tnat best* estimate.Uiis new, evolving practice reflects the attempt
by scientific modelers to exercise complete honesty and full disclosure
in arriving at dose or risk estimates. All model structures and parameter
values have inherent and unavoidable uncertainties which owe to real-world
complexity and variability, as well as to a lack of knowledge, data, or
both. Therefore all model predictions contain corresponding uncertainties,
Without rigorously derived uncertainty estimates, the credibility of
dose or risk values cannot be judged. My enlightened reviewer will
likely assign a very low credibility to an estimate not accompanied by a
statement of uncertainty*
In the case of AIRDQS-EPA, it is clear that little or no formal
propagation of uncertainties through the methodology has been carried
out. While data with which to construct uncertainty distributions on
many parameters is lacking, it is still reasonable to construct such
distributions, reflecting the actual degree of ignorance on the part
of the modeler. Methods for propagating uncertainties through radicwuclide
transport models are available (15,16), as are published estimates of
uncertainty for many critical transport parameters (12,17,18,19)*
3.4 Parameter Sensitivity
An important aspect of model evaluation is that of xmderstanding the
relative degree- to which individual processes or parameters affect the
model prediction, and the degree to which uncertainty in a parameter
affects model output uncertainty* A sensitivity analysis can be carried
out simultaneously with an uncertainty analysis (12), or it may be done
independently. Modeling is seldom perfect, so as long as needs justify
and resources permit, modelers should strive Co continually evaluate and
improve their models* Conducting a series of sensitivity analyses is the
most efficient way to reveal the most influential pathways and parameters»
and thus to guide the expenditure of resources and effort for the sake of
model improvement. Sensitivity analysis techniques are readily available
and have been successfully applied to dose assessment models (11,12,20),
It is not evident to the Subcommittee that EPA has made any substantive
effort in the area of sensitivity analysis related to the Eadionuclides
N1SHAP or, in particular, AIRDQS-EPA.
The Subcommittee defines "best estimate" as the arithmetic mean in the
case of normal distributions and the geometric mean (median) in the
case of log-normal distributions. The best estimate for other distribution
shapes requreg specific statistical definition to avoid confusion.
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- 10 -
3.5 Model Documentation and Accessability
The current EPA codes for radiation dose assessment are not clearly
and concisely documented, nor are Chey readily available for outside use
or peer review, this hinders progressive evolution of the codes because
independent critique and input is made difficult. It is useful to concisely
document models in the open literature so that they can be openly examined*
Such documentation should include a clear statement of the objectives of
the models, including a definition of the target individuals or population
groups to *hich the output applies aa well as a careful exposition of and
justification for the model structure and parameter values. The advances
in the power and speed of personal computers have been shown to make
possible their use for many complex models. The ability to distribute
models enhances the process of positive model evolution.
3.6 Seconipetujlaticos on Models Used in EPA's Radionuclide Risk Assessment
1. The Office of Radiation Programs must become state-of-the-art in
its risk assessment methodologies. Ihe transport portions of AIRDOS-EPA
need extensive revisions. Methods already developed by other groups for
model validation, uncertainty and sensitivity analysis need to be incorporated.
This task nay be accomplished taost efficiently by establishing a close,
continuing working relationship with a group or individuals acknowledged
to be current in these fields. Immediate use of uncertainty estimates and
validation exercises from other transport models is essential if EPAs short-term
goals for NESHAP development are to be achieved. For the longer-term,
EPA should develop its own capabilities with the help of others and
participate more actively to national and international meetings devoted
to these topics*
2. The Office of Radiation Programs should carefully define the
generic individuals and/or populations to which its risk assessments are
targeted and carefully articulate these definitions in the Background
Information Document and other relevant documents.
3. The dose/risk assessments conducted by EPA must provide best
estimates (as defined on page 9) along with statistically appropriate
measures of uncertainty. The probabilitites of individuals receiving
doses or risks at various fractions or multiples of the best estimates
should be clearly revealed in all numerical presentations.
4. As the Office of Radiation Programs develops new software to
accomplish dose/risk assessments, codes compatible with personal computers
should be encouraged. This strategy is not only coat-effective, but it
facilitiates future improvements, communication capabilities, and credibility
within the public and scientific community.
These recoraaendations are consistent with, and in some cases almost
identical to, those developed during the Science Advisory Board's 1984
review (21).
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_ 11 _
4.0 THE USE OF SITE-SPECIFIC DATA
4.1 Data from Other Federal Programs Should be Incorporated in the BID
The EPA is noc always using the most appropriate data available in the
performance ot radionuclide NESHAP development. Since preparation of the
Background Information Document in 1984, a great deal of new data, of
significant potential value to this
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- 12 -
4*3 Recommendations for the Aqulsition and Use of Additional Data
1. The EPA should initiate a thorough survey of all current remedial
action programs sponsored by the government. !he survey should identify
key personnel within each project capable of quickly providing the relevant
data, Tne Oak Ridge National Laboratory's report, Remedial Action Contacts
Directory. M»uld be a good starting point, (24)
2. The EPA should request immediate access to other federal data
relevent to the Badfonuclides NESHAP work. Uiese data include the following.
a. Radioactive particulate concentrations.
b. Nonradioactive dust concentrations, (Supplementary, for
comparison purposes),
c. Radon and other radioactive gas concentrations.
d. Meterological data.
e. Radionuclide concentrations in the specific source material
(e.g., tailings or gypsum stacks)*
f. Particle size information (pile and airborne).
g. Solubility information (standardized lung fluid tests).
h. Quality control information defining conditions -under which
the data were collected and analyzed.
3, The EPA should use existing data sets to correct the results of
AIRDQS-EPA for specific sites. For example, environmental monitoring
data provided by the Mount Taylor representatives and the New Mexico
Environmental Improvement Division study of radon concentrations in the
Grants New Mexico area, would provide a basis for evaluating the results
of AIRDQS-EPA predictions for that specific mine's emissions. EPA should
perform similar corrections for all other facilities for liiich measured
concentration data are available.
4. Data sets acquired from outside sources must be inspected
carefully for systematic quality control errors, to allow evaluation of
the accuracy of results employing that information.
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- 13 -
5.0
5,1 The Role of Oncertainty ^' in ,'Msfc' Analysis
Because quantitative estimates of the uncertainty provide very important
information tQ~the decision maker and others concerned with Che risk
decision, the Subcommittee recommends in strongest terns that EPA make
quantitative estimates of the uncertainty associated with the Agency's
dose and risk estimates. Calculations of uncertainty clarify the reliability
of the central estimate and provide information essential to understanding
the reliability of the estimate,
In 1984, the Science Advisory Board recommended (21) that the Office
of Radiation Programs explicitly present uncertainties as part of the
radionuclides risk assessment. The Office of Managanent and Budget (25) »
the Office of Science and Technology Policy (26) » the National Science
Foundation (27) » and the EPA Administrator (5) , have further emphasized
the need for defining uncertainties in risk assessments.
the October 1984 Background Information Document (4) summarizes
(Vol. I, p. 7-29) some sources of uncertainty and the "reasonable" accuracy
which was stated to be a factor of three to four* Ihe problem with this
qualitative approach is that there is no way to substantiate the stated
range even though a "factor of three to four" may correctly describe the
accuracy of dose calculations to represent typical members of the population.
This assumed range of error in the source term and environmental transport
is close to that estimated for the dose response models (e.g., QKP's
risk estimate of 120-750 lung cancers per million person WW» with a
central estimate of 300, implies an uncertainty factor of 2.5). (28)
Because the uncertainty in the source term and environmental transport
models is believed to be of the same order of magnitude as that for
dose-response models , uncertainty estimates for source terms and transport
play an important role in establishing the total uncertainty of the
calculations of health effects*
The uncertainty statement , however, must have an interpretation that is
understood and preferably is of use in decision making. The uncertainty
estimate is more than simply a statement about lack of knowledge. Given
the proper conceptual framework, e.g. establishing probability distributions
of parameters based upon expert judgement or data, the uncertainty estimate
can be used to express the probability that the true dose does not exceed
a specific value. This framework enables the uncertainty estimate to be
used in a meaningful way for decision making*
To avoid misleading the decision-maker, uncertainty statements should
also be accompanied by a discussion of what the model does and does not
include. To the extent that a model omits certain pathway or processes ,
it is incomplete, however, uncertainty analysis cannot assess the
completeness of a model. Because uncertainty analysis, can only reflect
the pathways a«i/or processess accounted for in the model, it cannot
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. 14 -
defensibly compensate for the emissions of pathways and/or processes.
For example, to AIRDQS-EPA the absence of relevant pathways (as identified
in Section 3.0, page 7) cannot be adequately accounted for by uncertainty
analysis without arbitrarily inflating the total uncertainty in an indefensible
manner,
5*2 Improvements in the Estimates of uncertainty
It is essential that the EPA progress from qualitative, estimates
of uncertainty to soundly based numerical estimates that cover all
portions of the calculations. The need for estimates of the uncertainty
in the risk assessment results was identified in the initial review of
the SAB in 1984 (21). Although some qualitative and numerical estimates
were given for portions of the source, transport, and dose calculations
in the 1984 BID, the overall uncertainty in the estimates of dose was not
evaluated in an integrated and focused manner (4).
The QKP has stated its intention to again provide qualitative estimates
of uncertainty and believes them to -be adequate (2), The Subcommittee
strongly disagrees because the proposed QBP approach is not state-of-the-art
and the argument that it is too difficult to perform a quantitative
evaluation is not valid. Currently the capabiliity to perform Msnte
Carlo calculations yielding probability distributions for the dose estimates
is widely available on personal computers. Techniques for these stochastic
calculations have been described and used by several other groups in
similar evaluations of dose from particular sources of radionuclides
released to the environment. (References 12,15,16,17,20, and 29, for
example)* The available techniques and desktop calculations! capabilities
permit the improvements recommended below to be accomplished in a timely
manner.
5.2,1 Sensitivity Analysis; The Agency must perform sensitivity analyses
to identify ther most critical parameters for the important exposure pathways
for the various source categories. The EPA has already identified some
critical exposure pathways as the result of dose calculations presented
in the 1984 Background Information Docuaent. (See Table 7.6-1, Volume 1
page 7-28 and the assessments for specific source categories in Volime 2.)
For most of the categories» inhalation is the critical pathway. Food
chain transport was found to be important for the "DOE facility" category
and may also be important for the t®C licensee and other federal facility"
and the "uranium fuel cycle" facility categories.
5.2.2 Parameter Variability: The EPA must define the distributions of
the most important parameters identified in the sensitivity analyses.
The problems in establishing reasonable probability distributions are
often less difficult than expected for several reasons. This procedure
can be facilitated by establishing the maximum conceivable range of
values and the estimate of central tendency, Multiplicative models have
been shown not to be extremely sensitive to distribution shape, a finding
that can be confirmed by modifying distribution types and comparing
results produced by the various assumed distributions. The EPA must
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- 15 -
also define the distributions of the measurements or estimates of the
source terns for the various categories.
5.2.3 Propagation t^of _ttacertainty: For each source category, the EPA
should perform Sonte "Carlo calculations to determine the dose distribution
that results from variations of the critical parameters. Note that these
calculations can often be performed separately on a personal computer
without running AIRDOS-EPA repetitively. This is accomplished using a
reduced model which explicitly considers only the critical variables.
The reduced model should yield nearly the same final result as the
coi$>lex model. Hottte Carlo calculations are then performed for those
variables to generate frequency distributions for the estimated dose.
Calculations such as those performed by Dr. Chambers and submitted as
part of his testimony on July 13, 1988 exemplify what can be done (30),
It is also possible that analytical error propagation methods may
work sufficiently well for simple exposure pathways. Tnose pathways,
e.g. inhalation, that are not modeled by a large mmber of parameters or
processes may be especially amenable to this treatment. It appears that
for 8 of the 11 source categories in dP's June 21 aemorandtin (2), inhalation
may be the main exposure pathway. The principal differences between the
pathways would be the variability of the source term and local meteorology.
When assumptions must be made regarding the shape of input parameter
distributions, the uncertainties of parameters will also reflect the lack of
knowledge of environmental processes. Uncertainty statements should also
be made for systematic errors which result in model bias. Model bias was
seen for individual sites in the comparison of AIRDOS-EPA with measured
values (31). For any one site, the predictions were consistently above
or below the taeasured values. Such comprehensive evaluations significantly
contribute to the ability to make quantitative uncertainty statements.
For example, the spread of predictions after adjustment for the observed
bias can be used as an estimate of the uncertainty in downwind air concentrations,
at least for the sites considered in the comparison.
5,3 EBomeatime^d^_he Estimation of tftrartauity
The Subcommittee strongly recommends that the EPA make quantitative
estimates of uncertainty for the risk assessment for each source category.
These uncertainty estimates and their bases need to be presented as part
of the Radionuclides NESHAP.
The EPA does not have time to conduct a comprehensive quantitative
uncertainty analysis of AIBEQS before publication of the revised proposal
in February 19S9. It is, however, both possible and desireable for the
Agency to make some interim quantitative estimate of uncertainty based on
studies of similar models. Therefore, the EPA should acquaint itself with
ongoing and completed studies of uncertainty in environmental transport
models, report the nature of the uncertainties studied and their magnitudes,
and discuss those findings and models in relation to AIRDOS. The sensitivity
analysis, studies of parameter variability, and propagation of uncertainty
identified above will take longer to complete and should therefore be
started promptly so that they may be used in the final regulations. Experienced
people could be realistically expected to complete such work within two years.
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- 16 -
6.0 ropEis. TOR.
6,1 Application of Simple Models
The commercial and non-conmercial use of radtonuclides Is licensed
by U.S. Nuclear Regulatory Commission (NiC). A large proportion of these
licensees involve the use of small quantities of radionuclides which
likely represent a very small risk to the public. The Subcommittee
believes that the series of computer codes presently employed by the
Agency for the Radionuclides NESHAP are complex and virtually unavailable
to most scientists and other users because they are on main frame computers.
These limitations for demonstrating compliance must be recognized. Ihe
Subcommittee believes that an approach originally reconmeuded by the
National Council on Radiation Protection and Measurements (NQRP) , of
applying the most simple models first, followed by a more coop lex model,
if necessary, is appropriate (32). It is, therefore encouraging to
note that the Agency recognizes that other simple, user-friendly and less
costly model programs are available P can meet the same objectives, and
would be more appropriate to demonstrate compliance. However, a formal
process must be established for comparing the results of any alternative
methodologies with that of the IPA's to facilitate their approval and use,
A tiered approach which meets this criteria is being proposed for determining
compliance using Annual Possession and Mr Concentration Tables, application
of Level II and III of the NCRP Screening Model (33) and/or EPA's microcomputer
Code (COMPLY). This methodology appears to be based on sound environmental
transport and radiation protection principles, however, the Subcommittee
has not specifically reviewed these methods in any detail for such compliance
applications.
6,2 Recommendations on Alternative Cknpjj.anee Screening Model DevelOEjaent
The Subcommittee recommends that EPA develop criteria for the evaluation
of alternative compliance models and publish a process for gaining their
approval. The Subcommittee strongly supports the IPA's proposed tiered
approach for NBC License compliance and recommends its application for
the Eadionuclides NESHAP. The Subcommittee also strongly encourages EPA
to subject these compliance procedures to peer-review. High priority
must be given to making the proposed methodologies available to users in
a timely manner.
The Subcommittee also encourages EPA to apply the same philosophy
and approach, i.e. simple models first, followed by more complex methods,
where appropriate to assess compliance for categories of sources other
than radionuclides,
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- 17 -
7.0 REFERENCES
1, R.J. Guimond, Memorandum to Donald Barnes; Subject: "Radiation Msk
Assessment Methodology", May 23, 1988,
2. R. J. Gutmond, Memorandum to Donald G. Barnes; Subject: "Review of
Clean Air Act Risk Assessments by Radiation Advisory Committee,"
June 21, 1988.
3. Science Advisory Board, Environmental Engineering Gonmittee,
SAB-*EEC Resolution' on' the ' Ose' of ' Ifej^emtical'ttedels ' for' Integrated
lOTsi .Assessment in Rule* and ^ision-Ilgd^ at_EgAf Draft by
Mitchell Snail dated June 1988.
4. Envitomental Protection Agency* 1 984 Kadlonuclideg . Background Information
Document for. Ji-^faiLeB t Volumes I and I'f. '"'* M™L- .....
5. Lee M. Thomas, Memorandum on "Proposed Benzene NESHAP Decisions and
Limitation of Issue to Section 112 of the Clean Air Act," April 5, 1988,
6, Fletcher, J. F, and W. L, Dotson* 1979, HUMES; A Digital Computer
Code for Estimating Regional Radiological Effects from the Nuclear
Power Industry. Battelle Northwest Laboratory. HEEL-IKE-? 1-1 §8
7. U.S* Nuclear Regulatory Commission. 1977. 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.
8. G.G. Killough and F.O. tfoffman* 1988, Validation of the M5TIME87
Dynamic Food-Chain Model Against Fallout Datafrom the Chernobyl
Accident. J. Tem^afeia£1Sci.' €3J*SS^''"'?a^^*r' . ' *
,,,: .
9. H.G. Paretzke, P. Jacob, fcijpBller. and S. Prohl. 1988. Concept
and Validation Studies of the Real-Time Seactor-Accidesnt Consequences
Assessment Model "ECCJSfS". Abstract in Radiation Protection Practice.
Volume I. Proceedings of the 7th IIPA. Congress. Author's address;
GSF-Institote for Radiation Protection, P-8042, Ifeuherberg,
Federal Republic of Germany.
10, Koch, J. and J, Tadmor. 1986. RABFOQD-A. Dynamic Model for
Radioactivity Transfer Through the ftnan Foodchain. Realtii
Phys. 50:721-737,
11. Whicker, F, W. , and T. S3. Kirchner. 1987. PATHWHi A Dynamic
Food-Chain Model to Predict Radionuclide Ingestton After Fallout
Deposition. Health Phys. 52 (6): 71 7-737,
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- 18 -
12. Otis, M. D. 1983* Sensitivity and Uncertainty Analysis of Che PATHiS
Radixmuclide Transport Model. Ph.D. Dissertation, Colorado State
University, Fort Collins, CO,
18.
13. La^oy, P. K. 19B7, Estimated soil ingestion rates for use in risk
assessment. Risk Anal. 7:355-359.
14. Kirehner, T. B. and F. W. Whicker. 1984. Validation of PATHWAY:
A Sinulation Model of the Transport of ladionuclldes Ifarough
Agroeeosystens. Icol. Modelling, 22:21-44.
15. R. 0. Gilbert. 1984. Assess ing 'Uncertainty' in Pollutant, transport Models.
1RANS-STAT, Statistics for Environmental Studies, Novaaber 27,
PNL-SA-12521,
16. F. 0. ftoffiaan and 1, H. Gardner. 1983. Evaluation of Uncertainties to
Radiological Assessment Models in Radiological Assessment, J. £» Till
and H, E. Meyer (Eds.), Nuclear Regulatory Commission report,
NURBS/CR-3332.
17. Hoffinan, F, 0. and C. F* Baes, III. 1979. A Statistical Analysis
of Selected Parameters for Predicting Food Chain Transport and Internal
Dose of Radionuclides. Oak iidge National Laboratory, Oak Ridge, TN»
NURffi/CR-1004/OBNL/NUiiEHM-282.
Iman, R. L. and J* C, Helton. 198S. An investigation of uncertainty
and sensitivity analysis techniques for conpiter models. Risk Anal.
8:71-90.
19. Breshears, D. D. 1987. Uncertainty and sensitivity analyses of simulated
concentrations of radionuclides in milk. M.S. Thesis. Colorado State
University, Ft. Collins. 95p.
20. R. L. Man, J. C. Helton, and J* E* Campbell. 1981. An Approach to
Sensitivity Analysis of Computer Models, Part II - Banking of Input
Variables, Response Surface Validation, Distribution Effect and
Technique Synopsis, Journal of Quality Technology, Jl(4): 232-239.
21. Science Advisory Board Subcommittee on Risk Assessment for Radionuclides
Report on the Scientific Basis for IPA's Proposed National Qaission
Standards for Hazardous Air Pollutants for Mdionuclides, August 1984.
22. Mayer, H. R., C. Begley and C, Daily, "Held Instruments Developed for
Use on the UMJffiA. Project," Proceedings of the Waste Management 1987
Annual Meeting, University of Arizona, Tucson, March 1987.
23. Ifeyer, H. R. and C. Daily, "QA Verification Procedures in Uranian Mill
Tailings Processing Site Remedial Action", Proceedings of the American
Society for Quality Control, Second Topical Conference on Nuclear
Waste Management Quality Assurance, Las Vegas, Nevada,
February 9-11, 1987
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- 19 -
24, Knox, !. M. (publisher). tenediai^ Aetiotx' Cbptacts ' Directory
QMNL/TH- 10807. May 1988. Available" from tfie Remedial Action Program
Center at Oak Ridge National Laboratory*
25. Office of Management and Budget, Letter from Wendy Gram (CMS) to
Lee Thomas (EPA), August 12, 1986.
26. Office of Science _ and Technology Policy, Oftjg. Comments.' on gA Guidelines
for Carcinogenic Risk Assessment, July 15, Y986. ' " "
27. National Science Foundation, Letter from David T* Kingabury (NSF) to
James Kamihachi (EPA), July 25, 1986.
28, Science Advisory Board, Sibcamittee on Risk Assessment, Letter to
Lee M. Thomas (EPA), July 11, 1988,
29, G, Schwarz and F. 0. Hoffinan. 1980. "Inprecisions of Dose Predictions for
Badionuclides Released to the Envirortoent: An Application of a
Monte Carlo Simulation Technicque, fegiroiC' jnteri^iqnal , 14: 289-297.
30* Douglas B» Chambers, Presentation ' to Sources ' ^d ^ Transport 'Subcociaittee
of the Badiatioti Advisory' Ooami'ttee"»'' Icicnee Advisory Board", ""
U.S« Environiaental Protection Agency, Jtily 13, 1988.
31. S, K, Beal, et al. » Cqroari_8gn_ of^Ai&I^_-El>A Predict iona of Ground-
Level Airborne JMionuctrdecehtra^^
Manuscript dated October 1987.
32. National Council on Radiation Protection and Measuraients (NCEP) .
1 984. Radigl^lcal Assessment; Predicting die' Transport,
Moaccumiiation,, and^ Uptake by Man of MdiotBicIia^" Ifelias_ed_. tp__the.
'ESwironiient. ...... tJORF Report. N6V 76'. '
33. National Council on Eadiation Protection and Measurements (NCRP),
1986. .Scr^iiittTedttiiqugs for Detepnininj^ Compliance with
Er^rcrapgital Staidards , Releas^ of RadianucTi^es to the Atmosphere,
NCRP CkUBentary kfo.Tt ' '
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APPENDIX A
>
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASH1XGTON, D.C 20460 "
MAY 2 3 1988
; i
SUBJECT; Radiation Risk Assessment Methodology \
1 * i y ^""""^ " ti
FROM; Richatd J, Guimond, Director L. »J-*'* .Jv-'
Office of Radiation Programs (ANR-458), "~
TO: Donald Barnes, Director
Science Advisory Board (A-101)
At our April 12," 1988, meeting on radionuclide HESHAPS,
we agreed to supply past background documents used to support
NESHAPS rulemaking. Attached .for transmission to the Radiation
Advisory Committee of the science Advisory Board (SAB) ace copies
of the background information documents produced in support of
the various Clean Air Act radionuciide rulemafcings. A copy of
the latest document describing our risk assessment methodology,
to be used in support of a low-level radioactive waste management
standard, is also attached,
The risk assessment methodology that will be usei to
develop new background information documents will be virtually
identical to that used in the past with respect to source,
dispersion, and pathway modeling. However, we propose to incor-
porate a dose-risk factor range of 120 to 1200 fatal cancers per
million person-rem to account for the uncertainty in that factor.
The central estimate of risk for whole-body, low-let radiation to
the general public will be determined by using a risk factor of
400 fatal cancers per million person-rem, corresponding to the
linear, relative-risk model in BEIE III* The whole-body risk
will be allocated among the Various target organs, consistent
with an organ specific relative risk model for all cancers other
than leukemia and bone cancer,
Also, we propose to base the radon risk estimates on the
preferred model contained in BSIR IV. We will send you another
memorandum which expands on our proposed treatment of radon and
requests your comments.
. *
other modifications to the methodology will compute the
effective dose equivalent, as defined by XCRP, and the radon
equilibrium ratio as a function of distance from a radon source.
-------
Of lesser importance, we propose to make adjustments in our
thyroid risk estimates in light of current information as
summarized in NCR? Report NO, 80, First, the estimate of 20%
mortality for radiation-induced thyroid cancer would be changed
to 10%. The 20% figure relates to mortality from _all thyroid
cancers; however, there is ample evidence that the types of
thyroid cancer induced by ionizinf radiation have a mortality of
only about 101. Second, 1-131 would be considered to be one-
third as effective as x-rays for induction of thyroid cancer,
rather than one-tenth, as assumed previously. The data regarding
this question are incomplete and somewhat conflicting—one animal
study has shown 1-131 to- be considerably more effective than
previously thought *
11 is extremely important that we obtain your review of our
current risk assessment methods and our proposed changes to these
methods by August 1, 1988, This date is made necessary by our
plans to finish the recalculation of risk assessments by early
September in, order to have decision documents ready for Agency
and Administrator reviews this fall. We will make every attempt
to incorporate youc comments as we proceed* lowever, our
schedule is inflexible due to a court-mandated proposal date of
February 2S, 1389. If we receive your comments after Aufust 1,
198S, we may not be able to utilize them in performing the risk
assessment which will support*'the development of the proposed rule
although it may be possible to take note of your comments in the .
preamble to the proposed rule and consider them for the final rule,
which has a court-mandated promulgation date of August 31, 193f.
If the Radiation Advisory Committee has any questions about the
attached material or our approach to risk assessment, please let me
know*
5 Attachments
cc: Gordon Burley (ANK-458J
j. William Gunter (ANR-4SQ)
TerrenceA, McLaughlin (ANfi-460)
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Uriied S;SKS
Environmental Protection
Agtncv
Office of
Ridiaiion Programs
Washington. D-C. 20460
CA .
October
0. "-;--v^2"
&EPA
Background information
Document For Final Rules
Volume I
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COHfENtS
Figures
Tables
1. INTRODUCTION
Page
viii
1-1
History of Standards Development 1-1
Purpose of the Final Background Information Document 1-2
Scope of the Final Background Information Document
E?A's Computer Codes
2. CURRENT REGULATORY PROGRAMS AMD STRATEGIES
2. 1 Introduction
2.2 The International Commission on Radiological Pro-
tection and the National Council on Radiation
Protection and Measurement*
2.3 Federal Guidance
2.4 The Environmental Protection Agency
2.5 Nuclear Regulatory Commission
2.5.1 Fuel Cycle Licenses
2.5.2 Byproduct Material licenses
2.6 Department of Energy
2.7 Other Federal Agencies
2.7.1 Bureau of Radiological Health
2.7.2 Mine Safety and Health Administration
2.7.3 Occupational Safety and Health
Administration
Department of Transportation
2.7.4
2.. 8 State Agencies
3. HAZABD
3.
3.
3.
3,
3.
I Bv-iteBcJ^hae fcdiation
2 "Evidence that Radiation I* Mtrragenie
3 Evidence that Radiation Is Teratogenic
4 Uncertainties
5 Summary of Evidence That Radiation is a Carcinogen,
Mutagen, and Teratogen «^,
4. EMISSION OF RADIOHUCtlDSS IHTO HE All
4.1 Introduction
4.2 Sources of Radionuclide Releases into the Air
1-2
1-4
2-1
'2-1
2-2
2-8
2-10
2-12
2-12
2-13
2-13
2-14
2-14
2-14
2-14
2-14
2-15
3-1
3-1
3-6 '
3-9
3-10
3-11
4-1
4-1
4-2
iii
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CONTENTS (continued)
Page
4.2.1 Department of Energy (DOE) Facilities 4-2
4,2.2 Nuclear Regulatory Comnissiou (KRC)
Licensed Facilities and non-DOE
Federal Facilities 4-13
4.2.3 Coal-Fired Utility and Industrial
Boilers 4-19
4.2.4 Underground Uranium Mines 4-19
4.2.5 Phosphate lock Processing and Wet-
Process Fertilizer Plants 4-20
4.2.6 Elemental Phosphorus Plants 4-22
4.2.7 Mineral Extraction Industry Facilities 4-23
4.2.8 Uranium Fuel Cycle Facilities* Uranium
Mill failings. High-level Hast*
Management 4-2?
4.2.9 Low-Energy Accelerators 4-31
4.3 Radionticlide Releases 4-31
4.3.1 Department of Energy Facilities 4-32
4.3.2 NIlC-Licensed Facilities and Non-DOE
Federal Facilities 4-32
4.3.3 Coal-Fired Utility aad Industrial
loilers 4-35
4.3.4 Underground Uranium Mines 4-35
4.3.5 Phosphate Rock Processing aad Wet-
Process Fertilizer Plants 4-36
4,3*6 Elemental Phosphorus Plants 4-36
4,3.7 Mineral Extraction Industry 4-37
4.3.8 Uranium Fuel Cycle Facilities, Uranium
failings, ligh-Level Waste Management 4-38
4.4 Uncertainties 4-41
5. RETUCTIOM OF DOSE AND RISE 5-1
5.1 Introduction 5-1
5.1.1 Emission Control technology 5«1
5.1.2 Work Practices 5-1
5,1,3 Impact of Existing Regulations on
Strategies for Reducing Emissions 5-2
5*2 Emission Control Technology 5-2
5.2.1 Scrubbers 5-3
5.2.2 Filters 5-4
5,2.3 Mechanical Collectors and Electrostatic
Precipltators 5-10
5-2.4 Charcoal Adsorbers 5-10
5.2.5 Miscellaneous Emission Control Equipment 5-13
5.3 Work Practices 5-15
5.4 Summary of Emission Reduction Strategies 5-18
5.5 Uncertainties in Evaluation of Control Technology
Efficiencies 5-18
tv
-------
CONTENTS (continued)
Fage
6. MOVEMENT OF MBICMJCLIDES THROUGH tSVXXORKEHXAL PATHWAYS 6-1
6.1 Introduction 6-1
6.2 Dispersion of Radiotmclides through the Mr 6-3
6.2.1 Introduction 6-3
6.2.2 Air Dispersion Models 6-6
6*2,3 Uncertainties in Atmospheric Dispersion
Modeling 6-8
6.3 Deposition on Atmospheric Badionuclides 6-9
6.3.1 Introduction 6-9
6,3.2 Dry Deposition Model 6-9
6.3.3 Vet Deposition Model 6-9
6.3,4 Soil Concentration Model 6-10
6.3.5 Uncertainties 6-11
6.4 Transport through the Food dials 6-11
6.4.1 Introduction 6-11
6.4.2 Concentration in Vegetation 6-12
6.4.3 Concentration in Meat and Milk 6-13
6,4.4 Summary • 6-14
6.5 Calculating the Environmental Concentration of
Radlonuclides: The AIRDOS-EPA Code 6-14
6.5.1 Introduction 6-14
6.5.2 AIlDOS-EtA . 6-15
7. RADIATION DQSIM1TII . 7-1
7*1 Introduction 7-1
7.2 Definitions 7-1
7.2.1 Activity 7-1
7.2.2 Exposure and Dose 7-2
7,2.3 'External and Internal Exposures 7-2
7.2.4 Dose Equivalent 7-3
7.3 Dosimetry Models 7-3
7.3.1 Internal Doses 7-3
7*3.2 External Doses 7-8
7.3*3 Effects of Decay froduct* 7-8
7.3.4 Dose Kate Estimates 7-9
7.4 EPA Dos* Calculation 7-9
7,4.1 Dose Rates 7-9
7,4.2 Exposure and Usage 7-10
7.5 Uncertainty Analysis 7-11
7,5.1 Dose Uncertainty Resulting from Indi-
vidual Variation 7-12
7,5.2 Dose Uncertainty Resulting from Age 7-14
7.5.3 Dose Uncertainty Caused by Measurement
Errors 7-23
7.6 Distribution of Doses in the General Population 7-23
7.7 Suwsary 7-29
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CONTENTS (continued)
Page
8. ESTIMATING THE RISK OF HEALTH EFFECTS RESULTING FROM RABIO-
NUC1IDE AIR EMISSIONS 8-1
8.1 Introduction 8-1
8,2 Cancer ftiak Estimates for Low-lET Radiation 8-3
8.2.1 Assumptions Heeded to Make ii.sk
Estimates 8-4
8.2,2 Dose Response Functions 8-4
8.2.3 The Possible Effects of Dose Rate on
Radiocarcinogenesis 8*6
8.2.4 Risk Projection Models 8-7
8.2.5 Effect of Various Assumptions on the
Numerical Risk Estimates 8-9
8,2,6 Comparison of Cancer Risk Estimates for
Lo*r-LET Radiation . 8-10
8,2.7 EPA Assumptions about Cancer Risks
Resulting from Low-LET Radiations 8-12
8.2.8 Methodology for Assessing th* Risk of
Radiogenic Cancer 8-13
8,2,9 Organ Risk* 8-14
8,2,10 Methodology for Calculating the Pro-
portion of Mortality Resulting
frea Leukemia 8-19
8.2,11 Canter Risks Hue to Age-Dependent Doses 8-20
8.3 Fatal Cancer Risk Resulting from ligh-LET Radiations 8-21
8,3.1 Quality Factors for Alpha Fartlcles 8-22
8.3.2 Dose Response Function 8-22
8.3.3 Assumptions Made fey EPA for Evaluating
the Dose from Alpha Particle Emitters 8-23
8,4 Estimating the Risk Resulting from Lifetime
Population ExposttfWfe-fcQB R«4on-222 Progeny 8-25
- • t»frfl - €h*r*c*uit lag Exposures to the General
3r ' Population vis-a-vis^Undergro^ftid
HiMrs ~ 8-26
8.4.2 The 1FA Modal 8-28
8.4,3 Comparison of iisfc Estimates 8-29
8,5 Uncertainties in Risk Estimates for Radiogenic
Cancer * 8-33
8.5.1 Uncertainty in dfe Dose Response Models
Resulting from Bias in the A-bomb
Dositjetty 8-33
8.5.2 Sampling fariation 8-3?
8,5.3 Uncertainties Arising from Model
Selection 8-3?
8.5.4 Suamary 8-39
8.6 Other Radiation-Induced Health Effects 8-41
8,6.1 Types of Genetic Harm and Duration of
Expression 8-41
vi
-------
CONTENTS (continued)
8.6.2 Estimates of Genetic Harm Resulting from
Low-LEf Radiations 8-44
8.1.3 Estimates of Genetic Harm for ligh-LET
Radiations 8-50
8.6*4 Uncertainty in Estimates of lUdiogenetic
Ham 8-50
8.6.5 The EPA Genetic Risk Estimate 8-54
8.6.6 Teratogenic Effects 8-56
8.6.7 Nocstochastic Effects 8-63
8.7 Radiation Risk - A Perspective 8-63
9. SUMMARY Of DOSE AND RISK ESTIMATES 9-1
9,1 Introduction 9-1
9,2 Doses and Risks for Specific Facilities , "• 9-2
9.3 Overall Uncertainties f-2
. . 9*3.1 Emission and Pathway Uncertainties 9-2
9.3.2 Cose Uncertainties 9-5
.-,. : -• • 9.3.3 .llsk teetrttintles , . ,r • . 9-5
f,3.4 Overall Uncertainty 9-5
Addendum A - Computer Codes Used by EPA to Assess Doses from . .
Radiation Exposure A-l
Addendum I - Mechanics of the Life Table Implementation of the
, ', c Risk Estimates • .• • • " i , B-l
vli
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Hadon-j22 ffgom PQE Facilities
o There ate about 5 facilities with radon-222 emissions
due to uranium ore residues remaining from the former
Manhattan Engineering District Sites,
o Major sites are the Fernald cite and the Monticello
tailings pile.
0 All sites will be assessed using site specific data.
o Source term data will be somewhat uncertain due to
fugitive emissions; control technology and cost data
good,
o This is new work.
Coal-fired Boilers
o There are about 1200 utility boilers, and tens of
thousands industrial boilers,
o Boilers will be characterized and grouped and model
boilers developed.
o Number of people at risk will be uncertain;
considerable exposure overlap is expected due to the
large number of boilers.
o Latest QAQPS data on risk and emissions to be used.
0 r a n i urn Fuel
o There are approximalty 100 major nuclear power
stations that require approximately 30 to 40 support
facilities o£ various kinds.
o Previous analysis in 1975 is obsolete.
o sites will be assessed based on models*
o Uncertainty is moderate due to model approach,
o This is new work.
-------
High-level Radioactive Haste
o HO facilities are in existence.
o Previous EPA work under Atomic Energy Act authority
judged sufficient.
o This category is given low level of effort.
Phosphogypsum files
o All sites (80) will be assessed using site specific
data.
o Data will be good; uncertainty moderate largely due to
uncertainty in emissions data.
o This is all nev work.
-------
For Each Source Category
T the extent possible, we will provide for each category
the following information:
* Individual fatal cancer risks based on site specific
meteorology, demographics, and
- The number of people at risk of fatal cancer by
range of risk and incidence.
- Feasibility and cost of controls and resulting risk
reduction.
- Health effects in addition to fatal cancer, to
the extent known.
- uncertainties.
-------
Agr««»tnt
Environmental fiottction Ajtncy
Office of ladlation Frogt**«
401 M St., SV
ViBhlntton ' DC 20660
U.S. D*part«*nt of £o«r§y
Oak Xtdf* Optt*tlon» Office
P.O. Box £ Oak tidf*. TN 37831
.
AtictiBcnt of li*k to Population of the U.S. from ladoa £vi«ti0ac froa
Stack*.
Christopher Welion (ANR-460)
Office of Radiation Progt»»*
Environ»«ot*l Prottcc ionAjency
Wiihinston, DC 20460 FTS 47S-I640
Frank 1. 0*Donne1
Oak tidg* National Laboratory, (450QS,
MS-102. P.O. Sox I
Oak iidta, TN 37131 FTS 626-2132
IQ ,
Jam 30,
l.
S«e Attached Scop* of Work
<9 ttatwiat* A«(M»itt i«v axft Tfwtttvr M
leeftOftv Arf of 1912&U.S. C. AftfJiK a
sendtd. Clean Air Act 19
u
7 Federal..
AMOUNT
Tm|
AMI *
-------
k Assignment 1-41, Cnange 1
Scope of Work Amendment
Section V. Scope o£ Work, under item 1 add the following:
The contractor shall prepare a detailed examination of cost
effectiveness for all control options for phosphogypsum
stacks. This shall include cost estimates using actual
data from representative stacks in the industry.
The contractor shall also prepare a-R*gulitosy Impact
Analysis (fctA) in support qf the culemaking activities for
phosphogypsum stacks. The^'llA shall include the industrial
profile prepared under WAl-41. In addition, the contractor
shall prepare an economic inpact analysis and a
cost-benefit analysis for all control options.
i
The -RIA shall also include summary discussions of emission
.levels, risk levels, feasible control options, and an
examination of the possible misuse of phosphogypsum and the
benefits of preventing this misuse. The" RIA shall also
include a Regulatory Flexibility Analysis. ThrJtIA shall
be of adequate scope and depth of analysis to support a
major rulemaking.
Section V. Scope of ttork, under item 4 add the following:
the contractor shall prepare an evaluation of the work
performed by other program offices within EPA as described
in WA 1-41.
* Economic Analysis Report Change
Sectio'.> VI. Reports is changed as follows:
Draft outline for EA chapters: 5 copies, 7 days after W.A.
Assignment Change 1 is issued,
Schedule foe EA chapters; same as above.
Draft EA: 20 copies, October 1, 198S
Final EA: 20 copies, December 1, 1988
-------
r
Chapter 3. Phosphogypsum Stacks
Scape of Work
Task 1: Risk'Estimates
The Contractor snail prepare a report, foe use in tne 3:2,
on the frequency distribution of nsfc levels from
Pnosphogypsurn scacks in the U.S. for use in the Background
Information Document (BID). The Contractor shall use
£PA-approved assessment models, such as ISC/LT, in
consultation witn tne Tas* Manager, to compute the
frequency distribution, as well as existing risk estimates
(using AIROOS/DARTA3) whicn are available from E£R?.
In preparing the report, the contractor shall address the
following technical issues;
1.1 Make adjustments foe the variation of radon decay product
equilibrium fraction as a function of distance. Current
estimates assume a constant 70% equilibrium fraction. This
adjustment will lower the% risk to populations within 20
kilometers of each stack."
1.2 Compute the correct number of people at each risk level for
Phosphogypsum stacks that are co-located. This will
involve the resolution of two problems; 1) Sumraing the
radon exposures to individuals from multiple piles, and 2}
correctly counting the populations exposed to each pile
without douole-counting those populations exposed to
multiple piles. The contractor shall examine the problem
of considering the varying equilibrium fractions to
individuals exposed to multiple sources at varying
distances and determine if a practible solution exists,
The contractor shall incorporate this solution in
consultation with the Task Manager.
1.3 Evaluate the effect of using an elevated height for the
radon release from 3 model phosphogypsum stack. Current
A1RD0S/DARTAB estimates used a ground level release on the
assumption that this would correctly account for the plume
downwash caused by the wake effect.
1.4 Make recommendations regarding the calculation of the
source term for phospnogypsun sticks. The current
estimates are based on half the flux for the top layer of
phosphofypsum, which accounts for the ponded area.
However, this does not account for the reduced flux on the
sides of the stack, which have crusted over and generally
have a flux about 20% of the top layer. Also* the
Contractor shall examine the effect of calculating the
source term based on flux characteristics averaged over the
lifetime of the stack.
-------
Task 2: Evaluation of Misuse of Phosphogyosum
Tne Contractor snail prepare a report for use in ti-,e BID
and RIA tftat examines* -.*.* potential for misuse of raater.al
in pftosphofypsw^ staco. Tr.is T=V ae a significant procle
foe stacks in Califorr,; $t wr-.lcr. reporcedr/ nave disappe
from oeir.c used for soil ;or.cxv»oner. Pnosphogypaur, ears
also DS misused foe zryw^Ii procu-ction. -Tnis report shall
-oe of sufficent scope and quality to support a Regulatory
Irapact Anilysis f or" r.ilaaa^ir.j activities involving an
industry cost of $100 r.illi-sn,
E s ti mat ed L_e ve.lr o f i: SJt f o,: r.
Task it 1000 iaooc -ours
TasK 2; 1000 laoor nc-r=
Schedu le_ and 6 Jt s
Draft Report; Jaly ., ;9S3, 5 copies
Final Report: August 1, 19SS, 5 copies
-------
-------
SCOPE OF WORK
Computer Science Corporation - Las Vegas
Contract I6S-01-7365-Q39
Title: DESIGN AND CODING OF AIRDOS-EPA, VERSION 2
Background;
The Criteria1and Standards Branch, DIP, needs to establish
an upgraded version of the codes used for dose and risk
estimation for standard-setting activities. These upgraded
code will incorporate the latest refinements in calculation
methodologies,, be more flexible and easy to use, and
generate output more immediately useful to Agency decision
makers. In order to make these modifications, the current
version of mainframe codes AIRDOS and OARTA3 require three
general modifications: incorporation of new assessment
methodologies, enhancement of input and output procedures,
and generation of presentation-quality graphics.
Description of Work:
A) 'Incorporation of New Assessment Methodologies:
Under the direction of EPA experts, the contractor shall modify
the existing mainframe AIRDQS/DARTAB codes to:
1) vary equilibrium fraction of radon decay products as a
function of distance.
2) Calculate "Effective Dose Equivalent" ac-ording to ICRP26
and 30 methodology.
3) Incorporate new dose and risk factors,
4} Recompile 'selected sections of code for more efficent
operation.
5} (tentative*) calculate national impacts of radon
6) {tentative*} Allow for multiple sources, not co-located.
7) (tentative*) Calculate building wake effects.
* Methodologies for items marked "tentative*1 are
presently being developed by the Bioeffects Analysis
Branch (BABJ, Coding of these items will require that
a satisfactory methodology be developed by BAB.
-------
B) Enhancement of Input and Output;
1) Set up the codes to run in full screen/interactive
fashion. The code should prompt the user to input data in
a straight-forward and logical manner* preferably using a
menu format similar to that used by the AIRDQS-PC cade.
The code shall be v'Eiy user-friendly and forgiving of
errors, if practicable* the code should run in real time
and not batch node. Assessments for individual facilities
should be easily accessible from a menu or directory, so
that a modified run can be easily made.
2) Allow the user to select meterologieal data from a menu.
Set up a data base of data sets that can be accessed
easily. Code an identification in each meterological data
set that will allow the program to identify the source of
the data and the proper format.
33 Allow the user to select from existing population grids or
generate new ones easily.
4} Refine output for each assessment such that it succinctly
summarizes inputf file names and important dose and risk
data. Be able to print out any and all location tables and
other output from a menu.
5) Have the code wake sure that distances -sleeted match the
population grid, if applicable. Set up to run population
and individual assessments at the same -ime (the codes must
now be ran separately to alter imported food fractions and
distances,}
6) Store ihe output from each run in a master data base that
will a.^iow for recalculation of doses and risks if the
factors* change, and to do graphical output summaries for
ALL assessments on demand (described later).
7) Generate output in three ways: for each facility that is
assessed, for all facilities in a source category, and
across all source categories. Categories will be further
broken down into Radon and Non-radon groups. There are now
a total of 11 source categories:
Non-Radon:
NEC licensees, DOE facilities, High Level Waste
Facilities, Uranium Fuel Cycle facilities, Elemental
Phosphorous Plants, Coal Fired Boilers.
Radon;
Underground and Open-Pit Uranium Mines, Active Mill
Tailings, Disposed Mill Tailings, Radon from DOE
facilities, Phosphogypsum piles.
-------
8) Include in the output for tach facility the following items:
a) Do a synopsis on just a few pages that summarizes
facility name, user input, date, run number, and file
names used and selected output. The selected output
should be the five highest organ doses and effective
dose equivalent for individual (mrem/vr) and
collective assessment {PR/YS5, the maximum individuals
lifetime risk, total fatal canctrs/yr, and a table
showing number of people at various risk levels. The
table of people/risk should be modified to include
total number of deaths/yr due to this risk or higher,
take the risk level down to 1E-10, and print risks in
x.x EXX format.
b) Plot isopleths of individual dose on a map of the
facility and surroundings (Scale to be determined).
Include population grid information on this plot, so
that approximate numbers of people at various doses
can be easily seen. Put- a legend at the bottom of the
graphic showing facility-name, scale, etc.
9) Include in the output for each source category the
following items:
a) show the number of facilities, total r^mber of people
at various risk levels, total population within 80 km
of all facilities (assuming no overlap), total fatal
cancers/yr, total effects/yr, the highest maximum
individual risk {and identify the facility with the
highest risk).
*
10} include in the output for a summary across all categories
the following items;
a) A summary of risks, showing the categories, number of
sources in each, highest individual risk, fatal
cancers/yr, and total population with 30 km.
b) The total number of people at various risk levels for
each category, arranged graphically so that all
categories can be easily compared in a visually
appealing manner. A grouping of 3-D colored
histograms may be appropriate here.
c) A graphical ranking of highest maximum individual risk
for all of the categories, with EPA-supplied
uncertainty bars around the risk points. The total
number of deaths/yr shall be incorporated in a
notation for each category.
-------
Item 10 (continued)
10) d) A repeat of the above with various dose standards
superimposed, to show the categories that would be
affected by various dose standards.
e) A repeat of the above that shows deaths/yr instead of
naximum individual dose.
f) (tentative*) National impacts of radjajo from fehe
assorted radon categories. •-*ps-4"
C) Graphics iackage: ""/' '
, „ .«rtllt,%.l • , j,__. • -Ittaii'.; \
' *,j]2J*J * ' ' *I ^2™. ._
Add capability to produce presentation-quality griphics
su»raarizing the dose and, risk assessments for facilities,
categories and across all categories to .be used by Agency
decision makers.
-------
Document 3436G
OUTPUT FOR AIRDOS-PLOS/MAINFRAME
ID No.:
Date/Time:_
Run No.:"
••- Facility:_
Address:.
city:
State?
ZIP
Source Category:_
COMMENTS:
Year:
INDIVIDUAL ASSESSMENT:
For RADON ONLY .'
Exposure in
.pCi/1 at that location
Lifetime Fatal Cancer Risk
POPULATION ASSESSMENT;
For RADON ONLY:
Exposure in Person-WLM/Yr
Total Fatal Cancers/Year
Location; _ SO0 meters North
ForNon-Radon;
Organ Doses in mrem/y
ICRP effective dose equivalent
Lifetime Fatal Cancer Risk
For Non-Radon:
Per son-Rent/Year
Total Fatal Cancers/Year
FREQUENCY DISTRIBUTION OF RISK- LEVELS:
Total in
Risk
interval
le-l to le-2
le-2 to le-3
le-3 to le-4
le-4 to le-5
le-5 to le-6
< le-6 tc le 7
-tfr—7 tti l6JS"8"""
la— A. t~n. lr 9
-3r Q (u Tp»in
Total in
Interval
XXX
XXX
XXX
XXX
XXX
XXX
XXX
XXX
— 5f1f¥
Interval
or Higher
xxxx
xxxx
xxxx
xxxx
xxxx
xxxx
xxxx
xxxx
1f**X
Fatal Cancers
per Year fro»
this Interval
xxxx
xxxx
xxxx
xxxx
xxxx
xxxx
xxxx
xxxx
xxxx
FC/Y from
this Interval
or Higher
xxxxx
xxxxx
xxxxx
xxxxx
xxxxx
xxxxx
xxxxx
xxxxx
xxxxx
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SITE INFORMATION:
MET data from:
Temperature:
Rainfall;
Mixing Height:
SOURCE TERM
Nuclicle
Page 2
Pocatello, Idaho 1965-1969
mm: HDR: CODE:
19 *C
11 cm/yr
1100 meters
SET:
Stack No:
Class AMAD 1 2
Area/Stack Height;
Area/Stack Diameter:
Plume Rise (units)j
POPULATION ARRAY: Latitude:
Longitude-: .
500
N XXXX
NNW XXXX
NW XXXX
W XXXX
WSW XXXX
SW XXXX
SSW XXXX
S XXXX
4,
DISTANCES
1000
XXXX
XXXX
XXXX
XXXX
XXXX
XXXX
XXXX
XXXX
USED
2000
XXXX
XXXX
XXXX
XXXX
XXXX
XXXX
XXXX
XXXX
«*
3000
XXXX
XXXX
XXXX
XXXX
XXXX
XXXX
XXXX
XXXX
4000
XXXX
XXXX
XXXX
XXXX
XXXX
XXXX
XXXX
XXXX
FOR MAKIMUM INDIVIDUAL
1000
XXXX
XXXX
XXXX
XXXX
XXXX
XXXX
XXXX
XXXX
10000
XXXX
XXXX
XXXX
XXXX
XXXX
XXXX
XXXX
XXXX
20000
XXXX
XXXX
XXXX
XXXX
XXXX
XXXX
XXXX
XXXX
30000
XXXX
XXXX
XXXX
XXXX
XXXX
XXXX
XXXX
XXXX
ASSESSMENT !
FOOD SUPPLY FRACTIONS:
POPULATION ASSESSMENT:
Local Regional Imported
Veg.: xxxx xxxx xxxx
Meat: xxxx xxxx xxxx
Milk; xxxx xxxx xxxx
REFERENCE FILE NAMES FOR ASSESSMENT:
INDIVIDQAL ASSESSMENT:
Local Regional Imported
xxxx xxxx xxxx
xxxx xxxx xxxx
xxxx xxxx xxxx
Prepar File: MGUCAAR._CAA88.ELSMPHOS(FMCCONCJ
STAR Array: MGUCAAR7CA¥IIVSTARL1B(XY28945)
Population: MGUCAAR.CAA88.POPLIB(POCATELL)
Radrisk File:CBNRAC5.CAA84.RADRISK.V'8'4Q1RBP
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page 3
Optional fables (selected by user)
Environmental Transport Variables:
(do as now printed in AIRDOS)
fraction of radioactivity retained after washing: .5
Infestion of Produce
Ingestion of ...
m 9 * *
Buildup time in soil
(consult with Barry on what variables to include? will decide
case-by-case!)
Radiqnuclide-specific environmental transport variables;
For each NUCLIBfi; ANLAM, Scavenging Coefficent, Deposition
velocity. Gravitational Settling Velocity»LAMSUR
Heterological Pata:
(Using a convention of wind PROM the direction and CLOCKWISE
ordering of directions): Arithmetic Average Wind Speeds, Wind
Rose, Harmonic Average Wind Speeds, Stability Array, Surface
Roughness length, Height of Wind Measurements (meters), Average
wind Speed
AGRICULTURAL ARRAYS:
as they currently appear in A1RDQS do NOT put in water arrays^
CHI/Q tables:
as they appear in AIROOS, but put direction and distances in
ENGLISH, not numbers!
CONCENTRATION TABLES;
Wind pCi/cu*meters Dry Dep* Gnd Dep.
Toward Distance Nuclide (not cm3M RATE RATE
North 5000 Po-210 2342 234 234
(deposition rates in terms of cubic meters, not centimeters)
Input values for Radionucljde-Independent Variables*
(as they now are printed in AIRDQS)
INPUT DATA FOR NUCLIDE XXXXX
as now printed in AIRDOS but DON'T print AIRDOS dose conversion
factors; include Buildup Factors and parents.
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4 ' *
page 4
Optional Tables (continued)
DOSS /RISK Conversion factors from SARTfti
(at present, units are not printed,* can w* put units in?)
Organ dose weighting factors used
POSE/RISK Location Tables (offer a logical menu here)
RN-222 Working i^evel Tables;
Equil.
Direct ion Distance Friction WLH
North 1000 .36 xxx xxxxx
(equilibrium fraction and WLM will have to be computed)
-------
Frequency Distribution of
Individual Risks
(total number
at this risk
or higher
otal number
at thts risk
or higher
10
Itf4 1Q'3
Elemental
Phosphorous
Plants
Active
Mill
Tailings
-------
Proposed
Standards:
500
mrem/y'
100
mrern/y
25
mrern/y
1
mrem/y
Elem. Umn.
Phos. Fuel
Cycle
NRC 001 . Coil
Fired
Boilers
10
rt
10
10
10
-------
•i * t
pCi/1
— M«ri:;;;:;-;»i:i
pCi/1
1
pCi/1
Tsiall
::•:
.-:;i*;*;»:»
•:-:«:-*'!-:
10
-2
Activt wnim ~ Open
Hill 9nwnd pn
Tailings Ur*nfllm Mines
Disposed Phospho- DOE
Mill Gypsum Radon
Tail inns Stacks
------- |