&EPA
United States
Environmental Protection
Agency
Office of Radiation and Indoor Air
National Air and Radiation
Environmental Laboratory
EPA 402-R-12-006
September 2012
www.epa.gov/narel
Radiological Laboratory
Sample Analysis Guide for
Incident Response -
Radionuclides in Soil
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EPA 402-R-12-006
www.epa.gov/narel
September 2012
Revision 0
Radiological Laboratory Sample Analysis
Guide for Incident Response -
Radionuclides in Soil
National Air and Radiation Environmental Laboratory
Office of Radiation and Indoor Air
U.S. Environmental Protection Agency
Montgomery, AL 36115
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
This report was prepared for the National Air and Radiation Environmental Laboratory of the Office of
Radiation and Indoor Air, United States Environmental Protection Agency. It was prepared by
Environmental Management Support, Inc., of Silver Spring, Maryland, under contract EP-W-07-037, Work
Assignment 1-33, managed by David Carman and Daniel Askren. Mention of trade names or specific
applications does not imply endorsement or acceptance by EPA.
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
PREFACE
The need to ensure an adequate laboratory infrastructure to support response and recovery
actions following a major radiological or nuclear incident has been recognized by a number of
federal agencies. The Integrated Consortium of Laboratory Networks (ICLN), created in 2005 by
10 federal agencies,1 consists of existing and emerging laboratory networks across the Federal
Government. ICLN is designed to provide a national infrastructure with a coordinated and
operational system of laboratory networks that will provide timely, high quality, and
interpretable results for early detection and effective consequence management of acts of
terrorism and other events requiring an integrated laboratory response. It also designates
responsible federal agencies (RFAs) to provide laboratory support across response phases for
chemical, biological, and radiological agents. To meet its RFA responsibilities, the U.S.
Environmental Protection Agency (EPA) established the Environmental Response Laboratory
Network (ERLN) to address chemical, biological, and radiological threats during nationally
significant incidents (www.epa.gov/erln/). EPA is the RFA for monitoring, surveillance, and
remediation of radiological agents. EPA will share responsibility for overall incident response
with the U.S. Department of Energy (DOE).
This document is one of several initiatives by EPA's Office of Radiation and Indoor Air
designed to provide guidance to radioanalytical laboratories that will support EPA's response
and recovery actions following a radiological or nuclear incident. This guide examines the
analysis of soil samples following a radiological incident. The guidance provided in this
document for the screening, pretreatment, and analysis of soil samples should assist those
federal, state, and commercial radioanalytical laboratories that will be challenged with a large
number of such samples when responding to a radiological incident. This document discusses
three different types of events; a radiological transportation incident, a radiological dispersal
device (ROD) ("dirty bomb"), or the detonation of an improvised nuclear device (IND). These
samples will be contaminated with varying levels of radionuclides, and will represent soil
matrices of varied composition. Advance planning by national and regional response teams, as
well as by radiological laboratories, will be critical to ensure uninterrupted throughput of large
numbers of radioactive samples and the rapid turnaround and reporting of results that meet
required data quality objectives associated with the protection of human health and the
environment. EPA's responsibilities, as outlined in the National Response Framework,
Nuclear/Radiological Incident Annex, include response and recovery actions to detect and
identify radioactive substances and to coordinate federal radiological monitoring and assessment
activities.
While the recommendations in this Guide may be implemented by radiochemistry laboratories
using their standard analytical procedures, EPA has developed a suite of validated rapid methods
for selected radionuclides in soil, water, air filters, and swipes. These methods can achieve a
required relative method uncertainty of 13% at, or above, an analytical action level of 10~4 risk.
The methods also have been tested to determine the time within which a batch of samples can be
analyzed. For these radionuclides, results for a batch of samples can be provided within a
turnaround time of hours instead of the days to weeks required by some previous methods.
References to these methods are found throughout this Guide and citations are listed at the end of
this Preface and in Section IE (References). In particular, laboratories needing to analyze soils
1 Departments of Agriculture, Commerce, Defense, Energy, Health and Human Services, Homeland Security,
Interior, Justice, and State, and the U.S. Environmental Protection Agency.
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
are encouraged to consider Rapid Method for Fusion of Soil and Soil-Related Matrices Prior to
Americium, Plutonium, and Uranium Analyses; Rapid Method for Radium-226 Analyses in Soil
Incorporating the Fusion of Soil and Soil-Related Matrices; and Rapid Method for Sodium
Carbonate Fusion of Soil and Soil Related Matrices Prior to Strontium-90 Analysis (EPA 2012a)
and validate them as recommended in the Method Validation Guide for Radiological
Laboratories Participating in Incident Response Activities (EPA 2009a).
Detailed guidance on recommended radioanalytical practices can be found in the Multi-Agency
Radiological Laboratory Analytical Protocols Manual (MARLAP), which provides detailed
radioanalytical guidance for project planners, managers, and radioanalytical personnel based on
project-specific requirements (www.epa.gov/radiation/marlap/links.html). Familiarity with
Chapters 2 and 3 of MARLAP will be of significant benefit to users of this guide. This document
is one in a planned series designed to present radioanalytical laboratory personnel, Incident
Commanders (and their designees), and other field response personnel with key laboratory
operational considerations and likely radioanalytical requirements, decision paths, and default
data quality and measurement quality objectives for analysis of samples taken after a radiological
or nuclear incident. Documents currently completed or in preparation include:
• Radiological Laboratory Sample Analysis Guide for Incidents of National Significance -
Radionuclides in Water (EPA 402-R-07-007, January 2008)
• Radiological Laboratory Sample Analysis Guide for Incidents of National Significance -
Radionuclides in Air (EPA 402-R-09-007, June 2009)
• Radiological Laboratory Sample Screening Analysis Guide for Incidents of National
Significance (EPA 402-R-09-008, June 2009)
• Method Validation Guide for Qualifying Methods Used by Radiological Laboratories
Participating in Incident Response Activities (EPA 402-R-09-006, June 2009)
• Guide for Laboratories - Identification, Preparation, and Implementation of Core
Operations for Radiological or Nuclear Incident Response (EPA 402-R-10-002, June 2010)
• A Performance-Based Approach to the Use of Swipe Samples in Response to a Radiological
or Nuclear Incident (EPA 600-R-l 1-122, October 2011)
• Guide for Radiological Laboratories for the Control of Radioactive Contamination and
Radiation Exposure (EPA 402-R-12-005, August 2012)
• Uses of Field and Laboratory Measurements During a Radiological or Nuclear Incident
(EPA 402-R-12-007, August 2012)
Comments on this document, or suggestions for future editions, should be addressed to:
Dr. John Griggs
U.S. Environmental Protection Agency
Office of Radiation and Indoor Air
National Air and Radiation Environmental Laboratory
540 South Morris Avenue
Montgomery, AL 36115-2601
(334)270-3450
Griggs.John@epa.gov
All the documents in this series are available at www.epa.gov/erln/radiation.html and at
www.epa. gov/narel/incident guides.html.
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
ACKNOWLEDGEMENTS
This guide was developed by the National Air and Radiation Environmental Laboratory
(NAREL) of EPA's Office of Radiation and Indoor Air (ORIA). Dr. John Griggs was the project
lead for this document. Special acknowledgment and appreciation are extended to Dr. Keith
McCroan, ORIA/NAREL, and Dr. Lowell Ralston and Mr. Edward Tupin, CHP, both of
ORIA/Radiation Protection Division, for their assistance in developing the protective action
guides (PAGs) used in this study. Several individuals provided valuable support and input to this
document throughout its development. We wish to acknowledge the external peer reviews
conducted by Cecelia DiPrete and Scott C. Moreland.
Numerous other individuals within EPA provided peer review of this document, and their
suggestions contributed greatly to the quality and consistency of the final document. Technical
support was provided by Environmental Management Support, Inc.
Dedication
This report is dedicated to the memory of our friend and colleague, David Garman. Dave
administered nearly three dozen separate contracted radiochemistry projects for EPA dating back
nearly 17 years, beginning with the Multi-Agency Radiological Laboratory Analytical Protocols
(MARLAP) in 1994. Dave put up with countless changes of prime contractors, priorities,
subcontractors, and budgets, all with good cheer, diligence, and all while keeping up with his
"day job" as counting room lead for alpha-spectrometry analysis at NAREL.
Dave started with EPA's National Air and Radiation Laboratory in 1992. He left many friends
throughout EPA and the radioanalytical community, and he will be greatly missed.
in
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Contents
Preface i
Acknowledgements iii
Acronyms and Abbreviations viii
Radiometric Unit Conversions x
I. Background 1
A. Structure of the Document 2
B. Goals 3
C. Radiological Scenarios 4
D. Analytical Response Time 6
E. References 6
II. Radionuclides 9
III. Discussion 11
Scenario Types 11
Specific Soil Sampling Protocols 13
Importance of Sample Radiological Screening and Particle Size Distribution 14
Laboratory Preparation of Samples 16
IV. Radioanalytical Scenario 1 (Identifying Samples With Highest Activities) 20
V. Radioanalytical Scenario 2 (Identifying Uncontaminated Soil Distant From the RDD Site or
Following Initial Remediation) 34
VI. Radioanalytical Scenario 3 (Identifying Soil Contaminated with Fission Products Following
anIND Incident) 44
Additional Points for Scenario 3 51
Appendix I. Tables of Radioanalytical Parameters for Radionuclides of Concern 56
Appendix II. Example of High Radionuclide Concentration in Soil (Radioanalytical Scenario 1:
Hijacked Resin Shipment Dispersed by Ignition) 72
Description 72
Event Sequence 72
Analysis Paths 73
Appendix III. Example of Soils Analyzed to Assess the Extent of Contamination
(Radioanalytical Scenario Example 2: Soil Analysis in the Recovery Phase Following an
RDD) 80
Description 80
Event Sequence 80
Analysis Paths 80
Appendix IV. Example of Soils Analyzed Following an IND Incident (Radioanalytical
Scenario Example 3) 86
Description 86
Event Sequence 86
Analysis Paths 86
Appendix V. Representative Analytical Processing Times 92
Appendix VI. Establishing DQOs and MQOs for Incident Response Analysis 93
Appendix VII. Net Count Rate and Counting Times for Typical Nuclear Instrumentation Used
for Rapid Analyses (Example) - 10^ and lO^Risk 101
IV
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Figures
Figure 1 - Autoradiograph of Particles from Palomares Incident 14
Figure 2 - Initial Screening and Pretreatment Process 17
Figure 3 - Radioanalytical Scenario 1 (Identifying Samples with Highest Activities) 20
Figure 4 - Radioanalytical Scenario 2 (Identifying Samples with Activities less than 10^ Risk -
First Year) 34
Figure 5 -Radioanalytical Scenario 3 (Samples Resulting from an IND) 44
Figure 6 - Timeline for IND Parent-Progeny Activity Determinations 52
Figure 7 - Analytical Processing Timeline for Soil Sample Following an IND 92
Figure 8 -Decision Symbol Used in Flow Diagrams 93
Figure 9 - The Data Quality Objective Process 94
Figure 10 - Example Illustrating Case (a) Baseline Condition (null hypothesis): Parameter
Exceeds the AAL 97
Figure 11 - Example Illustrating Case (b) Baseline Condition (null hypothesis): Parameter does
not Exceed the AAL 97
Tables
Table 1 -Possible Radionuclides Resulting from an RDD 9
Table 2 -Radionuclides Resulting from a Fission Event 10
Table 3 - Radionuclides with Low-Abundance Gamma Rays Not Usually Used for Analysis... 32
Table 4 - Beta-Only Emitters 33
Table 5 - Time for Certain Radionuclide Pairs to Achieve Maximum Progeny Activity 51
Table 6A - Analytical Action and Decision Levels (AAL and ADL) and 57
Required Method Uncertainty Corresponding to Early Phase and First Year PAGs in Soil 57
Using Gross Alpha Screening Methods 57
Table 6B - Analytical Action and Decision Levels (AAL and ADL) and 58
Required Method Uncertainty Corresponding to Early Phase and First Year PAGs for Soil 58
Using Gross Beta/Gamma Screening Methods 58
Table 6C - Analytical Action and Decision Levels (AAL and ADL) and 59
Required Method Uncertainty Corresponding to Early Phase and First Year PAGs for Soil 59
Using Radionuclide-Specific Methods for Alpha Emitters 59
Table 6D -Analytical Action and Decision Levels (AAL and ADL) and 60
Required Method Uncertainty Corresponding to Early Phase and First Year PAGs for Soil 60
Using Radionuclide-Specific Methods for Beta/Gamma Emitters 60
Table 7A - Analytical Action and Decision Levels (AAL and ADL) and Required Method
Uncertainty Corresponding to First Year Exposure at 10 4 and 10 6 Risk for Soil 61
Using Gross Alpha Screening Methods 61
Table 7B - Analytical Action and Decision Levels (AAL and ADL) and Required Method
Uncertainty Corresponding to First Year Exposure at 10~4 and 10~6 Risk for Soil 62
Using Gross Beta/Gamma Screening Methods 62
Table 7C - Analytical Action and Decision Levels (AAL and ADL) and Required Method
Uncertainty Corresponding to First Year Exposure at 10~4 and 10~6 Risk for Soil 63
v
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Using Radionuclide-Specific Methods for Alpha Emitters 63
Table 7D - Analytical Action and Decision Levels (AAL and ADL) and Required Method
Uncertainty Corresponding to First Year Exposure at 1CT4 and 1CT6 Risk for Soil 64
Using Radionuclide-Specific Methods for Beta/Gamma Emitters 64
Table 8A - Analytical Action and Decision Levels (AAL and ADL) and 65
Required Method Uncertainty Corresponding to Risk Limits for 50-Year Exposure for Soil 65
Using Gross Alpha Screening Methods 65
Table 8B - Analytical Action and Decision Levels (AAL and ADL) and 66
Required Method Uncertainty Corresponding to Risk Limits for 50-Year Exposure for Soil 66
Using Gross Beta/Gamma Screening Methods 66
Table 8C - Analytical Action and Decision Levels (AAL and ADL) and 67
Required Method Uncertainty Corresponding to Risk Limits for 50-Year Exposure for Soil 67
Using Radionuclide-Specific Methods for Alpha Emitters 67
Table 8D -Analytical Action and Decision Levels (AAL and ADL) and 68
Required Method Uncertainty Corresponding to Risk Limits for 50-Year Exposure for Soil 68
Using Radionuclide-Specific Methods for Beta/Gamma Emitters 68
Table 9 -Additional Radionuclides Potentially Present in Soil 69
Immediately Following an IND 69
Table 10A - Analytical Action and Decision Levels (AAL and ADL) and Required Method
Uncertainty Corresponding to Early Phase 1,000-mrem and First Year 2,000-mrem PAG
Values for Fission Products in Soil Using Gross Beta/Gamma Screening Methods 70
Table 10B - Analytical Action and Decision Levels (AAL and ADL) and Required Method
Uncertainty Corresponding to Early Phase 1,000-mrem and First Year 2,000-mrem PAG
Values for Fission Products in Soil Using Radionuclide-Specific Methods for Beta/Gamma
Emitters 71
Table 11 -Principal Radionuclides Identified in Resins 72
Table 12 -Results of Screening Analysis for Soil Samples 73
Table 13 -Results of Screening Analysis for Soil Samples 77
Table 14 -Results of Radionuclide Specific Analysis in Soil Samples 78
Table 15 - Screening Results for Soil Samples Following an IND 81
Table 16 -Results of Gross Gamma Analysis of Soil Samples 81
Table 17 -Results of Gross Alpha and Beta Analysis of Soil Samples 83
Table 18-Results of Soil Analysis Following an ROD 84
Table 19 - Initial Gamma Dose Rate Survey in Soil Following an IND 87
Table 20 -Results for Gamma Spectrometry in Soil Samples Following an IND 88
Table 21 - Results for Gross Alpha in Soil Following an IND 89
Table 22 -Results for Isotopic Am and Pu in Soil Following an IND 89
Table 23 - Results for 90Sr and 89Sr in Soil Following an IND 90
Table 24 - Summary and Evaluation of Results for Soil Samples Following an IND 90
Table 25 - TheDQO process Applied to a Decision Point 95
Table 26 -Possible Decision Errors 95
Table 27 -The DQO Process Applied to a Decision Point 96
Table 28 -Values ofzy a (or z^J for Some Commonly Used Values of a or/? 97
Table 29 - DQOs and MQOs for Radioanalytical Scenario 1. Laboratory Prioritization Decisions
Based on Screening (Gross a, P, or y) and Radionuclide-Specific Measurements 99
VI
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Table 30 - DQOs and MQOs for Scenario 2. Laboratory Prioritization Decisions Based on
Screening (Gross a, P, ory and Radionuclide-Specific Measurements) 99
Table 31 - DQOs and MQOs for Radioanalytical Scenario 3. Laboratory Prioritization Decisions
Based on Screening (Gross a, P, or y) and Radionuclide Specific Measurements 100
Table 32 - Net Count Rate and Counting Times for Typical Nuclear Instrumentation Used for
Rapid Analyses (Example) - 10^ and lO^Risk 101
vn
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
ACRONYMS AND ABBREVIATIONS
(Excluding chemical symbols and formulas)
a alpha particle
a probability of Type I decision error
AAL analytical action level
ADL analytical decision level
AL action level
P beta particle
ft probability of Type II decision error
Bq becquerel (1 dps)
CFR Code of Federal Regulations
Ci curie
cm centimeter
cpm counts per minute
d day
DL discrimination limit
DOE United States Department of Energy
DP decay product(s)
dpm disintegration per minute
dps disintegration per second
DQO data quality obj ective
DRL derived response levels
DRP discrete radioactive particle
Epmax maximum energy of the beta-particle emission
EDX energy di spersive X-ray analysi s
ERLN Environmental Response Laboratory Network
EPA United States Environmental Protection Agency
FRMAC Federal Radiological Monitoring and Assessment Center
y gamma radiation
g gram
Ge germanium semiconductor
GM Geiger-Mueller (detector)
GPC gas proportional counting
GS gamma spectrometry
Gy gray
h hour
HO null hypothesis
HI alternate hypothesis
HF hydrofluoric acid
HIC high integrity container
HPGe high-purity germanium [detector]
1C incident commander
ICLN Integrated Consortium of Laboratory Networks
IND improvised nuclear device (i.e., a nuclear bomb)
in inch
kg kilogram (103 gram)
Vlll
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
keV thousand electron volts (103eV)
L liter
LEPD 1 ow-energy photon detector
LSC liquid scintillation counter/counting
MARLAP Multi-Agency Radiological Laboratory Analytical Protocols Manual
MARS SIM Multi-Agency Radiation Survey and Site Investigation Manual
mCi millicurie (1(T3 Ci)
MeV million electron volts (106 eV)
mg milligram (1CT3 g)
mL milliliter (1(T3 L)
mrem millirem (1CT3 rem)
uCi microcurie (1CT6 curie)
ug microgram (1CT6 g)
MDC minimum detectable concentration
Micro-XANES ..micrometer-scale X-ray absorption near edge structure spectroscopy
Micro-XRF micrometer-scale X-ray fluorescence
min minute
MQO measurement quality obj ective
Nal(Tl) thallium-activated sodium iodide detector
NAREL EPA National Air and Radiation Environmental Laboratory
NORM naturally occurring radioactive materials
ORIA EPA Office of Radiation and Indoor Air
relative required method uncertainty
protective action guide
pCi picocurie (1(T12 Ci)
PM project manager
QA quality assurance
QC quality control
rad radiation absorbed dose
RDD radiological dispersal device (i.e., "dirty bomb")
RFA responsible federal agency
rem roentgen equivalent: man
RTG radioisotope thermoelectric generator
s second
SI International System of Units
SOF sum of fractions
SOP standard operating procedure
SR synchrotron radiation
Sv sievert
tu half-life
TEDE total effective radiation dose equivalent
TRU transuranic elements
tSIE transformed spectral index of the external standard
u required method uncertainty
y year
z z 1-cc and \—B quantiles of the standard normal distribution function
l-a' I-P ^ M
IX
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
RADIOMETRIC UNIT CONVERSIONS
To Convert
years (y)
disintegrations per
second (dps)
Bq
Bq/kg
microcuries per
milliliter ((iCi/mL)
disintegrations per
minute (dpm)
cubic feet (ft3)
gallons (gal)
gray (Gy)
roentgen equivalent
man (rem)
To
seconds (s)
minutes (min)
hours (h)
days (d)
becquerels (Bq)
picocuries (pCi)
pCi/g
pCi/L
jiCi
pCi
cubic meters (m3)
liters (L)
rad
sievert (Sv)
Multiply by
3.16xl07
5.26xl05
8.77xl03
3.65xl02
1
27.0
2.70xl(T2
109
4.50xl(T7
4.50XKT1
2.83xlO~2
3.78
102
io-2
To Convert
s
min
h
d
Bq
pCi
pCi/g
pCi/L
pCi
jiCi
m3
L
rad
Sv
To
y
dps
Bq
Bq/kg
(iCi/mL
dpm
ft3
gal
Gy
rem
Multiply by
3.17xl(T8
1.90xl(T6
1.14x10^
2.74xlO~3
1
3.70xlO~2
37.0
io-9
2.22
2.22xl06
35.3
0.264
io-2
IO2
NOTE: Traditional units are used throughout this document instead of International System of
Units (SI) units. PAGs and their derived concentrations appear in official documents in the
traditional units and are in common usage. Conversion to SI units will be aided by the unit
conversions in this table.
x
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
I. BACKGROUND
This guide deals with the analysis of soil3 samples that may have been contaminated as the result
of the deployment of a radiological dispersion device (RDD) or improvised nuclear device
(IND), or a radiological materials transportation event, accident at a nuclear facility, or an
intentional release of radioactive materials onto surface soil. In the event of a major incident that
releases radioactive materials to the environment, EPA may need to turn to qualified commercial
radioanalytical laboratories to support national response teams in determining the radionuclide
source term(s), extent and magnitude of contamination, and the possible actions to be taken
based on the potential human radiation doses compared to national guidelines. In order to
expedite sample analyses and data delivery to the client, the laboratories will need guidance on
EPA's expectations.
An incident response to a release of radioactivity to the environment likely will occur in three
phases: "early", "intermediate", and "recovery." Each phase of an incident response will require
different and distinct radioanalytical resources to address the different consequences, manage-
ment, priorities, and requirements of each phase. Some of the more important radioanalytical
laboratory resources germane to an incident response consist of radionuclide identification and
quantification capability, sample load capacity, sample processing turnaround time, quality of
analytical data, and data transfer capability.
The exposure to individuals from soils is assessed in a different manner than either air or water
exposure pathways. Exposure from soil is based on both direct radiation (i.e., "ground shine")
and inhalation due to resuspension of the contaminated soil. Both of these mechanisms are
affected by weathering of the soil. This combination yields slightly different protective action
guides (PAGs) concepts than for air and water. Part of this difference is that decay and
weathering are taken into account when calculating doses based on the soil concentration. For
soils, the early phase begins at the initial event and lasts for approximately 96 hours. The PAG is
1,000 mrem during this phase. Because this aspect of the event is so short-lived laboratories that
do become involved with soil sample analysis will need to respond promptly with analytical
values for samples that are conservative4 in their assessment of the concentration.
Once the early phase has concluded and soil analyses are in progress, the specific action levels
are still dose or risk based but the time period of exposure based on weathering is used to
establish specific dose- or risk-based concentrations.
During the intermediate phase the source term radionuclides will have been qualitatively
identified, however radionuclide concentrations and the extent of the contaminated zone still
may not be well defined. The radioanalytical resources that are needed will depend on the PAGs
that are implemented for the incident by the project team. These PAGs may depend upon
3 For purposes of this document, "soil" refers to loose, unconsolidated material consisting of sand, silt, and clay
mineral particles together with organic matter of various types, which has been subjected to weathering and
biological processes, without regard to morphology, moisture content, particle size, or mode of origin.
4 In this discussion the term "conservative" refers to measurement results where the acceptable error rate for risk of
deciding that analyte is not present at the action level when it is indeed present at or above the action level, is very
low (e.g., < 0.05). See Appendix VI for details.
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
location and habitation. For the intermediate phase, PAGs have been established to limit the
projected exposures for different periods not to exceed:
• 1,000-mrem total effective radiation dose equivalent (TEDE) over the first few days,
• 2,000-mrem TEDE over the first year,
• 500-mrem TEDE during the second year, or
• 5,000-mrem over the next 50 years (including the first and second years of the incident).
In addition, radionuclide concentration limits for food, water, and air as regulated by the Food
and Drug Administration and EPA would be applicable. For the analysis of soils the PAG values
are in units of pCi/g of soil to correspond to these doses.
The final, or "recovery," phase occurs as part of a radiological incident site remediation effort.
The PAG that may be applicable for this recovery phase has as a limit of 5,000 mrem over the
next 50 years (including the first and second years of the incident response). Risk-based
exposure limits for each of these time periods also have been established, and in turn converted
into equivalent soil concentrations. This document also addresses concentrations of radionuclides
in soils at the 10~4 and 10"6 risk factors. During this final phase, when site characterization and
remediation cleanup effectiveness is determined, there is a potential need for more extensive
radiochemical analyses at these lowest levels of detection.
During all phases of an incident response, radioanalytical resources are needed for identifying
the radionuclide source term(s), quantifying the radionuclides in soils, and screening the gross
radiation of samples for prioritization of sample processing or for information related to the
general level of contamination. This guide has been developed to provide the incident responder
(Project Manager, On Scene Coordinator, Incident Commander) and the laboratories used during
an incident with a logical processing scheme to prioritize sample processing in relation to the
radionuclide concentration action levels corresponding to established PAGs.
A. Structure of the Document
Background (this section). This section describes the radiological event phases, goals of this
document, the scenarios that may be encountered during a radiological event, and the sampling
issues that may ensue long after the event has terminated.
Discussion. This section provides a perspective on the types of concerns that will arise when
dealing with soil samples resulting from a radiological event. Effects of particle non-
homogeneity, weathering, oxidation state, and the buildup of radioactive progeny are discussed
as background material for potential radionuclide scenarios. The scenarios are based on historical
events that are similar to potential future events. Additionally, specific information regarding the
type of screening instrumentation and potential background interferences that will be present is
discussed. This material should be considered for inclusion when writing standard operating
procedures for laboratory analysis.
Scenarios. There are three different situations described in this document. These are:
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
• The first scenario assumes unknown radionuclides and elevated unknown
concentrations in soil samples. Sample priority flow path is determined using
methods based on identifying gross radionuclide activity concentrations that exceed a
PAG during the early to intermediate phase of an event.
• The second scenario deals with samples that are being used to determine the extent of
contamination of identified radionuclides dispersed on the surface of specific soils
over a wide area. The immediate need is to identify those samples taken from areas
with concentrations below a designated action level (e.g., less than l(T4risk).
• The third scenario assumes that an event has occurred where fresh fission products
have been released. Such an event could be the result of a containment breach at a
nuclear power facility or from a terrorist cell detonating an improvised nuclear
device. The analytical support from the laboratory will be focused on identifying and
quantifying gamma-ray emitting radionuclides and on principal alpha and beta
emitters.
These scenarios may be applicable in different phases of the event, although usually the
associations are: Scenario 1 - early phase, Scenario 2 - intermediate phase, and Scenario 3 - the
result of a mixed fission product event that may span a long time period well after the recovery
phase. The first two scenarios deal with events that would involve single or multiple
radionuclides that result from individual or unrelated sources. In the third scenario, the
radionuclides to be determined are intermediate- and long-lived fission and activation products
that will be present with short-lived fission products. This represents a specific closed set of
potential radionuclides, most of which will be determined via gamma ray spectrometry. Some of
the radionuclides not determined by gamma-ray spectrometry initially will be 90Sr, 234>235>238u,
and 239 + 240Pu, while radionuclides such as 99Tc, 129I, and 135Cs will be examined under long-term
surveillance. Other radionuclides are also possible and likely will be investigated, but those cited
here probably have the greatest significance to dose.
Examples. Each of the scenarios will be addressed with a specific example that includes
analytical values for the samples so that the reader will be able to see how the flow charts may be
implemented. Each example also will provide a timeline for the laboratory processes so that the
response times can be put into the perspective of the incident.
B. Goals
The ultimate purpose of the overall process described in this guide is to ensure that public health
is protected. The recommendations in this guide are based upon PAGs for the early phase and
first year of exposure, or 10 4 to 10 6 cancer risks for longer term exposure to each of the listed
radionuclides. Sampling of soil to a specified depth and over a certain area needs to be integrated
into the project data quality objectives (DQOs) as these concentrations of soil are used to
calculate the dose/risk-based corresponding soil concentrations. The depth and areal distribution
form the basis of the models for resuspension/inhalation and direct radiation exposure found in
Tables 6 to 9. The specific methods and assumptions used in these models are cited in the
Federal Radiological Monitoring and Assessment Center (FRMAC) Assessment Manual,
Volume 1 (FRMAC 2010). The incident commander (or his designee) will need to specify what
the depth of sample is for the incident.
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
This document does not address long-term distribution and migration of radionuclides from the
surface of the soil due to weathering over a long period of time. The sampling regime required
for soil penetration beyond the surface will likely be an event-specific measurement quality
objective that is based on the type of soil, the specific climate of the area, and the type of
radionuclide under investigation.
C. Radiological Scenarios
The response to radiological events can be subdivided into three phases: early (onset of the event
to about day 4), intermediate (about day 4 to about day 30), and recovery (beyond about day 30).
This guide concentrates on the time from the end of the early phase, through the intermediate and
recovery phases. During the early phase, analytical priorities need to address the protection of the
public and field personnel due to potentially high levels of radioactivity. During the intermediate
phase, the radionuclides and matrices of concern have been identified, and the quantitative levels
suitable for making decisions based on action levels need to be rapidly determined. Laboratories
performing analyses must focus on rapid turnaround of sample results and optimized sample
analysis so that rapid determination can be made of whether or not PAGs have been exceeded.
During the recovery phase, the screening techniques used for sample prioritization may be less
effective because activity concentration will begin to approach background. The focus here will
be on the latter portions of the flow charts, which entail the specific radionuclide analyses and a
prioritization of samples for processing.
Three distinct radioanalytical scenarios and associated flow charts are presented for soil
potentially contaminated with radionuclides. The first two assume that the radioactive material is
unknown.
• In the first scenario, samples are being taken close-in to where the event occurred. The soil
will be highly contaminated with an unknown quantity of yet unidentified radionuclides. The
first priority is to determine how the health and safety of the public and emergency workers
may be affected by the level of contamination.
• The second scenario deals with samples that are taken either later in the event or further from
the initial event site. The laboratory analyses of these samples help to determine the extent of
areal contamination of the identified radionuclides.
• The third scenario examines the sampling issues that may arise following an event where
fresh fission products have been released from a power plant containment breach or an
improvised nuclear device (IND). The major screening technique in this event will be gamma
spectrometry because so many of the fission products are gamma emitters. This scenario
poses a much different challenge from the previous two not only because of the number of
radionuclides that result from such an event, both short- and long-lived, but also because of
the radionuclides' wide range of chemical reactivity in the environment.
The priority in the first radioanalytical scenario is to identify all the radionuclides present near
the incident center and their estimated concentrations in the soils sampled as compared to the
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
PAGs. This is most likely to occur in the early phase. The need to identify the extent of the
spread of contamination (Radioanalytical Scenario 2) most likely will occur in the intermediate
phase and into the recovery phase. Once the radionuclides are identified, the modified flow chart
(Radioanalytical Scenario 2) for either the intermediate or recovery phase may be used
depending upon the direction from the incident commander or on-scene coordinator.
Radioanalytical Scenario 3 deals with the processing of samples following an IND or nuclear
power plant incident. Here, the most effective preliminary screening will be performed using
gamma spectrometry analysis. The flow chart in Scenario 3 may be used from the early through
the recovery phase. Although there are specific fission products that are not gamma ray emitters
(90Sr, 99Tc, etc.), this flow chart provides a good general approach to sample prioritization as
both classes of radionuclides will appear in samples.
The attached charts and accompanying numbered notes and data tables depict the anticipated
analytical flow required to respond rapidly and consistently. In keeping with concepts of the
Multi-Agency Radiation Laboratory Analytical Protocols Manual (MARLAP 2004), this guide
does not prescribe the use of specific analytical methods. A performance-based approach for the
selection of appropriate analytical methods by the laboratory will be used to achieve
measurement quality objectives (MQOs) specified by this document and incident responders.
MQOs are statements of performance objectives or requirements for selected method
performance characteristics. Method performance characteristics include the method's:
• uncertainty;
• detection capability;
• quantification capability;
• applicable concentration range;
• specificity; and
• ruggedness.
An example MQO for the method uncertainty at a specified concentration, such as the action
level, might be:
"For radionuclide specific analysis of 241Am, a required method uncertainty (at la) of 8.2
pCi/g or less is required at the 10~4 risk level (first year exposure) action level of 65 pCi/g."5
The MQOs and any other analytical requirements serve as the basis for the laboratory's selection
of a method under a performance-based approach. The laboratory should have performance data
to demonstrate the method's ability to achieve the project-specific MQOs.
The scenarios presented in this document are examples of how to establish MQOs based on the
tables of soil equivalent concentration values for different PAGs. MQOs specific to an event will
be developed by the incident command and project personnel to address a particular event.
However, in order to have an analytical approach in place to address a variety of incident
5 This assumes a tolerable error rate for Type I and II errors of 1% and 5%, respectively and a discrimination level of
32.5 pCi/g.
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
scenarios, the identified decision points in the accompanying flow diagrams provide some
specified MQOs — primarily in the form of required method uncertainties — for analyzing the
radionuclides of concern. For example, at most of the decision points in the diagrams where a
quantitative value is needed for a radionuclide specific analysis, a required method uncertainty of
13 percent of the action level is used. In a few cases, an MQO in the form of a required detection
limit is used. Once the appropriate method has been selected, then based on the required method
uncertainty or detection limit, the laboratory can select the proper aliquant size, counting time
and other parameters to meet the MQOs in the most efficient manner.
D. Analytical Response Time
Decisions regarding the extent of contamination in surface soils will need to be made in a timely
manner. Approximate times required for laboratory processing of these samples and finalizing
the sample results are shown in Appendix IV. This identifies the workflow for making
qualitative and quantitative measurements of high-activity concentration contaminated soil
samples (Radioanalytical Scenario 1). In addition, results of the sample radioanalytical
measurements need to be communicated promptly by the laboratory to the project manager (PM)
so that decisions regarding movement of population, sheltering, and additional sampling can be
made.
E. References
U.S. Environmental Protection Agency (EPA). 1992. Manual of Protective Action Guides and
Protective Actions for Nuclear Incidents. Washington, DC. EPA 400-R-92-001, May.
Available at: http://www.epa.gov/rpdwebOO/rert/pags.html.
U.S. Environmental Protection Agency (EPA). 1999. Cancer Risk Coefficients for
Environmental Exposure to Radionuclides. Federal Guidance Report No. 13. EPA 402-R-99-
001, September. Available at: www.epa.gov/radiation/assessment/pubs.html.
U.S. Environmental Protection Agency (EPA). 2000. Multi-Agency Radiation Survey and Site
Investigation Manual (MARSSIM), Revision 1. 2000. NUREG-1575 Rev 1, EPA 402-R-97-
016 Revl, DOE/EH-0624 Revl. August. Available from www.epa.gov/radiation/marssim/.
U.S. Environmental Protection Agency (EPA). 2002. Final Implementation Guidance for Radio-
nuclides, EPA 816-F-00-002. 40 CFR 141.26(a)(2)(iii). Available at:
water.epa.gov/lawsregs/rulesregs/sdwa/radionuclides/upload/2009 04 16 radionuclides gui
de_radionuclides_stateimplementation.pdf
U.S. Environmental Protection Agency (EPA). 2004. Response Protocol Toolbox: Planning for
and Responding to Drinking Water Contamination Threats and Incidents. Interim Final,
December. Office of Water. EPA 817-D-03-001 through EPA 817-D-03-007. Available at:
www.epa.gov/watersecuri ty/pubs/rptb_response_guidelines.pdf
U.S. Environmental Protection Agency (EPA). 2008. Radiological Laboratory Sample Analysis
Guide for Incidents of National Significance - Radionuclides in Water. Revision 0. Office of
Air and Radiation, Washington, DC. EPA 402-R-07-007, January. Available at:
www.epa.gov/narel/incident guides.html.
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
U.S. Environmental Protection Agency (EPA). 2010a. Rapid Radiochemical Methods for
Selected Radionuclides in Water for Environmental Restoration Following Homeland
Security Events, Office of Air and Radiation, National Air and Environmental Research
Laboratory. EPA 402-R-10-001, February. Revision 0.1 issued online only October 2011.
Available at: www.epa.gov/narel/incident_guides.html and www.epa.gov/erln/radiation.html.
U.S. Environmental Protection Agency (EPA). 201 Ob. Guide for Laboratories -Identification,
Preparation, and Implementation of Core Operations for Radiological or Nuclear Incident
Response. Revision 0. Office of Air and Radiation, Washington, DC. EPA 402-R-10-002,
June. Available at: www.epa.gov/narel/incident_guides.html.
U.S. Environmental Protection Agency (EPA). 2011. A Performance-Based Approach to the Use
of Swipe Samples in Response to a Radiological or Nuclear Incident. Revision 0. Office of
Research and Development, Cincinnati, OH, and Office of Radiation and Indoor Air,
Washington, DC. EPA 600/R-l 1/122, October. Available at: http://oaspub.epa.gov/eims/
eimscomm.getfile?p_download_id=504097 and www.epa.gov/narel/incident_guides.html.
U.S. Environmental Protection Agency (EPA). 2012a. Rapid Method for Fusion of Soil and Soil-
Related Matrices Prior to Americium, Plutonium, and Uranium Analyses for Environmental
Remediation Following Homeland Security Events. Rapid Method for Radium-226 Analyses
in Soil Incorporating the Fusion of Soil and Soil-Related Matrices for Environmental
Remediation Following Homeland Security Events. Rapid Method for Sodium Carbonate
Fusion of Soil and Soil Related Matrices Prior to Strontium-90 Analysis for Environmental
Remediation Following Homeland Security Events. Revision 0, June. Office of Air and
Radiation, National Air and Radiation Environmental Laboratory, and Office of Research
and Development, National Homeland Security Research Center. Available at:
www.epa.gov/narel/incident_guides.html.
U.S. Environmental Protection Agency (EPA). 2012b. Guide for Radiological Laboratories for
the Control of Radioactive Contamination and Radiation Exposure. Revision 0. Office of Air
and Radiation, National Air and Radiation Environmental Laboratory, and Office of
Research and Development, National Homeland Security Research Center. EPA 402-R-12-
005, August. Available at: www.epa.gov/narel/incident_guides.html.
U.S. Environmental Protection Agency (EPA). 2012c. Uses of Field and Laboratory
Measurements During a Radiological or Nuclear Incident. Revision 0. Office of Air and
Radiation, Washington, DC. EPA 402-R-12-007, August. Available at:
www.epa.gov/narel/incident guides.html.
U.S. Department of Energy (DOE). (2010) The Federal Manual for Assessing Environmental
Data During a Radiological Emergency, SAND2010-1405P, FRMAC Assessment Manual,
Volume 1, Overview and Methods. Available at: www.nv.doe.gov/library/publications/
frmac/SAND2010-1405P VOLl.pdf.
U.S. Food and Drug Administration (FDA). 1998. Accidental Radioactive Contamination of
Human Food and Animal Feeds: Recommendations for State and Local Agencies. 13 August.
Available at: http://www.fda.gov/cdrh.
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
U.S. Department of Health, Education and Welfare (HEW). 1970. Radiological Health
Handbook, p. 123. National Nuclear Data Center, Brookhaven National Laboratory. Available
atwww.mcw.edu/FileLibrary/Groups/AMRSO/Files/RHHcomplete.pdf.
Multi-Agency Radiological Laboratory Analytical Protocols Manual (MARLAP). 2004. EPA
402-B-04-001A, July. Volume I, Chapters 3, 6, Volume II. Available at: www.epa.gov/
radiation/marlap.
Consensus Methods
Some recognized methods (i.e., published through a standards organization either nationally or
internationally) and some published in the refereed literature for the analysis of radionuclides in
soil, are included below. The American Society for Testing and Materials (ASTM) methods may
be purchased online from www.astm.org. However in every case the individual laboratory must
perform method validation in their own laboratory for a soils matrix to ensure that the results will
conform to the needs of the incident.
ASTM C1402-04 (2009). Standard Guide for High-Resolution Gamma-Ray Spectrometry of Soil
Samples.
Berne, A. 1997. Plutonium in Soil Residue. Environmental Measurements Laboratory, HASL-
300 (28th Edition), Method Pu-03-RC.
Krey, P.W., and D.C. Bogen. 1987. "Determination of Acid Leachable and Total Plutonium in
Large Samples," Journal of Radioanalytical and Nuclear Chemistry, 335, vol. 115.
Holgye, Z. 1991. "Determination of Plutonium in Soil." Journal of Radioanalytical and Nuclear
Chemistry, 275, 149:2.
Ohtsuka, Y. et al. 2006. "Rapid Method for the Analysis of Plutonium Isotopes in a Soil Sample
within 60 Minutes," The Japan Society for Analytical Chemistry, Analytical Sciences,
309:22.
Yamamato, Y. 1985. "Rapid Dissolution of Plutonium in Soil by Fusion with Ammonium
Hydrogen Sulfate Followed by Plutonium Determination by Ion Exchange and Alpha
Spectrometry." Journal of Radioanalytical and Nuclear Chemistry, 401, 90:2.
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
II. RADIONUCLIDES
Table 1 identifies potential radionuclides6 that could be used in a radiological dispersal device (a
"dirty bomb" or RDD), and Table 2 identifies those that would result from a release of fresh
fission products (such as a nuclear power plant breach or an IND). These radionuclides could
subsequently contaminate soils in the vicinity, and downwind of, the event.
Several of the radionuclides in these tables have progeny that also are radioactive. Thus, if 241Pu
is found, 241Am will be present.7 However the extent to which progeny may be present will
depend on the age of the material used in the RDD.
Similarly, several pairs of radionuclides are shown in Table 2. In a fission event, if the parent
(listed first) is found in a sample then the progeny also will be present. However, they may not
be in radiochemical equilibrium due to differences in the chemical reactivity in the environment
and the time elapsed since the event.
Table 1 - Possible Radionuclides Resulting from an RDD
Alpha Emitters [5]
Am-241[1J
Cm-242[1]
Cm-243[1]
Cm-244[1]
Np-237
Po-210 [4]
Pu-238 [1]
Pu-239 [1]
Pu-240 [1]
Ra-226 [1J
Th-228
Th-230
Th-232
U-234
U-235 [1]
U-238 [1]
U-Nat
Beta/Gamma Emitters
Ac-227
Bi-210 [4]
Bi-212 [4]
Bi-214 [4]
Co-57
Co-60
Cs-137
1-125
1-129
Ir- 192
p.32[2]
Pd-103
Pb-210 [4]
Pb-212 [4]
Pb-214 [4]
Pu-241 [2]
Ra-228 [2]
Se-75
Notes:
The following notes are for both Tables 1 and 2:
[1] Principally an alpha emitter with low abundance gamma rays; see Table 2.
[2] Beta only emitter (a small fraction of 241Pu also decays by alpha emission).
[3] Parent is a low abundance or non-gamma emitter; progeny used for quantification by
gamma spectrometry.
[4] These radionuclides are found in many environmental samples as a result of being decay
progeny of 226Ra or 224Ra. Care should be taken in the assignment of their half-lives in
gamma spectrometry libraries.
[5] Some alpha-emitting radioisotopes (e.g., Pu-239 and Pu-240) cannot be resolved even
through alpha spectrometric measurements. The activities for both radionuclides under
these circumstances are usually reported as one value for239 + 240Pu.
6 Radionuclides with half-lives less than about 12 hours have not been included in this list (unless they are short-
lived progeny of a long-lived progenitor) as it is unlikely that they will be deposited on soil and still detectable
shortly after the event.
7 The production of the 23^240pu isotopes results in the production of 241Pu as a result of multiple neutron capture.
Pu-241 has a 14-year half-life. If the nuclear material is "old" measurable activity of241 Am (decay product of 241Pu)
may be present, even though it was not the radionuclide originally part of the event.
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Table 2 - Radionuclides Resulting from a Fission Event
Alpha Emitters
Am-241[1]
U-234
U-235 [1]
U-238 [1]
Pu-238
Pu-239 [1]
Pu-240 [1]
Pu-241
Beta/Gamma Emitters
Ba-140/ La- 140
Ce-141
Ce-143/Pr-143
Ce-144/Pr-144
Cs-134
Cs-137 [3]
Eu-154
Mo-99/Tc-99m
Nd-147/Pm-147
Eu-155
H-3
I-131/Xe-131
1-133
Np-239
Pm-151/Sm-151
Ru-103/Rh-103
Ru-106/Rh-106 [3]
Sb-125
Sr-89 [2]
Sr-90/Y-90 [2]
Tc-99 [2]
Te-132/I-132 [3]
Zr-95/Nb-95
Zr-97/Nb-97
Activation Products
Co-58
Np-239
Ag-llOm
Co-60
Cr-51
Fe-59
Mn-54
Na-24
a. See numbered notes following Table 1.
b. This table only represents the most likely radionuclides, with half lives greater than about one day,
to be detected following a fission event.
An RDD event may not necessarily have one radionuclide; several different radionuclides and
their progeny may be present. In a fresh fission product event, activation products (such as those
listed in Table 2) also may be present dependent upon the type of material involved in the
incident.
The flow charts that accompany each scenario enable the laboratory to evaluate the activity
concentration from the specific radionuclides identified against the initial screening results to
ensure large contributors to the total activity concentration have not been missed.
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
I. DISCUSSION
Scenario Types
Appendix I contains 14 tables that identify
the analytical action levels (AAL),
analytical decision levels (ADL) and
required method uncertainty for the radio-
nuclides listed in Tables 1 and 2.
Analytical measurements are compared to
the ADL when making decisions
regarding exceeding an AAL. When the
results are compared to the ADL, it is
expected that the required (absolute)
method uncertainty requirement has been
met for the measurement. In this
document the required method uncertain-
ties are typically different for gross and
specific radionuclide measurements
because a different assumption is made
regarding tolerable error rates (see
Appendix VI).
The selection, validation, and execution of
a particular analytical method rely on the
ability of that method to produce a result
with the required specified uncertainty,
WMR, at the AAL. These conditions assure
that the quality of the final sample analysis data will be adequate for making critical decisions.
Whenever the reported sample activity or concentration exceeds a pre-defined decision level (the
ADL), appropriate action is warranted. The derivation and use of AAL, WMR, and ADL are
discussed in detail throughout this guide. While closely interrelated, it is important to note that
the use of AAL (and associated WMR) and ADL represent distinct concepts; they may not be used
interchangeably but rather should be interpreted and applied according the guidelines of this
document.
Action Levels: AALs and ADLs
This guide relies heavily on the use of the terms "analytical
action level" (AAL), "required method uncertainty" (UMR),
and "analytical decision level" (ADL) in characterizing the
desired levels of performance of analytical methods and the
radioanalytical results for use in decisions.
The term "analytical action level" is used as a general term
denoting the radionuclide concentration at which action
must be taken by incident responders. The AAL will
correspond to a PAG value (short-term dose-based) or a
risk-based value (related to long-term health effects).
Ideally, the Incident Commander (1C) will provide the
laboratory with the dose- or concentration-based action
level and the acceptable decision error rates. If not, this
guide provides "default" values. For example, the air
concentration of 226Ra corresponding to the 500-mrem
PAG is 1.8 pCi/m3. Tables 7A, 7B, 7C, and 7D show the
AALs associated with the 2-rem, 500-mrem, 10~4 or 10"6
risk values for selected alpha, beta, and gamma-emitting
radionuclides in soil.
Incident-specific action levels different from the ones used
in the tables may be promulgated. In these cases, the
corresponding AALs can be calculated as a linear function
of either the 500-mrem AALs or the 10~4or 10"6 risk values
(see Scenario 3 for an example of an event-specific AAL
calculated in this manner).
The required method uncertainty and ADL will change depending upon the acceptable decision
error rate. Tables provided in Appendix I list the AAL, ADL, and WMR values for the
radionuclides of concern. The tables present gross screening and radionuclide-specific
measurements for alpha and beta/gamma-emitting radionuclides. Derivation of the ADL values
for each of these tables can be found in Appendix VI. The listed AALs are applicable as default
values based on generic conversions of the dose level to concentration in soil for a specific
radionuclide. The Incident Commander (1C) may provide incident-specific action levels or
decision error rates that would supersede these values. In this case, the laboratory will need to
develop new tables for all values, using the process described in Appendix VI.
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Three generic scenarios for soil contaminated with radionuclides are presented together with a
flow chart and description of the processes associated with the laboratory handling of these
samples based on direction from the incident command. The direction to be followed may be one
of the following —
• Analyze the highest activity concentration samples first, or
• Analyze the lowest activity concentration samples first, or
• Analyze those samples first that have alpha activity concentration (by screening) of more
thanl03pCi/g —
or some other characteristic that the laboratory can measure using their screening
instrumentation.
In order to illustrate the typical decisions and actions to be taken by a laboratory for each
scenario, examples of the scenarios using theoretical samples and measurement results are
provided in Appendices II, III, and IV. These examples represent only three of many different
possible permutations and should not be construed as limiting. Each example is keyed back to
the steps in its respective generic flow diagram and notes.
These scenarios assume that the time period from taking the sample to the actual beginning of
the analysis by the laboratory will be short (on the order of one day). Samples received by the
laboratory will not have had any pretreatment performed. Sample drying, homogenization, and
representative sub-sampling will need to be accomplished by the laboratory staff based on their
established standard operating procedures and the guidance from the incident commander based
on the project MQOs. Any sample-specific preservation or storage requirements for samples that
are not to be analyzed immediately should be communicated to the laboratory by the incident
commander no later than the time of the sample shipment.
For the three scenarios discussed in this guide, it is assumed that field personnel have performed
some type of radiation detection survey of the samples prior to sending them to the laboratory.
Laboratory staff should request field-screening measurements and descriptions of the instruments
used if not received with the sample shipping papers. If appropriate, field personnel may
determine which samples are to be submitted first to the laboratory based on these survey results.
The laboratory's surveys and analyses of the samples are not intended to confirm the field survey
results. Significant differences between field and laboratory screening measurements may exist
as a result of:
• Short half-life of a particular radionuclide (either anthropogenic or naturally occurring
radioactive materials [NORM]).
o Samples saturated with ground water may have thorium progeny 212Pb (ty2 = 10.6 h)
and 212Bi (ty2 = 1 h) that are unsupported.
• High background radiation levels in the area where the samples were initially obtained.
o If the samples were screened in situ., the background from contamination over the
large area where the samples are taken may be promoting higher readings of the
samples.
• Ingrowth of progeny radionuclides.
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
o For an IND or incident at a nuclear power plant, several radionuclides form a
transient equilibrium (See Table 2). For many of these it will take days to weeks for
the equilibrium to develop after an incident. The activity will increase by a factor of
about two if transient equilibrium is in its early stages at the time the sample was
taken.
• Different responses by the field and laboratory instrumentation to the possible radiation
emission types. The response of an alpha/beta survey instrument may vary considerably
depending upon:
o The energy of the alpha or beta particle emitted by the radionuclides in the sample,
o Self shielding within the sample matrix, which will have an indeterminate effect, and
o The effect on the measured response.
Therefore, screening instrumentation should be calibrated for target radionuclides when
they have been identified. See Section 6 of the Uses of Field and Laboratory Measure-
ments During a Radiological or Nuclear Incident (EPA 2012c).
• Uncertainty of the measurements based on the sample to detector geometry, background
radiation, type of instrument used, etc.
• Dealing with soil samples, specific issues like sample self-shielding, hot particles, and
non-uniform distribution can create a large measurement uncertainty dependent upon the
type of screening instrument used and the skill of the analyst.
Laboratory staff may want to compare the two screening results to assess how the above issues
can affect their sample prioritization.
Specific Soil Sampling Protocols
Soil sampling will likely have two general techniques. The first will take place in all phases of
the incident. The Federal Manual for Assessing Environmental Data during a Radiological
Emergency (see references) expresses PAGs for soil in terms of activity per cm2. The manual
describes collecting a sample from an area 10 cm by 10 cm to a depth of 2 cm and assumes that
the soil density will be approximately 1.6 g/cm3. Based on these assumptions the total sample
size will be approximately 320 grams.8
Radioanalytical results and depth of deposition will be used to determine if the PAG or risk value
Analytical Action Levels identified in the tables in Appendix I have been exceeded. These values
are based on direct exposure and inhalation due to resuspension. The values given in these tables
are based on the assumption that the exposure period is going forward from the time of sampling.
A second technique may be used late in the intermediate to recovery phase. This would involve
core sampling to a specified depth of the soil. The specifics for this type of sample such as depth
of core, thickness of soil slices from the core, core diameter, and fraction of material to be
sampled/combined, as well as associated Action Levels would be identified in the MQOs/DQOs
by the incident command staff. No specific guidance on subsurface AALs for core sampling of
soil currently exists.
The exact mass needs to be measured as it will vary based on factors such as organic content, soil composition and
packing, and moisture content of the sampled material.
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Importance of Sample Radiological Screening and Particle Size Distribution
Neither an IND nor an RDD has been deployed, however, there have been several incidents
involving radioactive materials and explosives that yielded soil contamination that would be
similar to such an event. Two of the most serious events were the crashes at Palomares, Spain, in
January 1966 and at Thule Air Force Base, Greenland, in January 1968.
In both incidents, the conventional explosives that accompanied the bombs detonated during the
crash without setting off a nuclear explosion. The explosions in both cases ignited the pyrophoric
plutonium, producing a cloud of radioactive materials that was dispersed over wide areas. These
areas were contaminated with the radioactive material from the bomb components, principally
uranium, plutonium, and americium. The size and distribution of particles that resulted from
these events, and settled on the soils after the aerosols were dispersed, were non-uniform.
Figure 1 shows an autoradiograph of a soil sample from Palomares after it had been
homogenized.
The sample (used for the autoradiograph shown in Figure 1)
was homogenized and brought to grain size of between 125
and 250 jim. The white spots indicate the particles of
plutonium while the entire dark area is due to soil particles
without radionuclides. Visually the soil was homogeneous.
However when the autoradiograph was developed the
difference in size of the plutonium particles was evident even
though the soil was ground to a fine mesh. It is clear from the
autoradiograph that the size and distribution of these particles
was non-uniform.
In another recent research study9 using soils from both
incidents, other techniques were employed to assess not only
the particle size but oxidation states of the plutonium and
other actinides.
Figure 1 -Autoradiograph of Particles
from Palomares Incident
Furthermore, results from electron microscopy with Energy Dispersive X-ray analysis (EDX) and
synchrotron radiation (SR) based micrometer-scale X-ray fluorescence (micro-XRF) 2D mapping
demonstrated that U and Pu coexist throughout the 1-50 micron sized particles, while surface
heterogeneities were observed in EDX line scans. SR-based micrometer-scale X-ray Absorption Near
Edge Structure Spectroscopy (micro-XANES) showed that the particles consisted of an oxide mixture
of U (predominately UO2 with the presence of U3O8) and Pu ((III)/(PV), (PV)/(V) or (III), (IV) and
(V)).
Also from that study,
O.C. Lind, et al, "Characterization of U/Pu particles originating from the nuclear weapon accidents at Palomares,
Spain, 1966 and Thule, Greenland, 1968," Science of the Total Environment, 376 (2007) pages 294-305.
14
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Using SEM in SEI and BEI-mode (Figs. 2 and 3), the size of the particles is estimated to be between
1 um and 50 um for Palomares and 20-40 um for Thule (Table 1). However, the number of particles
is limited and the 241Am activity concentration of submicron particles are below the detection limits
(~0.1 Bq) for y-spectrometry. In addition, the particles tend to be imbedded in larger soil and
sediment aggregates and imbedded small sized particles are difficult to identify in SEM-EDX. Thus,
the particle sizes reported herein should reflect the high end of the size distribution pattern.
Taking all XANES results into account, it appears that the Palomares and Thule particles contain a
mixture of U (predominately IV with the presence of VI) and Pu ((III)/(IV), (IV)/(V) or (III), (IV) and
(V)), most probably in the form of mixed-oxides/oxyhydroxides and not as ordered actinide-O2
structures.
In both studies, the soils were initially dried and then brought to a specific particle size range,
followed by analysis for gross radioactivity. The gross measurements were made either by
survey instrument, gamma spectrometer, or using autoradiography to assess sample
homogeneity. It also is important to note that the radioactive material in some cases had become
incorporated with larger soil aggregates. This likely occurred as a result of aging and weathering
of the soils before the sampling occurred.
The time dependence of the change in particle size, change in oxidation state of the radionuclides
present, or depth of penetration into the sampled medium was not a part of either of these
studies. Depending upon the type of incident, radioactive material involved, chemical reaction
leading to the dispersal of materials and weather conditions, different soil penetration and
particle aggregation will occur. However, no other easily-obtainable references have been
reported in the open literature since these incidents occurred that identify how the concentration
in the surface soil would change as a function of time.
The importance of these studies as they relate to either an IND or RDD is that they:
• Identify the non-homogenous distribution of the particulate matter (soil) that may exist in
the soil samples,
• Demonstrate the variety of particle sizes (associated with the radionuclide) that may be
formed or exist, and
• Show the variation in oxidation state for actinides if present.
Analysis of these samples by gamma spectrometry and radiography (as in the above references)
requires adequate homogenization but does not require rigorous dissolution of the samples to
identify the gamma emitting radionuclides or "hot" spots. The radiographic evidence has shown
that discrete radioactive particles (DRPs) do exist in an RDD-type incident. In any radiological
event where temperatures are elevated to the thousands of degrees Fahrenheit, DRPs would also
form and likely be refractory. Such DRPs would be of an entirely different composition than the
soil they contaminate. This makes the analysis of non-gamma-emitting radionuclides more
difficult and emphasizes the need for soil dissolution techniques that completely dissolve the
sample, including DRPs. Because chemical separation techniques are required for the non-
gamma-emitting radionuclides, additional oxidative-reductive processes may be necessary in
order to bring the radioisotopic species present to one, common oxidation state.
15
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Laboratory Preparation of Samples
Only laboratories using validated radioanalytical methods (see MARLAP, Chapter 6) should be
used in order to process samples in a timely and effective manner. These laboratories will have
the necessary radioanalytical capability and sample-processing capacity to conduct the gross
screening and radionuclide-specific analyses defined for the radioanalytical scenarios in a timely
and effective manner. This guide recommends the following analytical process flow by the
laboratories when soil samples are received.
1. General screening based on radiation emitted from the sample (i.e., alpha, beta, and
gamma).
2. Initial homogenization of the bulk sample so that aliquants removed will have a high
probability of being representative of the whole sample if analysis of volatiles is needed.
3. Sample pretreatment involving drying (when applicable), further homogenization (e.g.,
ball mill treatment), and sieving and blending (to permit taking of smaller representative
subsamples if required by the incident data quality objectives).
4. Sample treatment by leaching or complete dissolution by hydrofluoric acid digestion or
salt fusion technique.
5. General radiological screen of individual fractions using liquid scintillation or gas
proportional counting following dissolution.
6. Comparison of the pre- and post-sample treatment/dissolution screening values.
7. Specific radioanalytical techniques applied after dissolution for the samples designated as
priority by the incident command (may be highest or lowest activity concentration
samples that are the priority).
These steps are shown in Figure 2.
This is the sample preparation sequence used for radioactivity screening in the flow diagrams for
each radioanalytical scenario described in this document. A sample aliquant may be taken
following any of the steps in this process as no sample preparation except for homogenization is
necessary. Thus an analysis by gamma spectrometry could be done after Step 2, 4, or 6. Each of
the yellow boxes in Figure 2 represents an action that should be stipulated by the incident DQO
and MQO statements. For example yellow box B states the detritus removed from the sample is
separately assessed for radioactivity. This action would be a project-specific requirement and
separate MQOs would need to be established for this situation.
The three scenarios described in Sections IV, V, and VI each contain a flow diagram where a
decision point in the flow diagram relates to an action level (PAG, regulation, or risk-based dose
limit). It also is important to note that the AALs and MQOs will likely be different for the
screening process versus the radiochemical determination steps. Many of the flow diagram boxes
have numbers indicating the sequence of the analytical process. The boxes are color-coded
indicating the most important flow path (red) to the least important (yellow) based on the time
requirements for returning the analytical results.
16
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
1. Sample container
screening
2. Coning and quartering
bulk detritus removed
3. Dry
110 F
A. Dose rate
assessmentand
contamination
potential
C. Aliquant removed
For volatiles analysis
< a.Radiochemieal analysis of
volatiles
prior to drying
6. Sample dissolution
by fusion or acid
7. Aliquantingfor
radiochemical
specific analyses
(except volatiles)
E. Gross activity
assessment compared
to initial screen:
assess contamination
potential
4, Sample homogenized
via shaker/mill to
visually obtain small
mesh size
D. Identify in homogeneous
particles and remove
or repeat
homogenization
Figure 2 - Initial Screening and Pretreatment Process
The screening techniques10 outlined in the first steps of the flow charts assume that the laboratory
is equipped with instrumentation that can perform the screening functions identified below:
• Micro-R meters that can be used to evaluate radiation exposures or doses on incoming
samples.
• Hand-held gross alpha detector that can be used to assess the alpha contamination of
container surfaces by swipe analysis.
• Determine the alpha count rate directly on the sample surface (although this may not be
very effective except for those cases of very high alpha contamination levels).
• Thallium-activated sodium iodide (Nal(Tl)) or high-purity germanium (HPGe) detectors
that can be used in energy or total counting modes to perform gross gamma activity
analysis of samples. (Laboratory staff must ensure that they are using library data from
the National Nuclear Data Center [www.nndc.bnl.gov/1 or another recognized source of
nuclear data that will be comparable.)
The laboratory also should have the instrumentation to perform radionuclide-specific analyses
(e.g., liquid scintillation , gamma spectrometry, and alpha spectrometry).
Specific recommendations for sample screening processes are identified in Radiological Laboratory Sample
Screening Analysis Guide for Incidents of National Significance (EPA 402-R-09-008, June 2009).
17
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Each numbered box has associated with it a note that provides additional detail for that particular
part of the process. Clarification also is provided in these notes as to when parallel paths of
analysis should be followed to help expedite the processing of samples.
Appendix V contains an example of a spreadsheet using generic assumptions that can help
laboratory personnel in assessing count times for samples. The spreadsheet demonstrates how the
user can determine the time it will take to achieve the required method uncertainty for the
decision points in the flow diagram for two different screening methodologies. Laboratories
should prepare their own spreadsheets, in advance of an event, using their preferred
methodology. Laboratories also should determine (in advance) whether their individual
analytical protocols will need to be revised to accommodate this process. The flow charts used in
this document that describe the screening process use gas proportional counting for the aliquant
sizes and count times. However, liquid scintillation also may be used for this process. In both
cases the laboratory should have a validated method that provides appropriate guidance to
laboratory staff on how the screening results relate to overall sample activity concentration.
Appendix V has approximate times and sample sizes for this method of analysis as well.
The number of samples that will be analyzed, and their level of contamination, may be
significantly higher than normal samples. Laboratories should use the guidance provided in
Guide for Radiological Laboratories — Identification, Preparation, and Implementation of Core
Operations for Radiological or Nuclear Incident Response (EPA 201 Ob); Guide for Radiological
Laboratories for the Control of Radioactive Contamination and Radiation Exposure (EPA
2012b); and A Performance-Based Approach to the Use of Swipe Samples in Response to a
Radiological or Nuclear Incident (EPA 2011) when:
• Assessing the need for separate sets of procedures for sample handling and storage.
• Increasing the frequency of detector background analyses.
• Increasing the frequency of quality control (QC) checks.
• Adjusting the QC check activity concentration level to more closely align with the
activity concentration of the anticipated samples.
• Increasing the frequency of contamination assessments (i.e., smears/swipes) on working
surfaces in the laboratory.
• Writing separate protocols for personnel protective equipment.
• Writing separate protocols for personnel and sample radiation monitoring.
• Creating separate storage location for high activity concentration samples or a large
group of samples that would increase laboratory background for detectors or increase
exposure to personnel.
It should be noted that the procedures that have been in place for the last 30 years may have been
modified to account for the low concentrations of anthropogenic radionuclides normally
encountered. Should an RDD or IND be deployed, and it contains a radionuclide that has
radioactive progeny, it is possible that the radioactive equilibria involved with these progeny will
have been established. This means that not only will there be considerably higher concentration
of the parent but of each of the progeny. Furthermore, if multiple radionuclides are involved, the
cross-contamination factor during separations must be minimized, a phenomenon that current
day analysts may not have previously experienced.
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
A specific example of such a phenomenon would be the elimination of 140Ba (£/2 = 12 d) during
the 90Sr separation process. Currently, several methods in use do not account for 140Ba removal.
TM
Strontium-specific resin separations (for example using an Eichrom resin) use 8 M HNOs to
minimize retention of barium. However, this method is not designed to remove large amounts of
interfering beta emitters (-1,000 times greater than 90Sr levels). In these instances of samples
with very high beta activity, it will be beneficial to perform a double column separation to ensure
adequate removal of such beta interferences. Generally, the most likely source of this
radionuclide would be a release from a nuclear power plant.
Analysis of soil samples for radionuclides represents a more difficult process than for water or
air samples. This is not only due to the different types of soil presenting challenging matrices to
digest during sample preparation, but also due to the presence of measurable concentrations of
several different naturally occurring radionuclides. The decay products of uranium and thorium
can provide a significant gross activity measurement to some soils when no anthropogenic
sources are present.
Each natural series has lead, bismuth, and polonium radionuclides that are related via direct
equilibrium. The radium isotopes decay to these radionuclides via different radon gas
radioisotopes. This can cause significant differences between in situ field measurements and
laboratory screening measurements. Such differences may have an effect on the prioritization
assigned to a specific sample.
Furthermore, soils contain 137Cs and 90Sr from atmospheric bomb testing that occurred during the
time period of 1950-1980. Although the mean concentrations are typically very low (-0.2 and
-0.05 pCi/g, respectively) and will not affect screening results, the soil concentrations of these
radionuclides should be established before using new data to assess spread of contamination in
the event these radionuclides were used in the RDD event. EPA's Response Protocol Toolbox
(EPA 2004) provides additional recommendations concerning planning and threat management,
site characterization and sampling, and sample analysis to assist utilities and state and local
agencies. If laboratory protocols for non-emergency situations cannot ensure that the DQOs and
MQOs are achievable with the laboratory's standard operating procedures (SOPs) under
emergency conditions, then a separate set of SOPs for incident conditions will need to be
developed.
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
IV. RADIOANALYTICAL SCENARIO 1 (IDENTIFYING SAMPLES WITH HIGHEST
ACTIVITIES)
1. Sample container
exterior screened
for a, p, y
2b.
Sample screening
y>590
pCi/g?
e screening
Y>160rp>3,200
a>210
Ci/g?
la. Sample is
screened for a. P, y
12. Process lowest
priority samples
when capacity is
available
rung/quartering;
Non-volatiles I Volatiles
Dry. pulverize.
ogenize. and
uant for non-
latile analyses
Key
^H Highest priority
I I Second priority
Lowest priority
I I End result
omogenize
and aliquant for
ile analyses
h. low-
perature
digestion or basic
fiisirm
See accompanying tables
for alpha and beta/gamma
concentrations, and
numbered notes
a. Sample fusion.
acid digestion
7a. Analysis for _ |
a emitters a Yes p B emitters
: Analysis for
lew and report results.
divi
=•
oraolete narrative.
Figure 3 - Radioanalytical Scenario 1 (Identifying Samples with Highest Activities)
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Notes to Scenario 1: Source of Contamination: Unknown
Purpose: Priority to Those Samples with Highest Activities (early into
intermediate phase) — Greater than the 2,000-mrem PAG
Highest priority samples should be analyzed first. Only after the highest priority samples have at least
been started (excess capacity available) or completed should lower priority samples be addressed. The
samples may arrive over several days. Lower priority samples (those following the green and yellow
flow paths on this chart) may need to be stored for several days until the highest priority samples have
been analyzed.
The radionuclide activities corresponding to PAG values for this scenario can be found in Tables 6A
and 6B for screening and 6C and 6D for radionuclide-specific activities.
The determination of gross y, a, and P sample concentration relative to the PAG values is
left until the next step. Sample container exteriors are surveyed to assess whether there is
indication that contamination is present.
These might include a Geiger-Mueller counter with appropriately calibrated beta and
gamma detector probes or a micro-roentgen meter (gamma only). l This step should be
performed with the sample container unopened. Surface swipes of the container are taken
to assess for external gross a/P and y contamination. These surveys are for contamination
control purposes and not for the assessment of sample processing flow path.
Any container with measurable external contamination should be decontaminated before
proceeding with subsequent analysis. This will help to minimize sample cross-contamina-
tion as well as laboratory contamination.
Gamma Screening
Unless the identity of the radionuclide contaminant(s) is known, the screening instrument
should be calibrated for 60Co.12 MQOs will correspond to those defined for 60Co first year
2,000 mrem PAG for screening measurements (see Table 6B). A 60Co source distributed
through a 300-gram soil matrix counted in the same geometry as the sample should be
used for calibration of the screening instrument.
If a limited list of radionuclides of concern is known, it may be practicable to use a
calibrated Nal(Tl) detector to assess gross gamma activity concentration and relate this
measurement directly to a PAG concentration. The gross gamma activity concentration
can be determined using either a Nal(Tl) or HPGe detector using the total counts between
40 and 2,000 keV accumulated over a short time period (about 10 minutes).13
11 Some manufacturers have developed kits that include the survey meter plus an alpha-beta-gamma pancake GM
detector and a Nal gamma detector.
12 The gross gamma activity as determined by integrating the entire spectrum of a Nal(Tl) or HPGe detector above
about 40 keV. Appropriate efficiency corrections for each detector would need to be applied.
13 Radiological Laboratory Sample Screening Guide for Incidents of National Significance, EPA 402-R-09-008
(June 2009).
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Some gamma-emitting radionuclides may not be detected at their PAG concentration
levels if the sensitivity of the instrument used is inadequate, or for very low-abundance or
low-energy gamma emitters. Radionuclides that do not emit y- or X-rays greater than
approximately 40 keV (including pure alpha and beta emitters such as 210Po or 90Sr) may
not be detected. If multiple gamma ray emitting radionuclides are known to be present, it
may be difficult to assess if an AAL has been exceeded with a gross gamma
measurement. It may be possible to identify samples where an AAL for a gamma emitter
will not be exceeded. By calibrating the survey instrument using the beta/gamma
radionuclide having the "limiting AAL" for the 1000 mrem PAG listed in Table 6B and
the geometry used for the screen the gross gamma measurement can be compared to the
respective "limiting" ADL.14
Gross Alpha and Beta
The methods described here present a rapid, positive approach to screening of soils, involving
digestion or aliquanting methods commonly used in the radiochemistry laboratory; it requires
open handling and processing of samples that may contain elevated levels of radioactivity.
Laboratory staff will need to take specific precautions while performing these techniques to
avoid personal contamination (including inhalation), laboratory surface contamination, and
sample cross-contamination since the radioactivity level of pure alpha or beta emitters in the
sample is unknown. The lab should develop guidelines for their staff outlining the personal
protective equipment required for different levels of gross alpha or gross beta activity based
on screening results. Additional precautions should be taken to have a separate area for the
screening process.
The samples received from a radiological incident may come in a variety of containers:
plastic bags, plastic bottles, glass bottles, Petri-style containers, aluminum cans, etc. The
masses of the samples received also will vary significantly. If possible, using several
different style containers with different masses of standards for use in calibration of
screening equipment will be helpful in minimizing the time for the initial sample
screening process.
Screening of the sample for a and P activity must be done carefully as the gamma screen
may not yield any indications of elevated activity concentration when only pure alpha- or
beta-emitting radionuclides, or radionuclides that only emit y- or x-rays below the
calibrated range of the instrument. A very rudimentary screening process, performed in a
hood, should be used prior to removing the entire sample from its container for
homogenization and sub-sampling. Some options for making such a measurement may
be:
14 The limiting AAL and ADL for gross gamma measurements cannot be used to demonstrate that an individual
AAL has been exceeded, rather it can only show that an AAL will not be exceeded obviating the need to perform
further gamma measurements. The limiting AAL is the one that produces the lowest gamma response at its
respective AAL (i.e., the lowest product of AAL and gross gamma efficiency). It is most reliably determined by
calibrating the detector for gross gamma in the geometry to be used with each gamma-emitting radionuclide that
may be present. This approach may not be practicable if a large number of gamma emitters may be present.
22
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
• Take a swipe of the inside of the container cap. Then, using an alpha-beta probe,
determine the count rate of the swipe.
• Insert a tongue depressor (with double-sided tape on one surface) into the container
and remove for direct measurement.
• Take a small aliquant of the top surface (after the sample container is shaken) and
spread it onto a planchet.
• Take a measured aliquant and place it into a scintillation vial with cocktail for liquid
scintillation analysis.
• Perform a rapid nitric-hydrofluoric acid digest (total dissolution is not necessary) on a
small aliquant of the sample and evaporate onto a planchet.
For the first three bullets above, an initial estimate of the mass transferred using the
specific technique should be made with a soil of similar composition. The probe used for
such techniques should have been calibrated with soil samples spiked to a level
simulating the AAL values.
The last two options above, LSC and gas proportional counting (GPC) may provide more
quantitative measures for gross alpha/beta screening of samples. Note that a screening
method that evaluates gross alpha/beta activity concentration directly on soil is not
included.
LSC can provide a faster screening process and avoid some of the shortcomings of a
simple sample leaching process needed for GPC because the effects of self-absorption in
the sample test source are minimized using LSC. The procedure used must correct for
quench from various sources in the soil, and the method must be validated prior to use on
samples from an incident. It may be impractical to separate alpha from beta signals using
pulse-shape analysis in the case of high levels of quench. Instead, a total activity
measurement (combined alpha and beta) across the entire energy spectrum may provide
the most reliable estimate of activity in highly quenched samples.
For soil samples, the question arises of how to introduce a representative sub-sample into
the liquid scintillation matrix. Although there are no standard methods that specifically
address this issue, several general approaches are commonly used. The first, perhaps
more conventional approach, involves direct measurement of the solid; the second
involves leaching or digesting a representative aliquant of the solid sample and
processing the leachate / digestate as if it were an aqueous sample. The third approach
involves directly suspending a small, representative aliquant of the soil in a gelling liquid
scintillation cocktail.15
The limiting factor in using gross alpha beta measurements for reliable decisionmaking is
obtaining a representative aliquant. In contrast to the gamma measurement where the
entire sample is usually measured, the relatively small portion of unhomogenized sample
may not be representative of the entire sample. The small aliquant used may fail to
15 Cocktails such as Insta-Gel, or Quicksafe A may be used since they will suspend the solid and allow it to be
counted in a 4-rt geometry.
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
identify non-homogenously distributed activity present in a sample. The alpha / beta
screen may still provide important information with regard to handling and the need for
personal protective measures since the next steps involve working with the entire sample
outside of the sample container.
The gross radioactivity measurements used for comparison in Step 2 are taken from the ADL
values shown in Tables 6A and 6B (60Co for gamma; 226Ra for a, and 90Sr for (3) for the 2,000-
mrem PAG. These represent the ADL values for the listed radionuclides that are likely to be
present.
No conclusions about the presence or absence of these or other radionuclides should be made
at this point in the analytical process.
The laboratory should weigh the time spent performing screening at these low concentrations
versus the time taken to perform radiochemical-specific sample analysis.
While gamma measurements may meet MQOs for required method uncertainty prior to
complete homogenization of the sample, high levels of uncertainty associated with the
alpha/beta screening techniques discussed above may preclude use of the gamma
measurements for making reliable screening decisions until a representative aliquant can
be obtained following homogenization of the sample. It is important to ensure that
estimates of the measurement uncertainty are robust, and that MQOs for uncertainty have
been met before using data to decide that a sample concentration exceeds an AAL. If
estimates of uncertainty are deemed to be unreliable, the results should not be used for
critical decisionmaking. Thus it may be necessary to delay decisions about whether
AALs for non-gamma-emitting radionuclides have been exceeded until the sample is
milled and homogenized and a representative aliquant can be obtained.
Measurements resulting from the screening process that satisfy the MQOs for required
method uncertainty are compared to the limiting ADL corresponding to the first year
2,000 mrem PAG16 to determine if an AAL may have been exceeded. Samples that
exceed the default gross screening ADL values for gross alpha of 210 pCi/g, or gross beta
of 3,200 pCi/g, or gross gamma of 160 pCi/g will take the red path (highest priority). If
the values for gross alpha and beta are taken as an aggregate measure (i.e., the sum of the
gross alpha and beta activities), then the more restrictive ADL value of 210 pCi/g for
alpha response is used to assess if the screening ADL has been exceeded. Samples that
exceed the values identified in this step stay on the red path and go to Step 3.
Sample results that exceed either of these values should be communicated immediately to
the 1C so that decisions regarding the elevated activity concentration from these sample
locations can be made in a timely fashion. This feedback also will reinforce the priorities
assigned to each sample and further enhance decisionmaking.
16 Depending on the time of the response, a 1,000-mrem PAG for the first four days of exposure may be requested
by the incident command. If so, use the radionuclide concentrations corresponding to the 1,000-mrem PAG in
Tables 6Aand6B.
24
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Samples with a combined alpha + beta + gamma activity of greater that 59017pCi/g are
placed on the green flow path and analyzed when time permits after completing the red
path analyses. Lower activity samples are stored for analysis after all higher priority
samples have been processed (see Step 12).
NOTE: The dashed lines connecting Boxes 2a, 12, and 3 in the flow chart indicate that
analyses for short-lived or volatile radionuclides may need to proceed more quickly due to
concerns about short half-lives or chemical stability of the target radionuclides.
A process described as "coning and quartering" is used to break the entire bulk sample
down into representative subsamples. Coning and quartering of the sample provides
reasonable assurance that subsamples will be representative of the whole sample. Unless
the project has a specific MQO to the contrary, remove extraneous detritus (e.g., sticks,
twigs, rocks larger than 1/4", etc.) prior to "coning and quartering." The material
removed from the sample should be retained for potential future analysis and an
appropriate comment added to the case narrative.
Fractions are isolated for volatile radionuclides and gamma spectral analysis (Step 4b),
and for analysis of non-volatile radionuclides (Step 4a), where required. The volatile
fraction should be processed quickly and immediately sealed in containers to minimize
potential losses of volatile radionuclides.
The details of subdividing the sample can be found in Rapid Method for Fusion of Soil
and Soil-Related Matrices Prior to Americium, Plutonium, and Uranium Analyses; Rapid
Method for Radium-226 Analyses in Soil Incorporating the Fusion of Soil and Soil-
Related Matrices; and Rapid Method for Sodium Carbonate Fusion of Soil and Soil
Related Matrices Prior to Strontium-90 Analysis (EPA 2012a). The volatile fraction
should be processed quickly and immediately sealed in containers to minimize potential
losses of volatile radionuclides.
Precautions should still be taken (e.g., opening the sample container and handling in a
hood) since the alpha/beta activity concentration has only been assessed by bulk
screening techniques.
The homogenization and size reduction can be accomplished using an approach such as
that described in the above-referenced method (EPA 2012a). This approach has been
used on smaller scales than that described in ASTM C-99918 and would facilitate
preparation of representative samples for a batch in approximately 2 hours time.
17 The value of 590 pCi/L is derived from, 160(gross gamma) +210 (gross alpha) +220 (lowest ADL for a beta only
emitter 227Ac). The 227Ac is used since there is a potential for this being an IND type scenario.
18 ASTM C-999, Standard Practice for Soil Sample Preparation for the Determination of Radionuclides.
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Place the non-volatile fraction isolated in Step 3 in a tared can. Remove the lid and dry to
constant weight in an oven at 110±10 °C. Drying samples provides for consistent
comparison of results regardless of moisture content.
This is the dry-weight basis for the analysis. This mass is also used to calculate the
fractional solids content for each sample (i.e., percent solids) so that results from the
volatile fraction, analyzed "as received" can be converted to and reported on a dry-weight
basis.
Constant weight may be determined by removing the container from the oven and weighing
repeatedly until the mass remains constant to within about 1%. This also may be achieved
operationally by observing the time needed to ensure that 99% of all samples will obtain
constant weight.
Once the sample is dried, milling and homogenization continues using the same vessel
(the paint can). Stainless-steel or ceramic balls or rods are added to the can and the can is
shaken for about 5 minutes, or as needed to produce a finely-milled, well-homogenized,
sample. The precise particle size of the milled sample is not critical as long as the milled
sample is fine enough to facilitate rapid and complete dissolution of the soil matrix
during the dissolution process.
NOTE: A qualitative, visual standard can be prepared by passing quartz sand or other milled
material through a 50-mesh and then a 100-mesh screen. The portion of the sample retained in
the 100 mesh screen can be used as a qualitative visual standard to determine if samples have
been adequately pulverized. The process is complete once 95% of the sample (or greater) is as
fine, or finer, than the qualitative standard. If, by visual estimation, more than -5% of total
volume of the particles in the sample appear to be larger than the particle size in the standard,
return the sample to the shaker and continue milling until the process is complete.
If, by visual inspection, the sample appears to contain larger particles that may not be
effectively dissolved during the fusion or digestion process, those particles may be
preferentially removed prior to aliquanting. In most cases, removal of a small fraction of
larger particles will still provide representative results because the surface area of larger
particles is relatively low and the surface will be abraded during milling. As a result, the
activity associated with sample fines should be representative of that found in the original
sample. A comment should be added to the sample narrative addressing removal of the
solids.
The details of the milling and homogenization process are presented in Rapid Method for
Fusion of Soil and Soil-Related Matrices Prior to Americium, Plutonium, and Uranium
Analyses; Rapid Method for Radium-226 Analyses in Soil Incorporating the Fusion of
Soil and Soil-Related Matrices; and Rapid Method for Sodium Carbonate Fusion of Soil
and Soil Related Matrices Prior to Strontium-90 Analysis (EPA 2012a).
26
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
At this point, representative aliquants of the dried, homogenized sample can be taken for
radionuclide-specific analysis for non-volatile components. A separate aliquant is also
removed for gross alpha and beta screening and subjected to the same dissolution process
as are samples for radionuclide-specific analyses. Note that no tracers/carriers are added
to the gross alpha beta aliquant as these will interfere with the determination of gross
alpha and beta activity.
Prior to or concurrent to Step 5a, soil samples with significant organic content should be
ashed to completely combust organic matter. This can be accomplished using a
programmable furnace where a temperature of approximately 600 °C can be achieved.
Ramping up the temperature in time intervals is necessary to avoid uncontrolled ignition
and excessive smoke generation during the process. If the sample is ashed prior to
aliquanting, record the wet, dry, and combusted weights so that the wet/dry ratio (i.e.,
percent solids) and the percent organic content (if required) can be calculated and used to
convert final results to a dry-weight basis
Representative portions of the undried sample fraction are aliquanted as needed for
analysis of volatile radionuclides and for HPGe gamma analysis. The sample should be
mixed, homogenized, and subsampled rapidly and in a manner that ensures that
minimizing loss of volatiles and that aliquants will be representative of the original
sample.
Aliquant size should be planned to optimize count times and throughput while ensuring
that method uncertainty requirements are met.
Analyses for volatile radionuclides should be started as soon as possible to minimize loss
of analyte. If sample analysis cannot be started immediately, a project-specific means of
sample storage for volatiles should be in place so that even short-term storage does not
significantly reduce their concentration.
Steps 5 and 6 can be performed concurrently.
Non-volatile radionuclides are prepared for chemical separations using validated
techniques for total dissolution of the sample. The dried or ashed aliquant of the sample is
dissolved to create one or several stock solutions, as appropriate for the analyses to be
performed.
For samples resulting from an RDD, it is important to achieve complete dissolution.
Certain materials such as those used in a radioisotope thermoelectric generator (RTG),
brachytherapy sources, or matrices that have been exposed to a high temperature
detonation, may be difficult to dissolve using conventional acid digestion techniques.
Sodium carbonate or sodium hydroxide fusions are two good methods for obtaining
complete dissolution of soil samples.19 Fusions help ensure isotopic exchange of analyte
19 Fusion processes are presented in detail in Rapid Method for Fusion of Soil and Soil-Related Matrices Prior to
27
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
with the tracer or carrier in the homogeneous melt formed. Soil dissolutions using
hydrofluoric acid (HF) may not effectively solubilize certain refractory materials, but
they can be very effective in completely dissolving a variety of matrices including poorly
soluble silica-based materials.
Volatile radionuclides are prepared for chemical separations using validated techniques
for dissolution of the sample. The sample aliquant is dissolved to create one or several
stock solutions as appropriate for the analyses to be performed.
To prevent volatilization of analyte during dissolution, samples should be dissolved prior
to chemical separations using techniques validated for the volatile radionuclides of
concern. Low temperature digestion, basic leaching, or basic fusion techniques, combined
with appropriate oxidation/reduction control may be used to maintain radionuclides in a
non-volatile state throughout the process.
The sample fraction isolated for gamma spectrometric analysis in Step 4b is counted on a
HPGe spectrometer. Aliquant size should be planned to optimize count times and
throughput while ensuring that method uncertainty requirements are met.
The HPGe analysis is routinely performed on the "volatile" or "as-received" fraction of
the sample. Analysis of this fraction will produce results that are valid for all gamma
emitters, volatile or non-volatile. Results performed on the "as-received" sample are
converted to a "dry-weight" basis by applying percent moisture results determined in
Step 4a.
The volumetric configuration and density of the sample should be as close as possible to
the calibration standard. Every soil sample will have some naturally-occurring
radionuclides present. A sample with similar soil composition from a representative non-
impacted area may help in determining the radionuclide concentration levels of
background radionuclides in uncontaminated soil.
If sample size is limited, the prepared sample from this step may need to be shared with
the fusion, digestion, leaching processes in Steps 5a or 5b.
Once the sample is homogeneous, it is possible to withdraw a representative aliquant of
the fusion, digestion, or leaching processes in Steps 5a and 5b for analysis for gross alpha
and gross beta activity. After the source radionuclide(s) has been identified, it may be
possible to eliminate one of the screens depending on the volatility of radionuclides that
may be present in the sample. If it is known that only gamma-emitting radionuclides are
present in the sample, and if all MQOs can be met, screening measurements in Step 7 and
radionuclide specific measurements in Steps 7a and 7b may be skipped in lieu of the
gamma measurement in Step 6.
Americium, Plutonium, and Uranium Analyses; Rapid Method for Radium-226 Analyses in Soil Incorporating the
Fusion of Soil and Soil-Related Matrices; and Rapid Method for Sodium Carbonate Fusion of Soil and Soil Related
Matrices Prior to Strontium-90 Analysis (EPA 2012a).
28
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Assuming that the MQO for required method uncertainty for alpha screening of 130
pCi/g at the AAL of 410 pCi/g is met (corresponding to the first year 2,000 mrem PAG
for 226Ra in Table 6A)20, and the alpha concentration is greater than the ADL of 210
pCi/g, the sample will be analyzed for a-emitting radionuclides using radionuclide-
specific methods. Assuming that the MQO for required method uncertainty for gross beta
screening of 3,200 pCi/g at the AAL of 330 pCi/g (first year 2,000 mrem PAG for 60Co in
Table 6B) is met, and the beta concentration is greater than 3,200 pCi/g, the sample will
be analyzed for radionuclide-specific 3-emitting radionuclides.
If a screening technique is used that provides an aggregate value for the radioactivity
(i.e., it does not differentiate between alpha and beta activity but reflects their summed
total) greater than 210 pCi/g, the sample should be analyzed for radionuclide-specific
alpha-only and beta-only emitters. If MQOs are met, but the gross activity is less that the
above values, archive the remainder of the fused sample for analysis at a later time and
report results to the 1C per step 11.
The laboratory should validate screening techniques for concentrations at the AAL for the
1,000-mrem and 2,000-mrem PAG values.
If the gross alpha or beta concentration exceeds the ADL for either of these groups of
emitters, chemical separations should be started immediately using validated procedures
for each analysis to be performed. If the project manager does not specify the sequence of
analyses, laboratory personnel should use their best professional judgment, based on the
characteristics of the samples, to determine the order of processing the samples so that
the results are obtained in the timeliest manner.
All analytical results should be collected for each sample (both the screening values and
the final radiochemical-specific analyses). The results should be reviewed and reported
by knowledgeable personnel per the laboratory's QA program.
As reviews are completed, and finalized radionuclide-specific results become available,
each individual result can be compared to project-specific MQOs and ADL values (see
Tables 6C or 6D for default values). For example, from Table 6C, the required method
uncertainty for 241Am is 140 pCi/g at the AAL of 1,100 pCi/g. The ADL for the 2,000-
mrem PAG is 780 pCi/g. If the MQO for required method uncertainty is met, and the
activity concentration exceeds its ADL, the 2,000-mrem AAL has been exceeded. The 1C
should be promptly notified (broken line to Step 11) while the remaining analytical work
is completed.
Compare the sum of all final analytical results that are above their respective critical level
concentrations with the sum of the respective gross radioactivity measurements. This is
done to verify that no major radionuclide contributor to dose has been missed. Isotopic
and gross screening results should agree with each other within a factor of about two.
20 This is the limiting default value for all the listed radionuclides. If a shorter list of possible radionuclides is
known, use the limiting value from that list.
29
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Discrepancies in agreement may indicate that a major radionuclide may have been
omitted from the analysis sequence in Steps 6, 7a, or 7b, or they may be attributable to
problems with the analytical process. They may also indicate that the screening process
needs to be adjusted based on the specific radionuclides identified in the samples.
Comparability may not be realized for volatile radionuclides, when radionuclides with
low-energy emissions (beta-gamma, conversion electrons, x-rays, etc.) are present.
Difference may also result when radionuclides with short-lived decay progeny are in the
mix of radionuclides in the sample. For example, if 103Ru is detected by gamma-ray
spectrometry, its progeny 103Rh may not be specifically identified by the software, even
though it is present in secular equilibrium within hours. Significant unreconciled
differences between the screening and the summed radionuclide-specific results should
be noted in the report to the 1C.
The sum of fractions (SOF) for all radionuclides present is calculated at this point. This is
done by dividing each individual radionuclide concentration that exceeds its critical level
by its respective AAL value (see Table 6C or 6D for default values). The calculation of
the sum of fractions uses the following equation:
11
Sum of Fractions = y
[AAU
Where R{ is the activity concentration of the individual radionuclide and AAL; is the
analytical action level of that radionuclide for the 2,000-mrem PAG concentration at one
year of exposure. If the sum of fractions is greater than 1.0, the 2,000-mrem PAG AAL
concentration for the first year exposure may have been exceeded. The case narrative is
updated accordingly.
Contact the 1C and report all final results, and whether or not individual analysis, or the
sum-of-fractions results, identifies that a PAG AAL has been exceeded. All sample
residuals or residual solutions from dissolution should be archived in the event that
additional analyses are required.
12 Samples that do not exceed the gross screening values in Step 2b are given lower priority.
Analysis of these samples may be delayed at least until analyses for red and green path
samples have been started unless there is concern about decay of short half-lived
radionuclides in the sample. Samples that fall into this category based on initial screening
results may be communicated to the 1C so that decisions regarding the first-year exposure
pathway PAGs level of activity concentration from these sample locations can be made in
a timely fashion. Although there may be some question regarding the representativeness
of these results, this feedback may help shape priorities assigned to each sample and thus
enhance decisionmaking.
30
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Additional Points for Scenario 1:
Volatiles
Volatile radionuclides that are most likely to be encountered are 131I 129I, 125I, 3H (tritium), and
99Tc. The normal preservation techniques of a sealed container and low temperature will
minimize the loss of these radionuclides in a soil sample during transport and sample handling
(both in the field and in the laboratory). If it is determined that radioisotopes of these elements
are present, sample acquisition techniques, handling, storage, and shipping may need to be
modified to further minimize potential losses. Such techniques may include:
• Sample techniques that minimize sample aeration when transferring from the ground to
the sample container.
• Use of small containers so that the sample completely fills the container.
• Use of an electronic or dry ice cooler to immediately reduce sample temperature.
For measurement of tritium in soil samples (where 3H is incorporated solely as part of a water
molecule), relatively simple techniques such as freeze drying or distillation following
equilibration with a minimal amount of water carrier provide good separation from the remainder
of the matrix. More involved chemical methods are necessary to ensure adequate separation and
capture of the radioiodines or technetium.
Screening of Soil Samples
Screening samples for gross y activity concentration is much easier than screening for gross a or
gross beta activity concentration. Analysts should recognize that the degree of self-absorption
will limit the size and representativeness of sample that can be effectively analyzed for gross
alpha or gross beta, and may introduce substantial bias and uncertainty into direct measurements
of soil samples. Gamma rays, however, are not as significantly affected by the soil matrix, which
means that larger more representative samples can be taken. This allows y emitters to be more
reliably detected resulting in lower bias and uncertainty, and a lower rate of false negative
measurements due to non-homogeneity for y measurements. It may be advisable to consider
making standards for the gamma-screening equipment that are incident-specific in sample/
container size and in radionuclide(s) content.
Low-energy gamma emitters (with energy less than -40 keV) and those radionuclides decaying
via electron capture (followed by X-ray emission) will not be effectively identified by most
screening tests due to sample self-absorption. This issue may only come to light when
radionuclide-specific analyses have identified these low-energy emitters even when gross
activity screens do not indicate any activity. The final comparison between the screening result
and the sum of all radionuclide-specific activity concentration will show that the
alpha/beta/gamma screen has underestimated the activity concentration present in the sample.
In counterpoint to low-energy gamma-emitting radionuclides not contributing to the gross
activity concentration is the presence of varying degrees of NORM in soil samples. Uranium and
thorium decay products emit gamma rays and will contribute to the overall gross gamma activity.
Some short-lived radionuclides such as 212Pb and 212Bi may be present as unsupported progeny
of 220Rn (the thorium decay chain) and their activity will decrease rapidly between the time of
sampling and the time of counting. Other NORM progeny have long enough half-lives to be
present at the time of receipt of the laboratory and may be decaying during the screening process.
31
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
This means that gross radioactivity screening results for gamma and alpha or beta may change as
a function of time. For example, unsupported 224Ra progeny would decay with a half-life of
approximately 10 hours (based on the half-life of 212Pb).
Table 3 provides information about gamma rays that come from radionuclides not usually
determined by gamma spectrometry because their gamma ray abundances are relatively low. The
event that resulted in these radionuclides being deposited may have caused micron sized particles
to form with high specific activity concentration.21 These are referred to as discrete radioactive
particles (DRP) or "hot" particles. Thus an aliquant that contains a DRP could allow these less-
abundant radionuclide gamma rays identified in Table 3 to become a measureable feature in the
gamma ray spectrum. As such it is advisable to review spectra for the presence of these gamma
rays, or to add these radionuclides to the gamma spectrometry library. A longer count time for
this step than for the initial scan is appropriate if there are alpha or beta emitters with low
abundance gamma rays present. The staff can prepare sample aliquants for these analyses after
the soil dissolution steps are completed.
Table 3 - Radionuclides with Low-Abundance Gamma Rays Not Usually Used for
Analysis
Radionuclide
Principal Decay
Gamma, keV
Abundance, %
Radionuclide
Principal Decay
Gamma, keV
Abundance, %
Radionuclide
Principal Decay
Gamma, keV
Abundance, %
89Sr
£
909.0
9.56xKT3
232Th
a
911.2L2J
(338.3) [2],
from
228Ra/228Ac
25.8
(11.3)
240pu
a
45.2
(104.2,
160.3)
4.47 xKT2
(7.14xlO~3,
4.02 xlO~4)
90y
£
2186.2
1.4xlO~6
235U
A
143.8
(185.7 [3],
163.3)
11.0
(57.2, 5.08)
241Am
A
59.5
35.9
129j
£
39.6
(29.8 and
29.5 x-ray)[1]
7.51
(36.7 and
237Np
a
86.5
(311.9[2]from
233Pa)
12.4
(38.5)
241Pu
£
148.6
(103.7)
1.86xlO"4
(l.OlxlO"4)
21°Po
a
803.1
1.03 xlO~3
238U
a
100 1.0L2J from
(63.3[2]from
234Th)
0.842
(3.7)
242pu
A
44.9
(103.5,
158.8)
3.73 xl(T2
(2.55 xlO~3,
3.00xlO~4)
226Ra
a
186.2 [3]
(262.3) [1]
3.59
(5.0xlO~3)[1]
238pu
a
152.7
(43.5)
9.29xlO~4
(3.92xlO~2)
243Cm
a
277.6
(228.2,
209.8)
14.0
(10.6, 3.29)
228^
a
84.4
(131.6)
1.22
(0.130)
239Pu
a
51.6
(129.3,
375.1,
413.7)
2.72xlO~2
(6.31xlO~3,
1.55xlO"3,
1.47xlO"3)
Notes:
[1] Values in parentheses represent the next most abundant gamma ray.
21 Any radionuclide can form a DRP. However the significance of an alpha or beta emitter with a low abundance
gamma ray emission forming a DRP is that the radionuclide will be concentrated rather than spread out creating the
possibility of identifying these low abundance gamma rays in the spectrum.
32
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
[2] Based on activity of the progeny. Can only be used for quantification when the parent and progeny are
undisturbed for 5-10 progeny half-lives and they are known to be in secular equilibrium. For 237Np (by 233U) and
238U (by 234Th/234mPa) this requires about 4-9 months. For 232Th (by 228Ra) it requires 30-60 years and generally
applies only to undisturbed geological materials. Although these photopeaks cannot be used for quantification,
their presence in the spectrum provides valuable evidence and may confirm the presence of the radionuclide in a
sample.
[3] Note that the 186.2 keV photopeak from 226Ra cannot be resolved from the 185.7 keV photopeak of 235U. Unless
the interference can be resolved, or is determined to be trivial, these photopeaks should not be used for
quantification. Their presence in the spectrum, however, provides valuable evidence and may confirm the
presence of the radionuclide in a sample. Also, in samples with high 137Cs activity, the 661 keV backscatter peak
may be detected at 186 keV and could be mistaken for either 226Ra or 235U.
Additionally, certain a- and p-emitting radionuclides have very low-abundance y rays. These y
rays are not normally used for analysis of those radionuclides, and may not necessarily be
identified in gamma spectrometry software. Thus, if sufficient amounts of the radionuclides
noted in Table 3 are present in a soil sample, the alpha or beta measurement may not be
commensurate with the gross screen for gamma radiation.
However, as the activity concentration of these radionuclides decreases, it is a combination of y
ray abundance and half-life that makes the gamma ray of little utility at these lower-activity
concentrations. It is recommended that a separate library for incident response samples be
created that has these low-abundance y rays for radionuclide specific analyses. Table 3 provides
some examples.
These y rays can be used for qualitative identification of these radionuclides. Their presence in
the y-ray spectrum should direct the analyst to perform chemical separations followed by alpha-
or beta-specific detection.
Aluminum absorbers can be used to qualitatively identify the presence of radionuclides based on
penetrating ability. Thus, if an aluminum absorber of 6.5 mg/cm2 is used, and the measured
activity concentration is reduced to background, one could qualitatively state that the beta
particle energy of the radionuclide is < 0.067 MeV. Conversely, if the absorber has little effect
on the count rate, it can be stated that the beta particle energy is >0.067 MeV. Table 4 identifies
some beta-only emitters with their energies and range in aluminum absorbers.
Table 4 - Beta-Only Emitters
Radionuclide 241Pu 63Ni 129I 35S 99Tc 32P 90Sr/90Y
Maximum Beta Energy, MeV
Range [2], mg/cm2 for Epmax
0.021
0.8
0.067
6.5
0.150
27
0.167
32
0.294
75
1.711
800
(0.546)72.28 [1]
1,100
Notes:
[1] It may be assumed that 90Sr/90Y will be in secular equilibrium by the time any analysis is started. Thus, the 2.28
MeV beta particle of 90Y will be present.
[2] U.S. Department of Health, Education and Welfare (HEW). 1970. Radiological Health Handbook, p.123.
33
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
V. RADIOANALYTICAL SCENARIO 2 (IDENTIFYING UN CONTAMINATED SOIL
DISTANT FROM THE ROD SITE OR FOLLOWING INITIAL REMEDIATION)
1. Shipping and
sample container
exteriors screened
for a, p, y
3 .Coning/quartering
4a. Dry, pulverize, and
homogenize for non-
volatile analyses. Aliquant
for gross alpha beta screen
Non-volatiles
la. Sample is
screened for
Gross a p & Y
less than limiting
5a. Aliquant
for volatiles
analyses.
.^yearKHADLsin
Tables 7 A /7B
suits < limiting
1st year 1(H
ADLs
5b. Leach, low-
temperature
digestion or basic
fusion
4c. Aliquant and
perform fusion,
acid digestion, or
leach.
13. Archive
sample until
high priority
samples are
analyzed
6.
HPGe
analysis for
y emitters
7b.
Analyses for
emitters
7a.
Analyses for
a emitters
ult for x
dionuclide
> limiting 1st year
KHADL Table
1C or7D
Review and validate results.
Key
Highest priority
Second priority
Isotopic
results agree
with screen
results
SOF
Complete
report
See accompanying tables
for alpha and beta/gamma
concentrations, and
numbered notes
Figure 4 - Radioanalytical Scenario 2 (Identifying Samples with Activities less than KH Risk - First Year)
34
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Notes for Scenario 2: Several weeks to months following the initial event. Radionuclide
contaminants are known.
Purpose: Identify areas where contamination has not occurred, or areas that have
been successfully remediated.
The samples may arrive over several days. It is likely that detailed screening of samples at this point
will not provide any significant insight into the radionuclide content of the samples because the AALs
identified in Tables 7A and 7B for first year exposure at 1CT4 risk will yield screening values close to
background for normal soils (these may well be above the ADL in these tables). If volatile
radionuclides such as 1251,1291,1311,99Tc, or 3H are expected to be part of the sample matrix, an alternate,
parallel sample processing path specifically for these volatile radionuclides is performed. Only after an
analytical step or procedure has been completed for the highest priority samples should lower-priority
samples be addressed. Lower-priority samples (yellow on this chart) may need to be stored for several
days until the highest priority samples have been analyzed. The samples with the highest priority in this
instance will be the ones with the lowest activity concentration.
The radionuclide activities corresponding to PAG values for this scenario assumes a first year exposure
and can be found in Tables 7A and 7B for screening and 7C and 7D for radionuclide-specific activities.
The exterior surfaces of the containers are swiped to determine if any contamination is
present. The actions taken and the limits for those actions should be established by the
individual laboratory according to their radiation safety manual.
These might include a Geiger-Mueller counter with appropriately calibrated beta and
gamma detector probes or a micro-roentgen meter (gamma only).22 This step should be
performed with the sample container unopened. Surface swipes of the container are taken
to assess the presence of external gross a/P and y contamination. These surveys are for
contamination control purposes and not for the assessment of sample processing flow
path.
Any container with measurable external contamination should be decontaminated before
proceeding with subsequent analysis. This will help to minimize sample cross-contamina-
tion as well as laboratory contamination.
Gamma Screening
An initial screen is performed by directly counting the unopened sample container for a
short count time on a HPGe detector.23 MQOs required method uncertainty and ADLs for
the 1CT4 risk level are used (see Table 7B for screening measurements of beta emitters).
Some laboratories may use a Nal(Tl) detector to determine whether the gross y activity
indicates that the activity of gamma emitters in a sample is less than an AAL
Some manufacturers have developed kits that include the survey meter plus an alpha-beta-gamma pancake GM
detector and a Nal gamma detector.
23 The potential configurations for these measurements are outlined in Radiological Laboratory Sample Screening
Analysis Guide for Incidents of National Significance (EPA 2009b).
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
concentration. The survey instrument should be calibrated for the geometry used and for
the gamma-emitting radionuclide of concern having the limiting AAL listed in Table 7B.
In order for gamma measurements to be used to quickly assess whether sample activity
will be less than first year 10 4 risk A^
radionuclides are present in the sample.
will be less than first year 10 4 risk AALs, it must be known that only gamma-emitting
It may not be possible to determine some gamma-emitting radionuclides with low enough
uncertainty at the AAL concentration to meet MQOs when the sensitivity of the
instrument used is inadequate, or for very low-abundance or low-energy gamma emitters.
Radionuclides that do not emit y- or X-rays greater than 40 keV, including pure alpha and
beta emitters such as 210Po or 90Sr, will not be detected.
Gross Alpha and Beta
NOTE: The techniques described here present a rapid, positive approach to screening of soils.
They involve digestion and aliquanting methods commonly used in the radiochemistry
laboratory and require open handling and processing of samples that may contain elevated
levels of radioactivity. Laboratory staff need to take specific precautions while performing
these techniques to avoid personal contamination (including inhalation), laboratory surface
contamination, and sample cross-contamination especially since the radioactivity level of pure
alpha or beta emitters in the sample is initially unknown. Additional precautions should be
taken to dedicate a segregated area for screening samples.
The samples received from a radiological incident may come in a variety of containers:
plastic bags, plastic bottles, glass bottles, Petri-style containers, aluminum cans, etc. The
masses of the samples received also will vary significantly. If possible, using several
different style containers with different masses of standards for use in calibration of
screening equipment will be helpful in minimizing the time for the initial sample
screening process.
Screening of the sample for a and P activity must be done carefully as the gamma screen
may not yield any indications of elevated activity concentration when only pure alpha- or
beta-emitting radionuclides, or radionuclides that only emit y or x-rays below the
calibrated range of the instrument. A very rudimentary screening process, performed in a
hood, should be used prior to removing the entire sample from its container for
homogenization and sub-sampling. Some options for making such a measurement may
be:
• Take a swipe of the inside of the container cap. Then, using an alpha-beta probe,
determine the count rate of the swipe.
• Insert a tongue depressor (with double-sided tape on one surface) into the container
and remove for direct measurement.
• Take a small aliquant of the top surface (after the sample container is shaken) and
spread it onto a planchet.
36
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
• Take a measured aliquant and place it into a scintillation vial with cocktail for liquid
scintillation analysis.
• Perform a rapid nitric-hydrofluoric acid digest (total dissolution is not necessary) on a
small aliquant of the sample and evaporate onto a planchet.
For the first three bullets above, an initial estimate of the mass transferred using the
specific technique should be made with a soil of similar composition. The probe used for
such techniques should have been calibrated with soil samples spiked to a level
simulating the AAL values.
The last two options above, LSC and GPC provide more quantitative measures of gross
alpha/beta activity. LSC can provide a faster screening process and avoid some of the
shortcomings of a sample leaching process needed for GPC because the effects of self-
absorption in the sample test source are minimized using LSC. The procedure used must
correct quench from various sources in the soil, and the method must be validated prior to
use on samples from an incident. It may be impractical to separate alpha from beta
signals using pulse-shape analysis when high levels of quench are present. Quench will
shorten the duration of alpha pulses making them appear more like a beta pulses. Instead,
a total activity measurement (combined alpha and beta) across the entire energy spectrum
may provide the most reliable estimate of activity in highly quenched sample.
For soil samples, the question arises of how to introduce the solid sample into the liquid
scintillation matrix. Although there are no standard methods that specifically address this
issue, several general approaches are commonly used. The first, perhaps more
conventional approach, involves direct measurement of the solid. The second involves
leaching or digesting a representative aliquant of the solid sample and processing the
leachate / digestate as if it were an aqueous sample. The third approach involves directly
suspending a small, representative aliquant of the soil in a gelling liquid scintillation
cocktail.24
The limiting factor in using gross alpha beta measurements for reliable decisionmaking is
obtaining a representative aliquant. In contrast to the gamma measurement where the
entire sample is measured, the relatively small portion of unhomogenized sample may not
be representative of the entire sample. The small aliquant may indeed completely fail to
identify non-homogenously distributed activity present in a sample. The alpha / beta
screen may still provide important information with regard to handling and indicate a
need for personal protective measures since the next steps involve working with the
entire sample in unencapsulated form.
While gamma measurements may meet MQOs prior to complete homogenization of the
sample, high levels of uncertainty associated with the alpha beta screening techniques
discussed above, however, may preclude use of those results for making reliable
decisions until a representative aliquant can be obtained following homogenization of the
24 Cocktails such as Insta-Gel, or Quicksafe A may be used since they will suspend the solid and allow it to be
counted in a 4-jc geometry.
37
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
sample. It is important to ensure that estimates of the measurement uncertainty are robust,
and that MQOs for uncertainty have been met before using data to decide that a sample
concentration exceeds an AAL. If estimates of uncertainty are deemed to be unreliable,
the results should not be used for critical decisionmaking. Thus it may be necessary to
delay decisions about whether AALs for non-gamma-emitting radionuclides have been
exceeded until the sample is milled and homogenized and a representative aliquant can be
obtained.
Any of the above techniques will yield a good estimate of the potential a and P activity
concentration of the sample. If pure alpha or beta emitters may be present, or if the gross
gamma result is less than the limiting ADL at the 10~4 risk level , or if the MQOs for
required method uncertainty cannot be met, proceed with coning, quartering and
homogenization to obtain a representative aliquant of the sample.
If only gamma emitters are present, and the gamma screening performed in Ib satisfies
the MQOs for required method uncertainty, and the gross y activity is less than the
limiting ADL listed in Table 7B, the 1C may be notified that no AALs are exceeded and
the sample may be archived.
A process described as "coning and quartering" is used to break the entire bulk sample
down into representative subsamples. Unless the project has a specific MQO stating the
contrary, remove extraneous detritus (e.g., sticks, twigs, rocks larger than 1/4", etc.). The
removed material should be retained for potential future analysis and an appropriate
comment added to the case narrative.
Fractions are isolated for volatile radionuclides and gamma spectral analysis, and for
analysis of non-volatile radionuclides, where required. The volatile fraction should be
processed quickly and immediately sealed in containers to minimize potential losses of
volatile radionuclides.
This process is described in the Appendix to Rapid Method for Fusion of Soil and Soil-
Related Matrices Prior to Americium, Plutonium, and Uranium Analyses; Rapid Method
for Radium-226 Analyses in Soil Incorporating the Fusion of Soil and Soil-Related
Matrices; and Rapid Method for Sodium Carbonate Fusion of Soil and Soil Related
Matrices Prior to Strontium-90 Analysis (EPA 2012a).
Precautions should still be taken (e.g., opening the sample container and handling in a
hood) since the alpha/beta activity concentration has only been assessed by bulk
screening techniques which may have very high uncertainties.
Steps 4 through 7 may be performed concurrently.
After the coning and quartering, place the sample in a tared can (without lid) and dry the
soil to constant weight in an oven at 110 ±10 °C. Drying samples provide for consistent
38
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
comparison of results regardless of moisture content.
Note: Constant weight may be determined by removing the container from the oven
and weighing repeatedly until the mass remains constant to with within 1%. This also
may be achieved operationally by observing the time needed to ensure that 99% of all
samples will obtain constant weight.
This is the dry-weight basis for the analysis. This mass is also used to calculate the
fractional solids content for each sample (i.e., percent solids) so that results from the
volatile fraction, analyzed "as received" can be converted to and reported on a dry-weight
basis.
Once the sample is dried, homogenization continues using the same vessel (the paint
can). Stainless-steel or ceramic balls or rods are added to the can and the can is shaken
for about 5 minutes, or as needed to produce a finely-milled, well-homogenized, sample.
The precise particle size of the milled sample is not critical as long as the milled sample
is fine enough to facilitate a rapid and complete dissolution of the soil matrix.
NOTE: A qualitative, visual standard can be prepared by passing quartz sand or other milled
material through a 50-mesh and then a 100-mesh screen. The portion of the sample retained in
the 100 mesh screen can be used as a qualitative visual standard to determine if samples have
been adequately pulverized. The process is complete once 95% of the sample (or greater) is as
fine, or finer, than the qualitative standard. If, by visual estimation, more than ~5% of total
volume of the particles in the sample appear to be larger than the particle size in the standard,
return the sample to the shaker and continue milling until the process is complete.
If visual inspection of the milled sample shows elevated presence of larger particles that
may not be effectively dissolved during the fusion or digestion process, the sample
should either be milled for a longer period of time, or those particles preferentially
removed prior to aliquanting. In most cases, preferential removal of a small fraction of
larger particles will still provide representative results since the surface area of larger
particles is relatively low, and that surface will be abraded during milling, and the activity
associated with sample fines should be representative of that found in the original sample.
A comment should be added to the sample narrative addressing removal of the solids.
NOTE: In this scenario, the radionuclides that are potential contaminants are known. This may
mean that if a single type of emitter is present that the ADL for that specific radionuclide
should be used. However, when mixed decay modes are present, it may be necessary to
compare alpha, beta, or gamma emitting radionuclide screening results based on gross gamma
or combined gross (a + (3).
Prior to aliquanting samples in Step 4c, the sample is screened for gross alpha and beta. A
stainless steel planchet to which an adhesive backed cloth swipe has been applied is
tared, and a small aliquant of dried, pulverized solid (e.g., <0.1 gram) is transferred to the
upward-facing textured surface of the swipe. Using a hand-held survey meter, the
planchet is screened to detect the presence of elevated alpha and beta activity that would
39
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
be a concern to handling outside the hood and could result in contamination of the low-
background proportional counter. The planchet, swipe, and solid are reweighed to
determine the net amount of sample on the planchet. The residues are fixed to the
planchet by applying a very light layer of hair spray. The planchet is dried for a minute
under a heat lamp and reweighed to determine the final mass to use for self-absorption
corrections for the gross alpha and beta measurement. The sample test sources are
counted on a gas flow proportional counter to determine the gross alpha and beta activity.
Prior to, or concurrent with, Step 5a, soil samples with significant organic content should
be ashed to completely combust organic matter. This can be accomplished using a
programmable furnace where a temperature of approximately 600 °C can be achieved.
Ramping up the temperature in time intervals is necessary to avoid uncontrolled ignition
and excessive smoke generation during the process. If the sample is ashed prior to
aliquanting, it is important to record the wet, dry, and combusted masses so that the
wet/dry ratio (i.e., percent solids) (and the percent organic content if required) can be
calculated and used to convert final results to a dry-weight basis
The results of the alpha/beta screen are reviewed to determine whether any limiting
ADLs have been exceeded. If the MQO for required method uncertainty for alpha
screening is met, and the gross alpha concentration is less than the lowest applicable 10"4
ADL in Table 7 A, the sample will be analyzed for a-emitting radionuclides using
radionuclide-specific methods.
If the MQO for the required method uncertainty for gross beta screening is met, and the
beta concentration is less than the lowest applicable 10"4 ADL in Table 7B, the sample
will be analyzed for radionuclide-specific 3-emitting radionuclides. If more than one
radionuclide is of concern, or if a screening technique is used that provides an aggregate
value for the radioactivity (i.e., it does not differentiate between alpha and beta but
reflects their summed total), and the activity is less than the lowest applicable 10"4 ADL
in Tables 7A or 7B, the sample will be analyzed for all applicable radionuclide-specific
alpha-only and beta-only emitters.
The screen also will provide the most reliable information yet on levels of activity that
are present. This can be used to determined appropriate levels of contamination control
and personal protective gear needed. The results may also be used to determine whether
tracer levels should be adjusted when aliquant size cannot be reduced due to concerns
about the representativeness of the sample (e.g., 0.5-1 gram).
4C Individual non-volatile radionuclides (with the exception of gamma emitters) are
prepared for analysis using validated techniques for dissolution and chemical separation.
Separate aliquants may be removed for radionuclide-specific analysis for non-volatile
components. Aliquant size should be coordinated with planned count times to ensure that
the required method uncertainty will be met, and to optimize throughput. The dried
samples are dissolved so they may be aliquanted for analysis of remaining potential
radionuclides appropriate to the radionuclide analyses to be performed.
40
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
For samples resulting from an RDD, it is important to ensure complete dissolution of
potentially refractory materials. Certain materials such as those used in a radioisotope
thermoelectric generator (RTG), brachytherapy sources, or radionuclides that have been
exposed to a high temperature detonation may be difficult to dissolve using conventional
acid digestion techniques.
Sodium carbonate or sodium hydroxide fusions are two good methods for complete
dissolution of soil samples. It is important to achieve complete dissolution as refractory
materials could result from an RDD, which would not be dissolved by simple acid
dissolution. Fusions help ensure isotopic exchange of analyte with the tracer or carrier in
the homogeneous melt formed. Soil dissolutions using hydrofluoric acid (FTP) may not
effectively solubilize certain refractory materials, but they can be very effective in
completely dissolving a variety of matrices including poorly soluble silica-based
materials.
Representative portions of the "as received" (i.e., undried) sample are aliquanted as
needed for FIPGe gamma analysis, and where required, for analysis of volatile
radionuclides. The sample should be mixed, homogenized, and subsampled rapidly and in
a manner that minimizes loss of volatiles while ensuring that aliquants will be
representative of the original sample.
Analyses for volatile radionuclides should be started as soon as possible to minimize loss
of analyte. If sample analysis cannot be started immediately, a project-specific means of
sample storage for volatiles should be in place so that even short-term storage does not
significantly reduce their concentration. Volatile radionuclides are prepared for chemical
separations using validated dissolution techniques that will prevent loss of analyte due to
volatilization. These processes should be performed in a manner that also minimizes loss
of volatiles. Low temperature digestion, basic leach, or basic fusion techniques,
combined with appropriate oxidation/reduction control are used to create one or several
stock solutions while ensuring that radionuclides are in non-volatile form.
Note that all analysis results from the volatile fraction should be calculated and reported
on a dry-weight basis. For example, the volatile fraction can be analyzed "as received"
and the results converted to dry-weight basis by applying the percent solids value
determined in Step 4a.
Gamma spectrometric analysis is performed on the undried fraction isolated in Step 4b
using a HPGe gamma detector. Aliquant size and count times should be optimized to
ensure that the required method uncertainty is met, and to optimize throughput. Since an
"as received" sample is counted, results are calculated and reported by applying percent
solids values determined in Step 4a.
The volumetric configuration and density of the sample should be as close as possible to
the calibration standard. Every soil sample will have some naturally-occurring
radionuclides present. A sample with similar soil composition from a representative non-
41
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
impacted area may help in determining the radionuclide concentration levels of
background radionuclides in uncontaminated soil.
The sample needs to be counted long enough to achieve the respective MQO for the
required method uncertainty indicated in Table 7D. For example, if 60Co were the
radionuclide of concern, a required method uncertainty of 2.5 pCi/g would be required at
the AAL of 20 pCi/g. The final result would be compared to the predicted ADL for 60Co
of 14 pCi/g.
If gross alpha or beta concentrations are less than their respective ADLs, chemical
separations should be started immediately using validated procedures for each alpha or
beta emitter to be determined. Sample test sources should be counted such that the
measurement quality objectives for the event will be met. If the project manager does not
specify the sequence of analyses, laboratory personnel should use their best professional
judgment, based on the characteristics of the samples, to determine the order of
processing the samples so that the results are obtained in the timeliest manner.
Analytical results should be collected for each sample (both the screening values on the
raw sample and the final radiochemical-specific analyses). The results should be
reviewed and reported by knowledgeable personnel (per the laboratory's QA program).
As reviews are completed, and finalized radionuclide-specific results become available,
each individual result is compared to project-specific MQOs and ADL values (see Tables
7C or 7D for default values). For example, for the 10~4 risk PAG in Table 7C, the
required method uncertainty for 241Am is 8.2 pCi/g at the AAL of 65 pCi/g and the ADL
of 46 pCi/g. If the MQO for required method uncertainty is met, and the activity
concentration exceeds the ADL, the 10~4 risk AAL has been exceeded. The 1C should be
promptly notified (broken line to Step 11). If any AAL is shown to be exceeded, proceed
with archiving sample residuals, digests and sample test sources in Step 13 and transfer
available resources to the continued analysis of potentially uncontaminated samples.
Compare the sum of all final analytical results that are above their respective critical level
concentrations with the sum of the respective gross radioactivity measurements. This is
done to verify that no major radionuclide contributor to dose has been missed. Isotopic
and gross screening results should agree with each other within a factor of about two.
Discrepancies in agreement may indicate that a major radionuclide may have been
omitted from the analysis sequence in Steps 6, 7a, or 7b, or they may be attributable to
problems with the analytical process. They may also indicate that the screening process
needs to be adjusted based on the specific radionuclides identified in the samples.
Comparability may not be realized for volatile radionuclides, when radionuclides with
low-energy emissions (beta-gamma, conversion electrons, x-rays, etc.) are present.
Difference may also result when radionuclides with short-lived decay progeny are in the
mix of radionuclides in the sample. For example, if 103Ru is detected by gamma-ray
spectrometry, its progeny 103Rh may not be specifically identified by the software, even
42
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
though it is present in secular equilibrium within hours. Significant unreconciled
differences between the screening and the summed radionuclide-specific results should
be noted in the report to the 1C.
If the screening process indicated <10 4 risk whereas radioanalytical results show >10 4
risk, consider whether the screening process may not be sufficiently robust at the 10^ and
1CT6 risk levels to identify low activity concentrations for the radionuclides present.
Calculate the sum of fractions at this point. The calculation of the sum of fractions
follows the following equation:
= Yf-?t
Sum of Fractions
Where R; is the activity of the individual radionuclide and AAL; is the analytical action
level of that radionuclide for the 1CT4 risk level at one year of exposure.
If the sum of fractions is > 1.0 then the AAL for 10 4 risk level for the first year exposure
may have been exceeded.
The dashed line connecting Box 9 with Box 12 indicates that that checking SOF may not
always be needed.
Contact the 1C with the results of the analysis, in this case indicating whether the results
confirm that the radionuclides present pose <10 4 risk based on the radionuclide activity
concentrations identified.
Sample residuals, unused dissolved sample, and sample test sources should be archived if
potential analysis is needed at a future date.
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
VI. RADIOANALYTICAL SCENARIO 3 (IDENTIFYING SOIL CONTAMINATED WITH
FISSION PRODUCTS FOLLOWING AN IND INCIDENT)
II. Sampleis
screened using
beta-gamma
instrument
Sample screeningVYes
Key
| | Highest priority
I I Second priority
I I End result
See accompanying tables
foralpha and beta/gamma
concentrations, and
numbered notes
5. Fusion or acid
dissolution
4. Dr}
homogenize, am
Volatiles
6. Homogenize and
aliquant for gamma and
volatiles.
.HPGe
analysis
10. Leach, low-
temp erature digestion
or basic fusion
Gross alpha
1. Analyze sampl
for volatiles
8b.
Gross alpha
screen
9,100 pCi/
13. Assess data
against screen,
backgrounder
reference result
1
Indivi
result > 1,000
mrem AAL
orSOF>l
17. Archive
STS, samples,
and residuals
for potential
future analysis
Figure 5 - Radioanalytical Scenario 3 (Samples Resulting from an IND)
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Notes for Scenario 3: An IND has been detonated. It is within the first week of the incident.
Purpose: Identify principal fission and activation products and their
concentrations in samples with the highest activity.
Samples will arrive and will require rapid screening to identify the most highly contaminated first. The
majority of the fission products will be gamma emitters. The principal volatile species present will be
tritium, iodine, and xenon isotopes. The iodines and xenons are all gamma emitters. The principal U
and transuranic isotopes of concern will be 234U, 235U, 238U and 239/240pu from the original nuclear
material and some neutron-capture progeny of each of these isotopes.
The radionuclide activities corresponding to early phase 1,000 mrem PAG values for this scenario can
be found in Tables 6A and 6B for screening and 6C and 6D for radionuclide-specific activities.
An IND probably will have a lower explosive yield than a military nuclear weapon. This
will mean that not only will there be fission products dispersed, but also dispersal of
material that has either not undergone fission or fissionable material that has undergone
activation instead of fission. Table 2 lists radionuclides resulting from a fission event
(half-lives greater than ~ Iday). Table 9 lists several short-lived radionuclides that may be
present in the first days following an IND. There is some overlap between the tables.
These radionuclides, as well as other principal fission products, are beta/gamma emitters
and will be able to provide a good response to screening on a beta/gamma survey
instrument at the 1,000-mrem PAG concentration (Early Phase) and the 2,000-mrem PAG
(first year) identified in Table lOa. This could be a Geiger-Mueller type device or a
handheld Micro-R meter. The radionuclide that has the lowest PAG value is 60Co.
Although 60Co is not a fission product, it may be formed as a result of neutron activation
of stable 59Co, a trace element in steel and other building materials. Initial calibration of
screening instruments with this radionuclide would be acceptable until more specific
information is known about the sample composition.
It is very likely that IND material that did not fission will have fission products associated
with it. Since all fission products are beta or gamma emitters, the sample may be screened
by measurement of its gamma emissions. The measurement should meet the Early Phase
1,000-mrem Early Phase PAG MQO for required method uncertainty for 60Co (3,900
pCi/g at the AAL of 13,000 pCi/g) shown in Table 10A.
If the gross gamma activity concentration exceeds the ADL for 60Co of 6,500 pCi/g,
proceed with additional radionuclide-specific analyses. If radionuclide-specific gamma
analysis is performed using a HPGe spectrometer, MQOs are satisfied and any
radionuclide exceeds the respective 1,000-mrem PAG radionuclide-specific ADLs
identified in Table 10B, proceed with additional radionuclide-specific analyses. Otherwise
archive the sample for potential future analysis per Step 17. Report analysis results to the
1C and indicate that measurements show sample activity below the 1,000 mrem Early
Phase PAG AAL values.
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
The entire sample should be coned and quartered to break the bulk sample down into
representative subsamples. Unless the data quality objectives for the project state the
contrary, remove detritus (e.g., sticks, twigs, rocks larger than 1/4", etc.) prior to coning
and quartering. Save the removed material for potential future analysis and make an
appropriate note of this in the case narrative.
Fractions are isolated for volatile radionuclides and gamma spectral analysis, and for
analysis of non-volatile radionuclides. The volatile and gamma fraction should be
processed quickly and immediately sealed in containers to minimize potential losses of
volatile radionuclides.25
Steps 4 through 8 may be performed concurrently.
Transfer the non-volatile fraction isolated in Step 3 to either a 1-pint or 1-quart paint can
(depending upon the sample size). Place the can (without lid) in an oven at 110±10 °C and
dry the soil to constant weight. Drying samples provide for consistent comparison of
results regardless of moisture content.
Note: Constant weight may be determined by removing the container from the oven and
weighing repeatedly until the mass remains constant within 1%. This also may be achieved
operationally by observing the time needed to ensure that 99% of all samples will obtain
constant weight.
This is the dry-weight basis for the analysis. This mass is also used to calculate the
fractional solids content for each sample (i.e., percent solids) so that results from the
volatile and gamma fractions, which are analyzed "as received," can be converted to and
reported on a dry-weight basis.
Once the sample is dried, homogenization continues using the same vessel (the paint can)
by adding stainless-steel or ceramic balls or rods to the can and shaking for about 5
minutes, or as needed to produce a finely-milled, well-homogenized, sample. The precise
particle size of the milled sample is not critical.
NOTE: A qualitative, visual standard can be prepared by passing quartz sand or other milled
material through a 50-mesh and then a 100-mesh screen. The portion of the sample retained in
the 100 mesh screen can be used as a qualitative visual standard to determine if samples have
been adequately pulverized. The process is complete once 95% of the sample (or greater) is as
fine, or finer, than the qualitative standard. If, by visual estimation, more than -5% of total
volume of the particles in the sample appear to be larger than the particle size in the standard,
return the sample to the shaker and continue milling until the process is complete.
This process is presented in detail in Rapid Method for Fusion of Soil and Soil-Related Matrices Prior to
Americium, Plutonium, and Uranium Analyses; Rapid Method for Radium-226 Analyses in Soil Incorporating the
Fusion of Soil and Soil-Related Matrices; and Rapid Method for Sodium Carbonate Fusion of Soil and Soil Related
Matrices Prior to Strontium-90 Analysis (EPA 2012a).
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
If, by visual inspection, the sample appears to contain larger particles that may not be
effectively dissolved during the fusion or digestion process, those particles may be
preferentially removed prior to aliquanting. In most cases, removal of a small fraction of
larger particles will still provide representative results since the surface area of larger
particles is relatively low, and that surface will be abraded during milling. As a result, the
activity associated with sample fines should be representative of that found in the original
sample. A comment should be added to the sample narrative addressing removal of the
solids.
A representative aliquant of the dried, homogenized sample is taken for gross alpha
screening and subjected to the same dissolution process used for radionuclide-specific
OQ
analyses. Separate aliquants are also removed for radionuclide-specific analysis of Sr
and 90Sr, and for potential alpha spectrometric analysis of Pu and U isotopes. Note that no
tracers/carriers should be added to the aliquant for gross alpha as these will interfere with
the determination of gross alpha activity.
Prior to or during Step 5, soil samples with significant organic content should be ashed to
completely combust organic matter. This can be accomplished using a programmable
furnace where a temperature of approximately 600 °C can be achieved. Ramping up the
temperature in time intervals is necessary to avoid uncontrolled ignition and excessive
smoke generation during the process. If the sample is ashed prior to aliquanting, it is
important to record the wet, dry, and combusted weights so that percent solids and the
percent organic content (if required) can be calculated and used to convert final results to
a dry-weight basis.
Aliquants of the dry sample from Step 4 are taken for total dissolution. For samples from
an IND, it is important to achieve complete dissolution of refractory materials prior to
chemical processing. Sodium carbonate or sodium hydroxide fusions offer two good
methods for complete dissolution of soil samples. Fusions help ensure isotopic exchange
of analyte with the tracer or carrier in the homogeneous melt formed. Soil dissolutions
using hydrofluoric acid (HF) may not effectively solubilize certain refractory materials,
but they can be very effective in completely dissolving a variety of matrices including
poorly soluble silica-based materials.
A clear melt of the sample, or a clear solution from acid digestion should be achieved. If
the dissolution process does not completely dissolve the sample, undissolved material
potentially should be set aside for additional analysis and an appropriate note made in the
case narrative.
The "as-received" sample fraction isolated for gamma and volatile radionuclides in Step
3 should be mixed, homogenized, and subsampled rapidly and in a manner that
minimizes loss of volatiles while ensuring that aliquants will be representative of the
original sample. In addition, if radionuclides are present in organic compounds, aliquants
may be removed for separate analysis.
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Representative portions of the "as received" fraction are aliquanted as needed for HPGe
gamma analysis, and for radionuclide-specific analysis of volatile radionuclides such as
O I fJQ QQ
H, I or Tc. Aliquant size should be planned to optimize count times and throughput
while ensuring that MQOs for required method uncertainty are met.
Analysis for short-lived species or volatile radionuclides, such as 131I and noble gases,
should begin as soon as possible to minimize decay and optimize count times, and to
minimize losses due to volatility of the analytes. If analysis for volatiles cannot be started
immediately, a project-specific means of sample storage for volatiles should be in place
so that even short-term storage does not significantly reduce their concentration.
An aliquant of the sample from Step 6 is taken and counted using an HPGe detector.
HPGe analysis is performed on the "as-received" fraction of sample isolated in Step 3.
Analysis of the volatile fraction will produce results that are valid for all gamma emitters,
volatile or non-volatile.
The volumetric configuration and density of the sample should be as close as possible to
the calibration standard. Every soil sample will have some naturally-occurring
radionuclides present. A sample with similar soil composition from a representative non-
impacted area may help in determining the radionuclide concentration levels of
background radionuclides in uncontaminated soil.
The sample needs to be counted long enough to measure the AAL concentration of 9,200
pCi/g of 60Co with a required method uncertainty of 1,600 pCi/g. Note that 60Co is the
gamma emitting radionuclide with the limiting activity concentration for 1,000-mrem
PAGinTablelOB.
The product of the dissolution from Step 5 is dissolved in acid and the sample screened
for gross alpha to assess if alpha-specific analyses should be done. The sample should be
counted long enough to meet an MQO for required method uncertainty for 239Pu of 410
pCi/g at the AAL of 1,300 pCi/g. (Note that 239Pu is the alpha emitting radionuclide with
the limiting activity concentration for 1,000-mrem PAG in Table 6A.)
If liquid scintillation screening is used, alpha / beta discrimination can be used to
significantly reduce interference from beta emitters. The pulse-shape discriminator is
pushed past the classic cross-over point used for simultaneous counting of alpha and beta
to a point where beta-to-alpha crosstalk is nearly eliminated. Additional information may
be available from the gamma spectrometry analysis performed in Step 7 as there are
several gamma lines from either U or Pu fissile materials that will give an indication of
the presence of these materials.
P Results of the gross alpha screen are compared to the ADL of 9,100 pCi/g (1,000-mrem
PAG in Table 6A). If the alpha screening ADL is exceeded, analysis for uranium and
plutonium isotopes is performed using a rapid method such as the Rapid Radiochemical
Method for Selected Radionuclides in Water for Environmental Restoration Following
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Homeland Security Events (EPA 2010). MQOs and ADLs for the 1,000-mrem PAG are
stated in Table 6A.)
If gamma-specific analysis in Step 7 indicates the presence of fission products, then
analysis for 89Sr and 9 Sr should be started immediately as they are principal fission
products and neither is a gamma ray emitter. The product of the dissolution of the dried
sample from Step 5 is dissolved in acid and analyzed for radiostrontium. The sample may
be initially analyzed for total radiostrontium. The analysis should be configured to meet
the MQO for required method uncertainty at the 1,000 mrem level in Table 10B (2.7xl04
pCi/g at an AAL of 2.1><105 pCi/g). If radiostrontium activity is detected, above the ADL
of 150,000 pCi/g, 89Sr and 90Sr should be speciated and compared to their respective
ADLs.
Volatile radionuclides are prepared for chemical separations from the aliquants in Step 6
using validated dissolution techniques that will prevent loss of analyte due to
volatilization. These processes should be performed in a manner that also minimizes loss
of volatiles. Low temperature digestion, basic leach, or basic fusion techniques, combined
with appropriate oxidation/reduction control are used to create one or several stock
solutions while ensuring that radionuclides are in non-volatile form.
Note that all analysis results from the volatile fraction should be calculated and reported
on a dry-weight basis. For example, the volatile fraction can be analyzed "as received" and
the results converted to dry-weight basis by applying the percent solids value determined
in Step 4a.
Chemical separations should be started immediately using validated procedures for each
volatile alpha or beta emitter to be performed. Sample test sources should be counted such
that the measurement quality objectives for the 1,000 mrem PAG in Tables 6C and 10B
will be met. If the 1C does not specify the sequence of analyses, laboratory personnel
should use their best professional judgment, based on the characteristics of the samples, to
determine the order of processing the samples so that the results are obtained in the
timeliest manner.
When all analyses are completed, validate the individual results and determine if all
information requested has been finalized.
Review the screening and analytical process to assess where there may be a discrepancy
between the screening process that indicated < 1,000 mrem (short-term exposure PAG)
and the radioanalytical results that indicate > 1,000 mrem.
If the results of screening and background measurements compared with the sample
activity are in reasonable correspondence, proceed with Step 1. If not re-review the
analytical results prior to proceeding.
49
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
The final results for each sample are compared to project-specific criteria. Each individual
radionuclide analyzed will be compared to its ADL value cited in Table 6C or 10B. Also
calculate the sum of fractions using the following equation:
11
Sum of Fractions = y
[AAU
Where R; is the activity of the individual radionuclide and AALt is the analytical action
level of that radionuclide for the 1,000-mrem PAG at one year of exposure.
If the sum of fractions is > 1.0 then the 1,000-mrem PAG for short-term exposure has
been exceeded. This means that there may be discrepancy between the screening and the
final results, or that the screening process may need to be adjusted based on the specific
radionuclides identified in these samples.
Contact the 1C with the results of the analysis, in this case indicating that these results
confirm that the radionuclides present are greater than the 1,000-mrem PAG based on the
radionuclide activity concentration identified.
Sample aliquants and unused dissolved fusion melts should be archived for analysis at a
future date if needed.
50
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Additional Points for Scenario 3
Gamma Ray Analysis
The detonation of an IND will create many fission products that decay in mass chains by
P7gamma emission. The heads of each mass chain are generally very short-lived (seconds to
hours) and sampling of soil following such an event would not identify any of these "heads-of-
chain." However, several fission products form parent-progeny pairs that establish radiochemical
equilibria after the event over the course of days to months. Some of the pairs that form these
equilibria are identified in Table 5. Some pairs that are specifically not noted in this table are
those that form secular equilibria with their progeny in time frames that are very short. Examples
of these are 137Cs-137Ba (equilibrium achieved in -10 min), and ^Ru-1 6Rh (equilibrium
achieved in ~4 min).
Table 5 - Time for Certain Radionuclide Pairs to Achieve Maximum Progeny Activity
Radionuclide
Pair
Ba-140/La-140
Zr-95/Nb-95
Te-132/I-132
I-131/Xe-131m
Nd-147/Pm-147
Ce-143/Pr-143
A, Parent
(Days)
5.435xlO'2
1.082X10'2
2.166X10'1
8.641xlO'2
6.31 lxlO~2
5.033XKT1
A, Progeny
(Days)
4.130x10^
1.981xlO~2
7.295
5.824xlO~2
7.232xlO~4
5.107xlO'2
Time to
Peak Progeny
Activity
(Days) [1]
5.7
67.3
0.50
14.0
71.6
5.1
Type of
Equilibrium
Transient
Transient
Transient
No
No
No
Decay
Correction
(post
equilibrium)
A, Parent
A, Parent +
Equation
A, Parent
A, Progeny
+ Equation
A, Progeny
+ Equation
A, Progeny
[1] These times are calculated using the equation for the maximum number of progeny atoms, N2, to achieve
equilibrium:
Practical times to reach equilibrium (e.g., 99% of maximum) are shorter than those identified above.
When analyzing samples, if either member of the pair is present the other must have been present
(no equilibrium cases) or is still present (transient and secular equilibrium cases). For example if
140La is identified by gamma ray spectrometry, 140Ba must also be present as it is the longer-lived
progenitor of the 1 °La. Once the activity of each member of the radiochemical equilibrium is
identified, the decay correction to a point in time may need to be determined. For the
radionuclides identified in Table 5 (and those others with very short equilibration times), decay
correction either to the time of sampling or forward to a future date has several different cases
that need to be considered. These cases depend on the:
• Time that has passed from the time of the incident to the time of deposition,
• Chemical solubility differences of the pairs during the transport to the soil,
• Chemical solubility/transport in the soil matrix from deposition to sampling, and
• Length of time in the soil until sampling occurs.
51
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Beginning and
end of sample
Incident count
1 1 1
to
1 1 1
t5 t1 t2 tg
Decay corrected Sample
to before Date
sampling
I
I
Projected
activity
^
Figure 6 - Timeline for IND Parent-Progeny Activity Determinations
Each combination of the times and element solubilities noted here will represent a different case
and will require a different solution (some much more complicated than others). The last column
of Table 5 identifies a general method to be used once it has been established that equilibrium
has been achieved. Figure 6 shows the sequence of events on a general timeline. These will be
used in examples further on in this discussion.
Radionuclide results are generally decay corrected to the date and time of the sample collection.
However, since the radionuclides in the decay chain will form the parent-progeny relationships
starting with the event, it will take several hours to weeks until transient equilibrium26 for the
fission product pairs noted above will take effect. A simple default decay correction factor based
on delta days between collection and analysis will require additional calculation outside the
normal software options used in most gamma spectrometry systems.
For the transient equilibrium cases the half-life of the parent is used for decay corrections
(backwards and forwards in time). Note for the 95Zr/ 5Nb pair that the time to achieve
equilibrium is about 67 days. This means that some additional assumptions may need to be made
and additional calculations involving an ingrowth formula would be needed, if equilibrium has
not yet been established (see Example 1, below).
For the no equilibrium cases the half-life of the progeny is used for decay corrections (backwards
and forwards in time). Note that for the 147Nd/147Pm pair, the time for 147Pm to decay with its
characteristic half-life is rather long: about 72 days. This means that some additional
assumptions may need to be made and additional calculations involving an ingrowth formula
would be needed, if equilibrium has not yet been established. Also note that for the 131I/131mXe
pair that xenon is a noble gas and this may cause issues with sample storage and handling, as
well as with decay correction.
For all of these cases, the project MQOs will need to specify the assumptions to be made
regarding the level of equilibrium in the sample that is to be assumed at the time of sampling.
Additionally, specific equations that support the MQOs should be established in the project plan
so that the assumptions and equations are consistently applied.
Some secular equilibrium pairs are not noted in the table as their time to equilibrium is measured in minutes.
Examples of these are 137Cs/137mBa, 103Ru/103Rh, and 106Ru/106Rh.
52
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Two examples will provide some guidance on the details of correct decay calculations for these
parent-progeny relationships.
Example 1
An incident has occurred on Day 0 at 1200 hours (to). A soil sample is taken on Day 5 at 1200
hours (/i) and sent to a laboratory for analysis of 95Zr-95Nb. The laboratory decay corrects the
sample activity concentration to the start of the count time, Day 7 at 1200 hours (^2). The 1C
wants to know what the activity concentration will be on Day 15 at 1200 hours (£4). The
measured activity concentration of 95Zr is !><104pCi/g and for 95Nb is 600 pCi/g, decay corrected
to the beginning of the sample count time (t^).
Step 1. Assumptions. The chemical reactivity of the zirconium and niobium may not be exactly
the same. Thus, from the time of the event to the time of soil deposition some chemical
separation of the two may occur resulting in a non-predictable activity concentration of the
progeny based on the parent.
Question: Is all of the 95Nb in the soil sample supported, or is there unsupported 95Nb?
Answer. Decay-correct the activity concentration of the sample for the parent (95Zr in this case)
to the time the sample was taken. Use that value to determine what the activity concentration of
supported 95Nb will be at the time of analysis. If the activity concentration at the time of analysis
is different from that calculated based on the parent, two conditions can exist:
• Sample progeny activity concentration is greater than calculated (unsupported progeny is
present)
• Sample progeny activity concentration is less than calculated (chemical separation of
parent and progeny has occurred before after deposition)
Both of these can be solved for the activity concentration of the progeny using the generalized
formulas
(1)
An = Ane-t (2)
Where: Xd is the decay constant of the progeny
Xpis the decay constant of the parent
V is the decay constant of radionuclide n
At is the time between to and the time of analysis
Nd is the number of progeny atoms
Np is the number of parent atoms
o refers to the parameter at time t = 0
53
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Step 2. Decay-correct parent activity concentration. The activity concentration of the parent is
unaffected by that of the progeny. Decay correct the activity concentration of the parent from
time t2 (analysis date) tO time t\ (collection date)-
= 1.02xl04pCi/g
Step 3. Calculate the theoretical progeny activity concentration. Using Equation 1, where AI is
Ap° and the term, AdNde~Adt, is set to zero (assumes progeny is only present from parent), the
theoretical value of the progeny activity concentration at the time of analysis (^2) is 392 pCi/g.
Step 4. Calculate the unsupported activity concentration for day 2. This is the difference between
theoretical and measured progeny activity concentration or (600 - 392) = 208 pCi/g.
Step 5. Calculate the activity concentration for both radionuclides at Day 15.
2.2056 x 1 x W4pCi/g[e-°m081 d~lx8d - e -0.01982^*8 d] + 208 x e-°-01982 d-^
= 1.58xl03pCi/g
AZr = ^e-^-ti) = (IxlO4 pCi/^)(e-a°1081d"1*8d) = 9.17xl03 pd/g
The activities on Day 15 for the radionuclides are: 95Zr = 9.1?xl03 pCi/g and 95Nb = 1.58xl03
pCi/g.
Example 2
An IND is detonated on Day 1. A soil sample is taken and sent to the lab on Day 30. Gamma
spectrometry measurements at 1200 hours on Day 30 for 140Ba and 140La are 1.03xl06 pCi/g and
1.18xl06pCi/g, respectively. Several members of the public were exposed in the area where this
soil was taken on Day 5 of the event. This was not discovered until the samples were taken. The
1C wants to know what the activities of these two radionuclides were on Day 5 1200 hours for
the purposes of dose reconstruction.
Step 1: Assumption: the deposition of the material occurred within the first 5 days of the
detonation. Is any 140La in the soil sample analyzed on Day 30, unsupported? Although the two
radionuclides are chemically different, after 25 days any unsupported lanthanum would be
reduced to ~ 3 x 10~3% (14.9 half-lives) of what it was on Day 5.
Step 2: Decay correct the parent 140Ba back to Day 1 using Equation (2).
to) = i.03xl06 x eo.o5435xso = 5 26 x 106 pCi/g
54
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Caution: although the progeny is decaying forward with the half-life of the parent, it is not advisable
to decay correct backwards in time. This is because the curve goes through a maximum that cannot be
accounted for by simple exponential decay using Equation (2).
Step 3: Calculate the activity of the progeny on Day 5 using Equation (1)
/( , M , — A ,
/Ldjvd "-La
= (0413°^035345)5.26 x lOViMe-0-05345"'1*5" - e-0-413 d-lx5d] = 3.85 x 106 pCi/g
Step 4: Calculate the activity concentration of the parent on Day 5.
ABa = A0Bae-°-05345d~lx5 d = 4.03 x 106 pd/g
Alpha and Beta Analysis
The most significant alpha emitter concentrations will be due to fissile material that has not
undergone fission and some transuranic elements (TRU) formed as a result of multiple neutron
capture on fissile material during the detonation. The principal alpha emitting radionuclides will
likely be 234U, 235U, 238U, and 239Pu (if 235U is used as the fissile material), and 239Pu, 240Pu, and
941 9^Q
Am (if Pu is used as the fissile material). A gross alpha screen directly on samples will
suffer from significant self-shielding compromising any assessment of the alpha contribution. In
Scenario 3, this assessment is postponed until after the samples have been dried, oxidized, fused,
and dissolved as this will eliminate a good deal of material that would attenuate the alpha signal.
It also is also possible that the leftover fissile material will be present as discrete radioactive
particles (DRPs) and may be missed on an initial screening based on the particle size.
The most significant beta-only emitters from such an incident will be 89Sr and 90Sr. Both
radionuclides will distribute in the same manner (chemically and physically) in the environment
since they are chemically identical. Both radionuclides have high fission yields, thus their
activity concentration will be significant. However, the 89Sr contribution will decrease
measurably due to its half-life (50 days). At the time of the incident the ratio of activity of
89Sr/90Sr will be approximately 167, and after 180 days will be 14.3.
There are several other beta-only emitting radionuclides: 99Tc, 129I, 93Nb, 135Cs, 241Pu, and others.
However, their long half-lives translate into low-activity concentrations relative to the gamma
emitters and the radiostrontiums. Thus, from the IND perspective they are a much less significant
contributor to the total activity concentration and dose. Therefore, for the short-term dose
assessment (1,000-mrem PAG) in terms of activity concentration they will be insignificant
contributors. When the 50-year exposure risk is assessed their activity concentration may need to
be determined as they may contribute significantly to the long-term dose.
55
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
APPENDIX I. TABLES OF RADIOANALYTICAL PARAMETERS FOR
RADIONUCLIDES OF CONCERN
The following tables list the AAL, ADL, and WMR values for the radionuclides of concern. The
tables contain calculated activity concentration values for gross screening or radionuclide-
specific measurements for alpha, and beta/gamma-emitting radionuclides, respectively.
Derivation of the ADL values for each of these tables can be found in Appendix VI. Tables 6, 7,
8, and 10 contain calculated activities for specific radionuclides. These values were calculated
based on the Type I and Type II error rates presented in Appendix VI.27 Table 9 identifies some
radionuclides and their constants associated with an IND event.
The AALs in the tables in this appendix may be used as default values. They are based on
generic conversions of the PAGs and risk-based dose levels to concentration in soil for a specific
radionuclide based on decay and weathering.
The MMR and ADL will change depending upon the acceptable decision error rate. The 1C may
provide incident-specific AALs or decision error rates that would supersede the values presented
here. In this case, the laboratory will need to develop new tables for all values using the process
described in Appendix VI.
The values represent the concentration found at the time of sampling. The PAG or risk-based
numbers are derived from that concentration, for total dose at a time in the future, taking into
account radioactive decay, resuspension, and weathering. All values in the tables have been
rounded to two significant figures. The methodology, assumptions, and calculations that were
used to derive these numbers can be found in FRMAC (2010).
FRMAC provides examples of using "marker radionuclides," i.e., gamma ray emitters, when
screening samples to assess the potential of an individual sample exceeding PAG or risk-based
limits without processing the sample for each radionuclide that may be present. Such an
assessment relies on the fact that the distribution of radionuclides in the soil samples will be
similar to those that have already been analyzed using radionuclide-specific methods. The
screening process can then be used to estimate the sum of the fractions for all radionuclides
assumed to be present and provide insight to incident command staff as to the degree of
contamination. Decisionmakers should keep in mind that a full radiochemical analysis of the
samples needs to be performed before these assumptions can be verified. Other factors to be
considered are based on very broad assumptions, such as:
• Is the radionuclide mixture the same?
• Are there hot particles?
• How will weathering and resuspension affect dose?
Thus, it may be possible to draw preliminary conclusions from screening, but only if the relation
of the marker radionuclide to other radionuclides is shown to be constant.28
27 A Type I error refers to rejecting the null hypothesis when it is true. A Type I decision error is sometimes called a
"false rejection" or a "false positive."
28 An example of this is that 137Cs/89Sr ratios may have one value close to the event site in time and location while
mobility and atmospheric transport/chemistry will change the ratios at points distant in time and location. Thus,
location and time factors should be used in assumption/estimates.
56
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
FRMAC also has doses for a two-year exposure period that are not included in this document. One
reason is that several of the radionuclides that are short lived (half-lives of a few hours to several
days) yield absurdly large values for the PAGs and action levels at two years. The proposed
analytical action levels in this document can be easily adapted to most situations. If a specific event
requires the two-year value PAGs of 500 mrem, FRMAC (2010) should be consulted.
Some of the assumptions made in the document to arrive at the values in these tables are:
• EPA Lifetime Excess Total Cancer Risk = 8.46x 1(T7 risk/mrem (FGR-13,29 Table 7.6, p. 182)
• RiskLevel: IxlO^or IxlO^5
• PAGs: Early Phase = 1,000 mrem, 4 days
• First Year = 2,000 mrem
• Second Year = 500 mrem
• Fifty Year = 5,000 mrem
• Deposition Derived Response Level (DRL) (Dep_DRL) taken from Appendix C of the FRMAC
Manual (FRMAC 2010) or calculated using TurboFRMAC 2010 (jiCi/nr)
• Sample size: 100 cm2 x 2 cm deep (200 cm3)
• Soil density: 1.6g/cm3
Table 6A - Analytical Action and Decision Levels (AAL and ADL) and
Required Method Uncertainty Corresponding to Early Phase and First Year PAGs in Soil
Using Gross Alpha Screening Methods
Radionuclide
Gross AlphaL1J
Am-241
Cm-242
Cm-243
Cm-244
Np-237
Po-210
Pu-238
Pu-239
Pu-240
Ra-226
Th-228
Th-230
Th-232
U-234
U-235
U-238
U-Nat
Early Phase 1,000-mrem PAG
AAL
pCi/g
8.6xl03
1.7xl03
2.7xl04
2.3xl03
2.8xl03
3.1xl03
3.8xl04
1.5xl03
1.3xl03
1.3xl03
8.6xl03
3.2xl03
1.6xl03
ADL
pCi/g
4.3xl03
830
1.4xl04
l.lxlO3
1.4xl03
1.6xl03
1.9xl04
740
670
670
4.3xl03
1.6xl03
780
MMR
pCi/g
2.6xl03
500
8.2xl03
690
850
950
l.lxlO4
450
410
410
2.6xl03
960
480
First Year 2,000 mrem PAG
AAL
pCi/g
410
l.lxlO3
2.2xl04
1.3xl03
1.9xl03
1.3xl03
3.2xl04
l.OxlO3
930
930
410
500
l.lxlO3
ADL
pCi/g
210
550
l.lxlO4
630
970
650
1.6xl04
510
460
460
210
250
540
MMR
pCi/g
130
340
6.7xl03
380
590
400
9.6xl03
310
280
280
130
150
330
Activity concentration for this radionuclide is not available.
1.7xl04
1.7xl04
1.8xl04
1.8xl04
8.5xl03
8.5xl03
9.1xl03
9.1xl03
5.2xl03
5.2xl03
5.6xl03
5.6xl03
1.2xl04
3.3xl03
4.0xl03
4.0xl03
5.8xl03
1.6xl03
2.0xl03
2.0xl03
3.5xl03
990
1.2xl03
1.2xl03
Note:
[1] The AAL, ADL and MMR values for gross alpha shown in this table are for 226Ra.
radionuclides have been identified for an incident, the radionuclide with the lowest AAL,
values should be selected for the respective gross activity screening measurements.
Once specific
ADL and
29Federal Guidance Technical Report 13, Cancer Risk Coefficients for Environmental Exposure to Radionuclide:
Updates and Supplements, www.epa.gov/radiation/federal/techdocs.htmlfaeportl3.
57
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Table 6B - Analytical Action and Decision Levels (AAL and ADL) and
Required Method Uncertainty Corresponding to Early Phase and First Year PAGs for Soil
Using Gross Beta/Gamma Screening Methods
Radionuclide
Gross Beta[1] [2]
Gross Gamma[2]
Ac-227+DP
Ce-141
Ce-144
Co-57
Co-60
Cs-134
Cs-137
1-125
1-129
1-131
Ir-192
Mo-99
P-32
Pd-103
Pu-241
Ra-228
Ru-103
Ru-106
Se-75
Sr-89
Sr-90
Tc-99
Early Phase 1,000-mrem PAG
AAL
pCi/g
2.1xl05
1.3xl04
900
4.4xl05
1.6xl05
2.7xlQ5
1.3xl04
2.0xl04
5.4xl04
9.3xlQ5
l.lxlQ6
9.6xl04
3.9xl04
1.7xl05
3.8xl05
3.8xl06
7.0xl04
7.8xl03
6.5xl04
8.4xl04
8.5xl04
4.4xl05
2.1xl05
1.2xl07
ADL
pCi/g
l.lxlQ5
6.5xl03
450
2.2xl05
8.0xl04
1.4xl05
6.5xl03
l.OxlO4
2.7xlQ4
4.6xl05
5.6xl05
4.8xl04
2.0xl04
8.5xl04
1.9xl05
1.9xl06
3.5xl04
3.9xl03
3.2xl04
4.2xl04
4.2xl04
2.2xl05
l.lxlQ5
5.8xl06
MMR
pCi/g
6.4xl04
3.9xl03
270
1.3xl05
4.8xl04
8.3xlQ4
3.9xl03
6.1xl03
1.6xl04
2.8xl05
3.4xl05
2.9xl04
1.2xl04
5.2xl04
1.2xl05
l.lxlQ6
2.1xl04
2.4xl03
2.0xl04
2.5xl04
2.6xl04
1.3xl05
6.4xl04
3.6xl06
First Year 2,000 mrem PAG
AAL
PCi/g
6.4xl03
330
440
7.5xl04
5.9xl03
9.9xl03
330
560
1.3xl03
9.1xl04
3.5xl04
5.7xlQ4
3.1xl03
2.2xl05
1.4xl05
1.2xl06
4.9xl04
800
9.1xl03
2.8xl03
4.7xlQ3
4.9xl04
6.4xl03
4.7xlQ6
ADL
pCi/g
3.2xl03
160
220
3.7xlQ4
3.0xl03
5.0xl03
160
280
660
4.5xlQ4
1.8xl04
2.8xl04
1.6xl03
l.lxlQ5
6.8xl04
5.8xl05
2.4xl04
400
4.6xl03
1.4xl03
2.3xlQ3
2.5xlQ4
3.2xl03
2.4xl06
MMR
pCi/g
1.9xl03
100
130
2.3xlQ4
1.8xl03
3.0xl03
100
170
400
2.8xl04
l.lxlQ4
1.7xl04
950
6.6xl04
4.2xl04
3.5xl05
1.5xl04
240
2.8xl03
860
1.4xl03
1.5xl04
1.9xl03
1.4xl06
Note:
[1] Several nuclides in this table decay by electron capture. These radionuclides cannot be detected using gross
P analysis. The electron capture decay leads to characteristic X-rays of the progeny radionuclide. The most
effective way to detect the specific X-rays from these electron-capture-decay radionuclides is either with a
low-energy photon detector (LEPD) or a reverse electrode germanium detector (N-type semiconductor
detector). The lower range of energy with these detectors is about 10 keV. Alternatively liquid scintillation
counting could be used as a gross indicator of activity concentration.
[2] The AAL, ADL and MMR values for gross beta shown in this table are for 90Sr. The AAL, ADL and MMR
values for gross gamma shown in this table are for 60Co. Once specific radionuclides have been identified
for an incident, the radionuclide with the lowest AAL, ADL and MMR values should be selected for the
respective gross activity screening measurements.
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Table 6C - Analytical Action and Decision Levels (AAL and ADL) and
Required Method Uncertainty Corresponding to Early Phase and First Year PAGs for Soil
Using Radionuclide-Specific Methods for Alpha Emitters
Radionuclide
Am-241
Cm-242
Cm-243
Cm-244
Np-237
Po-210
Pu-238
Pu-239
Pu-240
Ra-226
Th-228
Th-230
Th-232
U-234
U-235
U-238
U-Nat
Early Phase 1,000-mrem PAG
AAL
pCi/g
1.7xl03
2.7xl04
2.3xl03
2.8xl03
3.1xl03
3.8xl04
l.SxlO3
1.3xl03
1.3xl03
8.6xl03
3.2xl03
1.6xl03
ADL
pCi/g
1.2xl03
1.9xl04
1.6xl03
2.0xl03
2.2xl03
2.7xl04
l.OxlO3
950
950
6.1xl03
2.2xl03
l.lxlO3
MMR
pCi/g
210
3.4xl03
290
350
390
4.7xl03
190
170
170
l.lxlO3
400
200
First Year 2,000 mrem PAG
AAL
PCi/g
l.lxlO3
2.2xl04
1.3xl03
1.9xl03
1.3xl03
3.2xl04
l.OxlO3
930
930
410
500
l.lxlO3
ADL
pCi/g
780
1.6xl04
890
1.4xl03
920
2.2xl04
720
660
660
290
360
760
MMR
pCi/g
140
2.8xl03
160
240
160
4.0xl03
130
120
120
52
63
140
Activity concentration for this radionuclide is not available.
1.7xl04
1.7xl04
1.8xl04
1.8xl04
1.2xl04
1.2xl04
1.3xl04
1.3xl04
2.1xl03
2.1xl03
2.3xl03
2.3xl03
1.2xl04
3.3xl03
4.0xl03
4.0xl03
8.2xl03
2.3xl03
2.8xl03
2.8xl03
1.5xl03
410
510
510
59
-------
Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Table 6D - Analytical Action and Decision Levels (AAL and ADL) and
Required Method Uncertainty Corresponding to Early Phase and First Year PAGs for Soil
Using Radionuclide-Specific Methods for Beta/Gamma Emitters
Radionuclide
Ac-227+DP
Ce-141
Ce-144
Co-57
Co-60
Cs-134
Cs-137
1-125
1-129
1-131
Ir- 192
Mo-99
P-32
Pd-103
Pu-241
Ra-228
Ru-103
Ru-106
Se-75
Sr-89
Sr-90
Tc-99
Early Phase 1,000-mrem PAG
AAL
pCi/g
900
4.4xl05
1.6xl05
2.7xlQ5
1.3xl04
2.0xl04
5.4xl04
9.3xlQ5
l.lxlQ6
9.6xl04
3.9xl04
1.7xl05
3.8xl05
3.8xl06
7.0xl04
7.8xl03
6.5xlQ4
8.4xl04
8.5xlQ4
4.4xl05
2.1xl05
1.2xl07
ADL
pCi/g
640
3.1xl05
l.lxlQ5
1.9xl05
9.2xl03
1.4xl04
3.8xl04
6.6xl05
7.9xl05
6.8xl04
2.8xl04
1.2xl05
2.7xlQ5
2.7xlQ6
4.9xl04
5.5xl03
4.6xl04
5.9xl04
6.0xl04
3.1xl05
l.SxlO5
8.3xlQ6
MMR
pCi/g
110
5.6xl04
2.0xl04
3.5xl04
1.6xl03
2.5xl03
6.8xl03
1.2xl05
1.4xl05
1.2xl04
4.9xl03
2.2xl04
4.8xl04
4.7xlQ5
8.8xl03
980
8.2xl03
l.lxlQ4
l.lxlQ4
5.5xl04
2.7xlQ4
l.SxlO6
First Year 2,000 mrem PAG
AAL
PCi/g
440
7.5xl04
5.9xl03
9.9xl03
330
560
1.3xl03
9.1xl04
3.5xl04
5.7xlQ4
3.1xl03
2.2xl05
1.4xl05
1.2xl06
4.9xl04
800
9.1xl03
2.8xl03
4.7xlQ3
4.9xl04
6.4xl03
4.7xlQ6
ADL
pCi/g
310
5.3xlQ4
4.2xl03
7.0xl03
230
400
930
6.4xl04
2.5xlQ4
4.0xl04
2.2xl03
l.SxlO5
9.7xlQ4
8.2xl05
3.4xl04
560
6.5xlQ3
2.0xl03
3.3xlQ3
3.5xlQ4
4.5xlQ3
3.3xlQ6
MMR
pCi/g
55
9.4xl03
750
1.3xl03
42
71
170
l.lxlQ4
4.5xl03
7.1xl03
390
2.7xlQ4
1.7xl04
1.5xl05
6.1xl03
100
l.lxlQ3
350
590
6.2xl03
810
5.9xl05
60
-------
Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Table 7A - Analytical Action and Decision Levels (AAL and ADL) and Required Method
Uncertainty Corresponding to First Year Exposure at lO^and 10~6 Risk for Soil
Using Gross Alpha Screening Methods
Radionuclide
Am-241
Cm-242
Cm-243
Cm-244
Np-237
Po-210
Pu-238
Pu-239
Pu-240
Ra-226
Th-228
Th-230
Th-232
U-234
U-235
U-238
U-Nat
AAL
10~4 risk
pCi/g
65
1.3xl03
75
110
77
1.9xl03
60
55
55
24
30
64
ADL
10~4 risk
pCi/g
33
650
37
57
38
930
30
27
27
12
15
32
WMR
10~4 risk
pCi/g
20
390
23
35
23
570
18
17
17
7.4
9.0
19
AAL
10~6 risk
pCi/g
0.65
13
0.75
1.1
0.77
19
0.60
0.55
0.55
0.24
0.30
0.64
ADL
10~6 risk
PCi/g
0.33
6.5
0.37
0.57
0.38
9.3
0.30
0.27
0.27
0.12
0.15
0.32
WMR
10~6 risk
pCi/g
0.20
3.9
0.23
0.35
0.23
5.7
0.18
0.17
0.17
0.074
0.090
0.19
Activity concentration for this radionuclide is not available.
690
190
240
240
340
96
120
120
210
58
72
72
6.9
1.9
2.4
2.4
3.4
0.96
1.2
1.2
2.1
0.58
0.72
0.72
61
-------
Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Table 7B - Analytical Action and Decision Levels (AAL and ADL) and Required Method
Uncertainty Corresponding to First Year Exposure at 10"4 and 10~6 Risk for Soil
Using Gross Beta/Gamma Screening Methods
Radionuclide
Ac-227+DP
Ce-141
Ce-144
Co-57
Co-60
Cs-134
Cs-137
1-125
1-129
1-131
Ir- 192
Mo-99
P-32
Pd-103
Pu-241
Ra-228
Ru-103
Ru-106
Se-75
Sr-89
Sr-90
Tc-99
•AAL
10^ risk
pCi/g
26
4.4xl03
350
590
20
^^^^B
78
5.4xl03
2.1xl03
3.3xl03
180
1.3xl04
S.lxlO3
6.9xl04
2.9xl03
47
540
170
280
2900
380
2.8xl05
ADL
10"4 risk
PCi/g
13
2.2xl03
180
290
9.8
17
39
2.7xl03
l.OxlO3
1.7xl03
92
6.4xl03
4.0xl03
3.4xl04
1.4xl03
24
270
83
140
l.SxlO3
190
1.4xl05
"MR
10"4 risk
pCi/g
7.9
1.3xl03
110
180
5.9
10
24
1.6xl03
640
l.OxlO3
56
3.9xl03
2.5xl03
2.1xl04
870
14
160
51
84
890
110
8.5xl04
AAL
10"6 risk
pCi/g
0.26
44
3.5
5.9
0.20
0.33
0.78
54
21
33
1.8
130
81
690
29
0.47
5.4
1.7
2.8
29
3.8
2.8xl03
ADL
lO^6 risk
pCi/g
0.13
22
1.8
2.9
0.098
0.17
0.39
27
10
17
0.92
64
40
340
14
0.24
2.7
0.83
1.4
15
1.9
1.4xl03
WMR
10"6 risk
pCi/g
0.079
13
1.1
1.8
0.059
0.10
0.24
16
6.4
10
0.56
39
25
210
8.7
0.14
1.6
0.51
0.84
8.9
1.1
850
62
-------
Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Table 7C - Analytical Action and Decision Levels (AAL and ADL) and Required Method
Uncertainty Corresponding to First Year Exposure at 10"4 and 1(T6 Risk for Soil
Using Radionuclide-Specific Methods for Alpha Emitters
Radionuclide
Am-241
Cm-242
Cm-243
Cm-244
Np-237
Po-210
Pu-238
Pu-239
Pu-240
Ra-226[1]
Th-228
Th-230
Th-232
U-234
U-235
U-238
U-Nat
AAL
10~4 risk
pCi/g
65
1.3xl03
75
110
77
1.9xl03
60
55
55
24
30
64
ADL
10~4 risk
PCi/g
46
920
53
81
54
1.3xl03
43
39
39
17
21
45
WMR
10~4 risk
pCi/g
8.2
160
9.4
14
9.7
230
7.6
6.9
6.9
3.1
3.7
8.0
AAL
10~6 risk
pCi/g
0.65
13
0.75
1.1
0.77
19
0.60
0.55
0.55
0.24
0.30
0.64
ADL
10~6 risk
pCi/g
0.46
9.2
0.53
0.81
0.54
13
0.43
0.39
0.39
0.17
0.21
0.45
WMR
10 6 risk
pCi/g
0.82
1.6
0.094
0.14
0.097
2.3
0.076
0.069
0.069
0.031
0.037
0.080
Activity concentration for this radionuclide is not available.
690
190
240
240
490
140
170
170
87
24
30
30
6.9
1.9
2.4
2.4
4.9
1.4
1.7
1.7
0.87
0.24
0.30
0.30
Note:
[1] The AAL for 226Ra at the KT6 risk is less than that concentration normally found in most soils. While these
calculations are technically correct, it is unlikely that such an action level concentration would ever be applied
to incident-response samples.
63
-------
Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Table 7D - Analytical Action and Decision Levels (AAL and ADL) and Required Method
Uncertainty Corresponding to First Year Exposure at lO^and 1(T6 Risk for Soil
Using Radionuclide-Specific Methods for Beta/Gamma Emitters
Radionuclide
Ac-227+DP
Ce-141
Ce-144
Co-57
Co-60
Cs-134
Cs-137
1-125
1-129
1-131
Ir- 192
Mo-99
P-32
Pd-103
Pu-241
Ra-228[1]
Ru-103
Ru-106
Se-75
Sr-89
Sr-90
Tc-99
AAL
10~4 risk
pCi/g
26
4.4xl03
350
590
20
33
78
5.4xl03
2.1xl03
3.3xlQ3
180
1.3xl04
S.lxlO3
6.9xl04
2.9xl03
47
540
170
280
2.9xl03
380
2.8xl05
ADL
10"4 risk
PCi/g
18
3.1xl03
250
410
14
24
55
3.8xl03
1.5xl03
2.4xl03
130
9.1xl03
5.7xlQ3
4.8xl04
2.0xl03
33
380
120
200
2.1xl03
270
2.0xl05
"MR
10"4 risk
pCi/g
3.3
560
44
74
2.5
4.2
9.8
680
260
420
23
1.6xl03
l.OxlO3
8.6xl03
360
5.9
68
21
35
370
48
3.5xl04
AAL
10~6 risk
pCi/g
0.26
44
3.5
5.9
0.20
0.33
0.78
54
21
33
1.8
130
81
690
29
0.47
5.4
1.7
2.8
29
3.8
2.8xl03
ADL
10~6 risk
pCi/g
0.18
31
2.5
4.1
0.14
0.24
0.55
38
15
24
1.3
91
57
480
20
0.33
3.8
1.2
2.0
21
2.7
2.0xl03
"MR
10~6 risk
pCi/g
0.033
5.6
0.44
0.74
0.025
0.042
0.098
6.8
2.6
4.2
0.23
16
10
86
3.6
0.059
0.68
0.21
0.35
3.7
0.48
350
Note:
[1] The AAL for 228Ra at the KT6 risk is less than that concentration normally found in most soils. While these
calculations are technically correct, it is unlikely that such an action level concentration would ever be applied
to incident-response samples.
64
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Table 8A - Analytical Action and Decision Levels (AAL and ADL) and
Required Method Uncertainty Corresponding to Risk Limits for 50-Year Exposure for Soil
Using Gross Alpha Screening Methods
Radionuclide
Am-241
Cm-242
Cm-243
Cm-244
Np-237
Po-210
Pu-238
Pu-239
Pu-240
Ra-226[3]
Th-228[3]
Th-230
Th-232
U-234
U-235
U-238
U-Nat
AAL
10~4 risk
pCi/g
15
1.3xl03
^^^^|
52
6.3
1.8xl03
19
^^^^|
^^^^|
^^^^|
^^^^|
17
ADL
10~4 risk
PCi/g
7.7
640
7.1
26
3.1
920
9.4
7.5
7.5
0.52
6.2
8.7
WMR
10~4 risk
pCi/g
4.7
390
4.3
16
1.9
560
5.7
4.6
4.6
0.31
3.8
5.3
AAL
10~6 risk [2]
pCi/g
0.15
13
0.14
0.52
0.063
18
0.19
0.15
0.15
0.010
0.12
0.17
ADL
10~6 risk
pCi/g
0.077
6.4
0.071
0.26
0.031
9.2
0.094
0.075
0.075
5.2xlO~3
0.062
0.087
WMR
10~6 risk
pCi/g
0.047
3.9
0.043
0.16
0.019
5.6
0.057
0.046
0.046
3.1xlO~3
0.038
0.053
Activity concentration for this radionuclide is not available.
180
^^^^|
^^^^|
13
89
5.0
6.5
6.5
54
3.0
3.9
3.9
1.8
0.10
0.13
0.13
0.89
0.050
0.065
0.065
0.54
0.030
0.039
0.039
Notes:
[1] Values are based on the dose conversion factors taken from Appendix C of the FRMAC Manual (FRMAC
2010) or calculated using TurboFRMAC 2010 available from Sandia National Laboratory.
[2] The stated Ra, U, and Th AALs for the 10~6 risk levels may be below the inherent concentrations in typical
soils. While these calculations are technically correct, it is unlikely that such an action level concentration
would ever be applied to incident-response samples.
[3] Includes decay products originating from the 226Ra or 228Th in the body.
65
-------
Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Table 8B - Analytical Action and Decision Levels (AAL and ADL) and
Required Method Uncertainty Corresponding to Risk Limits for 50-Year Exposure for Soil
Using Gross Beta/Gamma Screening Methods
Radionuclide
Ac-227+DP
Ce-141
Ce-144
Co-57
Co-60
Cs-134
Cs-137
I-125[1]
1-129
1-131
Ir- 192
Mo-99
P-32
Pd-103[1]
Pu-241
Ra-228[2]
Ru-103
Ru-106
Se-75[1]
Sr-89
Sr-90
Tc-99
AAL
10~4 risk
pCi/g
j^Hj^n
4.4xl03
220
380
3.5
I^H^n
4.9
5.3xl03
86
3.3xl03
I^^^H!
1.3xl04
S.lxlO3
6.9xl04
1.4xl03
I^^^H!
I^H^HI
93
250
2.9xl03
24
2.2xl04
ADL
10~4 risk
PCi/g
2.2
2.2xl03
110
190
1.7
5.9
2.4
2.6xl03
43
1.7xl03
90
6.4xl03
4.0xl03
3.4xl04
710
4.3
270
46
120
1.5xl03
12
l.lxlO4
WMR
10"4 risk
pCi/g
1.3
1.3xl03
68
120
1.1
3.6
1.5
1.6xl03
26
l.OxlO3
54
3.9xl03
2.5xl03
2.1xl04
430
2.6
160
28
75
880
7.3
6.7xl03
AAL
10~6 risk
pCi/g
0.044
44
2.2
3.8
0.035
0.12
0.049
53
0.86
33
1.8
130
81
690
14
0.087
5.4
0.93
2.5
29
0.24
220
ADL
10~6 risk
pCi/g
0.022
22
1.1
1.9
0.017
0.059
0.024
26
0.43
17
0.90
64
40
340
7.1
0.043
2.7
0.46
1.2
15
0.12
110
WMR
10~6 risk
pCi/g
0.013
13
0.68
1.2
0.011
0.036
0.015
16
0.26
10
0.54
39
25
210
4.3
0.026
1.6
0.28
0.75
8.8
0.073
67
Notes:
[1] 1-125, Se-75, and Pd-103 decay by electron capture. These radionuclides cannot be detected using gross (3
screening analysis. They emit low-energy gamma rays and also X-rays from their respective progeny
radionuclides. Liquid scintillation counting could be used as a gross screening technique for the presence of
these radionuclides and other electron capture decay radionuclides.
[2] The AAL for 228Ra at the KT6 risk is less than that concentration normally found in most soils. While these
calculations are technically correct, it is unlikely that such an action level concentration would ever be applied
to incident-response samples.
66
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Table 8C - Analytical Action and Decision Levels (AAL and ADL) and
Required Method Uncertainty Corresponding to Risk Limits for 50-Year Exposure for Soil
Using Radionuclide-Specific Methods for Alpha Emitters
Radionuclide
Am-241
Cm-242
Cm-243
Cm-244
Np-237
Po-210
Pu-238
Pu-239
Pu-240
Ra-226[1]
Th-228[1]
Th-230[1]
Th-232[1]
U-234[1]
U-235[1]
U-238[1]
U-Nat[1]
AAL
10~4 risk
pCi/g
{^^^•1
1.3xl03
I^H^ri
52
6.3
1.8xl03
19
{^^^•1
I^H^ri
I^H^ri
{^^^•1
17
ADL
10~4 risk
PCi/g
11
900
10
37
4.4
1.3xl03
13
11
11
0.73
8.8
12
WMR
10~4 risk
pCi/g
1.9
160
1.8
6.6
0.79
230
2.4
1.9
1.9
0.13
1.6
2.2
AAL
10~6 risk
pCi/g
0.15
13
0.14
0.52
0.063
18
0.19
0.15
0.15
0.010
0.12
0.17
ADL
10~6 risk
pCi/g
0.11
9.0
0.10
0.37
0.044
13
0.13
0.11
0.11
7.3 x!0~3
0.088
0.12
WMR
10~6 risk
pCi/g
0.019
1.6
0.018
0.066
7.9xlO~3
2.3
0.024
0.019
0.019
1.3xlO~3
0.016
0.022
Activity concentration for this radionuclide is not available.
180
I^H^H
I^H^ri
13
130
7.1
9.2
9.2
23
1.3
1.6
1.6
1.8
0.10
0.13
0.13
1.3
0.071
0.092
0.092
0.23
0.013
0.016
0.016
Note:
[1] The stated Ra,
soils.
U, and Th AALs for the 10 6 risk levels may be below the inherent concentrations in typical
67
-------
Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Table 8D - Analytical Action and Decision Levels (AAL and ADL) and
Required Method Uncertainty Corresponding to Risk Limits for 50-Year Exposure for Soil
Using Radionuclide-Specific Methods for Beta/Gamma Emitters
Radionuclide
Ac-227+DP
Ce-141
Ce-144
Co-57
Co-60
Cs-134
Cs-137
1-125
1-129
1-131
Ir- 192
Mo-99
P-32
Pd-103
Pu-241
Ra-228
Ru-103
Ru-106
Se-75
Sr-89
Sr-90
Tc-99
AAL
10~4 risk
pCi/g
I^M^M
4.4xl03
220
380
3.5
I^^^H!
4.9
5.3xl03
86
3.3xl03
I^^^H!
1.3xl04
S.lxlO3
6.9xl04
1.4xl03
(^^^•1
t^H^n
93
250
2.9xl03
24
2.2xl04
ADL
10"4 risk
pCi/g
3.1
3.1xl03
160
270
2.5
8.3
3.4
3.7xl03
61
2.4xl03
130
9.1xl03
5.7xl03
4.8xl04
l.OxlO3
6.1
380
65
180
2.1xl03
17
1.6xl04
WMR
10"4 risk
pCi/g
0.55
550
28
48
0.44
1.5
0.61
670
11
420
23
1.6xl03
l.OxlO3
8.6xl03
180
1.1
68
12
31
370
3.0
2.8xl03
AAL
10~6 risk
pCi/g
0.044
44
2.2
3.8
0.035
0.12
0.049
53
0.86
33
1.8
130
81
690
14
0.087
5.4
0.93
2.5
29
0.24
220
ADL
10~6 risk
pCi/g
0.031
31
1.6
2.7
0.025
0.083
0.034
37
0.61
24
1.3
91
57
480
10
0.061
3.8
0.65
1.8
21
0.17
160
WMR
10~6 risk
PCi/g
5.5xlO~3
5.5
0.28
0.48
4.4xlO~3
150
6.1xlO~3
6.7
0.11
4.2
0.23
16
10
86
1.8
0.011
0.68
0.12
0.31
3.7
0.030
28
68
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Table 9 -Additional Radionuclides Potentially Present in Soil
Immediately Following an IND
Radionuclide
239Np
24Na
133Xe
131mXe
132Te_132j[l]
143Ce
105Rh
147Nd-147Pm[2]
Half-Life, Days
2.4
0.63
5.2
11.9
3.2
1.4
1.475
11
Principal Gamma
Ray Energy, keV
106
1369
81
164
668
293
319
91
Source
Activation of 238U
Activation of 23Na
Decay of 133I(t1/2 0.87 d)
Decay of 131I(t1/2 8.04 d)
A = 132 decay chain
A = 143 decay chain
A = 105 decay chain
A = 147 decay chain
Note:
These radionuclides are in addition to other fission products identified in the previous and subsequent tables.
[1] The half-life is expressed as that of the parent, 132Te, because they will be in transient equilibrium within about
12 hours of the incident.
[2] These radionuclides represent a no equilibrium case. The half-life is that of 147Nd. The progeny, 147Pm, has a
2.6-year half-life but has very low gamma ray abundance and would likely be detected only after several
months of sample decay using a long count time.
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Table 10A - Analytical Action and Decision Levels (AAL and ADL) and Required Method
Uncertainty Corresponding to Early Phase 1,000-mrem and First Year 2,000-mrem PAG
Values for Fission Products in Soil Using Gross Beta/Gamma Screening Methods
Radionuclide
Ce-141
Ce-143
Ce-144/Pr-144m/Pr-144
Co-60
Cs-134
Cs-137/Ba-137m
1-129
1-131
1-132
1-133
La-140/Ba-140
Mo-99/Tc-99m
Np-239
Nd-147/Pm-147 [2]
Rh-105
Ru-103/Rh-103m
Ru-106/Rh-106
Sr-89
Sr-90/Y-90
Tc-99
Zr-95/Nb-95m/Nb-95
1,000-mrem PAG[1]
AAL
pCi/g
4.4xl05
ADL
pCi/g
2.2xl05
WMR
pCi/g
1.3xl05
2,000 mrem PAG[1]
AAL
pCi/g
7.5xl04
ADL
pCi/g
3.7xl04
"MR
pCi/g
2.3xl04
Activity concentration for this radionuclide is not available.
1.6xl05
1.3xl04
2.0xl04
5.4xl04
l.lxlO6
9.6xl04
4.0xl05
1.6xl05
1.4xl04
1.7xl05
3.1xl05
2.2xl07
8.0xl04
6.5xl03
l.OxlO4
2.7xl04
5.6xl05
4.8xl04
2.0xl05
8.0xl04
7.1xl03
8.5xl04
1.6xl05
l.lxlO7
4.8xl04
3.9xl03
6.1xl03
1.6xl04
3.4xl05
2.9xl04
1.2xl05
4.9xl04
4.3xl03
5.2xl04
9.5xl04
6.6xl06
5900
330
560
1.3xl03
3.5xl04
5.7xl04
7.9xl05
3.1xl05
5.6xl03
2.2xl05
4.3xl05
l.OxlO7
3.0xl03
160
280
660
1.8xl04
2.8xl04
4.0xl05
1.5xl05
2.8xl03
l.lxlO5
2.2xl05
5.2xl06
1.8xl03
100
170
400
l.lxlO4
1.7xl04
2.4xl05
9.3xl04
1.7xl03
6.6xl04
1.3xl05
3.2xl06
Activity concentration for this radionuclide is not available.
6.5xl04
8.4xl04
4.4xl05
2.1xl05
1.2xl07
2.1xl04
3.2xl04
4.2xl04
2.2xl05
l.lxlO5
5.8xl06
l.lxlO4
2.0xl04
2.5xl04
1.3xl05
6.4xl04
3.6xl06
6.5xl03
9.1xl03
2.8xl03
4.9xl04
6.4xl03
4.7xl06
1.9xl03
4.6xl03
1.4xl03
2.5xl04
3.2xl03
2.4xl06
970
2.8xl03
860
1.5xl04
1.9xl03
1.4xl06
590
Notes:
[1] The values in this table for some radionuclides may be different from values shown in previous tables as these
values assume equilibrium between the progenitors and the progeny. The values in the previous tables assume
single radionuclides except where noted.
[2] This is the dose equivalent activity concentration from the 147Pm.
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Table 10B -Analytical Action and Decision Levels (AAL and ADL) and Required Method
Uncertainty Corresponding to Early Phase 1,000-mrem and First Year 2,000-mrem PAG
Values for Fission Products in Soil Using Radionuclide-Specific Methods for
Beta/Gamma Emitters
Ce-141
Ce-143
Ce-144
Co-60
Cs-134
Cs-137
1-129
1-131
1-132
1-133
La-140/Ba-140
Mo-99/Tc-99m
Np-239
Nd-147/Pm-147[2]
Rh-105
Ru-103/Rh-103m
Ru-106/Rh-106
Sr-89
Sr-90/Y-90
Tc-99
Zr-95/Nb-95m/Nb-95
1,000-mrem PAG[1]
AAL
pCi/g
4.4xl05
ADL
PCi/g
3.1xl05
WMR
pCi/g
5.6xl04
2,000 mrem PAG[1]
AAL
pCi/g
7.5xl04
ADL
pCi/g
5.3xl04
WMR
pCi/g
9.4xl03
Activity concentration for this radionuclide is not available.
1.6xl05
1.3xl04
2.0xl04
5.4xl04
l.lxlO6
9.6xl04
4.0xl05
1.6xl05
1.4xl04
1.7xl05
3.1xl05
2.2xl07
l.lxlO5
9.2xl03
1.4xl04
3.8xl04
7.9xl05
6.8xl04
2.8xl05
l.lxlO5
l.OxlO4
1.2xl05
2.2xl05
1.7xl07
2.0xl04
1.6xl03
2.5xl03
6.8xl03
1.4xl05
1.2xl04
S.OxlO4
2.0xl04
1.8xl03
2.2xl04
3.9xl04
2.8xl06
5.9xl03
330
560
1.3xl03
3.5xl04
5.7xl04
7.9xl05
3.1xl05
5.6xl03
2.2xl05
4.3xl05
l.OxlO7
4.2xl03
230
400
930
2.5xl04
4.0xl04
5.6xl05
2.2xl05
4.0xl03
l.SxlO5
3.1xl05
7.4xl06
750
42
71
170
4.5xl03
7.1xl03
l.OxlO5
3.9xl04
700
2.7xl04
5.5xl04
1.3xl06
Activity concentration for this radionuclide is not available.
6.5xl04
8.4xl04
4.4xl05
2.1xl05
1.2xl07
2.1xl04
4.6xl04
5.9xl04
3.1xl05
l.SxlO5
8.3xl06
l.SxlO4
8.2xl03
l.lxlO4
5.5xl04
2.7xl04
l.SxlO6
2.7xl03
9.1xl03
2.8xl03
4.9xl04
6.4xl03
4.7xl06
1.9xl03
6.5xl03
2.0xl03
3.5xl04
4.5xl03
3.3xl06
1.4xl03
l.lxlO3
350
6.2xl03
810
5.9xl05
240
[1] The values in this table for some radionuclides may be different from values shown in previous tables as these
values assume equilibrium between the progenitors and the progeny. The values in the previous tables assume
single radionuclides except where noted.
147T
[2] This is the dose equivalent activity concentration from the Pm.
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
APPENDIX II. EXAMPLE OF HIGH RADIONUCLIDE CONCENTRATION IN SOIL
(RADIOANALYTICAL SCENARIO 1: HIJACKED RESIN SHIPMENT DISPERSED BY
IGNITION)
Description
A shipment of resins used at a nuclear power plant to decontaminate the reactor coolant system
was being transferred from the power plant to a long-term storage facility on May 5. The
shipment contained 750 ft3 of resin estimated to contain over 1,500 curies of mixed radioactive
fission products at the time of the incident. It had been stored at the facility for over 6 years to
allow the level of activity to decay down to a more manageable transport level. The table
identifies the breakdown of the radioactive contaminants contributing most significantly to the
total curies.
Table 11 - Principal Radionuclides Identified in Resins
Radionuclide
Half-Life
Activity, Ci
90Sr
28.8[1J
400
241Am
433 [1J
100
137Cs
30.1 [1J
250
"Tc
2.1xl05[1J
600
Other
Radionuclides[1]
—
150
Total
—
1500
Note:
[1] A mixture of 60Co, 65Zn, 106Ru, 14C, 3H, 1291,241Pu, 238Puand2m240Pu
The 1C has indicated that the ratios of Pu, Pu and Pu isotopes in the source term are
known.
The shipment was hijacked en route, by terrorists. The high integrity containers (HIC) used to
hold the radioactive materials were opened by drilling holes in the outer shell and charges of C4
explosive were implanted into the HIC. The charges on the HIC were detonated in an open field.
This caused a spread of resins in an area of about 1 acre. The field was set ablaze with gasoline.
The meteorological conditions during the 134 hours of active burning and smoldering of the field
were steady wind from the SSW at 4-11 mph (6-18 kph), no precipitation, and average daily
temperature of 81 °F (27 °C). Soil samples in several downwind and upwind directions are being
collected to assess the spread and extent of contamination. The incident command has decided
that the soil samples are to be analyzed for first year exposure PAG values (e.g., the first year
2,000 mrem AAL is 330 pCi/g for 60Co, and 6,400 pCi/g of 90Sr and 930 pCi/g 239Pu). All values
should be reported on a dry weight soil basis in pCi/g. Samples that are screened and found to be
above that level based on screening results are to be analyzed first and all other samples held in
suspense until further notice.
Event Sequence
It is Day 7 of the event. The incident responders have established a field office for coordinating
response efforts including a laboratory project manager. At 1000 hours of Day 7, the incident-
response team sends the laboratory five, 320 gram soil samples taken from the affected area
downwind of the burn area that have been field screened at significantly above background
radiation levels. The samples arrive at the laboratory at Day 8, 1300 hours. A 24-h turnaround
time has been requested.
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Analysis Paths
Step 1. Sample receipt screening uses a micro-R meter. Laboratory personnel perform an initial
screen of the sample shipping container prior to opening it. The contact reading at the surface of
the transport container is 4 mR/h. The sample transport container is moved to a mini-hot-cell.
The sample containers are removed from the transport container, and assessed for external
contamination using standard swipe techniques. None are externally contaminated.
Day 8, 1330 hours
Step la. Each container has approximately 320 g of soil. Containers are counted for gross
gamma for 1 minute each on a shielded 3x3" Nal(Tl) detector. The lower level discriminator is
set at 50 keV and all counts up to 2000 keV will be captured as gross gamma activity.
A 2-g aliquant of each sample is transferred to a liquid scintillation vial with cocktail and
counted with a wide open window without discrimination between alpha or beta. It is recognized
that the risk of false non-detection of analyte, and the measurement uncertainty for a 2-gram
subsample of unprocessed, unhomogenized soil will be high. Still, this test can provide important
indications about the overall activity of samples under the plume and will be used to help make
decisions about safe handling and contamination control.
Day 8, 1400 hours
Steps 2a and 2b. Example results of screening analysis for gamma and gross alpha/beta are
shown in Table 12.
Table 12 - Results of Screening Analysis for Soil Samples
Container ID
1
2
3
4
5
Background, (± la)
Total counts,
Nal(Tl) detector
28,830
1,167,550
110
543,550
2,047,550
30 ±6
Gross cpm
Liquid Scintillation
Counter
142
1,352
32
1,782
3,892
12 ±2
60,
The Nal(Tl) detector has been calibrated using a Co standard in 320 grams of soil in the same
type of container in which samples are received and has an efficiency of 31%. The background is
30 counts for a 10 minute count time. The sample activities (± CSU, k=\) estimated are shown
here:
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Sample 1:
pCi (28,830 - 30) counts
Gross gamma,— = = 131 (+ 33) pCi/g
5 g (0.31 x 1 minute x 320 g x 2.22) v~ JV /5
Sample 2: 5,300 (± 1,300) pCi/g
SampleS: 0.36 (± 0.10) pCi/g
Sample 4: 2,470 (± 620) pCi/g
SampleS: 9,300 (± 2,300) pCi/g
9/11
The liquid scintillation counter was calibrated for single channel analysis with a Am standard
QO QO
and yielded an efficiency of 4.5%, and with a Sr/ Y soil standard and yielded a beta efficiency
of 9.5%. Due to high quench, samples were not counted in alpha/beta discriminating mode. The
lower of the two efficiencies was used to conservatively minimize the risk of underestimating
measured activities.
Following the removal of detritus and sub-sampling, a 2-g aliquant is suspended in 15 mL of a
gelling liquid scintillation cocktail and counted for 10 minutes on the LSC. This yields a gross
activity concentration (± CSU, k=l) for total alpha plus beta of:
Sample 1: Gross Alpha + Beta Activity,^- = [142 cpm ~12 cpm] = 650 pd/g
Q U-UTO X Z (^f X Z.ZZ
Sample 2: 6,700 pCi/g
SampleS: lOOpCi/g
Sample 4: 8,800 pCi/g
SampleS: 19,000 pCi/g
In Steps 2a and 2b, samples are to be assessed based on the alpha/beta, and gamma results.
All samples meet the MQO for required method uncertainty for gross gamma (i.e., 100 pCi/g at
or below the AAL of 330 pCi/g, or less than 31% above the AAL). Due to the small aliquant of a
potentially non-homogenous sample, there is significant risk that uncertainty estimates will not
adequately reflect the non-representative aliquant, and that alpha- and beta-emitter activity
present in the sample might go unidentified. Although gross alpha and beta results will not be
used to make any final decision about whether an AAL has been exceeded, this data will be used
to make decisions about handling and processing samples (i.e., priority and minimizing the risk
of contamination and cross-contamination). Comparing gross alpha and beta results based on a
small aliquant against the gross gamma results based on the entire sample may show indications
of potential non-homogeneity.
The measured combined standard uncertainty is less than the required method uncertainty, and
the measured sample activity for samples 2, 4, and 5 are above the gross gamma ADL of 160
pCi/g (based on the limiting case of 60Co). These samples are put on the red path to Step 3. The
combined alpha/beta for sample 1 is above the limiting ADL for combined gross alpha+beta
activity of 210 pCi/g so it is also placed on the red path to Step 3. Sample 3 falls below the ADL
for both gross gamma and gross alpha +beta and is placed on the green path to Step 2b. In Step
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
2b both the sum of the gross gamma and gross alpha+beta activity is less than the limiting ADL
of 210 pCi/g and sample 3 is relegated to the lowest priority yellow path.
Results of both screens indicate that samples 1, 2, 4 and 5 are of higher yet similar enough
activity levels that they may be processed together using elevated levels of contamination
control. The gross alpha+beta activity parallels the gross gamma activity and does not provide
any preliminary indications of issues with potential gross non-homogeneity. The gross gamma
activity is somewhat greater than the gross alpha+beta indicating the possible presence of pure
alpha, beta, or low-energy emitters or in the samples.
The time is Day 8, 1500 hrs.
Step 3. The soil contains twigs and stones greater than about 1/21' in diameter. These are removed
with the aid of a stainless steel forceps and probe and set aside as there has yet to be direction on
how to address an activity concentration in these materials. There is considerable moisture and
organic content to the soil. The samples are individually coned and quartered into two 160 gram
fractions.
Working quickly, the volatile fraction is isolated and transferred to an air-tight sample container
to minimize the loss of volatile radionuclides. The non-volatile fraction is transferred to a tared
half-liter paint can. The non-volatile samples are placed in a drying oven at 110+10 °C.
The time is Day 8, 1525 hours
Step 4a, Samples 2, 4, and 5.
After the samples have dried to constant weight, percent solids are calculated for each sample for
correction of "as-received" aliquants to "dry-weight" aliquants in Steps 6 and 7b. Stainless steel
balls are added to each paint can and the cans are shaken for about 5-10 minutes to mill and
homogenize the samples to solids that conform to the visual size standard. Aliquants for each
radionuclide-specific test are transferred to crucibles. Additional aliquants are set up without
tracers for gross alpha and beta screening in Step 7. Quality controls are also set up for each
batch, and appropriate tracers and carriers added to all sample aliquants. The crucibles are
transferred to a furnace where a ramped program is used to incrementally raise the temperature
to -600 °C to remove all organic materials.
The time is Day 8, 1550 hours.
Step 4b, Samples 2, 4, and 5.
Samples are aliquanted for gamma spectral analysis from the volatile fraction isolated in Step 3.
Working quickly to minimize losses, the sample is mixed in the container and 75 mL of "as
received" soil is transferred to a tared container matching calibrated gamma geometry and
sealed. The sample is weighed to determine the net mass of the "as received" aliquant.
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Representative 1-gram aliquants are taken from the mixed sample for analysis of volatile
radionuclides. Based on general knowledge about the source term, analyses performed will be
for 129I and 99Tc. Quality controls are also set up for each batch and all samples spiked with
appropriate tracers and carriers. Samples are digested using the validated methods that minimize
losses to volatilization for each of these radionuclides.
The dry-weight equivalent for each of the volatile radionuclide aliquants is calculated by
applying the percent solids determined in Step 4a. This "dry-weight" aliquant will be used to
calculate gamma results on a dry-weight basis in Steps 6 and 7b.
The time is Day 8, 1625 hours.
Step 5a, Samples 1, 2, 4, and 5.
The samples dried and oxidized in Step 4a are dissolved using a sodium carbonate fusion
technique. The melt is redissolved in hydrochloric acid and visually inspected to verify that
complete dissolution of the solids was obtained.
The time is Day 8, 1945 hours
Step 5b, Samples 1, 2, 4, and 5.
The samples aliquanted in Step 4b are digested using a basic wet digestion technique. The
product of the dissolution is visually inspected to verify that complete dissolution of the solids
was obtained.
The time is Day 8, 1800 hours
Step 6, Samples 1, 2, 4, and 5. The samples prepared for gamma analysis in Step 4b are counted
5 cm from the surface of the HPGe detector for approximately 30 minutes to meet the limiting
first year 2,000 mrem MQO for required method uncertainty for 60Co of 42 pCi/g at the AAL of
330 pCi/g. The detector used is calibrated for the same 75-mL geometry in which the samples
are counted. As the samples count, the 59.5 keV gamma ray for 241Am is identified, and the most
abundant characteristic gamma ray from 241Pu is present but with low very peak area. Although
there is high uncertainty, these both tentatively indicate the presence of Pu isotopes in the
sample. Since the 1C has indicated that the ratios of Pu isotopes in the source term are known, the
more complex and time intensive analysis for 241Pu will not be required.
The "dry-weight" equivalent is entered into analysis software as the sample aliquant since results
will be reported on a "dry-weight" basis. Following the count, all unidentified peaks in the
spectrum with a standard uncertainty less than 50% are identified and added to the library if they
will significantly impact final quantitation of results.
The time is Day 8, 1725 hours
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Step 7, Samples 1, 2, 4, and 5.
Aliquants of the sample set up for gross alpha and beta screening in Steps 4a and 4b are analyzed
for gross alpha and beta on a liquid scintillation counter. Given the smaller size of the aliquants
and the cleaner matrix after dissolution, alpha beta discrimination is practicable. The liquid
scintillation counter has been optimized to reliably detect low levels of alpha activity in the
presence of elevated beta activity by using a longer discriminator time setting for the pulse shape
discriminator (longer than the cross-over point) to minimize beta-to-alpha crosstalk. The LSC is
calibrated with pure 238Pu (since other isotopes of Pu present in 239Pu mixtures interfere with
cross-talk measurements) and with 90Sr/90Y standards. The dissolved melt from the fusion is
taken to dryness and redissolved in 1 mL of 0.1 M nitric acid. 19 mL of liquid scintillation
cocktail are added, the vial is capped, shaken, and the samples counted for 5 minutes each. The
results of the screen are listed in Table 13.
Table 13 - Results of Screening Analysis for Soil Samples
Sample ID
1
2
4
5
Gross Alpha Activity
(pCi/g dry-weight)
44 ±30
1,000 ±260
1,330 ±340
2,910 ±730
Gross Beta Activity
(pCi/g dry-weight)
191 ±53
5,400 ±1,300
7,100 ±1,800
15,500 ±3,900
All four gross alpha and beta results satisfy the MQO for required (relative) method uncertainty
(based on limiting ADLs 239Pu and 60Co in Tables 6A and 6B). All four samples have combined
alpha+beta activities that exceed the limiting ADL for screening, so they continue on the red path
to Step 7a.
The time is Day 8, 2045 hours
Step 7a, Samples 1, 2, 4, and 5.
941
Although Am was identified by the gamma spectral analysis, it still will be determined by
alpha spectrometry due to the possibility of bias for the low-energy 59.5 keV gamma ray.
Samples are aliquanted for the Pu and Am analysis. The results of gross alpha and gross beta
screening indicate, however, that a reduced aliquant for sequential analysis of Am and Pu
isotopes will be necessary to prevent the tracer from being overwhelmed by analyte, and to
minimize the risk of contamination of the detector. The size of aliquant containing -50 pCi of
alpha is calculated from the gross alpha results. Samples 2, 3 and 5 are diluted to a known
volume of 100 mL in dilute hydrochloric acid and 50, 1, 20 and 0.5 mL aliquants are taken,
respectively. Since the amount of tracer originally added to the samples prior to dissolution is no
longer be sufficient to produce the minimum number of tracer counts needed for the yield
determination, an additional 60 dpm 236Pu and 243Am tracers is added to each aliquant. The tracer
activity used for calculations is adjusted to reflect the total of original and added tracer present in
the samples. The lower activity aliquants are then processed using a validated rapid sequential
method for Pu and Am analysis.
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Although the late addition of tracer is not optimal, chemical separations have yet to be performed
and the dissolution process should be near quantitative as run, so there should be little impact on
the data quality. Still, the need to perform the dilution and replenish tracer in the samples will be
clearly noted in the case narrative.
The time is Day 9, 0145 hours
Step 7b, Samples 1, 2, 4, and 5. The product of the sample dissolutions from Step 5b is taken
for analysis using validated rapid methods of 99Tc and 129I.
The time is Day 9, 0200 hours
Step 8, Samples 1, 2, 4, and 5. Each set of results is reviewed to ensure that the correct process
was followed, that all manual data entry is accurate, that all QC criteria are met, results are
appropriately qualified, and that all anomalous situations or deviations from standard operating
procedures are narrated. These results are approved by the laboratory supervisor.
The analytical results from the samples are shown in Table 14 in units of pCi/g, dry weight.
Table 14 - Results of Radionuclide Specific Analysis in Soil Samples
Sample
1
2
3
4
5
2,000
mrem ADL
2,000
mrem ML
241Am
39
310
—
4,680
7,000
780
1,100
238pu
—
20
—
75
80
720
1,000
239t240p|J
24
205
—
800
1,000
660
930
Total a
Activity
63
535
—
5555
8,080
—
—
a
fraction
0.1
0.5
—
2.1
2.9
—
—
90Sr
45
1,000
—
1,100
3,800
4,500
6,400
90y30
45
1,000
1,100
3,800
n/a
n/a
"Tc
0
580
—
400
2,600
3.3x106
4.7x106
60Co
41
900
—
150
1,250
230
330
137Cs
52
1,160
—
330
4,700
930
1,300
129|
99
2,200
—
100
1,500
2.5x104
3.5x104
Total
P + Y
activity
327
7,840
—
4,280
21,450
—
—
P + Y
fraction
0.2
3.8
—
0.9
8.0
—
—
Sum of
Fractions
>1.0
N
Y
—
Y
Y
—
—
Results are evaluated to determine whether AAL values have been exceeded based on individual
radionuclide results (as batches of data are completed). The MQO for required method
uncertainty has been met for all analyses. Based on individual results, one or more values for
either an alpha or gamma emitter is greater than the ADL in samples 2, 4, and 5 and it is
concluded that the respective AALs have been exceeded. The 1C is notified of the preliminary
results while the remaining analyses proceed to completion (broken line to Step 11).
The time is Day 9, 0230 hours
Step 9, Samples 2, 4, and 5. The total a and P+y activity columns represent the sum of all the
activities from those radionuclide groupings. The sum of the radionuclide-specific results is
30 Assumes secular equilibrium of 90Y with 90Sr. Note that the derivation of AAL values for 90Sr assume secular
equilibrium with decay progeny (see Table 6B).
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
compared with the original gross gamma and final alpha beta screen by LSC screening results to
ensure that major contributors to dose have not been overlooked.
1 9Q
Note that I does not contribute to the gamma sum since it decays by electron capture and its 30
keV X-rays are below the threshold of the gross gamma ray analysis. Low-energy radiation does
provide some response in the LSC analysis. Assuming that 129I was not lost during oxidation of
the sample, its activity may be added to the beta-gamma total. It is also assumed that 90Y is
present in secular equilibrium with 90Sr although this may or may not be the case shortly after the
incident.
When the values in Table 14 are compared to those in Table 13 for the screening results, the
sums of radionuclide specific activities of (alpha + beta) or gamma are within a factor of two of
their respective screening results. It is concluded that no major emitters have been overlooked.
The time is Day 9, 0245 hours
Step 10, Samples 1, 2, 4, and 5. Once all data is complete and reviewed, the sum of the fractions
(i.e., the "unity rule") is calculated for all radionuclides in each sample. The sum of the fractions
for all radionuclides in samples 2, 4, and 5 exceed unity it is concluded that the first year at 2,000
mrem AAL has been exceeded. In sample 1, the sum of the fractions calculation indicates that
the AAL has not been exceeded.
No radionuclide-specific analysis has been done for sample 3. it will be analyzed for
radionuclide specific activity at a later date once all higher priority samples have been analyzed.
The time is Day 9, 0300 hours
Step 11, Samples 2, 4, and 5. Any residual materials from the original sample, the dried or
dissolved residues from the dissolution, and the sample test sources, are archived in case other
analyses are necessary in the future. A concise report and case narrative with the analytical
values and their associated uncertainties is sent to the 1C.
The time is Day 9, 0315 hours
Step 12, Samples 3. At this time, sample screening results identifies sample 3 as below the
2,000-mrem AAL. It is stored and will be sent through the complete analytical scheme when
analytical capacity permits.
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APPENDIX III. EXAMPLE OF SOILS ANALYZED TO ASSESS THE EXTENT OF
CONTAMINATION (RADIOANALYTICAL SCENARIO EXAMPLE 2: SOIL ANALYSIS
IN THE RECOVERY PHASE FOLLOWING AN ROD)
Description31
During the recovery phase following the detonation of an RDD, the environs around the
detonation site and beyond will be evaluated for radioactive contamination. For this scenario, the
priority switches from high priority for high-activity samples (clearly contaminated) to high
priority for low-activity samples (indicating zones that may be uncontaminated). Thus, samples
are screened for gross gamma, alpha, and beta radioactivity based on first-year 1CT4 risk-based
action levels. Those samples having gross radioactivity concentrations below the 10 4 risk-based
action levels have priority for specific radionuclide analyses. The radionuclide contaminants that
initiated the incident have largely been characterized by now under Radioanalytical Scenario 1,
and their results lead into the specific radioanalytical processes. However, it is possible that these
samples may have other radionuclide contaminants, either related to the initial incident or from
naturally-occurring sources, which will need to be characterized. Again, it is important to
emphasize that the priority flow path for this scenario is set up in the reverse of Radioanalytical
Scenario 1: the high-priority flow path is for those samples that have low activity concentration.
1Q9
The micro-R meter used in the receipt screening of the samples has been calibrated with an Ir
source as this has been identified as the principal gamma-emitting radionuclide.
Event Sequence
On May 3 an RDD was detonated in a metropolitan area. Attribution sample analyses have
QO 9^R 1Q9
confirmed that the device contained Sr, Pu, and Ir as the major contaminants. It is Day 30
following the event and the recovery phase is ongoing. The Incident Command Center has
dispatched three soil samples that need to be assessed for contamination levels acceptable for re-
habitation.
The time frame for results is not as critical as in Radioanalytical Scenario 1 but prompt
identification of "clean" areas (areas deemed by the 1C to be re-habitable based on first year 10~4
risk) is important in rebuilding public confidence in the cleanup effort. The only radionuclides
that have been identified above background in any of the contaminated samples in or outside the
blast zone are 238Pu, 192Ir, and 90Sr. The three samples arrive at the laboratory at 0800 on Day
31.
Analysis Paths
Step 1. Sample receipt involves screening using a micro-R meter. Laboratory personnel perform
an initial screen of the transport container prior to opening it. The contact reading at the surface
of the transport container is 140 |iR/h. The sample transport container is moved to a laboratory
hood so that the sample containers may be individually assessed for dose.
31 Radioanalytical Scenario Example 2 is unrelated to Radioanalytical Scenario Example 1.
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The three samples are individually surveyed as they are removed from the transport container,
using a micro-R meter, yielding the following results for total dose (Table 15).
Table 15 - Screening Results for Soil Samples Following an IND
Sample
Container
(iR/h
Container
1
65 ±5
Container
2
25 ±4
Container
3
100 ±6
Instrument
Background
15±3
The sample containers are also assessed for external contamination using standard swipe
techniques. None of the containers are found to be externally contaminated.
Step 2. Each container has approximately 500 g of soil. The soil contains twigs and stones
greater than about 1A" in diameter. These are removed with the aid of stainless steel forceps and a
probe and are reserved as there has yet to be direction on how to address activity contained in the
twigs or stones. There is considerable moisture and organic content to the soil.
Each sample is counted for 1 minute on a shielded 3x3" Nal(Tl) detector. The detector's lower
level discriminator is set at 50 keV and all counts up to 2000 keV will be captured as gross
gamma activity and referenced to 192Ir. The results of the screening analysis for gross gamma are
shown in Table 16.
Table 16 - Results of Gross Gamma
Analysis of Soil Samples
Container ID
1
2
3
Background, (± la)
Total counts,
Nal(Tl) detector
10,254
8,298
48,139
40 ±6
The Nal(Tl) detector has been calibrated in a geometry conforming to the full sample container
and has an efficiency of 0.375 counts per disintegration when using a 500-g soil matrix
192
containing Ir.32 The sample activities are estimated as shown here:
Sample 1: Gross Gamma,— =
(10,254-40)
(2.22x0.375x500^)
= 24.5 ± 6.1 pd/g
Sample 2:
Sample 3:
19.8±5.0pCi/g
116±29pCi/g
Although the lowest ADL in Table 7B is for 60Co at 9.8 pCi/g, 60Co has not been identified as a
contaminant so it is not considered limiting. In this case the screening results are compared to the
MQOs and ADL value for 192Ir (the sole gamma emitter). The required method uncertainty is 56
pCi/g at the AAL of 180 pCi/g. The ADL is 92 pCi/g.
32 The only gamma-ray emitter expected in samples from this event is 192Ir.
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1Q9
MQOs for required method uncertainty are met for all samples. The conclusion is made that Ir
is not present above the AAL in samples 1 and 2 since their activity is less than the ADL. Sample
3, however, shows activity above the screening ADL for 192Ir.
Since those areas that are "clean" are the priority, this sample is archived to be analyzed if
needed at a later date. Samples 1 and 2 will need to be analyzed for 192Ir by HPGe gamma
spectrometry in Step 6.
Step 3. Samples land 2. The samples are individually coned and quartered. Two 125-g fractions
of bulk sample are isolated during coning and quartering. The fraction isolated for non-volatile
analysis is transferred to a tared 1-pint paint can. A second portion is transferred to a container
for "as-received" analyses. The unused half of the sample is archived.
Step 4a. Samples land 2. The steel can containing the 125-gram "non-volatile" fraction is
placed in an oven at 110 ± 10 °C and the sample dried to 'constant weight. Percent solids are
calculated as the ratio of the dry-weight mass to the pre-drying "as-received" mass of sample.
This will be applied to convert "as-received" aliquants to "dry-weight" aliquants in Steps 6 and
7b.
Stainless steel balls are added to each paint can containing the dried sample and the cans are
shaken for about 5-10 minutes to mill and homogenize the samples to solids that conform to the
visual size standard.
A representative aliquant of dried, milled, and homogenized sample is taken for gross alpha and
beta screening prior to aliquanting samples for dissolution. About 70-120 mg of homogenized
solid will be transferred to the textured surface of a "sticky" swipe applied to a stainless steel
planchet using the adhesive backing of the swipe (i.e., cloth-side facing up). The swipe plus
planchet are tared. The same paint can used for drying, pulverizing and storing the sample has an
opening marginally smaller than 2" in diameter. The 2" diameter planchet (containing the swipe)
fits neatly into the groove for the lid sealing the opening of the can. By shaking the can
containing the pulverized solids and tapping the planchet to remove loose solids from the surface
of the swipe, a small amount of solid is quickly transferred to the swipe with minimal use of
equipment and relatively low risk danger of cross-contamination.
Before they are removed from the hood, the sample test sources are checked for elevated levels
of radioactivity using a handheld survey meter. The planchet, swipe, and solid are weighed to
determine the net amount of sample on the planchet for activity calculations. The solids are then
fixed to the planchet by applying a very light layer of hair spray. The planchet is dried for a
minute under a heat lamp and reweighed to determine the mass to use for self-absorption
corrections.
Step 4b. Samples land 2. The planchet is counted on a gas flow proportional counter dedicated
to screening samples that have low to slightly elevated levels of radioactivity. The results of the
alpha/beta screen are calculated applying corrections for crosstalk, efficiency and the dry-weight
aliquant. The screen results with associated combined standard uncertainty are reviewed and are
presented in Table 17.
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Table 17 - Results of Gross Alpha and Beta Analysis of Soil Samples
Container ID
Sample 1
Sample 2
Gross Alpha
pCi/g, dry weight
20.7 ±6.1
16.4 ±5. 8
Gross Beta
pCi/g, dry weight
14.1 ±7.4
16.1 ±7.9
Since there is only one pure alpha and one pure beta emitter, and neither of them is volatile, the
results of the alpha and beta screen can be used to determine whether the activity of 238Pu and
90Sr is below the respective AALs and can potentially be used to eliminate the need for
radionuclide-specific testing. Table 7a shows that the WMR for screening for 238Pu is 18 pCi/g at
the AAL of 60 pCi/g, with an ADL of 30 pCi/g. Similarly for gross beta screening for 90Sr, WMR is
110 pCi/g at the AAL of 380 pCi/g, and the ADL is 190 pCi /g. None of these results exceed
those values and samples land 2 are all kept on the hot path for the alpha- and beta-emitting
radionuclide-specific analyses.
Step 4c. Samples land 2. One-gram aliquants of milled homogenate are transferred to nickel
crucibles for plutonium and radiostrontium analysis. Quality controls are set up for each batch,
and tracers and carriers added to sample aliquants as required by each of the procedures being
run. The crucibles are transferred to a furnace where a ramped program is used to incrementally
raise the temperature to -600 °C to remove all organic materials. The plutonium and strontium
samples are dissolved using a sodium carbonate fusion technique. The melt is redissolved in
hydrochloric acid and visually inspected to verify that complete dissolution of the solids was
obtained.
Step 5a. Sample land 2. Although no volatile constituents were identified in the attribution
analysis, the volatile fraction will be used to prepare the sample for gamma spectral analysis. It is
thoroughly mixed and a representative 75-mL volume of the sample is transferred to a tared
counting container for which there is a calibrated geometry on the gamma spectrometer. The
filled container is reweighed and the "as received" aliquant mass calculated. Since all results
must be reported on a dry-weight basis in Steps 6 and 7b, the "as-received" mass will be
converted to "dry-weight" equivalent by applying the percent solids determined in Step 4a.
Step 6, Sample land 2 The sample prepared for gamma analysis in Step 5a is counted above the
endcap of the HPGe detector for approximately 30 minutes to meet the first year 10"4 risk-based
MQO for required method uncertainty for l 2Ir of 56 pCi/g at the AAL of 180 pCi/g. The
detector used is calibrated for the same 75-mL geometry in which the samples are counted. As
the samples count, it is noted that no other gamma rays except for those from 192Ir, and low-
levels of natural radionuclides in the background soil, are present.
Step 7a, Samples land 2. After completion of the dissolution techniques, the dissolved samples
are processed for 238Pu using the laboratory's validated procedures.
Step 7b, Samples land 2. After completion of the dissolution techniques, the dissolved samples
are processed for total radiostrontium using the laboratory's validated procedures.
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Step 8, Samples land 2. Each set of results is reviewed to ensure that the correct process was
followed, that all manual data entry is accurate, that all QC criteria are met, required method
uncertainties have been met, results are appropriately qualified, and that all anomalous situations
or deviations from standard operating procedures are narrated. The analytical results along with
the associated combined standard uncertainty for the samples are shown in Table 18 in units of
pCi/g, dry weight. These results are approved by the laboratory supervisor.
Table 18 - Results of Soil Analysis Following an RDD
Sample
1
(Radiochemical)
1 (Screen)
2
(Radiochemical)
2 (Screen)
3
(Radiochemical)
3 (Screen)
First year 10~4
ADL
First year 10~4
AAL
192jr
39 ±4.29
24
32 ±3.52
20
238pu
0.6 ± 1.0&
20
3.7± 1.2
16
90Sr Sy
6.2 ±2.8 39
14
8.1 ±3.3
16
—
32
—
Sa
0.6
—
3.7
—
spt
51.3
—
48.2
—
Sum of
Fractions
0.25
—
0.26
—
Not Analyzed
[116±29]%
130
180
—
43
60
—
270
380
—
—
—
'Gross gamma results
&Result less than critical level - not considered when comparing screen and radionuclide-specific results
fThe gross beta results include activity from 90Y assumed to be in secular equilibrium with the 90Sr
Step 9, Samples land 2. Individual results are compared to the respective ADLs as they are
completed. All MQOs are met and no results exceed 10^ risk ADLs.
Step 10, Samples land 2. The £ columns are the simple sums of the individual a, (3, or y
activities. These are compared with the original screening values by gross gamma and final LSC
screen. Gross alpha is greater than the 238Pu results for samples 1 and 2. The alpha and beta data
from Samples 1 and 2 are reviewed again (Step 8) to check for errors and no issues are
identified. The gamma ray results for sampes 1 and 2 compared well with the screening results.
The discrepancy between the screen and radionuclide-specific results is consistent with typical
levels of naturally-occurring radioactive materials in soils, however, so a notation is made in the
case narrative and the data are reported without further qualification.
Step 11, Samples 1 and 2. The sum of the fractions is calculated for samples 1 and 2. The gross
gamma results that demonstrated in Step 2 that 192Ir was not present in samples above the AAL
1 Q9
are substituted for the radionuclide-specific results when calculating the SOF since Ir could be
present at those levels in samples. If the SOF had exceeded unity for either of these two samples,
however, a determination would have to be made if samples should be sent back for radionuclide
specific analysis (in the case of gamma, Step 6) to determine the actual concentration of 192Ir
present.
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Because the SOF does not indicate that the AAL have been exceeded, the results for these two
samples are reported to incident command.
Step 13, Samples 1, 2, 3. All sample residuals, digests and sample test sources are archived for
potential future analysis.
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APPENDIX IV. EXAMPLE OF SOILS ANALYZED FOLLOWING AN IND INCIDENT
(RADIOANALYTICAL SCENARIO EXAMPLE 3)
Description33
An IND detonation spreads contamination in the form of fission products with a minor
contribution of activation products and TRU elements. Some initial fissile material that did not
undergo fission is likely present as paniculate matter and it is anticipated that this material will
be in the form of DRPs. The initial samples from the blast zone are sent for attribution analysis.
Fission products are negatron and gamma-ray emitters. Screening using a micro-R meter will
provide a good measure of the degree of contamination from the fission products but probably
not for any of the TRU elements. Thus, gamma screening will be used as the primary tool for
determining contamination controls. The determination of gross alpha is left until later in the
analysis sequence.
Additionally there are many fission, activation, and TRU radionuclides that result from such an
event that have half-lives measured in hours to a few days. This means that the screening results
will change rapidly as a function of time. Several notable parent-progeny relationships exist for
transient or secular equilibrium, which will create some difficult calculation issues. The
analytical results for these radionuclides will require review by someone knowledgeable in these
relationships and the capabilities of the detection systems used. These pairs are found in Tables
10A and 10B along with their AAL values.
Event Sequence
An IND was detonated four days ago in an urban setting on the Atlantic Seacoast. Immediately
following the event a nor'easter hit the area of the blast zone spreading the contamination over a
wider area up and down the Eastern Seaboard as well as inland for about 150 miles.
The Incident Command Center has dispatched five 200-g soil samples that need to be analyzed
so that isopleths of contamination can be established to help facilitate recovery efforts. The time
frame for results is critical as rehabitation of large suburban areas need to be made. The focus is
to identify the most contaminated samples. First year 1,000 mrem PAG AAL, ADL and WMR
values apply.
The samples arrive at the laboratory at 0800 on Day 4.
Analysis Paths
Step 1. Five samples (all placed in 200-mL plastic containers filled to the top, compacted with
hand pressure and the lids sealed on top with duct tape) have arrived, all of which have been
determined by the field sampling teams to be significantly above background radiation levels.
33Radioanalytical Scenario Example 3 is unrelated to Radioanalytical Scenario Examples 1 and 2.
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The laboratory staff has a specific-sample geometry for their micro-R meter so that each
individual sample can be scanned for gross gamma contamination as it arrives using a 10-second
pass through a shielded chamber. This is sufficient to meet the MQO for required method
uncertainty for 60Co. Although 60Co is not anticipated to be a major contributor, its ADL value of
6.5><103 pCi/g is conservatively selected to identify samples that will need additional, prompt
radiochemical analysis. The conversion factor that is being used for the dose reading is based on
a 200 g soil sample with a 60Co standard homogeneously distributed within it. The factor is 175
Table 19 identifies the samples received, their measured dose rates and estimates of the
equivalent gamma activity referenced to 60Co.
Table 19 - Initial Gamma Dose Rate Survey in Soil Following an IND
Sample ID
LiR/h
PCi/g
A680
60 ±5
4,550
A685
460 ± 35
74,550
A702
395 ±35
63,300
A719
746 ± 45
124,600
A736
250 ±15
37,800
Background
34 ±3
—
Step 2. All samples have screening results that are greater than 6.3xl03 pCi/g except for A680.
That sample is archived for analysis at a future time. The remaining samples are put on the fast
path for immediate analysis.
The 1C is notified that samples A685, A702, A719, and A736 will be analyzed first as their
initial gamma screening results place them in the high activity concentration category,
potentially challenging the AALs. Sample A680 is to be archived until analysis of the first
samples is underway.
Step 3. Each container has approximately 200 g of soil. The soil contains twigs and stones
greater than about 1/21' in diameter. The samples are processed individually with the aid of a
stainless steel forceps and probe to remove any detritus. The detritus is set aside to be analyzed
separately if required by the analytical protocol specified in the project plan.
Care should be used (both from the personal exposure and analytical cross-contamination
standpoint) when isolating non-soil like materials as it is possible that these materials, like the
soil, may contain hot particles (DRPs) of TRU oxide from the original IND device.
The soil samples have considerable moisture and organic content. They are individually coned
and quartered.
Step 4. The samples from each of the containers are dried at about 110 °C. After constant weight
has been achieved (and the dry-weight basis determined), the dried samples are put into a pint
paint can with some stainless steel balls and shaken for about 5 minutes to mill and homogenize
the samples.
Aliquants are removed from this homogenate and spiked with Sr carrier for radionuclide-specific
analysis. Three times the normal Sr carrier is added since the sample will be split in three
following dissolution. The samples are transferred to a furnace where the temperature is raised
using a program to -600 °C to remove all organic materials. Aliquants for each sample are taken.
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Step 5. The aliquants from each of the samples that was dried and oxidized in Step 4 is
placed into nickel crucibles, and each is dissolved using a validated sodium carbonate fusion
technique. The samples are dissolved in an HC1 solution following the cool down of the melt
from the fusion. Separate aliquants are taken for analysis in Steps 8a and 9.
Step 6. The "as-received" sample is mixed well and a 75-mL aliquant of each sample is
transferred to a counting container for which there is a calibrated gamma geometry. Gamma
analysis proceeds at Step 7.
Step 7. Each sample is counted for 15 minutes 7.5 cm from the endcap of an HPGe gamma
spectrometer to meet MQOs for required method uncertainty for 60Co. The analysis will
determine all gamma emitters, volatile and non-volatile. The gamma spectrometric results are
tabulated in Table 20.
Table 20 - Results for Gamma Spectrometry in Soil Samples Following an IND
Radionuclide m
95Nb
95Zr
"Mo
99mTc
131j
132J
133j
137Cs
14aBa
140La
239Np
A685
pCi/g
62 ±7
1.2xl03±65
1.2xl04±400
1.0xl04±500
2.3xl03±240
730 ± 40
630 ±29
2.3xl04±1100
1.5xl04±800
1.3xl04±710
1.7xl03±120
A702
pCi/g
72 ±7
1.43xl03±70
1.42xl04±420
1.20xl04±580
3.4xl03±300
840 ± 50
730 ±37
1.4xl04±800
1.9xl04±900
1.5xl04±790
550 ±48
A719
pCi/g
110 ±12
2.2xl03±100
2.2xl04±750
1.8xl04±900
5.3xl03±390
1.3xl03±80
1.2xl03±65
2.2xl04±1000
2.8xl04±1200
2.3xl04±1100
2.9xl04±1200
A736
pCi/g
50 ±4
937 ±43
8.20xl03±260
7.78xl03±390
2.25 x!03± 200
479 ±35
488 ±25
8.00 ±490
1.17xl04±570
1.06xl04±500
293 ±32
Step 8a. Gross alpha will be measured to determine if plutonium, americium or uranium analysis
are necessary. Since gross alpha measurements on gas proportional counters operating in
simultaneous counting mode, or on liquid scintillation counters operating in pulse-shape or pulse
decay counting mode, will be overwhelmed by high levels of beta into alpha crosstalk.
Therefore, the gross alpha samples will be counted on a gas proportional counter operating at the
alpha voltage.
An aliquant of the dissolved sample from Step 5 is treated with concentrated nitric acid to
remove chlorides, evaporated to dryness, and quantitatively transferred to a planchet. The
samples are counted for 30 minutes each to meet MQOs for required method uncertainty for
9^Q r-*-,
Pu of 410 pCi/g at the AAL of 1,300 pCi/g. The gross alpha activities for each of the samples
are shown in Table 21.
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Table 21 - Results for Gross Alpha
in Soil Following an IND
Sample ID
A685
A701
A719
A736
Gross Alpha
Activity ± CSU
pCi/g
720 ± 130
418 ±78
265 ± 42
251±41
Step 8b. Gross alpha screening results for Step 8a are assessed to see if they exceed the 239Pu
AAL of 1,300 pCi/g. All results satisfy the MQO for required method uncertainty at the AAL.
Only sample A685 exceeds the gross alpha screening ADL of 670 pCi/g. An aliquant of this
sample is taken for sequential alpha spectrometric analysis in Step 8c.
Step 8c. The initial attribution analyses for the event indicate that this was a 239Pu device. The
941
elevated gross alpha activity in sample A685 indicates that Pu, and Am analyses need to be
performed. Plutonium and americium analyses are begun shortly after strontium analysis is
commenced using an aliquant of the fused sample.
The size of the aliquant is reduced to minimize the likelihood that the tracer will be overwhelmed
by analyte, and to keep the levels of activity introduced into alpha spectrometers as low as
possible. The plutonium analysis is run with 236Pu tracer which is not easily overwhelmed by
high levels of 239+240Pu. These radionuclide-specific flow paths use rapid methods that produce
analytical results within 24 hours. The results of these analyses are shown in Table 22. Note that
the U results showed a negligibly small contribution to both the total activity and the SOF/dose
and are not included here.
Table 22 - Results for Isotopic Am and Pu in Soil Following an IND
Radionuclide'11
239+240pu 34
238Pu
241Am
A685
pCi/g
480 ±41
32 ±4
75 ±4
A702
pCi/g
430 ±12
29 ±4
190 ±9
A719
pCi/g
280 ±10
14 ±2
85 ±4
A736
pCi/g
332 ±11
17±2
110 ±9
Step 9. The only significant beta-only emitters that need analysis are 89Sr and 90Sr. An aliquant
of the dissolved melt from Step 5 is used to start analysis for both these radionuclides. This step
is done in parallel with Steps 7 and 8a. The 89Sr and 90Sr activity concentration are shown in
Table 23.
34 The results of plutonium analysis using alpha spectrometry can only provide a result which is the sum of the two
activities for 239Pu and 240Pu. This is because their alpha peaks are too close together to be resolved. By convention
the sum of the two activity contributors will be compared to the ADL and AAL for 239Pu.
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Table 23 - Results for BUSr and HBSr in Soil Following an IND
Radionuclide [11
89Sr
90Sr
A685
pCi/g
410±35
2.6 ±0.4
A702
pCi/g
740 ± 56
5.3 ±0.7
A719
pCi/g
1070 ± 92
6.7 ±0.8
A736
pCi/g
499 ±38
3.3 ±0.5
Step 12. Each set of results is reviewed to ensure that the correct process was followed, that all
manual data entry is accurate, that all QC criteria are met, required method uncertainties have
been met, results are appropriately qualified, and that all anomalous situations or deviations from
standard operating procedures are narrated. The analytical results along with the associated
combined standard uncertainty for the samples are shown in Table 24 in units of pCi/g, dry
weight. These results are approved by the laboratory supervisor.
Table 24 - Summary and Evaluation of Results for Soil Samples Following an IND
Radionuclide
89Sr
9osr
95Nb
95Zr
"Mo
99mjc
131|
132|
133|
137Cs
140Ba
i40|_a
239Np
238pu
239+240 pu
241 Am
A685
pCi/g
410 ±35
2.6 ±0.4
62 ±7
1.2x103±65
1.2x104±400
1.0x104±500
2.3x103±240
730 ±40
630 ±29
2.3x104±1100
1.5x104±800
1.3x104±710
1.7x103±120
32 ±4
480 ±41
75 ±4
SOF Total
Gamma total
(pCi/g)
Dose rate
survey(pCi/g)
Sum of
isotopic alpha
(PCi/g)
Gross Alpha
(pCi/g)
8.1x104
7.5x104
587
720 ±130
Fraction
ofAAL
9.3x10-4
1.2x10-5
—
0.057
0.071
—
0.024
1.8x10-3
3.9x10-3
0.43
1.07
—
5.5x10-3
0.021
0.37
0.044
2.1
A702
pCi/g
740 ± 56
5.3 ±0.7
72 ±7
1.43x103±70
1.42x104±420
1.20x104±580
3.4x103±300
840 ±50
730 ±37
1.4x104±800
1.9x104±900
1.5x104±790
550 ±48
29 ±4
430 ±12
190 ±9
8.3x104
6.3x104
649
418 ±78
Fraction
ofAAL
1.7x10-3
2.5x10-5
—
0.068
0.084
—
0.035
2.1X10-3
4.6x10-3
0.26
1.4
—
1.8x10-3
0.019
0.33
0.11
2.3
A719
pCi/g
1070 ±92
6.7 ±0.8
110±12
2.2x103±100
2.2x104±750
1.8x104±900
5.3x103 ±390
1.3x1 03 ±80
1.2x103 ±65
2.2x104±1000
2.8x104±1200
2.3x104±1100
2.9x104±1200
14±2
280 ±10
85 ±4
1.5x105
1.2x105
379
265 ± 42
Fraction
ofAAL
2.4x10-3
3.2x10-5
—
0.10
0.13
—
0.055
3.2x10-3
7.0x10-3
0.41
2.0
—
0.094
0.093
0.22
0.050
3.2
pCi/g
499 ± 38
3.3 ±0.5
50 ±5
937 ±43
8.20x103±260
7.78x1 03±390
2.3x103 ±200
479 ±35
488 ±25
8.0x103 ±490
1.17x104±570
1.05x104±500
293 ±32
17±2
332 ±11
110 ±9
5.2x104
3.8x104
459
251 ±41
Fraction
ofAAL
1.1X10-3
1.6x10-5
—
0.045
0.048
—
0.023
1.2x10-3
3.0x10-3
0.15
0.84
—
9.4x10-4
0.011
0.25
0.060
1.4
Steps 13 and 14. The sum of the individual results compares favorably with the screening results
and no additional action is required for these samples.
90
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Step 15. The results from the analyses completed in Steps 7, 8b, 8c, and 9 are compared to their
respective ADL values in Tables 6C, 6D, and 10B.
The comparison shows that that the measured result for 140Ba exceeded the ADL for three of the
four fast track samples. This means that the 1,000-mrem AAL concentration for that radionuclide
has been exceeded at the tolerable error selected for the MQO. However, the AAL concentration
assumes that the 140Ba is in equilibrium with its progeny 140La. Based on the results of the
laboratory analysis, it is apparent that equilibrium has not yet been achieved. Equilibrium, when
achieved, will yield an activity ratio of 140La/140Ba of approximately 1.2. This means that the
activity of the combination will increase over the next several days until maximum is achieved.
Thus the conclusion is conservative for the time of analysis. This fact is noted in the case
narrative to the 1C.
The calculation of the fractional AAL for each radionuclide, as well as the sum of fractions
(SOF) for all radionuclides, are shown in Table 24. The SOF for all four of the samples exceeds
unity. Note even if the 140La/140Ba pair were not part of the analytical results (i.e., not detected
above the critical level) that the sum of fractions for the remainder of the radionuclides would
yield values greater than one for two of the four samples even though individually each
radionuclide would be less than its AAL value.
Step 16. The results in Table 24 are transmitted to the 1C indicting that these four samples
exceed the AAL values
Step 17. The samples are archived, and the sample that was found to have screening values less
than the ADL is now analyzed. The information from the high activity concentration samples are
used to assess both sample size and count times for these lower activity concentration samples.
91
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
APPENDIX V. REPRESENTATIVE ANALYTICAL PROCESSING TIMES
Sample receipt
and debris
removal
1 hr
3 hrs
\
i
Removal of
aliquant for
volatiles
analysis
Coning and
quartering
Dry to remove
water
Volatiles by
Gamma
Spectrometry
8 hrs
NOTE: If gross alpha/beta
screen results in a non-
detect, radionuclide specific
analysis is not needed.
Start Gamma
Spectrometry
10 hrs
13 hrs
18 hrs
38 hrs
40 hrs
Aliquant
combustion
completed
Start 89Sr and
90Sr analysis
89Sr and 90Sr
completed
Assessment of
all results
Aliquants
removed for
fusion
Aliquant fusion
completed
Gross alpha of
soil by GPC
I
A.
Aliquant of
Dissolved, fused
soil- use rapid
methods for TRU
Alpha
Spectrometry
completed
Figure 7 - Analytical Processing Timeline for Soil Sample Following an IND
92
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
APPENDIX VI. ESTABLISHING DQOS AND MQOS FOR INCIDENT RESPONSE
ANALYSIS
Three distinct radioanalytical scenarios are presented for soil potentially contaminated with
radionuclides. The first two assume that the mixture of radionuclides in the sample is unknown.
In the third situation, the result of an IND, the radioactive contaminants are known (fission
products). In each scenario there is special emphasis on the implementation of the decision trees
presented within that scenario for prioritizing sample processing by the laboratory. This
emphasis on the decision trees is to support timely decisionmaking by the 1C regarding actions to
protect human health and to expedite analysis so that decisions made to support the data quality
objectives can be made with confidence. Specific MQOs associated with the flow diagrams in
Figures 2, 3, and 4 are given in Tables 23, 24, and 25.
This appendix covers single-sample screening measurement decisions by the laboratory. The 1C
may need to make decisions based on the final radionuclide-specific concentrations based on the
mean of the set of samples taken from an area. MQOs would need to be developed separately for
this case. The required method uncertainty (um) should be smaller in this case compared to the
laboratory's screening decisions, perhaps by a factor of three (see MARLAP Appendix C).
Is the
'parameter of"
Yes / interest greater \ No
9
The flowcharts depicted in this document contain
decision points. There are three basic symbols on
these flowcharts: rectangles, which represent
activities or tasks; decision point diamonds, which
represent decision points; and arrows, which
represent flow of control. In these flow diagrams, \ ,.an . e ,
. r ,. , , , , . . . ' \ action level
there are many diamond-shaped decision points.
Most often they are of the form shown in Figure 8.
This is the general form of a theoretical decision rule
as discussed in Step 5 of the DQO process. The Figure 8 - Decision Symbol Used in Flow Diagrams
parameter of interest usually is the "measurand" of the radiochemical analysis being performed
(e.g., concentration of a radionuclide, total activity concentration, etc.). The AALs will have
been set according to criteria involving the appropriate PAGs. The arrows specify the alternative
actions to be taken.
The DQO process may be applied to all programs involving the collection of environmental data
with objectives that cover decisionmaking activities. When the goal of the study is to support
decisionmaking, the DQO process applies systematic planning and statistical hypothesis testing
methodology to decide between alternatives. Data quality objectives can be developed using
EPA (2006) Guidance on Systematic Planning Using the Data Quality Objectives Process (EPA
QA/G-4).
The DQO process is summarized in Figure 9 and Table 19. From this, MQOs can be established
using the guidance in MARLAP. The information in Table 19 should be sufficient to enable the
decisionmaker and laboratory to determine the appropriate MQOs. The output should include an
AAL, discrimination limit, gray region, null hypothesis, analytical decision level (ADL, referred
to in MARLAP as "critical level"), and required method uncertainty at the AAL. A table
93
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
summarizing DQO process for each decision point diamond can be prepared in advance and
summarized as shown in Tables 20 and 21.
Step 1. State the Problem.
Define the problem that necessitates the study;
identify the planning team, examine budget, schedule.
I
Step 2. Identify the Goal of the Study.
State how environmental data will be used in meeting objectives and
solving the problem, identify study questions, define alternative outcomes.
Step 3. Identify Information Inputs.
Identify data and information needed to answer study questions.
Step 4. Define the Boundaries of the Study.
Specify the target population and characteristics of interest,
define spatial and temporal limits, scale of inference.
Step 5. Develop the Analytic Approach.
Define the parameter of interest, specify the type of inference,
and develop the logic for drawing conclusions from findings.
r
Decisionmaking
(hypothesis testing)
1
Estimation and other
analytic approaches
1
Step 6. Specify Performance or Acceptance Criteria.
Specify the probability limits for
false rejection and false
acceptance decision errors.
Develop performance criteria for new data
being collected or acceptable criteria for
existing data being considered for use.
1 F
Step 7. Develop the Plan for Obtaining Data.
Select the resource-effective sampling and analysis plan
that meets the performance criteria.
Figure redrawn from EPA G-4 (2006).
Figure 9 - The Data Quality Objective Process
94
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Table 25 - The DQO process Applied to a Decision Point
STEP
Step 1 . Define the problem
Step 2. Identify the decision
Step 3. Identify information
needed for the decision
Step 4. Define the boundaries
of the study
Step 5 . Develop a decision
rule.
This defines the decision
point diamond.
OUTPUT
. . . with a preliminary determination of the type of data needed and
how it will be used; identify decisionmaker.
...among alternative outcomes or actions, and a list of decision
statements that address the problem.
Analytical action levels that will resolve the decision and potential
sources for these; information on the number of variables that will
need to be collected; the type of information needed to meet
performance or acceptance criteria; information on the performance of
appropriate sampling and analysis methods.
Definition of the target population with detailed descriptions of
geographic limits (spatial boundaries); detailed descriptions of what
constitutes a sampling unit timeframe appropriate for collecting data
and making the decision or estimate, together with any practical
constraints that may interfere with data collection; and the appropriate
scale for decisionmaking or estimation.
Identification of the population parameters most relevant for making
inferences and conclusions on the target population; for decision
problems, the "if..., then... else..." theoretical decision rule based upon
a chosen AAL.
The theoretical decision rule specified in Step 5 can be transformed into statistical
hypothesis tests that are applied to the data. Due to the inherent uncertainty with
measurement data, there is some likelihood that the outcome of statistical hypothesis
tests will lead to an erroneous conclusion, i.e., a decision error. This is illustrated in
Table 20.
Table 26 - Possible Decision Errors
Decision Made
Decide that the parameter of interest is
greater than the action level.
Decide that the parameter of interest is
less than the action level.
True Value of the parameter of interest
Greater than the action level
Correct decision
Type II Decision Error
Less than the action level
Type I Decision Error
Correct decision
In order to choose an appropriate null hypothesis (or baseline condition), consider which
decision error should be more protected against. Choose the null hypothesis that, if falsely
rejected, would cause the greatest harm. Then the data will need to be convincingly inconsistent
with the null hypothesis before it will be rejected, and the probability of this happening (a Type I
error) is more easily controlled during the statistical design. Failing to detect a sample that
exceeds the AAL could have consequences to public health. But screening additional samples
will slow the overall process and therefore also may impact the public health. The probability
that such decision errors occur is defined as the parameters a and ft in Steps 6.1 and 6.2 in Table
21. Values of alpha and beta should be set based on the consequences of making an incorrect
decision. How these are balanced will depend on the AAL, sample loads, and other factors as
95
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
specified by the 1C. The most commonly used values of alpha and beta are 5%, although this is
by tradition and has no sound technical basis. These values may be used as a default, but should
be optimized in Step 7 of the DQO process according to the actual risk of the decision error
being considered.
Table 27 -The DQO Process Applied to a Decision Point
STEP
Step 6. Specify limits on
decision errors
Step 6.1 Determine
analytical action level
(AAL) on the gray
region boundary and set
baseline condition (null
hypothesis, H0)
6.2 Define the
discrimination limit
(DL)
6.3 Define the required
method uncertainty at
the AAL
Step 7. Optimize the
design for obtaining data
OUTPUT
Which is considered the worse: decision error (a) deciding that the parameter of
interest is less than the AAL when it actually is greater, or (b) deciding that the
parameter of interest is greater than the AAL when it actually is less? Case (a) is
usually considered to be a conservative choice by regulatory authorities, but this
may not be appropriate in every case.
If (a), the AAL defines the upper boundary of the gray region. The null
hypothesis is that the sample concentration is above the AAL. (All samples will
be assumed to be above the AAL unless the data are convincingly lower.) A
desired limit will be set on the probability (a) of incorrectly deciding the sample
is below the AAL when the sample concentration is actually equal to the AAL.
If (b), the AAL defines the lower boundary of the gray region. The null
hypothesis is that the sample concentration is below the AAL. (All samples will
be assumed to be below the AAL unless the data are convincingly higher.) A
desired limit will be set on the probability (6) of incorrectly deciding the sample
is above the AAL when the sample concentration is actually equal to the AAL.
If (a), the discrimination limit defines the lower boundary of the gray region. [1 ] It
will be a concentration below the AAL where the desired limit will be set on the
probability (a) of incorrectly deciding the sample is above the AAL.
If (b), the discrimination limit defines the upper boundary of the gray region. [2] It
will be a concentration above the AAL where the desired limit will be set on the
probability ((3) of incorrectly deciding the sample is below the AAL.
According to MARLAP Appendix C, under either case (a) or case (b) above, the
recommended required method uncertainty is:
where z^a and ZI_B are the \-a and \-B quantiles of the standard normal
distribution function. Values ofz^-a (or z\_p) for some commonly used values of a
(or /?), taken from tables of the cumulative normal distribution (EPA 2009), are
shown in Table 22.
Iterate Steps 1-6 to define optimal values for each of the parameters and the
measurement method required.
Notes:
[1] The discrimination limit (DL) is the point where it is important to be able to distinguish expected signal from
the AAL. When one expects background activity, then it might be zero. If one expects activity near the AAL,
however, it might be at 90% of the AAL.
[2] The DL is the point where it is important to be able to distinguish expected signal from the AAL. If the AAL is
near zero, the DL would define a concentration deemed to be too high to be undetected. Thus, the DL may be
set equal to the minimum detectable concentration (MDC). If one expects activity near the AAL, however, it
might be at 110% of the AAL.
96
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
if
°-
0.9-
0.8
0.7
0.6-
0.5-
0.4
0.3-
0.2
0.1-
0
Grav Region
RelatJvdv
DMdfln Frrar
sre C
Tolciahlc'
n Decision
FjTM" Rllll**
20 40 60 80 100 120 140 160 180 200)
, Wion Lrvri
I rue v.i i; of the Parameter (Mean Concentration, ppm)
if
-
Sfa!
— >
0 20 40 61) SI 11*1 1211 140 USD IMl 21X1
True Value of flic raramrtrr Ofcau (i „,„•,, i,:, i M .11.! r 111
Figure 10 - Example Illustrating Case (a) Baseline
Condition (null hypothesis): Parameter Exceeds the AAL
Figure 11 - Example Illustrating Case (b) Baseline
Condition (null hypothesis): Parameter does not
Exceed the AAL
See Table 27, Step 6.1. Figures 10 and 11 takenfromEPA QA/G-4 (2006).
Figures 10 and 11 illustrate the concepts above for case (a) and case (b) respectively. In Figure
10, the AAL = 100, the DL = 80, A = 100 - 80 = 20 a =fi = 0.1 and
<
20
(1.282 + 1.282)
= 7.8
In Figure 11, the AAL = 100, theDL= 120, A = 120-100 = 20 a = p = 0.1 and
A 20
UMR <
(z1_a+z1_/?) (1.282 + 1.282)
= 7.8
Table 28 - Values of z1 a (orz1 J for Some
Commonly Used Values of a or
a or ft
0.001
0.01
0.025
0.05
0.10
0.20
0.30
0.50
ZI_K (or z^)
3.090
2.326
1.960
1.645
1.282
0.842
0.524
0.000
The concentration that indicates the division between values leading to rejecting the null
hypothesis and those that do not is termed the "critical level." Possible values of the
concentration can be divided into two regions, the acceptance region and the rejection region. If
97
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
the value of the concentration comes out to be in the acceptance region, the null hypothesis being
tested is not rejected. If the concentration falls in the rejection region, the null hypothesis is
rejected. The set of values of a statistic that will lead to the rejection of the null hypothesis tested
is called the critical region. Critical region is a synonym for rejection region. In the context of
analyte detection, the critical value (MARLAP 2004, Attachment 3B.2) is the minimum
measured value (e.g., of the instrument signal or the analyte concentration) required to give
confidence that a positive (nonzero) amount of analyte is present in the material being analyzed.
The critical value is sometimes called the critical level.
In case (a), the critical value (or "Analytical Decision Level" - ADL) will be UBGR - z^ UM,
where UM is its combined standard uncertainty of the measurement result, x. Only measurement
results less than the critical value will result in rejecting the null hypothesis that the true
concentration is greater than the AAL. This process can be completed for each diamond in each
flowchart to fill in Tables 29, 30, and 31. In these tables, values have been rounded to 2
significant figures.
In case (b), the critical value (ADL) will be LBGR + z^ WM, where UM is its combined standard
uncertainty of the measurement result, x. Only measurement results greater than the critical value
will result in rejecting the null hypothesis that the true concentration is less than the AAL.
In the following tables, MQOs were determined for screening using a discrimination level of
zero and Type I and Type II error rates of a = ft = 0.05. These are the MQOs usually associated
with developing MDCs and result in a relative method uncertainty of 30% at the AAL, and an
ADL value of 0.5 times the AAL. For radionuclide-specific measurements the requirements are
more stringent, using a discrimination level of one-half the AAL and Type I and Type II error
rates of a = 0.01 with/? = 0.05. These result in a relative required method uncertainty of 13% at
the AAL and an ADL value of 0.71 times the AAL. Note that gamma spectrometric
measurements using an HPGe are always radionuclide-specific, and therefore have the more
stringent MQOs.
98
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Table 29 - DQOs and MQOs for Radioanalytical Scenario 1. Laboratory Prioritization
Decisions Based on Screening (Gross a, p, ory) and Radionuclide-Specific
Measurements
S s
Measurem
RectanglOC
1a
1a
1a
1a
-
-
-
d
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CD
Q
'o
Q_
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2a
2a
2a
2b
7
7
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cf
to"
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<
03
§:
a
V
P
a + B +
M
V
a
P
V
-S5
o
i
"CD
o
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d
410
330
3200
590
See Table
6A
See Table
6B
See Table
6Cand6D
— I c~)
2s "" —
o V CO
^ O °
CD d
1|
I "03
3- E
0.30
0.30
0.30
0.30
0.30
0.30
0.13
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03 -
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d Q
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03 03
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210
160
1600
290
0.50xML
0.50xML
0.71 xML
$
"5
03
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1
E "oT
03 ^
1 &
li
< LZ
Notes:
[1] All calculated values are rounded to two significant figures.
[2] The value of 590 pCi/L is derived from, 160(gross gamma) +210 (gross alpha) +220 (lowest ADL for a beta only
emitter 227Ac). The 227Ac is used since there is a potential for this being an IND type scenario.
Table 30 - DQOs and MQOs for Scenario 2. Laboratory Prioritization Decisions Based on
Screening (Gross a, p, or y and Radionuclide-Specific Measurements)
03
O)
-g
Q?
d
03
to
3
^
2
4a
7a
7b
7c
d
o
CD
Q
"c
o
'to
%
Q
3
4b
9
9
9
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cf
to
i-
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Q.
|
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aandp
a
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20
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See Table
7C
See Table
7D
See Table
7D
to ° °
r^- ^P ' — ~
^ o to
= o
^ -^ m
"Z. O •
a
a
a
a
a
-o
CD
CD O
s s
( (
-------
Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
Table 31 - DQOs and MQOs for Radioanalytical Scenario 3. Laboratory Prioritization
Decisions Based on Screening (Gross a, p, ory) and Radionuclide Specific
Measurements
CD
O3
£=
CD
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1
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8c
9
7
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CO
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1
£=
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2
8b
15
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See
Table 6C
See
Table 6D
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Table
10B
ML or
, case (a) or a
Z O — :
a
a
a
a
a
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-. — -. —
8 8
s s
£= £=
1 1
V A
Q Q
a
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a
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a
QL
o
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•<
13,000
1,300
0.5xML
0.5xML
0.5xML
3e 1 error rate <
>,
0.05
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0.01
0.01
0.01
00.
3e II error rate
>,
0.05
0.05
0.05
0.05
0.05
s
3
3,900
390
0.13xML
0.13xML
0.13xML
S-
0.30
0.30
0.13
0.13
0.13
s
CD jf
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d £j
CD "CD
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<£ Q-
6,500
650
0.71 xML
0.71 xML
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urce of ML
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<=> m
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•«~ CD
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1
Notes:
[1] All calculated values are rounded to two significant figures.
[2] The gamma screening ADL is derived from the AAL 60Co.
[3] The alpha screening ADL value is derived from the AAL of 239Pu. Pu-239 represents a radionuclide that would
either be part of the IND or would be formed as a result of neutron capture on 238U.
100
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Radiological Laboratory Sample Analysis Guide for Incident Response - Radionuclides in Soil
APPENDIX VII. NET COUNT RATE AND COUNTING TIMES FOR TYPICAL
NUCLEAR INSTRUMENTATION USED FOR RAPID ANALYSES (EXAMPLE) - 10"
AND KT6 RISK
Table 32 - Net Count Rate and Counting Times for Typical Nuclear Instrumentation Used
for Rapid Analyses (Example) - IQ^and 10"6Risk
Radionuclide
241 Ami1!
241Am
243Cm[1]
243Cm
239pu [1]
239pu
226Ra[1]
226Ra
238y [1]
238U
^CePi
60CO PI
228Ra[2]
228Ra
89Sr[2]
89Sr
Sample
Size,
g
1
2
1
2
1
2
1
2
1
2
250
250
1
2
1
2
ML 1(H
Risk,
pCi/g
65
65
75
75
55
55
24
24
240
240
350
20
47
47
290
290
UMR,
pCi/g
3.5
3.5
9.7
9.7
7.1
7.1
3.2
3.2
31
31
46
2.5
6.1
6.1
38
38
Count
Time,
(min)
4
2
4
2
4
2
9
5
1
<1
<1
<1
3
2
<1
<1
AAL10-6
Risk,
pCi/g
0.65
0.65
0.75
0.75
0.55
0.55
0.24
0.24
24
24
3.5
0.20
0.47
0.47
2.9
2.9
UMR,
pCi/g
0.035
0.035
0.097
0.097
0.071
0.071
0.032
0.032
0.31
0.31
0.46
0.025
0.061
0.061
0.38
0.38
Count
Time,
(min)
350
180
310
160
430
220
1000
500
100
50
4
40
very long
520
80
30
Notes: A 7% relative standard uncertainty is assumed for the other standard uncertainties such as for a tracer or a
gamma efficiency curve.
[1] Alpha spectrometry radionuclides assumptions: detector efficiency of 0.24; chemical yield of 0.70; abundance/
branching ratio of 1.0; background count rate of 0.005 cpm; background counting time of 1,000 min.
[2] Beta only radionuclide assumptions: detector efficiency of 0.40; chemical yield of 0.70; abundance/branching
ratio of 1; background count rate of 1.0; background counting time of 1,000 min.
[3] Gamma radionuclides assumptions: detector efficiency, 60Co - 0.035 and 144Ce - 0.12; branching ratio, 60Co -
1.0 and 144Ce - 0.108; background count rate, 60Co - 1 cpm and 144Ce - 5 cpm; background counting time of
100 min.
101
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