EPA/600/R-18/243 | May 2019
www.epa.gov/homeland-security-research
United States
Environmental Protection
Agency
oEPA
Radiological Emergency:
Exposure Assessment of
Livestock Carcass Management
Office of Research and Development
Homeland Security Research Program
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Radiological Emergency:
Exposure Assessment of Livestock Carcass Management
U.S. Environmental Protection Agency
Office of Research and Development
Homeland Security Research Program
Cincinnati, OH 45268
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Disclaimer
The U.S. Environmental Protection Agency (EPA) through its Office of Research and
Development), in collaboration with the United States Department of Homeland Security funded
and managed the research described here under Interagency Agreement HSHQPM13X00157 and
contract No. EP-C-14-001 to ICF under WA 24. It has been subjected to the Agency's review
and has been approved for publication. Note that approval does not signify that the contents
necessarily reflect the views of the Agency. Numeric results in this assessment should not be
interpreted as "actual" risks. Any mention of trade names, products, or services does not imply
an endorsement by the U.S. Government or EPA.
Questions concerning this document, or its application should be addressed to:
Paul Lemieux, Ph.D.
National Homeland Security Research Center
Office of Research and Development
U.S. Environmental Protection Agency
109 TW Alexander Drive E343-06
RIP, NC 27711
Phone: 919-541-0962
Fax: 919-541-0496
E-mail: lemieux.paul@epa.gov
or
Sandip Chattopadhyay, Ph.D., M.B.A. *
National Homeland Security Research Center
Office of Research and Development
U.S. Environmental Protection Agency
26 W. Martin Luther King Drive, MS NG16
Cincinnati, OH 45268
Phone: 513-569-7549
Fax: 513-487-2555
E-mail: chattopadhyay. sandip@epa.gov
* Now employed by U.S. EPA's Office of Chemical Safety and Pollution Prevention; 1200
Pennsylvania Avenue, NW; Washington, DC 20460; 202-564-4806 (Phone)
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Table of Contents
Disclaimer ii
List of Tables v
List of Figures vi
Acknowledge ments vii
Executive Summary viii
Acronyms and Abbreviations xi
1. Introduction 1
1.1. Purpose and Scope 1
1.2. Report Organization 2
2. Problem Formulation 2
2.1. Radiological Incident Scenario 2
2.2. Radionuclides of Concern 4
2.2.1. Measures of Radiation Emissions and Exposures 4
2.2.2. Selected Radionuclides of Concern 5
2.3. Livestock Carcass Management Options 7
3. Exposure Estimation 10
3.1. Initial Carcass Contamination 10
3.2. Releases to Environmental Media 12
3.2.1. Burial 12
3.2.2. Composting 14
3.3. Fate and Expo sure Modeling 16
3.3.1. Leaching from Burial Trenches and Composting Windrows 16
3.3.2. Concentrations in Surface Soil 20
3.4. Exposure Estimation 21
3.4.1. Human Health Benchmarks 21
3.4.2. Exposure Metrics 25
4. Results and Discussion 26
4.1. Base Case Exposure Assessment 26
4.1.1. Groundwater Pathways 26
4.1.2. Soil Pathways 31
4.2. Uncertainty Analysis 31
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4.2.1. Scale of Mortality 31
4.2.2. Level of Contamination 34
4.3. Exposure Assessment Summary 36
4.4. Uncertainty Summary 41
5. Quality Assurance 48
6. Literature Cited 49
Appendix A: Conceptual Models 1
Appendix B: Additional Radionuclide Exposure Information 1
IV
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List of Tables
Table ES. 1. Qualitative Ranking of Livestock Carcass Management Options - Containment vs.
Treatment Options x
Table 1. Measures of Radioactivity and Exposure 5
Table 2. Accidents at Nuclear Power Plant—Past Examples 6
Table 3. Radionuclides Included in the Exposure Assessment 7
Table 4. Livestock Carcass Management Options Considered for the Exposure Assessment 7
Table 5. Highest Radiocesium Detections by Prefecture 11
Table 6. Initial Radionuclide Activity Levels in Livestock Carcassa 11
Table 7. Assumptions for the Burial Management Option 13
Table 8. Estimated Radionuclide Activity in Leachate from Burial3 14
Table 9. Assumptions for the Composting Management Option 15
Table 10. Estimated Radionuclide Activity in Finished Compost3 for Four Contamination Levels
16
Table 11. Base Case Radionuclide Activity Concentrations in Well Water with Burial of 100
Carcasses 18
Table 12.134Cs Radionuclide Activity Concentrations in Well Water with Burial of Increasing
Numbers ofCarcasses3 18
Table 13. Radionuclide Activity Concentrations in Well Water with Increasing Time Between
Leaching and Water Use, Base Case Burial Option3 19
Table 14. Base Case Radionuclide Activity Concentrations in Well Water with Composting of
100 Carcasses 19
Table 15. Estimated Radionuclide Activity in Finished Compost, Base Case 21
Table 16. Overall Limits (Emergency and Non-emergency) for Human Exposures to Radiation22
Table 17. Radionuclide Activity Concentrations for Maximum Contaminant Level (MCL)
Compliance (USEPA 2002) 23
Table 18. Slope Factors for Radionuclide Ingestion 24
Table 19. Preliminary Remediation Goals for Radionuclides (PRGs) Calculated for Groundwater
Exposure 24
Table 20. Compost Application Areas for Calculating Soil Preliminary Remediation Goals for
Radionuclides (PRGs) 25
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Table 21. Preliminary Remediation Goals for Radionuclides (PRGs) Calculated for Soil
Exposure 25
Table 22. Ranking Ratios with the Base Case3 27
Table 23. Contribution of Groundwater Exposure Pathways to Preliminary Remediation Goals
for Radionuclides (PRGs) 31
Table 24. Base Case Ranking Ratios for Soil Exposure Pathways Following Compost
Application 33
Table 25. Ranking Ratios with Increasing 134Cs Contamination 34
Table 26. Ranking Ratios with Increasing 137Cs Contamination 35
Table 27. Ranking Ratios with Increasing 90Sr Contamination 35
Table 28. Ranking Ratios with Increasing 131I Contamination 35
Table 29. Qualitative Ranking of Livestock Carcass Management Options - Containment vs.
Treatment Options 38
Table 30. Moderate to High Natural Variation in Parameter—Potential Bias from Selected
Values 42
Table 31. Uncertainty in Parameter Value(s) Selected 43
Table 32. Simplifying Assumptions—Effects on Exposure Estimates 45
List of Figures
Figure 1. Groundwater exposure ranking ratios for burial and composting by scale of mortality,
with Maximum Contaminant Level (MCL) benchmark 28
Figure 2. Groundwater exposure ranking ratios for burial and composting by scale of mortality,
with Preliminary Remediation Goals for Radionuclides (PRG) benchmark (adult, drinking water
only) 29
Figure 3. Groundwater exposure ranking ratios for burial by scale of mortality, with Preliminary
Remediation Goals for Radionuclides (PRG) benchmark 30
VI
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Acknowledgements
The following individuals and organizations have been acknowledged for their contributions
towards the development and/or review of this document.
United States Environmental Protection Agency (EPA)
Sandip Chattopadhyay, Ph.D., M.B.A. (Principal Investigator)
Sarah Tail, Ph.D.
Paul Lemieux, Ph.D.
Eletha Brady-Roberts (Quality Assurance Reviewer)
Robert G. Ford, Ph.D.
United States Department of Agriculture (USDA), Animal and Plant Health Inspection Service
(APHIS)
Lori P. Miller, P.E.
ICF
Joshua Cleland
Kaedra Jones
Margaret McVey, Ph.D.
United States Department of Homeland Security (DHS) Science and Technology Directorate,
Chemical and Biological Defense Division
Michelle M. Colby, D.V.M., M.S.
General Dynamics Information Technology
Marti Sinclair
External Peer Reviewers
Gary Flory (VA DEQ)
Robert Miknis (USDA/APHIS)
Gordon S. Cleveland (USDA/APHIS)
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Executive Summary
Proper management of livestock carcasses following large-scale mortalities protects humans,
livestock, and wildlife from chemical and biological hazards; maintains air, water, and soil
resources; protects ecological resources and services; and enhances food and agricultural
security. In support of the National Response Framework, the U.S. Department of Homeland
Security (DHS) Science and Technology Directorate funds research in collaboration with the
U.S. Environmental Protection Agency's (USEPA's) Office of Research and Development,
Homeland Security Research Program, and the U.S. Department of Agriculture's (USDA's)
Animal and Plant Health Inspection Service (APHIS) to support the proper management of
animal carcasses following major environmental incidents. Mass livestock mortalities can result
from a natural disaster, foreign animal disease outbreak, chemical or radiological incident, or
other large-scale emergencies. As a product of the collaborative research between USEPA and
USDA, this report evaluates livestock carcass management options following a radiological
emergency through a comparative exposure assessment. This assessment helps to inform a
scientifically-based selection of environmentally protective methods in times of emergency.
Preceding phases of this project assessed exposures following natural disasters, foreign animal
disease outbreaks, and chemical emergencies.
A radiological emergency affecting livestock could be unintentional (e.g., nuclear facility or
other nuclear accidents, accidental feed contamination) or intentional (e.g., criminal or terroristic
acts). The radiological incident scenario for this assessment includes beef cattle that have
ingested feed contaminated by fallout from a nuclear power plant accident. Four radionuclides of
concern and initial contamination levels for the assessment are based on data from actual nuclear
power plant accidents.
The livestock carcass management options considered in the human exposure assessment are the
seven well-established methods included in the previous phases of this project: on-site open
burning (pyre), on-site air-curtain burning, on-site unlined burial, on-site composting, off-site
fixed-facility incineration, off-site landfilling, and off-site carcass rendering.
For the three off-site options, all environmental releases are assumed to be adequately controlled
and monitored in compliance with applicable U.S. federal regulations. Because few facilities are
licensed to manage radioactive wastes in the U.S., capacity, cost, and long travel-distances are
likely to eliminate these from consideration for managing large volumes of radioactive carcasses.
In addition, the assessment assumes that rendering would not be used because radioisotopes
would remain in products and waste streams, all of which would require further management as
radioactive wastes. For these reasons, radiological exposures associated with the off-site options
are not quantitatively assessed.
Combustion-based carcass management options, including off-site incineration, on-site open
burning, and on-site air-curtain burning, might not change the quantity, the level of radioactivity,
or the rate of radioactive decay of radioisotopes significantly. These options, especially the
uncontrolled on-site options, will release some quantity of radioisotopes to air causing further
spread of contamination. Exposures are not assessed for the two on-site combustion options.
VIII
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Exposures are quantitatively assessed for leaching to groundwater from on-site burial trenches
and compost windrows, and from soil exposure pathways from compost application. Exposures
are evaluated relative to one another based on ratios of estimated radionuclide activity
concentrations in media to risk-based benchmarks. Potential exposures from groundwater are
greater for the burial option than the composting option. This is due to the absorption of leachate
by bulking material in the windrow, which reduces leaching to the ground below. For both
groundwater and soil contamination, potential exposures are affected by radioactive decay rates
and the amount of time before exposure occurs.
Table ES.l summarizes rankings of the seven carcass management options. The rankings are
based primarily qualitative analysis, because two of the on-site options, as well as the three off-
site options, were not quantitatively assessed. Two groups of carcass management options are
ranked in the first column of Table ES.l. Rank 1 (i.e., options least likely to result in exposure)
applies to the three containment options: off-site landfilling, burial, and composting. These
options do not destroy radioactivity; they are intended to reduce or prevent the release and
dispersal of radionuclides from the carcasses. The four treatment options (i.e., off-site
incineration, rendering, air-curtain burning, and open burning) receive Rank 2. They do not
destroy radioactivity, but they might spread or worsen contamination at the carcass management
site. In Table ES.l, the options in each ranking group are listed in descending order from least to
most likely to result in radiation exposures based on the scenarios assessed in this report.
This report provides information to compare options and support decision-making in the event of
actual radiological emergencies. In addition to the exposure assessment findings, it provides a
scientifically based understanding of ionizing radiation and radiation exposure, conceptual
models of potential radionuclide releases and exposure pathways, equations and other
quantitative resources, and available mitigation options. Site managers can pair this report with
site-specific information to identify possible exposure pathways, determine whether complete
exposure pathways exist, and which carcass management options are compatible at their site.
Because well-informed carcass management decisions are site-specific, quantitative exposure
estimates presented in this report should not be interpreted as actual exposures associated with
the management options.
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Table ES. 1. Qualitative Ranking of Livestock Carcass Management Options -
Containment vs. Treatment Options
Management Type*
Management
Option
Summary of Potential Exposures
Rank 1:
Containment
Options
Containment options
Off-site
Landfilling
¦ Managing carcasses at an off-site facility authorized to accept
radioactive waste would contain the radioactivity and eliminate or
reduce exposures.
¦ Capacity, distance, and cost might limit feasibility.
prevent or reduce the
release and dispersal
of contaminants,
including
radionuclides and
On-site Burial
¦Without proper siting, on-site burial has the potential to contaminate
groundwater with mobile radionuclides, particularly with longer
half-lives.
¦ A thick depth of compacted cover soil will block most radiation at
the surface.
radionuclide-
containing particles.
These options could
reduce the bulk of the
carcasses.
On-site
Composting
W indrow
¦ A properly constructed windrow would produce a minor amount of
leaching, and less potential exposure, compared to burial.
¦ Bulking material absorbs most of the leachate, would block most
beta particles, but provide limited blockage of gamma radiation.
¦ For radionuclides with relatively short half-lives, the windrow can
be left in place until radioactivity declines to acceptable levels.
On-site
Compost
Application
¦ Composting does not destroy radioactivity and most of the
radionuclide contamination will be present in the finished compost.
¦ Ingestion exposure can occur if compost is applied to soil where
crops or livestock are farmed or where soil can erode to surface
water.
Rank 2: Treatment
Options
Treatment is intended
to reduce the volume
of the carcasses and to
Off-site
Incineration
¦ Commercial waste incinerators are not licensed to accept radioactive
waste.
¦ If incineration is allowed, air pollution control equipment would
provide more protection than uncontrolled combustion options.
¦ Combustion ash would contain concentrated radionuclides.
reduce their noxious,
infectious, or toxic
properties.
Radioactivity is not
destroyed by
Off-site
Rendering
¦ Although air and water releases are regulated, rendering facilities
are not designed or permitted to process radioactive livestock,
making this option unlikely.
¦Radionuclides are not destroyed and would remain in rendering
products and wastes,possibly at increased concentrations.
treatment.
On-site Open
Burning and
Air-curtain
Burning
¦ Combustion is not effective in reducing the radioactivity levels in a
waste stream, and contamination would be spread by uncontrolled
air emissions.
¦ Exposure could result from contamination of air, soil, water, and
biota.
¦ Combustion ash would contain concentrated radionuclides.
*Rank 1 are the options least likely to result in exposure.
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Acronyms and Abbreviations
Ac ronym/ Abb re viatio n
Stands For (Country or Agency Affiliation)
ac
acre(s)
APHIS
Animal and Plant Health Inspection Service (USDA)
BD
soil bulk density
Bq
becquerel(s)
Bq"1
perbecquerel(s)
C
coulomb (s)
CERCLA
Comprehensive Environmental Response, Compensation, and Liability Act
(Superfund)
Ci
curie (s)
cm
centimeter(s)
Cs
cesium
134Cs
cesium-134
137Cs
cesium-137
d
day(s)
DAF
dilution attenuation factor(s)
DHS
Department of Homeland Security (U.S.)
DIL
Derived Intervention Levels (U.S. FDA)
dps
disintegrations per second
dw
dry weight
EPACMTP
EPA Composite Model for Leachate Migration with Lransformation Products
(EPACMLP)
esu
electrostatic unit
eV
electron volt(s)
FRPCC
Federal Radiological Preparedness Coordinating Committee (U.S.)
ft
foot (feet)
ft2
square foot (feet)
ft3
cubic foot (feet)
g
gram(s)
Gy
gray(s)
hr
hour(s)
ha
hectares
HHRAP
Human Health Risk Assessment Protocol (USEPA)
I
iodine
1311
iodine-131
IAEA
International Atomic Energy Agency
ICRP
International Commission on Radiological Protection
IND
improvised nuclear device
XI
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Ac ronym/ Abb re viatio n
Stands For (Country or Agency Affiliation)
IUs
international units
J
joule(s)
kBq
kilobecquerel(s)
kg
kilogram(s)
/kg-d
per kilogram per day
/kg-hr
per kilogram per hour
km
kilo met er(s)
km2
square kilometer(s)
L
liter(s)
lb
pound(s) (weight)
LLRW
low level radioactive waste
m
meter(s)
m2
square meter(s)
m3
cubic meter(s)
MCL
maximum contaminant level
MCLG
maximum contaminant level goal
MeV
megaelectron volt(s)
mg
milligram(s)
mrem
millirem(s)
mSv
millisievert(s)
MT
metric ton
No
initial radioactivity
NHSRC
National Homeland Security Research Center (USEPA)
NNSS
Nevada Nuclear Security Site
NPP
nuclear power plant
np
radionuclide is not present
NRF
National Response Framework
ORNL
Oak Ridge National Laboratory
pCi
picocurie(s)
PAG
Protective Action Guides
PPE
personal protective equipment
PRG
Preliminary Remediation Goals for Radionuclides (USEPA)
R
roentgen(s)
Rad
roentgen absorbed dose
RCRA
Resource Conservation and Recovery Act
RDD
radiological dispersion device
Rem
radiation exposure-man
S"1
per second
s
second(s)
XI1
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Ac ronym/ Abb re viatio n
Stands For (Country or Agency Affiliation)
90Sr
strontium-90
Sv
sievert(s)
t
time
(iCi
microcurie(s)
U.S.
United States (adjective)
USD A
United States Department of Agriculture
USDOE
United States Department of Energy
USEPA
United States Environmental Protection Agency
USFDA
United States Food and Drug Administration
USNRC
United States Nuclear Regulatory Commission
vDpt
total radioactivity addition
WHO
World Health Organization
WNA
World Nuclear Association
wvv
wet weight
Yr
year(s)
Zs
soil mixing zone depth
y
gamma radiation
P
beta particle
a
alpha particle
X
first-order decay rate constant (disintegrations per second)
XI11
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1. Introduction
Established by the Department of Homeland Security (DHS), the National Response Framework
(NRF) is a single comprehensive approach to domestic incident management.1 The NRF
provides the context for DHS and other federal departments and agencies to work with each
other and with communities to prevent, prepare for, respond to, and recover from hazards such as
natural disasters, acts of terrorism, and pandemics.
In support of the NRF, the DHS is funding research in collaboration with the United States
Environmental Protection Agency's (USEPA's) National Homeland Security Research Center
(NHSRC) and the United States Department of Agriculture's (USDA's) Animal and Plant Health
Inspection Service (APHIS) to assure the proper management of animal carcasses following
major environmental incidents such as a natural disaster, foreign animal disease outbreak,
chemical or radiological contamination incident, or other large-scale emergencies. Proper
management of livestock carcasses following such emergencies is needed to protect humans,
livestock, wildlife, and the environment, and to enhance food and agricultural security.
1.1. Purpose and Scope
This report focuses on relative
exposures and hazards for different
livestock carcass management
options in the event of a
radiological emergency. Selection
of radionuclides for the assessment
is described in Problem Formulation
in Section 2.
This exposure assessment builds on
this earlier research by using
consistent assumptions about the
carcass management options (e.g.,
pyre construction and fiiels), scale
of mortality, and site conditions
(USEPA 2017a, 2018a, 2018b).
These documents are referenced in this report when previous assumptions, methods, and
conclusions remain relevant to carcass management for the current assessment.
This report focuses on relative exposures and hazards for different livestock carcass management
options in the event of a radiological emergency. Potential scenarios for a radiological
contamination of livestock are similar to potential scenarios for chemical contamination in that
the contamination could result from events that are unintentional (e.g., nuclear facility or other
nuclear accidents, accidental feed contamination) or intentional (e.g., criminal or terroristic acts).
Depending on the nature of the event, the radiological contamination could be lethal or sublethal
to the livestock, and the contamination could be limited mainly to the livestock (e.g., from feed
contamination) or widespread such as from radioactive fallout. This assessment assumes that
1 Information about the National Response Framework is available at https://www.fema.gov/pdf/emergency/nrf/nrf-
core.pdf
Currently 400 nuclear reactors are in operation with 65
new ones under construction and another 165 planned
around the world. Since the atomic bomb exploded at
Alamogordo, New Mexico more than 70 years ago,
more than 2,000 bombs have been tested, injecting
radioactive materials into the atmosphere and over
200 small and large accidents have occurred at
nuclear facilities. In addition, large quantities of
radiological wastes are generating every year that wll
need to be stored for thousands of years to come.
Radioactivity has seriously harmed midlife at
Chernobyl and Fukushima. The probability of future
accidents or nuclear terrorism could have health and
environmental consequences of radioactivity.
l
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contamination does not hinder safe access to the affected livestock or implementation of carcass
management activities.
1.2. Report Organization
Section 2 defines provides background information on radioactivity and radioactive hazards for
the assessment. Section 3 describes how exposures might result from each of the management
options and how exposures are estimated for this assessment. Section 4 presents the results of the
assessment and uncertainties, and Section 5 documents quality assurance, and Section 6
identifies the literature cited. Conceptual models for livestock carcass management options are
provided in Appendix A and additional radionuclide exposure information is provided in
Appendix B.
2. Pro bit lation
Problem formulation for the radiological exposure assessment defines the radiological
emergency scenario, radionuclides of concern, and livestock carcass management options.
Aspects of the project scope and assessment scenario that are not specific to the radiological
emergency or radiation exposure are consistent with the previous exposure assessments for
natural disaster, foreign animal disease outbreak, and chemical emergency scenarios. These
include standardized environmental settings and assumptions for specific livestock carcass
management options (e.g., unit design, time requirements). These assumptions are identified in
Section 3 with discussion of the management-specific approaches.
As in the previous assessments, livestock mortality is assumed to occur at a hypothetical farm.
The farm's location and regional factors do not preclude the availability or feasibility of any
carcass management option. In addition, impacts of the radiological emergency do not preclude
access to the site or on-site carcass management activities. Humans potentially exposed include
adult residents, child residents, and workers participating in carcass management. The farm
includes agricultural fields and a home garden that supplies the farm residents' fruits and
vegetables. The residents also produce their own livestock food products at home, including
beef dairy, pork, poultry, and eggs; fish for consumption are caught in an on-site lake. Farm
residents obtain drinking water from an on-site groundwater well.
2.1. Radiological Incident Scenario
There are many possible scenarios by which radiation and radioactive materials could be
released to the environment accidentally or purposely. Examples discussed in one or more
previous study (e.g., Dennison 2016; USEPA 2013; USDHS and FEMA 2008; USNRC 2016)
include the following:
¦ Accident at nuclear power plant (NPP) or nuclear weapons facility - Nuclear power is
used to generate electricity at 99 plants in 30 states (WNA2017). Accidents at NPP have
released radioactivity into the environment. Perhaps the most well-known accident occurred
at the Three-Mile Island plant in Pennsylvania in 1979. Following a technical failure,
concern over a possible hydrogen explosion prompted operators to vent some gases
containing radioactivity. Other well-known NPP accidents occurred at Chernobyl, Ukraine
in 1986 and Fukushima, Japan in 2011.
¦ Detonation of nuclear bomb - Intentional nuclear detonations include weapons testing and
the use of nuclear bombs on Hiroshima and Nagasaki in 1945. A nuclear blast releases
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massive amounts of energy, which dissipate as a fireball, blast forces/waves, prompt
radiation, light and heat (thermal energy), and delayed ionizing radiation (i.e., fallout:
nuclear fragments created in the fission process that turn into radioactive elements, which
attach to vaporized debris particles from the explosion). A nuclear explosion can produce
more than 300 isotopes by the fission process and other radioactivity induced by neutrons.
1 Release of a radiological dispersion device (RDD)or improvised nuclear device (IND)
as an act of terrorism - An RDD is intended to spread radioactive material with
conventional explosives or by another means (USDHS and FEMA 2008; USEPA 2013). Air
dispersion of radioactive materials would likely be no more than a few blocks or a few miles
(USNRC 2014). An IND is a crude, yield-producing nuclear weapon fabricated from stolen
fissile materials. If an IND does not result in a nuclear explosion, consequences would be
similar to an RDD, but with fissile materials dispersed locally. If a nuclear explosion does
occur the consequences would be similar to those from a nuclear bomb, but likely on a
smaller scale.
¦ Transportation accidents - Transport of small quantities of radioactive materials occurs
daily to supply materials for medical treatments and other applications and to dispose of
materials with longer half-lives after use. Transportation of large quantities of radioactive
materials occurs via highly protected shipments at infrequent intervals. Materials
transported from uranium or thorium mining sites are not sufficiently enriched to pose a risk
of a nuclear explosion. However, transport of final fuel rod assemblies toNPPsismore
dangerous and is carefully guarded. In the future, there also will be transport of spent fuels
from NPP holding ponds to deep storage sites (e.g., in Nevada).
Livestock could be contaminated with radioactive material by any of these events. For the
purposes of comparing livestock carcass management options, it is not necessary to develop a
detailed incident scenario. However, the event type is relevant to selecting radionuclides for the
assessment, the way livestock are contaminated, and degree of contamination.
For carcasses to be radioactive at levels that require culling, they must have absorbed sufficient
quantities of longer-lived radioactive isotopes to become radioactive themselves or be
contaminated externally at high levels with no means of decontaminating their surfaces.
Livestock near the damage zone of an explosion might already be dead or require humane
culling. Based on a semi-quantitative assessment (USEPA 2017a), releases associated with
carcass transportation are assumed to be insignificant and are not included in this assessment.
For a radiological emergency to be of sufficient magnitude and to release radioisotopes with
longer half-lives, a serious NPP accident, detonation of an IND, or detonation of a nuclear bomb
would be needed. Following such an event, livestock can be externally contaminated by fallout
or contact with contaminated soil or other media. Internal contamination can occur via inhalation
to an air-borne radioactive plume, ingestion of fallout-contaminated forage or feed, incidental
ingestion of fallout-contaminated matter, and/or ingestion of contaminated surface or
groundwater. Following the Fukushima incident, wild boar were found to have elevated levels of
137Cs likely from ingesting mushrooms, which are cesium hyperaccumulators (Merz etal. 2015).
In addition, contaminated rice straw and grass used as feed resulted in elevated cesium
radioactivity in beef (Kelecom et al. 2011) and horse meat (Manabe et al. 2016).
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In some cases, measures are available to decontaminate livestock that have ingested
radioisotopes (Dennison 2016; Manabe et al. 2016). For example, providing clean food and
water can help eliminate many isotopes from the body, and binding agents like bentonite clay or
Prussian blue might prevent absorption. If the radioisotope(s) has a short half-life (e.g., 1311) the
passage of time might be all that is required to salvage the livestock. Similarly, milk
contaminated with 1311 can be frozen or powdered and stored until radiation falls to an acceptable
level (Dennison 2016). These options are discussed further in Appendix B. Although
decontamination options should be considered in the event of an actual radiological emergency,
they are not included in the scenario for this assessment of contaminated livestock management.
Considering the information above, the radiological incident scenario for this assessment
includes beef cattle that have ingested feed contaminated by fallout from an NPP accident. The
level of exposure is sublethal to the cattle, but sufficient to raise concerns about human exposure
from beef consumption. Whether or not the beef contamination exceeds food safety standards,
the beef will not enter the market and the animals are euthanized. The feed may have come from
on- or off-site, but any on-site contamination from the accident (e.g., from fallout) is not so
severe as to displace residents or limit the feasibility of managing carcass at the site.
2.2. Radionuclides of Concern
This section identifies the radionuclides included in the assessment and levels of contamination.
Before presenting those aspects of the assessment in Section 2.2.2, Section 2.2.1 provides
background information on types of radiation, and measures of radiation intensity and exposure.
2.2.1. Measures of Radiation Emissions and Exposures
Radiation covers electromagnetic energy of all wavelengths (radio waves though visible light
through X-rays and higher energies). This assessment considers only "ionizing radiation,"
radiation with sufficient energy to knock electrons out of atoms. Ionizing radiation can be pure
energy or energetic particles. There are four major types of ionizing radiation (Dennison 2016;
USNRC 2014):
¦ Gamma (y) and X-rays - pure energy (photons), very short wavelengths; penetrate most
materials and require several centimeters of lead to block. However, being pure energy,
gamma rays cannot be "ingested"; radionuclides that emit gamma rays can be ingested.
¦ Beta(P) particles - single negatively charged electrons (-1); high energy electrons can pass
through about 1.25 centimeters of water or animal tissue, although it can be blocked by a
layer of aluminum foil. Externally received beta radiation can burn skin.
¦ Alpha (a) particles - consist of 2 neutrons and 2 protons, positively charged (+2); are
relatively large and easy to block (e.g., sheet of paper, clothing, skin layer).
¦ Neutrons - fast moving free neutrons (i.e., outside of an atom's nucleus); have no charge
and can penetrate most materials; produced only by nuclear fission or fusion, not by natural
radioactive decay.
Radionuclides have distinct first-order decay rate constants (disintegrations per second), which
are denoted as X ("lambda"). Decay constants are typically reported as half-lives, the time
required for half the radionuclides to decay. Half-lives (/',) are calculated from decay constants
with using Equation 2.1.
4
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tV2 ~
In (2)
0.693
(Eqn. 2.1)
Hundreds of man-made radioactive isotopes have half-lives of a few seconds or less.
Radionuclides of concern have much longer half-lives, days, years, to millions of years or more.
At least four metrics are used to measure radioactivity and exposure, as listed in Table 1.
Although international units differ from units commonly used in the United States, use in the
United States is evolving toward the international units (IUs). Thus, all results reported in this
assessment conform to International Units (IUs). Further information is provided in Appendix B.
Table 1. Measures of Radioactivity and Exposure
Measure
International
United States
Equivalency
Equivalency
Units
Units
Disintegrations
1 Becquerel (Bq)
1 Curie (Ci) =
1 Ci =
1 Bq =
per second (dps)
= 1 dps
decay of 1 g of
3.7 E+10 Bq
0.000027 (iCi
radium /s
Dose equivalent
Sievert (Sv)
rem (radiation
1 rem=
1 Sv =
(net effect)
exposure-man)
0.01 Sv
100 rem
Gamma and X-ray
Coulomb/kg
Roentgen (R)
1 R =
1 C/kg =
energy emission
(C/kg)
2.58 E-04 C/kg
3880 R
rates
Coulomb/
R/hr - measured
1 R/hr =
1 C/kg-hr =
kg-hour
by radiation
2.58 E-04 C/kg-hr
3880 R/hr
(C/kg-h)
detection
equipment
Amount of energy
Gray (Gy)
Roentgen
1 Rad =
1 Gy =
absorbed in body
absorbed dose
0.01 Gy
100 Rad
(gamma rays)
(Rad)
Note: One electron volt (eV) is a unit of energy equal to approximately 1.6E-19 Coulombs (C) or Joules (J).
Abbreviations: Bq = Becquerel(s); C = Coulomb(s); Ci = Curie(s); dps = disintegrations per second; eV= electron
volt(s); s = second; Sv = sievert(s); h = hour; g = gram; Gy = gray(s); kg = kilogram; R = roentgen(s); Rad =
roentgen absorbed dose; rem = radiation exposure-man; (iCi = microcurie(s).
2.2.2. Selected Radionuclides of Concern
Radionuclides of concern for the assessment are identified based on releases from NPP
accidents. Table 2 lists the three most memorable NPP accidents that released radiation to the
environment. In the Chernobyl and Fukushima incidents, radioactive materials in air traveled
over more than half the globe, depositing in many countries. Releases from Fukushima also have
contaminated groundwater in Japan and the Pacific Ocean with radioactive materials.
5
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Table 2. Accidents at Nuclear Power Plant—Past Examples
Reactor
Date;
Location
Area
Contaminated by
Documented
Materials
Estimates of
Quantities
Reference
Release
Released
Released
Three-Mile
March 28,
2 million people
85Kr
Total release =
FRPCC
Island
1979;
within 50 miles;
133Xe
1.0E+15 Bq;
2007
outside
however, no
131I
1311 release =
Harrisburg,
significant ground
5.6E+11 Bq
Pennsylvania
contamination
Chernobyl
April 26,
29,400 km2
133Xe
4% of core
FRPCC
1986;
contaminated to
131I
released
2007;
Ukraine
180 kBq/m2;
current exclusion
zone =4,300 km2
132Te (to 132I)
134Cs
137Cs
total release =
8 E+18 Bq;
1311 release =
1.8 E+18 Bq
(50% of 131I in
reactor);
137Cs defines
current exclusion
zone of 37 km
WNA 2016
Fukushima
March 11,
Releases to the air
134Cs
Volume of
USEPA
Daiichi
2011; Japan
and ocean; area of
137Cs
contaminated soil
2013;
Reactors
3,000 km2
131I
in Japan estimated
WNA
contaminated
238Po, 239Po,
to exceed 1 billion
2016;
above 180 kBq/m2
240Po,241Po,
132Te
90 Sr
cubic feet
(28,300,000 m3)
Merz etal.,
2015
Abbreviations: km = kilometer(s); km2 = square kilometer(s); kBq= kilobecquerel(s); m2 = square meter(s); m3 =
cubic meter(s); FRPCC = Federal Radiological Preparedness Coordinating Committee (U.S.); WNA = World
Nuclear Association. Full references are at the end of the report.
Based on the past incidents, and a goal of including radionuclides spanning a range of half-lives,
the four radioisotopes selected for the exposure assessment are listed in Table 3. Although many
other isotopes might be released initially, most have very short half-lives (e.g., minutes to
seconds or less), and materials remaining hours later are those listed above. Radioactive gases
such as xenon and krypton can be released in large quantities but remain in gas phase where they
are dispersed and diluted in air. Other long-lived radioisotopes are less likely to be released to
the environment (e.g., 235U, 238Pu).
6
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Table 3. Radionuclides Included in the Exposure Assessment
Radionuclide
Radiation Types
Half-life a
Half-life Seconds
De cay cons tant (s 1)
134Cs
|3, y emitter
2.0648 Years
6.5E+07
1.1E-08
137Cs
|3, y emitter
30.1671 Years
9.5E+08
7.3E-10
90 Sr
(3 emitter
28.79 Years
9.1E+08
7.6E-10
131J
(3, y emitter
8.0207 Days
6.9E+05
1.0E-06
a Source: Pravalie 2014.
Abbreviations: p = beta particle; y = gamma radiation; s_1 = per second.
In the Fukushima incident, in which beef cattle ingested contaminated feed, the primary
radionuclides of concern in beef were 134Csand 137Cs. 131Iwas not a predominant in beef but was
of concern in milk and tap water (Merz et al. 2015).
2.3. Livestock Carcass Management Options
The previous exposure assessments for livestock carcass management in the event of a natural
disaster, foreign animal disease outbreak, and chemical emergency all considered the seven well-
established options listed in Table 4. These include three options conducted oft-site at existing
commercial facilities, and four options that would be conducted on site. Appendix A provides
conceptual models for each of the management options and related activities.
Table 4. Livestock Carcass Management Options Considered for the Exposure Assessment
Management Type
Specific Management Option
Combustion-based Management
¦ On-site Open Burning (Pyre)
¦ On-site Air-Curtain Burning
¦ Off-site Fixed-facility Incineration
Land-based Management
¦ On-site Unlined Burial
¦ On-site Composting
¦ Off-site Lined Landfill
Materials Processing
¦ Off-site Rendering
Combustion-based waste management can be effective in reducing the toxicity of chemical
contaminants, the infectivity of microbial contaminants, and the bulk of the waste. The air
emissions and ash residue must be considered when evaluating the effectiveness of this type of
waste management, but, if applied appropriately, combustion could reduce the hazard associated
with certain waste streams. Therefore, in the previous exposure assessments in this series, for
natural disaster (USEPA 2017a), foreign animal disease outbreak, (USEPA 2018a) and chemical
emergency (USEPA 2018b) scenarios, combustion-based management options were My
assessed.
However, while combustion-based management would reduce the bulk of radioactive carcasses,
combustion is not effective in reducing the radioactivity levels in a waste stream. "The
combustion process does not destroy... radioactivity nor does it change the rate of radioactive
decay, but rather it changes only the chemical and physical forms of the radionuclides. The most
often encountered radionuclides, tritium, carbon, and iodine, are generally released with little or
no retention in the incinerator" (USEPA 1991). Therefore, for the scenarios under consideration
7
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in this assessment, combustion-based management, which would disperse radioactive
contaminants, was deemed less effective than land-based management, which could contain such
contaminants.
The NRC limits carcass "treatment or disposal by incineration" to the following conditions: "A
licensee may dispose of the following licensed material as if it were not radioactive" if the
concentration in the material is "0.05 microcurie (1.85 kBq), or less, of hydrogen-3 or carbon-14
per gram of animal tissue, averaged over the weight of the entire animal" (10CFR § 20.2004-§
20.2005). So, where levels of radioisotopes are extremely low, where they can be purged from
living animals, or where they can decay in a short period of time, culling those animals could
become unnecessary. If culling occurred, such carcasses could be treated as non-radioactive
waste.
Open pyre or air-curtain burning were not ranked among the top management strategies
for the scenarios considered in this assessment for several reasons. First, as noted above,
NRC regulations strictly limit the treatment and disposal of radioactive waste by incineration.
Also, open pyre and air-curtain burning do not reduce radioactivity or the associated hazard
associated with radioactive carcasses. In addition, these combustion technologies will release
radioisotopes to the air; the remaining radioisotopes would become concentrated in the bottom
ash, which could necessity its (costly) management as a radioactive waste. Finally, open pyre or
air-curtain combustion disperses rather than contains the hazard.
Similarly, incineration within a device such as an incinerator or industrial furnace was not
ranked among the top management strategies for the scenarios considered in this
assessment. The reasons are the same: NRC regulatory barriers, lack of hazard reduction,
creation of radioactive ash disposal burden, and dispersal of radioactive contaminants. In
addition, procedures and protocols for worker protection from radiation would be required, and
the facility could need to be decontaminated after.
Mixed-waste incinerators are specially permitted by NRC to manage radioactive waste, but
these are not ranked among the top waste management strategies for the scenarios
considered here either. Incineration of hazardous waste mixed with radioactive waste ("mixed
waste") is permitted but "these incinerators are, by their nature, expensive and difficult to design
and operate" (Diederich and Atkins 2008). Also, mixed-waste incineration has fallen into
disfavor; "Combinations of technical, regulatory, economic and political factors have constrained
the overall use of [mixed waste] incineration. In both the Government and Private sectors, the
trend is to have a limited number of larger incineration facilities that treat wastes from multiple
sites. Each of these sector [sic] is now served by only one or two incinerators" (Diederich and
Akins 2008). So, mixed-waste capacity is limited, is generally dedicated to sector-specific
purposes (hospital waste, research facility waste, DOE waste), and is expensive. Mixed-waste
incineration is not an available or a practical alternative in the event of a large-scale agricultural
incident.
¦ Rendering is also not a practical or practicable option. Radioisotopes would remain in
all products of the rendering process; none would be useful; products and contaminated
waste waters would have to be treated as radioactive waste, which negates that value of
rendering. NRC regulations do not permit animal tissue in which radioactive materials have
8
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been introduced to be disposed of in a manner that would permit its use as human food or as
animal feed (10CFR § 20.2005), which would preclude rendering.
Thus, only three of the original seven carcass management options remain for lull analysis in this
assessment:
¦ On-site burial. After radiation levels have declined to levels that could be tolerated by
appropriately protected workers on-site for limited durations, livestock could be buried on-
site if sufficiently large areas away from water wells were suitable (e.g., sufficiently deep
trenches could be dug with the bottom more than one meter above the high-water table). The
best burial sites would be in areas with very deep aquifers and in areas designated as human
exclusion zones due to ground-level contamination over large areas.
¦ On-site composting. After radiation levels have declined to levels that could be tolerated by
appropriately protected workers on-site for limited durations, livestock could be composted
on-site. Appropriate precautions to prevent runoff and infiltration would be required.
Compost containing radionuclides with short half-lives might become suitable for
application to an agricultural area in time. If the radionuclides have long half-lives, the
windrow would require long-term monitoring of temperature and integrity (e.g., from
damage by wildlife), or the finished compost could be landfilled or otherwise managed off-
site. Composting the carcasses would reduce pathogens and reduce both the moisture and
volume of the carcasses, which is beneficial if the compost is landfilled.
* Off-site Landfills. Landfilling would require transport to one of four commercially licensed
low-level radioactive waste (LLRW) disposal facilities, which are licensed by states through
agreements with the U.S. Nuclear Regulatory Commission (USNRC) under the Atomic
Energy Act of 1954. Brandl et al. (2012) cites estimates of $8,000 per cow for disposal at
LLRW facilities. The extent to which this option is even feasible depends on the number of
livestock culled compared with available LLRW capacity.
High-level radioactive waste is managed primarily by the U.S. Department of Energy (USDOE)
at its Nevada Nuclear Security Site (NNSS), which is on what was previously the Nevada
nuclear bomb test site. USDOE is developing that facility, however, for long-term storage of
spent nuclear fuels that will remain radioactive for thousands, millions, or billions of years. Thus,
that facility will be used only for high-level radioactive waste from nuclear programs and
reactors.
The possible limitations to off-site management in radiological disposal facilities, particularly
after disposal of contaminated materials such as human clothing, worker protective clothing,
contaminated soils, and other contaminated materials, means that other, ad hoc waste
management options might be required. Options requiring building of new LLRW facilities (e.g.,
on the contaminated land, in Department of Defense lands, or Department of the Interior lands)
or modifications to existing Resource Conservation and Recovery Act (RCRA) facilities would
not be available soon enough to handle cattle culled in the intermediate phase of responses.
These issues emphasize the importance of salvaging livestock when possible even if they are
cannot provide usable products (e.g., milk that is safe to drink, meat with radioactivity levels
below the United States Food and Drug Administration (USFDA) Derived Intervention Levels
[DILs]) for many months after an incident.
9
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Based on the above, exposures are quantified for the on-site burial and composting options. For
burial, the trench could be constructed to include a low-permeability liner, thereby minimizing
the drinking water exposure pathway. The scenario for this assessment does not include a liner.
In a radiological emergency, regulators might not require a liner if the carcasses must be
managed promptly or for other reasons of technical impracticability. All assumptions about the
burial trench (e.g. size, cover fill, placement relative to the on-site well), including the exclusion
of a liner, are consistent with the exposure assessments for a chemical emergency, foreign animal
disease outbreak, and natural disaster.
Composting is assumed to occur on-site in windrows constructed outdoors and on bare earth.
Design specifications and performance, including materials, dimensions, and placement relative
to the on-site well are consistent with the earlier assessment scenarios. As abase case,
composting is complete in eight months (based on Looper 2001), at which time the finished
compost is tilled into soil on-site at an agronomic rate. The composting duration is varied in the
assessment to evaluate its effect on estimated radiological exposures.
To study potential exposures, finished compost in this assessment is applied to soil on site
containing varying quantities of the selected radionuclides. The amount of compost, the
application rate, and tillage depth are the same as the three previous exposure assessments.
Potential exposure pathways beginning with compost application include ingestion of home-
grown foods produced at the compost application site and incidental soil ingestion.
3. Exposure Estimation
This section describes the data, assumptions, and methods used to assess radiological exposure
following on-site carcass management in the event of a radiological emergency. Section 3.1
identifies the initial levels of radiation in the carcasses. Section 3.2 discusses estimation or
radioactive material releases from the carcasses into potential exposure pathways. Section 3.3
discusses the fate and transport methods and the resulting levels of radioactivity in drinking
water and soil, and Section 3.4 presents the methods used to characterize exposure doses to
exposed individuals. There is an inherent challenge at considering multiple exposure pathways in
this estimation due to wide-ranging exposure timelines in various media under different fate and
transport scenarios. For some exposure routes such as from food consumption, advisory levels
based on emergencies from shorter term exposures are used; for other exposure routes such as
groundwater or drinking water, longer-term advisory levels were used, since for some exposure
pathways, exposure continues long past the emergency phase.
3.1. Initial Carcass Contamination
The radiological exposure assessment begins with "base case" assumptions about the level of
livestock contamination. The base case radiation level for each radionuclide is accompanied by a
range of conceivable alternative levels that are also assessed for comparison. The range of
radiation levels for this assessment are based on radiation levels observed in Japan following the
Fukushima nuclear accident.
While chemical exposure assessments involve mass-based contaminant concentrations,
radiological exposure assessments use one or more measures of radiological exposure and
activity (see Table 1). For this assessment, levels of contamination are expressed in radionuclide
activity concentrations, specifically Becquerels (Bq) per unit of contaminated substance (e.g.,
10
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Bq/kg of soil, Bq/L of drinking water). A Becquerel is equal to 1 radioactive disintegration per
second.
Radiation monitoring in foods from the Fukushima and neighboring prefectures initially focused
on vegetables, which peaked shortly after the accident on March 11, 2011 (Merz etal. 2015). By
August, radiation levels in vegetable were mostly below regulatory limits, with the exception of
mushrooms that accumulate radiocesium (i.e., 134Csplus 137Cs). Radiation in meat and dairy
gradually rose following the accident, with cesium radionuclide activity concentration in beef
first exceeding the provisional regulatory limit of 500 Bq/kg in early June. The highest level
reported, 4,350 Bq/kg in mid-July, was in beef from Fukushima Prefecture. Exceedances were
found in beef from other prefectures, possibly due to contaminated rice straw used as feed
(Kelecom et al. 2013). The highest levels above the provisional standard by prefecture are
presented in Table 5. In addition to beef, cesium radiation was detected in meat from wild boar,
deer, and horse (Merz et al. 2015; Manabe et al. 2016). In boar, the highest detections were
14,600 and 13,300 Bq/kg and in deer meat, 1,069 Bq/kg. Japan lowered the radiation standard
applicable to meat from 500 to 100 Bq/kg on April 1, 2012. At this level, at least one sample of
horse meat, at 100Bq/kg exceeded the standard (Manabe etal. 2016).
Table 5. Highest Radiocesium Detections by Prefecture
Prefecture
Highe st Detection in B eef
(Bq/kg)
Fukushima
4,350
Iwate
2,430
Tochigi
2,200
Miyagi
1,400
Akita
781
Yamagata
590
Source: Kelecom et al. (2013) (Full reference is at the end of the report.) Beef
contamination byCs-134 and Cs-137 in Japan, from the Fukushima Dai-ichi
NPP accident. INAC 2013: International Nuclear Atlantic Conference, Brazil.
Based on the range of radiocesium levels detected in beef, as well as the domestic and
international standards food and drinking water radiation standards, the base case level of 134Cs
and 137Cs contamination in cattle carcasses is 500 Bq/kg. Other levels evaluated in the
assessment are 50, 5000, and 50000 Bq/kg as shown in Table 6. Beef samples can be considered
representative of whole carcass concentrations because cesium is rapidly distributed throughout
the body following exposure (ATSDR 2004a).
Table 6. Initial Radionuclide Activity Levels in Livestock Carcass3
Carcass Radionuclide Activity Levels (Bq/kg)
134Cs
137Cs
90 Sr
131 j
50
50
5
100
500
500
50
500
5,000
5,000
500
1,000
50,000
50,000
5,000
5,000
a "Base case" levels are shown in bold text.
11
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Food monitoring following the Fukushima accident generally did not measure levels of90Sr
radiation directly. Radionuclides, including 134Cs and 137Cs which are y and P emitters, are easily
detected with y spectrometry. As a P-emitter only, 90 Sr detection is more laborious (Merz et al.
2015). Based on research associated with the Chernobyl accident and nuclear weapon
explosions, the Japanese government assumed that 137Cs and 90Sr occurs in a constant 10:1 ratio.
Although Merz et al. (2015) report that this ratio is not necessarily constant over time or in
different foods, the ratio is used in this assessment to set the 90 Sr carcass radiation levels (Table
6). Specifically, the base case level is 50 Bq/kg (i.e., 10% of the 137Csbase case level), and other
levels included in the assessment are 10, 100, and 1000 Bq/kg. These assumed levels might
overestimate 90 Sr levels in leachate because it partitions to skeletal tissue (ICRP 1993 as cited in
ATSDR 2004b).
1311 was detected in raw milk, vegetables, and potable water following the Fukushima accident. It
was not found at high levels in beef (Merz et al. 2105), which is consistent with iodine
partitioning being largely confined to extracellular fluid (Brown-Grant 1961 as cited in ATSDR
2004c). Levels of1311 declined rapidly due to its 8-day half-life. Initially, however, levels
exceeded ranged from 932 to 1510 Bq/kg, with a mean of 1210 Bq/kg (Kelecom 2013). For
water, provisional advisory index values for 1311 were established to be 300 Bq/L for adults and
100 Bq/L for infants (WHO, 2018). Because of the partitioning behavior, the reported
concentrations in raw milk, are likely to over-represent the overall concentration in cattle.
3.2. Releases to Environmental Media
The amount of contamination released from carcasses into environmental media is one the
largest uncertainties in the exposure assessments of livestock management options. Release
estimates for this assessment are based on the same information used to estimate chemical
releases for the natural disaster and chemical emergency scenarios.
3.2.1. Burial
For the burial management option, radiological releases from the buried carcasses are contained
in the liquid released from the carcasses as they decompose. Young etal. (2001) estimated that
approximately 33% of the carcass mass is released as fluids during the first 2 months after burial,
with half of that amount released in the first week. If the leachate has the density of water (i.e., 1
kg/L), the amount of liquid released from a single 453.6 kg (1,000 pounds [lb]) cattle carcass in
the first two months is approximately 150 L. With increasing numbers of carcasses, the amount
of leachate is larger. The radionuclide activity concentration of the leachate remains constant
because the area of the trench increases proportionally with the number of carcasses. Table 7
shows the design assumptions for the burial trench with the base case (i.e., 100 carcasses) and
larger numbers of carcasses.
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Table 7. Assumptions for the Burial Management Option
Number of
Carcasses
Burial Trench Design
100
(base case)
¦ 100 cattle carcasses are placed in a single trench that is 9 ft deep, 7 ft wide, and
300 ft long (2.7 by 2.1 by 91.4 m) based on guidelines provided by USDA (2005;
2017).
¦ The carcasses are covered with 6 ft (1.8 m) of soil, including 3 ft (0.9 m) mounded
over the site starting at ground level (USDA 2005; 2017).
¦ An unsaturated zone of 1 m (3.3 ft) extends below the bottom of the burial trench.
500
¦ Carcasses are placed in a single trench that is 5 times as long (457 m) as the base
case.
¦ All other design assumptions are equivalent to the base case.
1,000
¦ Carcasses are placed in a single trench that is 10 times as long (914 m) as the base
case.
¦ All other design assumptions are equivalent to the base case.
10,000
¦ Carcasses are placed in 10 parallel trenches that are equivalent to the trench for
1,000 carcasses.
Abbreviations: ft = foot (feet); m = meter(s); USDA= United States Department of Agriculture.
Complete references are at the end of the report.
The radionuclide activity concentration of the leachate is estimated by assuming that the starting
carcass radioactivity levels (Table 6) are distributed uniformly in all compartments of the
carcass. With this assumption, the concentration of radioactivity in leachate equals the
concentration in the muscle tissue. Assuming the leachate has the density of water (i.e., 1 kgL),
the base case 134Cs radioactivity concentration is 500 Bq/L. Considering the internal partitioning
behavior of the radionuclides discussed above (including considerations of the chemical form of
radionuclides), this assumption is likely to overestimate the leachate radioactivity for 90Sr,
underestimate the leachate radioactivity for 131I, and is not biased in either direction for 134Csand
137Cs.
During the first few months of fluid release from the carcasses, water entering the pit from
precipitation will dilute the liquid. When the fluid release declines after the first few months of
degradation, however, leachate concentrations can depend on local precipitation as well as
conditions in the burial trench. The contribution of precipitation is not included in the leachate
modeling approach for the on-site burial option because depending on when precipitation
occurred, it might or might not dilute concentrations during the most active period of leachate
releases.
The leachate concentrations need to account for radioactive decay over the 2 months during
which the leachate is released. The exponential decay equation, Equation 3.1, can be used to
estimate the radioactivity remaining at a specified time.
N(t) = N0 * (Eqn. 3.1)
Where:
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N(t) = The radioactivity remaining at time (t), e.g., Bq/L
No = The initial radioactivity, e.g., Bq/L
X = The decay constant (disintegrations/sec) of the radionuclide
t = Time (sec)
To estimate the average leachate radioactivity during the release, the total disintegrations per L
over the first two months are divided by time. The total disintegrations can be represented as in
Equation 3.2, where Equation 3.1 is summed from t = 0 to t = F, the number of seconds in two
months:
Co No ^e-^dt (Eqn. 3.2)
In Equation 3.3, the function is integrated. JV0 is constant and thus gets pulled out of the integral.
JV0 * e_A*tdt = JVq * (— ~) * e~XH (from t = 0 to t = F) (Eqn. 3.3)
Finally, to find the total disintegrations, the integrated equation is evaluated across maximum
and minimum bounds by subtracting the evaluation with the lower bound from the evaluation
with the higher bound:
JV0 * (-0 * e~x*^ - JV0 * (-£) * (Eqn. 3.4)
The average leachate radioactivity concentrations from this approach are presented in Table 8.
Considering the uncertainty in the estimated starting radioactivity levels, averaging the initial
and final levels is a reasonable alternative to the approach describe above.
Table 8. Estimated Radionuclide Activity in Leachate from Burial3
Leachate Radionuclide Activity Levels (Bq/L)
134Cs
137Cs
90 Sr
131 j
48.6
48.6
5.0
19.2
486
486
49.9
95.9
4,864
4,864
4,99.0
191
48,645
48,645
4,990.1
959
a "Base case" levels of radioactive contamination are shown in bold text. Non-bold values are conceivable alternative levels that
are assessedfor comparison with the base case. The ranges of alternative levels are based on radiation levels observed in Japan
following theFukushima nuclear accident.
3.2.2. Composting
Releases to the environment from composting include leaching from the windrow and
application of finished compost to soil.
Leaching from the Compost Windrow
Consistent with the previous assessment scenarios, compost windrows are constructed according
to specifications provided by USDA (2005; 2017). Carcasses are placed on abase layer and
covered with a 2 foot (ft) (0.6 m) thick layer of bulking material (e.g., woodchips) on the top and
14
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all sides. For large animals, Glanville etal. (2006) recommends placing one U.S. ton (907 kg) of
carcass, in a single layer, per 8 ft (2.4 m) of windrow. Using this recommendation, the total
length of windrow for 45, 359 kg (50 U.S. tons) of large animal carcasses is 122 m (400 ft). For
the base case, 100 carcasses are placed in two 16 ft (4.9 m) wide by 60 m (200 ft) long
windrows. The windrow is assumed to be placed on bare earth in a well-drained area that is at
least 1 m (~3 ft) above the high-water table level. Table 9 provides the windrow design
assumptions for the base case and larger numbers of carcasses.
For the base case scenario, the compost windrow contains the same number of carcasses as the
burial trench and the amount and rate of liquid released is the same. Therefore, the radionuclide
activity concentrations are the same as for burial (Table 8). However, the bulking material
surrounding the carcasses absorbs most of the liquid. Glanville et al. (2006) and Donaldson et al.
(2012) both reported volumes ofleachate from experimental compost windrows to not exceed
5% of the precipitation that falls on the windrows. Based on that information, the assessment
assumes that only 5% of the volume of fluids released by decomposition will seep into the
ground beneath the windrow. Contaminants in the remaining 95% of the leachate remain in the
windrow. These assumptions have been included in each of the previous exposure assessments.
Table 9. Assumptions for the Composting Management Option
Number of
Carcasses
Compos t Windrow De s ign
100
(base case)
¦ Composting is performed on bare earth (USDA 2005, 2015) in 2 parallel
windrows that are 4.9 m (16 ft) wide by 61 m (200 ft) long.
¦ An initial layer of bulking material (e.g., woodchips) 2 ft deep are placed across
the entire base of the eventual windrow (USDA 2005).
¦ An additional 2 feet of bulking material are placed on the sides and top of the
windrow (USDA 2005).
¦ Runoff from the windrows will be contained with hay bales.
500
¦ Carcasses are placed in 2 parallel windrows that 305 m long, 5 times the length of
the 100-carcass windrows.
¦ All other design assumptions are equivalent to the base case.
1,000
¦ Carcasses are placed in 4 parallel windrows that 305 m long, 5 times the length of
the 100-carcass windrows.
¦ All other design assumptions are equivalent to the base case.
10,000
¦ Carcasses are placed in 20 parallel windrows that 610 m long, 10 times the length
of the 100-carcass windrows.
¦ All other design assumptions are equivalent to the base case.
Full references are at the end of the report.
Application of Finished Compost
According toLooper (2001), composting of dairy cow carcasses generally takes six to eight
months, with 90% of the flesh decomposed after eight weeks. For this assessment, composting is
completed in 8 months and the finished compost is applied to an on-site agricultural field in
accordance with a nutrient management plan. Transport of chemicals from the compost
15
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application site can occur by runoff/erosion to the lake. The effect of composting duration on
exposure is examined in the assessment.
To calculate the radionuclide activity concentration in the finished compost, the initial
radioactivity levels (Table 6) in Bq/kg are multiplied by the weight per carcass (453.6 kg) and
the number of carcasses in the windrow(s). From the radionuclide activity concentration in the
finished compost is subtracted the 5% lost as leachate from the windrow. Radioactive decay
during the 8-month composting period is accounted for using Equation 3.1 and the radionuclide
decay constants in Table 3. The resulting activity levels are then divided by the total weight of
the finished compost. Assuming finished livestock compost has a density of 600 kg/m3 wet
weight (NABCC 2004) and 40% moisture (Chen et al. 2012), the total weight of the finished
compost of 100 cattle carcasses is 161 metric tons wet weight or 96.4 metric tons dry weight.
Table 10 presents the estimated radionuclide activity concentrations in finished compost for four
starting levels of contamination.
Table 10. Estimated Radionuclide Activity in Finished Compost3 for Four Contamination
Levels
Radionuclide Activity Levels in Finished Compost (Bq/kg dw)
134Cs
137Cs
90 Sr
131 j
1.9E+01
2.3E+01
2.3E+00
3.5E-08
1.9E+02
2.3E+02
2.3E+01
1.7E-07
1.9E+03
2.3E+03
2.3E+02
3.5E-07
1.9E+04
2.3E+04
2.3E+03
1.7E-06
a "Base case" levels of radioactive contamination are shown in bold test.
Abbreviations: dw = dry weight.
3.3. Fate and Exposure Modeling
Fate and transport modeling for the carcass burial option begins with the radionuclide activity
concentrations in leachate estimated in Section 3.2.2 and end with concentrations in well water
used by residents of the site. The same methods are used to model well water contamination
from the compost windrow. Fate and transport modeling for the composting option also includes
calculation of surface soil concentrations at the compost application site.
3.3.1. Leaching from Burial Trenches and Composting Windrows
After seeping into the ground beneath the burial trench or composting windrow, leachate first
passes downward through unsaturated soil until it reaches the water table where it is carried with
the direction of the ambient groundwater flow. The leachate is diluted as it moves through these
two subsurface zones, and the leached radionuclides may be affected by physical and chemical
process that tend to further reduce concentrations with distance from the source (USEPA 1996).
The combined effect of these processes is complex and dependent on site-specific soil and
hydrodynamic properties.
Concentrations of radionuclide activity in well water are estimated by multiplying the initial
concentration in leachate (i.e., Table 8) by dilution attenuation factors (DAFs) from USEPA
(1996). ADAF is a ratio of a source leachate concentration to a concentration in water at a
downgradient well. USEPA developed the DAFs used in this assessment to support regulatory
16
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analysis, such as soil screening level guidance forEPA's Superfund program (USEPA 1996).
Modeling to develop the DAFs used the EPA Composite Model for Leachate Migration with
Transformation Products (EPACMTP), which simulates physical, chemical, and biological
processes in both the unsaturated and saturated zones. The unsaturated and saturated zone
modules of the EPACMTP have undergone extensive verification by USEPA and have been
reviewed by the USEPA Science Advisory Board, which found the model to be suitable for
generic applications such as the derivation of nationwide DAFs (USEPA 1996).
In support of the soil screening level guidance, USEPA used EPACMTP and nationwide site
data (e.g., soil properties at contaminated sites, well location and depth) in a series of Monte
Carlo simulations for six well-placement scenarios. Distances from the source to the well in
these scenarios were 100 m, 25 m, or 0 m from the source, or randomly selected from a
distribution of nationwide data. The well's horizontal offset distance from the plume center line
was randomly selected, either within the plume's width or half the width. Well depths were
randomly selected from nationwide data for most scenarios.
The Monte Carlo analysis USEPA preformed to develop the DAFs varied parameters (e.g., depth
to water table, aquifer thickness, well distance) that are independent on chemical-specific
properties. The analysis assumed a non-degrading, non-sorbing contaminant. This aspect of the
approach causes well-water concentrations to be overestimated, in general. As elements,
radionuclides are affected by only one degradation process, radioactive decay, which is included
for groundwater pathways in this exposure assessment.
Because USEPA determined that the DAF estimates are sensitive to the size of the contaminated
area, it developed DAFs for sources ranging in size from 1,000 to 5,000,000 ft2 (93 to 464,515
m2) and presented charts of the relationships between source size and DAF for various scenarios.
For this assessment, the information presented by USEPA was used to identify DAFs for burial
trenches and composting windrows with 100, 500, 1,000, and 10,000 carcasses. Each of the
DAFs were based on the USEPA scenario in which the well is located 100 m downgradient from
the source.
Table 11 presents the base case radionuclide activity concentrations in water drawn from a well
located 100 m downgradient of a 100-carcass burial trench. The well water concentrations
account for radioactive decay, which is discussed further below. Table 12 shows the DAFs for
burial trenches with increasing numbers of carcasses and their effect on estimated 134Cs
radioactivity in well water.
As in the chemical emergency exposure assessment, this assessment uses DAFs for a
groundwater well 100 m downgradient from a burial trench or compost windrow. The DAF
values are included in Table 12. With each order-of-magnitude increase in the number of
carcasses, the estimated well water concentration increases nearly an order-of-magnitude.
17
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Table 11. Base Case Radionuclide Activity Concentrations in Well Water with Burial of
100 Carcasses
Radionuclide
Radionuclide
Activity in
Carcass (Bq/kg)
Radionuclide
Activity in
Le achate (Bq/L)
DAF
Radionuclide
Activity in in
Well Water3
(Bq/L)
134Cs
500
486
878
0.51
137Cs
500
499
878
0.57
90 Sr
50
49.9
878
0.06
131J
500
95.9
878
4.6E-05
a Estimates include radioactive decay over 90 days of travel from the source to the well.
Abbreviations: L = liter(s); DAF = dilution attenuation factor(s).
Table 12.134Cs Radionuclide Activity Concentrations in Well Water with Burial of
Increasing Numbers of Carcasses3
Number of
Carcasses
Radionuclide
Activity in
Carcass (Bq/kg)
Radionuclide
Activity in
Le achate (Bq/L)
DAF
Radionuclide
Activity in in
Well Water3
(Bq/L)
100
500
486
878
0.51
500
500
486
200
2.2
1,000
500
486
106
4.2
10,000
500
486
13
35.0
a "Base case" levels of radioactive contamination are shown in bold test.
Abbreviations: DAF = dilution attenuation factor(s).
The assessment assumes that 90 days elapse between leaching from the trench until well water is
used. During this time, the radionuclide activity concentrations decline according to their specific
half-lives. The radionuclide activity concentrations remaining after decay are calculated with
Equation 3.1. Table 13 shows reductions due to decay with travel-time assumptions ranging from
0 to 365 days. Comparing the percentage reductions in radioactivity with increasing time shows
that the least change occurs when the radionuclides have either short (e.g., 8 day) or long (e.g.,
30 year) half-lives. The amount of change is greatest for 134Cs, which has an intermediate half-
life of 2.1 years. Thus, the uncertainty associated with the travel time assumption is largest for
radionuclides with intermediate half-lives.
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Table 13. Radionuclide Activity Concentrations in Well Water with Increasing Time
Between Leaching and Water Use, Base Case Burial Option3
Radionuclide Activity in in Well Water1 (Bq/L) (percentage reduction)
Number of Days
134Cs
Half-life 2.1 yr
137Cs
Half-life 30.2 yr
90 Sr
Half-life 28.8 yr
131 j
Half-life 8.0 d
0
5.5E-01 (0%)
5.7E-01 (0%)
5.7E-02 (0%)
1.1E-01 (0%)
60
5.2E-01 (5%)
5.7E-01 (0%)
5.7E-02 (0%)
6.1E-04 (>99%)
90
5.1E-01 (8%)
5.7E-01 (1%)
5.6E-02 (1%)
4.6E-05 (>99%)
120
5.0E-01 (10%)
5.6E-01 (1%)
5.6E-02 (1%)
3.4E-06 (>99%)
180
4.7E-01 (15%)
5.6E-01 (1%)
5.6E-02 (1%)
1.9E-08 (>99%)
240
4.4E-01 (20%)
5.6E-01 (1%)
5.6E-02 (2%)
1.1E-10 (>99%)
360
4.0E-01 (28%)
5.6E-01 (2%)
5.5E-02 (2%)
3.4E-15 (>99%)
a "Base case" levels of radioactive contamination are shown in bold test (i.e., 90 days).
Abbreviations: d = day(s); yr = year(s).
Radioactivity in well water downgradient from the compost windrow is calculated with the same
methods. The DAF values differ because the area of the windrows is different from the area of
the burial trench. When the windrows are built for 100, 500, 1000, and 10000 carcasses, the
DAFs are 315, 72, 38, and 5, respectively.
The USEPA analysis to develop DAFs uses soil infiltration rates rather than leachate volumes as
inputs to the unsaturated soil zone. The estimated radionuclide activity concentrations in the
leachate from the burial trench and compost windrow are the same, but the leachate volumes are
much different. As discussed in Section 3.2.2, this assessment assumes that the amount of
leachate from the compost windrow is 5% of the leachate volume from burial based on Glanville
et al. (2006) and Donaldson et al. (2012). To account for the difference in the well water, the
concentration estimated for the compost windrow is multiplied by 5%. The resulting base case
radionuclide activity concentrations for the composting option are shown in Table 14.
Table 14. Base Case Radionuclide Activity Concentrations in Well Water with Composting
of 100 Carcasses
Radionuclide
Radionuclide
Activity in
Carcass (Bq/kg)
Radionuclide
Activity in
Leachate (Bq/L)
DAF
Radionuclide
Activity in in
Well Water3
(Bq/L)
134Cs
500
486
315
7.1E-02
137Cs
500
499
315
7.9E-02
90 Sr
50
49.9
315
7.9E-03
131J
500
95.9
315
6.4E-06
a Estimates include radioactive decay over 90 days of travel from the source to the well.
Abbreviations: DAF = dilution attenuation factor(s).
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3.3.2. Concentrations in Surface Soil
Estimates of the radionuclide activity concentrations in finished compost were presented in Table
8. Using those values, radionuclide activity concentrations are estimated in surface soil following
application of the compost at a location on site. The rate of compost application to soil is based
on an agronomic nutrient addition consistent with calculations for the previous assessment
scenarios. Based on those calculations, the estimated area over which the finished compost can
be applied is about 4 hectares (ha) (-40,000 m2 or 10 acres [ac]). This amounts to an application
rate of about 24 dry tonnes of compost per hectare for the base case (i.e., 100 carcasses). The
compost application areas with 100, 500, 1,000, and 10,000 carcasses are 3.9, 19.7, 39.5, and 395
ha, respectively.
To estimate radionuclide concentrations in soil at the compost application site, the total
radionuclide activity content of the finished compost is divided by the application area for the
amount added per unit area(i.e., Bq/m2 soil). These values are then used to estimate
concentrations in surface soil with Equation 3.5 (below) from USEPA's (2005)HHRAP for
Hazardous Waste Combustion Facilities.2 The Human Health Risk Assessment Protocol
(HHRAP) is a peer-reviewed environmental modeling framework developed, refined, and used
by USEPA's Office of Resource Conservation and Recovery to estimate chemical transport of
chemicals released to air from a point source and their subsequent fate and transport in soil,
surface water, and terrestrial plants and animals. Although developed to model chemical
concentrations, the equations used here are valid for radionuclide activity concentrations. In
Equation 3.5, the total radioactivity addition with compost is mixed with the surface soil layer.
The resulting estimate, Cs, is the concentration radio activity in Bq per kg bulk soil at the
application location.
Cs = (¦vDpt) / (Zs * BD) (Eqn. 3.5)
where:
Cs = Radionuclide activity concentration in surface soil, Bq/kg
vDpt = Total radioactivity addition, Bq/m2
Zs = Soil mixing zone depth (m)
BD = Soil bulk density, kg/m3
Soil parameter values used in these calculations are HHRAP default assumptions. Specifically,
HHRAP provides default assumptions for bulk-soil density at 1500 kg per m3 (93.6 pounds [lb]
per ft3) (surface soil, unsaturated) and mixing depth assumptions. The compost is assumed to be
tilled into the soil to a depth of 20 cm. Table 15 presents the estimated base case radionuclide
activity concentration in soil.
2 Further information on HHRAP is available at: https://archive.epa.gov/epawaste/hazard/tsd/td/web/html/risk.html.
20
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Table 15. Estimated Radionuclide Activity in Finished Compost, Base Case
Radionuclide
Radionuclide Activity
Levels in Finished
Compost (Bq/kg dw)
Chemical Application
Rate (Bq/m2)
Concentration in Soil
Afite r Application
(Bq/kg)
134Cs
1.9E+02
4.5E+02
1.5
137Cs
2.3E+02
5.6E+02
1.9
90 Sr
2.3E+01
5.6E+01
0.2
131J
1.7E-07
4.2E-07
1.4E-09
Abbreviations: dw = dry weight; m2 = square meter(s).
With larger numbers of carcasses, the radioactivity in soil is the same as the base case if the
amount of finished compost and the area of compost application increase in direct proportion.
Radioactivity in soil does change when the initial level of radioactivity changes. For example,
with a 10-time increase in the 134Cs radioactivity, the concentration in soil will increase 10 times
as well, assuming that the application rate is still determined from the nutrient content of the
compost.
3.4. Exposure Estimation
With the goal of comparing exposures among carcass management options, exposure pathways,
and radionuclides, all exposures are normalized to human health benchmarks. Health-based
benchmarks are concentration- or dose-based estimates of the exposure level below which
adverse health effects are not expected. This section identifies the benchmark chosen for the
assessment and describes how the radionuclide activity concentration estimated in Section 3.3
are compared with them.
3.4.1. Human Health Benchmarks
Exposure-limiting benchmarks for radiation have been issued by many countries and by
international organizations for nuclear safety. Table 16 shows relevant standards issued by U.S.
and international agencies. In this assessment, radiation exposure can occur via the use of
contaminated groundwater in the home or pathways associated with contamination in on-site
soil.
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Table 16. Overall Limits (Emergency and Non-emergency) for Human Exposures to
Radiation
Exposure
Medium
Benchmark
Radioactive Material
Level of Exposure
Reference
Drinking
Maximum Contaminant
Level (MCL)
Beta/photon emitters
4 mrem/year over
70-year lifetime
USEPA 2001
Water
WHO Guidelines for
Drinking Water
137Cs, 131I,90Sr
10 Bq/L
IAEA 2016
Derived Intervention
90 Sr
160 Bq/kg food
USFDA 2004,
137Cs, 134Cs
1,200 Bq/kg food
Levels (DILs)
USFDA 2015
Foods
131I
170 Bq/kg food
FAO/WHO Codex
1311,90 Sr
1,000 Bq/kg food
IAEA 2016
Alimentarius Guidelines
137Cs, 134Cs
100 Bq/kg food
Soil
[no names]
Gamma radiation
No more than 2
times background
USEPA 2013
All
Annual Occupational
limit
AH
50 mSv
Dennison2016
Full references are at the end of the report. Abbreviations: FAO = Food and Agriculture Organization of the United
Nations; IAEA = International Atomic Energy Agency; MCL = maximum contaminant level; mrem = millirem(s);
mSv = millisievert(s); USEPA =U.S. Environmental Protection Agency; USFDA =U.S. Food and Drug
Administration; WHO = World Health Organization.
Benchmarks for Groundwater
Table 16 includes two benchmarks for radionuclides in drinking water. For a radiological
emergency in the US, the most relevant of these is the Maximum Contaminant Level (MCL)
established by USEPA as a legal limit applicable to public water systems. The MCL value
shown, 4 mrem/year, applies to radiation exposure from beta- and gamma-emitting
radionuclides, which include all four of the radionuclides included in the assessment. USEPA
has issued a separate MCL for alpha-emitting radionuclides, and MCLs specific to uranium and
radium.
The MCL for beta- and gamma-emitters is an effective dose of radiation to the whole body or
any organ from radionuclides ingested in the course of a single year. Because the ingested
radionuclides may stay in the body, the dose is based on the radiation that will be received by an
adult over the next 50 years. If multiple emitters are present, the sum of their doses must not
exceed the MCL. USEPA first identified 4 mrem/yr as a regulatory level for beta- and gamma-
emitters in 1976 and retained it as the MCL under later rules, most recently in 2000 (USEPA
2000). The MCL is in millirem, a unit commonly used in the U.S. The equivalent level in
international units is 0.04 millisieverts (mSv) or4.0E-5 Sv.
To help public water systems and state regulators monitor compliance with the MCL, the
USEPA calculated radionuclide activity concentrations equating to 4 mrem/yr for 179 man-made
individual beta particle and photon emitters (USEPA 2002). Table 17 lists the radioactivity
22
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concentrations for the four radionuclides in this assessment. Also shown in Table 17 are
USEPA's estimates of the cancer risks associated with drinking water exposure for each of the
179 radionuclides at 4 mrem/yr.
Table 17. Radionuclide Activity Concentrations for Maximum Contaminant Level (MCL)
Compliance (USEPA 2002)
Radionuclide
Radionuclide Activity Concentration
Estimated Risk
pCi/L
Bq/L
134Cs
20,000
740
1.29E-4
137Cs
200
7.4
2.14E-04
90 Sr
8
0.30
2.03E-05
131J
3
0.11
3.91E-06
Full reference at the end of the report. Abbreviation: pCi = picocurie(s).
In addition to the MCL, exposures from groundwater are evaluated relative to benchmarks
calculated for this assessment with USEPA's Preliminary Remediation Goals for Radionuclides
(PRG) Calculator.3 USEPA developed the PRG Calculator as an online tool to aid decision-
making at CERCLA (Comprehensive Environmental Response, Compensation, and Liability Act
[Superfund]) sites. PRGs can be used as initial cleanup levels for radiation, especially where
there are appropriate government cleanup levels already. The tool estimates PRGs as
radionuclide activity levels in abiotic or biotic media for several radionuclide exposure scenarios
(e.g., outdoor worker, home residents). Users can enter a target risk level (e.g., 1.0E-4) and site-
specific exposure factors or use EPA default values.
For this assessment, the PRG Calculator's farmer scenario is used to calculate benchmarks, in
Bq/L, for water exposure pathways. The PRGs are based on a target risk level of 1.0E-04, which
is consistent with both the MCL and risk specific doses for chemical exposure in the natural
disaster and chemical emergency assessments.
The farmer scenario includes four exposure routes that begin with contaminated water: ingestion
of drinking water, inhalation of aerosolized water, immersion (e.g., bathing), and ingestion of
irrigated produce, livestock, and fish. All water for farm products comes from contaminated
water on site, whether it be groundwater or surface water, and fish tissue concentrations are
estimated from the same water contamination. Fish ingestion is not included in this assessment
because the pathway must begin with surface water, not groundwater. All home-grown farm
products are either irrigated (produce) or watered (livestock) with contaminated well water.
Although the farmer scenario includes inhalation activities, such as showering and laundering
the PRG Calculator includes these activities only for radon and certain other volatile
radionuclides (USEPA 2016). The PRG Calculator does not include inhalation exposure for the
radionuclides in this assessment.
The PRGs for this assessment are calculated for one-year of exposure to adults and children age
1 to 2. Drinking water ingestion rates are 1.219 L/d and 0.332 L/d for adults and children,
respectively, the same values used in the natural disaster and chemical emergency assessments.
3 The PRG Calculator is an on-line tool available at: https://epa-pras.ornl.gov/radionuclides/
23
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All other exposure factors (e.g., inhalation rates, food ingestion rates) are default values, which
are documented in the PRG User's Guide (USEPA undated).
PRG calculations also require slope factors that are specific to each radionuclide and exposure
source. This assessment uses slope factors prepared by the Center for Radiation Protection
Knowledge at Oak Ridge National Laboratory (USEPA 2016),4 which are built into PRG
calculator. The slope factors for this assessment are shown in Table 18.
Based on the information describe above, groundwater PRGs calculated for this assessment are
presented in Table 19.
Table 18. Slope Factors for Radionuclide Ingestion
Radionuclide
Ingestion Slope Factor (Bq1)
Tap Water
Diet
Soil
134Cs
1.14E-09
1.40E-09
1.55E-09
137Cs
8.24E-10
1.01E-09
1.15E-09
90 Sr
1.51E-09
1.86E-09
2.33E-09
131J
1.23E-09
1.75E-09
3.31E-09
Abbreviations: Bq_1 = perbecquerel(s).
Table 19. Preliminary Remediation Goals for Radionuclides (PRGs) Calculated for
Groundwater Exposure
PRG (Bq/L)
Radionuclide
Drinking Wate r Inge s tion Only
All Pathways
Adult
Child 1-2
Adult
Child 1-2
134Cs
2.0E+02
7.2E+02
2.7E+01
5.0E+01
137Cs
2.7E+02
1.0E+03
3.3E+01
6.3E+01
90 Sr
1.8E+02
6.7E+02
4.5E+01
8.1E+01
131I
1.5E+02
5.5E+02
7.5E+00
1.7E+01
Benchmarks for Soil
Benchmarks for soil are calculated with the PRG Calculator, described above for groundwater.
The PRGs for soil are calculated with the farmer scenario, which includes exposure from
incidental soil ingestion, external radiation from contaminants in soil, inhalation of fugitive dust,
and consumption of homegrown foods grown in contaminated soil. Ingestion of home-caught
fish is not included because the exposure route begins with sediment rather than surface soil (i.e.,
where compost has been applied). All exposure factors are the same as described above for the
calculating the groundwater PRGs, and the target risk is 1.0E-04.
A required input for calculating the soil PRGs is the area of soil contamination. As described in
Section 3.3.2, compost application areas are calculated for composting 100, 500, 1000, and
10000 cattle carcasses. The PRG calculator provides a list of areas to enter but does not allow the
4 A compendium of radionuclide dose coefficients prepared by the Oak Ridge National Laboratory is available at: https://epa-
dccs.ornl.gov/documents/SlopesandDosesMasterTableFinal.pdf
24
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custom areas to be entered. The areas entered in the PRG calculator were the available values
closest to the calculated compost application areas, as shown in Table 20.
PRGs calculated with the information discussed above are presented in Table 21. The PGRs are
not very sensitive to the area of soil contamination. The two largest contamination areas have the
same PRG values, and because they are the lowest (i.e., most conservative) values they are
selected to be the soil exposure benchmarks in this assessment.
Table 20. Compost Application Areas for Calculating Soil Preliminary Remediation Goals
for Radionuclides (PRGs)
Compost Application Area
Modeled Area of
Numbe r of Care as s es
Ha
Contamination
m2
(m2)
100
3.9
39,500
50,000
500
19.7
197,000
200,000
1,000
39.5
395,000
500,000
10,000
395
3,950,000
1,000,000
Abbreviations: Ha = hectares ;m2= square meter(s).
Table 21. Preliminary Remediation Goals for Radionuclides (PRGs) Calculated for Soil
Exposure
PRG (Bq/kg)
Radionuclide
50,000 m2
200,000 m2
500,000 m2
o
o
©
000 m2
Adult
Child*
1-2
Adult
Child
1-2
Adult
Child
1-2
Adult
Child
1-2
134Cs
1.3E+03
1.9E+03
1.1E+03
1.8E+03
1.1E+03
1.7E+03
1.1E+03
1.5E+03
137Cs
2.2E+03
3.9E+03
2.2E+03
3.9E+03
2.2E+03
3.9E+03
2.2E+03
3.9E+03
90 Sr
2.9E+02
7.2E+02
2.9E+02
7.2E+02
2.9E+02
7.2E+02
2.9E+02
7.2E+02
131J
4.0E+04
5.7E+04
3.8E+04
5.6E+04
3.8E+04
5.6E+04
3.8E+04
5.4E+04
*Child age 1-2 years
3.4.2. Exposure Metrics
In many health-based exposure and risk assessments, contaminant concentrations in exposure
media (e.g., drinking water, food) are used to calculate amount of contaminant ingested based on
ingestion rates, exposure durations, and other exposure factors. The resulting estimates (e.g.,
doses in mg/kg-d), are then evaluated relative to health benchmarks that reflect the inherent
toxicity of the contaminant.
In this exposure assessment, it is not necessary to estimate ingestion exposure doses, because the
all of the benchmarks discussed above are in environmental media concentration units (e.g.,
Bq/L). These benchmarks can be compared directly to the radionuclide activity concentrations in
water or soil presented in Section 3.3. The concentration-based benchmarks already account for
ingestion rates as well as the inherent cancer-causing potential of the radionuclides.
25
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4. Results and .Discussion
This section presents the results of the radiological exposure assessment. Section 4.1 discusses
exposures with the base case assumptions. Section 4.2 examines how the exposure estimates
change with variation of the base case assumptions. Section 4.3 compares all seven off-site and
on-site carcass management options in terms of their utility and potential for radiological
exposures. Section 4.4 identifies the major sources of uncertainty in the assessment and evaluates
how they affect the quantitative exposure estimates.
4.1. Base Case Exposure Assessment
Base case exposures are evaluated on a relative basis, comparing estimates among management
options, exposure pathways, and radionuclides. To facilitate these comparisons, the estimated
radionuclide activity concentrations in groundwater and soil presented in Section 3.3 are divided
by radionuclide-specific, risk-based media concentration benchmarks identified in Section 3.4.
These ratios are referred to as "ranking ratios."
4.1.1. Groundwater Pathways
The base case for this assessment radiological exposure following burial or composting 100
cattle carcasses under the site and carcass management scenario assumptions are identified in
Section 3.2. Base case levels of radionuclide contamination are based on contamination observed
in beef and dairy following the Fukushima accident, as described in Section 3.1.
The base case results are presented in Table 22. The results are ranking ratios calculated by
dividing estimated radionuclide activity concentrations by health-based benchmark
concentrations. The exposure concentrations are normalized to benchmarks in this way for risk-
based comparisons (e.g., among management options, radionuclides). However, the results
should not be interpreted as actual levels of risk because the comparative assessment is based on
several assumptions (e.g., distance to the well) that are likely to differ from actual sites.
Ranking ratios for groundwater exposures are consistently higher with burial than composting, as
shown in Table 22 and Figure 1. This is because the burial trench releases much more leachate
than the compost windrow. Estimates for the two options begin with the same leachate
concentrations and well placement relative to the source. However, dilution attenuation in soil
and groundwater differs between the options owing to the DAF approach from USEPA (1996)
used to estimate well water concentrations. In the EPACMTP modeling to develop the DAFs,
increasing the source area increased the infiltration rate, which lowered the DAF, but also
increased the mixing zone depth, which increased the DAF (USEPA 1996). The Monte Carlo
modeling that produced the DAFs determined the balance of these relationships.
26
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Table 22. Ranking Ratios with the Base Case3
Groundwater
Soil
Base Case
Contamination
(Bq/L)
Rankin"
Ratio
with
MCL
Ranking Ratio with PRG
Ranking Ratio
with PRG
Radionuclide
Water Ingestion
Only
All Water
Pathways
Adult
Child"
1-2
Adult
Child
1-2
Adult
Child
1-2
Burial
134Cs
500
6.9E-04
2.6E-03
7.0E-04
1.9E-02
1.0E-02
np
np
137Cs
500
7.6E-02
2.1E-03
5.7E-04
1.7E-02
8.9E-03
np
np
90 Sr
50
1.9E-01
3.8E-04
1.0E-04
7.5E-03
3.2E-03
np
np
131J
500
4.1E-04
2.5E-07
6.8E-08
1.0E-06
5.7E-07
np
np
Composting
134Cs
500
9.6E-05
3.6E-04
9.8E-05
2.7E-03
1.4E-03
1.2E-03
8.1E-04
137Cs
500
1.1E-02
2.9E-04
7.9E-05
2.4E-03
1.2E-03
8.6E-04
4.7E-04
90 Sr
50
2.7E-02
5.3E-05
1.4E-05
1.1E-03
4.5E-04
6.4E-04
2.6E-04
131I
500
5.8E-05
3.5E-08
9.5E-09
1.4E-07
7.9E-08
3.5E-14
2.5E-14
Acronyms: MCL = Maximum Contaminant Level, np = radionuclide is not present,PRG = Preliminary Remediation
Goals for Radionuclides.
a The base case includes 100 cattle carcasses and carcass contamination levels that vary by radionuclide.
Contamination levels are discussed in Section 2.2.
b Child age 1-2 years.
27
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l.E+02
¦
100
carcasses
500
carcasses
1000 10000
carcasses carcasses
100
carcasses
500
carcasses
1000
carcasses
10000
carcasses
Burial
Composting
• Cesium-134 •Cesium-137 • Strontium-90 • lodine-131
Figure 1. Groundwater exposure ranking ratios for burial and composting by scale of
mortality, with Maximum Contaminant Level (MCL) benchmark.
Ranking ratios for groundwater exposure are calculated for two types of benchmark, the MCL
and PRGs calculated for this assessment (see Section 3.4.1). While there is a single set of
constituent-specific regulatory benchmarks for the MCL, PRGs are calculated separately for
adults and children and separately for with or without pathways other than drinking water
ingestion. The PRGs with the exposure basis most directly comparable to the MCL is water
ingestion only by an adult. As shown in Table 22, the base case activity concentrations in
groundwater estimated for all four radionuclides are below (i.e., have ranking ratios below 1)
both types of benchmark. With the exception of13 4Cs, each of the radionuclides is closer to
exceeding the MCL than the PRG. Differences between the benchmarks, and the estimated
radioactivity concentrations relative to the benchmarks, are explained by differences in how the
benchmarks were derived. For example, while the PRGs all represent a target risk level of 1.0E-
04, the MCLs all represent the same effective (i.e., 4 mrem/yr) dose but different levels of risk
(see Table 17). In addition, the MCL is based on a water ingestion rate of 2 L/d and PRGs are
based on more recent age-specific ingestion rates.
Considering the ranking ratios with MCLs, 137Csand 90Srare about two orders of magnitude
closer to the benchmark than 134Csand 131I. This pattern roughly corresponds to differences in
half-lives; 137Csand 90Srhave half-lives of 30.2 and 28.8 years, respectively, and 134Csand 131I
have much shorter half-lives (2.1 years and 8 days, respectively). When internally absorbed (e.g.,
from ingestion), radionuclides with longer half-lives will remain active longer in the body.
However, the pattern among the radionuclides may be affected by other factors including
differences in the methods used to calculate the benchmarks. This might explain why the
position of134Cs differs among the four radionuclides when compared to the MCL and PRG
benchmarks, as seen by comparing Figures 1 and 2.
28
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o
'+¦»
ro
l.E+01
l.E+OO
l.E-01
l.E-02
l.E-03
bfl
c
1* l.E-04
C
ro
oc
l.E-05
l.E-06
l.E-07
l.E-08
8
e
e
8
100 500 1000 10000
carcasses carcasses carcasses carcasses
Burial
100 500 1000 10000
carcasses carcasses carcasses carcasses
Composting
4 Cesium-134 •Cesium-137 • Strontium-90 •lodine-131
Figure 2. Groundwater exposure ranking ratios for burial and composting by scale of
mortality, with Preliminary Remediation Goals for Radionuclides (PRG) benchmark
(adult, drinking water only).
Calculation of the PRG benchmarks includes chemical-specific properties, such as biotransfer
factors and partitioning coefficients. Estimation of groundwater concentrations include
radioactive decay constants, but no other chemical-specific properties. Significantly, the DAFs
that relate radionuclide activity concentrations in leachate to concentrations in well water, are not
chemicals specific. For this reason, exposure to cesium radionuclides is likely to be
overestimated because cesium has a low mobility in surface soil compared to other metals and
usually does not migrate below a depth of 40 cm (ATSDR 2004a). However, groundwater
contamination with cesium could occur if, for example, cracks or macro-pores in the soil provide
a pathway to groundwater.
As discussed in Section 3.4.1, the PRG benchmarks were calculated with the USEPA's online
PRG Calculator. The tool provides options to create site-specific PRG values by choosing
receptor and setting scenarios, exposure pathways, radionuclides of concern and other factors.
This assessment uses PRGs for two scenarios, which are labeled as "Water Ingestion Only" and
"All Groundwater Pathways" in Table 22 and Figure 3. The "Water Ingestion Only" PRGs are
based on exposure to farm residents who drink well water with radionuclide contamination and
receive no other radiation from carcass management activities. This scenario is included for
comparisons with MCLs, which are based only on drinking water ingestion. The "All
Groundwater Pathways" PRGs are calculated for farm residents who drink contaminated well
water, and are also exposed by immersion (e.g., bathing dishwashing), and ingesting home-
grown foods irrigated or watered with the groundwater.
29
-------
O l.E-02
ro
cc
|2P l.E-03
#2 l.E-04
100 500
carcasses carcasses
1000 10000
carcasses carcasses
100 500 1000 10000
carcasses carcasses carcasses carcasses
Drinking Water Ingestion Only All Groundwater Pathways
• Cesium-134 •Cesium-137 • Strontium-90 •lodine-131
Figure 3. Groundwater exposure ranking ratios for burial by scale of mortality, with
Preliminary Remediation Goals for Radionuclides (PRG) benchmark.
As expected ranking ratios based on water ingestion only PRGs are higher than ranking ratios
based on PRGs for water ingestion and additional pathways. The ranking ratios differ by about
an order of magnitude or less, as seen in Figure 3. Table 23 shows the relative contributions of
the groundwater exposure pathways for each radionuclide, and for adults and children. For all
four radionuclides, ingestion of homegrown produce is the largest source of exposure for both
adults and children. Variations between pathways, radionuclides, and age groups in Table 23 are
attributable to differences in chemical fate properties and age-specific ingestion rates.
Table 22 shows that ranking ratios groundwater exposure are higher for adults than children. In
contrast, in chemical exposure assessment, children often are more highly exposed than adults
because they tend to ingest more (e.g., food, soil) per unit body weight. Chemical exposure doses
are typically normalized to body weight (e.g., mg chemical per kilogram body weight per day).
For radiation exposures, a dose estimate is an amount of energy not an amount of radioactive
material (ATSDR 1999), and exposures are not normalized to body weight. The radiation
exposure estimates are higher for adults because adults have higher ingestion rates (e.g., L/day)
than children, and thus receive more internal radiation from a year's worth of ingestion.
30
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Table 23. Contribution of Groundwater Exposure Pathways to Preliminary Remediation
Goals for Radionuclides (PRGs)
Radionuclide
Drinking Water
Homegrown
Produce
Homegrown
Livestock
Immersion
Adult
134Cs
14%
75%
11%
<1%
137Cs
12%
78%
10%
<1%
90 Sr
5%
94%
1%
<1%
131J
25%
61%
14%
<1%
Child Age 1-2 Years
134Cs
7%
77%
16%
<1%
137Cs
6%
79%
14%
<1%
90 Sr
3%
95%
1%
<1%
131I
12%
59%
28%
<1%
4.1.2. Soil Pathways
Exposure to radionuclides in soil is evaluated only for the composting option, and specifically to
surface soil where finished compost is amended. It is possible that the soil in the footprint of the
compost windrows might have higher levels of radionuclides, but this was not included in the
exposure assessment. The ranking ratios for the soil exposure pathways are calculated by
dividing the estimated radionuclide activity concentrations in soil by PRGs. As discussed in
section 3.4.1, the PRGs are based on a target risk level of 1.0E-04 and exposure from incidental
soil ingestion, external radiation from contaminants in soil, inhalation of fugitive dust, and
consumption of homegrown foods grown in contaminated soil.
Table 24 presents the base case ranking ratios, along with the estimated radionuclide activity
levels in finished compost and soil. All ranking ratios are below 1. Differences among the
radionuclides result from chemical-specific fate inherent health risk properties included in the
PRG calculator, as well as differing radioactive decay rates. 1311 radioactivity in compost and soil
is much lower than estimated for the other three radionuclides because of its much shorter half-
life of eight days.
4.2. Uncertainty Analysis
The uncertainty analysis for the radiological emergency exposure assessment examines two
factors that, in the event of an actual emergency, could vary greatly from the base case. These are
the scale of mortality (i.e., the number of carcasses to be managed) and the level of
contamination. Section 4.4 discusses how the exposure assessment is affected by a number of
other scenario assumptions and uncertainties in the data and methods.
4.2.1. Scale of Mortality
In the base case scenario, the radiological emergency results in 100 contaminated carcasses that
must be managed. This section shows how the radionuclide exposures, as indicated by ranking
ratios, would change with 500, 1,000, and 10,000 carcasses.
Figures 1 and 2 show the ranking ratios for groundwater pathways using the MCL and PRGs,
respectively, as benchmarks. Results for burial and composting are included in the site-by-side
charts. The ranking ratios increase with the scale of mortality, but less than proportionally. For
31
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example, with 5, 10 and 100 times more carcasses, the ranking ratios for all radionuclides and
both management options increase approximately 4.4, 8.3, and 69 times, respectively. The
proportionality is a function of the DAFs used to estimate radionuclide activity concentrations in
well water relative to leachate, and as discussed in Section 3.3.1. The DAFs reflect variables that
are independent of chemical-specific properties. For example, USEPA determined that the DAFs
are sensitive to the size of the leachate source and thus used source area as a basis for identifying
site-specific DAFs (USEPA 1996). The development of that approach is discussed in Section
3.3.1 and further in Soil Screening Guidance: Technical Background Document (USEPA 1996).
32
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Table 24. Base Case Ranking Ratios for Soil Exposure Pathways Following Compost Application
Radionuclide
Amount of
Finished
Compost (MT
dw)
Total
Radioactivity
at End of
Composting
(Bq)
Radioactivity
in Finished
Compost
(Bq/kg dw)
Compost
Application
Area(m2)
Radioactivity
Application
Rate (Bq/m2)
Concentration
in Soil After
Application
(Bq/kg)
Ranking
Ratio with
PRG, Adult
Ranking Ratio
with PRG,
Child
134Cs
96
1.8E+07
1.9E+02
39,498
452
1.5
1.2E-03
8.1E-04
137Cs
96
2.2E+07
2.3E+02
39,498
556
1.9
8.6E-04
4.7E-04
90 Sr
96
2.2E+06
2.3E+01
39,498
56
0.2
6.4E-04
2.6E-04
1311
96
1.7E-02
1.7E-07
39,498
4.24E-07
1.4E-09
3.5E-14
2.5E-14
Abbreviation: dw = dry weight, MT = metric tons,PRG = Preliminary Remediation Goals for Radionuclides. Child age 1-2 years.
33
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4.2.2. Level of Contamination
The base case radionuclide activity concentrations in the carcasses are based on the upper ranges
of contamination observed following the Fukushima accident. The scale of contamination
resulting from the Fukushima accident was affected by the amount of radionuclide released, the
manner in which the releases occurred, and many site-specific factors (e.g., meteorology,
proximity of potentially affected livestock). In the event of a similar accident in the future,
changes in any of these factors could result in higher or lower levels of contamination.
To examine how exposure estimates change with varying levels of contamination, this
assessment includes four starting contamination levels for each radionuclide. Four levels of
contamination include one that is below the base case level, and two levels that are higher. For
the cesium and strontium radionuclides, the higher levels are 10 and 100 times greater than the
base case, and for 131Ithe higher levels are 2 and 10 times greater. The rationales for the base
case, lower, and higher contamination levels are discussed in Section 3.3.1.
Tables 25 through 28 show the ranking ratios with increasing levels of contamination for
groundwater exposure from the burial or composting of 100 carcasses. The results for the four
radionuclides are presented in separate tables because the levels of contamination differ. For all
four radionuclides and both management options, the estimated exposures, and therefore ranking
ratios increase in equal proportion to the level of contamination (i.e., a 100 times increase in the
initial contamination level results in 100 times greater exposure).
The PRG ranking ratios in Tables 25 through 28 are based on the "All Groundwater Pathways"
estimates. The development of these benchmarks includes pathways and processes, such as
uptake by plants and livestock, which are not addressed by the MCLs. Because both types of
benchmarks increase in the same proportional rate with the level of contamination, it is evident
that the fate and transport algorithms used in USEPA's PRG Calculator are not concentration
dependent.
Although not shown, the relationship above between level of contamination and ranking ratios
for groundwater exposure also applies to soil exposure pathways associated with compost
application.
Table 25. Ranking Ratios with Increasing 134Cs Contamination
Carcass Contamination,
Ranking Ratio with
Ranking Ratio with PRG
134Cs (Bq/kg)
MCL
Adult
Child
Burial
50
6.9E-05
1.9E-03
1.0E-03
500
6.9E-04
1.9E-02
1.0E-02
5,000
6.9E-03
1.9E-01
1.0E-01
50,000
6.9E-02
1.9E+00
1.0E+00
Composting
50
9.6E-06
2.7E-04
1.4E-04
500
9.6E-05
2.7E-03
1.4E-03
5,000
9.6E-04
2.7E-02
1.4E-02
50,000
9.6E-03
2.7E-01
1.4E-01
Abbreviation: MCL = Maximum Contaminant Level, PRG = Preliminary Remediation Goals for Radionuclides.
34
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Table 26. Ranking Ratios with Increasing 137Cs Contamination
Carcass Contamination,
Ranking Ratio with
Ranking Ratio with PRG
137Cs (Bq/kg)
MCL
Adult
Child
Burial
50
7.6E-03
1.7E-03
8.9E-04
500
7.6E-02
1.7E-02
8.9E-03
5,000
7.6E-01
1.7E-01
8.9E-02
50,000
7.6E+00
1.7E+00
8.9E-01
Composting
50
1.1E-03
2.4E-04
1.2E-04
500
1.1E-02
2.4E-03
1.2E-03
5,000
1.1E-01
2.4E-02
1.2E-02
50,000
1.1E+00
2.4E-01
1.2E-01
Abbreviation: MCL = Maximum Contaminant Level, PRG = Preliminary Remediation Goals for Radionuclides.
Table 27. Ranking Ratios with Increasing 90Sr Contamination
Carcass Contamination,
Ranking Ratio with
Ranking Ratio with PRG
90Sr (Bq/kg)
MCL
Adult
Child
Burial
5
1.9E-02
7.5E-04
3.2E-04
50
1.9E-01
7.5E-03
3.2E-03
500
1.9E+00
7.5E-02
3.2E-02
5,000
1.9E+01
7.5E-01
3.2E-01
Composting
5
2.7E-03
1.1E-04
4.5E-05
50
2.7E-02
1.1E-03
4.5E-04
500
2.7E-01
1.1E-02
4.5E-03
5,000
2.7E+00
1.1E-01
4.5E-02
Abbreviations: MCL = Maximum Contaminant Level, PRG = Preliminary Remediation Goals for Radionuclides.
Table 28. Ranking Ratios with Increasing 131I Contamination
Carcass Contamination,
Ranking Ratio with
Ranking Ratio with PRG
131I (Bq/kg)
MCL
Adult
Child
Burial
o
o
8.3E-05
2.0E-07
1.1E-07
500
4.1E-04
1.0E-06
5.7E-07
1,000
8.3E-04
2.0E-06
1.1E-06
5,000
4.1E-03
1.0E-05
5.7E-06
Composting
o
o
1.2E-05
2.8E-08
1.6E-08
500
5.8E-05
1.4E-07
7.9E-08
1,000
1.2E-04
2.8E-07
1.6E-07
5,000
5.8E-04
1.4E-06
7.9E-07
Abbreviation: MCL = Maximum Contaminant Level, PRG = Preliminary Remediation Goals for Radionuclides.
35
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In this assessment, the four radionuclides are evaluated independently of each. However, if
multiple radionuclides were present, the total beta/gamma radiation would determine compliance
with the MCL. It should be noted that an MCL applies to public water systems, not private wells
as included in this assessment scenario. The MCL is included in the assessment to serve as a
basis of comparison and evaluation of the findings.
The cesium monitoring data from the Fukushima accident measured total cesium radiation (i.e.,
the total of all radioisotopes). Those data were used to select the base case radioactivity level that
is used for each of the two cesium radioisotopes.
4.3. Exposure Assessment Summary
The exposure assessment of livestock carcass management options in the event of a radiological
emergency follows related assessments for carcass management following natural disasters,
foreign animal disease outbreaks, and chemical emergencies. Each of those assessments
concluded with a two-tiered ranking of the seven on-site and off-site management options. The
Tier 1 assessments compared the off-site to the on-site options qualitatively, because only the
off-site options were not included in the quantitative exposure assessments. The Tier 1
assessments concluded that, in general, off-site management options are more protective of
human health and the environment than on-site option, because all releases to the environment
(e.g., incinerator emissions to air, rendering facility discharge to surface water) are restricted by,
and are assumed to comply with, applicable environmental regulations. The quantitative Tier 2
rankings showed that the potential exposures from on-site options depend on the type of
hazardous agent and site-specific exposure pathways.
The ranking of management options in the event of a radiological emergency is primarily
qualitative, because two of the on-site options, as well as the three off-site options, were not
quantitatively assessed. As in the previous assessments, exposures from the off-site options were
not modeled, because all releases to the environment from those options are controlled and
regulated under federal environmental laws (e.g., the Clean Air Act, the Atomic Energy Act). As
discussed in Section 2.3, the two on-site options excluded from the radiological exposure
assessment are open burning and air-curtain burning, the two combustion-based options.
Table 29 presents the qualitative ranking of the seven management options. Composting is
divided to distinguish exposures associated with the compost windrow and application of
finished compost. The carcass management options are divided into two groups, containment and
treatment options. The containment options limit the release and dispersal of, and exposure to,
chemical or biological hazards posed by the carcasses. The treatment options are intended to
reduce the volume of the carcasses and to reduce their noxious, infectious, or toxic properties.
Composting is listed with the containment options in Table 29 but can be considered a treatment
option since most microbes are inactivated.
Radioactivity is not reduced by the carcass treatment options included in Table 29. In each case,
treatment might spread or worsen contamination at the carcass management site. Containment
options control the release of radionuclides to environmental media and human health exposure
pathways. Based on this difference, the containment options, as a group, are ranked higher (i.e.,
more protective) than the treatment options.
36
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The containment options are listed in Table 29 in descending order of their effectiveness. Off-
site facilities designed and permitted to manage radioactive waste include features (e.g.,
impervious liners, overpacking in containers) that would not be included in the on-site options if
designed as described in Section 3. Although off-site containment would be the most effective
containment option, it is likely to be impractical, particularly for a very large volume of
contaminated carcasses. For example, decomposition progresses rapidly in the first week after
death and the deteriorating condition of the carcasses would make them increasingly difficult to
transport and manage at a distant facility. Currently, there are only four licensed low-level
radioactive waste landfills in the U.S., in Barnwell, South Carolina; Richland, Washington;
Clive, Utah; and Andrews, Texas (USNRC 2016).
37
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Table 29. Qualitative Ranking of Livestock Carcass Management Options - Containment vs. Treatment Options
M image ment Type *
Manage me
nt Option
Summary of Potential Exposures
Controls and Limits to
Environmental Releases
Rank 1: Containment
Options
Containment options prevent
or reduce the release and
dispersal of contaminants,
Off-site
Landfilling
¦Managing carcasses at an off-site facility authorized
to accept radioactive waste would contain the
radioactivity and eliminate or reduce exposures.
¦Capacity, distance, and cost might limit feasibility.
¦Facilities authorized to manage
radioactive wastes are designed and
operated with regulatory oversight to
effectively contain radioactivity.
including radionuclides and
particles containing
radionuclides. These options
could reduce the bulk of the
carcasses.
On-site
Burial
¦Without proper siting, on-site burial has the potential
to contaminate groundwater with mobile
radionuclides, particularly with longer half-lives.
¦A thick depth of compacted cover soil will block most
radiation at the surface.
¦Compliance with regulatory siting
limitations (e.g., minimal depth to
groundwater) will limit exposures.
¦Lining the burial trench protects
groundwater from contamination but
might be infeasible in the time
available to before carcasses begin
to decompose.
On-site
Composting
Windrow
¦A properly constructed windrow would produce a
minor amount of leaching, and less potential
exposure, compared to burial.
¦Bulking material absorbs most of the leachate, would
block most beta particles, but provide limited
blockage of gamma radiation.
¦ Groundwater contamination can be
reduced or eliminated by building
the windrow on an impervious
surface and containing runoff.
¦For radionuclides with relatively
short half-lives, the windrow can be
left in place until radioactivity
declines to acceptable levels.
¦Composting can be used to reduce
the moisture of radioactive materials
before further management.
¦External exposure to radioactivity
from the windrow can be reduced by
limiting time near it.
On-site
Compost
Application
¦Composting does not destroy radioactivity and most
of the radionuclide contamination will be present in
the finished compost.
¦Compost can be buried, landfilled,
or otherwise contained to avoid
surface exposure pathways.
38
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M image ment Type *
Manage me
nt Option
Summary of Potential Exposures
Controls and Limits to
Environmental Releases
¦Ingestion exposure can occur if compost is applied to
soil where crops or livestock are farmed or where soil
can erode to surface water.
Rank 2: Treatment Options
Treatment is intended to
reduce the volume of the
carcasses and to reduce their
noxious, infectious, or toxic
Off-site
Incineration
¦Commercial waste incinerators are not licensed to
accept radioactive waste.
¦Ifincineration is allowed, air pollution control
equipment would provide more protection than
uncontrolled combustion options.
¦Incineration of radioactive carcasses
is unlikely due to unavailability.
properties. Radioactivity is
not destroyed by treatment.
Off-site
Rendering
¦Although air and water releases are regulated,
rendering facilities are not designed or permitted to
process radioactive livestock, making this option
unlikely.
¦Radionuclides are not destroyed and would remain in
rendering products and wastes.
¦If approved, rendering could be used
to reduce the moisture, weight, and
volume of radioactive materials
before further management.
On-site
Open
Burning and
Air-curtain
Burning
¦ Combustion is not effective in reducing the
radioactivity levels in a waste stream, and
contamination would be spread by uncontrolled air
emissions.
¦Exposure could result from contamination of air, soil,
water, and biota.
¦Combustion ash would contain concentrated
radiation.
¦ Open burning and air-curtain
burning include no pollution control.
¦ Off-site disposal might be required
for combustion ash.
*Rank 1 are the options least likely to result in exposure.
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With on-site burial, the carcasses are isolated from exposure pathways on the land surface and
the most likely exposure pathways begin with leaching to soil and groundwater. Leaching from
the compost windrow also has the potential to contaminate groundwater, but the amount of
leachate released, and the resulting exposure, is much lower from composting than from burial
(Section 4.2 are lower). Above ground, the carcasses in the windrow are more vulnerable to
disturbance (e.g., by animals) than when they are buried, although carcasses are rarely disturbed
by animals in well-constructed windrows.
While burial is intended to be a final and permanent destination for the carcasses, the compost
windrow is a temporary management location. Depending on its radioactivity, the finished
compost might be buried on-site, sent to an off-site landfill, amended to soil, or some other
option. If a radionuclide contained in the compost has a lengthy half live (e.g., years), then
further containment will be needed.
The quantitative exposure assessment for the burial and composting options included a number
of conservative assumptions that are likely to overestimate drinking water exposure. For
example, a complete drinking water exposure pathway would require a domestic water-supply
located down gradient from the source in the direction of groundwater flow. In addition, the
DAF approach developed by USEPA to estimate contaminant concentrations at a nearby well
does not account for chemical-specific properties and thus overestimates exposures for relatively
immobile radionuclides (e.g., 134Cs and 137Cs). Despite these conservative aspects of the
approach, the exposures estimated for both options were below benchmarks except with the
management of 10,000 carcasses or carcasses with the highest assessed levels of contamination.
A significant radiological emergency in the United States would be largely unprecedented, and
carcass management might be subsumed in a broader and unprecedented response plan (see
Appendix B). For example, it is possible a specialized radioactive waste disposal unit or
immobilization treatment system would be constructed at the site, or that the site would be
designated as an exclusion zone and carcasses would be left unmanaged. These outcomes are
outside the scope of this assessment.
While the findings above can inform decision-making in the event of an actual radiological
emergency, managers should compare the scenarios and assumptions of this assessment to site-
specific circumstances. In doing so, decision-making can be aided further by the following
information provided in this report:
¦ Radiation facts - Section 2.2 describes the different types of radioactivity and identifies the
U.S. and international units used to characterize radiation and radiation doses. The report
also describes concepts in radiological exposure assessment (e.g., internal and external
doses) that differ from chemical exposure assessment.
¦ Conceptual models - Conceptual models for each management option, which are included
in Appendix A, identify the possible pathways by which humans might be exposed to
contamination.
¦ Environmental fate concepts - The description of radionuclide releases and environmental
fate estimation in Sections 3.2 and 3.2 identify factors (e.g., aquifer and well characteristics)
determine whether a complete exposure pathway actually exists at a particular site.
¦ Management option assumptions - Sections 3.2 and 3.3 identify assumptions to (e.g.,
compost burial trench dimensions, volume of finished compost) used to estimate
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environmental releases and exposures. These assumptions are from cited literature and can
be used for calculations for actual sites.
¦ Radioactive decay equations - The report provides equations to calculate radioactive
decay and describes how decay relates to the management options.
¦ Information and computational resources - Sections 3.3 and 3.4 identify information
resources and tools (e.g., USEPA DAFs, Oak Ridge National Laboratory (ORNL) radiation
dose conversion factors, the PRG Calculator) that can be useful for site-specific studies.
¦ Variability relationships - Section 4.2, as well as topics discussed throughout the report,
describe how exposures might differ at sites where scenarios and assumptions differ from
those assumed for this assessment.
¦ Mitigation - By describing the environmental releases and exposure pathways for the
management options, the report can be used to identify effective mitigation measures to
prevent or reduce radiation exposure.
To frilly understand the findings of this exposure assessment, it important to understand how the
assessment approach addresses unavoidable and inherent uncertainties. Section 4.4 identifies
three types of uncertainties in the assessment and describes how the findings are influenced by
the approaches and assumptions used to address them.
4.4. Uncertainly Summary
Tables 30 through 32 summarize three types of uncertainties in the exposure assessment:
¦ Parameters with Moderate to High Natural Variation (Table 30)- These uncertainties
pertain to parameters for which substantial variation exists across the United States, and the
assessment uses value selected either to be nationally representative, to be health protective
(i.e., overestimate exposure), or for another reason. The table lists the magnitude (low,
medium, high) and direction (under- or overestimate) of bias in the exposure estimates for
each one.
1 Uncertain Parameter Values or Models (Table 31) - These include parameters for which
limited data were available to calculate a central tendency value or to estimate likely
variation across conditions possible in the country. Uncertainty is characterized as low,
medium, or high. By definition, the direction of bias is unknown.
1 Simplifying Assumptions (Table 32)-The assessment requires a number of "simplifying
assumptions" to compare management options relative to each other within a reasonable
level of effort. The table identifies the magnitude (low, medium, or high) and direction
(under- or overestimate) of bias introduced by the assumptions.
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Table 30. Moderate to High Natural Variation in Parameter—Potential Bias from Selected Values
Key Topic
Se le cted Parame ter Value
Bias
Rationale
Radiological Emergency Scenario
Scale of
Mortality
¦The assessment assumes a "base case"
mortality of 100 cattle at one farm with a
total weight of 50 short tons.
¦The base case mortality matches the earlier
assessments for the natural disaster and
foreign animal disease outbreak scenarios.
¦Larger scale losses of 500, 1,000, and 10,000
are also evaluated.
Possibly High
Underestimate
¦The base case scale of mortality could be "small"
relative to mass mortality or euthanasia (e.g.,in the
event of wide-spread feed contamination).
¦Larger scale losses could make some management
options technically infeasible (e.g., due to resource
availability)
¦Large-scale mortalities could exceed the capacity of
off-site management facilities.
¦Large scale mortality might require periods of
temporary carcass storage due to capacity or resource
limitations, which increases the potential for exposures.
Site Setting and Environmental Conditions
Groundwater
¦The assessment assumes that radionuclides
leached from the burial trench and compost
windrow can reach groundwater.
¦The groundwater is assumed to supply
domestic water well 100 m downgradient
from the source of leachate.
Variable
Overestimate
¦In the event of a radiological emergency, it is unlikely
that carcass management would be sited 100 m from a
domestic water well.
¦Although the domestic well exposure pathway is
possible, the domestic well would have to be shallow
enough to directly intersect leachate from surface
sources. In addition, well contamination would require
the well to be located down gradient (in the direction of
groundwater flow) from the source.
Dilution
Attenuation
Factors
¦The assessment uses DAFs developed by the
USEPAusing a Monte Carlo analysis of a
nationwide database of aquifer and well data.
The DAFs and the groundwater transport
methods do not include radionuclide-specific
mobility properties.
High
Overestimate
¦Exposure through groundwater pathways is likely to be
overestimated, particularly for cesium, which has a low
mobility in surface soil.
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Key Topic
Se le cted Parame ter Value
Bias
Rationale
Exposure Receptors and Estimation
Human
Receptors
¦Exposures are assessed for two types of farm
residents: young children (age 1-2 years old)
and adults.
Moderate
Overestimate
¦ In the event of a radiological emergency that causes
contamination throughout the site, residents might be
prohibited from or might voluntarily avoid living on-
site.
Exposure
Factors
¦Exposure factors (e.g.,ingestion rates, body
weights) are mean values from USEPA's
(2011) Exposure Factors Handbook and
related guidance.
Neutral
¦Means are used so that exposure is not over- or under-
estimated by this aspect of the approach.
Abbreviations: DAF = dilution attenuation factor(s). Full references are found at the end of the report.
Table 31. Uncertainty in Parameter Value(s) Selected
Parameter
Description
Uncertainty
Rationale for Uncertainty Categoiy
Radiological Emergency Scenario
Radionuclides
Included
¦Radionuclides included in the assessment were identified
from food monitoring following the Fukushima accident.
Moderate
¦The assessment does not include several
other radionuclides that could be released
by the potential emergency scenarios
discussed in Section 2.
¦The radionuclides include ones with short
(8 day) and long (30 year) half-lives.
Releases and Release Rates
Releases
Estimates
¦Each exposure pathway in the assessment begins with a
release of radioactive leachate from a carcass management
unit. Data to characterize amount and rate of leaching
from leachate released following death is uncertain and
very limited.
High
¦Although release estimates were based on
the best available information, releases
might be over or underestimated. In
addition, actual releases can vary
significantly due to many factors (e.g.,unit
design, environmental conditions).
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Parameter
Description
Uncertainty
Rationale for Uncertainty Categoiy
Radioactive
Decay in Soil and
Groundwater
¦Radioactivity concentrations in well water account for
radioactive decay during travel from the source to the
well. The assumed duration is 90 days. This assumption
has a low impact on estimates for radionuclides with long
half-lives (e.g., in years).
Moderate
¦The effect of this assumption on well water
concentrations was evaluated for a series of
durations from 0 to 365 days as shown in
Table 13.
Radionuclide
Partitioning and
Mobility
¦Data on radionuclide leaching from livestock carcasses is
not available. The assessment assumes that radionuclides
are leached in proportion to decomposition fluids released
over the first two months after death as estimated by
Young etal. (2001). This approach does not account for
radionuclide-specific partitioning in tissue compartments
and the associated effect on mobility.
Moderate
¦As discussed in Section 3.1, cesium
radioisotopes distribute throughout the
carcass, while strontium partitions
preferentially to skeletal tissue and iodine
partitions to extracellular fluid. This
leaching is likely to be overestimated for
90 Sr.
Fate and Transport Modeling
Models
¦The assessment uses utilizes two models previously
developed by USEPA: the PRGCalculator and an analysis
using the EPACMTP leaching model.
Moderate
¦The uncertainties associated with the
existing models, data, and methods can
individually contribute to under-or over-
estimation of exposures.
Abbreviations: EPACMTP = EPA Composite Model for Leachate Migration with Transformation Products; PRG = Preliminary Remediation Goals for
Radionuclides
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Table 32. Simplifying Assumptions—Effects on Exposure Estimates
Key Topic
Simplifying Assumption
Effect
Rationale for Effect
Radiological Emergency Scenario
Type of Livestock
Affected
¦The assessment scenario includes management of
cattle carcass. Livestock species differ somewhat in
terms of body composition (e.g., percent fat vs.
muscle; feathers vs. fur), which can affect the rate of
and amount of leaching.
Moderate Over-
or
Underestimate
¦Although cattle are larger than most other
livestock species, smaller animals (e.g.,
poultry) can die in large numbers resulting in
a comparable mass of carcasses to manage.
Body composition varies among species, but
variability is limited by the general similarity
in warm-blooded vertebrate bodies.
Effect of the
Radiological
Emergency on
Management
Activities
¦ Some radiological emergency scenarios include
personal injuries, property damage, or
environmental contamination. This assessment
assumes that the radiological emergency does not
impede, preclude, or otherwise affect any of the
carcass management options. In reality, a
radiological emergency might hinder access to the
site or work in the affected area.
Moderate
Underestimate
¦A disruptive radiological emergency (e.g.,
nuclear power plant accident) might
underestimate exposure if the effects of the
emergency interfere with timely and
effective carcass management.
Site Setting and Environmental Conditions
Site Layout
¦A goal of this assessment is designed to assess
exposure for reasonably anticipated exposure
pathways from carcass management. Therefore, the
conceptual models and site layout were intentionally
designed to include all feasible complete exposure
pathways. For example, residents are assumed to eat
home-grown foods from the radiological emergency
site.
High
Overestimate
¦The assessment is likely to overestimate
exposure because the scenario assumes a
worst-case exposure for each possible
pathway, which is unlikely in the event of a
radiological emergency.
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Carcass Management Options
Design of On-
site
Management
Units
¦Basic assumptions about the design of on-site
management options (e.g., burial trench dimensions) are
based USD A guidance and other relevant sources and an
assumed 50 short tons of carcasses. For larger
mortalities, the spatial pattern and nature of
environmental releases could be different.
Moderate Over-
or Underestimates
¦Assumptions about many aspects of
carcass management units could lead to
over- or underestimation of exposure.
Composting
Duration
¦The compost is assumed to be finished in 8 months. The
duration, along with radionuclide half-lives, affects the
amount of radioactivity remaining in the finished
compost
Low Over- or
Underestimate
¦The assumed duration is based estimates
from the literature. This uncertainty has
the greatest effect for radionuclides with
short half-lives (e.g., on the order of
months or less).
Carcass
Handling Before
Management
¦Workers who handle contaminated livestock carcasses
are assumed to use recommended personal protective
equipment (PPE).
Moderate
Underestimate
¦Exposure to workers is underestimated
if protective equipment is inadequate.
Temporary
Storage
¦In an actual emergency, circumstances might require
temporary storage (e.g., piling) of carcasses until
management options are readied.
¦This assessment does not include temporary carcass
storage.
Moderate Under-
or Overestimates
¦Exposures might be underestimated if
carcass management is delayed,
especially long enough for the carcasses
to begin to release liquid from
decomposition.
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Carcass
Transportation
¦ Based on a semi-quantitative assessment (USEP A
2017a), releases associated with carcass
transportation are assumed to be insignificant and
are not included in this assessment.
Low
Underestimate
¦If carcass transportation results in a significant
exposure, the assessment underestimates
overall exposure.
¦Transportation-related exposures could occur
with any of the management options but have a
slightly greater likelihood with off-site
management options.
Compost
Application
¦The assessment assumes that finished compost is
tilled into soil on site at an application rate based
on an assumed nutrient content.
Low Over- or
Underestimate
¦Radionuclide activity concentrations may be
over- or underestimated depending on the
actual application rate (e.g., kg compost per
acre) and tillage depth.
¦The assessment assumes that finished compost is
tilled into soil on-site and the compost application
site is used to for home grown food production.
High
Overestimate
¦Depending on the radioactivity of the finished
compost, it might be unsuitable for food
production.
Exposure Receptors and Estimation
Homegrown
farm Products
¦Farm residents are assumed to consume only
home-grown fruits, vegetables, and livestock
products.
Moderate
Overestimate
¦Exposure from home-grown foods is estimated
using EPA methods and assumptions;
however, most farm residents also rely on
store-bought foods.
Abbreviations: PPE = personal protective equipment.
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5, Quality Assurance
This report used scientific information extracted from sources of secondary data including
journal articles, publications in the open literature, and government reports both published and
non-published, including distribution limited reports. Data and information were gathered from
published reports to identify the significant pathways by which pathogens might reach
individuals and estimate how many microorganisms an individual is likely to be exposed to
through each pathway. A targeted literature review was performed to identify the most highly
relevant data to inform an exposure assessment. Scientific and technical information from
various sources were evaluated using the assessment factors below:
Focus: The work not only addresses the area of inquiry under consideration, but also
contributes to its understanding. The source is germane to the issue at hand.
Verity: The data are consistent with accepted knowledge in the field, or if not, the new or
varying data are explained within the work. The data fit within the context of the literature
and are intellectually honest and authentic.
Integrity: The data are structurally sound and present a cohesive story. The design or
research rationale is logical and appropriate.
Rigor: The work is important, meaningful, and non-trivial relative to the field. It exhibits
sufficient depth of intellect rather than superficial or simplistic reasoning.
Soundness: The scientific and technical procedures, measures, methods, or models
employed to generate the information are reasonable for, and consistent with, the intended
application.
Applicability and Utility: The information is relevant for the intended use.
Clarity and Completeness: The clarity and completeness with which the data,
assumptions, methods, QA, and analyses employed to generate the information are
documented.
Uncertainty and Variability: The variability and uncertainty (quantitative and qualitative)
related to results, procedures, measures, methods, or models are evaluated and characterized.
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2016. Retrieved June 26, 2017, from: https://www.nrc.gov/waste/llw-
disposal/licensing/locations.html
USNRC. (2014). Backgrounder on Dirty Bombs. Retrieved October 16, 2016, from
http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/fs-dirty-boinbs.htinl
52
-------
WHO. (2018). Management of Radioactivity in Drinking-water. Geneva: World Health
Organization; 2018. License: CC BY-NC-SA3.0 IGO.
WNA (World Nuclear Association). (2017). Nuclear Power in the USA. World Nuclear
Association. Updated June 14, 2017, Retrieved June 27, 2017, from: http//www, world-
nuclear. or»/inforinatio n-library/country-pro files/countries-t-z/usa-nuclear-power, asp x
WNA. (2016). Chernobyl Accident 1986. Nuclear Radiation and Health Effects. World Nuclear
Association. Updated July. Available at: http //www, wo rid- nuc lear. o r g/i nfor matio n-
library/safetv-and-securitv/safetv-of-plants/chernobyl-accident.aspx
Young CP, Marsland PA, and Smith JWN. (2001). Foot and Mouth Disease Epidemic. Disposal
of culled stock by burial: Guidance and reference data for the protection of controlled waters.
Draft R&D Technical Report: Version 7.
53
-------
Appendix A: Conceptual Models
Conceptual Models Outline
This section provides various conceptual models for
each of the management options and related activities
Following sub-sections in Appendix A provide the development and clarifications of
conceptual models for livestock carcass management options:
A.l. Legend to Module Diagrams
A.2. Conceptual Model Overviews
Figures A.l to A. 10
A3. Carcass Management Source Modules
Figures A. 11 to A. 17
A.3.1. Abiotic Compartment Modules
Figures A. 18 to A.21
A3.2. Biotic Compartment Modules
Figures A.22 to A.26
A-l
-------
A.l. Legend to Module Diagrams
Boxes with rounded comers are for Abiotic Environmental Media (e.g., air, surface soil, Groundwater)
Square-corner boxes within an Environmental Medium depict an environmental "phase" (e.g., vapor,
solid/particulate, aqueous) within the Environmental Medium and are color coded (white or "clear"
for gases, light orange for soil and sediment particles, and light blue for ground and surface water).
; Square-corner boxes with a dashed outline indicates the dominant phase for the Environmental
J Medium (e.g., water or aqueous phase is the dominant phase in the surface water column whereas
I
I solids/particles are the dominant phase in sediments, with pore water occupying less volume).
Blue italic labels indicate the transport/transfer process associated with an arrow from one
medium/phase to another, with the width of the arrow suggesting the relative magnitude of the
process > ^
Black dashed arrows indicate vapor phase chemicals, blue arrows indicate
water vapor, and orange arrows indicate particulate phase agents
Open arrow indicates human transport processes
r i
Connections to other Environmental Medium modules are indicated in this type of box.
f
Boxes like this are soil or sediment
compartments
Boxes like this are surface water
L compartments
A-2
-------
A.l. Legend to Module Diagrams (Continued)
Green ovals represent plants, including crops, forage for livestock,
and wildlife, and other plants
Tan ovals represent animals, i.e., humans, livestock, and wildlife.
Some types are receptors of concern whereas others are part of a
food chain leading to receptors of concern
Source boxes with gradient shading represent materials placed at carcass management site to
implement the actions
Red boxes represent carcass and waste management facilities, processes, or supporting
equipment
Blue boxes with gradient shading represent treatment residuals or waste streams
A-3
-------
A.l. Legend to Modu igrams (Continued)
Abbreviations Used in the Figures
CAA
Clean Air Act
CWA
Clean Water Act
MBM
meat and bone meal
NPDES
National Pollutant Discharge Elimination System
PM2.5
atmospheric particulate matter that have a diameter of less than 2.5 micrometers
PM10
atmospheric particulate matter that have a diameter of less than 10 micrometers
RCRA
Resource Conservation and Recovery Act
A-4
-------
A.2. Conceptual Model Overviews
Livestock Carcass Management Option
Figure
On-site Open Burning (pyre)
A.l
On-site Air-curtain Burning
A.2
Off-site Fixed-facility Incineration
A.3
On-site Unlined Burial
A.4
On-site Composting
A.5
Off-site Lined Landfill
A.6
Rendering
A.7
Temporary Carcass Storage
A.8
Carcass Handling
A.9
Carcass Transportation
A. 10
A-5
-------
r ~
Mortalities
On-site Transportation
Combustion
Open Burning
Burial of ash
in place
Air
Particle
Deposition,
Stomatal Uptake
Terrestrial
Plants
Root uptake
Inhalation
Wet & Dry Particle
Deposition;
Diffusive Vapor
Exchange
Wet & Dry
Deposition
Erosion
& Runoff
Ingestion
Livestock
Incidental
Ingestion
Ingestion
Leaching
Uptake,
bioaccumulation
Surface Water
Recharge
Groundwater
Sedimentation,
Resuspension, &
Diffusive Exchange
Aquatic
Life
Ingestion &
Inhalation
Water
Uptake,
bioaccumulation
Ingestion
lon ( Humans )
Ingestion
Inhalation
Figure A. 1. On-site open burning.
A-6
-------
Mortalities
On-site Transportation
Combustion
a:~ D..v»;»n
Burial of ash
in place
Wet & Dry Particle
Deposition;
Diffusive Vapor
Exchange
Wet & Dry
Deposition
Particle
Deposition,
Stomatal Uptake
Erosion
& Runoff
Terrestrial
Plants
Root uptake
Uptake;
bioaccumulation
Aquatic
Life
Leaching
Sedimentation,
Resuspension, &
Diffusive Exchange
Surface Water
Recharge
Inha ation
Uptake;
bioaccumulation
Incidental
Ingestion
Groundwater
Ingestion
Livestock
Ingestion
Water
Ingestion &
Inhalation
Ingestion / \ Ingestion
Humans
Inha ation
Figure A.2. On-site air-curtain burning.
A-7
-------
Off-site Transportation
CAA Permitted Emissions
Ash Disposal
Wastewater Disposal
Wet & Dry
Particle
Deposition;
Diffusive Vapor
Exchange
Wet & Dry
Deposition
CWA Permitted
Effluent Discharge
Particle Deposition,
Stomatal Uptake
Erosion &
Runoff
Terrestrial
Plants
Root uptake
Uptake,
bioaccumulation
Aquatic
Life
Sedimentation,
Resuspension, &
Diffusive Exchange
Inhalation
Uptake,
bioaccumulation
Incidental
Ingestion
Ingestion
Livestock
ingestion
Ingestion
Humans
Inhalation
Air
Sediment
RCRA Subtitle D
Landfill
Mortalities
Off-site
Incineration
On-site Treatment
System
Figure A.3. Off-site incineration.
A-8
-------
Mortalities
On-site Transportation
Diffusion through cover soil
Air
Stomatal Uptake
Terrestrial
Plants
Ingestion
Inhalation
Livestock
On-site Burial
Leaching from to
subsurface soil and
Groundwater
Subsurface Soil
Leaching
Surface Water
Recharge
Groundwater
Ingestion
Inhalation
Ingestion
Ingestion &
Inhalation
Water
Humans
Ingestion
Uptake,
bioaccumulation
Sedimentation,
Resuspension, &
Diffusive Exchange
Aquatic
Life
Uptake,
bioaccumulation
Figure A.4. On-site unlined burial.
A-9
-------
Mortalities
Diffusion from Compost
Windrows
On-site Transportation
Composting
Air
Stomatai
Uptake
Terrestrial
Plants
Root uptake
Inhalation
Ingestion
Livestock
Leaching from
Compost Windrows
&
Application of Finished
Compostto Soil
Incidental
Ingestion
Ingestion
Erosion & Runoff
Leaching Surface Water
Recharge
Groundwater
Ingestion &
Inhalation
Ingestion
Humans
Ingestion
Uptake,
bioaccumulation
Sedimentation,
Resuspension, &
Diffusive Exchange
_~ Uptake,
bioaccumulation
Aquatic
Life
Water
Inhalation
Figure A.5. On-site composting.
A-10
-------
Mortalities
Off-site Transportation
Recovered Methane
Co-located Fuel
Use
L
CAA Permitted Release
Off-site Landfill
Fugitive Gases
(€02, Methane)
Recovered Leachate
Air
Stomatal Uptake
Terrestrial
Plants
Ingestion
Inhalation
Livestock
On-site Treatment
System
CWA Permitted
Effluent Discharge
Off-site River
Inhalation
Ingestion
Humans
Figure A.6. Off-site landfilling.
A-ll
-------
~
Mortalities
Off-site Transportation
CAA Permitted Emissions
Rendering
Unusable Solid Byproducts
RCRA Subtitle D
Landfill
Air
Stomatal
Uptake
Terrestrial
Plants
Inhalation
Wastewater
\ On-site Treatment
Effluent Discharge
Off-site River
[ System
Animal feed
Ingestion
Ingestion
Livestock
Ingestion
Humans
Inhalation
J
Figure A.7. Rendering.
A-12
-------
Mortalities
Particles andVapors
Air
Stomatal
Uptake
Terrestria
I Plants
Leakagetosoil
Leaching and
Sorption to
Subsurface Soil
Surface Water
Recharge
Uptake,
bioaccumulation
Inhalation
Ingestion
Livestock
Ingestion
Ingestion
&
Inhalation
Water
Ingestion
Ingestion
Humans
Inha ation
Sedimentation,
Resuspension, &
Diffusive Exchange
Aquatic
Life
Uptake,
bioaccumulation
Figure A.8. Temporary carcass storage pile.
A4I
-------
Particles andvapors
Incidental
Ingestion;
Dermal
Inhalation
Humans
Air
Carcass
Handling
Mortalities
Figure A.9. Carcass handling.
A-14
-------
Mortalities
J
Particles and vapors
Air
Stomatal
Uptake
Terrestrial
Plants
Ingestion
Inhalation
Livestock
Transportation
<—
Ingestion
Ingestion
Routine Leakage,
Accidental Cargo
Spillage
Incidental
Ingestion;
Dermal
Humans
Inhalation
Figure A. 10. Carcass transportation.
A-15
-------
A.3. Carcass Management Source Modules
Livestock Carcass Management Option
Figure
On-site Open Burning (pyre)
A.11
On-site Air-curtain Burning
A.12
Off-site Fixed-facility Incineration
A.13
On-site Unlined Burial
A. 14
On-site Composting
A.15
Off-site Lined Landfill
A.16
Rendering
A.17
A-16
-------
Combustion
Open Pyre
Residual
Air ! Vapor Phase Chemicals
. (e g., CO;)
Water Vapor (H20)
Smaller Particles (e.g., PM 2.5)
Wind
Larger Particles (e.g., PM 10)
Wet and dry
deposition
I/Vet deposition
Burial of ash in place
To Soil Module
Downwind to Soil and Surface Water Modules
Figure A. 11. Combustion-based management: On-site open burning module.
A-17
-------
Diesel Engine
Combustion
Air Curtain
Residual
Vapor Phase Chemicals (e.g., CO?)
Water Vapor (H20)
Smaller Particles (e.g., PM 2.5)
Larger Particles (e.g., PM 10)
Burial of ash in place
Wef and dry
deposition
->i
Wind
Wet deposition
V
To Soil Module
Downwind to Soil and Surface Water Modules
Figure A.12. Combustion-based management: Air-curtain burning module.
A-18
-------
Incinerator
Residual
Ash
Residual ash
Transport
Air
Vapor Phase Chemicals (e.g., C02)
Air
Pollution
Control
Waste-
water
H
CM
Permitted
Emissions
>
Water Vapor (H20)
Smaller Particles (e.g., PM 2.5)
Wet and dry
deposition
Wet deposition
To Landfill Module
NPDES
permitted
discharge to
surface water
Downwind to Soil and Surface Water Modules
Figure A. 13. Combustion-based management: Fixed-facility incineration module.
A-19
-------
Air
Methane, CO?, and other gases
Precipitation
Surface Soil
T Infiltration
Buried Carcasses
I
Leaching
I
Air spaces
Methane
Advection: dissolved
chemicals
Leaching
5
Leaching
s"
Subsurface Soil
Interstitial
>
Large
spaces
pores
V
J
Chemical & microbe
sorption/desorption
I
Advection: particles
with water
To Groundwater (Aquifer) Module
Figure A. 14. Land-based management: On-site burial module.
A-20
-------
Air
Volatile
i
l
chemicals
£—
NH.
¦ i
i
,
Water vapor
s!
CO,
Compost Covering (wood chips)
Decomposing Carcasses
aerobic decompositiongenerates heat, deactivates microbes)
Compost Underlayer (wood chips)
Leaching
Leaching
*
Leaching
f
\
Soil
Interstitial
Large
spaces
pores
V
J
Advection: dissolved
} chemicals
Chemical & microbe
sorption/desorption
V
Advection: particles
with water
To Groundwater (Aquifer) Module
To Soil Module
On-site Use of
Finished Compost
Figure A. 15. Land-based management: Composting module.
A-21
-------
Downwind to Air
Module
Air
¦ ">
Wind
C02l water vapor (H20)
Co-located Facility
Other vapor-phase
chemicalsfe.g,, methane)
Permitted
air
releases
Water droplets
Fugitive off-
Precipitation
gassing
Landfill
Methane
collection,
Leaching
Wastewater
treatment plant
To Surface
Water Module
mpermeable Liner
Leachate
collection
and
recycling
Decomposing carcasses
Gas
recapture,
burning as
fuel
Figure A. 16. Land-based management: Off-site landfill module.
A-22
-------
Rendering Facility
Air Pollution Control
To Air Module
f 1
Carcasses
(raw material)
To non-
ruminant
animal feed
To Offsite
Landfill
Module
Size .
Reduction
(crushing)
Grinding &
Screening
m
Heat
Processing
Protein &
Bones
Meat and Bone Meal
(MBM) Storage
I
Capture/
condense
Steam
Press
Wastewater
treatment plant
Fat
Cleanup
7
To Surface Water
Module
Fats to
manufacturing
uses of tallow,
etc. and for use
in animal feed
Adapted from Meeker & Hamilton 2006 and from Bisplinghoff 2006
Figure A. 17. Rendering module.
A-23
-------
A.3.1. Abiotic Compartment Modules
Livestock Carcass Management Option
Figure
Air
A. 18
Soil
A. 19
Surface Water and Sediment
A.20
Groundwater
A.21
A-24
-------
Release
during
burn
Long-
term
Releases
Air
Particulates
Dry
Deposition
Sorption
Vapor-phase (gases)
—•>
Sorption
Water [e.g., rain droplets)
Wef
Deposition
Stoma ta I
uptake
Advection
r
To downwind
air;
concentration
decreasing with
increasing
distance from
source
L
J
(i.e., wind)
- ->
Inhalati "" Humans,
Livestock, and
Wildlife
To surface soils, plant
surfaces, and surface water
bodies (sediments)
Plants
(a) Diffusive exchange of gases between air and surface soils
and between air and surface waters are not represented
here because net transfer of diffusive vapor-phase
chemical is relatively minor.
(b) Water as a phase in air (i.e., precipitation) is sporadic.
Figure A.18. Air module3.
A-25
-------
Wet
Deposition
Wet & Dry
Water Deposition
Runoff
Diffusive
Exchanges
Water
Runoff
Particle
Erosion
Surface Soil Interstitial
Space
Pores
Leaching
Particle
Erosion
Subsurface Soil
Particles
Sorption/
Desorption
Leaching
Leaching
Water (i.e., precipitation)!>1
From
source or
from up-
gradient
surface
soils
To adjacent
surface
water
bodies or
more down-
gradient
surface soils
Air
Vapor-phase (gases)
To Groundwater (Aquifer) Module
(a) Precipitation is sporadic and can take different forms with different vapor (and particulate) scavenging efficiencies
Figure A.19. Soil module®.
A-26
-------
Wet
Deposition
(i.e., precipitation
scavenging vapors)
Wet & dry
deposition
Diffusive Exchanges
Runoff
Water Column
Water (i.e., aqueous-phase) |
Erosion
Diffusive
Exchanges
Surface
Water
Recharge
Sedimentation
Particles
Pore
Water
Pore
Water
Water (i.e., precipitation)|a)
Sediment Pore Water
Suspended
Particles
Ground
water
Surface
Soils
Air
i Vapor-phase (gases)
Sediments
Sediment
Particles
Diffusive
Exchanges
(a) Precipitation is sporadicand can take different forms with different vapor (and particulate) scavenging efficiencies
Figure A.20. Surface water module3.
A-27
-------
Sorption/
desorption
Subsurface Soils
Particles/
Solids
nterstitial
Spaces
Pores
Pumping
/pulling
water
Leaching
Leaching
Groundwater (Aquifer)
Sorption/
desorption
Surface
water
recharge
Water (i.e., aqueous phase)
Particles/Solids
Well
Water
To Surface Water Module
(aqueous phase)
Surface Soils
To
household
water
system, crop
irrigation,
and/or
livestock
watering
Figure A.21. Groundwater (aquifer) module.
A-28
-------
A.3.2. Biotic Compartment Modules
Livestock Carcass Management Option
Figure
Aquatic Ecosystem
A.22
Terrestrial Plants
A.23
Livestock
A. 24
Terrestrial Wildlife
A. 24
Human Receptors
A.26
A-29
-------
To human
anglers and
piscivorous
(fish-eating)
wildlife
Organic Terrestrial Particles
Water Column
Algae
sunfish)
Zooplankton )
Minnows
Suspended
Particles
* Benthic
Invertebrates
Sediments
Particles, Organic Particles
Capture by terrestrial animals
"Game" Fish
(e.g., pike, lake
trout largemouth
bass)
Diffusive uptake and
excretion of chemicals in
water across animal gills&,
outer algal cell walls.
Capture /
V
N
Bottom
Fish
Compartment Legend:
Algae
Pore Water
J) Invertebrates
Transfer Pathway
Legend:
I Sedimentation of
X dead organisms
S Capture
Ingestion
Figure A.22. Aquatic ecosystem bio tic module.
A-30
-------
Humans
Wildlife
Livestock
Particulates
Well
Water
Dry & Wet Deposition1
Va
phase Diffusive
(gases) Exchanges
Crops
Surface Soil
Subsurface
Soil
Root Uptake of Soluble Chemicals
High Kow chemicals & microbes
sorbedto soil particles
Vapor-phase chemicals can be absorbed from air and lost H , . 1 „ . <
... , . . . . Irrigation > Particle deposition I /
to air by plants when leaf stomata are open during the ^ v I
day.
Figure A.23. Terrestrial plants module.
A-31
-------
Inhalation
Poultry
Cattle
(grazers)
A
Ingestion
(feed)
A
MBM
added
Swine
Ingestion
(forage
plants)
Ingestion
(drinking
Water)
feed
Incidental
Soil
ingestion
Ingestion (plant
materials)
Dairy
Feed
Water
troughs
Feed
Rendering
Module
Groundwater
Module
Air
Vapor-phase (gases)
Particulates
Terrestrial Plant
and Soils Modules
Figure A.24. Livestock module.
A-32
-------
Inhalation
Ingestion
(forage)
Terrestrial
Plants
Module
Herbivorous
Wildlife
Piscivorous
Wildlife
Ingestion
(drinking
Water)
Surface Water
Biotic Module
Bottom Fish
Capture and
ingestion by
piscivorous (fish-
eating) wildlife
"Pan" fish
(e.g.,
iunfijh)
Figure A.25. Terrestrial wildlife module.
A-33
-------
f
\
Surface Soil
Module
v
Well Water
(Groundwater
Module)
Fish {Surface /
Water Biotic
Module)
Ingestion
Poultry
(Livestock
Module)
Humans
Ingestion
Cattle
(Livestock
Module)
Incidental
Soil ingestion
Ingestion (drinking
water, cooking
water, e.g., in rice)
Dermal/Inhalation
—?[ (Bathing)
ingestion
of Crop
Plants
Terrestrial
Plants
Module
Home Water
( , ^
Air Particulates
Inhalation
1 Vapor-phase (gases) i
L J
Incidental ingestion (during
recreation/ swimming)
f "N
Surface Water
Module
^ j
Sediments
Ingestion of
Feed and
Forage
Figure A.26. Human receptor module.
A-34
-------
appendix L\ Jditiorr .1 I' «ionuclide Exposure Information
-------
R„1 Important Radioisotopes and Their Half-lives
Every chemical element has one or more radioactive isotopes that differ by the number of
neutrons in the atom's nucleus. Chemical elements have a different number of protons, ranging
from 1 for hydrogen to 93-103 and higher for the transuranium elements (i.e., elements with
atomic numbers—that is the number of protons—higher than uranium). Hydrogen (H) has three
isotopes with masses of 1, 2, and 3 grams/mole (g/mol). Only 3H (tritium), with 1 proton and 2
neutrons, however, is radioactive; the other two isotopes are stable and do not emit ionizing
radiation. Isotopes are identified by their atomic mass (e.g., 210Pohas 84 protons and 126
neutrons, for a total atomic mass of 210 g/mol).
Only approximately 50 of the more than 1,000 known radioactive isotopes of various elements
occur naturally in the environment. Those include radioactive isotopes of uranium and thorium
and 40K. Isotope decay products (daughters) of uranium and thorium include isotopes of
polonium, radium, and radon. Most currently known radioactive elements have been produced
artificially in nuclear reactors. For example, all of the transuranium elements (e.g., plutonium,
americium, curium, berkelium, californium) were first created and isolated in nuclear
laboratories starting in the 1940s.
Groups of radioisotopes associated with uranium mining, fueling nuclear power plants, produced
in reactor cores and nuclear bomb detonations, are presented in Tables B.l.l through B.1.3,
respectively.
B-2
-------
Table B.1.1. Uranium-238 Decay Series (Uranium Mines)
Element
Isotope
Emits
Half-life
Comment
U
Uranium
a
4.5 billion
years
Parent isotope - most abundant
Th
Thorium
234
P,Y
24.5 days
No change in atomic number or weight; short
half-lives
Pa
Protactinium
234
P,Y
1.14 minutes
U
Uranium
234
a
233,000
years
Each alpha (a) particle emission (loss of 2
protons and 2 neutrons) reduces the atomic
Th
Thorium
230
a
83,000 years
number by 2 and the atomic weight (isotope
number) by 4
Ra
Radium
226
a
1,590 years
Rn
Radon
222
a
3.83 days
Po
Polonium
218
a
3.05 minutes
Pb
Lead
214
P,Y
26.8 minutes
No change in atomic number or weight; short
half-lives
Bi
Bismuth
214
P,Y
19.7 minutes
Po
Polonium
214
a
15
milliseconds
Very short half-life
Pb
Lead
210
P,Y
22 years
No change in atomic number or weight
Bi
Bismuth
210
P,Y
5 days
Po
Polonium
210
a
140 days
Final alpha decay leads to stable Pb
Pb
Lead
206
stable
stable
No further decay; not radioactive
Symbols: a = alpha particle; p = beta particle; y = gamma radiation.
Uranium is a naturally occurring radioactive element with no stable isotopes. In the United
States, between 1953 and 1980, uranium was mined primarily in Arizona, Colorado, New
Mexico, South Dakota, Texas, Utah, Wyoming, and Washington. Table B.l.l shows the series of
elements and isotopes produced by natural 238U decay, ending with 206Pb, which is stable. Note
that the longer the half-life, the more "stable" the isotope. 238Uis the most stable and most
abundant isotope (99.2739-99.2752% of total uranium) with a half-life close to the age of Earth.
The radioisotopes found in uranium mines are predominantly those that result from the natural
decay of 238U, as shown in Table B.l.l.
Table B. 1.2 lists several isotopes of uranium, plutonium, and thorium, some of which are natural
and some of which are created in nuclear facilities. Although some other radioisotopes can be
used in nuclear power plant (NPP) fuels, uranium and plutonium are the primary elements used.
235U, which is fissile (i.e., can support nuclear chain reactions in NPP reactors), is only 0.7% of
natural uranium.
B-3
-------
Table B.1.2. Some Isotopes of Uranium, Plutonium, and Thorium
Element
Iso-
tope
Emits
Half-life
Comment
232
a
69 years
Has been produced in breeder reactors.
234
a
248,000 years
Product of 238U decay.
U
Uranium
235
a
713 million
years
0.7% of naturally occurring uranium; highly
fissile, mined and enriched to produce NPP fuel
238
a
4.5 billion years
Primary natural form of uranium; not fissile;
breeder reactors transmutate 238U to fissile 239Pu
238
a
87.7 years
Not fissile; decays to 234U; can release fast
neutrons
Pu
Plutonium
239
a
24,110 years
Primary fissile isotope used in NPPs and in
bombs
240
a
6,563 years
Spontaneous fission to 236U
241
P
14.4 years
Fissile; decays to241 Am
244
a
80 million years
Found in trace quantities on earth
Th
Thorium
232
a
14 billion years
Occurs naturally, longest half-life of
significantly radioactive isotopes; decay series
ends in stable lead; can be transmuted to 235U in
breeder reactors
230
a
83,000 years
Produced in the decay chain of 238U
Symbols: a = alpha particle;
3 = beta particle; y = gamma radiation. NPP = nuclear power plant
Considering the uranium (U) isotopes listed in Table B.1.2 above, before use in NPP fuel rods,
the proportion of uranium that is 235Umust be enriched from 0.7% to between 3.5% and 5.0%
(USNRC 2014). 232Uis not naturally occurring but has been produced in fission reactors. 234Uis
the decay product of 238U after an alpha particle has been released. As noted in Table B.1.2
above, 238Uis the most abundant isotope of uranium, but it is not fissile.
Plutonium (Pu) is a transuranic element with atomic number 94. Scientists at the University of
California at Berkeley first produced and isolated 238Puin 1940. Breeder reactors can transmutate
238Uinto fissile 239Pu. In a breeder reactor, neutrons with kinetic energy above 1 MeV enter the
nuclei of 23 8U atoms creating 23 9Pu. Fission of 23 9Pu produces up to one third of the power
generated by a breeder reactor. Recovered from fiiel recycling processes, 239Puis the primary
fissile isotope in use in NPPsand in nuclear weapons (Table B.1.2). 240Puis the main impurity in
recovered 239Pu. Because 240Pu exhibits a high rate of spontaneous fission, the "grade" of239Puis
listed by its 240Pu content: weapons grade has less than 7%, fuel-grade has 7-19%, and NPP-
grade can contain 19% or more 240Pu. For weapons carried on submarines, less than 4% 240Puis
allowed.
232Th accounts for virtually all of the naturally occurring thorium. Its half-life is more than three
times the age of Earth. A few thorium-based nuclear reactors have been built; more are expected.
In a breeder reactor, 232Th can be transmuted into 235U for use in conventional NPPs.
B-4
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Table B.1.3 lists some additional radioisotopes that might be released to the environment from
one or more types of possible radiological incidents. For NPPs, fission product inventories are
proportional to the long-term thermal power of the NPP. In 1988, the U.S. Nuclear Regulatory
Commission (USNRC) estimated the inventory of fission products in NPPs (in active or spent
fuel rods) at the time, in units ofCi/MWe (Curies per megawatt-electrical). Those estimates are
in the "Inventory" column of Table B.1.3 (USNRC 1988, Table 2.2). The first group, iodine
isotopes from 131 to 135, has short half-lives compared with the elements and isotopes that
follow. 1311 is the iodine isotope of most concern because of its relatively longer half-life of 8
days. Radioisotopes with half-lives less than several minutes are not included in Table B.1.3.
Additional relatively well-known radioisotopes are listed with "NA" for the inventory column
(i.e., not included in the USNRC 1988 list) in Table B.l.l. Some are synthesized in nuclear
reactors for medical and other applications. Others occur naturally and are useful in radio-dating
materials on earth.
JB.2, Measuring Radiation Emissions arid Exposures
Measures of radiation are complex because some radiation is pure energy (e.g., gamma and X-
rays) while other types of radiation (alpha and beta) include both particles and energy. Some
measures apply to emissions from a material and can be measured at a meter or so from the
source. Other metrics indicate absorbed doses, and still other metrics reflect the relative damage
produced in humans, which depends on the type of radiation as well as its energy levels.
B.2,1 Metrics
Table 1 in the main report identifies four metrics used to measure radioactivity and exposure.
Further information on these is provided in Table B.1.3.
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Table B.1.3. Other Radioisotopes Associated with Nuclear Power and Found in the
Environment
Element
Iso-
tope
Emits
Half-life
Inventory
(Ci/MWe)
Comment
Fission products in U-235 nuclear reactors
131
P,y
8.0 days
85,000
NPP fission product
132
P,y
2.3 hours
120,000
I
Iodine
133
P,y
20.8
hours
170,000
Other iodine radioisotopes released, but of less
134
P,y
42.6
minutes
190,000
concern because of shorterhalf-lives
135
P,y
6.6 hours
150,000
Sr
Strontium
89
P
50.5 days
94,000
NPP fission product; used in treatment of bone
cancer
90
P
29 years
3,700
NPP and weapon fission product; has medical
uses
134
P,y
2.1 years
7,500
NPP fission product; but not produced by
Ce
Cesium
136
P,y
13 days
3,000
nuclear weapons
137
P,y
30 years
4,700
Common NPP fission product of 235U
85
P,y
10.7
years
560
NPP fission product; gas — disperses
Kr
Krypton
87
P,y
1.3 hours
47,000
NPP fission product; gas — disperses
88
P,y
2.8 hours
68,000
NPP fission product; gas — disperses
133
P,y
5.2 days
170,000
NPP fission product; gas — disperses
Xe
Xenon
135
P,y
9.1 hours
34,000
NPP fission product; gas — disperses
138
P,y
14 min
170,000
NPP fission product; gas — disperses
Othe r radiois otopes
Se
Selenium
79
P
327,000
years
NA
In spent nuclear fuel and wastes from fuel
reprocessing
CI
Chlorine
36
P
300,000
years
NA
Non-reactive; suitable for geologic dating;
produced by irradiation of seawater during
nuclear weapons testing between 1952 and 1958
K
Potassium
40
a, P, y
1.25
billion
years
NA
Used in potassium-argon dating; ranks third as a
source of radiogenic heat in the Earth's mantle,
after 232Th and 238U
Co
Cobalt
60
P,y
5.27
years
NA
Artificially produced in nuclear reactors,
relatively long-lived source of high-intensity
gamma rays used in sterilization of medical
equipment and for medical radiotherapy
H
Tritium
3
P
12.3
years
NA
Produced by irradiating lithium metal in a
nuclear reactor, many uses including boosterin a
hydrogen-bomb
Source for Inventory column in Ci/MWe: USNRC 1988, Table 2.2.
Additional acronyms: a = alpha particle emissions; p = betaparticle emissions; y = gamma radiation; Ci/MWe =
Curies per MWe; NA = not applicable (not listed by USNRC 1988); NPP = nuclear power plant; MWe = megawatt-
electrical - size of nuclear core; 235U= fissile uranium
B-6
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¦ Disintegrations per second. Radioactivity of some materials can be measured as
disintegrations per second. Alpha and beta emissions (and some lower energy gamma rays)
can be measured by a Geiger counter by detecting the ionization produced by a radioactive
particle. A typical Geiger counter measures the ionization effect produced in the gas
contained in a Geiger-Miiller tube. The electrons are immediately attracted to a thin wire of
tungsten with a high positive voltage producing an electric pulse. The International
Commission on Radiation Units and Measurements (ICRU) established the Becquerel (Bq)
equal to one disintegration per second. In the United States, measures of radiation started as
Curies (Ci), with one Ci set equal to the particle emissions from one gram of radium in one
second.
¦ Dose-equivalent. Some types of radiation cause more damage than others. Therefore, a
different unit is needed to equalize all ionizing radiations relative to their potential to cause
biological harm. The Sievert (Sv) is defined as the amount of radiation that is roughly
equivalent to the effectiveness of one Gray (or lOORADs) of gamma radiation (see
paragraph below). Because the Sv is quite large for most applications, millisieverts (mSv)
commonly are used. One mSv equals 10 ergs of energy of gamma radiation transferred to
one gram of living tissue.5
¦ Exposure (gamma and X-rays). Gamma (and X-ray) radiation are quantified by units of
ionizing exposure. Using IUs, gamma emissions are reported in Coulombs (C) created per
kg of matter (C/kg).6 That is the quantity of radiation required to create one C of charge of
each polarity (both negative and positive) in one kg of matter. In the United States, the
Roentgen (R), on the other hand, was set to the quantity of radiation required to create one
electrostatic unit (esu) of charge of each polarity in one cubic centimeter of air. Table A.2.1
provides the conversion factors between C/kg and R units of exposure. Low energy gamma
radiation can be measured by a standard Geiger counter; higher energy gamma radiation can
be measured in more sophisticated ionization chamber.
¦ Absorbed dose. The amount of gamma radiation absorbed is reported in units of gray (Gy)
or (less preferred) units of Roentgen Absorbed Dose (RAD). One Gy is defined as one joule
(J) of radiation energy per kg matter. The Gy is independent of biological context. To
estimate the equivalent dose absorbed in a human body, units of Sv are used (see above).
One Gy = 100 RADs. One Gy absorbed dose of alpha particles is equivalent to 20 Sv. One
Gy absorbed dose of gamma radiation equals 1 Sv.
B.2,2 Comparing Metrics
Radiation weighting factors (RWF) can be used to convert the physical dose in Gy to a
biologically equivalent dose in Sv. The International Commission on Radiological Protection
(ICRP) has issued recommendations for human protection, starting in 1991. The RWF is
intended to account for the difference in damage to humans caused by different types of radiation
for equal amounts of radiation energy deposited. Photons and electrons of all energies have an
5 One erg equals 100 nano Joules (nJ), the amount of work done by a force of one dyne exerted for a distance of one centimeter.
One erg also equals 6.24E+11 electron volts (eV).
6 One Coulomb (C) is equivalent to one ampere-second. An electric current of 1 ampere represents 1 C of unit electric charge
carriers flowing past a specific point in 1 sec. The unit electric charge is the amount of charge contained in a single electron.
Thus, 6.24E+18 electrons have 1 C of charge, as would the same number of protons (but with the oppositepolarity).
B-7
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RWF of 1.0 (ICRP 1991, 2007 as cited in ENS 2013). The 1991 ICRP recommendation for
protons with energy of more than 2 MeV was a RWF of 5 and for protons with lower energies, it
was 2. However, the ICRP 2007 recommendation for protons is an RWF of 2 (ENS 2013).
For neutrons, the RWF is a function of neutron energy (e.g., see Figure 4-1 in LaPlante et al.
2011). The continuous distribution can be broken down into categories. For neutrons with
energies:
<10 keV RWF =5
10 keV to 100 keV RWF = 10
>100 keV up to 2 MeV RWF =20
>2 MeV up to 20 MeV RWF = 10
>20 MeV RWF = 5
Tissue weighting factors (TWF) are used to account for differences in radiation response of
different organs for equal amounts of radiation energy deposited in an organ (LaPlant et al.
2011). We do not list those here, however, because we will not use tissue-specific radiation
limits; whole body radiation limits are used for purposes of this assessment. Table B.2.1
compares biologically equivalent doses of radiation for familiar sources.
Table B.2.1. Radiation Exposures by Sources or Effect Levels
Source
mrem
IU
Reference
Airport screening
0.010
0.1 (iSv
Dennison 2016
Airline crew flying NY to Tokyo Polar Route
5
50 (jSv
WNA 2016
Chest X-ray
10
100 (iSv
Dennison 2016
Natural background (annual)
300
30 mSv
Dennison 2016
Natural background (annual)
620
6.2 mSv
USNRC 2014
CT full body scan
1,000
10 mSv
USNRC 2014
Occupational annual limit
5,000
50 mSv
Dennison 2016
Dose from 4 months on International Space
Station
10,000
100 mSv
WNA 2016
Clinical signs of illness (e.g., temporary
radiation sickness; likely to cause a fatal
cancer years later in 5/100 persons exposed)
100,000
1 Sv
WNA 2016
50% survival (whole body exposure)
400,000
4 Sv
Dennison 2016
100% fatal within a few weeks
1,000,000
10 Sv
WNA 2016
Radiotherapy (at the site of the tumor)
8,000,000
80 Sv
Dennison 2016
Acronyms: IU = international units; (iSv = microsievert; mSv = millisievert; mrem = millirems ormilli (radiation
exposure-man); NRC = Nuclear Regulatory Commission; WNA = World Nuclear Association.
USEPA has published Dose Conversion Factors (DCF) and Derived Response Levels (DRLs) for
a 4-day exposure to gamma radiation from deposited radionuclides for each radioisotope that
might occur (Table 5-5 in USEPA 1992, cited in USEPA 2013).
B-8
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R„3 Emergency Responses to Protect Human He; it! Food Supply
In the event of a radiological emergency, livestock carcass management will be planned and
implemented in the context of a broader response action. This section describes relevant phases
and guidelines in those circumstances.
B.3.1 Response Phases
Under federal supervision, immediate responses to radiological incidents should be designed to
best protect humans from harm. Four phases to ensuring a protective response include: (1)
emergency response planning; (2) early response immediately following a release of radiation
(first hours to days), (3) the intermediate response to protect persons from radiation over the
following weeks and months, and (4) later phases where long-term solutions for cleanup and
"disposal" are evaluated and implemented (USEPA 2013). This section briefly discusses phases
1 to 3 below.
Emergency Planning
Emergency planning is conducted at local, state, and federal levels with many agencies involved.
For large NPPs, for example, state maps delineate both a 10-mile radius for actions to prevent or
limit inhalation exposures and a 50-mile radius for actions to prevent or limit ingestion of
radioactive materials that deposit from fallout as a radioactive plume passes (NJ OEM 2012).
Large NPPs must maintain detailed rapid-response inhalation emergency plans considering the
possibility of an explosion, lire, and or core meltdown, with options for protecting workers and
surrounding populations within the first hours (e.g., notification and sheltering in place) and days
(e.g., evacuation when safe). The plans also prescribe the computer simulation tools and the
types of radiation monitoring that would be used to make decisions over the longer term. For
NPPs or weapons installations near livestock production areas, the plans should include options
for protection of livestock to the extent feasible under the circumstances.
Rapid Early Responses
As illustrated in Figure A.3-l,the dangerous inhalation fallout plume initially expands in size
over a few hours as it travels from the source downwind. As radioactive decay proceeds,
however, the dangerous fallout plume shrinks. Thus, for persons beyond the boundary of
physical damages from an initial blast/fire/thermal wave, sheltering in place often is the best
initial response. At some locations, people might be evacuated before the plume reaches them.
Similarly, if there is time to move livestock to shelters ahead of the arrival of a plume of
dangerous radioactivity, farmers might be so advised. Sheltering in structures not only reduces
inhalation exposure, but it can stop deposition of radioactive isotopes onto humans and animals.
The actual distances and directions that radioactive gases and particles could travel depend
primarily on the prevailing weather conditions (e.g., wind direction and speed, precipitation).
Heavier particles will deposit closer to the source than lighter particles. Strong winds can spread
the gases and lighter particles over a larger area, which would dilute the concentration of
radioactive materials depositing to ground-level. Rain can scavenge gases and particles from the
atmosphere, in what is called wet deposition, and can increase the concentration of radioactive
materials on the ground, with significant local variation in concentrations.
B-9
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After the initial dangerous fallout plumes have passed an area, evacuation might be
recommended, with various areas designated for temporary housing. For livestock, relocation to
"clean" areas, if available, could commence, with washing off the materials deposited to their fur
or feathers and walking them through water decontamination stations. For livestock that cannot
be relocated, provision of clean food and water, with a focus on water, is important.
Feed that has not been stored in the open can be used; foods such as clean hay bales should be
covered by tarps if time permits. After a plume passes, even exposed silo bunkers can be used
after the top exposed layer is removed (NJ OEM 2012). Substantial guidance on early response
actions is available from numerous sources (e.g., USDHHS 2016;USEPA 2013; NJ OEM 2012
and other state guidance; USNRC 2016).
All agencies warn that livestock exposed to the radioactive plume and in a fallout area should not
be slaughtered as an initial response. The possible exposures to humans from handling livestock
with external contamination from fallout are too high. Only later, once radiation levels have
declined, should decisions be made based on monitoring data and local conditions. Moreover,
immediate slaughter requires disposing of the carcasses as biological radioactive waste—several
sources quote $8,000 dollars as the cost of disposing of a single cow at a licensed radioactive
waste disposal site (McMillan etal. 2011, Brandl et al. 2012).
Intermediate-Phase Responses to Airborne Releases
While early response actions are implemented, site-specific projections of the area covered by
the radioactive plume and cumulative fallout are computed based on local meteorological
conditions and what is known about the incident. The ingestion emergency planning zone
generally starts with a 50-mile (80.5 km) radius, but more specific designations are developed as
data on the incident is updated (USEPA 2013).
During the intermediate-phase, radiation monitoring helps to define when and where radiation
from groundshine (deposited fallout) is sufficiently low to allow re-entry by civilian populations.
For short-lived radionuclides like 131I or 134Cs, an area might be considered safe after 10 or fewer
half-lives have passed and measurements confirm radiation levels are less than 2 times
background concentrations. Exposed soils might be tilled underground; some crops could be
composted. Milk products contaminated with 1311 could be frozen, powdered, or canned and
stored until the 1311 radioactivity has declined to levels considered safe. Feed with potassium
iodide added could help to clear inhaled or ingested 1311 from the thyroid gland, where it
concentrates in animal bodies. For longer-lived radionuclides, like 89Sr or 136Cs with half-lives of
50 and 13 days, cleanup options must be evaluated on a site-by-site basis; again, radioactive
decay will likely be sufficient after several months or years to allow reuse of an area. Strontium,
however, bioconcentrates in bones (behaves like calcium); thus, if livestock were not provided
clean feed throughout the response period, their future uses could be compromised. Cesium does
not concentrate in any particular part of the body.
In areas contaminated with even longer-lived radioisotopes, decisions are more difficult, and
cleanups can be very costly. For areas important to human welfare and residences, costs of
cleaning and disposal of radioactive debris are compared with the need for those areas. Livestock
internally contaminated with these isotopes might require slaughter, and options for disposing of
radioactive carcasses would require evaluation.
B-10
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B.3,2, Protective Guidelines
In the event of a radiological emergency, response actions, including carcass management
activities at the site, may follow USEPA's proposed Planning Guidance and Protective Action
Guides (PAGs) for Radiological Incidents. PAGs are exposure levels that should trigger
protective actions in the early and intermediate phases of response following a nuclear incident.
Local, state, and federal agencies can use PAGs to guide decision-making. Agencies also can
recommend protective actions at lower radiation levels or modify responses to ensure the highest
protection for the largest population.
First published in 1992 (USEPA 1992), the PAG Manual was revised and published for Interim
Use and Public Comment in 2013 (USEPA 2013). The interim PAGs are listed in Table B.3.1
below. In the event of a nuclear incident, "early responses" focus on protection from exposures
via all exposure pathways. For "intermediate responses", the dose of interest is the sum of the
effective dose from external exposures and the effective dose from materials inhaled (e.g., prior
to evacuation) (USEPA 2013, Section 3.4.2 on dose projections).
B-ll
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Table B.3.1. USEPA Protective Action Guides (PAGs) for Radiological Incidents
Phase
Action
Action Level (exposure)
Early
responses
(within
hours or
days)
Sheltering-in-place
or evacuation of the
public1
1 to 5 rem (10 mSv to 50 mSv) whole body projected dose over 4
days; beginning at 1 rem, whichever action or combination of
actions results in the lowest exposure for the majority of the
population
Administration of
prophylactic drugs
(KI)2
5 rem (50 mSv) projected child thyroid dosed from radioactive
iodine (based on data from Chernobyl exposure data)
Limit emergency
worker exposure
5 rem (50 mSv) per event and year (all occupational exposures)
10 rem (100 mSv) (protecting valuable property for human
welfare, NPP)
25 rem (250 mSv) (lifesaving or protection of large populations)
Supplementary
administration ofKI
5 rem (50 mSv) projected dose to child thyroid from exposure to
iodine-131
Intermediate
Responses
Relocation of public
for 1 or more years
2 rem (20 mSv) projected dose over first year
Subsequent years, 0.5 rem (5 mSv)/year projected dose
Food interdiction
0.5 rem (5 mSv)/year projected dose, or 5 rem (50 mSv)/yr to any
individual organ or tissue, whichever is limiting
Limit emergency
worker exposure
5 rem (50 mSv)/yr (or greater under exceptional circumstances)
Later
Responses
Workers in
restricted areas
> 2 mrem (20 mSv) /hr or > 100 mrem (1 mSv)/yr should operate
under controlled conditions established for occupational exposures
Source: USEPA 2013, adaptedfrom Tables 1-1, 2-2, and Section 2.7.
Abbreviations: KI = potassiumiodide - not radioactive; hr= hour; mrem = millirem; mSv =millisievert; NPP =
nuclear power plant; rem = radiation exposure-man; yr = year.
1 Projected dose = sum of the effective dose from external radiation exposure (i.e., "groundshine" and "cloudshine")
and the committed effective dose from inhaled radioactive material. Other protective actions would be advisable
independent of a PAG (e.g., face mask to reduce inhalation of particles, decontamination by removing clothing).
In addition, the U.S. Department of Energy's (USDOE) Federal Radiological Monitoring and
Assessment Center (FRMAC) Assessment Manuals (USDOE 2010a, b) provide detailed
guidance for calculating dose projections downwind of an accident. The FRMAC Assessment
Manuals incorporate the International Commission on Radiological Protection (ICRP)
Publication 60 series dosimetry models (ICRP 1991). In addition, the Federal Radiological
Preparedness Coordination Committee (FRPCC) encourages use of computational tools (e.g.,
USDOE's Turbo FRMAC and USNRC's Radiological Assessment System for Consequence
Analysis or RASCAL as cited in USEPA 2013) to develop incident- and location-specific
projections.
Official decision makers must weigh the risks and benefits of response actions for specific
incidents. One-hundred percent protection of humans is possible if evacuation occurs before an
airborne plume reaches an area. However, evacuation might not be appropriate if associated risks
B-12
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and secondary effects are more severe than the risk of the projected exposure to radiation
(USEPA 2013). Sheltering in place can be both protective and cost-effective if projected doses
over the first four days are less than 1 rem (10 mSv).
In the intermediate phase, persons can be relocated to areas beyond the area contaminated by
fallout (which would continue to emit radiation, called "groundshine"). Depending on the half-
lives of the radioactive materials deposited to the ground, reentry might be allowed in weeks or
months, or authorities might declare an area a permanent exclusion zone (e.g., around
Chernobyl).
Over the longer term, three general "outcomes" are possible. For radioisotopes with short half-
lives (e.g., 13 *1), radioactive emissions can decline to acceptable levels (e.g., no more than 2x
natural radiation at a location) over weeks or months, with no cleanup actions required. For
radioactive materials with longer half-lives distributed over a relatively small area at more than
twice background levels, surface decontamination might be possible (e.g., surface soil scraping),
with the radioactive materials moved to a controlled hazardous materials waste site. Or, if
decontamination is not cost effective, the area deemed contaminated at unacceptable levels can
be declared an exclusion zone for periods of years or "permanently."
R„4, Livestock Exposure and Salvage
Exposure to ionizing radiation occurs in several different ways for livestock, and the important
exposure pathways change overtime. Sections B.4.1 and B.4.2 discuss short-term pathways and
longer-term pathways, respectively. However, for livestock to become unfit for their intended
uses, and to require slaughter, internal contamination is more important than external
contamination, which could be washed off Section B.4.3 describes some options for salvaging
livestock, reducing the number of animals that need to be culled under some conditions.
B.4.1 Livestock Exposure Pathways - Short Term
As described in previous sections, following a radiological incident, both humans and livestock
can be exposed. Three exposure pathways are possible in the short-term (e.g., over the first few
days):
1. External exposure to penetrating radiation—Direct exposure to penetrating gamma
radiation and beta particles from cloudshine or groundshine (assume that fast neutrons occur
at dangerous levels only in cores of reactors; alpha particles cannot penetrate skin). This
type of radiation might affect the health of livestock; however, it would not result in
livestock being radioactive themselves.
2. Inhalation—Direct inhalation of alpha and beta particles and radioisotopes from an
atmospheric plume of contamination and inhalation of deposited radioactive particles that
are re-suspended from ground as dust. Alpha particles would deposit along the respiratory
tract and could damage epithelial cells. The deposited radioisotopes could continue to
decay, emitting alpha, beta, and gamma radiation. Some radioisotopes might be absorbed
into the bloodstream; however, the primary inhalation exposure would last for a few days.
3. Surface contamination—Deposition of radioactive materials to the surfaces of people and
animals and deposition to the ground of materials that emit penetrating gamma rays and
beta particles, irradiating humans and livestock where they stand (groundshine). Surface
B-13
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contamination can be washed off via water sprays and walking livestock through a water
through on their way to a clean area (e.g., see NJ OEM 2012); however, a plan for the
contaminated wash-water is needed.
4. Ingestion—If not supplied with clean feed and water immediately, livestock, particularly
free-range livestock, are likely to start ingesting contaminated feed and possibly water.
Livestock might have to "fend for themselves" for several days before it is safe for farmers
or emergency responders to provision or move them.
B.4,2 Livestock Exposure Pathways - Longer Term
Over the longer term, radioactive materials deposited to surfaces (e.g., buildings, crops,
livestock, soils, surface waters, and any other materials open to the air) can, depending on the
half-life of the radioisotopes, continue to emit radiation over weeks, years, decades, or millennia.
This groundshine can be measured using Geiger counters of appropriate design.
Ingestion of radioactive materials by livestock is the primary concern over the longer term:
• Free-range livestock could ingest large quantities of radioisotopes if allowed to continue
to forage on pasture or fields over which a radioactive plume passed. Grazing livestock
such as beef and dairy cattle, sheep, and goats, would ingest materials deposited to the
forage plant surfaces and also incidentally ingest contaminated surface soils. Chickens
foraging on seeds and insects on the ground could similarly ingest fallout. If not
provisioned or moved from such an area, the animals might become radioactive
themselves.
• If fed grains or hay that was exposed to fallout or if watered with contaminated
groundwater or open-top on-site ponds, large numbers of livestock also could ingest
radioisotopes over longer periods of time
Providing clean feed and water can allow livestock to return to productive uses if they are
contaminated with relatively short-lived isotopes. Salvaging livestock by such measures can limit
or prevent culling animals and needing to manage radioactive carcasses.
B.4,3 Salvaging Livestock
Most livestock outside the zone of physical/thermal damage and intensive initial radiation from a
radiological incident might tolerate the short-term inhalation and ingestion exposures without
becoming ill. Options for saving and decontaminating livestock, which depend on the type of
radioactive materials and their half-lives, depend on cost-effectiveness of managing a herd over
the period of time required for radioactivity to decline to acceptable levels. Slaughter and carcass
management is necessary if the livestock are very sick (unlikely) or if contaminated with
radioactive materials that cannot be cleared from their system (Brandl etal. 2012; Dennison
2016).
Some measures could decontaminate livestock that have ingested radioisotopes over the short-
term (e.g., 2 to 4 days) if circumstances permit (Dennison 2016):
1. Provision of clean food and water, if possible, can help eliminate many isotopes from the
body, and the isotopes with shorter half-lives (e.g., 1311) will decrease in radioactivity over
time.
B-14
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2. Binding agents like bentonite clay or Prussian blue might prevent absorption of radioactive
particles that are ingested immediately following an incident before livestock can be removed
from pasture, for example.
3. Testing livestock for whole body radioactivity is needed to determine when they could be
slaughtered for meat products. If radioisotopes in livestock and have a short half-life, (e.g.,
1311), continuation on clean food and water until sufficient half-lives have passed might be all
that is required. Testing for radioactivity is required to confirm when slaughter for meat
products could be done.
4. Eggs and milk need to be tested. Milk contaminated with 131I can be frozen or powdered or
canned and stored for the few months required for radiation to fall to acceptable levels. Eggs
contaminated with 131I could be powdered.
For animals that have ingested radioisotopes with longer half-lives, animals and products might
not be salvageable. Determining which animals need to be euthanized is a delayed priority.
Measures taken to decontaminate livestock and to reduce their body burdens of radioactive
materials also will reduce the number of carcasses overall and the number that need to be
managed as radioactive waste compared with standard waste. For example, following the
Chernobyl reactor accident, contaminated livestock were slaughtered immediately due to fear
and anticipated economic losses, which complicated the carcass management process and
increased the quantity of radioactive waste materials requiring special disposal (IAEA 2006).
They did not consider the substantial cost associated with radiological waste disposal. Animals
with internal doses below the LDio (lethal dose for 10 percent of the animals) are not expected to
display observable symptoms that would provide grounds for immediate disposal (Brandl et al.
2012).
Recognizing that salvaging livestock requires guidance on what level of contamination would be
acceptable, Brandl et al. (2012) developed an approach to calculating absorbed doses in units of
Gys to livestock using the body shape of a deer to demonstrate the approach. Based on their
literature review and information from the Chernobyl accident, they concluded that estimated
absorbed doses of 1 Gy or less indicates that large animal livestock could be salvaged and doses
of 2 Gy and 3 Gy or less would indicate small animals and poultry, respectively, could be
salvaged (Brandl etal. 2012).
How to determine how many livestock might be salvageable following a nuclear incident,
however, is beyond the scope of this assessment. We provided this background to remind readers
that livestock exposed to fallout from a radiological incident do not necessarily need to be culled,
and information specific to an event is needed to make decisions.
B-15
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References for Appendix B
Brandl A, Johnson T, and Sprenger P. (2012). The calculation of dose to externally contaminated
livestock and animal triage for livestock handling and processing. In: Proceedings of the 13 th
IRPA [International Radiation Protection Association] International Congress—IRPA13
Glasgow, Scotland, 14-18 May 2012. Paper presented at Technical Session TS9b: Accident
Consequence Management. Retrieved September 25, 2016, from:
http//www. irpa. net/members/TS9b.3 .pdf
Dennison KM. (2016). Radiological response decisions: using science to guide animal and
agricultural emergency management. Presentation at the 2016 National Alliance of State
Animal and Agricultural Emergency Programs Summit. Texas A&M University, College
Station, Texas. Meeting presentation slides retrieved October 9, 2016, from Dennison
http://www.nasaaep.org/index htm files/Dennison%20-
Radiation%20Presentations%20combined.pdf
ENS (European Nuclear Society). (2013). Radiation weighting factors. In: Glossary ofNuclear
Terms. Cites COM(2012) 242 final, Brussels, 30.5.2012: Proposal for a Council Directive
laying down basic safety standards for protection against the dangers arising from exposure
to ionizing radiation. Retrieved October 12, 2016 from:
https//www.euronuclear.org/info/encyclopedia/r/radiation-weight-factor, htm
USEPA (2013). PAG Manual: Protective Action Guides and Planning Guidance for Radiological
Incidents. Draft for Interim Use and Public Comment. March. Available from:
https//www.epa.gov/sites/production/files/2015-06/documents/pag-manual-interim-pub lie-
comment-4-2-2013 .pdf
USNRC (U.S. Nuclear Regulatory Commission). (2016). Locations ofLow-level Radioactive
Waste Disposal Facilities. U.S. Nuclear Regulatory Commission. Website updated May 10,
2016. Retrieved June 26, 2017, from: https//www. nrc.gov/waste/llw-
disposal/licensing/locations.html
USNRC. (2014). Backgrounder on Dirty Bombs. Retrieved October 16, 2016, from
http//www. nrc.gov/reading-rm/doc-collections/fact-sheets/fs-dirty-bombs. html.
WNA (World Nuclear Association). (2016). Nuclear Radiation and Health Effects. World
Nuclear Association. Updated July. Available at: http://www.world-nuclear.org/information-
library/safety-and-security/safety-of-plants/chernobyl-accident.aspx
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