United States Office of Emergency and Publication 9285.7-09B
Environmental Protection Remedial Response ' PB92 - 963362
Agency Washington, DC 20460 May 1992
Superfund
Guidance for Data
Useability in Risk
Assessment (Part B)
Final
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9285.7-09B
May 1992
Guidance for Data Useability in
Risk Assessment
(Part B)
Final
Notice: This is a supplement to Guidance
for Data Useability in Risk Assessment -
Part A
Office of Emergency and Remedial Response
U.S. Environmental Protection Agency
Washington, DC 20460
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NOTICE
The policies and procedures set forth here are intended as guidance to U. S. Environmental Protection Agency and other
government employees. They do not constitute rulemaking by the Agency, and may not be relied on to create a
substantive or procedural right enforceable by any other person. The U.S. Environmental Protection Agency may take
action that is at variance with the policies and procedures in this guidance and may change them at any time without
public notice.
Copies of the guidance can be obtained from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Phone: 703-487-4650
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Contents
CHAPTER 1 INTRODUCTION AND BACKGROUND 1
1.1 CRITICAL DATA QUALITY ISSUES IN RISK ASSESSMENT 1
1.2 FRAMEWORK AND ORGANIZATION OF THE GUIDANCE 1
CHAPTER 2 THE RISK ASSESSMENT PROCESS 3
2.1 DATA COLLECTION AND EVALUATION 3
2.2 EXPOSURE ASSESSMENT 3
2.2.1 Identifying Exposure Pathways 3
2.2.2 Exposure Quantification 4
2.3 TOXICITY ASSESSMENT 4
2.4 RISK CHARACTERIZATION 5
2.5 ROLES AND RESPONSIBILITIES OF KEY RISK ASSESSMENT PERSONNEL 5
CHAPTER 3 USEABILITY CRITERIA FOR BASELINE RISK ASSESSMENTS 7
3.1 DATA USEABILITY CRITERIA 7
3.1.1 Data Sources 7
3.1.2 Documentation 7
3.1.3 Analytical Methods and Detection Limits 7
3.1.4 Data Quality Indicators 7
3.1.5 Data Review 8
3.2 PRELIMINARY SAMPLING AND ANALYSIS ISSUES 8
3.2.1 Radionuclides of Potential Concern 8
3.2.2 Tentatively Identified Radionuclides 9
3.2.3 Detection and Quantitation Limits 9
3.2.4 The Estimated Lower Limit of Detection 9
3.2.5 The Estimated Minimum Detectable Concentration 11
3.2.6 Media Variability Versus Measurement Error 11
3.2.7 Sample Preparation and Sample Preservation 11
3.2.8 Fixed Laboratory Versus Field Analysis 13
CHAPTER 4 STEPS IN PLANNING FOR THE ACQUISITION OF USEABLE
ENVIRONMENTAL DATA 17
4.1 STRATEGIES FOR DESIGNING SAMPLING PLANS 17
4.1.1 Determining the Number of Samples 17
4.2 STRATEGY FOR SELECTING ANALYTICAL METHODS 24
4.2.1 Selecting Analytical Laboratories 25
CHAPTER 5 ASSESSMENT OF ENVIRONMENTAL DATA FOR USEABILITY IN
BASELINE RISK ASSESSMENTS 29
in
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Contents
(Cont'd)
CHAPTER 6 APPLICATION OF DATA TO RISK ASSESSMENT 33
6.1 RADIONUCLIDES OF CONCERN 33
6.2 DISCRIMINATION OF SITE CONTAMINATION FROM BACKGROUND 33
6.3 EXPOSURE PATHWAYS 33
6.4 DOCUMENTATION OF ANALYTICAL PROCEDURES AND RESULTS 34
APPENDICES 37
I. GLOSSARY OF RADIATION CONCEPTS, TERMINOLOGY AND UNITS 39
II. RADIOACTIVE SUBSTANCES IN THE ENVIRONMENT 45
III. EPA RADIATION PROGRAM STAFF 65
REFERENCES 69
INDEX 71
IV
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Exhibits
1. Examples of Typical Minimum Detection Concentration (MDC) Values for Environmental Radioanalyses 10
2. Field Survey Instruments for Measuring Gamma Radiation 14
3. Survey Instruments for Measuring Alpha and Beta Radiation 15
4. Illustration of Bore-Hole Gamma Profiling 16
5. Hierarchical Structure of Sampling Design Selection Worksheet 18
6. Effect of Source Depth on Surface Gamma Radiation Measurements 23
7. Order of Priority for Selection of Analytical Methods 24
8. References for Radiochemical Procedures 25
9. Generalized Equations for Radioactivity Calculations 30
10. Generalized Equations for Radioactivity Decay and Ingrowth Correction Factors 31
11. Data Report Requirements for Typical Radiochemical Analysis 32
12. Radiochemical Quality Assurance Support Documentation 35
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Tips*
A health physicist or radiochemist should work with the risk assessor from the beginning of
the remedial investigation process, (page 1)
Field measurements must be made using instruments sensitive to the type of radioactivity
present, (page 13)
The shipper of radioactive material is responsible for ensuring that the recipient is authorized
to receive the shipped material and for compliance with all applicable shipping and labelling
regulations, (page 25)
* For further information, refer to the text. Page numbers are provided.
Vll
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PREFACE
This document is the second part (Part B) of the two-part
Guidance for Data Useability in Risk Assessment. Part
A, developed by the EPA Data Useability Workgroup,
provides guidance on the analytical data quality and
useability requirements needed for the cleanup of
hazardous waste sites under the Comprehensive
Environmental Response, Compensation, and Liability
Act of 1980 (CERCLA) as amended by the Superfund
Amendments and Reauthorization Actof 1986 (SARA).
Part B provides supplemental guidance to Part A on
planning and assessing radioanalytical data needs for
the baseline human health risk assessment conducted as
part of the remedial investigation (RI) process at sites
containing radioactive substances. PartB isnotastand-
alone document, and at all times it must be used in
conjunction with Part A.
This guidance is addressed primarily to the remedial
project managers (RPMs) who have the principal
responsibility for leading the data collection and
assessment activities that support the human health risk
assessment. It also should be of use to risk assessors
who must effectively communicate their data needs to
the RPMs and use the data provided to them. Because
of the special hazards and unique sampling and analysis
considerations associated with radioactive substances,
RPMs and risk assessors are strongly encouraged to
consult with a health physicist, radiochemist, or both,
starting at the beginning of the RI planning process. For
reference, a list of the EPA Headquarters, Regional and
Laboratory radiation program staff is provided in the
Appendices.
Comments on the guidance should be sent to:
Toxics Integration Branch
Office of Emergency and Remedial Response
401 M Street, SW (OS-230)
Washington, DC 20460
Phone: 202-260-9486
Or to:
Radiation Assessment Branch
Office of Radiation Programs
401 M Street, SW (ANR-461)
Washington, DC 20460
Phone: 202-260-9630
IX
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ACKNOWLEDGEMENTS
This document was prepared under the direction of Ruth Bleyler and Lisa Matthews of the Toxics Integration Branch
(TIB), and Anthony Wolbarst and Michael Boyd of the Office of Radiation Programs (ORP), all of EPA Headquarters.
Preparation of this document benefited greatly from the technical reviews and recommendations provided by the
following individuals, to whom we wish to express our sincere appreciation:
Donna M. Ascenzi
TomD'Avanzo
Michael S. Bandrowsk
William Bellinger
James Benetti
Jon Broadway
James J. Cherniack
Gregg Dempsey
Robert Dye
Robert S. Dyer
Lewis K. Felleisen
Paul A. Giardina
Gary V. Gulezian
Scott Hay
Gary Johnson
Milton W. Lammering
Jerry Leitch
Phil Nyberg
Collen Petullo
Lowell Ralston
Angela Short
Pat Van Leeuwen
Chuck Wakamo
Samuel T. Windham
Gail Wright
USEPA Region VI
USEPA Region I
USEPA Region IX
USEPA Region III
USEPA Region V
ORP National Air and Radiation Environmental Laboratory (NAREL)
USEPA Region I
ORP Las Vegas Facility
USEPA Region VII
ORP
USEPA Region III
USEPA Region II
USEPA Region V
SC&A Inc.
ORD/QAMS
USEPA Region VIII
USEPA Region X
USEPA Region VIII
ORP Las Vegas Facility
SC&A Inc.
USEPA Region II
USEPA Region V
USEPA Region IV
ORP National Air and Radiation Environmental Laboratory (NAREL)
USEPA Region VII
XI
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Chapter 1
Introduction and Background
This guidance provides supplemental information
regarding the useability of analytical dataforperforming
a baseline risk assessment at sites contaminated with
radioactivity. The reader should be familiar with the
guidance provided in Guidance for Data Useability in
Risk Assessment - Part A before proceeding with this
document. Although Part A focuses primarily on
chemical contamination, much of the information
presented also applies to the risk assessment process for
radioactive contamination. The guidance offered in this
document is intended as an overview of the key
differences between chemical and radionuclide risk
assessments, and not as a comprehensive, stand-alone
document to assess the risks posed by radionuclide
exposures. Part A of this guidance should be used side
by side with this document because of the many
references to information and exhibits found in Part A.
Ğ A health physicist or radiochemist should
work with the risk assessor from the
beginning of the remedial investigation
process.
There are special hazards and problems associated with
radioactivity contamination. Accordingly, it is
recommended that a professional experienced in
radiation protection and measurement (health physicist
or radiochemist) be involved in all aspects of the risk
assessment process from the beginning of the remedial
investigation/feasibility study.
Additional information on important aspects of radiation
protection and measurement is provided in the
appendices. These appendices are included to provide
greater detail on topics presented in this guidance and to
facilitate a comprehensive understanding for the
interested reader. Appendix I is a glossary of terms that
apply to radioactivity. Appendix II is a discussion on
naturally occurring radionuclides and their presence in
the environment. Appendix III provides a list of the
names and addresses of the EPA Regional, Laboratory,
and Headquarters Radiation Program staff for health
physics and radioanalytical support.
1.1 CRITICAL DATA QUALITY ISSUES
IN RISK ASSESSMENT
The five basic environmental quality issues discussed in
Part A Section 1.1 also apply to radioactive
contamination. Specifics for data sources, detection
limits, qualified data, background samples, and
consistency in sample collection will be discussed later
in this guidance.
1.2 FRAMEWORK AND ORGAN-
IZATION OF THE GUIDANCE
This document is organized the same as Part A. Part A,
Exhibit 2 describes the organization of this document.
The assessment of radioanalytical data as opposed to
chemical data is emphasized.
This guidance discusses the data collection and
evaluation issues that affect the quality and useability of
radioanalytical data for baseline human health risk
assessments. Part A, Exhibit 3 lists the four components
of the risk assessment process and the information
sought in each of the components.
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Chapter 2
The Risk Assessment Process
This chapter discusses the data collection and evaluation
issues that affect the quality and useability of
radioanalytical data for baseline human health risk
assessments. Part A, Exhibit 3 lists the four components
of the risk assessment process and the information
sought in each of the components.
2.1 DATA COLLECTION AND
EVALUATION
Part A, Section 2.1.1 contains an overview of methods
for data collection and evaluation that can be applied to
sites contaminated with radioactivity as well as with
chemical hazards. The development of data quality
objectives as part of a carefully designed sampling and
analysis program will minimize the subsequent need to
qualify the analytical data during the data analysis
phase. Specific radioanalytical methods are described
in Section 3.0 of this guidance, along with a discussion
of chemicals of concern in Section 3.2. Strategies for
selecting analytical methods and designing sampling
plans can be found in Section 4.0.
2.2 EXPOSURE ASSESSMENT
The approach to risk assessment for radionuclides shares
the objectives stated in Part A, Section 2.1.2:
Identify or define the source of exposure.
Define exposure pathways (receptors) including
external exposure.
Identify potentially exposed populations.
Measure or estimate the magnitude, duration, and
frequency of exposure to site contaminants for
each receptor (or receptor group).
Exposure pathways should be designated before the
design of sampling procedures.
2.2.1 Identifying Exposure Pathways
This section describes a methodology for estimating the
radiation dose equivalent to humans from exposure to
radionuclides through all pertinent exposure pathways.
These estimates of dose equivalent can be compared
with radiation protection standards and criteria, with an
important cautionary note. These standards have been
developed for regulating occupational exposure for
adults and are not completely applicable to assessing
risk for the population at large. Section 2.4 describes a
methodology for estimating health risk.
Part A, Section 2.1.2 describes the procedures for
exposure assessment for chemical contaminants, and
many aspects of this section apply directly to
radionuclides. However, the term "exposure" has a
specific meaning for radionuclides which is distinct
from its use with chemical contamination (see Appendix
I). For chemicals, exposure usually refers to the intake
of the toxin (e.g., inhalation, ingestion, dermal exposure)
expressed in units of mg/kg-day, the same units used for
toxicity values. Unlike chemical toxins, an exposure
assessment for radionuclides can include an explicit
estimate of the radiation dose equivalent.
Inhalation and ingestion remain as important exposure
pathways forradionuclides, although the units to express
intake are in activity (i.e., Bq or Ci) rather than mass.
Radionuclides entering through these pathways may
become incorporated within the body where they emit
alpha, beta or gamma radiation providing internal
exposure to tissues or organs. Absorption is not an
important exposure pathway for radionuclides. Dose
equivalent is a quantity that incorporates both the energy
deposited internally from ionizing radiation and the
effectiveness of that radiation to causebiological damage
to the organism. The dose equivalent was developed to
normalize the unequal biological effects produced from
equal absorbed doses of different types of radiation (i.e.,
alpha, beta, or gamma).
Radionuclides need not be taken into or brought in
contact with the body to produce biological damage.
High energy emissions of beta particles and photons
from radionuclides can travel long distances with
minimal attenuation, penetrate the body, and deposit
their energy in human tissues. External radiation
exposures can result from either exposure to
radionuclides at the site area or to radionuclides that
have been transported from the site to other locations in
the environment. Potential external exposure pathways
to be considered include immersion in contaminated air
or water and direct exposure from ground surfaces
contaminated with beta- and photon-emitting
radionuclides. Gamma and x-rays are the most
penetrating of the emitted radiations and comprise the
primary contribution to the radiation dose from external
Acronyms
DCF dose conversion factor
EPA U.S. Environmental Protection Agency
HEAST Health Effects Assessment Summary Tables
IRIS Integrated Risk Information System
RPM remedial project manager
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exposures. External exposure to beta particles primarily
imparts a dose to the outer layer skin cells, although
high-energy beta radiation can penetrate into the human
body. Alpha particles are not sufficiently energetic to
penetrate the outer layer of skin and do not contribute
significantly to the external dose.
The amount of energy deposited in living tissue is of
concern because the potential adverse health effects of
radiation are proportional to the energy deposited. The
energy deposited is a function of a radionuclide' s decay
rate, not its mass. Therefore, as mentioned earlier,
radionuclide quantities and concentrations are expressed
in units of activity.
Environmentally dispersed chemicals, stable and
radioactive, are subject to the same processes that affect
their transfer rates and therefore their bioaccumulation
potential. Radionuclides undergo radioactive decay. In
some respects, this decay can be viewed as similar to the
chemical or biological degradation of organic
compounds. Both processes change the quantity of the
hazard present in the environment and produce other
substances. The products of radioactive decay may also
be radioactive and can contribute significantly to the
radiation exposure. These radioactive decay products
must be considered for risk assessment purposes.
2.2.2 Exposure Quantification
One of the objectives stated for exposure assessment
was to make a reasonable estimate of the maximum
exposure to receptors or receptor groups. The equation
presented in Part A, Exhibit 7 to calculate intake for
chemicals can be applied to exposure assessment for
radionuclides, except that the body weight and averaging
time terms should be omitted from the denominator.
However, exposures to radionuclides include both
internal and external exposure pathways, and radiation
exposure assessments take the calculation an additional
step in order to estimate radiation effective dose
equivalent which is directly translatable to risk.
Radionuclide intake by inhalation and ingestion is
calculated in the same manner as chemical intake except
that it is not divided by body weight or averaging time.
Forradionuclides.areferencebodyweightandaveraging
time are already included in the dose conversion factors
(DCFs), and the calculated dose is an expression of
energy deposited per gram of tissue.
External exposures may be determined by monitoring
and sampling of the radionuclide concentrations in
environmental media, by direct measurement of radiation
fields using portable instrumentation, or by mathematical
modeling. Portable survey instruments that have been
properly calibrated can display dose rates (e.g., Sv/hr or
mrem/hr), and dose equivalents can be estimated by
multiplying the dose rate by the duration of exposure to
the radiation field. Alternatively, measured or predicted
concentrations in environmental media may be
multiplied by DCFs, which relate inhaled or ingested
radionuclide quantities to effective dose equivalent.
Federal Guidance Report No. 11 (EPA 1988) provides
DCFs for each of over 700 radionuclides for both
inhalation and ingestion exposures, as well as immersion
exposures to tritium and the principle radioactive noble
gases. It is important to note that these DCFs were
developed for regulation of occupational exposures to
radiation and may not be appropriate for the general
population. The Integrated Risk Information System
(IRIS) (EPA 1989) and the Health Effects Assessment
Summary Tables (HEAST) (EPA 1990) provide slope
factors for radionuclides of concern for each of the three
major exposure pathways (inhalation, ingestion, and
external exposure) that may be applied to determining
the risk to the general population.
The dose equivalents associated with external and
internal exposures are expressed in identical terms (i.e.,
Sv), so that contributions from all pathways can be
summed to estimate the total effective dose equivalent
value and prioritize risks from different sources. A
more extensive discussion of quantifying exposure from
radioactivity can be found in RiskAssessment Guidance
for Superfund: Volume I, Human Health Evaluation
Manual, Part A, "Baseline Risk Assessments" (EPA
1991).
The radiation exposure assessment should include a
discussion of uncertainty. This should include, at a
minimum, a tabular summary of all values used to
estimate exposures and doses, and a summary of the
major assumptions used in the assessment process.
Special attention should be paid to the three sources of
uncertainty listed below:
Correlation of monitoring data and the actual
conditions on site.
Exposuremodels, assumptions, and input variables
used for the exposure estimate.
Values of variables used to estimate intakes and
external exposures.
2.3 TOXICITY ASSESSMENT
The objectives of toxicity assessment are to evaluate the
inherent toxicity of the compounds under investigation,
and to identify and select toxicological measures for use
in evaluating the significance of the exposure. Certain
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fundamental differences between chemicals and
radionuclides somewhat simplify toxicity assessment
forradionuclides.
Theoretically, any dose of radiation, no matter how
small, has the potential to produce adverse effects, and
therefore, exposure to any radioactive substance is
hazardous. A large body of data derived from human
and experimental animal studies establishes the principal
adverse biological effects of exposure to ionizing
radiation to be carcinogenicity, mutagenicity, and
teratogenicity. EPA's current estimates of adverse
effects associated with human exposure to ionizing
radiation indicate that the risk of cancer is limiting and
may be used as the sole basis for assessing the radiation-
related human health risks of a site contaminated with
radionuclides.
The dose-response assessment for radionuclides is also
more straightforward, and this relationship is relatively
well characterizedathigh doses. Accordingly, a detailed
toxicity assessment for individual radionuclides at each
site is not required. In general, radiation exposure
assessments need not consider acute toxicity effects
because the quantities of radionuclides required to
cause adverse effects from acute exposure are extremely
large and such levels are not normally encountered at
Superfund sites.
2.4 RISK CHARACTERIZATION
The final step in the risk assessment process is risk
characterization. This is an integration step in which the
risks from individual radionuclides and pathways are
summed to determine the likelihood of adverse effects
in potentially exposed populations. Since the concern
is for radiation dose equivalent, and since all pathway
doses are calculated in comparable units, the total
effective dose equivalent from all pathways is easily
computed and can be translated directly to risk.
All supporting documentation provided for the exposure
assessment should be compiled to ensure that it is
sufficient to support the analysis, to allow an independent
duplication of the results, and to ensure that all exposure
pathways have been addressed. Additionally, all
assumptions regarding site conditions, environmental
transfer factors, etc., must be carefully reviewed to
ensure that they are applicable.
Once all data are in order, the next step is to calculate the
risk based on the estimated committed effective dose
equivalents. As stated earlier, risk assessment for
radionuclides needs to be considered only for the end
point of radiation carcinogenesis.
2.5 ROLES AND RESPONSIBILITIES
OF KEY RISK ASSESSMENT
PERSONNEL
The key risk assessment personnel and their
responsibilities are discussed in Part A, Section 2.2. It
is recommended that a health physicist or radiochemist
be involved in the risk assessment process to provide
technical assistance to the remedial project manager
(RPM) and the risk assessor. For a listing of EPA health
physics and radiochemical support staff, see Appendix
III.
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Chapter 3
Useability Criteria for Baseline Risk Assessments
This chapter discusses data useability criteria and
preliminary sampling and analysis issues. This
information can be used to plan data collection efforts
in order to maximize the useability of environmental
radioanalytical data in baseline risk assessments.
3.1 DATA USEABILITY CRITERIA
The data useability criteria presented in Part A, Section
3.1 are generally applicable to analytical data required
for baseline risk assessment, including radioanalytical
data.
3.1.1 Data Sources
The data source considerations given in Part A, Section
3.1.1 also apply to radioactively contaminated sites.
Since radioactive contamination can often be detected
in the survey process, preliminary assessment/site
inspection (PA/SI) and any other field measurements
may be of particular importance. Field measurements
that provide data for external exposure rates, while
usually considered screening, can be used for risk
assessment purposes directly, provided they meet the
data useability requirements. Also of potential
importance are the operating history of the site, handling
and disposal manifests, and U.S. Nuclear Regulatory
Commission (USNRC) licenses or state agency permits
regulating the possession of radioactive materials.
3.1.2 Documentation
The four major types of documentation discussed in
Part A, Section 3.1.2 apply equally to radionuclides:
Sampling and analysis plan (SAP) and quality
assurance project plan (QAPjP).
Standardoperatingprocedures(SOPs), particularly
those for the calibration and use of all field survey
instruments.
Field and analytical records, including all survey
information relating to radiation or radioactivity
concentrations.
Chain-of-custody records.
3.1.3 Analytical Methods and
Detection Limits
The importance of selecting proper analytical methods
based on detection limits that meet risk assessment
requirements is discussed for chemical analyses in Part
A, Section 3.1. A discussion of detection limits for
radiation detection instruments can be found in Section
3.2. A strategy for selecting radioanalytical methods
that meet risk assessment requirements is described in
Section 4.2.
3.1.4 Data Quality Indicators
Data quality indicators are the performance
measurements of dataquality objectives (DQOs). These
obj ecti ves should be a function of the desired confidence
level of the risk assessment and not based on the
availability or capability of specific analytical methods.
DQOs must be clearly defined for all radiation and
radioactivity measurements.
Quantitative data quality indicators for radioanalytical
measurements may include a lower limit of detection,
minimum detectable concentration, precision, accuracy,
and completeness. Qualitative data quality indicators
can be expressed as goals but cannot be demonstrated
quantitatively. Such qualitative data quality indicators
might include representativeness and comparability.
In setting DQOs, the relationship to the decision-making
process is paramount. The primary rationale for setting
DQOs is to ensure that the data will be of sufficient
quality to support the planned decisions and/or actions
to be taken based on those data.
The DQO process involves three stages: defining the
decision, reviewing the existing data to determine what
new data are required, and designing the sampling and
analytical program to obtain the required data. Data
Acronyms
CLP Contract Laboratory Program
DOT U.S. Department of Transportation
DQO data quality objective
EPA U.S. Environmental Protection Agency
G-M Geiger-Muller
HP health physics
IDL instrument detection limit
LLD lower limit of detection
MDC minimum detectable concentration
PA preliminary assessment
PC pressurized ion chamber
QAPjP quality assurance project plan
QC quality control
RPM remedial project manager
SAP sampling and analysis plan
SI site inspection
SOP standard operating procedure
SQL sample quantitation limit
TCL Target Compound List
TIC tentatively identified compound
USNRC U.S. Nuclear Regulatory Commission
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quality will be a function of the chemical preparation,
measurement system, selection of sampling and counting
parameters, and the control limits set for the data quality
indicators. After the establishment of the isotope-
pathway combinations of interest, the risk assessor
must develop the maximum uncertainties that can be
tolerated in the assessment of the activity for an isotope
in each media. These parameters define the data quality
indicators which in turn determine the available
procedures.
3.1.5 Data Review
While the RPM or other personnel can perform many
aspects of basic data re view, an individual experienced
in radiochemistry or health physics must perform the
detailed technical review of both the field and laboratory
data. Such a review should be performed on preliminary
data as they are collected and should continue throughout
the risk assessment process.
Special attention must be paid to all reports prepared by
datareviewers to ensure that there is anarrative summary
in addition to the data summary tables provided. The
additional, clarifying information in the narrative
summary will be of particular importance to reviewers
unfamiliar with radioanalytical data.
3.2 PRELIMINARY SAMPLING AND
ANALYSIS ISSUES
A discussion of issues affecting sampling and analysis
for baseline risk assessment is beyond the scope of this
document. A framework of key issues, tools, and
guidance used in the design and assessment of
environmental sampling and analysis procedures is
described in Part A, Section 3.2. This section
concentrates on the differences between sampling and
analysis for radioactive contamination compared to
sampling and analysis for chemical contamination.
3.2.1 Radionuclides of Potential
Concern
EPA classifies all radioactive substances as Class A
carcinogens (i.e., known human carcinogens). Any
radioactive substance detected or suspected of being
present at or released from a site will be considered to
be of potential concern and evaluated accordingly. The
risk assessor should review the list of radionuclides of
concern for each migration pathway. These lists should
contain the following information for each radionuclide
listed (see Appendix I for a more detailed discussion of
each of the factors):
Atomic number and atomic weight. The elemental
identity of a radioisotope is determined by the number
of protons in its nucleus (i.e., its atomic number), and its
isotopic identity is determined by the total number of
protons plus neutrons (i.e., its atomic weight). For
example, plutonium has an atomic number of 94.
Isotopes of plutonium, such as Pu-238, Pu-239, Pu-240,
Pu-241, and Pu-242, have identical atomic numbers but
different atomic weights. The origin, use, isotopic
abundance, radioactive (and perhaps physical)
properties, and cancer potency of each plutonium isotope
are unique. Thus, it is imperative that each radionuclide
be properly identified.
Radioactive half-life. The radioactive half-life of a
radioisotope is the time required for the activity of that
isotope to be reduced by one half. Half-life is a unique
characteristic of each radioisotope and is notaffectedby
chemical or physical processes. Knowledge of the half-
life of a radioisotope is important for the following
reasons:
The half-life determines the activity and cancer
potency of the isotope.
The half-life affects holding times for analyses
(radionuclides with shorter half-lives must be
analyzed in a shorter time frame than longer-lived
radionuclides).
The half-life determines the degree of activity
equilibrium between decay products (radionuclides
in equilibrium maintain equal levels of
radioactivity, if me equilibrium is disturbed the
activity levels of the progeny need to be measured
separately).
Principal decay modes, radiation decay modes,
energies, and abundances. Radioisotopes emit
radiation in the form of alpha, beta, and neutron particles,
as well as gamma photons and x-rays. The type,
abundance, and energies of the radiations emitted by a
radioisotope are unique to that isotope. Consequently,
the selection and use of sampling and analysis
procedures, radiochemical methods, and radiation
detection ins truments must be consistent with the decay
mode (i.e., alpha, beta, neutron, orphoton) andradiation
energies and abundances of the radionuclide of concern.
Chemical and physical forms. The mobility,
bioaccumulation, metabolic behavior, and toxicity of a
radioisotope are governed by its chemical and physical
form, not by its radioactive properties. Radioisotopes in
the environment may exist as solids, liquids, or gases in
a variety of chemical forms, oxidation states, and
complexes. Information should be provided in the data
package describing the most likely chemical andphysical
form(s) of each radionuclide at the time of production,
disposal, release, and measurement.
Decay products. Radioactive decay of an isotope of
one element results in the formation of an isotope of a
different element. This newly formed isotope, the
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decay product, will possess physical and chemical
properties differentfrom the parentisotope. Forexample,
Ra-226 may be present as a solid in the form of radium
sulfate while its daughter Rn-222 is a noble gas. Often,
a decay product is also radioactive and decays to form
a different radioisotope. It is important to consider all
radioisotopes for the following reasons:
The total activity content (and thus, the potential
hazard) of a radioactive source or sample may be
underestimated if progeny are excluded.
An isotope's progeny may be more toxic, either
alone or in combination, than the parent
radioisotope. For example, Ra-226 decays to Rn-
222 by alpha particle emission with a half-life of
1600 years, while Rn-222 and its daughters emit
three additional alpha particles and two beta
particles through the principle decay modes with
a combined half-life of less than four days.
The environmental transport, fate, and
bioaccumulation characteristics of the progeny
may be substantially different from those of the
parent isotope.
The siterecords, including the operating history, handling
and disposal manifests, andradioactivematerials licenses
or permits, will be useful in determining if the initial list
of radionuclides of concern derived from these records
and those radionuclides identified in media samples are
consistent. All omissions or inconsistencies in the
expected versus the observed radioisotopes at the site
should be noted, and additional information should be
sought to explain these discrepancies.
At sites containing both radioactive and other hazardous
substances, the list of chemicals of concern should be
reviewed for each sample medium for consistency and
completeness. The manner in which radioactive
substances are associated with nonradioactive hazardous
substances on the site should be described by the RPM
or risk assessor, to the extent that such information is
available. This description also should include a
discussion of the possible effects that these chemicals
may have on radionuclide mobility and bioaccumulation.
3.2.2 Tentatively Identified
Radionuclides
Because radionuclides are not included on the Target
Compound List (TCL), they may be classified as
tentatively identified compounds (TICs) under Contract
Laboratory Program (CLP) protocols. In reality,
however, radioanalytical techniques are sufficiently
sensitive that the identity and quantity of radionuclides
of potential concern at a site can be determined with a
high degree of confidence. In cases where a
radionuclide's identity is not sufficiently well-defined
by the available data set: (1) further analyses may be
performed using more sensitive methods, or (2) the
tentatively identified radionuclide may be included in
the risk assessment as a contaminant of potential concern
with notation of the uncertainty in its identity and
concentration. Ahealthphysicistorradiochemistshould
review the identification of any radionuclide to determine
if the radionuclide is actually present or is an artifact of
the sample analysis.
3.2.3 Detection and Quantitation
Limits
The terms used to describe detection limits for
radioanalytical data are different than the terms used for
chemical data. Detection limits must be specified by the
equations and confidence limits desired as well as being
defined numerically. Normally, detection limits will be
requested as the detection limits with a 5% chance each
of Type I and Type II errors. Exhibit 1 lists typically
achievable sensitivity limits for routine environmental
monitoring.
In order to satisfy these purposes, two concepts are
used. The first level is an estimated detection limit that
is related to the characteristics of the counting instrument.
This limit is not dependent on other factors in the
analytical method or the sample characteristics. The
limit, termed the lower limit of detection (LLD), is
analogous to the instrument detection limit (IDL). The
second limit corresponds to a level of activity that is
practically achievable with agiven instrument, analytical
method, and type of sample. This level, termed the
minimum detectable concentration (MDC), is analogous
to the sample quantitation limit (SQL) and is the most
useful for regulatory purposes.
3.2.4 The Estimated Lower Limit of
Detection
The LLD may be defined on the basis of statistical
hypothesis testing for the presence of activity. This
approach is common to many authors and has been
described extensively (Pasternack and Harley 1971,
Altshuler 1963, Currie 1968, NCRP 1978).
The LLD is an a priori estimate of the detection
capabilities of a given instrument system. This limit is
based on the premise that from a knowledge of the
background count and measurement of system
parameters (e.g., detection efficiency), an a priori limit
can be established for a particular measurement. The
LLD considers both the a and P errors. In statistical
hypothesis testing, a and p are the probabilities for what
are frequently referred to as Type I (false detection) and
-------
EXHIBIT 1. EXAMPLES OF TYPICAL MINIMUM DETECTION CONCENTRATION
(MDC) VALUES FOR ENVIRONMENTAL RADIOANALYSES*
Approximate
Media Sample Size
Soil 200
200
200
10
10
10
10
Water 50
4
4
1
1
1
1
1
Air 300
300
300
300
300
300
300
Biota 1000
1000
1000
1000
1000
1000
1000
grams
grams
grams
grams
gram
gram
gram
mis
liters
liters
liter
liter
liter
liter
liter
m3
m3
m3
m3
m3
m3
m3
g (ash)
g (ash)
g (ash)
g (ash)
g (ash)
g (ash)
g (ash)
Isotope
137Cs
60Co
226Ra
90Sr
U Isotopes
Th Isotopes
Pu Isotopes
3H
137Cs
60Co
226Ra
90Sr
U Isotopes
Th Isotopes
Pu Isotopes
137Cs
60Co
226Ra
90Sr
U Isotopes
Th Isotopes
Pu Isotopes
137Cs
60Co
226Ra
90Sr
U Isotopes
Th Isotopes
Pu Isotopes
MDC
1
1
0.1
1
0.1
0.1
0.1
400
1
1
0.1
1
0.1
0.1
0.1
0.01
0.01
0.01
0.05
0.0002
0.0002
0.0002
1
1
1
1
0.1
0.1
0.1
Reporting
Units Method'
pCi/g (dry)
pCi/g (dry)
pCi/g (dry)
pCi/g (dry)
pCi/g (dry)
pCi/g (dry)
pCi/g (dry)
pCi/L
pCi/L
pCi/L
pCi/L
pCi/L
pCi/L
pCi/L
pCi/L
pCi/m3
pCi/m3
pCi/m3
pCi/m3
pCi/m3
pCi/m3
pCi/m3
pCi/Kg (wet)
pCi/Kg (wet)
pCi/Kg (wet)
pCi/Kg (wet)
pCi/Kg (wet)
pCi/Kg (wet)
pCi/Kg (wet)
1
1
1
2
3
3
3
4
1
1
5
2
3
3
3
1
1
5
2
3
3
3
1
1
1
2
3
3
3
* For purposes of illustration only. Actual MDCs for listed radionuclides in the media shown will vary,
depending on sample specific preparation and analytical variables.
a) Methods
1 = High Resolution Gamma Spectrometry
2 = Chemical Separtion followed by Gas Proportional Counting
3 = Chemical Separation followed by Alpha Spectrometry
4 = Liquid Scintillation Counting
5 = Radon Emanation
CE1-002-76
10
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Type II (false non-detection) errors, respectively. A
common practice is to set both risks equal and accept a
5% chance of incorrectly detecting activity when it is
absent (a=0.05) and a95% confidence that activity will
be detected when it is present (1 - p = 0.95). The
expression for the LLD becomes:
LLD = K * (4.65 * sb)
where:
K = the proportionality constant relating the detector
response (counts) to the activity, such as K=l/e,
where e is an overall detection efficiency or K=l/
IteT where IT is the photon emission probability
per disintegration and eT is the detection efficiency
for the photon
sb = theestimatedstandarddeviationofthebackground
count (assumed to be equal to the standard
deviation of the sample count near the LLD)
3.2.5 The Estimated Minimum
Detectable Concentration
The MDC is a level of activity at which detection can be
achieved practically by an overall measurement method.
As distinguished from the LLD, the MDC considers not
only the instrument characteristics (background and
efficiency), but all other factors and conditions that
affect the measurement. The MDC is also an a priori
estimate of the activity concentration that can be achieved
practically under a set of typical measurement conditions.
These conditions include sample size, net counting
time, self-absorption and decay corrections, chemical
yield, and any other factors that comprise the activity
concentration determination. The MDC is useful for
establishing that some minimum overall measurement
conditions are met. Any of several factors, such as
sample size or counting time, may be varied to meet a
specific MDC value. Exhibit 1 lists typical MDCs for
radionuclides in several media.
Expressions for the MDC are similar to those for the
LLD. For the MDC, the proportionality constant K
would include not only the factors for the LLD but also
the factors that relate the detector response (counts) to
the activity concentration in a sample for a typical set of
measurement conditions.
3.2.6 Media Variability Versus
Measurement Error
Sampling and analysis variability and measurement
error are two key issues involved in planning and
assessing data collection efforts. Part A, Exhibit 31 lists
field quality control (QC) samples that are used in
defining variation and bias. These QC sample types
have similar purposes for radioactively contaminated
samples with one exception. The trip blank is not
required for radioactively contaminated samples because
there is less likelihood of contamination from direct
exposure to air than for samples of volatile organic
chemicals. Confidence level, power, and minimum
detectable relative difference are defined in Part A,
Section 4.1, and these definitions also apply in
radionuclide sampling.
3.2.7 Sample Preparation and
Sample Preservation
Proper sample preparation and preservation are essential
parts of any radioactivity sampling program. The
sampling requirements must be specified in the SAP
before sampling activities begin. Precise records of
handling are required to ensure that data obtained from
different locations or time frames are correctly compared.
The appropriateness of sample preparation is a function
of the required analysis. Some examples of sample
treatment to be avoided or performed with great care
include:
Aliquots of samples selected for H-3 should not be
dried, ashed or acidified.
Aliquots of samples selected for C-14 should not
be ashed or leached with acid.
Aliquots of samples selected for elements with
volatile oxidized forms, such as Iodine, should not
be treated with oxidizing acids.
Aliquots of samples selected for Ra-226 analysis
by gamma spectrometry should be dried, crushed
and/or sieved, but an appropriate post-preparation
holding time must be included to allow the
attainment of equilibrium with radon daughters.
Aliquots of samples selected for elements with
volatilized forms at high temperatures (e.g., I, Cs,
Ru) should not be ashed, or ashed with great care.
A radiochemist or health physicist should be
consulted on the proper handling of the samples
from a specific site.
The requirements of sample preservation are determined
by the required analysis as well as the chemical
characteristics of the radionuclide to be analyzed. The
purpose of preserving a sample is to maintain the
11
-------
sample in the condition required for analysis between
the time the sample is collected and the time the sample
is analyzed. Many of the radiochemical species of
interest behave like trace metals, and the preservation of
water samples is easily achieved by acidification. This
prevents metallic species from depositing on the walls
of the container. Usually, nitric acid is used to maintain
a pH of less than 2.0. Water samples preserved in this
manner have a holding time of six months. The
exceptions to this general rule are given below:
Samples for H-3 and C-14 analysis should be
unpreserved.
Samples for analysis of elements with volatile
oxidized forms (e.g., 1-129,1-131) should not be
preserved with oxidizing acids.
Certain laboratories may require samples for
uranium analysis to be preserved with hydrochloric
acid.
The container material for stored samples can also be a
factor in sample preservation. Metals have an affinity
for glass when preserved with nitric acid. Iodine and
transition metals such as iron and cobalt have shown an
affinity for polyethylene and polypropylene under certain
conditions (Bernabee 1980). The selection of containers
for different sample types should be specified in the
SAP.
Soil samples are generally collected and shipped to the
analytical laboratory "wet," meaning their inherent
moisture has not been deliberately removed. The SAP
should address the questions regarding if, how (air or
oven), and when (prior to or after aliquotting) the
sample will be dried. Often, a soil sample contains
much extraneous matter, e.g., rootmatter, rocks, stones,
organisms. The question arises whether these
"extraneous" materials are just that, or whether they
constitute part of the sample itself. These issues should
be specified in the analytical program design, and the
risk assessor must ensure that sample preservation has
not compromised the sample's integrity.
Samples of contaminated structural samples may be
collected at some sites. For structural material the data
may be reported as fixed or as removable contamination.
Fixed contamination refers to contamination that is
incorporated in the material or is firmly bound on the
surface of the material. Fixed contamination is measured
by cleaning the surface of the material and using a field
survey instrument to measure the activity of the material.
Removable contamination is contamination that can be
transferred from the surface of the material to another
object. Removable contamination is measured by
smearing the surface of the material with a small piece
of paper or cloth and measuring the amount of activity
on the smear. Special handling and analysis procedures
for these types of samples should be included in the
SAP.
The presence of radioactive and hazardous chemical
wastes (mixed wastes) at a site can influence the quality
of the analytical data obtained for that site. Two general
areas are affected by the special considerations of mixed
wastes. First, the radioactive nature of the waste
necessitates special plans and operations for on-site
measurements and sampling. Second, the radioactivity
in the samples may limit the number of laboratories that
can receive the samples or the types of analyses that can
be performed. The nature of such influences is not
always self-evident. Data users should be aware of the
potential effects on data quality resulting from the
complications of mixed waste characterization.
Field work demands that the on-site staff be able to
make decisions at the job site, a necessary prerequisite
if the sampling and measurement teams are to be capable
of reacting to unforeseen circumstances. It is also true
that in those circumstances, personnel tend to make
judgments based on their best, most applicable
experience. The experience of a worker who has
handled hazardous wastes will be biased toward the
chemical handling aspects, and decisions appropriate to
those types of wastes are to be expected. The opposite
may be true of workers experienced with handling
radioactive materials. It will be up to the data user to
critically review the field records to ensure that such on-
site decisions properly considered the data validity of
both sample components and that data were not
compromised.
The design of the sample collection program may
require compromises due to the differences in sample
handling and staff experience required for the principal
components of the waste. Mixed waste is only a small
fraction of all the low-level radioactive waste generated
in the country and an infinitesimal fraction of the total
hazardous waste. Therefore, staff with the appropriate
experience in both areas may not be available. The
requirements for special training and staff may conflict
with limitations in potential resources. Any given risk
assessment may be required to use staff that are very
experienced in one area (e.g., radiochemical sampling)
but may have only minimal training in the other mixed
waste component (e.g., sampling for organics). Data
recipients need to be especially alert to potential problems
caused by large discrepancies in the experience of staff
working such programs.
The external exposure rates or radioactivity
concentration of a specific sample may limit the time
that workers will be permitted to remain in intimate
contact with the samples. Possibly, collection personnel
12
-------
could take large samples and then split them into specific
analytical aliquots in a radioactively "cold" area. This
area may be "cold" with respect to radioactive
contamination butmay still be contaminated chemically.
This process increases both the chances of nonequi valent
samples being sentfordifferentanalyses and the potential
for cross-contamination between samples or from the
area chosen for sample splitting. Additionally, external
exposure rates from individual samples may require
that smaller samples be taken and special holding areas
be provided. Special handling requirements may conflict
with the size requirements for the analytical protocol,
normal sampling procedures, or equipment. For
example, sampling for hazardous waste constituents or
properties may require that samples be keptrefrigerated.
Samples containing radioactive materials may have to
be kept i n a restricted area to prevent personnel radiation
exposure or the spread of alpha and/or beta
contamination. The shielding requirements for
radioactive samples depend on their external exposure
rate, and confinement is based on the potential for
removable contamination. Such decisions will be made
by site health physics (HP) personnel who may be
unaware of temperature or holding time requirements.
In some cases, samples will have to be physically
surrendered to HP personnel for clearance prior to
removal from the site. Again, data recipients need to be
aleit for potential handling errors arising from these
types of situations.
Varying requirements for storage, preservation, and
special shipping complicate the logistics of mixed waste
programs. While most radiochemical procedures have
holding times and preservation methods in common
with metals analysis, they differ greatly with organic
analyses. Holding times for radioactively contaminated
samples are also affected by the half-life of the
radionuclide to be analyzed. After seven half-lives, less
than 1 % of the original activity would remain in the
sample. Separate samples should be taken for the
analyses requiring different handling and preservation.
Less obvious is the potential for biasing sampling
programs by selecting samples that can be safely handled
or legally shipped to the support laboratories. There
will be a human bias in the direction of handling
samples with the least shipping and storage
complications. This selection process can involve several
assumptions about the waste distribution which may or
may not be acknowledged. In an effort to ship the most
convenient samples, workers may assume that the
chemical contamination is not related to the radioactivity
levels in any way. The assumptions may also be made
that there are no qualitative differences in the
radioactivity content at different concentrations and
that the low activity samples can be quantitatively
analyzed and scaled to the higher activity areas by the
use of a simple ratio, of external exposure rates, for
example. Without documentary support, all of these
assumptions may be unwarranted, and sampling and
analysis schemes based on such assumptions may
compromise data integrity. The risk assessor must
ensure that such assumptions were not part of the
sample selection process by reviewing the appropriate
plans and records.
3.2.8 Fixed Laboratory Versus Field
Analysis
Fixed laboratory and field analyses are compared in Part
A, Section 3.2.9. A major factor to be considered in this
decision for radioactively contaminated sites is the type
of radiation present. Alpha-emitting radionuclides often
cannotbe measured in the field because of the attenuation
of the alpha particles by the sample matrix. Attenuation
can also cause problems for beta measurements under
certain conditions. Gamma-emitting radionuclides can
generally be measured in the field if the data can be
confirmed by fixed laboratory measurements.
w Field measurements must be made using
instruments sensitive to the type of
radioactivity present.
Selection of a radiometric method depends on the
number of radionuclides of interest and their activities
and types of radiations emitted, as well as on the level
of sensitivity required and the sample size available.
Exhibit 2 provides information on field survey
instruments for measuring gamma radiation, including
the advantages and disadvantages associated with each
type of instrument. Exhibit 3 provides similar
information for alpha and beta field survey instruments.
Measurements of external gamma radiation exposure
rates are used to delineate areas of contamination and
areas of observed contamination. Exposure rates are
usually measured with hand-held radiation survey meters
that utilize ion chambers, Geiger-Muller (G-M) tubes,
or gamma scintillation probes.
Surface gamma readings provide data only on radiation
levels at the surface, and they may miss contamination
from radionuclides at a greater depth that are shielded
by soil cover. In order to accurately characterize the
depth distribution of the radioactive contamination,
boreholes are augured or driven through key areas of the
site. Detectors, generally gamma scintillators, are
lowered into these boreholes, and readings of the gamma
exposure rate or gamma count-rate are obtained at
regular predetermined depths. Exhibit4 shows a typical
borehole apparatus. The risk assessor should consider
several issues pertaining to down-hole gammaprol'iling.
13
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EXHIBIT 2. FIELD SURVEY INSTRUMENTS FOR MEASURING GAMMA RADIATION
Specifications
Disadvantages
Moderate to high
range, approxi-
mately 0-2,000
mR/hour.
Reading is directly
proportional to
radiation field.
Poor sensitivity,
adequate for
near-background
radiation rates.
Accuracy ħ5% at
the high end of the
scale.
Suitable for use in
high radiation
fields.
Very portable.
Pressurized Ion
Chamber (PIC)
Range 1-500
uR/hour.
Suitable for
near-background
radiation rates.
Not as portable
Ion Chamber,
therefore, fewer
measurements per
day can be
recorded.
Accuracy ħ5% full
scale.
Reading is directly
proportional to
radiation field.
Moderate to high
range: 0-5,000
mR/hour.
Very portable.
Poor sensitivity,
adequate for
near-background
radiation rates.
Modern Geiger-
Muller (GM) Tube
Accuracy ħ10% full
scale.
Can also be used
for beta radiation
detection.
Reading is not
directly proportional
to radiation field
unless an energy
compensated tube
is used.
Suitable for
background
radiation rates
Reading is not
directly proportional
to radiation field;
response varies
with energy.
Gamma Scintillation
Detectors
Low range 0-5,000
u.R/hour.
Very portable.
Accuracy ħ10% at
high end to ħ30% at
low end of scale.
Suitable for
background
radiation rates
Response is
generally linear with
energy.
Organic Scintillators
Low range 0-25
uR/hour.
Accuracy ħ10% full
scale.
C21-002-77
14
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EXHIBIT 3. SURVEY INSTRUMENTS FOR MEASURING ALPHA AND BETA RADIATION
Detection
Alpha Scintillation
Probe*
Air Proportional
Detector
Geiger-Muller
(GM)
Pancake Type
Probe*
Side-Shielded
GM Probe*
Radiation Detected
alpha only
alpha only
alpha, beta and
gamma
beta and gamma
Advantages
High detection
efficiency.
Useful for many
screening
applications.
Very portable.
Large surface
area.
High detection
efficiency.
Large surface
area.
Can be used to
detect all types of
radiation.
Good for general
screening.
Discriminates
between gamma
and beta
radiation.
Good in high
gamma radiation
fields.
Disadvantages
Delicate window
may be easily
broken.
Measures only
alpha particles.
* Delicate window
may be easily
broken.
Measures only
alpha particles.
Can be affected
by mositure.
Sensitivity to all
types of radiation
decreases ability
to discriminate
between radiation
types.
Gamma reading
is not directly
proportional to
radiation field;
response varies
with energy.
* All probes are attached to the appropriate rate meter or sealer.
These include the calibration conditions for the detector,
the energy range the instrument is set to measure, and
variations in background caused by heterogeneous layers
of naturally occurring radioactivity.
C21-002-78
Alpha and beta radiations lack the penetrating ability
and range of gamma radiation, making their detection in
the field more difficult, but equally important, to
characterize. Preliminary radiation screening of samples
for alpha- or beta-emitting radionuclides must be
15
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EXHIBIT 4. ILLUSTRATION OF BORE-HOLE GAMMA PROFILING
Probe Support
Bore-hole Entrance
Contamination Layer
CZ1-002-80
performed using instruments sensitive to the type of
radiation being measured and must be performed much
closer to the contamination source. These results,
usually referred to as screening, can be used to identify
samples or areas containing radioactive contamination,
to establish that all samples leaving the site comply with
applicable U.S. Department of Transportation (DOT)
regulations, and to estimate the radioactivity content of
samples sent off site for analysis to ensure compliance
with the recipients radioactive materials license limits.
16
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Chapter 4
Steps in Planning for the Acquisition of Useable
Environmental Data
This chapter provides guidance to the RPM and the risk
assessor for designing an effective sampling plan and
selecting suitable analytical methods to collect
environmental data for use in baseline risk assessments.
Part A, Chapter 4 contains worksheets that can be used
to assist the risk assessor or RPM in designing an
effective sampling plan and selecting the proper
analytical methods.
4.1 STRATEGIES FOR DESIGNING
SAMPLING PLANS
The discussion in Part A, Section 4.1 regarding sample
location, size, type, and frequency applies to
radioactively contaminated sites as well. However, the
resolution and sensitivity of radioanalytical techniques
permit detection in the environment of most
radionuclides at levels that are well below those that are
considered potentially harmful, while analytical
techniques for nonradioactive chemicals are usually not
this sensitive. For radionuclides, continuous monitoring
of the site environment is important, in addition to the
sampling and monitoring programs described in Part A,
Section 4.1. Many field devices that measure external
gamma radiation, such as high pressure ionization
chambers, provide a real time continuous record of
radiation exposure levels. Such devices are useful for
determining the temporal variation of radiation levels at
a contaminated site and for comparing these results to
the variability observed at background locations.
Continuous measurements provide an added level of
resolution for quantifying and characterizing radiological
risk.
Additional factors that affect the frequency of sampling
for radionuclides include the half-lives and the decay
products of the radionuclides. Radionuclides with short
half-lives, such as 1-131 (half-life = 8.04 days), have to
be sampled more frequently because relatively high
levels of contamination can be missed between longer
sampling intervals. The decay products of the
radionuclides must also be considered, because their
presence can interfere with the detection of the parent
nuclides of interest, and because they also may be
important contributors to risks.
The Sampling Design Selection Worksheet shown in
Exhibit 5 may be used to assist in the design selection for
the most complex environmental situation, which is
usually soil sampling. This worksheet is similar to the
worksheet found in Part A, Exhibit 45. Directions for
filling out the worksheet can be found in Part A, Section
4.1.2. The worksheet should be completed for each
medium and exposure pathway at the site. Once
completed, this initial set of worksheets can be modified
to assess alternative sampling strategies.
There are two details to keep in mind while filling out
the worksheet:
Providing expedited sampling and analysis when
radionuclides with short half-lives are a concern.
Increasing reliance on field survey data in all
aspects of planning, since field data often provide
easy identification of many radionuclides and
guide sample collection.
Since field duplicates and blanks are such an important
determinant of measurement error precision, careful
attention must be paid to the number that are collected.
Part A, Exhibit 48 provides the number of duplicate
pairs of QC samples required to obtain a specific
confidence level.
4.1.1 Determining the Number of
Samples
An important aspect in designing a sampling plan is the
number of samples required to fully characterize each of
the three exposure pathways. Several methods for
Acronyms
CLP Contract Laboratory Program
DQO data quality objective
EMSL/LV Environmental Monitoring Systems
Laboratory/Las Vegas
NAREL National Air and Radiation Environmental |
Laboratory
NESHAPs National Emission Standards for
Hazardous Air Pollutants
NIST National Institute of Standards and
Technology
ORP/LVF Office of Radiation Programs/Las Vegas
Facility
PRP potentially responsible party
QA quality assurance
QAP Quality Assurance Program
QC quality control
RPM remedial project manager
SAP sampling and analysis plan
SDWA Safe Drinking Water Act
USNRC U.S. Nuclear Regulatory Commission
17
-------
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EXHIBITS. PARTI: MEDIUM SAMPLING SUMMARY
SAMPLING DESIGN SELECTION WORKSHEET
(Cont'd)
B. Base Map Code
A. Site Name
C. Medium: Groundwater, Soil, Sediment, Surface Water, Air
Other (Specify)
D. Comments:
E. Medium/
Pathway
Code
Exposure Pathway/
Exposure Area Name
Column Totals:
F. Number of Samples from Part II
Judgmental/
Purposive
Back-
ground
Statistical
Design
Geo-
metrical
or Geo-
statistical
Design
QC
G: Grand Total:
Row
Total
21 -002-093-01
19
-------
EXHIBITS. PART II: EXPOSURE PATHWAY SUMMARY
SAMPLING DESIGN SELECTION WORKSHEET
(Cont'd)
H.
Radionuclide of Potential Concern
and CAS Number
1.
Frequency
of
Occurrence
J. Estimation
Arithmetic
Mean
Maximum
K.
CV
L.
Background
M. Code (CAS Number) of Radionuclide of Potential Concern Selected as Proxy
N. Reason for Defining New Stratum or Domain (Circle one)
1. Heterogeneous Radionuclide Distribution
2. Geological Stratum Controls
3. Historical Information Indicates Difference
4. Field Screening Indicates Difference
5. Exposure Variations
6. Other (specify)
O. Stratum or Exposure Area
Name and Code
P.
Reason
Q. Number of Samples from Part III
Judgmental/
Purposive
R. Total (Part I, Step F):
Back-
ground
Statistical
Design
Geo-
metrical
or Geo-
statistical
Design
QC
Row
Total
20
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EXHIBITS. PART III: EXPOSURE AREA SUMMARY
SAMPLING DESIGN SELECTION WORKSHEET
(Cont'd)
O. Stratum or Exposure Area
E. Medium/Pathway Code
S. Judgmental or Purposive Sampling
Comments:
Domain Code _
Pathway Code.
Use prior site information to place samples, or determine location and extent of contamination. Judgmental or
purposive samples generally cannot be used to replace statistically located samples.
An exposure area and stratum MUST be sampled by at least TWO samples.
Number of Samples
Number of Background Samples
U. Statistical Samples
CV of proxy or radionuclidel of potential concern
Minimum Detectable Relative Difference (MDRD)
Confidence Level (>80%) Power of Test
Number of Samples
(See formula in Appendix IV)
T. Background Samples
Background samples must be taken for each medium relevant to each stratum/area. Zero background samples
are not acceptable. See the discussion on pp. 74-75 of Guidance for Data Useability in Risk Assessment Part A
(<40% if no other information exists)
(enter only if >75%
V. Geometrical Samples
Hot spot radius
. (Enter distance units)
Probability of hot spot prior to investigation
Probability that NO hot spot exists after investigation
(see formula in Appendix IV)
W. Geostatistical Samples
Required number of samples to complete grid +
Number of short range samples
X. Quality Control Samples
Number of Duplicates
Number of Blanks
Y. Sample Total for Stratum
(Part II, Step U)
(Minimum 1:20 environmental samples).
(Minimum 1 per medium per day or 1 per sampling
process, whichever is greater)
Judgmental/
Purposive
Back-
ground
Statis-
tical
Design
Geo-
metrical
or Geo-
statistical
QC
Row
Total
21
C21-002-93-3
-------
determining the required number of samples are
available, including the method discussed in Part A,
Chapter4andPart A, Appendix IV. Alternative methods
have been proposed by Schaeffer, et. al. (Schaeffer
1979) and Walpole and Meyers (Walpole 1978).
Each of the three exposure pathways from different
sample media present separate problems in designing a
sampling plan. A full discussion of sampling problems
is beyond the scope of this guidance. A brief discussion
of sampling soil, groundwater, and air pathways is
included as an example for a typical 10-acre site. The
number of samples and sampling locations listed are the
minimum number of samples required, and these
numbers will increase for most applications. The area
of consideration, the time available for monitoring, the
potential concentration levels of the contaminants, and
the funding available all influence the number of samples
to be analyzed.
Measurements of external exposure from soil are taken
with portable instruments as described in Section 3.2,
usually at 1 meter above ground level. The initial
measurements will be performed at predetermined grid
intersections, typically at intervals of 50 feet or 20
meters. This spacing produces about 20 to 25
measurements per acre. Larger spacing could be used
when surveying larger areas, especially if the
contamination is expected to be widespread and evenly
distributed at a constant depth below the surface.
Conversely, the distance between measurements would
decrease if the initial readings indicate contamination
that is localized or particularly elevated relative to
background. The primary objective in both cases is to
collect enough data to determine the locations of
maximum gamma radiation and to indicate zones of
equal intensity (i.e., isopleths) around these points.
This results in the familiar "bullseye" drawings indicating
areas of suspected maximum contamination. Gamma
exposure data are essential in selecting the locations for
soil sampling and borehole surveys. For a typical 10-
acre site, upwards of 250 radiation measurements will
be required. These data are normally superimposed on
a map or figure for ease of interpretation. The data
should indicate where background readings were
obtained for all sides of the site. Sources of radium
activity will decay to radon gas. The radon gas is more
mobile and can travel under the ground to give elevated
surface readings where there is no source of radioactivity.
When the radium source is removed the radon sources
disappear. In these situations borehole surveys and a
qualified health physicist or radiochemist can be used to
help interpret the data.
Borehole surveys involve the use of a gamma-sensitive
probe which is lowered into drilled or driven holes as
described previously. Measurements of gamma count
rate are made at predetermined depth intervals, typically
every 6 inches. A site investigation may produce 100 or
more borehole surveys. Depths of each hole will
normally extend at least 1 foot beyond the bottom of the
contaminated layer. When grade levels are
approximately equal, boreholes normally terminate at
the same depth. Therefore, boreholes showing no
evidence of contamination should have penetrated to at
least the same depth as those showing contamination.
Practically speaking, borehole depths vary across a site
as a function of the site characteristics and the sampling
equipment used.
Exhibit 6 illustrate s the need for borehole measurements.
Surface surveys cannot detect contamination occurring
at a great depth. Overlying soil cover which shields the
radioactivity may produce a greatly reduced response at
the surface. Depth profiles also provide a means for
selecting soil sampling locations and are useful in
prioritizing radiochemical analyses. This information
can also be used to correlate data for non-gamma-
emitting radionuclides to field surface radiation
measurements.
Both surface soil composites and core samples from a
subset of the locations selected by borehole profiling
should be collected. Subsurface soil cores should be
collected from 10 to 20% of the boreholes at a minimum
of approximately 12 locations. The distribution of soil
sample locations should be as follows:
Three from background locations.
Three from hot spot ("bullseye") locations
identified in the surface radiation survey.
Three from locations defining the limits of the hot
spots.
Three defining the fringes or boundaries of the
contaminated zone.
Soil cores are normally split into 6-inch increments.
These cores can also be combined and analyzed as a
composite, when resources are of critical importance.
Borehole samples are taken to provide information
concerning the extent of the contamination as well as
the depth of the contamination.
Compositing of borehole samples can result in
misinterpretation of the results when contamination
varies with depth across the area being investigated.
Groundwater samples should be taken from a minimum
of four locations: two background and two indicator
locations. If the sampling locations were chosen in the
absence of knowledge of the groundwater flow patterns,
22
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EXHIBIT 6. EFFECT OF SOURCE DEPTH ON SURFACE GAMMA
RADIATION MEASUREMENTS
25 microfl/hour
I^- 25 microR/hour
Greater Depth
of Fill
Lower Concentration of Activity
close inspection of comparative data is required to
ensure that background samples are not potentially
contaminated. Without knowledge of the groundwater
flow, background samples may be collected on opposite
sides of the site. If the groundwater flow is perpendicular
to the line between these two locations, both are likely
to be true backgrounds. If the flow is parallel to this line,
one or the other may be contaminated. Contamination
of both "background" samples may suggest local flow
reversal or contamination from sources other than the
site under investigation. A thorough data evaluation
should indicate the true nature of the situation.
Air samples should be collected from a minimum of six
locations. At least two of these should be background
locations. To achieve the required sensitivity for
environmental analyses, approximately 300 m3 will be
required. Occasionally, a specific isotope may require
special collection efforts. For example, tritium will
normally not be collected on filters but on silica gel or
other absorbers, and sampling for gases usually requires
special equipment and techniques. These special
circumstances should be described in the sampling and
analysis plan (SAP). The choice of filter material is also
important; it is determined by flow rate, the size of the
particulate matter being sampled, and the expected
loading of the filter during the sampling time. In
general, membrane filters are used for low flow rates to
detect small amounts of submicron particles, while
paper or glass fiber filters are used for larger flow rates
and larger particles. Some filter materials contain large
amounts of naturally occurring radioactivity (i.e., K-40
in glass fiber filters) and will not be applicable in certain
situations.
A maximum of 10 to 12 samples per site can be expected
from other sources as indicators of an ingestion pathway.
23
-------
These may be surface water, sediment, benthic
organisms, fish or other indicators. A minimum of two
background samples per media should also be collected.
4.2 STRATEGY FOR SELECTING
ANALYTICAL METHODS
Currently, there is no single, universally accepted
compilation of radiochemical procedures. However,
there is a preferred priority of procedures (although
developed or approved for other applications) that can
be applied to risk assessments.
In general, where the Agency has mandated or
recommended radiochemical analytical procedures for
compliance with other programs, (hose procedures
should be considered for the same or analogous media
when analyzing samples for risk assessments. A key
factor in method selection is the constraints that were
established during the data quality objective (DQO)
process. Exhibit 7 summarizes a preferred order of
method selection.
Media-specific procedures are as follows:
Water. Procedures mandated for compliance with the
Safe Drinking Water Act (SOWA) should be used for
analysis of both surface and groundwater samples for
analy tes specified in the SOW A. Procedures for analytes
not specifically mentioned in the SDWA may be selected
from the other compendia listed in Exhibit 8.
Air samples. The National Emission Standards for
Hazardous Air Pollutants (NESHAPs): Radionuclides
(40 CFR 61 Appendix B) includes methods for the
analysis of radioactivity in air samples. This appendix
presents both citations of procedures for specific isotopes
and general "principles of measurement." The general
principles are similar to the counting methods discussed
previously. Where the analyte/media combinations
match those pathways under investigation at a site, the
applicable individual method should be used. When a
specific isotope is not mentioned, methods utilizing the
appropriate principles of measurement in concert with
appropriate QA/QC procedures will be acceptable.
Soil, sediment, vegetation, and benthos. A number of
procedures exist that contain methods for the analysis of
soil, sediment, and biological media for a variety of
radionuclides. Compendia for these procedures are
listed in Exhibit 8 and provide ample resources for the
selection of analytical methods.
In general, whether the procedures are selected from the
SDWA, NESHAPs, or one of the other suggested
compilations, the procedures are subject to many
limitations. Some procedures assume the presence of
only the isotope of interest; some assume the absence of
a specific interfering isotope. Procedures involving
dissolution or leaching may assume that the element of
interest is in a specific chemical form. Careful attention
to the conditions and limitations is essential both in the
selection of radiochemical procedures and in the
interpretation of data obtained from those procedures.
If the user is unsure of the applicability of a method to
a candidate site or specific situation, assistance can be
obtained from the Regional Radiation Representative,
Office of Radiation Programs, or radiochemistry staff at
the National Air and Radiation Environmental
Laboratory in Montgomery, Alabama (NAREL), the
Office of Radiation Programs/Las Vegas Facility (ORP/
LVF), or the Office of Research and Development-
Environmental Monitoring Systems Laboratory in Las
Vegas, Nevada (EMSL/LV).
EXHIBIT 7. ORDER OF PRIORITY FOR SELECTION OF ANALYTICAL METHODS
Methods Required by EPA Regulations (e.g., NESHAPs or NPDWR)
Methods Published by EPA Laboratories (e.g., NAREL, Montgomery, AL or EMSL, Las Vegas,
NV)
National Consensus Standards (e.g., ASTM, APHA, IEEE)
Methods Published by Other Federal Agencies (e.g., DOE, USGS)
Methods Published in Refereed Technical Literature
Methods Published by Other Countries or International Organizations (e.g., IAEA, NRPB)
C21-002-87
24
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EXHIBIT 8. REFERENCES FOR RADIOCHEMICAL PROCEDURES
American Public Health Association, "Methods of Air Sampling", 2nd Edition, APHA, New York,
NY (1977).
American Society for Testing Materials, "1987 Annual Book of ASTM Standards", ASTM,
Philadelphia, PA.
APHA/AWNA/WPCF, "Standard Methods for the Examination of Water and Wastewater", 17th
Ed., APHA, Washington, DC.
Department of Energy, "RESL Analytical Chemistry Branch Procedures Manual", IDO-12096,
VSDOE, Idaho Falls, ID.
Department of Energy, "EML Procedures Manual", 26th Edition, Report EML-300, USDOE,
New York, NY.
Environmental Protection Agency, "Radiochemical Analytical Procedures for Analysis of
Environmental Samples", EMSL-LV-0539-17, USEPA Environmental Monitoring and Support
Laboratory, Las Vegas, NV.
Environmental Protection Agency, "Radiochemistry Procedures Manual", EPA 52015 84-006,
EEERF, Montgomery, AL.
Environmental Protection Agency, "Indoor Radon and Radon Decay Product Measurement
Protocols", EPA 520/1-89-009, USEPA, Washington, DC.
4.2.1 Selecting Analytical
Laboratories
* The shipper of radioactive material is
responsible for ensuring that the recipient
is authorized to receive the shipped material
and for compliance with all applicable
shipping and labelling regulations.
The risk assessorneeds to be aware of limitations placed
on the samples by regulatory or licensing considerations
due to the sample's radioactivity content. Adherence to
existing regulations is an obvious requirement.
Radioactively contaminated sites are likely to generate
samples that may be receivable only by laboratories
having an appropriate license to handle radioactive
materials. Such licenses may be issued by state agencies
or the U.S. Nuclear Regulatory Commission (USNRC).
In either case, the shipper is responsible for ensuring
that the recipient is authorized to receive the shipped
material and is responsible for complying with all
applicable shipping and labeling regulations (DOT,
etc.). Two prerequisites must be filled to permit the
shipper to fulfill this obligation:
A copy of the recipient laboratory' s current valid
radioactive materials license must be obtained
prior to shipment of any samples and be available
C21-002-88
to the shipper at the location of sample packaging
and shipment.
The shippermusthave adequate field measurement
equipment available at the site to ensure that
samples are within license limits.
Laboratories may have license limits which are specified
either on aper sample basis or for the facility as a whole.
When facility limits are imposed, the laboratory should
be requested to provide its administrative limits on
individual samples or sample batch lots. While these
requirements do not directly affect the data, compliance
with these requirements can be complicated and time-
consuming and may interfere with holding times or
other analytical requirements. The risk assessor should
review the procedures used to comply with these
requirements to ensure that such compliance will not
affect data integrity.
Many radiochemistry laboratories may not be prepared
to associate individual sample data with specific
analytical batches. Efficiency calibrations, backgrounds,
analytical blanks, instrument performance checks, and
other QC parameters all can have varying frequencies
and therefore apply to different time periods and different
analytical batches. The traditionally applied data
qualifiers may not have direct analogues in
25
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radiochemistry or may require alternate interpretation.
When receiving data from a mixed waste laboratory
which has historically developed from a radiochemistry
laboratory, the risk assessor will be required to evaluate
different relationships between QC and samples that are
typical for non-radiochemical data.
The conventions for the use of data qualifiers are closely
tied to data reporting requirements. QA/QC programs
for radiochemical laboratories have developed separately
with a different emphasis. The emphasis for chemical
analysis has been to coordinate the QC data with batches
of analyses within fairly narrow time periods.
Radiochemical measurement methods emphasize QC
data collection based on measurement systems, due to
the stability of properly maintained systems and the
count-time intensive nature of the analyses. It is not
unusual for single measurements to monopolize a given
instrument for several hours. It is, therefore, impractical
to rerun standard curves at frequent intervals, since
other methods of establishing instrument and method
performance have been devised.
The probability that non-Contract Laboratory Program
(CLP) data or potentially responsible party (PRP) data
may have to be used for evaluation will be greater for
sites that have more seriousmixed waste considerations.
Consideration of non-CLP data useage is discussed in
Chapter 5. In addition, not all methods may be available
for every sample. Availability of a specific method
depends on contamination levels and types and levels of
containment available at the laboratory. Not all
equipment may be available for every level of
containment and shielding. It is possible that different
equipment or methods may be used for the same
parameter in samples with different levels of radioactive
contamination. Personnel protection restrictions may
limit exposure rates from individual or batch analytical
aliquots. Resulting limitations on sample size may be
reflected in limitations on the achievable detection
limits.
Laboratories performing radiochemical analyses should
have an active and fully documented Quality Assurance
Program (QAP) in place. There are several documents
that provide guidance for the preparation of a QAP.
Some of these documents include Test Methods for
Evaluating Solid Wastes (SW846) (EPA 1986), United
States Nuclear Regulatory Commission Regulatory
Guide 4.15 (NRC 1977), United States Department of
Energy Environmental Survey Manual (DOE 1988),
andANSI/ASMENQA-1 (ASME1989). The procurer
of radioanalytical services should specify the type of
QAP that is required and should be prepared to evaluate
programs in such formats. The following are the criteria
that are common to these documents and should be
considered as the minimum requirements of an adequate
QAP:
Quality Assurance Program. The QAP must be
written and must state the QA policy and objectives for
the laboratory. The primary function of QA/QC is the
definition of procedures for the evaluation and
documentation of the sampling and analytical
methodologies and the reduction and reporting of data.
The objective of QA/QC is to provide a uniform basis
for sample handling, sample analysis, instrument and
methods maintenance, performance evaluation, and
analytical data gathering.
Organizational structure. The laboratory should
maintain an organizational document defining the lines
of authority and communication for reporting
relationships. This document should include job
descriptions of management and staff, including a QA
officer.
Qualifications of personnel. Qualifications of
personnel performing quality related tasks should be
specified and documented, including resumes, education
level, previous training, and satisfactory completion of
proficiency testing.
Operating procedures and instructions. Written
instructions and/or procedures covering the
administrative, operations, and quality levels of the
laboratory should be established and include, but are not
limited to:
Sample collection.
Sample receipt and shipping.
Analytical methods.
Radioactive material handling.
Radioactive waste disposal.
Data verification.
Software quality assurance.
Sample preparation and storage.
Procurement.
Quality assessment.
Chain-of-custody.
Review of procedures.
Data evaluation.
Reporting of data.
Records.
26
-------
Audits.
Implementation of inter- and intralaboratory QC
program.
Calibration and operation of laboratory
instruments.
Performance checks andmaintenance of laboratory
instruments.
Preparation and standardization of carrier and
tracer solutions.
The following are criteria that should be considered as
additional requirements for an environmental sampling
program:
Design control. The laboratory should maintain a
document defining the flow path of samples through the
laboratory, including sample receipt, sample log-in,
sample analysis and measurement, data validation and
processing, reporting, and records management.
Inter- and intralaboratory analyses. Reagent blanks,
matrix blanks, field (equipment) blanks, field duplicates
(splits), laboratory duplicates, blind and double blind
matrix spikes, and verification (reference) standards
should constitute at least 10% of the samples analyzed.
The actual numbers of each type of analysis should be
specified in the SAP.
Appropriate QC testing should be included in the work
plan for projects other thaii the established, routine
services supplied by the analytical laboratory.
The laboratory should assure that measuring and testing
devices used in activities affecting quality are of the
proper range, type, and accuracy to verify conformance
to established requirements. To assure accuracy,
measuring and test equipment should be controlled,
calibrated, adjusted, and maintained at prescribed
intervals as specified by procedures. Calibrations should
be performed using standards or systems that are
traceable to the National Institute of Standards and
Technology (NIST). If no national standards exist, the
basis for calibration should be documented. The method
and interval of calibration for each item should be
defined. The specifications should be based on the type
of equipment, stability characteristics, required accuracy,
and other conditions affecting measurement control.
Additional routine checks of baseline or background
characteristics and performance checks should be made
on frequencies appropriate for each instrument with
such frequencies established in approved procedures.
Each of the above situations places a greater burden on
the risk assessor to perform a careful review. Professional
judgment is required to assess the final effect of varying
methods, equipment, aliquot sizes, andQA/QC activities
on the analytical results.
27
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Chapter 5
Assessment of Environmental Data for Useability in
Baseline Risk Assessments
This chapter provides guidance for the assessment and
interpretation of environmental radioanalytical data for
use in baseline human health risk assessments. Data
assessment is accomplished by examining two general
sets of data. One set of data consists of the data
supporting the individual analysis. Questions often
asked of these data include:
Were all the correct parameters used?
Were the specified methods used?
Were all controlled parameters maintained within
specified limits?
Were the calculations performed correctly?
Do the final analytical results make sense in light
of the site history and results obtained for other
samples?
Are the analytical results legally defensible if
enforcement activity or cost recovery activity is to
be pursued by EPA?
The second set of data supports the validity of the
method and proper operation and calibration of
measurement equipment. This set of data comprises
instrument calibration, operational checks, method
demonstration and cross-check programs, and routine
QC samples. Both sets of data need to be examined to
judge the validity of individual analyses.
To evaluate radioanalytical data, it is necessary to
understand the normal methods of calculating
radiochemical values for activity concentration, error,
minimum detectable concentration (MDC), and lower
limit of detection (LLD). Generalized equations for
these calculations are given in Exhibits 9 and 10. These
equations contain the parameters used to calculate the
radioactivity in a given sample. Although not .all
parameters will be used in every radioanalysis, these
equations will serve as the basis for the following
discussion of individual parameters. This discussion
assumes the user has specified, received, or can obtain
access to the data shown in Exhibit 11.
Activity, error, and detection limits are the parameters
generally reported by radioanalytical laboratories.
Activity, which is the estimate of radioactivity in a
sample, may be a screening parameter (e.g., gross
alpha) or isotope specific (e.g., Sr-90). Activity must
always be calculated from a net count-rate because all
radioactivity measurement systems are subject to
background count-rates from cosmic radiation, the
laboratory environment, and their own construction
materials, among other sources.
Error terms are usually reported based on counting
statistics only. While Equation 2 in Exhibit 9 calculates
a single standard deviation, it is common practice to
report radiochemical data to two standard deviations.
To determine whether two analytical results are
significantly different, it is important to know the number
of standard deviations to which the reported errors
correspond.
A standard radiochemical data report should include
values for the activity concentration and the associated
error, or the MDC. The data user must ensure that the
MDC value is in fact sample specific, and not a
generalized value. Some laboratories report the activity
concentration andassociated error only when the sample
is above the sample-specific MDC. Others will report
the activity concentration and associated error even
when the results are less than zero (negative). The
reporting conventions should be decided prospectively
and the requirements communicated to the analytical
laboratory.
The risk assessor must evaluate the radioanalytical data
for completeness and appropriateness and to determine
if any changes were made to the work plan or the
sampling and analysis plan (SAP) during the course of
the work. The risk assessor will assess the radioanalytical
data for completeness, comparability, represen-
tativeness, precision, and accuracy as described in Part
A, Chapter 5.
Acronyms
EPA U.S. Environmental Protection Agency
LLD lower limit of detection
MDC minimum detectable concentration
QC quality control
SAP sampling and analysis plan
29
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EXHIBIT 9. GENERALIZED EQUATIONS FOR RADIOACTIVITY CALCULATIONS
ACT =
SC-BC
ST BT
2.22x106 x EFF x CY x All x RY x DIFs
(1)
ERR =
SC _BC
ST2 BT2
2.22x106 x EFF x CY x ALI x RY x DIFs
(2)
MDC =
4.65 x
BC
BTxST
2.22x106 x EFF x CY x ALI x RY x DIFs
(3)
LLD =
4.65 x
BC
BTxST
2.22x106x EFF x RY
(4)
Where:
RY
DIFs
Activity in units of microCuries per units of ALI
One standard deviation counting error (Same units as ACT)
Minimum detectable concentration (Same units as ACT)
Lower limit of detection in units of microCuries at time of counting
Total sample counts
Elapsed time for which sample was counted (minutes)
Total background counts
Elapsed time for which background was counted (minutes)
Number of disintegrations per minute (dpm) per microCurie
Counting efficiency for radiation being measured (counts per minute
detected for each disintegration per minute actually occurring in sample)
Aliquot of sample actually analyzed (units of volume or mass)
Yield of the radiochemical separation procedure (fractional unit of
recovery)
Radiation yield (number of radiations of the type being measured which
are produced per each disintegration which occurs. For gamma spec-
trometry this is commonly called gamma abundance.)
Product of various decay and ingrowth factors. The most commonly
used DIFs are shown in Exhibit 10.
C21-002-89
30
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EXHIBIT 10. GENERALIZED EQUATIONS FOR RADIOACTIVITY
DECAY AND INGROWTH CORRECTION FACTORS
DFA= 6
0.693
HLA
xT,
(5)
DFC =
0.693
HLA
xT,
1 - 6
0.693
HLA
(6)
IDF= 1 - e
0.693
HLD
(7)
DFD= e
0.693
HLD
xT.
(8)
Where:
DFA
Decay correction to obtain activity at the end of the sampling period
(continuous collection) or at the time of collection (grab sample)
Corrects average count rate during acquisition to count rate at beginning
of counting
Calculates fraction of the decay product ingrowth for radiochemical
methods where the decay product is the entity actually counted
Corrects for decay of the decay product between the end of ingrowth and
beginning of counting
Half-life for isotope of interest
Half-life of the decay product (if the decay product is isotope counted)
Time interval between end of sampling and beginning of counting
Elapsed time for acquisition of sampling counts
Time permitted for ingrowth of the decay product activity
Time interval between last separation of parent and the decay product
isotopes and the beginning of counting of the decay product.
CZ1-002-90
31
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EXHIBIT 11. DATA REPORT REQUIREMENTS FOR
TYPICAL RADIOCHEMICAL ANALYSIS
The following are the minimum parameters required on a radiochemical analytical report
to recreate and verify the analytical report.
Lab Sample ID
Field Sample ID
Start Collection Time/Date
Stop Collection Time/Date
Flow Rate
Volume/Weight Adjustment Factors
Aliquot Analyzed (Vol/Wgt)
Chemical Yields
Start and Stop Times and Dates for the Sample Count
Total Sample Acquisition Time
Start and Stop Times and Dates for the Background Count
Total Background Acquisition Time
Energy Regions of Interest
Uncorrected Gross Sample Counts
Gross Background Counts
Gamma Abundance Values
Counter Efficiency
Sample Specific Correction Factors
Start and Stop Times & Dates for Decay Product Ingrowth
Start and Stop Times & Dates for Radioactive Decay
C21-002-91
32
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Chapter 6
Application of Data to Risk Assessment
This chapter discusses the application of radioanalytical
data for risk assessment. Guidance is provided for
reviewing data for consistency and completeness and
for evaluating observed contamination, source term
quantity, and contamination levels. Because similarities
exist between the evaluation and application of analytical
data for radioactive and nonradioactive risk assessment,
the reader is encouraged to review the discussions
provided in Part A, Chapter 6.
Before radioanalytical data can be used for risk
assessment, the user must determine the acceptability
and usefulness of the data sets derived from the field and
laboratory analyses. The data user should then review
the entire data package for consistency and completeness
among the data sets. At a minimum, this review should
focus on the following areas:
Radionuclides of concern.
Discrimination of site contamination from
background.
Exposure pathways.
Documentation of analytical procedures and
results.
6.1 RADIONUCLIDES OF CONCERN
The data user should review the list of radionuclides of
concern for each migration pathway for completeness
with respect to the criteria listed in Section 3.2:
Atomic number and atomic weight.
Radioactive half-life.
Principal decay modes, radiation decay modes,
energies, and abundances.
Chemical and physical form.
Decay products.
6.2 DISCRIMINATION OF SITE CON-
TAMINATION FROM BACK-
GROUND
Radionuclide specific activity concentrations (and
radiation exposure rates, where applicable) for
background samples are required for each pathway.
These data are used to characterize thenaturally occurring
levels of radionuclides in all pertinent media and to
facilitate discrimination of site contamination from
background. These data need to be of sufficient quality
for risk assessment purposes. Data quality depends on
whether background levels were determined by site-
specific analysis or were derived from the literature. In
general, site-specific background data are recommended
over values obtained from the literature because site-
specific measurements can account for the local
background variability, and the quality of site-specific
analytical data can be directly assessed through the use
of QA/QC samples.
Care must be taken to ensure that the appropriate
background sample is taken for each analytical sample,
and that the background sample is the equivalent of the
analytical sample. It must originate in the same
conditions of an uncontaminated area, e.g., the same
soil classification as a borehole sample taken on site, but
from an environmentally uncontaminated area.
When published data are used to establish background
concentrations, the data must be determined to be
representative of the site. The concentration utilized to
represent the background should be in the 95% upper
confidence limit of the range of literature data.
Ideally, both site-specific data and that from the literature
should be available and utilized to draw comparisons
between and conclusions about the quality of background
concentration data. Reported background values for a
specific radionuclide in a given medium that fall outside
(i.e., either below or above) the concentration range
expected from values in the literature, should alert the
data user to the need to review the appropriateness or
representativeness of thebackground sampling location
or the performance and sensitivity of sampling and
analysis techniques, radiochemical procedures, or
measurement techniques.
6.3 EXPOSURE PATHWAYS
The risk assessor should review the data package to
ensure that all relevant exposure pathways have been
sampled and that radioanalytical data are provided for
these pathways. For example, evaluation of the soil
exposure pathway should include measurements of
activity concentrations of radionuclides in soil, as well
as external radiation exposure measurements from all
Acronyms
QA quality assurance
QC quality control
SAP sampling and analysis plan
SOP standard operating procedure
33
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contaminated areas. The locations of all background
and site sampling points should be clearly defined and
marked on the site map.
6.4 DOCUMENTATION OF ANA-
LYTICAL PROCEDURES AND
RESULTS
All radioanalytical procedures used to determine site
data should be documented. These procedures and
resulting data sets should be reviewed to determine
whether the proper procedures were used for the types,
abundances, and energies of the radiations emitted by
each radionuclide and should ensure that the data are
presented in the appropriate activity concentration units
(e.g., pCi/g dry weight or pCi/g wet weight for soil, pCi/
L for water, pCi/g fresh weight or pCi/g dry weight or
pCi/g ash weight for vegetation, or pCi/m3 for air),
along with their associated error. The required activity
concentration units should be specified in the sampling
and analysis plan (SAP).
To document radiochemical results properly, a detailed
compilation of supporting documentation is required.
Records of all types should be continuous. Data
originally recorded in a notebook may be transferred to
a form, entered into a computer, and finally printed as
either input parameters or as intermediate, calculated
data. In these cases, copies of all supporting logbooks
and forms are required, not just the final printed copy.
To support the reported analytical data, a broad range of
documentation should be required of the analytical
laboratories. The materials required for QA support
documentation are shown in Exhibit 12.
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EXHIBIT 12. RADIOCHEMICAL QUALITY ASSURANCE
SUPPORT DOCUMENTATION
Sample Collection Data:
Field survey data
Sample collection field logs
Field preparation data sheets
Shipping/transmittal forms
Chain-of-Custody forms
Sample receipt logs
Sample login forms/logs
Laboratory analysis request and distribution forms
Calibration data for sample collection equipment
Radiation screening information
Copy of NRC/State RAM license of party receiving samples
Analytical Data:
Preparation/Chemistry Data
Sizes of aliquots processed
Concentration/dilution factors
Chemical yield data
Evidence of preparation of
counting aliquots
Dates and times of processing and
separations
Analogous data for applicable QC
samples
Initials of the analyst(s)
Copy of SOPs used for
preparation
Counting Data
Sample sizes and counting geometries
Sample counts
Background counts
Reagent blank counts
Acquisition times, sample & background
Date and times of all counting
Counter efficiencies
Identification of analysts
Identification of counters used
Counter printouts, including but not limited to peak
search and quantitation printouts for spectral methods |
Counter crossover and interference data (GPC)
Analogous data for appropriate QC samples
Calculated results, propagated errors, detection limits
C21-002-92
35
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EXHIBIT 12. RADIOCHEMICAL QUALITY ASSURANCE
SUPPORT DOCUMENTATION
(Cont'd)
Instrument Data:
Performance Data
Instrument backgrounds
Efficiency checks
Check source documentation
Energy calibration/resolution checks
(spectrometry)
Plateau checks (gas proportional
counters)
Logs and control charts of these data
Acceptance criteria
Corrective actions taken and the bases for
same
Instrument Calibrations
Standards preparation and traceability
Calculation of efficiencies
Supporting counting data
Quench correction curves (LSC)
Acceptance criteria
Efficiency vs Energy curves (HRGS or Nal)
Transmission Factor curves (GPC)
Energy vs. Channel plots (spectrometry)
Corrective actions taken and bases for same
Quality Control Data:
Results and supporting raw data for scheduled blanks, replicates and refererence samples
Results and supporting raw data for blind blanks, replicates and refererence samples
Results and supporting raw data for participation in interlaboratory programs
Control charts of above data
Acceptance criteria
Corrective actions taken and bases for same
The following procedures and supporting information may be submitted once, either at the project
inception or prior to contract award:
Official or controlled copies of all procedures used to acquire, preserve and ship samples;
perform the above analyses; and calculate results
Calculation and reporting conventions
Algorithms used to calculate the submitted data
Verification of software program results
Qualifications for all analysts
C21-002-92-1
36
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Appendices
I. GLOSSARY OF RADIATION CONCEPTS, TERMINOLOGY AND UNITS 39
II. RADIOACTIVE SUBSTANCES IN THE ENVIRONMENT 45
III. EPA RADIATION PROGRAM STAFF 65
37
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APPENDIX I
Glossary of Radiation Concepts, Terminology and Units
Absorbed dose (D) is the mean energy imparted by ionizing radiation per unit mass of material (e.g., biological
tissue). The SI unit of absorbed dose is the joule per kilogram, also assigned the special name the gray (1 Gy
= 1 joule/kg). The conventional unit of absorbed dose is the rad (1 rad = 100 ergs per gram = 0.01 Gy).
Activity refers to the average number of nuclear disintegrations of a radioisotope that occur per unit time. It
is the product of the number of atoms and the radioactive decay constant, X, of a given radioisotope, and can
be defined as follows:
where A is the activity of the radioisotope in units of disintegrations per second (dps) or disintegrations per
minute (dpm), N is the number of atoms present at a specified time, and X is the decay constant in reciprocal
units of time (i.e., sec"1 or min"1), defined as:
Tl/2 Tlf2
where Tia is the radioactive half-life of the radioisotope. Further, the activity of a radioisotope alone (i.e.,
unsupported by the decay of another radioisotope) can be calculated at any point in time t based on the activity
present at some initial time t = 0 and on its decay constant, as follows:
A(t) = A0e-"
where A(t) is the activity of the radioisotope at time t and A,, is the initial activity of the isotope at t = 0.
Quantities of radioactive isotopes are typically expressed in terms of activity at a given time t (see the definitions
for Becquerel, Curie, counts per minute, and disintegrations per minute).
Atomic number is the number of protons in the nucleus of an atom. In its stable and neutral state, an atom has
the same number of electrons as it has protons. The number of the protons determines the atom' s chemical
properties. For example, an atom with one proton is a hydrogen atom, and an atom with 92 protons is a
uranium atom. The number of neutrons of an atom may vary in number without changing its chemical
properties, only its atomic weight.
Atomic weight is the total number of neutrons and protons in the nucleus of an atom.
Becquerel (Bq) is the SI unit of activity defined as the quantity of a given radioisotope in which one atom is
transformed per second (i.e., one decay per second or 1 dps). One Bq is equal to 2.7E-11 Ci.
Committed dose equivalent CHT cn) is the integral of the dose equivalent in a particular tissue for 50 years after
intake (corresponding to a working lifetime) of a given radionuclide.
Cosmogenic radionuclides are those radionuclides (e.g., H-3 and C-14) continually produced by natural cosmic
processes in the atmosphere and not by the decay of naturally occurring series radionuclides.
39
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Counting efficiency is the ratio of the number of counts registered by a given radiation-detection instrument each
minute (i.e., cpm) over the number of nuclear disintegrations per minute of the radioactive source (dpm) being
measured. For example, given a source decaying at a rate of 1,600 dpm and an instrument that detects 400 cpm,
then the counting efficiency of this detection system would be 0.25 (400/1,600 = 1/4) or 25%.
Counts per minute (cpm) is the unit that describes the number of disintegrations detected by a radiation-
detection instrument. Because radiation is emitted isotropically (i.e., equally in all directions) from a radioactive
source, the probes of most radiation-detection instruments cannot detect all radiation emitted from a source.
Therefore, cpm and dpm will not be equal. However, if the response characteristics of a detector are known
for a given radiation source, the relation between cpm and dpm can be determined (see Counting efficiency).
Curie (Ci) is the conventional unit of activity defined as the quantity of a given radioisotope that undergoes
nuclear transformation or decay at a rate of 3.7 x 10'° (37 billion) disintegrations each second. One Ci is equal
to 3.7 x 10'° Bq and approximately equal to the decay rate of one gram of Ra-226. Because the curie is a very
large amount of activity, subunits of the curie are often used:
1 millicurie (mCi) = 10'3 Ci
1 microcurie (/jCi) = 10'6 Ci
1 nanocurie (nci) = 10"9 Ci
1 picocurie (pCi) = 10'12 Ci
1 femtocurie (fci) = 10'13 Ci
Disintegrations per minute (dpm) is the unit that describes the average number of radioactive atoms
in a source disintegrating each minute. A 500 dpm source, for example, will have 500 atoms disintegrating every
minute on the average. One picocurie (pCi) equals approximately 2.22 dpm.
Dose equivalent (H) considers the unequal biological effects produced from equal absorbed doses of different
types of radiation and is defined as:
H = DQN
where D is the absorbed dose, Q is the quality factor that considers different biological effects, and N is the
product of any modifying factors. Quality factors currently assigned by the International Commission on
Radiological Protection (ICRP) include Q values of 20 for alpha particles, 10 for protons, and 1 for beta
particles, gamma photons, and x-rays. Q values for neutrons depend on their energies and may range from 2
for thermal neutrons to 11 for 1 MeV neutrons. These factors may be interpreted as follows: On the average,
an alpha particle will inflict approximately 20 times more damage to biological tissue than a beta particle or
gamma ray, and twice as much damage as a neutron. The modifying factor is currently assigned a value of unity
(N=1) for all types of radiation. The SI unit of the dose equivalent is the sievert (Sv), and the conventional unit
is the rem (1 rem = 0.01 Sv). A commonly used subunit of the rem is the millirem (mrem).
Electron Volt (eV) is the unit used to describe the energy content of radiation, defined as the energy acquired
by any charged particle carrying a unit (electronic) charge when it falls through a potential of 1 volt; it is
equivalent to 1.6 x 10"'2 ergs. Alpha particles range in energy from 1 to 10 million electron volts (MeV), and
beta particles are emitted over a wide energy range from a few thousand electron volts (keV) to a few MeV.
Gamma photons also typically range from a few keV to one to two MeV.
Effective dose equivalent (HE) and the committed effective dose equivalent (HE^0), defined as the weighted sums
of the organ-specific dose equivalents, were developed by the ICRP to account for different cancer induction
rates and to normalize radiation doses and effects on a whole body basis for regulation of occupational exposure.
In general, the reader need not be concerned with these concepts for HRS scoring purposes. Still, the interested
reader is referred to ICRP publications (ICRP 1977 and ICRP 1979) for additional information on these topics.
40
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Exposure (sometimes called the exposure dose) refers to the number of ionizations occurring in a unit mass of
air due to the transfer of energy from a gamma or x radiation field. The unit of exposure is the roentgen (R)
expressed as coulombs of charge per kilogram of air (1 R = 2.58 x W4 C/kg). A common simplification is that
1 R of gamma or x-radiation is approximately equal to 1 rad of absorbed dose and to 1 rem of dose equivalent.
Exposure rate (or exposure dose rate) refers to the amount of gamma or x-ray radiation, in roentgen, transferred
to air per unit time (e.g., R/hr or R/yr). Commonly used subunits of the roentgen are the milliroentgen (1 mR
= 10"3 R) and the microroentgen (jjR = 10"6 R), with corresponding subunits of mR/hr or /jR/hr for exposure
rates. The roentgen may be used to measure gamma or x radiation only.
External exposure refers to radiation exposure from radioactive sources located outside of the body.
Gray (Gy) is the SI unit of absorbed dose (1 Gy = 1 Joule kg' = 100 rad).
Internal exposure refers to radiation exposure from radionuclides distributed within the body.
ICRP is the International Commission on Radiological Protection.
lonization of an atom is the removal of one of its orbital electrons. When an electron is removed, two charged
particles, or ions, result: the free electron, which is electrically negative, and the rest of the atom, which bears
a net positive charge. These are called an ion pair. Radiation is one mechanism that produces ionization.
Alpha and beta radiation cause ionization primarily through collisions, that is, moving alpha and beta particles
physically "collide" with orbital electrons, transferring some or all their energy to these electrons. Multiple
collisions with electrons eventually reduce the energy of the alpha or beta particle to zero. These particles are
then either absorbed or stopped. De-energized beta particles become free electrons that often are absorbed by
positive ions. A doubly-positive alpha particle frequently captures two free electrons to become a helium atom.
Gamma radiation causes ionization by three processes: the photoelectric effect, the Compton effect, and pair
production. The photoelectric effect occurs when the total energy of the gamma photon is absorbed by an
electron and the incident gamma photon is annihilated. The Compton effect occurs when part of the energy of
the gamma photon is transferred to an orbital electron and the initial incident gamma photon is deflected with
reduced energy. In pair production, the incident gamma photon interacts with the atomic nucleus forming two
electrons and the photon is annihilated. Because of their ability to remove orbital electrons from neutral atoms,
alpha, beta, and gamma radiation are referred to as ionizing radiation.
Isotopes are atoms of the same chemical element that have the same number of protons but different numbers
of neutrons. All isotopes of a given element have the same atomic number but different atomic weights.
Naturally occurring radionuclides are those radionuclides of primordial origin and terrestrial nature which
possess sufficiently long half-lives to have survived in detectable quantities since the formation of the earth (about
3 billion years ago), with their radioactive decay products.
Rad is the conventional unit of absorbed dose (1 rad = 100 ergs/g of tissue = 0.01 Gy).
Radiation (specifically, Ionizing Radiation) refers to the energy released in the form of particles (i.e., alpha, beta,
or neutrons), electromagnetic waves (i.e., gamma photons and x rays), or both, during the radioactive decay of
an unstable atom.
Radioactivity is the property of an unstable atom of a radioactive element whereby the atom transforms (decays)
spontaneously by emission of radiation into an atom of a different element. Radioactive properties of unstable
atoms are determined by nuclear considerations only and are independent of their physical or chemical states.
Radioactive contamination is commonly used to describe radioactive atoms that are unconfined or in undesirable
locations.
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Radioactive decay is the process whereby an unstable nucleus of a radioactive atom ejects one or more particles
(i.e., alpha, beta, or neutrons) from its nucleus to establish a more stable state. These particles are sometimes
accompanied by a release of electromagnetic energy (i.e., gamma or x ray radiation). Together, ejected particles
and released energy are called radiation. Radioactive decay results in the formation of an atom of a different
element called a decay product (progeny or daughter) which also may be radioactive. There are three principal
modes of radioactive decay: alpha, beta, and neutron.
Alpha decay occurs when the neutron to proton ratio is too low and, because of this instability,
the unstable nucleus ejects an alpha particle (alpha radiation). An alpha particle has two
protons and two neutrons. Emission of an alpha particle from an atom decreases its atomic
weight by four and its atomic number by two. Thus, the new atom of another element has two
fewer protons and two fewer neutrons and its chemical properties are different from those of
its parent element. It too may be radioactive. For example, when an atom of radium-226 (with
88 protons and 138 neutrons) emits an alpha particle, it becomes an atom of radon-222 (with
86 protons and 136 neutrons), a gas. Since radon-222 is also radioactive, it too decays and
forms an atom of still another element. Alpha particles are somewhat massive and carry a
double positive charge. They can be completely attenuated by a sheet of paper.
Beta decay occurs when an electrically neutral neutron splits into two parts, a proton and an
electron. The electron is emitted as a beta particle (beta radiation) and the proton remains
in the nucleus. The atomic number of the resulting decay product is increased by one, and the
chemical properties of the progeny differ from those of its parent. Still, the atomic weight of
the decay product remains the same since the total number of neutrons and protons stays the
same, that is, a neutron has become a proton, but the total number of neutrons and protons
combined remains the same. Beta particles will penetrate farther than alpha particles because
they have less mass and only carry a single negative charge. Beta radiation can be attenuated
by a sheet of aluminum.
Neutron decay occurs during nuclear fission reactions, resulting in the emission of a neutron,
two smaller nuclei, called fission fragments, and beta and gamma radiation. In general,
neutron-emitting radionuclides are unlikely to be encountered or of much concern at most
Superfund sites.
Gamma radiation may accompany alpha, beta, or neutron decay. It is electromagnetic energy
emitted from the atomic nucleus and belongs to the same wave family as light, radio waves, and
x rays. X rays, which are extra-nuclear in origin, are identical in form to gamma rays, but have
slightly lower energies. Gamma radiation can be attenuated by heavy material such as concrete
or lead.
Radioactive Decay Series or Chains are radionuclides which decay in series. In a decay series, an unstable atom
of one radioisotope (the parent isotope) decays and forms a new atom of another element. This new atom may,
in turn, decay to form a new atom of another element. The series continues until a stable or very long-lived
atom is formed. At that point, the decay chain ends or is stopped. The number of radionuclides hi a series
varies, depending upon the number of transformations required before a stable atom is achieved. This process
can be illustrated as follows:
Nğ - N2 - N, -~ Nn (stable)
where N, is the number of atoms of the parent radioisotope decaying to form atoms of the first decay product,
N2, which in turn decays to form atoms of the second decay product, N3, which continues to decay until a stable
atom, Nn, is formed. Examples of important naturally occurring decay series include the uranium series, the
thorium series, and actinium series. There are three major reasons why it is important to identify decay series
and to characterize the properties of each decay product in those series:
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First, the total activity content (and the potential hazard) of a radioactive
source may be substantially underestimated if the activity contributions from
each of the decay products are not included. If it is assumed incorrectly that
only one radionuclide of potential concern is present hi a source when, in fact,
one or more decay products also may be present, then the total activity of and
threat posed by that source may not be considered completely;
Second, decay products may be more toxic, either alone or in combination,
than the parent nuclide. Because each radioactive isotope possesses its own
unique chemical, physical, and radioactive properties, the hazard presented by
decay products may be substantially greater than that posed by the parent
nuclide alone.
And third, the environmental fate, transport, and bioaccumulation
characteristics of the decay products may be different from those of the parent
nuclide. All relevant migration pathways for both the parent nuclide and
decay products must be considered to account for site threats.
Radioactive equilibrium refers to the activity relationship between decay series members. Three types of
radioactive equilibrium can be established: secular, transient, and no equilibrium. Secular equilibrium refers
to the state of equilibrium that exists when series radioisotopes have equal and constant activity levels. This
equilibrium condition is established when the half-life of the parent isotope is much greater than that of its decay
product(s) (i.e., T1/2 of the parent >ğ T1/2 of the decay product, or when expressed in decay constants, Xj >ğ
X,). Transient equilibrium is the state of equilibrium existing when the half-life of the parent isotope is slightly
greater than that of its decay product(s) (i.e., T1/2 of the parent > T1/2 of the decay product, or X2 > X,) and the
daughter activity surpasses that of the parent. No equilibrium is the state that exists when the half-life of the
parent isotope is smaller than that of the decay product(s) (i.e., X2 < X,). In this latter case, the parent activity
will decay quickly, leaving only the activity of the decay product(s).
Radioactive half-life (Tiq) (sometimes referred to as the physical half-life) is the time required for any given
radioisotope to decrease to one-half its original activity. It is a measure of the speed with which a radioisotope
undergoes nuclear transformation. Each radioactive isotope has its own unique rate of decay that cannot be
altered by physical or chemical operations. For example, if one starts with 1,000 atoms of iodine-131 (1-131) that
has a half-life of 8 days, the number of atoms of 1-131 remaining after 8 days (one half-life), 16 days (two half-
lives), and 24 days (three half-lives) will be 500, 250, and 125, respectively. In fact, the fraction of the initial
activity of any radioisotope remaining after n half-lives can be represented by the following relationship:
A - _L
AO 2"
where A,, is the initial activity and A is the activity left after n half-lives. After one half-life (n= 1), 0.5 (or 50%)
of the initial activity remains; after three half-lives (n=3), 13% remains; and after five half-lives (n=5), 3%
remains. Further, the activity of any radioisotope is reduced to less than 1% after 7 half-lives. For radioisotopes
with half-lives greater than six days, the change in activity in 24 hours will be less than 10%. Over 1,600 different
radioisotopes have been identified to date, with half-lives ranging from fractions of a second to billions of years.
Radioactive isotopes (radioisotopes or radionuclides) are radioactive atomic variations of an element. Two
radioactive isotopes of the same element have the same number of protons but different numbers of neutrons.
They share common chemical properties, but exhibit different and unique radioactive, and possibly physical,
properties because of the differences in their respective nuclear stabilities and decay modes.
Radionuclide slope factor is the lifetime excess cancer incidence rate per unit intake of (or per unit exposure
to) a given radionuclide.
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Rem is the acronym for roentgen equivalent man and is the unit of dose equivalent (1 rem = 0.01 Sv).
Roentgen (R) is a unit of external exposure which refers to the number of ionizations occurring in a unit mass
of air due to the transfer of energy from a gamma or x radiation field emitted by a radioactive source. The unit
is expressed as coulombs of charge per kilogram of air (1 R = 2.58 x 10"* C/kg). Commonly used subunits of
the roentgen are the milliroentgen (mR = 10'3 R) and the microroentgen (jjR = 10'6 R), with corresponding
subunits of mR/hr or pR/hr for exposure rates. The roentgen may be used to measure gamma or x radiation
only. [See Exposure and Exposure Rate.]
System International (SI) is the international system of radiation measurements and units.
Sievert (Sv) is the SI unit for dose equivalent (1 Sv = 100 rem).
Specific activity (SpA) relates the number of curies per gram of a given radioisotope, as follows:
1.3JC108
SpA (dig) =
(half-life, days) (atomic weight)
For example, the SpA for the long-lived, naturally occurring uranium isotope U-238 (half-life, 4.51 x 109 years)
is 3.3 x 10'7 Ci/g, whereas the SpA for the short-lived phosphorous isotope P-32 (half-life, 14.3 days) is 2.9 x V?
Ci/g. Expressed in another way, one Ci of U-238 weighs 3 megagrams ( 3 x 106 grams), whereas one Ci of P-32
weighs 3.4 micrograms (3.4 x 10"6 gram). From this example it is clear that the shorter the half-life (i.e, the
faster the disintegration rate) of a radioisotope, the smaller the amount of material required to equal a curie
quantity; conversely, the longer the half-life of a radioisotope, the larger the amount of material required to
obtain a curie amount. The specific activity of a radioisotope is one major factor determining its relative hazard.
Specific ionization is the number of ion pairs produced by ionizing radiation per unit path length. The number
of ion pairs produced depends on the mass and charge of the incident radiation. Because of their somewhat
massive size and charge, alpha particles create more ion pairs than do beta particles, which, in turn, create more
ion pairs than do gamma photons. Since it may take more than one ionizing collision to absorb a radiation
particle or photon, particulate or electromagnetic radiation may produce several ion pairs.
Total ionization is the total number of ion pairs produced by ionizing radiation in a given media (e.g., air or
biological material).
Ubiquitous manmade radionuclides are those radionuclides, naturally occurring or synthetic, generated by man' s
activities and widely distributed in the environment.
Working level (WL) is a special unit used to describe exposure to the short-lived radioactive decay products of
radon (Rn-222) and is defined as any combination of radon decay products in one liter of air that will result in
the ultimate emission of 1.3 x 103 MeV of alpha energy.
Working level month (WLM) is the exposure to 1 WL for 170 hours (1 working month).
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APPENDIX II
Radioactive Substances in the Environment
This appendix identifies potential sources, properties, and pathways of radioisotopes in the environment to provide
the reader with a useful context for discussions of measurement techniques and their application to HRS scoring.
In general, radioactive sources at Superfund sites contain either naturally occurring radionuclides or manmade
radionuclides, or both, in varying concentrations and physical and chemical forms.
Radionuclides present in the natural environment can be divided into three groups according to origin:
(1) Naturally occurring radionuclides are those terrestrial radionuclides (and their
decay products) of primordial origin with half-lives comparable to the age of the
earth (about 3 billion years);
(2) Cosmic radiation and cosmogenic radionuclides consist of primary charged
and neutral particles that bombard the earth's atmosphere and the secondary
particles generated by the primary particles in the earth's atmosphere; and
(3) Ubiquitous manmade radionuclides are those radionuclides generated by man's
activities and widely distributed in the environment.
Group #1: Naturally Occurring Radionuclides
Naturally occurring terrestrial radionuclides include several dozen or more radionuclides of the uranium, thorium,
and actinium series that decay in series to eventually form isotopes of stable lead. Also included among the
naturally occurring radionuclides are a group of "non-series" radioisotopes, e.g., H-3, K-40, and Rb-87, that decay
directly to a stable isotope. Uranium-238, U-235, and Th-232 head the uranium, actinium, and thorium series,
respectively. Each of these series can be further divided into several subseries based on the differences in the
radioactive and physical properties of their progeny, as discussed below. When the decay members of these series
are not subjected to either chemical or physical separation processes in the environment, a state of secular
equilibrium may be achieved whereby the all series members decay at the same rate as the parent nuclide heading
the series. More often, however, series members separate from each other in the environment to some extent due
to their differing physical and chemical properties. As a result, varying degrees of activity disequilibrium can occur
among series members.
Uranium Series
The members of the uranium series are shown in Exhibit 1 along with their respective radioactive half-lives and
principal decay modes. Uranium-238, which heads this series, constitutes 99.28% by weight of the four isotopes
of uranium with mass numbers 230, 234, 235, and 238 found in nature. By comparison, the natural abundances
of U-234 and U-235 are only 0.0058% and 0.71 %, respectively.
The first uranium subseries consists of the radioisotopes U-238, Th-234, Pa-234m, and U-234. In general, all four
isotopes are found together in equal activity concentrations (i.e., secular equilibrium) under a wide range of
environmental settings. However, less than equal activity concentrations of U-238 and U-234 have been reported
by several investigators, indicating that some separation of these isotopes may occur in the environment. For
example, Rosholt et al. (Ro66) reported a ^U/^U activity ratio as low as 0.58 in a soil horizon weathered to clay,
and Smith and Jackson (Sm69) reported activity ratios of 0.914 to 0.985 in 16 widely distributed sources. A
uranium activity ratio of 1.1 in water was determined from samples taken from the Atlantic, Pacific, and Indian-
Oceans (Ro64). Because of the large variability that can exist in uranium isotope activity ratios, it is very important
to determine the degree of isotopic equilibrium between U-234 and U-238 in media samples on a site-specific basis.
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Exhibit 1. Uranium Decay Series*
Radio isotope
(atomic *)
U-238
(92)
1
Th-234
(90)
4
Pa-234m'
(91)
4
U-234
(92)
4
Th-230
(90)
4
Ra-226
(88)
1
Rn-222
(86)
4
Po-218'
(84)
4
Pb-214
(82)
4
Bi-214'
(83)
4
Po-214
(84)
4
Pb-210
(82)
4
Bi-210
(83)
4
Po-210
(84)
4
Pb-206
(82)
Historical
name
Uranium I
Uranium X,
Uranium X2
Uranium II
Ionium
Radium
Radon
(gas)
Radium A
Radium B
Radium C
Radium C '
Radium D
Radium E
Radium F
Radium G
Half -life"
4.51 x 10' y
24.1 d
1.17m
2.47 x 105y
8.0 x 104 y
1602y
3.82 d
3.05 m
26.8 m
19.7 m
164//S
21 y
5.01 d
138.4 d
Stable
Major radiation energie* (MeV)
and intensities""
a
4.15 (25%)
4.20 (75%)
4.72 (28%)
4.77 (72%)
4.62 (24%)
4.68 (76%)
4.60 (6%)
4.78 (95%)
5.49 (100%)
6.00 (-100%)
5.45 (0.012%)
5.51 (0.008%)
7.69 (100%)
4.65 (0.00007%)
4.69 (O.OOO05%)
5.305 (100%)
"~
ft
...
0.103 (21%)
0.193 (79%)
2.29 (98%)
,0.33 (-0.02%)
0.65 (50%)
0.71 (40%)
0.98 (6%)
1.0 (23%)
1.51 (40%)
3.26 (19%)
0.016 (85%)
0.061 (15%)
1.161 (-100%)
K
...
0.063C (4%)
0.093C (4%)
0.765 (0.3%)
1.001 (0.6%)
0.53 (0.2%)
0.068 (0.6%)
0.142 (0.07%)
0.186 (4%)
0.510 (0.07%)
0.295 (19%)
0.352 (36%)
0.609 (47%)
1.120 (17%)
1.764 (17%)
0.799 (0.014%)
0.047 (4%)
0.803 (0.0011%)
* Source: Lederer and Shirley (1978) and Shleien and Terpilak (1984).
" Half-life given in seconds (s), minutes (m), days (d), or years (y).
'" Intensities refer to percentage of disintegrations of the nuclide itself, not to the parent of the series.
t Approximately O.I3% of all Pa-234m £ particle emissions form an intermediate radioisotope, Pa-234 (6.75 hrs: ^-emitter),
before decaying to U-234. For Po-218, 0.02% decays through At-218 (-2 sec: or-emitter) before forming Bi-214. For Bi-214,
0.02% decays through TI-210 (1.3 m: ^-emitter) to Pb-210.
46
-------
The second uranium subseries, headed by U-234, includes Th-230 and Ra-226. In general, the activity
concentrations of Th-230 and Ra-226 measured in most soils and rocks are comparable to those of U-238 and U-
234, suggesting that Th and Ra do not tend to migrate from either of their uranium precursors under stable
conditions. This may not be true in the case of ground water, surface water, or sediments. For example, Rosholt
et al. (Ro66) reported that the disequilibrium between Th-230 and U-238 or U-234 may range by a factor of two
in sea water and enhanced in sediments. Other evidence suggests that Ra-226 is readily mobile in natural waters,
either due to recoil or breakdown of entrapping solids. A common place for accumulation of radium isotopes is
in the calcium carbonate "sinter" deposited at the orifices of, and with the out-wash from, hot springs. Such
locations typically show little activity from the uranium precursors. In other environmental settings, Ra-226
demonstrates a strong affinity for anions, particularly sulfate. Thus, in uranium deposits that have been subjected
to strong sulfuric acid water produced by the oxidation of ferrous sulfide, low concentrations of Ra-226 are present.
The third subseries, headed by Ra-226, consists of Rn-222, a noble gas, and its short half-life progeny, Po-218,
Pb-214, Bi-214, and Po-214. Due to its inert gas structure and relatively long radioactive half-life, Rn-222 is highly
mobile in the environment. The short-lived radon progeny are readily ionized and are attracted to dust particles
in the air or to clay minerals in soil. In general, Rn-222 and its short half-life progeny quickly establish equilibrium
activity concentrations in most samples.
The final subseries consists of the longer-lived radon decay products, Pb-210, Bi-210, and Po-210, and terminates
with the formation of stable Pb-206. Due primarily to the migration of Rn-222, Pb-210 concentrations in
environmental media are highly variable. Variable concentrations of Po-210 are also common due to its chemical
properties.
Actinium Series
Uranium-235 heads the actinium series shown in Exhibit 2. Similar to the uranium series, the actinium series also
includes radionuclides with half-lives long enough to permit disequilibrium conditions. Rosholt (Ro59) considers
all progeny of U-235 to be a single group headed by Pa-231, which he has shown to be out of equilibrium with U-
235. The short half-life of Ra-223 (11.4 days) usually precludes any significant disequilibrium between itself and
its parent Pa-231. For the case of radium deposits from ground water, a separate subgroup headed by Ra-223 and
ending with stable Pb-207 is often considered. Disequilibrium due to migration of the noble gas Rn-219 is local
due to its 4 second half-life.
Thorium Series
The thorium series (Exhibit 3), headed by Th-232, comprises a number of somewhat short-lived progeny. Given
no migration of these progeny, the series reaches secular equilibrium in 60 years in minerals, rocks, and soils of
low permeability. In highly permeable soils, waters, natural gas, petroleum, and the atmosphere, the chemical and
physical properties of the progeny can cause disequilibrium.
The thorium series may be divided into three subseries. The first subseries consists of Th-232 only, the least mobile
of the series radionuclides. This radioisotope exists naturally as a very stable oxide and is strongly adsorbed on
silicates (C176). The second subseries consists of Ra-228, Ac-228, Th-228, and Ra-224. The equilibrium of this
subseries is governed by radioactive recoil, adsorption, and changes in carrier compounds with which the
radionuclides become associated. Thoron, Rn-220, and its progeny down to stable Pb-208 make up the third
possible subseries. As with the actinium series, disequilibrium caused by migration of the noble gas Rn-220 is
unlikely due to the short half-life of Rn-220 (55 second).
Non-Series Radionuclides
Exhibit 4 lists 7 of the 17 naturally occurring radionuclides that decay to stable isotopes. Of the 17, 15 have
combinations of half-lives, isotopic abundances, and elemental abundances which result in their having insignificant
specific activities. Only K-40, Rb-87 and H-3 occur in significant concentrations in nature. K-40 and Rb-87 are
alkali metals and Rb-87 is found in nature as a replacement for potassium in minerals.
47
-------
Exhibit 2. Actinium Decay Series*
Radioisotope
(atomic tt)
U-235
(92)
^
Th-231
(90)
i
Pa-231
(91)
1
Ac-227'
(89)
Th-227
(90)
1
Ra-223
(88)
*
Rn-219
(86)
1
Po-215'
(84)
i
Pb-21 1
(82)
1
Bi-211 '
(83)
TI-207
(81)
I
Pb-207
(82)
Historical
name
Actinouranium
Uranium Y
Protactinium
Actinium
Radioactinium
Actinium X
Actinon
(gas)
Actinium A
Actinium B
Actinium C
Actinium C ' '
Actinium D
Half-life"
7.1 x 10s y
25. 5 h
3.25x 104y
21. 6y
18.2 d
11.43d
4.0 s
1.78 ms
36.1 m
2.15 m
4.79m
Stable
Major radiation energies (MeV)
and intensities'"
a
4.37 (18%)
4.40 (57%)
4.58c (8%)
...
4.95 (22%)
5.01 (24%)
5.02 (23%)
4.86c (0.18%)
4.95 (1.2%)
5.76 (21%)
5.98 (24%)
6.04 (23%)
5.61 (26%)
5.71 (54%)
5.75 (9%)
6.42 (8%)
6.55(11%)
6.82(81%)
7.38 (-100%)
6.28 (16%)
6.62 (84%)
...
ft
...
0.140 (45%)
0.220 (15%)
0.305 (40%)
...
0.043 (-99%)
0.74
(-0.0002%)
0.29 (1.4%)
0.56 (9.4%)
1 .39 (87.5%)
0.60 (0.28%)
1.44(99.8%)
Y
0.143 (11%)
0.185 (54%)
0.204 (5%)
0.026 (2%)
0.084c (10%)
0.027 (6%)
0.29c (6%)
0.70 (0.08%)
0.050 (8%)
0.237c (15%)
0.3 1c (8%)
0.149c (10%)
0.270(13%)
0.33c (6%)
0.272 (9%)
0.401 (5%)
"
0.405 (3.4%)
0.427 (1.8%)
0.832 (3.4%)
0.351 (14%)
0.897 (0.16%)
" Source: Lederer and Shirley (1978) and Shleien and Terpilak (1984).
'" Half-life given in seconds (s), minutes (m), days (d), or years (y).
Intensities refer to percentage of disintegrations of the nuclide itself, not to the parent of the series.
t Approximately 1.4% of all Ac-227 emissions form an intermediate radioisotope, Fr-223 (22 m: jff-emitter), before
decaying to Ra-223. For Po-215, 0.00023% decays through At-215 (~ 0.1 msec: o-emitter), before forming Bi-
211. For Bi-211, 0.28% decays through Po-211 (0.52 sec: /J-emitter) to Pb-207.
48
-------
Exhibit 3. Thorium Decay Series*
Radioisotope
(atomic #)
Th-232
(90)
*
Ra-228
(88)
1
Ac-228
(89)
Th-228
(90)
*
Ra-224
(88)
1
Rn-220
(86)
i
Po-216
(84)
Pb-212
(82)
1
Bi-212'
(83)
I 1
(64%) (36%)
i 1
Po-212 i
(84) 1
1 1
* TI-208
i (81)
1 1
Pb-208
(82)
Historical
name
Thorium
Mesothorium 1
Mesothorium II
Radiothorium
Thorium X
Thoron
(gas)
Thorium A
Thorium B
Thorium C
Thorium C'
Thorium C "
Thorium D
Half-life"
1.41 x 10'° y
6.7 y
6.13 h
1.910y
3.64d
55 s
0.15 s
10.64 h
60.6 m
304 ns
3.01 m
Stable
Major radiation energies (MeV)
and intensities'"
a
3.95 (24%)
4.20 (75%)
...
5.34 (28%)
5.43 (71%)
5.45 (6%)
5.68 (94%)
6.29 (100%)
6.78 (100%)
6.05 (25%)
6.09 (10%)
8.78 (100%)
P
...
0.005 (100%)
1.18 (35%)
1.75 (12%)
2.09 (12%)
0.346 (81%)
0.586(14%)
1 .55 (5%)
2.26 (55%)
0.98 (6%)
1.28 (25%)
1.52(21%)
1 .80 (50%)
Y
...
0.34c(15%)
0.908 (25%)
0.96c (20%)
0.084(1.6%)
0.214 (0.3%)
0.241 (3.7%)
0.55 (0.07%)
0.239 (47%)
0.300 (3.2%)
0.040 (2%)
0.727 (7%)
1.620 (1.8%)
0.511 (23%)
0.583 (86%)
0.860 (12%)
2.614 (100%)
' Source: Lederer and Shirley (1978) and Shleien and Terpilak (1984).
Half-life given in seconds (s), minutes (m), hours (h), days (d), or years (y).
'" Intensities refer to percentage of disintegrations of the nuclide itself, not to the parent of the series.
t Percentages in brackets are branching fractions.
49
-------
Exhibit 4. Non-Series Naturally Occurring Radioisotopes*
Radioisotope
(atomic #)
K-40
(19)
Rb-87
(37)
La-138
(57)
Sm-147
(62)
Lu-176
(71)
Re-187
(75)
Name
(elemental
abundance)
Potassium
(0.0118%)
Rubidium
(27.85%)
Lanthanum
(0.089%)
Samarium
(15.07%)
Lutetium
(2.6%)
Rhenium
(62.9%)
Half-life"
1.3 x 109 y
4.7 x 10'° y
1.1 x 10" y
1.1 x 10" y
2.2 x 1010 y
4.3 x 10loy
Major radiation energies (MeV)
and intensities'"
a
...
...
...
2.2 (100%)
_
P
1.314 (89%)
0.274 (100%)
0.21 (100%)
0.43 (100%)
0.043 (100%)
Y
1.46 (11%)
0.81 (30%)
1 .43 (70%)
0.088 (15%)
0.202 (85%)
0.306 (95%)
Source: Lederer and Shirley (1 978).
Half-life given in years (y).
Intensities refer to percentage of disintegrations of the nuclide itself.
50
-------
Distribution of Naturally Occurring Radionuclides:
In Rocks
The source of the primordial radionuclides is the earth's crust and underlying plastic mantle. Because of
sedimentary processes sorting the products of weathering, several major types of sedimentary rock (shales,
sandstones, and carbonate rocks) develop that differ significantly in radionuclide concentrations:
Shales are composed of fine grains of clay (normally 35%), silt, or mud
obtained from the breakdown of other rock. A significant fraction of shale
contains potassium as a major constituent. All shale can adsorb the series
radionuclides. The radionuclides also may be present in the cement that binds
the shale together. Mean values for common shales are 2.7 percent potassium,
12 ppm thorium, and 3.7 ppm uranium (C166).
Sandstones are composed of medium-sized grains, usually of quartz (SiOj), that
contain little in the way of radioactive impurities. Sandstone consisting of
quartz grains bound with quartz cement is one of the least radioactive rocks.
Such sandstone may contain less than 1 percent potassium, less than 2 ppm
thorium, and less than 1 ppm uranium. Arkoses - sandstones that contain
greater than 25 percent potassium-bearing feldspar - may contain upwards of two
to three percent potassium. Clark et al. (Cl 66) report averages of 6.4 ppm
thorium and 3.0 ppm uranium for modern beach sands. Thus, sandstone made
from beach sand may be high in the series nuclides. In general, sandstones are
low in both series and non-series radionuclides.
Carbonate rocks (limestone and dolomites), derived by chemical precipitation
from water or by accumulation of shells, bones, and teeth of organisms, are low
in radionuclide content. Still the intergranular spaces contain a variety of
elements characteristic of the sea water where most radionuclides may be
deposited. Carbonate rocks are low in potassium due to the high solubility of
potassium salts, and are low in thorium because it is highly depleted in sea
water. Uranium becomes fixed by the reducing conditions prevailing in the
decaying organic matter at the sea bottom and thus becomes incorporated in the
carbonate rocks.
Exhibit 5 provides summary data on the average concentrations of K-40, Rb-87, Th-232, and U-238 in various types
of rocks and sediments.
In Soil
Radionuclides in soil are derived from source rock. In most cases, soil activity concentrations are often less than
source rock concentrations due to water leaching, dilution as a result of the soil's increased porosity, and the
addition of organic matter and water. In addition, biochemical processes taking place during soil development also
tend to reduce the radionuclide concentrations in comparison to the source rock. However, in some cases, soil
radioactivity may be augmented by sorption or precipitation of radionuclides from incoming water, by redistribution
of wind-blown soils, or by activities such as adding fertilizer or importing top soil to a location. Exhibit 5 provides
summary data on average concentrations of K-40, Rb-87, Th-232, and U-238 in soil.
In the Hydrosphere
The concentrations of naturally occurring radionuclides in water are several orders of magnitude less than those in
rocks and soils. Potassium-40 is one of the more abundant radionuclides in most water systems. For uranium and
thorium series isotopes, there is a shift away from equilibrium between parent radionuclides and progeny.
Concentrations of uranium and Rn-222 daughters are frequently observed to be elevated compared to Ra-226 levels.
51
-------
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52
-------
Elevated Rn-222 concentrations, ranging from several hundreds to several thousands of pCi/L, are often found in
ground water samples, whereas Ra-226 concentrations in the same sample are typically a factor of 1000 lower.
Radium and thorium isotopes tend to concentrate in bottom sediments.
Radionuclide concentrations of fresh water bodies and urban water supplies vary widely depending on local geology,
hydrology, geochemistry, and radionuclide soil concentrations. Sea water, on the other hand, exhibits a rather
narrow range of activity concentrations (Ko62, Ch86).
In the Atmosphere
The level of radioactivity in air and soil water is due primarily to Rn-222, Rn-220, Rn-219, and their decay
products. Approximately 35 percent of the Rn-222 produced from Ra-226 in soil emanates into soil pore spaces,
resulting in a Rn-222 concentration of about 500 pCi/L of pore fluid per ppm of U-238 in equilibrium with Ra-226
(NCRP87b). At a soil concentration of 1-2 ppm of U-238, Rn-222 levels in soil pores range 102 to 103 pCi/L,
several orders of magnitude greater than typical atmospheric levels. Atmospheric radon concentrations depend on
the amount of radon exhaled by the soil and on atmospheric factors that control its upward dispersion. Rn-222
measurements outdoor show that the mean concentrations can range from 100 to 1100 pCi/m3 (NCRP87b). Exhibit
6 summarizes typical concentrations of naturally occurring radionuclides in the atmosphere.
In the Biosphere
Potassium-40 is the most abundant radionuclide in the biosphere. Concentrations of other naturally occurring
radionuclides in plants and animals are highly variable and are almost never in equilibrium (NCRP76). For
example, Ra-226 is preferentially taken up by plants relative to U-238 or U-234. In general, activity concentrations
in plants range from 1 to 50 pCi/g for "°K, from 0.01 to 10 pCi/g for Po-210, and are about 0.1 pCi/g for Rb-87
(NCRP76), as shown in Exhibit 7.
Group #2: Cosmic Radiation and Cosmogenic Radionuclides
Cosmic radiation consists of primary charged and neutral particles that bombard the earth's atmosphere and the
secondary particles (e.g., H-3 and C-14) generated by the primary particles in the earth's atmosphere. Primary
cosmic radiation, produced by supernovas and solar flares, is composed of approximately 87 percent photons, 11
percent alpha particles, 1 percent heavier nuclei, and 1 percent electrons with energies up to at least 1030 eV
(average energy is 108 to 10" eV). Secondary cosmic particles are produced by a variety of spallation and neutron
activation reactions, mostly with the nuclei of argon, nitrogen, and oxygen.
Cosmic radiation increases with altitude as the mass of the atmosphere decreases. Cosmic flux density is least near
the geomagnetic equator and increases with latitude. At sea level, the flux density is about 10% lower at the equator
than at high latitudes. Energetic solar flares generate large numbers of photons that can penetrate the earth's
magnetic field and add to the cosmic ray flux density incident on the atmosphere. These bursts seldom produce
significant effects at ground level. There is evidence for an 11-year cycle in mean solar activity that produces a
modulation of the cosmic radiation reaching the earth's atmosphere. At ground altitudes, the effect is about 10
percent.
Exhibit 8 shows the typical environmental radiation field at 1 meter above sea level due to cosmic and terrestrial
radionuclides.
A total of 20 radionuclides are produced by cosmic rays in the earth's atmosphere. From the point of view of
radiation measurements and doses, only carbon-14 (C-14) and, to a lesser extent, tritium (H-3) are worth
considering.
53
-------
Exhibit 6. Radionuclides In The Atmosphere*
Radionuclide
Uranium series:
Rn-222
Pb-214
Bi-214
Pb-210
Po-210
Thorium series:
Rn-220
Pb-212
Others:
Kr-85
Be-7
Surface air content
Typical range
(pCi/m3)
20 - 500
0-500
0-500
0.003 - 0.03
-
~
0.5 - 10
0.02 - 0.20
Mean value
(pCi/m3)
120
100
100
0.01
0.003
100
2
17
0.06
Source: NCRP (1976): Table 2-8.
54
-------
Exhibit 7. Total Natural Radioactivity In Plants*
Radiation
Gross alpha
Gross beta
K-40
Rb-87
Po-210
Concentration
(pCi/g gross weight)
0.14 - 3.1
7.8 - 123
1-50
-0.1
0.01 - 10
Source
mainly as Po-210; other U + Th
series nuclides
mainly as K-40; Pb-210; Bi-210;
other U + Th series nuclides
--
~
--
Source: NCRP (1976): Table 2-9b.
55
-------
Exhibit 8. Typical Environmental Radiation Field (One Meter Height)*
Radiation
alpha
beta
gamma
neutron
proton
muons
Energy
(MeV)
1 -9
0.1 -2
0.1 -2
2-200
<2.4
<1.5
<2.4
<2.6
<0.8
0.1 - 100
10 - 2,000
100 - 30,000
Source
radon (atm)
radon (atm)
K, U, Th, Sr (soil)
cosmic rays
radon (atm)
K (soil)
U (soil)
Th (soil)
Cs + other fallout (soil)
cosmic rays
Absorbed dose rate in free
air (microrad/hr)
2.7
0.2
2.5
0.7
0.2
2.0
1.0
2.4
0.3
0.1
Total: 14.5
Source: NCRP (1976): Table 2-10.
56
-------
Tritium (H3)
Tritium, a radioactive isotope of hydrogen, is a beta emitter (average energy 5.69 keV) with a radioactive half-life
of 12.3 years. It occurs naturally in the surface waters of the earth as a product of the atmospheric interaction of
high-energy cosmic rays with nitrogen and oxygen gases (UN72, NCRP79). Its annual production rate is
approximately 2 megacuries (MCi), resulting in a steady-state inventory of about 30 MCi in the biosphere. Since
1954, large amounts of manmade tritium have been released into the environment primarily from nuclear weapons
testings, discharges from nuclear power plants (Exhibit 10), and some nuclear weapons production plants. Tritium
is used as a radioactive luminizing material in consumer products, such as watches, clocks, and emergency signs,
and as a component of nuclear weapons.
Prior to the injection into the biosphere from nuclear tests, levels of H-3 in waters of the mid-latitude regions of
the earth were in the range of 6 to 24 pCi/L. The amount of tritium added to the global inventory as a result of
nuclear weapons testing is discussed under the next section on manmade radionuclides. About 90 % of natural H-3
resides in the hydrosphere, 10% in the stratosphere, and only 0.1 % in the troposphere. The low inventory of H-3
in the troposphere is due to the fact that tritium in the form of HTO is rapidly washed out by rain, with an estimated
residence time of between 20 to 40 days.
Carbon-14 (C-14)
Carbon-14 is the one of the three isotopes of carbon: C-12 (99.8%), C-13 (1.1%), and C-14 (0.1%). It is a pure
beta-emitting radionuclide (average energy 50 keV) with a radioactive half-life of 5,730 years. Natural C-14 is
produced in the upper atmosphere by interaction of cosmic-ray neutrons with nitrogen. Its production rate is not
accurately known, but may correspond to about 0.03 MCi per year with a steady-state inventory of approximately
280 MCi (UN72). Similar to tritium, C-14 has been produced in significant quantities by nuclear weapons testing
and discharges from nuclear power plants (see the section on manmade radionuclides).
As an isotope of carbon, C-14 is involved with all biological and geochemical process on earth. It is present in the
atmosphere as carbon dioxide, in the terrestrial biosphere as incorporated carbon, and in surface waters as dissolved
bicarbonates. The concentration of C-14 in the environment varies widely. At present, the United Nations assumes
a specific activity of 6.1 pCi/g in the terrestrial biosphere (UN 72).
Group #3: Ubiquitous Manmade Radionuclides
Manmade radioisotopes that are widely distributed in the environment are due primarily to releases from nuclear
weapons testing and nuclear power facilities. Exhibits 9 and 10 list some of the important radionuclides produced
by these processes.
Radionuclides released during nuclear weapons testing: Since the first test of a nuclear weapon at Alamagordo,
New Mexico, in 1945, approximately 450 additional nuclear weapons have been detonated in the atmosphere. These
detonations resulted in the production and global dispersal of several millions of curies of radioactive fission and
activation products, transuranic elements, and unfissioned uranium and plutonium isotopes.
These detonations also significantly increased natural concentrations of H-3 and C-14. Between 1,900 to 8,000 MCi
of H-3 were added to the northern hemisphere by nuclear weapons testing through 1963 (Er65, Mi71). As a result,
average concentrations of H-3 in surface waters in the U.S. rose from 3 to 16 pCi/L to about 4,000 pCi/L in 1963
(Be73). Today, tritium concentrations due to fallout H-3 have decreased below the level due to natural H-3
(NCRP79). By the end of 1962, nuclear testing had increased the atmospheric concentration of C-14 to about twice
its pre-1950 concentration of 6 pCi/g. Because of exchange with the ocean and to a lesser extent the biosphere,
C-14 concentrations in the atmosphere due to weapons testing dropped to about 3 pCi/g by the end of 1970
(NCRP87b). The increase in C-14 concentrations in the ocean has been greatest in the surface waters since C-14
has a residence time of three to eight years in the mixing layers before it is transferred below the thermocline.
Because it takes a few thousand years before C-14 reaches the ocean floor, there is no increase in C-14
concentrations for deep ocean sediments.
57
-------
Strontium-90 and Cs-137 are two of the most important fission products that were widely distributed in near-surface
soils because of the weapons testing. Measurable concentrations of Sr-90 and Cs-137 in soil exist today. These
concentrations are distributed almost exclusively in the upper 15 cm of soil and decrease roughly exponentially with
depth.
Radionuclides released from nuclear power stations: Releases of radionuclides produced by nuclear fission in
boiling water reactors (BWRs) and in pressurized water reactors (PWRs) occur because of periodic fuel failure,
defects, or corrosion that results in transfer of some fission and activation products into the reactor coolant. In
PWRs, the primary coolant is in a sealed loop that is continually purged for control of chemical composition and
purification. Gaseous wastes released in the process are held in tanks for between 30 to 120 days to allow short-
lived nuclides to decay prior to release. Other gaseous effluent streams originate from the condenser exhaust on
the steam circuit, secondary coolant blowdown, reactor building ventilation (including containment purges), and
turbine plus ancillary building ventilation (UN82). In BWRs, the main condenser air-ejector system continuously
removes non-condensible gases from the steam flow. This is the main source of noble gases released with the
gaseous waste stream. Secondary pathways include the purging system for the turbine gland seals, the condenser
mechanical vacuum pump, and any process fluid leaks to ventilated buildings.
Radionuclides released to the atmosphere include noble gases (argon, krypton, and xenon), C-14, tritium, iodines,
and participates. Radionuclides discharged in liquid effluents include tritium, fission products, and activated
corrosion products. Exhibit 10 lists the nuclide composition of typical liquid and gaseous effluents for PWRs and
BWRs in the U.S. Compositions often vary depending on waste treatment methods employed, the age and condition
of the plant, etc. Release rates are not listed for the nuclides since these data vary greatly from plant to plant.
Environmental monitoring programs typically show that the nuclides in the effluents are not readily detectable in
the environment except near the point of release.
58
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Exhibit 9. Ubiquitous Manmade Radioisotopes*
Radio isotope
(atomic *)
H-3
(1)
C-14
(6)
Mn-64
(25)
Fe-56
(26)
Co-60
(27)
Zn-66
(30)
Kr-85
(36)
Sr-90 (38)-
Y-90 (39)
Zr-95
(40)
Nb-95
(41)
Ru-106 (44) -
Rh-106 (45)
Sb-125 (51) -
Te-125m (52)
1-129
(53)
Cs-134
(55)
Name
(Origin)t
Tritium
(NE, Nf)
Carbon
(NE, FF)
Manganese
(NE)
Iron
(NE)
Cobalt
(NE, NF)
Zinc
(NE, NF)
Krypton
(NE, NF)
Strontium -
Yttrium
(NE, NF)
Zirconium
(NE)
Niobium
(NE)
Ruthenium -
Rhenium
(NE, NF)
Antimony -
Tellurium
(NE)
Iodine
(NF)
Cesium
(NE, NF)
Half-life"
12.3 y
5730 y
303d
2.6 y
5.26 y
245 d
10.76 y
28 y (Sr)
64 h (Y)
65.5 d
35 d
368 d (Ru)
30 s (Rh)
2.77y (Sb)
58 d (Te)
1.7 x 107 y
2.05 y
Major radiation energies (MeV)
and Intensities'"
a
...
...
...
...
...
...
-
...
...
...
...
...
JB
0.0186 (100%)
0.156 (100%)
1.48 (0.12%)
0.314 (99%)
/}+: 0.327
(1.4%)
0.173 (0.4%)
0.687 (99.6%)
0.546 (100% Sr)
2.27 (100% Y)
0.366(55%)
0.398 (44%)
0.160 (99.9%)
0,039 (100% Ru)
3.54 (79% Rh)
0.61 (14% Sb)
0.150 (100%)
0.662 (100%)
r
...
...
0.835 (100%)
0.23 (0.004%)
1.17 (100%)
1.33 (100%)
0.511 (3.4%)
1.12 (49%)
0.514 (0.4%)
...
0.724 (49%)
0.756 (49%)
0.765 (100%)
0.512(21%)
0.622 (11%)
1.05 (1.5%)
0.153 (62% Te)
0.176 (6% Sb)
0.270 (25% Te)
0.427 (10% Sb)
0.599 (24% Sb)
0.634 (11% Sb)
0.66 (3% Sb)
0.92-1.14 (36%
Te)
1.22 (67% Te)
2.09 (4% Te)
0.040 (9%)
0.57 (23%)
0.61 (98%)
0.796 (99%)
59
-------
Exhibit 9 - Continued
Radio isotope
(atomic *)
Cğ-137 (55) -
Bo-137m (56)
Ce-144(58) -
Pr-144 (59)
Pu-238
(94)
Pu-239
(94)
Pu-240
(94)
Pu-241 (94) -
Am-241 (95)
Name
(Origin)t
Cesium -
Barium
(NE, NF)
Cerium -
Praseodymium
(NE)
Plutonium
(SNAP, NE)
Plutonium
(NE, NF)
Plutonium
(NE, NF)
Plutonium -
Americium
(NE, NF)
Half-life"
30 y (Cs)
2.55 m (Ba)
284 d (Ce)
17.3m (Pr)
87 y
2.439 x 104 y
6580 y
13d (Pu)
458 y (Am)
Major radiation energies (MeV)
and intensities'"
a
...
5.50 (72%)
5.46 (28%)
5.155 (73%)
5.143 (15%)
5.105 (12%)
5.1683 (76%)
5.1238 (24%)
4.90 (0.002%
Pu)
4.85 (0.003%
Pu)
5.3884 (1.6%
Am)
5.443 (12.8%
Am)
5.486 (85% Am)
ft
0.514 (95% Cs)
1.176 (5% Cs)
0.31 (76% Ce)
2.99 (98% Pr)
...
K
0.428 (30% Ba)
0.463 (11% Ba)
0.601 (18% Ba)
0.636 (12% Ba)
0.662 (89% Ba)
0.080 (2% Ce)
0.134 (11% Ce)
0.695 (1.5% Pr)
1.487 (0.3% Pr)
2.186 (0.7%)
0.145 (2%)
0.039 (0.007%)
0.052 (0.020%)
0.129 (0.005%)
0.375 (0.0012%)
0.0264 (2.5%
Am)
0.0595 (36%
Am)
' Source: Lederer and Shirley (1978) and NCRP (1976).
" Half-life given in minutes (m), hours (h), days (d), or years (y).
'" Intensities refer to percentage of disintegrations of the nuclide itself.
t "NE" = Nuclear explosions; "NF" = Nuclear facilities; "SNAP" = SNAP-9a (System for Nuclear Auxiliary Power) which
was a satellite which dispersed 1 kg of Pu-238 in the earth's atmosphere when it burned up upon re-entry; and "FF" =
Fossil fuel power plants and other industries.
60
-------
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ater Reactors (BWRs
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61
-------
References
Be73
Ch86
C166
C176
Er65
Fa77
Ko62
Le78
Lo64
Mi71
NCRP75
NCRP76
NCRP79
NCRP87a
Bennett, E.G., "Environmental Tritium and the Dose to Man," page 1047 in Proceedings of the
Third International Congress of the International Radiation Protection Association. Washington
D.C., CONF-730907-P2, September, 1973.
Chen, J.H., Edwards, R.L., and Wasserburg, G.J., **U, ^U, and 232Th in Sea Water," Earth
Planet Sci. Lett., 80, 241, 1986.
Clark, S.P., Jr., Petennan, Z.E., and Heiir, K.S., "Abundances of Uranium, Thorium, and
Potassium," page 521 in Handbook of Physical Constants. Revised Edition, Clark, S.P., Jr., Ed.,
Geological Soc. America Memoir 97, Geological Soc. America Inc., New York, 1966.
Clanet, F., Leclercq, J., Remy, M.L., and Moroni, J. P., "Mise en evidence experimentale du
role de 1'absorption differentielle du thorium et de I'uranium sur les roches silicatees dans Petal
d'equilibre entre les activites des radioisotopes ^U et ^U dans la nature," Comptes Rendus,
Paris, D282:807, 1976.
Eriksson, E., "The Account of the Major Pulses of Tritium and Their Effects in the Atmosphere,"
Tellus, 17, 118, 1965.
Farmer, B.M., Styron, C.E., Philips, C.A., et al., "The Assessment of the Radiological Impact
of Western Coal Utilization: Phase 1," Monsanto Research Corporation, Mound Laboratory
report, 1977.
Koczy, F.E. and Rosholt, J.N., "Radioactivity in Oceanography," Nuclear Radiation in
Geophysics, Israel, H. and Krebs, A., Eds., Academic Press, New York, pg. 18, 1962.
Lederer, C.M. and Shirley, V.S. (Eds.), Table of Isotopes. 7th Ed., John Wiley & Sons, Inc.,
New York, 1978.
Lowder, W.M., Condon, W.J., and Beck, H.L., "Field Spectrometric Investigations of
Environmental Radiation in the U.S. A.," page 597 in The Natural Radiation Environment. Adams,
J.A.S. and Lowder, W.M., Eds., University of Chicago Press, Chicago, Illinois, 1964.
Miskel, J.A., "Production of Tritium by Nuclear Weapons," page 79 in Tritium. Moghissi, A. A.
and Carter, M.W., Eds., Messenger Graphics, Phoenix, Arizona, 1971.
National Council on Radiation.Protection and Measurements, "Natural Background Radiation in
the United States," NCRP Report No. 45, National Council on Radiation Protection and
Measurements, Bethesda, Maryland, November 15, 1975.
National Council on Radiation Protection and Measurements, "Environmental Radiation
Measurements," NCRP Report No. 50, National Council on Radiation Protection and
Measurements, Bethesda, Maryland, December 27, 1976.
National Council on Radiation Protection and Measurements, "Tritium in the Environment,"
NCRP Report No. 62, National Council on Radiation Protection and Measurements, Bethesda,
Maryland, March 9, 1979.
National Council on Radiation Protection and Measurements, "Public Radiation Exposure from
Nuclear Power Generation in the United States," NCRP Report No. 92, National Council on
Radiation Protection and Measurements, Bethesda, Maryland, 1987.
63
-------
NCRP87B National Council on Radiation Protection and Measurements, "Exposure of the Population in the
United States and Canada from Natural Background Radiation," NCRP Report No. 94, National
Council on Radiation Protection and Measurements, Bethesda, Maryland, December 30, 1987.
Oa72 Oakley, D.T., "Natural Radiation Exposure in the United States," U.S. EPA Office of Radiation
Programs Report ORP/SID-72-1, 1972.
Ro59 Rosholt, J.N., Jr., "Natural Radioactive Disequilibrium of the Uranium Series," U.S. Geol.
Survey Bull. 1084-A, Government Printing Office, Washington, D.C., 1959.
Ro64 Rona, E., "Geochronology of Marine and Fluvial Sediments," Science, 77, 987, 1964.
Ro66 Rosholt, J.N., Doe, B.R., and Tatsumoto, M., "Evolution of the Isotopic Composition of
Uranium and Thorium in Soil Profiles," Geol. Soc. Am. Bull., 77, 987, 1966.
Sh84 Shleien, B. and Terpilak, M.S. (Eds.), The Health Physics and Radiological Health Handbook.
7th Printing, Nucleon Lectern Associates, Inc.,Olney, MD, 1987.
Sm69 Smith, R.F., and Jackson, J.M., "Variations in the U-234 Concentration of Natural Uranium,"
Union Carbide Corp. Nuclear Division, Paducah Gaseous Diffusion Plant, Report KY-851, 1969.
St80 Styron, C.E., "An Assessment of Natural Radionuclides in the Coal Fuel Cycle," pg. 1511-1520
in: Natural Radiation Environment III. CONF-780422 (Vol.2), 1980.
Sw76 Swanson, V.E., Medlin, J.H., Hatch, J.R., et al., "Collection, Analysis, and Evaluation of Coal
Samples in 1975," U.S. Department of Interior, Geological Survey Report 76-468, 1976.
Ta64 Taylor, S.R., "Abundance of Chemical Elements in the Continental Crust: A New Table,"
Geochim. Cosmochim. Acta, 28,1273, 1964.
Ta85 Taylor, S.R. and McLennan, S.M., "The Continental Crust: Its Composition and Evolution,"
Oxford, Blackwell, 1985.
Te67 Teagarden, B.J., "Cosmic-ray Production of Deuterium and Tritium in the Earth's Atmosphere'"
J. Geophys. Res., 72, 4863, 1967.
Ti88 Tichler, J., Norden, K., and Congemi, J., "Radioactive Materials Released from Nuclear Power
Plants: Annual Report 1985," NUREG/CR-2907, BNL-NUREG-51581, Volume 6, January 1988.
UN72 United Nations Scientific Committee on the Effects of Atomic Radiation, "Ionizing Radiation:
Levels and Effects," Report to the General Assembly, with annexes, United Nations, New York,
1972.
UN82 United Nations Scientific Committee on the Effects of Atomic Radiation, "Ionizing Radiation:
Sources and Biological Effects," Report to the General Assembly, with annexes, United Nations,
New York, 1982.
64
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APPENDIX III
EPA Radiation Program Staff
Tom D'Avanzo
Radiation Program Manager, Region 1
U.S. Environmental Protection Agency
John F. Kennedy Federal Building
Room 2311
Boston, MA 02203
Paul A. Giardina
Radiation Program Manager, Region 2
U.S. Environmental Protection Agency
Room 1005 (AWM-RAD)
26 Federal Plaza
New York, NY 10278
Lewis Felleisen
Radiation Program Manager, Region 3
Special Program Section (3AM12)
U.S. Environmental Protection Agency
841 Chestnut Street
Philadelphia, PA 19107
Chuck Wakamo
Radiation Program Manager, Region 4
U.S. Environmental Protection Agency
345 Courtland Street, NE
Atlanta, GA 30365
Gary V. Gulezian
Radiation Program Manager, Region 5
(5AR26)
U.S. Environmental Protection Agency
230 S. Dearborn Street
Chicago, IL 60604
Donna Ascenzi
Radiation Program Manager, Region 6
U.S. Environmental Protection Agency
Air Enforcement Branch (6T-E)
Air, Pesticides and Toxics Division
1445 Ross Avenue
Dallas, TX 75202-2733
Gale Wright
Radiation Program Manager, Region 7
U.S. Environmental Protection Agency
726 Minnesota Avenue
Kansas City, KS 66101
FTS: 835-4502
COMM: (617) 565-4502
FTS: 264-4110
COMM: (212) 264-4110
FTS: 597-8326
COMM: (215) 597-8326
FTS: 257-3907
COMM: (404) 347-3907
FTS: 886-6258
COMM: (312) 353-2206
FTS: 255-7223
COMM: (214) 655-7223
FTS: 276-7600
COMM: (913) 551-7600
65
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Milton W. Lammering
Radiation Program Manager, Region 8
(8AT-RP)
U.S. Environmental Protection Agency
Suite 500
999 18th Street
Denver, CO 80202-2405
Michael S. Bandrowski
Radiation Program Manager, Region 9
(Al-1)
U.S. Environmental Protection Agency
75 Hawthorne Street
San Francisco, CA 94105
Jerry Leitch
Radiation Program Manager, Region 10
(AT-082)
U.S. Environmental Protection Agency
1200 Sixth Avenue
Seattle, WA 98101
Samuel T. Windham, Director
National Air and Radiation
Environmental Laboratory (NAREL)
Office of Radiation Programs
U.S. Environmental Protection Agency
1504 Avenue A
Montgomery, AL 36115-2601
Jed Harrison, Acting Director
Office of Radiation Programs-
Las Vegas Facility (ORP/LVF)
U.S. Environmental Protection Agency
P.O. Box 98517
Las Vegas, NV 89193-8517
Robert S. Dyer, Chief
Office of Radiation Programs - HQ
Radiation Assessment Branch
Radiation Studies Division (ANR-461)
U.S. Environmental Protection Agency
401 M Street, SW
Washington, DC 20480
FTS: 330-1709
COMM: (303) 293-1709
FTS:484-1048
COMM: (415) 744-1048
FTS: 399-7660
COMM: (206) 442-7660
FTS: 228-3400
COMM: (205) 270-3400
FTS: 545-2476
COMM: (702) 798-2476
FTS: 260-9630
COMM: (202) 260-9630
66
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Anthony B. Wolbarst, Chief FTS: 260-9630
Office of Radiation Programs - HQ COMM: (202) 260-9630
Remedial Guidance Section
Radiation Assessment Branch
Radiation Studies Division (ANR-461)
U.S. Environmental Protection Agency
401 M Street, SW
Washington, DC 20480
67
-------
References
Altshuler, 1963. LLD calculations.
American National Standards Institute (ANSI). 1986. Quality Assurance ProgramRequirementsfor Nuclear Facilities.
Report No. ANSI/ASME NQA-1.
Bernabee, R., Percival, D., and Martin D. 1980. "Fractionation of Radionuclides in Liquid Samples from Nuclear Power
Facilities," Health Physics, 39, pp. 57-67.
Currie, 1968. LLD calculations.
Department of Energy (DOE). 1988. The Environmental Survey Manual. Appendix D-Part 4 (Radiochemical Analysis
Procedures). Second Edition. (DOE/EH-0053)
Environmental Protection Agency (EPA). 1986. Test Methodsfor Evaluating SolidWaste(SW846):Physical/Chemical
Methods. Third Edition. Office of Solid Waste.
Environmental Protection Agency (EPA). 1988. Federal Guidance Report No. 11.
Environmental Protection Agency (EPA). 1989. Integrated Risk Information System (IRIS) (data base). Office of
Research and Development.
Environmental Protection Agency (EPA). 1990. Health Effects Assessment Summary Tables. First and Second
Quarters FY1990. Office of Research and Development. (OERR 9200.6-303).
Environmental Protection Agency (EPA). 1991. Risk Assessment Guidance for Superfund, Volume I: Human Health
Evaluation Manual, Part A. Office of Solid Waste and Emergency Response. EPA/540/1-89/002. (OS WER Directive
9285.7-01A).
National Council on Radiation Protection and Measurements (NCRP). 1978. Instrumentation andMonitoring Methods
for Radiation Protection. NCRP Report No. 57.
Nuclear Regulatory Commission (NRC). 1979. Quality Assurance for Radiological Monitoring Programs (Normal
Operations) - Effluent Streams and the Environment. Regulatory Guide 4.15, Revision 1.
Pasternak and Harley, 1971. LLD calculations.
Schaeffer, R. L., Mendenhall, W., and Ott, L. 1979. Elementary Survey Sampling, Duxbury Press, North Scituate,
Massachusetts.
Walpole, R. E., and Meyers, R. H. 1978. Probability and Statistics for Engineers and Scientists, MacMillan, New York.
69
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Index
Absorbed dose, radiation 3
Activity 4, 8-10, 29
Air data collection
background sampling 33
sampling locations 22
Analytical methods 3, 7, 17, 24, 29
Animal studies 5
Averaging time 4
B
Background
naturally occurring 33, 34
regional 10
site specific 15, 22, 23, 29, 33
Blanks 22, 27
Body weight 4
c
Calibration 7, 15, 26, 27, 29
Carcinogenesis 5
Carcinogens 5, 8
Contract Laboratory Program 9, 26
Data qualifiers 26
Data quality objectives (DQOs) 3, 7, 24
Decay products 4, 8, 9, 17, 33
Detection limits 1, 7, 9, 26, 29
lower limit of detection (LLD) 7, 9, 10, 29,37
minimum detectable concentration
(MDC) 7, 9, 10, 29
sample quantitation limit (SQL) 9
Dose
effective dose equivalent (H) 4, 5
Dose conversion factor (DCF) 4
EPA Radiation Program Staff 1
National Air and Radiation Environmental
Laboratory (NAREL) 24
Office of Radiation Programs (ORP) 25
Exposure, radiation
assessment 3, 4, 5, 15, 17, 22, 26, 33
definition 4
external 10, 13
internal 10, 13
Exposure pathways 3, 4, 5, 17, 22, 33
Guidance for Data Useability in Risk Assessment -
Part A 1
H
Half-life 8, 9, 13, 17
Health Effects Assessment Summary Tables
(HEAST) 4
Health physicist 1, 5, 9, 10,22
Hot spot 22
Human health evaluation manual (HHEM) 4
I
Instrument detection limit (IDL) 9
Intake 3, 4
Integrated Risk Information System (IRIS) 4
Ionizing radiation 3, 5
Lower limit of detection (LLD) 7, 9,10,29
M
Minimum detectable concentration (MDC) 7, 9,10,
29
N
National Air and Radiation Environmental
Laboratory (NAREL) 24
National Institute of Standards and Technology
(NIST) 27
Nuclear Regulatory Commission (USNRC) 7, 25,
26
Office of Radiation Programs (ORP) 25
Preliminary assessment/site inspection (PA/SI) 7
Q
Quality assurance/quality control
(QA/QC) 24, 26, 27, 33
Qualifiers 26
Quality assurance project plan (QAPjP) 7
Quantitation limit 9
Radiation detection instruments 7, 8
Geiger-Muller (GM) counters 13
ionization chamber 17
scintillation detectors 13
71
-------
Radioactive decay 4,9
Radiochemist 1, 5, 8-10, 22, 25, 26
Radionuclide 1, 3-5, 8-10,12,13,17,22, 24, 33
alpha particles 3, 8, 9, 13, 17, 29
beta particles 3, 8, 9, 13, 17
neutrons 8
photons 3, 8,10
relative biological effectiveness (RBE) 3, 8,24
Remedial investigation/feasibility study (RI/FS) 1
Remedial project manager (RPM) 5, 8, 9,17
Risk assessor 1, 5, 8, 9, 12, 13, 15, 17,25-
27, 29, 33
s
Sample quantitation limit (SQL) 9
Sampling and analysis plan 3, 7, 8, 10,
13, 17, 33
Surface water data collection 24
Surveys, external radiation
mobile 4, 12, 13, 17, 22
systematic grid 7
T
Target Compound List (TCL) 9
Toxicity 3, 4, 5, 8
Trip blanks 10
72 * U.S. G.P.O.:1992-341-835:60730
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