United States
Nuclear Regulatory
Commission
United States
Department of
Energy
United States
Environmental
Protection Agency
NUREG-1783
EPA 832-R-03-002A
DOE/EH-0670
Interagency Steering Committee on
Radiation Standards
Final Report
ISCORS Assessment of Radioactivity in Sewage
Sludge: Modeling to Assess Radiation Doses
ISCORS Technical Report 2004-03
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ISCORS Assessment of Radioactivity in Sewage
Sludge: Modeling to Assess Radiation Doses
Developed by the Sewage Sludge Subcommittee
United States
Nuclear
Regulatory
Commission
United States
Department of
Energy
United States
Environmental
Protection
Agency
State of New Jersey
Department of
Environmental
Protection
Middlesex County
Utilities
Authority
Northeast Ohio
Regional
Sewer District
ISCORS Technical Report 2004-03
Date Published: February 2005
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ABSTRACT
The treatment of municipal sewage at publicly owned treatment works (POTWs) leads to the
production of considerable amounts of residual solid material known as sewage sludge, which is
widely used in agriculture and land reclamation. Elevated levels of naturally-occurring and
man-made radionuclides have been found in sewage sludge samples, suggesting the possible
radiation exposure of POTW workers and members of the public. The Interagency Steering
Committee on Radiation Standards (ISCORS) therefore conducted a limited survey of
radioactivity in sewage sludge across the United States. Concurrently, to assess the levels of the
associated doses to people, it undertook to model the transport of the relevant radionuclides from
sewage sludge into the local environment. The modeling work consisted of two steps. First,
seven general scenarios were constructed to represent typical situations in which members of the
public or POTW workers may be exposed to sewage sludge. Then, the RESRAD multi-pathway
environmental transport model generated sewage sludge concentration-to-dose conversion
factors. This report describes the results of this dose modeling effort, and provides a complete
description and justification of the dose assessment methodology.
PAPERWORK REDUCTION ACT STATEMENT
This NUREG contains information collection requirements that are subject to the Paperwork
Reduction Act of 1995 (44 U.S.C. 3501 et seq.). These information collections were approved
by the Office of Management and Budget, approval numbers 3150-0014 and 3150-0189.
PUBLIC PROTECTION NOTIFICATION
The NRC may not conduct or sponsor, and a person is not required to respond to, a request for
information or an information collection requirement unless the requesting document displays a
currently valid OMB control number.
Final, February 2005 iii ISCORS Technical Report 2004-03
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CONTENTS
ABSTRACT iii
CONTENTS v
ACKNOWLEDGMENTS xi
EXECUTIVE SUMMARY xiii
1 INTRODUCTION 1-1
1.1 BACKGROUND 1-1
1.2 PREVIOUS DOSE ASSESSMENTS OF
RADIONUCLIDES IN SEWAGE SLUDGE 1-2
1.3 PURPOSE OF THE PRESENT ASSESSMENT 1-3
1.4 GENERAL APPROACH 1-4
1.5 ORGANIZATION OF THIS REPORT 1-4
2 ASSESSMENT METHODS OVERVIEW 2-1
2.1 OUTLINE OF THIS DOSE ASSESSMENT 2-1
2.2 EXPOSURE SCENARIOS 2-1
2.3 SELECTION OF THE MODEL CODE 2-2
2.4 PARAMETER VALUES AND DISTRIBUTIONS 2-5
2.4.1 FIXED VALUE AND DISTRIBUTIONS FOR
MODELING PARAMETERS 2-5
2.4.2 USE OF DISTRIBUTIONS IN
DETERMINISTIC CALCULATIONS 2-7
2.4.3 PRIORITIES IN PARAMETER SELECTION 2-7
2.5 INTERPRETATION OF RESULTS OF
THE PROBABILISTIC CALCULATIONS 2-7
2.6 SENSITIVITY, UNCERTAINTY, AND VARIABILITY 2-7
2.7 ASSESSMENT OF CONTRIBUTIONS FROM
INDOOR RADON PATHWAY 2-8
2.8 LIMITATIONS OF THE CURRENT ASSESSMENT 2-8
2.8.1 SOURCES 2-9
2.8.2 SCENARIOS 2-9
2.8.3 MODELS 2-9
3 SOURCE ANALYSES AND RELATED ISSUES 3-1
3.1 RADIONUCLIDES CONSIDERED IN THE DOSE ASSESSMENT 3-1
3.2 LAND APPLICATION SCENARIOS 3-4
3.2.1 SPECIFIC ACTIVITY IN SOIL-SLUDGE MIXTURE 3-4
3.2.2 MULTIPLE YEARS OF
APPLICATION AND WAITING PERIODS 3-5
3.2.3 OFFSITE AIR EXPOSURES 3-7
3.3 LANDFILL/IMPOUNDMENT NEIGHBOR SCENARIO 3-9
3.4 INCINERATOR NEIGHBOR SCENARIO 3-10
3.5 SLUDGE/ASH MANAGEMENT SCENARIOS 3-14
3.5.1 SLUDGE APPLICATION WORKER SOURCE 3-14
3.5.2 PUBLICLY OWNED TREATMENT WORKS
WORKER SOURCE 3-14
Final, February 2005 v ISCORS Technical Report 2004-03
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4 EXPOSURE SCENARIOS 4-1
4.1 ONSITE RESIDENT 4-1
4.2 RECREATIONAL USER ON RECLAIMED LAND SCENARIO 4-5
4.3 NEARBY TOWN RESIDENT SCENARIO 4-9
4.4 LANDFILL/SURFACE IMPOUNDMENT NEIGHBOR SCENARIO 4-12
4.5 INCINERATOR NEIGHBOR SCENARIO 4-17
4.6 SLUDGE APPLICATION WORKER SCENARIO 4-20
4.7 PUBLICLY OWNED TREATMENT WORKS WORKER SCENARIO . . . 4-23
4.7.1 SLUDGE SAMPLING 4-23
4.7.2 SLUDGE PROCESSING WITHIN
PUBLICLY OWNED TREATMENT WORKS 4-24
4.7.3 BIOSOLIDS LOADING/STORAGE 4-24
5 SENSITIVITY, AND UNCERTAINTY AND VARIABILITY 5-1
5.1 SENSITIVITY 5-1
5.2 SCENARIO UNCERTAINTY AND VARIABILITY 5-1
5.2.1 EXPOSURE ENVIRONMENT 5-1
5.2.2 EXPOSED POPULATIONS: CHILDREN/INFANTS 5-1
5.3 PARAMETER UNCERTAINTY AND VARIABILITY 5-2
5.4 MODEL UNCERTAINTY 5-5
5.4.1 TREATMENT OF SURFACE WATER 5-5
5.4.2 OFFSITE EXPOSURES 5-5
5.4.3 INFILTRATION RATE FOR LANDFILLS/SURFACE
IMPOUNDMENTS 5-6
6 SUMMARY OF DOSE-TO-SOURCE RATIOS 6-1
6.1 INTRODUCTION 6-1
6.2 LAND APPLICATION SCENARIOS 6-1
6.3 LANDFILL NEIGHBOR SCENARIO 6-8
6.4 INCINERATOR NEIGHBOR SCENARIO 6-12
6.5 OCCUPATIONAL SCENARIOS 6-13
6.5.1 SLUDGE APPLICATION WORKER 6-13
6.5.2 PUBLICLY OWNED TREATMENT WORKS
WORKER SCENARIOS 6-15
7 RADIATION DOSES CORRESPONDING TO THE RESULTS OF THE
ISCORS PUBLICLY OWNED TREATMENT WORKS SURVEY 7-1
7.1 RADIATION DOSES CORRESPONDING TO
SURVEY SAMPLE ACTIVITIES 7-1
7.2 CALCULATED DOSES FOR LAND APPLICATION SCENARIOS 7-3
7.3 CALCULATED DOSES FOR
LANDFILL/IMPOUNDMENT NEIGHBOR SCENARIO 7-4
7.4 CALCULATED DOSES FOR PUBLICLY OWNED
TREATMENT WORKS INCINERATOR NEIGHBOR SCENARIO 7-4
7.5 CALCULATED DOSES FOR PUBLICLY OWNED
TREATMENT WORKS SLUDGE/ASH WORKER SCENARIOS 7-4
7.6 UNCERTAINTY AND VARIABILITY IN CALCULATED DOSES 7-5
8 CONCLUSIONS 8-1
9 REFERENCES 9-1
ISCORS Technical Report 2004-03 vi Final, February 2005
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FIGURES
B.I Graphical Representation of Pathways Considered in RESRAD B-2
B.2 Graphical Representation of Pathways Considered in RESRAD-BUILD B-3
B.3 Parameter Distribution Input Screen B-4
B.4 Parameter Distribution Help Screen B-5
TABLES
ES. 1 Calculated Total Peak Dose from Survey Samples: Summary Results With and
Without Indoor Radon Contribution (mrem/year) xxi
1.1 Hypothetical Maximum Doses (mrem/year) 1-3
2.1 Comparison of Models 2-4
2.2 Scenarios and Models in this Assessment 2-5
3.1 Radionuclides Included in the Dose Assessment 3-2
3.2 Values of Deposition Velocity and Dispersion Factor, • /Q, for the Various
Radionuclides, Computed for the Nearby Town Scenario by CAP88-PC, for Input to
RESRAD-OFFSITE 3-8
3.3 Municipal Solid Waste Source Characteristics 3-9
3.4 Values of Deposition Velocity and Dispersion Factor, • /Q, for the Various
Radionuclides, Computed for the Landfill Neighbor Scenario by CAP88-PC, for
Input to RESRAD-OFFSITE 3-10
3.5 Incinerator Control Efficiencies, CE, and Release Rates, R release , for Various
Radionuclides 3-11
3.6 Values of Deposition Velocity and Dispersion Factor, • /Q, for the Various
Radionuclides, Computed for the Incinerator Neighbor Scenario by CAP88-PC, for
Input to RESRAD-OFFSITE 3-12
3.7 Decay Factor Adjustments for Incinerator Neighbor Scenario 3-13
4. la Onsite Resident Scenario Pathways 4-4
4.1b Onsite Resident Scenario and Sub-Scenario Parameters and Distributions 4-5
4.2a Recreational User on Reclaimed Land Pathways 4-7
4.2b Recreational User Scenario Parameters and Distributions 4-8
4.3a Nearby Town Resident Pathways 4-10
4.3b Nearby Town Resident Scenario and Sub-Scenario Parameters and Distributions
4-11
4.4a Landfill Neighbor Pathways—Post-Monitoring Period 4-14
4.4b Landfill Neighbor Scenario Parameter and Distributions—Post-Monitoring Period
4-15
4.5a Incinerator Neighbor Pathways 4-18
4.5b Incinerator Neighbor Scenario Parameters and Distributions 4-19
Final, February 2005 vii ISCORS Technical Report 2004-03
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4.5b Incinerator Neighbor Scenario Parameters and Distributions 4-20
4.6a Agricultural Application Worker Pathways 4-21
4.6b Agricultural Application Worker Scenario Parameters and Distributions 4-22
4.7a All POTW Worker Pathways 4-26
4.7b General POTW Worker Sub-Scenario Parameters and Distributions 4-27
5.1 Parameters and their Uncertainties and Variability 5-2
5.2 Parameter Uncertainty/Variability Results 5-4
6.1 Onsite Resident Scenario Total DSR Results (mrem/yr per pCi/g) 6-2
6.2 Onsite Resident Scenario Indoor Radon DSR Results (mrem/yr per pCi/g) 6-4
6.3 Recreational User Scenario Total DSR Results (mrem/yr per pCi/g) 6-5
6.4 Nearby Town Scenario Total DSR Results (mrem/yr per pCi/g) 6-6
6.5 Landfill Neighbor Scenario (Municipal Solid Waste) Total DSR Results (mrem/yr per
pCi/g) 6-8
6.6 Landfill Neighbor Scenario (MSW) Indoor Radon DSR Results (mrem/yr per pCi/g)
6-10
6.7 Landfill Neighbor Scenario (Surface Impoundment) Total DSR Results (mrem/yr per
pCi/g) 6-10
6.8 Landfill Neighbor Scenario (Surface Impoundment) Indoor Radon DSR Results
(mrem/yr per pCi/g) 6-11
6.9 Incinerator Neighbor Scenario Total DSR Results (mrem/yr per pCi/g) 6-12
6.10 Sludge Application Worker Scenario Total DSR Results (mrem/yr per pCi/g) .. 6-13
6.11 POTW Sampling Worker Scenario Total DSR Results (mrem/yr per pCi/g) .... 6-16
6.12 POTW Intra-POTW Transport Worker Scenario Total DSR Results (mrem/yr per
pCi/g) 6-17
6.13 POTW Intra-POTW Transport Worker Scenario Indoor Radon DSR Results
(mrem/yr per pCi/g) 6-18
6.14a POTW Biosolids Loading Worker Scenario Total DSR Results (mrem/yr per pCi/g)
6-19
6.14b POTW Biosolids Loading Worker Scenario Total DSR Results (mrem/yr per pCi/g)
for Ra-226 and Th-228 6-20
6.15 POTW Biosolids Loading Worker Scenario Indoor Radon DSR Results 6-21
7.1 Calculated Total Peak Dose (Total Effective Dose Equivalent-TEDE) from Survey
Samples: Summary Results With and Without Indoor Radon Contribution 7-2
7.2 Calculated Total Peak Radon Doses and Concentrations from Survey Samples . . 7-3
7.3 Source Variability and Parameter Variability and Uncertainty in Calculated Survey
Sample Doses 7-6
A. 1 Baseline Values and Distributions for the Kd Parameter A-2
A.2 Baseline Values and Distributions for the Plant Transfer Factor A-3
A.3 Baseline Values and Distribution for the Meat Transfer Factor A-4
ISCORS Technical Report 2004-03 viii Final, February 2005
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A.4 Baseline Values and Distributions for the Milk Transfer Factor A-5
A.5 Baseline Values and Distributions for the Aquatic Food (Fish) Transfer Factor . A-6
A.6 Probability Distribution Notations Used in Baseline Parameter Tables A-7
A.7 RESRAD Baseline Parameter Values and Distributions A-8
A.8 RESRAD Baseline Parameter Correlations for Probabilistic Analyses A-21
A.9 RESRAD-Offsite Baseline Parameter Values and Distributions A-22
A. 10 RESRAD-Offsite Baseline Parameter Correlations for Probabilistic Analyses . A-56
A.I 1 RESRAD-BUILD Baseline Parameter Values and Distributions A-60
B.I Listing of Input Data and Information Needed for Sample Generation B-6
C. 1 Volatilization Fractions Recommended by Oztunali and Roles (1984) for the
Reference Pathological and Hazardous Waste Incinerators C-4
C.2 Summary Range of Partitioning Values Found in the
Literature by Aaberg et al. (1995a) C-4
C.3 Element Partitioning Assumptions Used by Aaberg et al. (1995a) C-5
C.4 Summary of Data Presented by Liekhus et al. (1997) for
Normalized Mass Percent of Feed Element in Bottom Ash
(information adapted from Table 4-11 of Liekhus et al.) C-7
C.5 Summary of Data Presented by Liekhus et al. (1997) for
Normalized Mass Percent of Feed Element Captured by the Air Pollution Control
System (information adapted from Table 4-12 of Liekhus et al.) C-8
C.6 Average Control Efficiencies for the
Easterly, Southerly, and Westerly Incinerators C-9
D. 1 Radon Dosimetry Conversions Used in RESRAD and RESRAD-BUILD D-l
D.2 Time Fractions and WL to WLM Conversion Factors D-l
E.I Onsite Resident DSR Percentiles (mrem/yr per pCi/g in Sewage Sludge) E-2
E.2 Recreational User DSR Percentiles (mrem/yr per pCi/g in Sewage Sludge) E-3
E.3 Nearby Town DSR Percentiles (mrem/yr per pCi/g in Sewage Sludge)
(One Year of Application) E-4
E.4a Landfill (Municipal Solid Waste) Neighbor
(mrem/yr per pCi/g in Sewage Sludge) E-5
E.4b Landfill (Surface Impoundment) Neighbor
(mrem/yr per pCi/g in Sewage Sludge) E-6
E.5 Incinerator Neighbor (mrem/yr per pCi/g in Sewage Sludge) E-7
E.6 Sludge Application Worker (mrem/yr per pCi/g in Sewage Sludge) E-8
E.7a POTW Worker: Biosolids Loading (mrem/yr per pCi/g in Sewage Sludge) E-9
E.7b POTW Worker: Biosolids Loading for Ra-226 and
Combinations of Air Exchange Rate and Building Height E-10
E.7c POTW Worker: Biosolids Loading for Th-228 and
Combinations of Air Exchange Rate and Building Height E-10
Final, February 2005 ix ISCORS Technical Report 2004-03
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APPENDICES
A Baseline Parameter Values and Distributions A-l
A.I Introduction A-l
A.2 Parameters Used in Multiple Codes A-l
A.3 Code-Specific Parameters A-7
B RESRAD and RESRAD-BUILD Codes B-l
B. 1 Introduction B-l
B.2 Probabilistic Modules B-4
B.2.1 Overview B-4
B.2.2 Sampling Method B-5
B.2.3 Distribution of Parameters B-8
B.2.4 Probabilistic Results B-8
B.3 References B-9
C Incinerator Control/Release Fractions C-l
C. 1 Introduction C-l
C.2 Regulatory Values for Release Fraction C-l
C.3 Assessment of Aaberg et al. (1995a) C-l
C.4 Review by Liekhus et al. (1997) C-2
C.5 Part 503 Metals Partitioning Information C-3
C.6 Summary C-3
C.7 References C-9
D Conversion Between Radon Doses and Working Level Concentrations D-l
D.I Dose- and Concentration-To-Source Ratios in Working Level Units D-l
D.2 Development of Publicly Owned Treatment Works
Loading Worker Radon Dose Fitting Functions D-2
E Probabilistic Percentiles for Dose-to-Source Ratios E-l
F Responses to Peer Review Comments on ISCORS Dose Modeling Document F-l
F.I Overview of Peer/General Review Process F-l
F.2 Positive Comments F-3
F.3 Comments Requiring Response F-3
F.3.1 Documentation/Presentation F-3
F.3.2 Scenarios/Parameters F-4
F.4 Modeling F-6
F.5 Sensitivity/Uncertainty F-7
F.6 Validation F-8
ISCORS Technical Report 2004-03 x Final, February 2005
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ACKNOWLEDGMENTS
The Sewage Sludge Subcommittee of the Federal ISCORS (1) conducted a survey to collect
information concerning radioactive materials in sewage sludge and ash from POTWs;
(2) performed dose modeling to help with the interpretation of the results of the survey; and
(3) developed a guidance on radioactive materials in sewage sludge and ash for POTW owners
and operators. Subcommittee members who actively participated in the development of the three
reports associated with this project include the following (listed alphabetically):
Lee Abramson, NRG/Office of Nuclear Regulatory Research
Kevin Aiello, Middlesex County (New Jersey) Utilities Authority
James Bachmaier, DOE/Office of Environment, Safety and Health
Bob Bastian, EPA/Office of Wastewater Management
Lydia Chang, NRG/Office of Nuclear Material Safety and Safeguards
Weihsueh Chiu, EPA/Office of Research and Development
Chris Daily, NRG/Office of Nuclear Regulatory Research
Mark Doehnert, EPA/Office of Radiation and Indoor Air
Giorgio Gnugnoli, NRG/Office of Nuclear Material Safety and Safeguards
Paula Goode, EPA/EP A/Office of Radiation and Indoor Air
Jenny Goodman, New Jersey Department of Environmental Protection
Dale Hoffmeyer, EPA/Office of Radiation and Indoor Air
Rosemary Hogan, NRG/Office of Nuclear Regulatory Research
Anthony Huffert, NRG/Office of Nuclear Material Safety and Safeguards
Andrea Jones, NRG/Office of Nuclear Regulatory Research
Judy Kosovich, DOE/Office of General Counsel
Tom Lenhart, Northeast Ohio Regional Sewer District
Jill Lipoti, New Jersey Department of Environmental Protection
Roy Lovett, Department of Defense
Tin Mo, NRG/Office of Nuclear Regulatory Research
Donna Moser, NRC/Region II, Division of Nuclear Materials Safety
Robert Neel, NRG/Office of Nuclear Material Safety and Safeguards
Bob Nelson, NRG/Office of Nuclear Material Safety and Safeguards
Tom Nicholson, NRG/Office of Nuclear Regulatory Research
Tom O'Brien, NRG/Office of State and Tribal Programs
William R. Ott, NRG/Office of Nuclear Regulatory Research
Hal Peterson, DOE/Office of Environment, Safety and Health
Alan Rubin, EPA/Office of Water
Steve Salomon, NRG/Office of State and Tribal Programs
Patricia Santiago, NRG/Office of Nuclear Material Safety and Safeguards
Dave Saunders, EPA/National Air and Radiation Environmental Laboratory
Duane Schmidt, NRG/Office of Nuclear Material Safety and Safeguards
Loren Setlow, EPA/Office of Radiation and Indoor Air
Behram Shroff, EPA/Office of Radiation and Indoor Air
Phyllis Sobel, NRG/Office of Nuclear Material Safety and Safeguards
Scott Telofski, EPA/National Air and Radiation Environmental Laboratory
Mary Thomas, NRC/RIII, Division of Nuclear Materials
Final, February 2005 xi ISCORS Technical Report 2004-03
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Mary Wisdom, EPA/National Air and Radiation Environmental Laboratory
Anthony Wolbarst, EPA/Office of Radiation and Indoor Air
The Subcommittee acknowledges the technical support provided by staff of the Environmental
Assessment Division of Argonne National Laboratory in performing these calculations and in
helping prepare this report. These individuals include the following (listed alphabetically):
Jing-Jy Cheng
Sunita Kamboj
Charley Yu
ISCORS Technical Report 2004-03 xii Final, February 2005
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EXECUTIVE SUMMARY
INTRODUCTION
The processing of municipal sewage at publicly owned treatment works (POTWs) leads to the
production of considerable amounts of residual waste materials known as sewage sludge or
biosolids. In addition, some POTWs incinerate sewage sludge onsite, producing a dry ash
residual.
Sewage sludge contains detectable amounts of radioactive materials. In addition, sewage
flowing into a POTW can include anthropogenic materials exempt from regulatory control, such
as excreta from individuals undergoing medical diagnosis or therapy, and discharges of limited
quantities of radioactive materials from some licensees of the U.S. Nuclear Regulatory
Commission (NRC) and NRC Agreement State licensees. NRC estimates that of the more than
22,000 regulated users of Atomic Energy Act (AEA) radioactive materials, about 9,000 have the
potential to release radioactive materials to municipal sewer systems.
Other sources of radioactive materials that may enter sewage collection systems include: storm
water runoff, groundwater, surface water, residuals from drinking water treatment plants, and
waste streams from certain industries (e.g., ceramics, electronics, optics, mining, petroleum,
foundries, and pulp/paper mills). All of these waste streams may contain naturally occurring
radioactive materials (NORM), including naturally occurring radioactive materials whose
radionuclide content, or the potential for exposure to humans and the environment, has been
technologically enhanced by human activities (TENORM). Federal and State regulations limit
the amounts of anthropogenic sources and some sources of TENORM that could otherwise be
intentionally disposed of in the sewage systems. These regulations, however, do not apply to all
sources of NORM and TENORM.
Sewage treatment processes include filtration, precipitation, and other techniques for removing
solids and associated trace heavy metals from the wastewater prior to discharge. These same
processes, however, will inadvertently cause radioactive materials that entered the sewer system
to become concentrated in the sewage sludge, and POTW workers managing the sludge will be
exposed to small amounts of radiation from these materials.
Treated sewage sludge is often applied to land as a source of organic material or nutrients as a
part of agricultural and land reclamation operations. As a result, equipment operators who apply
the sewage sludge, farmers, consumers of the farm products, or those who spend time on
reclaimed land, will be exposed to small amounts of radiation from radioactive materials in the
sewage sludge. The current Federal regulation at 40 CFR Part 503, which applies to the use or
disposal of sewage sludge, limits levels of heavy metals and pathogens. At present, however,
there are no Federal regulations in place that limit levels of radioactive materials in sewage
sludge or ash.
There have been no identified situations in the U.S. where radioactive materials in sewage sludge
have posed a significant threat to the health and safety of POTW workers or the general public.
Final, February 2005 xiii ISCORS Technical Report 2004-03
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There are, however, a number of facilities where elevated levels of radioactive materials have
been detected. Also, some states have identified cases where radium from drinking water
treatment residuals has been concentrated in sewage sludge. These situations made clear the
need to assess the levels of radionuclides present in sewage sludge and ash around the country,
and to assess the potential for human exposure to such materials.
In response to that need, and to Congressional interest, the Federal Interagency Steering
Committee on Radiation Standards (ISCORS) formed a Sewage Sludge Subcommittee to assess
the levels of radioactivity in sewage sludge and ash nationwide, and to determine whether there
is a public health problem that needs to be addressed1. The Subcommittee conducted a limited,
voluntary survey involving samples from 313 POTWs across the United States, and has used the
results of that survey to evaluate potential human exposure to radiation from radioactive
materials in sewage sludge and ash. In a Federal Register notice published on
November 26, 2003 (68 FR 66503), ISCORS announced the availability of a final report entitled
ISCORS Assessment of Radioactivity in Sewage Sludge: Radiological Survey Results and
Analysis (ISCORS 2003-02). That report has also been posted on the ISCORS website
(http://www.iscors.org), along with the associated survey data base.
The Federal Register notice also requested public comments on two associated documents. The
present document, ISCORS Assessment of Radioactivity in Sewage Sludge: Modeling to Assess
Radiation Doses (ISCORS 2004-03), is the final version of a report on the dose modeling
conducted by ISCORS. It contains revisions made in response both to a formal scientific peer
review and to valuable comments from the public. The report is intended to be complete, such
that when used in conjunction with the RESRAD family of environmental pathway modeling
codes, every result in it can be independently reproduced by other modelers.
The other document was a draft report, now finalized as ISCORS Assessment of Radioactivity in
Sewage Sludge: Recommendations on Management of Radioactive Materials in Sewage Sludge
and Ash at Publicly Owned Treatment Works (ISCORS 2004-04).
GENERAL APPROACH TO THE MODELING
The Subcommittee undertook this analysis of possible doses to POTW workers and members of
the general public for two primary purposes: (1) to assist in interpreting the survey results and
assessing the potential exposures, and (2) to support development of recommendations to POTW
operators.
The general approach of the study consisted of two steps. First, a suitable number of generic
scenarios, encompassing multiple environmental transport and exposure pathways, were
1 ISCORS is co-chaired by the U.S. Environmental Protection Agency (EPA) and the U.S. Nuclear Regulatory
Commission (NRC), and also has representatives from the U.S. Departments of Energy (DOE), Department of
Defense (DOD), Health and Human Services (DHHS), and Labor (DOL), and observers from White House
Office of Management and Budget (OMB), the Office of Science and Technology Policy (OSTP), and various
states. Subcommittee members are representatives of EPA, NRC, DOE, the State of New Jersey, the Middlesex
County Utilities Authority, and the Northeast Ohio Regional Sewer District.
ISCORS Technical Report 2004-03 xiv Final, February 2005
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designed so as to represent situations in which POTW workers or members of the public are
most likely to be exposed to sewage sludge through typical sludge management practices. Then,
assuming a reference specific activity (1 picocurie per gram of dry sewage sludge, or
37 Becquerel per kilogram, in SI units) of a single radionuclide, a widely-accepted, stochastic,
multi-pathway environmental transport model (RESRAD) was employed to obtain a
radionuclide-specific sludge concentration-to-dose conversion factor for every scenario.
The selection of radionuclides for consideration was based primarily on the results of the
ISCORS survey of sewage sludge and ash at various POTWs, and the selected radionuclides
include manmade and naturally-occurring isotopes. The survey reported the detection of
8 radionuclides (Be-7, Bi-214,1-131, K-40, Pb-212, Pb-214, Ra-226, and Ra-228) in more than
200 samples. The dose modeling covers these radionuclides, along with others found by
spectroscopy during the full ISCORS survey. Several radionuclides not identified in the POTW
survey have been included in the analysis because they are either a parent or a daughter of a
radionuclide that was found in the survey (e.g., Ac-227, Np-237, Pa-231, Po-210, Th-229,
U-233, andXe-131m).
The output of the modeling was a set of dose-to-source ratios (DSRs), one for each combination
of radionuclide and scenario. DSRs are factors for converting specific activities (concentrations,
in pCi/g or Bq/kg) of radionuclides in sewage sludge to the peak Total Effective Dose
Equivalent (TEDE, in rems or sieverts) occurring over the 1000-year calculational period.
This dose modeling analysis was probabilistic. A probabilistic (also known as a stochastic or
Monte Carlo) calculation allows study of the uncertainty in dose assessment caused by uncertain
input parameters. The dose calculations were repeated multiple times as certain parameters
randomly assume ranges of numbers to reflect the uncertainties in the parameter values; each of
these calculations generates its own DSR. The results were presented in a cumulative
distribution function table, which records the probability that the "true" DSR-value is at or below
any specified value. The 95%-DSR value for some radionuclide and scenario, for example, is
greater than 95% of the hundreds of DSR-values calculated in the analysis, and smaller than only
5% of them. In other words, in 95% of the situations that might be modeled in this manner, the
"true" DSR would be less than its listed 95th-percentile value, and in the majority of cases, it
would be much less.
The dose modeling scenarios cover a wide range of typical exposure conditions found across the
country, and they allow for considerable variability. Guided in part by examples from previous
dose assessments by DOE, EPA, and NRC, ISCORS developed scenarios that are simple and
generic (i.e., not based on the unique characteristics of any particular site or sites), and the
scenarios are general enough to account for the most common sewage sludge and ash
management practices. The scenarios represent a variety of different uses or disposal options for
sewage sludge, and consider those situations where radiation exposures are most likely to occur.
For each scenario, all the standard environmental transport and exposure pathways were
incorporated: direct exposure to gamma rays resuspension of dust; inhalation of dust and indoor
and outdoor radon; leaching into groundwater; and ingestion of well and surface water,
Final, February 2005 xv ISCORS Technical Report 2004-03
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vegetables, fruit, meat, milk, and fish, any of which are obtained or produced onsite—along with
ingestion of small amounts of soil. The seven scenarios are:
Exposure Onsite
1. Residents of a house built on a former agricultural field where sewage sludge was applied
2. Recreational visitors to a park where sewage sludge has been used in land reclamation
Exposure on Neighboring Site
3. Residents of a town near a sewage sludge land-application site
4. Neighbors of a landfill that contains sewage sludge or ash
5. Neighbors of an operating sludge incinerator
Occupational Exposure
6. Workers who operate equipment to apply sewage sludge to agricultural lands
7. Workers at a POTW involved in sewage sludge sampling, transport, or loading operations.
These scenarios were designed to form the basis for performing conservative but realistic
assessments of the doses of ionizing radiation associated with typical sewage sludge
management practices. They were not intended to represent 'worst case' scenarios.
After a number of computer-based environmental pathway models were considered for use in
this effort, the RESRAD family of codes, including RESRAD version 6.0, RESRAD-BUILD
version 3.0, and RESRAD-OFFSITE version 1.0, was selected largely because of its flexibility
in scenario development (RESRAD 2000). RESRAD contains the necessary data on most
relevant radionuclides. Other radionuclides were added for this effort. While all transport and
exposure pathways of interest are included, the codes employ a manageable number of
parameters (about 140 for RESRAD, 300 for RESRAD-OFFSITE, and 40 for RESRAD-BUILD)
and contain built-in sensitivity and probabilistic uncertainty analysis modules. RESRAD is
widely used, well documented, and user-friendly, so that the calculations can be readily
replicated or modified by others.2
Because Scenarios 1, 2, and 6 involve only onsite receptors, their doses can be estimated using
RESRAD Version 6. Scenarios 3, 4, and 5 are complicated by offsite transport and are examined
with the RESRAD-OFFSITE code; as part of the calculation, the CAP88-PC code accounts for
airborne transport of radioactive material away from the source. Some workers at the POTW
2 RESRAD-OFFSITE is a recent addition to this family of codes. It implements the same general approach that is
used in many other codes for simple offsite transport problems, and should be generally acceptable to experts in
the field for relatively simple generic calculations, but it is not yet well documented or extensively used.
ISCORS Technical Report 2004-03 xvi Final, February 2005
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(Scenario 7) spend a considerable amount of time indoors, requiring the use of the RESRAD-
BUILD code.
For nearly all the modeling parameters, a set of baseline parameter values and distributions,
which do not change from scenario to scenario, were selected for application to all seven
scenarios. Many of these parameter values and distributions are RESRAD default values, and
others appear in EP'A''s Exposure Factors Handbook (EPA 1997), NRC's NUREG/CR-6697
(NRC 2000b), and similar compilations. Human metabolic and behavioral data, such as
inhalation and ingestion rates under various conditions, were based on national databases that are
generally accepted by regulatory agencies such as EPA and NRC. On those few occasions that
standard generic and default values and distributions were not adopted, explanations are
provided.
The relatively small number of parameter values and distributions that are scenario-specific and
distinguish the scenarios from one another may be thought of as variations from the baseline.
These have been tabulated explicitly for each scenario.
The computation of soil concentration is complicated by radionuclide decay and ingrowth, and
by leaching and erosion. This is especially true for Scenarios 1, 3, 5, and 6, for which there are
multiple sewage sludge applications over a period of years. RESRAD does not currently
compute out Monte Carlo calculations that involve more than one sewage sludge application. To
extrapolate from single-year (obtained with a probabilistic calculation) to multiple-year
application, approximate scaling factors have been developed and presented in tables, as
described in the report.
EXPOSURE SCENARIOS AND
ASSOCIATED MODELING PARAMETERS
The assessment for every exposure scenario starts off with the creation of a conceptual model of
the site. This model describes the spatial and temporal distribution of sewage sludge/ash in
surface soil (the source term), the characteristics of the sub-surface soil, the occurrence of
surface and ground water, the abundance of vegetation, and the presence of farm animals. Also
crucial are the environmental transport and human exposure pathways potentially at work, such
as the blowing of dust by wind, irrigation of fodder with groundwater, and the behavioral
patterns of the humans who may be exposed.
The description of each scenario is then expressed, to the extent possible, as a specific set of
parameter values and distributions chosen as inputs to the relevant RESRAD code. The
selection of a particular model (with its built-in assumptions and approximations) and a set of
parameter values and distributions (baseline plus any that are site-specific) completely defines
the characteristics of the site and of the exposed population for the dose calculation.
The scenario description and the associated set of input parameters establish the degree of
conservatism of the modeling. The scenarios in this study were modeled using "realistic"
distributions and values for most pathway and exposure parameters. The objective was to
Final, February 2005 xvii ISCORS Technical Report 2004-03
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estimate doses to the individuals most likely to be exposed to radioactive material from sewage
sludge (i.e., "members of the critical group") for each scenario, and 95th-percentile DSR values
were adopted for the assessment. The critical group consists of the sub-population with
relatively high exposure to sewage sludge; the scenarios represent reasonably conservative
conditions for calculating doses.
The Seven Exposure Scenarios
1. In risk assessments, the resident farmer family is often modeled as a reasonable but bounding
case study. But many new houses are now constructed on former farmlands near urban areas;
so the report considers the similar, but much more common, situation of Onsite Residents who
inhabit a home built on land previously used for farming, and who ingest some water and food
obtained onsite. The source of radioactive material is a farm-field that was amended with
sludge-based fertilizer either one time recently, or annually for the past 5 years, 20 years,
50 years, or 100 years. (Very few land application sites in the country are known to have
applied sewage sludge annually for more than 20 years; the 50- and 100-year computations
were included primarily for consistency with the technical support for EPA's Standards for
the Use or Disposal of Sewage Sludge at 40 CFR 503, as a check on the data analysis
methodology, and to assist POTW operators in their consideration of future sewage sludge
management practices.)
2. A Recreational User occasionally spends time on land that was severely disturbed by mining
or excavation, followed by a reclamation effort that included a single large application of
sewage sludge and other soil additives. Three years after a sludge application, when a
sustainable vegetative cover is in place, the site is opened to the public, but exclusively for
hiking, camping, picnicking, boating, hunting, fishing, and other recreational uses.
3. The Nearby-Town Resident scenario assesses the doses to members of the critical group who
live in a town, the proximal edge of which is located about 0.8 km (0.5 mile) downwind and
downstream (for both ground- and surface-water) from an agricultural field where sludge has
been applied for one or more years. All exposure pathways involve physical transport (and
dilution) of radionuclides from the source field to the town or to neighboring fields, mainly
through airborne transport of contaminated dust.
4. Two sub-cases for the Landfill/Surface Impoundment Neighbor scenario were designed for the
study of the near-surface burial of sludge and ash: (1) a 1-hectare (about 2 acres),
2-meter-deep municipal solid waste (MSW) landfill; and (2) a surface impoundment of the
same dimensions. Either form of disposal could affect someone who lives in a house sited
150 meters from the boundary, does some gardening, and raises a few animals for personal
consumption.
5. The Incinerator Neighbor scenario considers the potential for exposure of a member of the
public residing near a typical sewage sludge incineration facility. The incinerator burns
de-watered sludge on an ongoing basis, and the resulting particulate-containing exhaust gas is
released from the top of a stack as a plume, some of which settles onto the neighbor's
property. An exposed individual resides on a small farm located at the downwind point of
ISCORS Technical Report 2004-03 xviii Final, February 2005
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maximum average radionuclide air-concentration at ground level, and receives dose from
external exposure, inhalation, and ingestion.
6. A Sludge Application Worker typically drives or works on a truck, tractor, or other vehicle
that dispenses liquid, de-watered, or dried sludge at a constant rate on fields. The sources of
exposure will be the field itself and, to a lesser extent, the sludge loaded on the truck, but the
vehicle itself provides distance and some shielding from the source material. These exposures
are calculated both for the sludge being applied at the time as well as sludge applied from
previous applications (for 5 years, 20 years, 50 yeasr, and 100 years).
7. There is a high degree of variability in the jobs that POTW Workers perform when treating
and handling sludge. Still, there appear to be at least three tasks that are representative and
that may give rise to relatively high exposures to the sludge. These involve sludge sampling
and sample transport to the lab for analysis, sludge transport on an open conveyor belt, and
biosolids loading operations (e.g., filling trucks with sludge using a front-end loader). For all
three sub-scenarios, exposures are due primarily to direct gamma exposure and radon (if
radon precursors are present). For biosolids loading, dust inhalation also is a possible
exposure pathway.
RADIATION DOSES CORRESPONDING TO THE
ISCORS SURVEY RESULTS
Given a set of measured radionuclide activities in a real sewage sludge or ash sample from the
POTW Survey, the computed DSRs for each of the seven hypothetical scenarios can be used to
estimate the corresponding doses that potentially would be imparted to members of the critical
population group.
For every scenario and radionuclide combination, the dose was calculated, using the 95th-
percentile DSR, for every sludge and ash sample from the ISCORS national survey. The results
were ordered as an increasing sequence of dose values; the 95th-percentile dose is that which
exceeds 95% of the set of calculated doses. The median and the 95th-percentile values were
tabulated and presented in this report.
The only non-POTW scenario of potential concern is the onsite resident who, as expected,
received the highest dose. The greatest contributors to dose are NORM or TENORM sources,
and the pathway of greatest importance is that of indoor radon-222 and its daughters. Radon is
responsible for 65%-75% of the calculated doses, and direct gamma ray exposure from radium
for another 20%.
For some long-lived radionuclides that do not percolate rapidly through soil (in particular,
Ra-226), doses scale approximately linearly with number of applications. But when interpreting
the dose to the On-site Resident for 100, or even 50, applications, one should bear in mind that
these two long-term subscenarios were not included in the modeling out of any expectation that
many such sites will exist in the foreseeable future.
Final, February 2005 xix ISCORS Technical Report 2004-03
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The most exposed POTW employee is the Loading Worker. NORM and TENORM are again
the primary source, and indoor radon is dominant, with Rn-220 and Rn-222 and their daughters
responsible for 94% of the total calculated dose. As with the Onsite Resident, however, the
radon dose for this subscenario is highly dependent on the particular characteristics of the site, in
this case, on the details of the air-exchange rate and the size of the room that contains the sludge.
The TEDE results (both with and without the indoor radon contribution) for the 95th-percentile
concentration values from the ISCORS survey are summarized in Table ES-1.
CONCLUSION
This report describes the methodology and the results of computations undertaken to assess the
potential radiation exposures associated with the handling, and the disposal or beneficial use, of
sewage sludge that contains naturally occurring or man-made radioactive materials. A primary
objective of the study has been to provide perspective on the levels of radionuclides detected in
the ISCORS POTW Survey, taking into account typical sludge management practices.
The scenarios are intended to represent realistic situations that are likely to lead to conservative,
but not worst-case, radiation exposure assessments. While it has not been feasible to consider a
large number of distinct hypothetical situations, great effort has been made to ensure that the
scenarios constructed and analyzed here represent a reasonable range of exposure conditions,
without being overly conservative. In unique or unusual circumstances, real site-specific
exposures may be greater.3
3 Application of the modeling framework described here, but with site-specific values and distributions for
sensitive parameters, may provide a helpful preliminary analysis for the POTW operator who seeks to evaluate
levels of radioactive materials detected in sludge or ash. A comprehensive site assessment, however, might
require adoption of a more detailed, site-specific model to account for actual site conditions.
ISCORS Technical Report 2004-03 xx Final, February 2005
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Table ES.1 Calculated Total Peak Dose from Survey Samples: Summary Results
With and Without Indoor Radon Contribution (mrem/year)
Scenario
SI— Onsite
Resident
S2—
Recreational User
S3— Nearby Town
S4— Landfill
S5 — Incinerator
S6— Sludge
Application Worker
S7— POTW
Workers
Subscenario
1 year of appl.
5
20
50*
100*
N/A
1 yr of appl.
5
20
50*
100*
MSW - Sludge
MSW - Ash
Impoundment
N/A
1 yr of appl.
5
20
50*
100*
Sampling
(mrem/sample)
Transport
(mrem/hr)
Loading
95% sample
TEDE
(mrem/yr)
3
14
55
130
260
0.22
3.2e-03
0.014
0.045
0.094
0.17
0.027
0.041
1.2
7.7
0.15
0.77
3
7.4
15
4.9e-07
1.9e-04
17-70§
TEDE w/o Rn
(mrem/yr)
1
4.9
16
37
69
~
-
~
~
-
~
0.01
0.014
0.36
~
-
~
~
-
~
~
5.6e-05
13
Dominant
Radionuclide(s)
[pathways]
Ra-226 [indoor
radon]
Ra-226 [external]
Ra-226 [outdoor
radon]
Ra-226 [indoor
radon]
Ra-226 [indoor
radon]
Ra-226 [indoor
radon]
multiple [multiple]
Ra-226 [external]
Ra-226 [external]
Th-228 [indoor
radon, external]
Ra-226, Th-228
[indoor radon]
Notes:
* There are very few land application sites in the country that are known to have applied sewage sludge annually for more than 20 years;
the 50- and 100-year computations were included as a check on the data analysis methodology, and for the information of POTW
operators in their consideration of future sludge management practices.
§ Range represents results from the nine combinations of air exchange rate and room height (see Section 4.7.3).
- All values rounded to two significant figures.
- 95% DSRs are used in all total peak dose calculations.
- A "— " denotes that indoor radon was not separately calculated.
- N/A denotes Not Applicable.
MSW denotes Municipal Solid Waste.
- POTW and sludge applications workers perform tasks that lead to potentially significant exposures 1,000 hours per year.
Final, February 2005
xxi
ISCORS Technical Report 2004-03
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This study utilizes an existing, well-established model and relatively simple, generalized
scenarios that make possible an overall assessment without need for a large amount of
site-specific data. There are many factors—such as fracture flow, soluble and colloidal
transport, the impact of the POTW sludge de-watering operations on the transport and
bio-availability of radionuclides, year-to-year and seasonal changes in environmental
conditions—that would impact individual, real-site assessments but are not included here.
Others, such as indoor air exchange rates, room sizes, and the number of hours each year that
workers are exposed, have been modified based on peer review and comments from the general
public.
The computations have been carried out with probabilistic versions of three members of a
widely-employed family of environmental transport codes: RESRAD, RESRAD-OFFSITE, and
RESRAD-BUILD. The principal outputs are the tables of Dose-to-Source Ratios (DSR) for the
relevant radionuclides and the estimated doses, for seven hypothetical sludge-management
scenarios.
As expected, the DSR values range widely within each scenario for the various radionuclides,
and there are significant variances among the scenarios. These differences, however, are
meaningful only when considered in the context of the concentrations in sludge actually found in
the POTW Survey. Combining the computed DSRs with the survey measurements indicates that
most scenarios and radionuclides give rise to very low doses, but there are a few low-probability
radionuclide-scenario combinations that might be of health concern.
If agricultural land application of treated sewage sludge that contains elevated levels of
radioactive materials is carried out annually for many years (decades), then the potential exists
for future significant radiation exposure to a future onsite resident, primarily due to indoor radon
from NORM and TENORM. Additionally, when POTW workers are in a room with large
quantities of sludge (e.g., for storage or loading) and the air exchange rate is unusually low, there
exists the potential for significant exposure, again attributable mainly to radon.
Recommendations addressing these situations are provided in the companion final report,
ISCORSAssessment of Radioactivity in Sewage Sludge: Recommendations on Management of
Radioactive Materials in Sewage Sludge and Ash at Publicly Owned Treatment Works
(ISCORS 2004-04).
ISCORS Technical Report 2004-03 xxii Final, February 2005
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1 INTRODUCTION
1.1 BACKGROUND
The treatment of municipal sewage at publicly owned treatment works (POTWs) leads to the
production of considerable amounts of residual solid material, which is known as sewage sludge
(or "municipal sewage sludge" or "sludge").
Sewage flowing into a POTW may contain naturally occurring radioactive materials (NORM) or
manmade radionuclides. Groundwater, surface water, water residues from drinking water
treatment plants, and waste streams from certain industries (ceramics, electronics, optics) that
discharge into sanitary sewers may contain elevated NORM radionuclides. Also entering sewers
may be surface water runoff containing fallout; excreta from individuals undergoing medical
diagnosis or therapy; licensed discharges of limited quantities of radioactive materials from DOE
facilities, NRC licensees, and Agreement State licensees; and anthropogenic materials exempt
from licensing. (NRC regulations allowing licensees to dispose of small amounts of licensed
radionuclides into a sanitary sewer system may be found in the Code of Federal Regulations at
10 CFR 20.2003.) The sewage treatment process, in turn, may lead to concentration in sludge of
the radioactive materials that entered into the sanitary sewer system.
Radioactive materials in sludge may cause radiation exposure both of POTW workers and of
members of the public. Municipal sewage sludge is often used as a source of organic material in
agriculture and land reclamation, for example, and thus may expose farmers and consumers of
the farm products, or those who spend time on reclaimed land. EPA's current standard at
40 CFR Part 503 for the use or disposal of municipal sewage sludge protects humans from heavy
metals and pathogens, but it does not include radionuclide limits. Indeed, there are currently no
Federal regulations regarding radionuclides in sewage sludge or in the ash from incinerated
sewage sludge (or "sewage sludge ash" or "ash").
There have been a number of cases of radionuclides discovered in sewage sludge and ash, and
some of these have lead to expensive cleanup projects (GAO 1994). These incidents made clear
the need for a comprehensive determination of the prevalence of radionuclides in POTW sewage
sludge and ash around the country, and the level of potential threat posed to human health and
the environment by various levels of such materials.
Final, February 2005 1-1 ISCORS Technical Report 2004-03
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In response to this need, the Interagency Steering Committee on Radiation Standards (ISCORS)1
formed a Sewage Sludge Subcommittee (Subcommittee)2 to coordinate, evaluate, and resolve
issues regarding radioactive materials in sewage sludge and ash. To provide a reasonable bound
on the amounts of radionuclides that actually occur in sewage sludge and ash, EPA and NRC, in
consultations with this Subcommittee, have conducted a limited survey of radioactivity in sludge
and ash across the United States. Concurrently, the Dose Modeling Workgroup of the
Subcommittee has undertaken a dose assessment to help assess the potential threat that these
materials may pose to human health. This report describes the methodology and results of that
dose modeling effort.
1.2 PREVIOUS DOSE ASSESSMENTS OF RADIONUCLIDES IN
SEWAGE SLUDGE
In the past, several groups have carried out examinations of potential radiation doses from
radionuclides in sewage sludge.
The DOE's Pacific Northwest National Laboratory (PNNL) conducted a scoping study in 1992
for the NRC (NRC 1992a) to evaluate the potential radiological doses to POTW workers and
members of the public from exposure to radionuclides in sewage sludge. The first part of the
analysis examined known cases of radioactive materials detected at POTWs and estimated the
potential doses to workers. The doses from these actual case studies were generally within
regulatory dose limits for members of the public.
The PNNL study went on to estimate maximum radiation exposures to POTW workers and
others who could be affected by low levels of man-made radioactivity in wastewater
(Kennedy et al. 1992). The study, which did not consider NORM/TENORM, used scenarios,
assumptions, and parameter values generally selected in a manner to produce prudently
conservative estimates of individual radiation doses. However, the quantities of radionuclides
released into the sewer systems were assumed to be the maximum allowed under NRC
regulations at the time. Thus, the calculations were not intended to be based on realistic or
prudently conservative conditions at POTWs, but based on maximized releases to sewer systems.
The estimates of these hypothetical exposures to workers range from zero to a dose roughly
equal to natural background levels (Kennedy et al. 1992). Table 1.1 summarizes the results for
some of the scenarios considered.
The PNNL study concluded that although concentration of radionuclides in sewage sludge was
likely to occur, more information on the physical and chemical processes was necessary before
reliable quantitative dose estimates could be made. The calculated doses were based on
1 ISCORS is co-chaired by the Environmental Protection Agency (EPA) and the Nuclear Regulatory Commission
(NRC), and ISCORS has representatives from the Department of Defense (DOD), Department of Energy (DOE),
Department of Health and Human Services, Department of Labor, and observers from White House Office of
Management and Budget, the Office of Science and Technology Policy, and various States.
2 Subcommittee members are EPA and NRC (co-chairs) and DoD, DOE, the State of New Jersey, the Middlesex
County Utilities Authority, and the Northeast Ohio Regional Sewer District.
ISCORS Technical Report 2004-03 1-2 Final, February 2005
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estimated rather than measured concentrations of radionuclides. In addition, a relatively small
number of radionuclides were considered.
Table 1.1 Hypothetical Maximum Doses (mrem/year) from PNNL Study
Individual
POTW sludge
process operator
POTW incinerator
operator
POTW heavy
equipment operator
Farmers or
commercial operators
Landfill equipment
operator
Resident on former
landfill site
Exposure Source
Sludge in
processing
equipment
Incinerator ash
Sludge or ash in
truck
Land applied
sludge
Ash disposed in
landfill
Ash disposed in
former landfill
Primary Exposure
Pathway
External
Inhalation of dust
External
Ingestion via local crops,
external
External
Inhalation via resuspension
of dust, ingestion via
garden vegetables
Hypothetical
Maximum Doses
(mrem/yr)
360
340
210
17
64
170
Source: Kennedy etal. 1992.
The State of Washington assessed potential risks to POTW workers, to farmers who spread
sludge on wheat croplands, and to workers at a municipal landfill laying down sludge as cover
material. This study was published as The Presence of Radionuclides in Sewage Sludge and
Their Effect on Human Health (Washington State Department of Health, 1997). The report is
based on sludge samples taken at six POTWs in the State, which were analyzed for
16 radionuclides, total uranium, and gross beta. Two exposure scenarios, involving wheat
farmers and workers at a municipal landfill, incorporated information obtained in interviews
with people who had direct experience in the management and use of sludge in these practices.
The report concluded that doses from radionuclides in sewage sludge are extremely low
compared to background or to generally accepted regulatory dose limits, and that there is no
indication that radioactive materials in biosolids in the State of Washington pose a health risk.
1.3 PURPOSE OF THE PRESENT ASSESSMENT
The purpose of the present assessment is to extend and expand upon work already performed in
evaluating the potential risks to humans posed by radionuclides in sewage sludge and ash. The
assessment described here differs from previous ones in that it uses information obtained in the
ISCORS national survey on radionuclides present in sewage sludge and ash. In addition, the
Final, February 2005
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ISCORS Technical Report 2004-03
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exposure scenarios in this dose estimation are more detailed and comprehensive than those
considered previously.
The information generated here will be used by NRC and EPA to determine if levels typically
occurring in POTW sewage sludge and ash warrant additional testing or further analysis, and if
they are suggestive of the appropriateness of the development of a national regulatory program
to reduce radionuclide levels in sewage sludge, or to control sewage sludge management and the
use of sewage sludge products.
1.4 GENERAL APPROACH
The general approach of the study is a standard one that has been employed elsewhere
(e.g., NCRP 1999). It consists essentially of two steps. First, seven general, fairly generic
scenarios (and some sub-scenarios) are constructed to represent typical situations in which
members of the public or POTW workers are likely to be exposed to sludge. The selection of
radionuclides for consideration was based on the results of the ISCORS survey of sewage sludge
and ash at various POTWs, and includes manmade and naturally-occurring isotopes. Second,
assuming a unit specific activity of a radionuclide in dry sludge, a widely-accepted
multi-pathway environmental transport model (the RESRAD family of codes) is employed to
obtain sludge concentration-to-dose conversion factors (To avoid possible confusion with the
Dose Conversion Factors of the Federal Guidance Reports (FOR 11, FOR 12, and FOR 13), this
study will refer to these computed conversion factors as dose-to-source ratios (DSRs). The
ratios can then be combined with data on radionuclide concentrations in sludge from the sewage
sludge and ash survey to estimate doses for all the scenarios.
The primary output of this assessment is calculated dose-to-source ratios for a number of
radionuclides and a variety of reasonably likely exposure scenarios. A DSR is defined here as
the dose received by a receptor for a unit activity concentration of radionuclide (37 Bq/kg or
1 pCi/g dry weight of sludge/ash), and it is used to convert a known activity concentration in
sludge to a committed Total Effective Dose Equivalent (TEDE)3 by means of the appropriate
RESRAD code. In some cases, additional information on indoor radon and non-radon
components of the radiation dose were also calculated.
1.5 ORGANIZATION OF THIS REPORT
This report provides a complete description of the dose assessment process conducted by the
Dose Modeling Work Group of the Subcommittee. Chapter 2 provides an overview of the
scenarios developed for the assessment and the rationale for the dose modeling approach.
Chapter 3 discusses the sources of radioactive material considered in the dose assessment for
each scenario. Chapter 4 describes each of the scenarios and presents detailed information on
3 In this report, the generic term "dose" refers to "total effective dose equivalent," or "TEDE." The TEDE is
defined as the sum of the effective dose equivalent (EDE) from external radiation and the 50-year committed
effective dose equivalent from internal radiation, and TEDE based on the methodology in ICRP Reports No. 26
and No. 30 (ICRP 1977 and 1979). TEDE is currently the basis of standards and regulations for radiation
exposure in the United States. Background radiation is also generally characterized in terms of TEDE.
ISCORS Technical Report 2004-03 1-4 Final, February 2005
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input parameters used and assumptions made in constructing each scenario. Chapter 5 presents
analyses conducted to assess uncertainty and variability in the scenarios and to identify sensitive
parameters and assumptions. Chapter 6 (with additional detail in Appendix E) presents the
results of the dose assessment: the dose-to-source ratios for each radionuclide in each scenario.
Chapter 7 presents dose calculations combining these dose-to-source ratios with measured
radionuclide concentrations, including some discussion of indoor radon and non-radon
components. Conclusions of this dose assessment are presented Chapter 8, and references are
listed in Chapter 9.
Final, February 2005 1-5 ISCORS Technical Report 2004-03
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2 ASSESSMENT METHODS OVERVIEW
2.1 OUTLINE OF THIS DOSE ASSESSMENT
As noted in the last chapter, seven generic scenarios have been constructed in this study to
represent some of the most likely situations in which workers or members of the general public
might be exposed to sludge. The RESRAD family of codes was then employed to determine, for
each scenario, the peak Total Effective Dose Equivalent (TEDE) to an individual exposed to
sludge that contains a reference quantity of specific activity (1 pCi per gram of dry sludge, or
37 Bq per kg) of each radionuclide of concern. The result is a computed conversion factor,
called the dose-to-sludge ratio (DSR), and there is one for every scenario and for each relevant
radionuclide. Based on the results of the survey and the dose assessment, a decision will be
made on whether additional actions should be initiated to assure protection of public health.
The scenarios were designed to estimate potential radiation doses from exposure of "average
members of the critical group" (i.e., those who may come into contact with municipal sewage
sludge or incinerator ash). The rationale for this approach is based on the charge to ISCORS to
conduct a survey of municipal sewage sludge to determine the extent to which radioactive
contamination of sewage sludge or ash is occurring, possibly causing exposure of people. The
results of the dose assessment tend to be conservative (i.e., estimated doses are probably higher
than actual for each scenario) as a result of choices made by the Dose Modeling Work Group of
this Subcommittee on specific input parameters and assumptions in each scenario, such as the
use of the 95th percentile Dose-to-Source Ratios for calculating doses, and to extend the
modeling out to 1,000 years following application of sludge in an attempt to assure that the peak
dose is obtained.
Because the analysis in this report needs to have general applicability across the range of
conditions across the country, the basic approach of the dose assessment is to model sites in a
generic manner. Because a wide range of variability must be accounted for in a consistent
manner, relatively simple conceptual models are used. There is no attempt to incorporate unique
or heterogeneous environmental pathways that may be present and important at specific sites, so
caution should be employed in applying the results of this analysis to particular sites. A
summary of the limitations of this assessment is presented at the end of this chapter.
2.2 EXPOSURE SCENARIOS
Each hypothetical scenario presented in this assessment consists of a narrative description and a
set of exposure pathways. Guided in part by examples from previous assessments by DOE,
EPA, and NRC, the Work Group developed scenarios that are generic (i.e., not based on the
characteristics of any particular site) but that account for sludge and ash management practices.
The scenarios are intended to represent a variety of different uses or disposal options for sewage
sludge, and situations where radiation exposure is likely. For each, all the standard
environmental transport (resuspension of dust, leaching into groundwater, etc.) and exposure
(external exposure, inhalation, and ingestion) pathways were considered.
Final, February 2005 2-1 ISCORS Technical Report 2004-03
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The seven scenarios created for this assessment fall into four general categories of sludge/ash
management and processing practices. They reflect the observation that most exposure of the
public to sludge results from its land application, disposal in a landfill, or incineration.
Exposures of a worker through proximity to or direct contact with the sludge can occur during
processing, sampling, loading, transport, or application. The scenarios have been designed so
that exposures to the seven following groups may be explored:
1. Residents of houses built on agricultural fields formerly applied with sludge;
2. Recreational users of a park where sludge has been used for land reclamation;
3. Residents of a town near fields upon which sludge has been applied;
4. Neighbors of a landfill that contains sludge and/or ash;
5. Neighbors of a sludge incinerator;
6. Agricultural workers who operate equipment to apply sludge to agricultural lands; and
7. Workers at a POTW involved in sampling, transport, and biosolids loading operations.
Scenarios 1 through 3 consider different kinds of intentional land application of sewage sludge.
For the first two, people are exposed while living on a site of former application, and are said to
be "onsite." The residents of the nearby town, by contrast, are not located at a site where sludge
actually has been or is being applied, but rather are exposed to radionuclides that are transferred
"offsite." Scenarios 4 and 5 treat two other kinds of sewage sludge or ash disposal for which the
exposed populations are also offsite. The distinction is important because dose assessment for
offsite populations is more complex than for onsite, and requires more sophisticated modeling.
The last two scenarios consider possible exposure of agricultural and POTW workers.
2.3 SELECTION OF THE MODEL CODE
Because of the many possible pathways of exposure, a multimedia computer code was selected
for the calculations, according to the following criteria. The model should accommodate the
physical conditions of the scenarios and, in particular, it must
1. Include (or be able to include) all radionuclides of concern;
2. Cover the relevant environmental transport pathways;
3. Include all important exposure pathways;
4. Contain a manageable number of parameters;
5. Incorporate established sensitivity and probabilistic uncertainty analyses;
6. Have undergone extensive verification and peer-review; and
7. Be widely used and accepted, so that the calculations can be readily replicated or
modified.
ISCORS Technical Report 2004-03 2-2 Final, February 2005
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The first three criteria ensure that the essential elements of each scenario's conceptual model are
included. The fourth requires that the numbers of parameters involved are in the hundreds, not
tens of thousands; it is necessary because of resource constraints, but fully justified by the
generic nature of the scenarios. Criterion 5 reflects the preference for using methods that have
previously been developed for sensitivity and uncertainty analyses, rather than developing new
methods; it also makes it possible for outside parties to reproduce the results. Criterion 6 is
needed because, given the complex nature of the assessment, independent verification of every
calculation would be intractable. Finally, the model should be widely available, well
documented, and user friendly for use by interested parties in independent verification of study
analyses and results.
A number of computer models were considered for use in this effort, and Table 2.1 summarizes
how the four finalists compare, according to the seven criteria. The RESRAD family of codes,
including RESRAD version 6.0, RESRAD-BUILD version 3.0, and RESRAD-OFFSITE
version 1.0, was selected largely because of its flexibility in scenario development. It contains
the necessary data on most relevant radionuclides, and can easily accommodate others; it
accounts for all transport and exposure pathways of interest, yet it employs a manageable
number of parameters (about 140 for RESRAD, 300 for RESRAD-OFFSITE, and 40 for
RESRAD-BUILD). In addition, it has built-in sensitivity and probabilistic uncertainty analysis
modules, has undergone more extensive testing than the others, and is widely used within the
remediation community so as to be more familiar than the others to most DOE, DoD, EPA, and
NRC users.
Because Scenarios 1, 2, and 6 involve only onsite receptors, their doses can be estimated with
RESRAD Version 6. Scenarios 3, 4, and 5 are complicated by offsite transport, and hence are
examined with the RESRAD-OFFSITE code (in combination with the CAP88-PC code to
account for airborne transport of radioactive material away from the source). Workers at the
POTW spend nearly all their time indoors, requiring the use of the RESRAD-BUILD code in
Scenario 7. A summary of the scenarios and the model codes used is in Table 2.2.
RESRAD 6.0 and RESRAD-BUILD are simply relatively recent probabilistic versions of
established deterministic codes, but RESRAD OFF-SITE contains newer components, and is
currently still under testing and further development. Experience with RESRAD OFF-SITE has
revealed no substantive problems with it but, in any case, preliminary scoping calculations have
suggested that the magnitude of the off-site doses are relatively very low, so that the status of the
code should not be significant to the final results.
A description of the RESRAD family of codes, including references to how the calculations are
performed, appears in Appendix B.
Final, February 2005 2-3 ISCORS Technical Report 2004-03
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Table 2.1 Comparison of Models
Model Selection Criterion
(1) Radionuclides of concern
(2) Environmental transport pathways
(2.1)Resuspension
(2.2) Groundwater infiltration and transport
(2.3) Surface water run-off (4)
RESRAD
Family™
x(3)
X
X
X
X
PRESTO
CLNCPG
Vers. 4.2
X
X
X
X
X
GENII(2)
Vers. 2.0
X
X
X
X
DandD
Vers. 1.0
X
X
X
X
(3) Exposure pathways
(3.1) External gamma radiation
(3.2) Inhalation of airborne particles outdoors
(3.3) Inhalation of radon (indoors)
(3.4) Inhalation of radon (outdoors)
(3.5) Ingestion of water from a well
(3.6) Ingestion of surface water
(3.7) Ingestion of vegetables, fruits, grains, milk,
and meat produced on treated land
(3.8) Ingestion offish from nearby waters
(3.9) Inadvertent ingestion of soil
(4) Manageable number of parameters
(5) Sensitivity and probabilistic uncertainty analyses
(6) Extensive validation, verification, and peer review
(7) Widely used and accepted
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Notes:
1. In this report, the RESRAD family refers to RESRAD 6. 1, RESRAD-OFFSITE 1.0, and
RESRAD-BUILD 3.0, all of which are available through the RESRAD Website at Argonne National
Laboratory.
2. GENII Version 2.0 runs in the FRAMES environment.
3 . Additional nuclides can be added to RESRAD
4. RESRAD does not include runoff transport, and the on-site scenarios do not account for it. RESRAD
OFF-SITE does incorporate this pathway.
ISCORS Technical Report 2004-03
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Final, February 2005
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Table 2.2 Scenarios and Models in this Assessment
Scenario Exposed
Individual*
Land Application
1 . On site residents on- site
2. Recreational users — on-site
reclamation
3. Residents of nearby town off-site
Landfill Disposal
4. Landfill neighbors — off-site
sub-scenarios for MSW and
impoundment
Incineration
5. POTW incinerator neighbors off-site
Occupational Exposure
6. Agricultural sludge on-site
application worker
7. Indoor POTW worker — on-site
subscenarios for different
POTW operations
Multiple Model Code
Applications
RESRAD Version 6
RESRAD Version 6
RESRAD-OFFSITE/
CAP-88
RESRAD-OFFSITE/
CAP-88
RESRAD-OFFSITE/
CAP-88
RESRAD Version 6
RESRAD-BUILD
Version 3
Note:
* "Site" refers to the area where sludge is originally applied or, for Scenario 7, produced.
2.4 PARAMETER VALUES AND DISTRIBUTIONS
2.4.1 FIXED VALUE AND DISTRIBUTIONS FOR MODELING
PARAMETERS
Each scenario must be translated from a qualitative narrative and a list of potential transport and
exposure pathways into a specific set of parameter values suitable for use in a particular model.
Since probabilistic calculations are needed to assess the uncertainty and variability of the DSR
values quantitatively, distributions are generally appropriate for the most sensitive parameters.
For parameters that are somehow found to be less sensitive, single parameter values may be
used.
Final, February 2005
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ISCORS Technical Report 2004-03
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A fundamental change has recently been occurring in the way radionuclide transport modeling
calculations are carried out. A traditional, so-called deterministic calculation involves the use of
a fixed set of parameter values, and the result is a single curve of dose versus time.
A probabilistic (also known as a stochastic or Monte Carlo) calculation, by contrast, requires the
performance of hundreds or thousands of separate dose computations, each with its own set of
randomly selected parameter values; instead of a single value, a parameter would be represented
by a probability distribution function (or a cumulative distribution function, which contains the
same information but is presented differently) which records the probability (i.e., the relative
frequency) with which a particular value for the parameter will be sampled for inclusion in a run.
Statistical combination of the results from all these runs yields a variety of dose versus time
curves, recording the time dependence of the mean dose, the median dose, or any desired
percentile dose (e.g., the 95-percentile curve, below which the true dose is 95% likely to occur).
In general, probabilistic calculations were employed in this study to determine the evolution of
DSRs, as functions of time, for each scenario and radionuclide. The point DSRs recorded in
Chapter 6 correspond to the peak doses obtained when the calculation is carried out on a steady-
state population over a one-thousand year time span; the time of the peak dose will depend, of
course, on the properties of both the scenario and the radionuclide.
For many parameters, values and distributions were selected that are specific to the scenario at
hand. For others, generic (that is, non-scenario-specific) values and distributions are adequate,
and usually easier to obtain. This is particularly true for plant and animal transfer factors, food
holdup times prior to ingestion, livestock or plant water fractions, soil characteristics, human
behavioral data such as inhalation and ingestion rates under various conditions, and other values
and distributions that are based on national databases and are accepted by regulatory agencies
such as NRC or EPA. Many of these appear as entries in EPA's Exposure Factors Handbook
(EPA 1997) and similar compilations. For a number of standard parameters employed by
RESRAD, generic distributions have recently become available (NRC 2000b); this document,
incidentally, notes that the parameters for which they have provided distributions had been
identified as generally having more influence on calculated dose results than parameters not
included.
Because many of these parameter values and distributions do not change from scenario to
scenario, a set of "baseline" parameter values and distributions have been defined for each
RESRAD code and listed in tabular form in Appendix A. The relatively small number of
scenario-specific parameter values that distinguish the scenarios from one another may thus be
thought of as variations from the baseline, and these are addressed individually in each scenario
description. For baseline parameters for which values or distributions are not available, the
RESRAD default values are used, unless another value is clearly indicated. In all cases, the
default RESRAD values are listed for reference (in parentheses if not used). They are intended
to be as broadly representative as is reasonably achievable, but there may be real situations to
which they do not apply.
ISCORS Technical Report 2004-03 2-6 Final, February 2005
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2.4.2 USE OF DISTRIBUTIONS IN DETERMINISTIC CALCULATIONS
In some cases (in accounting for multiple years of application, as will be discussed below) it is
necessary to perform deterministic calculations in addition to the probabilistic ones. Suitable
average or central-tendency parameter values must then be derived from the distributions. In
deterministic runs, means (arithmetic or geometric) are computed from the distributions to
replace them, as denoted in Appendix A.
2.4.3 PRIORITIES IN PARAMETER SELECTION
To summarize, the justifications for parameter values and probability distributions for input into
the RESRAD family of codes are as follows, in the order of priority:
1. Scenario-description parameter values and distributions
2. Other specified generic parameter values and distributions
3. NRC's NUREG/CR-6697 (NRC 2000b) distributions:
— for probabilistic runs, default distributions
— for deterministic runs, find and use sample means (geometric mean for lognormal
distributions; arithmetic mean for others)
4. RESRAD default values (Yu et al., 2001)
2.5 INTERPRETATION OF RESULTS OF THE PROBABILISTIC
CALCULATIONS
For a particular scenario and for the reference amount of specific activity of some radionuclide,
the probabilistic version of RESRAD carries out J realizations, labeled j = 1, 2, ..., J. That is,
for each j, the Monte Carlo module quasi-randomly selects a value for every RESRAD variable
parameter, where the probability of selection of any particular value is determined by that
parameter's distribution function. RESRAD then computes the dose, dsr^), as a function of
time. The program then searches for the global maximum in dsr^), which we call DSRy, for
every realization. (The maxima in dsr^) is likely to occur at different times for different
realizations, or values of the index j .)
The values of DSRy for the J realizations themselves form a distribution, with a mean, a
95-th percentile value, etc., and these are the DSR-entities tabulated in this report.
2.6 SENSITIVITY, UNCERTAINTY, AND VARIABILITY
The sensitivity analyses in these dose assessments rely to a large extent on previous work in
analyzing parameter sensitivities of the RESRAD codes. For RESRAD and RESRAD-BUILD,
the categorization and ranking of parameter sensitivities are documented in NRC (2000ab).
Additional sensitivity analyses were performed in some cases and is described in Chapter 5.
Final, February 2005 2-7 ISCORS Technical Report 2004-03
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Any modeling contains both quantitative and qualitative uncertainties and variabilities. There
are a number of known, but largely unavoidable, sources of quantitative uncertainty both in the
RESRAD modeling of physical transport and exposure and in the ICRP metabolic determination
of the dose conversion factors that convert intake to committed TEDE. Measurement of a
physical parameter such as soil hydraulic conductivities or an element-specific partition
coefficient will yield a range of values because of normal experimental error and physical
variations among samples. Uncertainty and variability may be addressed to some extent through
the specification of subscenarios within each exposure scenario, or more generally through the
use of sampling of probability distributions for parameter values (e.g., by way of the Latin
Hypercube method).
Qualitative uncertainties and variabilities are those that are known to exist but which cannot be
readily quantified. A significant source of qualitative variability is in the specification of the
exposure scenarios. In the present assessment, these qualitative issues are addressed through
discussions with peer review groups and experts.
A unique source of uncertainty arises in dealing with multiple years of application. RESRAD, in
its current configuration, can carry out a Monte Carlo analysis only for the case of a single
application of sludge. Approximate scaling factors were therefore developed, employing only
deterministic calculations, to handle scenarios with multiple years of agricultural application. It
is acknowledged that this approach, described in the next chapter, introduces an error that
ISCORS believes is small and insignificant to the overall uncertainty.
2.7 ASSESSMENT OF CONTRIBUTIONS FROM INDOOR RADON
PATHWAY
Additional calculations separating radon and non-radon components were performed in cases
where the indoor radon pathway contributed more than 10% of the calculated dose. In these
cases, radon exposure was also calculated in terms of Working-Level units as well as air
concentrations (pCi/L) for the different radon daughters. This separation was done for several
reasons. From the source perspective, indoor radon levels are highly variable and there is
insufficient data to capture the extent of this variability in the probabilistic assessment. In
addition, radon dosimetry is complex, and doses other than TEDE may be more informative.
Finally, indoor radon standards and benchmarks are often based on either Working-Level units
or air concentrations, rather than TEDE.
2.8 LIMITATIONS OF THE CURRENT ASSESSMENT
There are important limitations to this modeling effort, brought about by the need to carry out a
generic assessment across a diverse range of possible situations and environments, by the
insufficiency of parameter information, and by bounds on the capabilities of the models
available. The contributions of some of these to the uncertainties in the assessment results are
discussed in detail in Chapter 5.
ISCORS Technical Report 2004-03 2-8 Final, February 2005
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2.8.1 SOURCES
This assessment evaluates DSRs for the processing, use, or disposal of municipal sewage sludge
and ash. Although more than forty radionuclides were included in this assessment, it is possible
that other radionuclides that are not anticipated to be present in the sewage may exist in the
system. It may not account for all the sources of radiation exposure associated with the
treatment of municipal sewage such as the presence of radionuclides in liquid influent and
effluent. In some cases, POTWs, may use treated effluent as irrigation water on agricultural
lands or other fields. Because the current joint NRC-EPA survey only measured radioactivity in
sludge and ash, dose modeling of radionuclides is limited to only sludge and ash. Nevertheless,
it should be noted that additional radiation exposure from POTW liquid effluent is possible.
2.8.2 SCENARIOS
The scenarios evaluated in this assessment were developed to represent relatively common, real
conditions likely to lead to radiation exposures that are typical, rather than worst case. While it
is possible to consider only a few hypothetical situations, great effort has been made to ensure
that the scenarios considered in this report represent a reasonable range of exposures without
being overly conservative. In certain unique or unusual circumstances, radiation exposure may
be greater.
2.8.3 MODELS
This study utilizes existing models and generalized scenarios which make possible an overall
assessment without having to gather a large amount of site-specific data. There are many
site-specific factors—such as fracture flow, soluble and colloidal transport, the impact of the
POTW sludge de-watering operations on the transport and bioavailability of radionuclides, and
year-to-year and seasonal changes in environmental conditions—that will impact individual
assessments but are not considered or needed here in the general assessment. Thus, the study
includes the average effects of some of these processes in a generic manner, but it has not
attempted to model unique or heterogeneous environmental conditions that may be important at
specific sites. Caution should therefore be exercised in applying the results of this assessment to
individual sites.
Final, February 2005 2-9 ISCORS Technical Report 2004-03
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3 SOURCE ANALYSES AND RELATED ISSUES
This chapter covers two topics. The first is the rationale for the particular set of radionuclides
considered in the dose assessment and the ways in which decay chains are handled. The second
is the determination and preparation for entry into RESRAD of the source terms for the various
scenarios and subscenarios considered.
3.1 RADIONUCLIDES CONSIDERED IN THE DOSE ASSESSMENT
The principal objective of this dose calculation study is to assist in the analysis of the results of
the ISCORS POTW survey and to support the Subcommittee in preparing guidance for POTW
operators. As such, it covers all radionuclides identified in the pilot survey conducted in 1997,
revised in May 1999 (EPA 1999a), and any additional radionuclides found by spectrometry
analysis during the full survey. These radionuclides are listed in Tables 3.1 and 3.2. Information
on daughters for radionuclides included in standard RESRAD is presented by the RESRAD
manual in Tables 3.1 and 3.2 (Yu et al., 2001).
RESRAD distinguishes between "principal" and "associated" progeny in decay chains. A
principal radionuclide is one with a half-life longer than a user-specified cutoff (RESRAD
allows selection of 30 days or one-half year for the cutoff time). In the present assessment, this
cutoff time is selected to be 30 days. An associated radionuclide has a half-life less than the
cutoff; the nuclides "associated" with a principal radionuclide consist of all decay products down
to, but not including, the next principal radionuclide in the chain. This dose assessment assumes
that all associated radionuclides (except radon daughters) remain in secular equilibrium with
their principal radionuclide in the contaminated zone, along transport pathways, and at the
location of human exposure.4
The radiation dose calculated for a radionuclide listed in Table 3.1 includes the contributions
into the future of all the daughter radionuclides (principal and associated) in the decay chain
from decay of the listed nuclide. This assumption ensures that the assessment does not
underestimate the potential impact of that radionuclide. As a naturally occurring radioactive
material in fertilizers and food products, potassium-40 may concentrate in sewage sludge or ash
and, as such, is of concern for this analysis. However, exposure to K-40 is only of potential
concern for external exposures. Internal exposures do not result in increased dose because of the
equilibrium of K-40 in the body. Iodine-131 is included because it is a licensed medical isotope
which is discharged to the sewer system and can contribute to radiation dose, despite its short
half-life.
4 There are many natural and man-made processes which may affect the equilibrium of the nuclides within sludge.
For this reason, for site-specific analyses, the processing method of the sludge and the location and type of sludge
samples collected at the POTW should be known prior to making assumptions concerning equilibrium when
conducting a site-specific dose assessment.
Final, February 2005 3-1 ISCORS Technical Report 2004-03
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Table 3.1 Radionuclides Included in the Dose Assessment
Radio-
nuclide
Ac-227c
Ac-228d
Am-241
Be-7a
Bi-212d
Bi-214d
C-14
Ce-141
Co-57
Co-60
Cr-51a
Cs-134
Cs-137
Eu-154
Fe-59
H-3
1-125
I-131a
In-llla
K-40
La-138a
I-131a
In-llla
Major
Radiations
alpha, beta,
gamma
beta, gamma
alpha, gamma
gamma
alpha, beta,
gamma
beta, gamma
beta
beta, gamma
gamma
beta, gamma
gamma
beta, gamma
beta, gamma
beta, gamma
beta, gamma
beta
gamma
beta, gamma
gamma
beta, gamma
beta, gamma
beta, gamma
gamma
Half-life
22 years
6 hours
432 years
53 days
61 minutes
20 minutes
5,730 years
33 days
271 days
5 years
28 days
2 years
30 years
9 years
45 days
12 years
60 days
8 days
3 days
1.3xio9 years
135xl09 years
8 days
3 days
Radio-
nuclide
Po-210b
Pu-238
Pu-239
Ra-223d
Ra-224d
Ra-226
Ra-228
Rn-219d
Sm-153a
Sr-89
Sr-90
Th-227d
Th-228
Th-229b
Th-230
Th-232
Th-234d
Tl-201a
Tl-202a
Tl-208d
U-233b
Tl-201a
Tl-2023
Major
Radiations
alpha
alpha
alpha
alpha, gamma
alpha, gamma
alpha, gamma
beta
alpha, gamma
beta, gamma
beta
beta
alpha, gamma
alpha, gamma
alpha, gamma
alpha
alpha
beta, gamma
gamma
gamma
beta, gamma
alpha
gamma
gamma
Half-life
138 days
88 years
24xl03 years
1 1 days
4 days
1600 years
6 years
4 seconds
47 hours
51 days
29 years
19 days
2 years
7,340 years
77xl03 years
14xl09 years
24 days
3 days
12 days
3 minutes
158. 5xl03 years
3 days
12 days
ISCORS Technical Report 2004-03
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Final, February 2005
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Table 3.1 Radionuclides Included in the Dose Assessment (continued)
Radio-
nuclide
I-131a
In-llla
K-40
La-138a
Np-237b
Pa-231b
Pa-234md
Pb-210
Pb-212d
Pb-214d
Major
Radiations
beta, gamma
gamma
beta, gamma
beta, gamma
alpha, gamma
alpha, gamma
beta, gamma
beta, gamma
beta, gamma
beta, gamma
Half-life
8 days
3 days
1.3xl09 years
135xl09 years
2.14xl06 years
32.8xl03 years
1 minute
22 years
11 hours
27 minutes
Radio-
nuclide
Tl-201a
Tl-202a
Tl-208d
U-233b
U-234
U-235
U-238
Xe-131md
Zn-65
Major
Radiations
gamma
gamma
beta, gamma
alpha
alpha
alpha, gamma
alpha
gamma
beta, gamma
Half-life
3 days
12 days
3 minutes
158. 5xl03 years
245xl03 years
700xl06 years
4.5xl09 years
12 days
244 days
Source: EPA 1999b.
Notes:
Information on daughters for standard RESRAD radionuclides is included in Tables 3. land 3.2 of theRESRAD
manual (Yuetal., 2001).
a. This radionuclide is not included in standard RESRAD, and it was added as input to the code specifically for
this project.
b. Although this nuclide was not identified in the previous survey (EPA 1999), it is included in the dose
assessment because it is a principal nuclide and its parent nuclide is included in the analysis. Am-241 decays
to Np-237, U-233, and Th-229; U-235 decays to Pa-231; Pb-210 decays to Po-210; and 1-131 decays to
Xe-131m.
c. Although this nuclide was not identified in the previous survey (EPA 1999), it is included in the assessment
because it is the parent nuclide and its daughter nuclides are included in the analysis. Ac-227 is the parent
nuclide of Ra-223, Rn-219, and Th-227.
d. Radiological dose for this radionuclide is included in the dose of its parent nuclide. The parent nuclides are
Ra-228 for Ac-228; Th-228 for Bi-212, Pb-212, Ra-224, and Tl-208; Ra-226 for Bi-214 and Pb-214; U-238
for Pa-234m and Th-234; and Ac-227 for Ra-223, Rn-219, and Th-227.
Several radionuclides that were not identified in the POTW survey have nonetheless been
included in Table 3.1 because they are either a parent or a daughter of a radionuclide that was
analyzed in the survey. These are Ac-227, Np-237, Pa-231, Po-210, Th-229, U-233, and
Xe-131m. Except for Ac-227, which is a parent radionuclide (of Ra-223, Rn-219, and Th-227),
the others are all principal daughter nuclides of which the parent nuclides were detected in the
survey.
Final, February 2005
ISCORS Technical Report 2004-03
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3.2 LAND APPLICATION SCENARIOS
In the Onsite Resident (1), Land Reclamation (2), Nearby Town (3), and Agricultural Worker (6)
scenarios, sludge is applied directly to agricultural or reclamation land and then mixed into the
top fifteen centimeters through tilling and natural processes such as plant root action.
Application may occur a single time or annually for 5 years, 20 years, 50 years, or 100 years.
While very few land application sites in the country are known to have applied sludge annually
for more than 20 years, the 50- and 100-year computations were included primarily for
conssitency with the technical support for EPA's Standards for the Use or Disposal of Sewage
Sludge in 40 CFR Part 503, as a check on the data analysis methodology, and to assist POTW
operators in their consideration of future sludge management practices.
3.2.1 SPECIFIC ACTIVITY IN SOIL-SLUDGE MIXTURE
The activity concentration (i.e., specific activity) of the source term for RESRAD is that of the
soil-sludge mixture, rather than of the sludge alone. The average concentration of a radionuclide
in soil depends on its initial concentration in the sludge, the continuous processes of radionuclide
decay and ingrowth, the amount of sludge deposited per application, the number of prior
(annual) applications that have occurred, the extent of tillage, and other factors. A simple
expression for it assumes that sludge of specific activity ^4sludge [Bq/kg or pCi/g], is applied at a
rate of S [metric tons/hectare], and mixed into the top d [m] of soil that has density r [kg/m3].
The specific activity in soil (Equation 3.la) is then
^Soii = kludge x^/ (d x/0 (3.1a)
for a single land application.
The present dose assessment assumes for its calculations a reference initial specific activity in
dry sludge (1 pCi/g or 37 Bq/kg) of any single radionuclide, and an assumed application rate of
10 metric tons dry sludge matter5 per hectare per year, or 1 kg/m2. (One metric ton is equal to
1,000 kg, and a hectare is 10,000 m2.) Tillage depth is assumed to be 15 cm, and the soil density
5 Annual applications for agricultural utilization are found to range from 2 metric tons/hectare to
70 metric tons/hectare (1 ton/acre to 30 tons/acre), and more typically from 5 to 20 metric tons per hectare-year,
as used in the EPA Part 503 rulemaking assessment. A typical rate is 11 metric tons/hectare (5 tons/acre) per
year, which was rounded to 10 in this dose assessment (EPA 1983, EPA 1995, Sopper 1993). Applying aqueous
sludge mixtures at the same mass rate would result in soil radionuclide concentrations that are lower by the mass
fraction of solids in the aqueous mixture.
ISCORS Technical Report 2004-03 3-4 Final, February 2005
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value of r = 1520 kg/m3 is the mean of the soil density distribution presented in NRC (2000b).6
Inserting these in Equation 3.la yields Equation 3.1b,
Aso]1 = 0.16Bq/kg (0.0044 pCi/g) , (3.1b)
the value used here for direct agricultural application.
Other sludge application rates can be accommodated by appropriately scaling this value. For
instance, since the application rate assumed for land reclamation was greater by a factor of 10,
the resulting initial activity concentration will be 10 times higher or 1.6 Bq/kg (0.044 pCi/g).
3.2.2 MULTIPLE YEARS OF APPLICATION AND WAITING PERIODS
For scenarios that involve multiple years of application, the issue of soil concentration is
complicated by the processes such as decay, ingrowth, and leaching, resulting in the need to
account for the radioactivity added to the soil in previous years' applications in the dose
calculation. The RESRAD code does not include time-dependent source terms, at present, so it
cannot carry out a standard Monte Carlo calculation that involves multiple years of application.
In addition, if there is a waiting period between the application (whether single or multiple) and
the beginning of exposure, the present probabilistic implementation cannot account for this. It is
therefore necessary to develop approximate scaling factors for each scenario, employing only
deterministic calculations, to extrapolate the results for a single year application (obtained with a
probabilistic calculation) into multiple-year application results as well as accounting for any
waiting periods—a process that can be viewed as creating an "effective" source term for the soil
concentration.
To estimate the dose rate resulting from n annual sludge applications, one first carries out a
single-application, probabilistic run at the time of the first application, n = 1, which yields the
dose Z)1prob. In Equation 3.2, this is then scaled for multiple applications by means of a
factor, Fn,
£>/rob = DlptobxFn (3.2)
6 RESRAD can employ a probability distribution for soil density and another for specific activity of contaminated
soil in its calculations, but it cannot, as currently configured, explicitly link the two parameters through a simple
mathematic equation. Several options for dealing with this limitation were considered. It would not be difficult
simply to modify the code to incorporate such an equation, thereby accounting for the dependence of the source's
specific activity on soil density; this, however, would also make it more difficult for outside parties to reproduce
the sludge dose modeling results reported here. Another option would be to employ a correlation between the
final soil concentration and the soil density probabilistically. But this would require significant effort to
determine, confirm, and test the associated correlation coefficient. Furthermore, the algebraic relationship in
Equation 3.1 would not be reproduced exactly by the rank correlation coefficient method used in the Latin
Hypercube algorithm. It was, therefore, decided to fix both the soil density and the specific activity of the
sewage sludge-soil mixture in this assessment. The range of plausible densities for agricultural soils is not that
large, and, in any case, the significance of soil density is examined in the sensitivity analysis.
Final, February 2005 3-5 ISCORS Technical Report 2004-03
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where Fn is defined as the ratio, [Dn Prob//)iProb]j of two doses obtained probabilistically—one
after n annual applications, and the other immediately after a single application, respectively.
But we have no way to calculate Dn prob at present (which, of course, was the problem in the first
place), so we choose to estimate Fn using deterministic calculations in the manner that follows.
The development of the scaling factors themselves is based on the principle of superposition, and
on the assumption of time shift invariance—that is, that the time dependence of the dose caused
by a particular application of sludge depends only on the difference between the time of interest
and the time of application. Then the composite dose from two applications can be obtained by
superimposing that from the second onto that from the first, but with the time of application
shifted. The specific procedure for this process is as follows.
First, the model code is run deterministically for a scenario for a single application at time t = 0.
In this calculation, the Monte Carlo distribution for any parameter is replaced by a corresponding
fixed, averaged value, as described in Section 2.4.2. This run gives the dose D' (t) for any time
in the future from a single application at 7 = 0, where t represents the time difference between
the year of application and the year in which dose is calculated. Thus, if an application
happened during year j, then the dose at year t due to that application would be simply
D-(t-j).
In Equation 3.3a, for a series of n annual applications, the dose at time t would be the sum of
D' (t -j) from 7 = 0 to n -1:
Dn(f) ="D-{t-j) , [7 = 0,... ,w-l] , (3.3a)
where this expression is meaningful only with the constraint (Equation 3.3b)
t • •(»-!) . (3.3b)
Suppose that residents of the property, or the members of any other relevant critical population
group, come into direct or indirect contact with the source r years after the last (the w-th)
application, in year (n - 1 + r). The dose from all applications combined is still given by
Equation 3.4a,
Dn(0 ="D'\t-j) , [7 = 0,... ,«-!] , (3.4a)
but Equation 3.3b is replaced by Equation 3.4b,
f(n-\+r) . (3.4b)
Equations 3.4a and 3.4b are suitable for obtaining Fn, but it is convenient to go one step further.
Let us shift time and rename it from t to tr, defining its origin, tr = 0, as the moment that people
ISCORS Technical Report 2004-03 3-6 Final, February 2005
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first become exposed, so that tr=t-(n-\+r). We also transform the index k = (n - 1 + r) • y,
so that Equations 3. 3 a and 3.3b become
Dn(t,)="D'(tr + k), [k = r,... ,r + n-l] , and tr"Q. (3.5)
With this transformation, k = r represents the dose originating from the most recent application
alone, whereas k = r + n - 1 represents the dose originating from the first application alone. For
the Onsite Resident scenario, where r is set to r = 1, the index k runs from 1 to n. It is
Equation 3.5 that was used to compute the scaling factors for all seven scenarios, with
n=\ year, 5 years, 20 years, 50 years, and 100 years of application.
Because the quantities of interest are the maximum (peak) doses, the scaling factor, Fn, is
defined as the ratio of the peak deterministic doses from n years of application and the basic,
single dose-run in Equation 3.6a,
Fn = max[Dn(tr)] I max[D" (t)] , (3.6a)
or, defining tmcK as the time where D(f) is greatest as in Equation 3.6b, then
Fn = Dn(trmax)/D-(tmax), (3.6b)
where Fn is independent of time.
When re-written so as to account for time, Equation 3.2 then becomes Equation 3.6c,
AT" = A prob x A CO / D' ft. J • (3.6c)
A limitation is that thicknesses of the contaminated zone and unsaturated zone need to remain
unchanged during the time period of interest (tr = 0 years to 1,000 years). The contaminated
zone erosion rate and the groundwater table drop rate were therefore set to zero. The dose
results obtained with these assumptions might be slightly more conservative than without them.
It should also be noted that even if n = 1, the scaling factor may not equal one. In particular, if
there is a waiting period after exposure (r > 0), and the maximum of/)' {f) occurs at t = 0, then
3.2.3 OFFSITE AIR EXPOSURES
Wind can blow contaminated dust from agricultural fields or a landfill where sludge is applied,
or from the stack of a POTW incinerator where it is burned, to an offsite location where people
are actually exposed. This is of importance in the Nearby Town Resident, Landfill Neighbor,
and Incinerator Neighbor Scenarios, and it requires additional analysis of the source term. This
sub-section addresses only the case of dust from a farm field that is transported by the air
Final, February 2005 3-7 ISCORS Technical Report 2004-03
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pathway to a nearby town, 800 m (0.5 miles) downwind, where it settles upon and contaminates
the ground—offsite air exposures for other scenarios will be addressed later.
The assessment consists of three parts—release by the source, transport to the point of exposure,
and deposition and exposure there.
For sludge applied to a field, the source has a release height of 0 meters and a release velocity of
0 m/s, and the dust plume rise is taken to be of the 'momentum' type. The rate of release of
radionuclide from the field is calculated by RESRAD-OFFSITE.
The Gaussian-plume air-dispersion model of CAP88-PC (EPA 1992b) is then run to provide an
estimate for the dispersion factor (• /Q, or "chi over Q"), the ratio that relates air concentration at
a target position downwind, • •(x, y, z, t), to the release rate from the source, Q(t). The
meteorological profile used in the assessment is the annual average data for Columbus, Ohio,
measured from 1988-1992. (The file containing this data is built into CAP88-PC as one of a
number of selectable default options. Columbus was chosen because it has a typical continental
United States wind profile, with a strong predominant wind direction.) The assessment grid
employed here is circular, centered on the source field, and divided into 16 sectors, each of
22.5 degrees circumferential extent. Each sector has 10 radial zones, with their midpoints
800 meters, 1600 meters, 2400 meters, 3200 meters, 4000 meters, 4800 meters, 5600 meters,
6400 meters, 7200 meters, and 8000 meters from the center of the circle.
The dispersion factor at 800 m, and in the direction of maximum • /Q, was found to be
radionuclide dependent, because the deposition velocity and half-life are, as indicated in
Table 3.2.
Table 3.2 Values of Deposition Velocity and Dispersion Factor, */Q, for the
Various Radionuclides, Computed for the Nearby Town Scenario by
CAP88-PC, for Input to RESRAD-OFFSITE
Isotope — Nearby Town
H-3, C-14, Xe-131m, Rn-222
Rn-220
1-125,1-131
All others
Deposition Velocity (m/s)
0
0
0.035
0.002
•tQ (at800m)(s/m3)
7.4xlO~6
2.3xlO~7
8.9xlO~7
6.0xlO~6
Once • /Q has been obtained, RESRAD-OFFSITE accounts for the deposition of airborne
radionuclides to the ground surface at the receptor location. It is assumed that the material
blown from the primary source (field) to the secondary site (Town) is subsequently mixed in
with the top 15 cm of soil in a garden or small field by root-zone action, and is taken up by roots;
it will deposit on leaves, but it contaminates neither groundwater nor surface water.
ISCORS Technical Report 2004-03
Final, February 2005
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With minor modifications, the superposition technique discussed in Section 3.2.2 is used to
assess the time dependence of offsite deposition and exposures from multiple releases of
airborne contaminants.
3.3 LANDFILL/IMPOUNDMENT NEIGHBOR SCENARIO
Two subscenarios were designed for the study of the near-surface burial of sludge and
ash—disposal in a municipal solid waste landfill and in a surface impoundment. In either case,
the source is considered to be 1 hectare (about 2 acres) in area and 2 meters deep.
The source term for the municipal solid waste landfill consists of sewage sludge/ash mixed with
municipal solid waste. The typical composition of municipal solid waste includes about 2.5% of
sewage sludge/ash by weight, thereby creating a dilution factor of approximately 40. Because of
the dominant effect of the non-sludge/ash waste on radionuclide transport, the hydraulic
properties of the source are taken to be those of municipal solid waste (HELP model defaults
from Schroeder et al., 1994), given in Table 3.3 for an activity in sludge of 37 Bq/kg (1 pCi/g).
Table 3.3 Municipal Solid Waste Source Characteristics
Property of Municipal Solid Waste
Activity due to Sewage Sludge/Ash
Saturated Hydraulic Conductivity
Particle Density
Porosity
Bulk Density (derived)
Field Capacity
Value
0.925 Bq/kg
(0.025 pCi/g)
10'3 cm/s
2600 kg/m3 -
- 4700 kg/m3
0.671
860 kg/m3 -
1500 kg/m3
0.292
For a surface impoundment, on the other hand, the source consists entirely of sewage sludge, and
the activity is undiluted. It is assumed that the material degrades biologically relatively rapidly,
and therefore has the hydrologic characteristics of generic soil.
The air emission source for the landfill/surface impoundment is conceptually similar to that of
the agricultural field. Again, the Gaussian plume dispersion model in CAP88-PC is used to
determine the dispersion factor. The ground-level values of • /Q go through a maximum at
150 meters, given in Table 3.4.
Final, February 2005 3-9 ISCORS Technical Report 2004-03
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Table 3.4 Values of Deposition Velocity and Dispersion Factor, */Q, for the
Various Radionuclides, Computed for the Landfill Neighbor Scenario
by CAP88-PC, for Input to RESRAD-OFFSITE
Isotope — Nearby Town
H-3, C-14, Xe-131m, Rn-222
Rn-220
1-125,1-131
All others
Deposition Velocity (m/s)
0
0
0.035
0.002
•tQ (atl50m)(s/m3)
1.7xlO~4
4.8xlO~5
5.1xlO~5
1.6xlO~4
Multiple years of released and deposition are handled in a way similar to that for the Nearby
Town Resident.
3.4 INCINERATOR NEIGHBOR SCENARIO
The source term calculation for the incinerator is in three separate parts. First, the activity per
day of radionuclide vented from the stack for each kilogram of dry sludge burned per day is
calculated, where the sludge is assumed to contain a unit concentration 37 Bq/kg (1 pCi/g) of the
radionuclide. (No decay of the radioactive materials in the sludge occurs prior to incineration.)
Then environmental pathway models (CAP88-PC and RESRAD-OFFSITE) are employed to
determine the concentration in air at the point of exposure for a given value of stack release rate
and, finally, the dose to the neighbor.
The emission source from the incinerator stack is determined by the activity concentration in the
sludge, the feed rate of sludge, and the total control efficiency of the incineration system,
accounting for any stack gas cleaning systems. With activity ^4sludge and feed rate Rfeed, the rate
of radionuclide release from the incinerator stack, RKiease, is given by Equation 3.7,
R
release
(3.7)
where the control efficiency for the radionuclide of interest, CE, is defined as the fraction of the
radionuclide that is not vented as part of the exhaust gas stream. It is generally the quantity
retained by fly ash and bottom ash divided by the total quantity in the feed stream. CE is a
function of the plant design and of the chemical element (different isotopes are assumed to have
the same CE) in question, and of its chemical form, and it can range from 0.0 for noble gases
such as radon to greater than 0.99 for heavy metals such as uranium, thorium, and plutonium.
Further analysis of control efficiencies for sludge incinerators is contained in Appendix C.
Based on the review in Appendix C, control efficiencies, shown in Table 3.5, were developed for
this assessment that provide reasonably conservative estimates of the stack releases.
ISCORS Technical Report 2004-03
3-10
Final, February 2005
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Table 3.5 Incinerator Control Efficiencies, CE, and Release Rates, Rre\ease, for
Various Radionuclides
Isotope
Radon
Carbon
Tritium
Technetium
Iodine
All Other Metals
Control Efficiency
0.0
0.05
0.1
0.1
0.3
0.9
Release Rate
1.76xl08Bq/yr (4.75 x 10'3 Ci/yr)
1.67xl08Bq/yr (4.51 x 10'3 Ci/yr)
1.58xl08Bq/yr (4.27 x 10'3 Ci/yr)
1.58xl08Bq/yr (4.27 x 10'3 Ci/yr)
1.23xl08Bq/yr (3.32 x 10'3 Ci/yr)
1.76xl07Bq/yr (4.75 x 10-4Ci/yr)
A feed rate of Rfeed = 13 metric tons (13 x 103 kg) of dry sludge per day (or 4.75 x 106 kg per
year) is assumed, the value adopted in the technical support document for the sewage sludge
incineration risk assessment for the Part 503 rule (EPA 1992a, Section 5.6.4), and unit-specific
activity of radioactivity A sludge = 37 Bq/kg (1 pCi/g). The release rates, calculated as above, are
also provided in Table 3.5.
The rate of deposition depends on the physical design of the stack. The modeling was based on
data from the Northeast Ohio Regional Sewer District (NEORSD) on the shortest stack for three
of their incineration plants. This stack, which produces the highest ground-level airborne
concentration at a local receptor, is typical of older incinerators. As with the offsite exposure to
agricultural application, the Gaussian Plume air dispersion model in the CAP88-PC code is used
to calculate an activity concentration in the air at various locations as determined by the local
annual average meteorological conditions. The assessment grid is a circular area, centered on
the stack, that is divided into 16 sectors; each sector has eight radial zones, with their midpoints
at 200 meters, 400 meters, 800 meters, 1200 meters, 1600 meters, 2400 meters, 3200 meters, and
4000 meters from the center of the circular assessment area. Since the dose assessment models
the exposure to a member of the critical group who resides at the location of highest • /Q and
who consumes primarily locally grown food, rather than a regional population, a smaller grid
area is appropriate. As before, the meteorological characteristics adopted were the default values
developed from data for Columbus, Ohio.
The point having the highest calculated airborne activity at ground level was found by
CAP88-PC to be 150 meters from the stack. The dispersion factors are provided in Table 3.6.
Final, February 2005
3-11
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Table 3.6 Values of Deposition Velocity and Dispersion Factor, */Q, for the
Various Radionuclides, Computed for the Incinerator Neighbor
Scenario by CAP88-PC, for Input to RESRAD-OFFSITE
Isotope — Nearby Town
H-3, C-14, Xe-131m, Rn-222
Rn-220
1-125,1-131
All others
Deposition Velocity (m/s)
0
0
0.035
0.002
•tQ (atl50m)(s/m3)
1.1 x 1Q-5
5.8 x 1Q-6
1.1 x 1Q-5
1.1 x 1Q-5
RESRAD-OFFSITE code does not calculate "time-integrated" doses, so for the incinerator
scenario, where exposure from shorter lived radionuclides is common, "instantaneous" dose
rates will overestimate the actual annual dose. An adjustment factor (Decay Factor) is used to
account for the decay during the one-year exposure time period. For example, the decay factor
for 1-131 is 0.032, while for long-lived radionuclides, the decay factor is 1. The decay factors
are given in Table 3.7 below.
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3-12
Final, February 2005
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Table 3.7 Decay Factor Adjustments for Incinerator Neighbor Scenario
Radionuclide
Ac-227
Am-241
Be-7
C-14
Ce-141
Co-57
Co-60
Cr-51
Cs-134
Cs-137
Eu-154
Fe-59
H-3
1-125
1-131
In-111
K-40
La-138
Np-237
Pa-231
Decay Factor for
1 year
0.98
1.00
0.21
1.00
0.13
0.65
0.93
0.11
0.85
0.99
0.96
0.99
0.97
0.23
0.032
0.012
1.00
1.00
1.00
1.00
Radionuclide
Po-210
Pu-238
Pu-239
Ra-226
Ra-228
Sm-153
Sr-89
Sr-90
Th-228
Th-229
Th-230
Th-232
Tl-201
Tl-202
U-233
U-234
U-235
U-238
Xe-131m
Zn-65
Decay Factor
for 1 year
0.46
1.00
1.00
1.00
0.94
0.0077
0.20
0.99
0.85
1.00
1.00
1.00
0.012
0.047
1.00
1.00
1.00
1.00
0.047
0.62
Final, February 2005
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3.5 SLUDGE/ASH MANAGEMENT SCENARIOS
3.5.1 SLUDGE APPLICATION WORKER SOURCE
The sources of exposure to a worker who is applying sewage sludge to a field will be the field
itself and, to a lesser extent, the sewage sludge on the truck. The field will contain radioactivity
applied not only this year, but also in prior years. The sludge applied is assumed to be dry, dusty
material. Exposures will occur primarily through direct gamma irradiation, which is reduced but
not fully eliminated by the shielding the truck provides, and the inhalation of dust.
In view of the variability in procedures and type of equipment used, and the complexity of dose
contributions coming from past applications as well as from the current one, it is necessary to
simplify aspects of the problem. The cab of the truck is assumed to be simply a box. The sludge
application rate and tilling depth are the same as for the onsite resident. Rather than performing
a time-integral as the truck traverses the field in a raster or spiral patter, the driver is located at
the center of the full field; both external and inhalation doses would come mainly from the
immediate vicinity of the truck, and change little from place to place within the field—so the
dose would almost entirely be determined only by the time the driver spends working there.
3.5.2 PUBLICLY OWNED TREATMENT WORKS WORKER SOURCE
POTW operations are complex, and some readers may find a brief description of them to be
helpful. A POTW is a facility that takes in water-borne raw sewage for proper treatment. There
are two resulting products: (1) treated effluent water, which typically is released into nearby
surface waters, and (2) sewage sludge, which will be processed to a certain degree to meet
Federal and/or State regulatory requirements and to be beneficially used or properly disposed.
Because of the large volume of water being managed by the POTW, dilution will result in any
radioactivity in the influent sewage first entering the POTW to be of very low concentration. As
a result of the various physical, chemical, and biological treatment processes, however, a certain
amount of radioactivity may become concentrated in the sewage sludge and thereby be removed
from the wastewater, so that the levels of radioactivity present in the final treated effluent water
will be even lower. For this reason, the concern for POTW workers centers on operations that
require workers to be in close proximity to sludge or ash so as to be directly exposed to the
radioactivity in sewage sludge or ash.
Solid materials are initially removed from sewage sludge. The wastewater passes through a
series of treatment processes separating solids, removing certain dissolved materials, and
destroying certain organic materials in the water. Sludge is formed by means of sedimentation
of inert and non-organic matter in the primary treatment and by settling within basins
("clarifiers") or lagoons. When removed from the bottoms of sediment tanks, clarifiers, or
lagoons, the sludge is still mainly water, containing as little as 0.5% solids. This material is
commonly piped to a digester for stabilization and sometimes may be treated with lime. The
resulting sludge is around 5% solids. Often it is then hauled to nearby farmland and land-applied
as a liquid material. Alternatively, after this thickening it is sent by pipes or conveyers to a
ISCORS Technical Report 2004-03 3-14 Final, February 2005
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drying bed, mechanical de-watering devices (belt presses or centrifuges), and/or thermal
de-watering devices. The resulting produces may be"sludge cake," usually 15% to 20% solids,
or dry sludge with even higher solids contents.
Much sewage sludge is used directly in sludge cake form, sent to a truck via a conveyor system,
and shipped to the fields. Some sewage sludge may be held in a composting area for certain
periods of time for pathogen control.7 In Metro., it states that sewage sludge which is dealt with
in this manner meets the 40 CFR Part 503 Rule Class B pathogen requirements and is routinely
used as a fertilizer and soil amendment in ranching, forestry, and land reclamation projects
(Metro 2000).
Some POTWs may follow digestion and de-watering with biosolids processing, depending on
the intended end use or disposal of the final product. The sewage sludge may be processed to a
high level and sold as a relatively dry soil conditioner with solids content of 50%-95%
(e.g., compost) or as a fertilizer (generally pelletized) product for application to fields, lawns, or
parkland. In these cases, the sludge may undergo additional treatments, such as drying, mixing
with other materials, or other modifications, during any of which there may occur worker
exposure.
For POTW operations, three different worker exposure subscenarios have been designed,
involving the sampling, processing, and loading of biosolids. For the first of these, the worker
obtains and carries a 1-liter sample containing 95% water and 5% sludge solids by volume, with
a sludge dry weight of about 0.075 kg (.165 Ibs) (assuming sludge solids have a density of about
1.5 g/cm3). Thus a sludge sample with unit activity concentration of 37 Bq/kg (1 pCi/g) will
contain 2.8 Bq (75 pCi) of activity, and is considered a point source in this assessment.
For sludge processing, the worker stands near a conveyer belt carrying 10 liters/meter of unit
concentration sludge at 20% solids. The source is thus considered a line source with 111 Bq/m
(3000 pCi/m).
For biosolids loading, the worker carries out tasks near a circular pile of de-watered sludge
(porosity of 0.4 and dry bulk density 1520 kg/m3) that is 100 m2 (.0247 acres) in area and 0.5 m
(1.64 ft) in thickness. Again, a unit activity concentration of 37 Bq/kg (1 pCi/g) is assumed.
7 Sludge that is composted ends up typically in the range of 40%-60% solids, and it is much like an organic
topsoil. This material can dry out further, but when placed in piles, the surface tends to seal over. The inner pile
material retains much of its moisture, so that the entire pile does not turn to dust.
Final, February 2005 3-15 ISCORS Technical Report 2004-03
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4 EXPOSURE SCENARIOS
This chapter describes in detail the exposure scenarios of the study. Each assessment starts with
the selection of a specific set of parameter values and distributions to be used as inputs to the
RESRAD family of codes. The RESRAD code employed for each scenario is listed in
Chapter 2 along with the individuals considered to be exposed. In the following subsections, a
table is provided for each scenario, indicating the exposure pathways considered to be active. A
second table delineates those modeling parameters that differ from the baseline values listed in
Appendix A.
A specific choice of modeling parameter values and distributions for a scenario reflects and
defines the characteristics of the site and of the exposed population. It also largely establishes
the degree of conservativeness of the calculation. For this study, an attempt was made to
construct scenarios to yield doses to "the average members of the critical group." Here, the
"critical group" for a scenario refers to a sub-population with relatively high exposure to sludge
through close proximity or through the management practices described in the scenario. The
"average member" of the critical group is then defined by the pathway and the rate of exposure
to sludge-related radionuclides, based on average, or typical, conditions for the group. That is,
the environmental conditions and the behavior, and thus the rate of exposure, of the average
member of the critical group are intended to be plausibly conservative and not extreme-cases.
As noted earlier, most parameter values and distributions do not change from scenario to
scenario. A set of "baseline" parameter values and distributions has been defined, and these are
listed in Appendix A. The majority of these coincide with RESRAD default values, the
justification for which are explained in the RESRAD documentation. The relatively small
number of parameter values and distributions that are scenario-specific are explicitly listed and
discussed in each scenario description. For some of these, appropriate and credible references
led to the choice of particular parameter values or distributions; in other cases, the selection
resulted from discussions (sometimes lengthy) among the Work Group members and their
consultants. Because the scenarios have been devised to serve as generic sites rather than to
describe specific ones in detail, there are bound to be real situations to which they do not apply.
They are intended, however, to be as broadly representative as is reasonably achievable.
4.1 ONSITE RESIDENT
In risk assessment, the resident farmer family is often modeled as a bounding case study. A
similar but much more common situation, however, is that of people who inhabit homes built on
land previously used for farming—new houses are often constructed on former farmlands near
urban areas. In both scenarios, the exposure pathways are essentially the same. Because this is a
common trend in the United States, this Onsite Resident is the first and the most extensively
explored scenario out of the seven considered.
In this scenario, the source farm-field was amended one or more times in the past with sewage
sludge fertilizer that may have contained radionuclides, as discussed in Chapter 3. A house was
completed on the land one year after the last deposition of sludge, and thereafter it is inhabited
Final, February 2005 4-1 ISCORS Technical Report 2004-03
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by people who are not professional farmers. It is conservatively assumed that they produce
significant portions of their annual diet on-site in the same manner as the resident farmer.
Radionuclide transport did occur over the year(s) before the new residents came onsite and
continues after they arrive.
The relevant transport and exposure pathways assumed for this scenario are summarized in
Table 4.la. Family members are exposed directly to external gamma emissions from
sludge-containing soil. They inhale resuspended dust and outdoor radon and, since the home is
built on land where sludge has been applied in the past, indoor radon as well. Doses from indoor
radon can vary greatly depending on the construction of a building's foundation. For residential
homes, the three major foundation types for new construction are an enclosed crawl space, a
slab, and a basement. A simple slab-on-grade without excavation of the upper soil layer was
modeled in this assessment, since preliminary RESRAD calculations indicated that this allows
more radon diffusion into the house than the basement. The RESRAD code was not designed to
evaluate an enclosed crawl space foundation type, but it is plausible that (with a nearly airtight
crawl space) radon concentrations might be higher in such a situation because of a "chimney"
effect. In most situations, however, the crawl space is not airtight, so little radon is likely to
move into the house. As for the basement, there would be a much lower concentration under and
around the house post-excavation than for a slab construction house. In real houses, of course,
radon concentration depends strongly on the specifics of the design and construction, but that
level of detail is neither practicable nor appropriate for the generic scenario modeled here.
With respect to the ingestion pathways, the residents drink well water, and grow vegetables
(50%), fruit (50%), and fodder (100%), and raise a few animals for personal consumption
(100% of meat and milk), and they may inadvertently ingest small amounts of soil. It is assumed
that 90% of the drinking water for humans comes from a well located at the down-gradient edge
of the source field, and about 10% from uncontaminated sources (e.g., from a nearby town's
treated waterworks) consumed while the resident is away from the property. Human ingestion of
contaminated surface water was considered to be unlikely, given the availability of well water,
but there may be exposure through fish caught from a local river or lake; fifty percent of the
annual diet offish is from contaminated surface water. The food produced onsite is grown in
soil that has been treated with sludge and that is irrigated with groundwater and surface water
that contains radionuclides washed out of the sludge/soil mix. The soil ingestion pathway is
included, but a pica child who exhibits excessive hand-mouth activity or deliberate consumption
of soil is not considered. These ingestion assumptions are generally conservative.
Table 4.1b lists those parameter values or distributions that differ, for the Onsite Resident, from
the baseline, as indicated in Tables A.7, A.9, and A.I 1 of Appendix A. In nearly all cases (with
the exception of the POTW Workers), the baseline was set specifically for the Onsite Resident,
so almost no entries are needed in Table 4. Ib.
The interpretation of some of the parameter entries in Appendix A requires a thorough
knowledge of RESRAD. Consider, for example, the assertion that 50% of leafy vegetables are
grown onsite. The baseline vegetable consumption value and distribution are presented in
Table A.7 in the subsection labeled Ingestion Pathway Dietary Data. The RESRAD Default
Value of -1 under Contaminated Fractions instructs the model to base its selection on the size of
ISCORS Technical Report 2004-03 4-2 Final, February 2005
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the site; for the Onsite Resident site, with a baseline area of 404,685 m2, the -1 flag leads
RESRAD to accept a contaminated fraction for vegetables, fruits and grains (or, equivalently,
the fraction of consumed vegetables, fruits and grains that are produced onsite) of 50%.
Likewise, the Contaminated Fractions for fodder, meat and milk are 100%. While 100% for
these last two may seem high, it was determined that cutting them significantly, such as in half,
would lead to a very small change in the DSRs in nearly all cases — so the RESRAD default
values have been retained. There are a few radionuclides that are exceptions, in which the meat
pathway contributes more then 30% to the total dose; these include Sr-89 and Sr-90 (-55%),
1-125 (-80%), Pb-210 (-70%), Po-210 (-90%), U-233, U-234, and U-238 (-55%), and Zn-65
(-30%). No radionuclides contribute more than 15% to the milk pathway.
Six sub-scenarios are used to investigate the dependence of calculated dose on the number of
years of application of sludge, given in Table 4. Ib. The first sub-scenario performs a complete
probabilistic analysis for one year of application, making use of all the currently available
parameter distributions and sampling capability of RESRAD Version 6, apart from field size.
Sub-scenario two also considers only a single application, but it is fully deterministic; it serves
as a baseline for the deterministic computations for multiple years of application (as discussed in
Section 3.2.2) that follow. Sub-scenarios three through six use deterministic calculations to
examine the impacts of five, twenty, fifty, and one hundred years of accumulation of sludge
onsite, respectively. While very few land application sites in the country are known to have
applied sludge annually for more than 20 years, the 50- and 100-year computations were
included primarily for consistency with the technical support for EPA's Standards for the Use or
Disposal of Sewage Sludge at 40 CFR 503, as a check on the data analysis methodology, and to
assist POTW operators in their consideration of future sludge management practices. As
discussed in connection with Equations 3.6a and 3.6b, the factor Fn (the ratio of the w-year
deterministic to the 1-year deterministic doses) is used to scale the single-year probabilistic
results of sub-scenario 1 for multiple years of application.
The level of detail in Table 4. Ib (the assumptions on site water versus town water, on well water
versus surface water, etc.) appears to be much less than that in Table 4. la only because nearly all
the information in the latter is already incorporated into the set of baseline RESRAD parameter
values for this study, as summarized in Appendix A.
Final, February 2005 4-3 ISCORS Technical Report 2004-03
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Table 4.1 a Onsite Resident Scenario Pathways
Human
Exposure
External radiation
Inhalation
Ingestion of water
Ingestion of
plants
Ingestion of
meat / milk
Ingestion of fish
Ingestion of soil
Environmental
Direct exposure
Resuspended dust
Indoor radon
Outdoor radon
Groundwater
Surface water
Irrigation water
Dust Deposition
Root uptake
Livestock water
Livestock soil
Fodder
Surface
Irrigation
water
Dust
deposition
Root
uptake
Surface soil
Pathway
Included?
Yes
Yes
Yes
Yes
Yes
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Comments
Agricultural field; soil / sludge mixture 15 cm
deep
Mass loading represents an average value; dust
from top 15 cm (mixture region)
House sits on contaminated zone surface;
diffusion in through slab foundation; exchange
with outdoor air; radon also from water.
Radium in contaminated soil
90% ingested water from onsite well,
10% from uncontaminated sources
People with wells generally do not drink
surface water.
50% from well, 50% from surface waters
Plants contaminated through foliar deposition
of dust.
Plants contaminated through root uptake.
50% from well, 50% from surface waters
Soil consumption by livestock
Root uptake of, and foliar deposition of,
contaminated water. Water 50% from well,
50% from surface waters.
Foliar deposition of dust
Root uptake from contaminated soil
Consumption offish from contaminated
surface water
Dirt from hands, etc. Pica child not
considered.
ISCORS Technical Report 2004-03
4-4
Final, February 2005
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Table 4.1 b Onsite Resident Scenario and Sub-Scenario Parameters and
Distributions
Subscenario
1
(Uncertainty)
1
2-6
(Deterministic)
All
All
2
3
4
5
6
Parameter
Years of application
Log or linear
spacing
No. of graphic
points
Years of application
Years of application
Years of application
Years of application
Years of application
Value/Distribution
Appendix A Baseline
distributions, values,
except...
1
Appendix A Baseline
values, except...
Linear
1024
1
5
20
50
100
Comments
Probabilistic, except
land area
All other parameter
values and distributions
are baseline from
Table A.7.
Deterministic
So as to obtain annual
dose results for each
year
Maximum permitted by
RESRAD. Data from
graphical points (one at
each year from 0 to
1023) are used to
calculate scaling
factors.
Replace distributions
with point values (see
Sections 2.4.2, 3.2.2)
II
"
II
II
4.2 RECREATIONAL USER ON RECLAIMED LAND SCENARIO
The Recreational User scenario takes place on a land reclamation site where there occurred a
single large application of sludge which is incorporated into the soil to help reclaim an area
disturbed severely by mining or excavation. It is a common practice, where possible, to attempt
to incorporate the sludge and other soil additives, such as agricultural lime, manure, etc., into the
surface material of the reclamation site by discing or other tillage practices. This helps to
Final, February 2005
4-5
ISCORS Technical Report 2004-03
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prepare the area to support the establishment of a sustainable vegetative cover. Typically, no
separate cover is applied in such treatment.
It will take some time before trees and other plants establish themselves and animals come to
inhabit the site. The present analysis assumes that three years after sludge application, when a
sustainable vegetative cover is in place (and after short-lived isotopes have largely decayed
away), the site is opened to the general public for hiking, camping, picnicking, boating, hunting,
fishing, and other residential uses. No residential homes are constructed, nor is there any
agriculture.
Of the various recreational users, the hunter-fisherman who consumes game and fish obtained
onsite is likely to be the most highly exposed. Recreational users are assumed to spend one
week per year outdoors in the area. (The doses from all exposure pathways except game meat
consumption can be scaled linearly to account for shorter, longer, or multiple visits.) Game such
as deer will eat plants that may have extracted radionuclides from the soil, and they will drink
potentially contaminated surface waters. A hunter kills a single deer (typically the legal limit);
he eats a portion of it over the course of the following year. Likewise, fish will take up
radionuclides that reach surface waters; but unlike the situation for deer meat, it is assumed that
nearly all fish caught are eaten onsite.
Also included in the modeling are external exposure, inhalation of contaminated dust, and soil
ingestion. The source and availability of water will vary from place to place. Some sites will
have wells for drinking water and washing, while at others, users may have to rely on surface
water. It is assumed here that people drink from a well, and wildlife drink surface water. The
exposure pathways are summarized in Table 4.2a, and parameter distributions and values
specific to this scenario (i.e., those that are not baseline) appear in Table 4.2b. Also not listed in
Table 4.2b are those values that explicitly apply to indoor activities, or to irrigation, or to the
consumption by humans of surface water, fruit, grain, leafy vegetables, or milk obtained onsite
(since these pathways are considered to be not in operation). In cases where a pathway has been
turned off in the model, some parameters have been left at their baseline values—which, of
course, has no effect on the dose calculation.
ISCORS Technical Report 2004-03 4-6 Final, February 2005
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Table 4.2a Recreational User on Reclaimed Land Pathways
Human
Exposure
External
radiation
Inhalation
Ingestion of
water
Ingestion of
plants
Ingestion of
meat / milk
Ingestion of
fish
Ingestion of
soil
Environmental Pathway
Direct exposure
Resuspended dust
Indoor radon
Outdoor radon
Groundwater
Surface water
Irrigation
water
Dust deposition
Root uptake
Livestock
Livestock
Fodder
(game) water
(game) soil
Irrigation water
Dust deposition
Root uptake
Surface water
Surface soil
Pathway
Included?
Yes
Yes
No
Yes
Yes
No
No
No
No
Yes
Yes
No
Yes
Yes
Yes
Yes
Comments
All well water
No farming, irrigation
Deer drink surface water.
No irrigation
Vegetation for deer grows in
contaminated soil.
Final, February 2005
4-7
ISCORS Technical Report 2004-03
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Table 4.2b Recreational User Scenario Parameters and Distributions
Parameter
Livestock (i.e., deer)
water contamination
fraction
Plant food contamination
fraction
Meat (deer)
contamination fraction
Aquatic food
contaminated fraction
Livestock fodder intake
for meat (kg/d)
Livestock water intake
for meat (L/d)
Livestock intake of soil
(kg/d)
Groundwater fraction for
livestock water
Storage time for meat (d)
Storage time for fish (d)
Meat transfer factor
(pCi/kg perpCi/d)
Value/Distributions
1
0
1
1
2.7 kg/d
7 L/d
0.02
0
182.5
0
Baseline values
Comments
From Wildlife Exposure Factors
Handbook (EPA 1993b), Allometric
Equations for herbivore mammals for a
250 Ib (~1 14 kg) deer (Whitetail deer
from Nebraska Game and Parks
Commission)
From (EPA 1993b) Allometric Equations
Deer prefer leafy plants. Value obtained
by scaling the Baseline rate of ingestion
of grass by a cow. Assume all vegetation
eaten onsite.
Deer drink only surface water.
Deer meat consumed over 365 d.
Fish eaten right away.
Use cattle values and distributions as was
done in the Part 503 rule.
ISCORS Technical Report 2004-03
4-8
Final, February 2005
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4.3 NEARBY TOWN RESIDENT SCENARIO
The Nearby Town Resident scenario is designed to assess the doses to members of the public
living in a town, the proximal edge (and critical group) of which is located about 800 m
(0.5 mile) downstream (for both ground- and surface-water) and downwind from an agricultural
field where sludge has been applied for one or more years. None of the receptor population
resides on the site where sludge was applied, nor do the local people eat a significant amount of
food grown there, so that all exposure pathways involve physical transport of radionuclides from
the source field to the town or to neighboring fields. (Dust that settles on other fields and affects
crops there—or is then resuspended and blows into the town—is assumed to be of much less
consequence than dust from the primary field.)
Primary pathways include airborne transport of contaminated dust from the source field either to
the town or to other fields, and runoff of contaminated soil into a lake or river that supplies water
for the town and neighboring farms. Another possibly important pathway is leaching of
radionuclides into the groundwater and into the surface water. Townspeople may inhale dust
blown from the sludge-applied field, or be exposed to dust that has settled on the streets or other
areas of the town, or drink contaminated water from local wells or from nearby surface water, or
ingest plants grown in nearby fields that are contaminated by the airborne dust, etc. A body of
surface water is available for fishing. It is located midway between the sludge-applied field and
the receptor, and can be contaminated by groundwater flowing from the primary site.
All of these mechanisms involve dilution of the source material prior to exposure of the Nearby
Town Residents or of nearby farms (where food is produced for local consumption), and it was
expected that this scenario would yield dose values much lower than those of the Onsite
Resident. The possibility of more than a few people being exposed, however, does add
relevance to the case.
Exposure pathways for the Nearby Town scenario are described in Table 4.3a, and the
non-baseline parameters are described in Table 4.3b.
Final, February 2005 4-9 ISCORS Technical Report 2004-03
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Table 4.3a Nearby Town Resident Pathways
Human
Exposure
External
radiation
Inhalation
Ingestion
of water
Ingestion
of plants
Ingestion
of
meat/ milk
Ingestion
offish
Ingestion
of soil
Environmental
Pathway
Direct exposure
Suspended dust
Indoor radon
Outdoor radon
Groundwater
Surface water
Irrigation water
Dust deposition
Root uptake
Livestock
Livestock
Fodder
water
soil
Irrigation
water
Dust
deposition
Root
uptake
Surface water
Surface soil
Pathway
Included?
Yes
Yes
No
Yes
No
No
No
Yes
Yes
No
Yes
No
Yes
Yes
Yes
Yes
Comments
Contamination of surface soil in town;
dust deposited by airborne transport from
the field
Atmospheric transport from
contaminated field
Diffusion of radon into basements from
surrounding soil; nearly all radon
entering basements will be from native,
local soil, not from sludge.
Air transport and radon emanation from
deposition of contaminated dust
Town uses treated and monitored water,
so actual radionuclide content would not
exceed MCLs.
Town uses treated and monitored water.
Town uses treated and monitored water.
Root uptake from soil contaminated by
atmospheric transport.
Town uses treated and monitored water.
Town uses treated and monitored water.
Atmospheric transport from
contaminated agricultural field.
ISCORS Technical Report 2004-03
4-10
Final, February 2005
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Table 4.3b Nearby Town Resident Scenario and Sub-Scenario Parameters and
Distributions
Subscenario
1
(Uncertainty)
1
2-6
(Deterministic)
all
all
2
3
4
5
6
Parameter
Years of application
Fraction of water from
surface body
- Household purposes
- Beef cattle
- Dairy cows
- Irrigation for fruit, grain,
non-leafy vegetable field
- Irrigation for leafy
vegetable field
- Irrigation for livestock
pasture and silage field
- Irrigation for livestock
grain field
Fraction of water from well
c/Q, all
Number of intermediate time
points
Times at which output is
reported
Years of application
Years of application
Years of application
Years of application
Years of application
Value/Distribution
Appendix A baseline
values and
distributions, except...
lyr
0
0
0
0
0
0
0
0
0
see Table 3.2
Appendix A baseline
and Subscenario 1
values, except...
1024
1023
lyr
5 yrs
20yrs
50 yrs
100 yrs
Comments
Household water and
irrigation water are not
contaminated. They are
not from a local well or
surface water body.
Household water and
irrigation water are not
contaminated
To obtain annual dose
results for the considered
time frame of 1000 years.
To obtain annual dose
results for the considered
time frame of 1000 years
NA
NA
NA
Final, February 2005
4-11
ISCORS Technical Report 2004-03
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4.4 LANDFILL/SURFACE IMPOUNDMENT NEIGHBOR SCENARIO
In two sub-scenarios, people live in a house near (150 meters) the boundary of either
(a) a municipal solid waste (MSW) landfill or (b) a surface impoundment where sewage sludge
or ash is buried. Source characteristics were discussed in Section 3.3.
While not professional farmers, the landfill neighbors do some gardening and raise a few animals
for personal consumption. The landfill or impoundment is fenced in, and neither the neighbors
nor any animals spend any time on it.8
Each of these sub-scenario extends over three distinct time-periods, during which the site is
(1) being filled with sludge and waste, (2) being monitored after filling is complete (required to
be 30 years under RCRA regulations), and (3) past the 30-year monitoring period.
1. The time of active landfill operation is relatively short. It is assumed that a liner prevents
contaminants from leaching into the ground water9 (i.e., the leachate is captured, treated and
released) and that groundwater is monitored. The sludge is presumed to be moist, moreover,
with little suspension of dust. The fact that the sludge sits primarily below grade keeps the
direct gamma exposure of any neighbors low.
2. Over the subsequent 30 years, the liner remains intact or is repaired if leakage is detected, and
an engineering barrier (i.e., an impermeable cover) prevents contaminant runoff into
neighboring surface waters or airborne releases. Decay and ingrowth are accounted for in the
model, but there are no active pathways by means of which radioactive material can expose
people.
3. Only the third period need be analyzed in this scenario. For simplicity, it is assumed that the
cover is a relatively impermeable clay and that the liner is a compacted clay (i.e., drainage
layers and geo-membranes are not used), with standard default properties.
In both sub-scenarios, the cover thickness and erosion rate have default values, so that cover
breakthrough occurs halfway through the 1,000-year calculation period. The integrity of the
cover and liner would determine the water infiltration rate to deeper soil, but no actual data are
available to correlate the integrity condition with the infiltration rate. Previous data on
RCRA-D leak detection systems show an infiltration rate ranging from 0.004 cm/yr to 16 cm/yr
(0.0016 in./yr to 6.3 in./yr), with a typical value of 0.9 cm/yr (0.35 in./yr). Preliminary analyses
using the HELP model showed that the infiltration rate can range from 3.3 cm/yr (1.3 in./yr) for
a conservative case to 22 cm/yr (8.7 in./yr) for a very worst case, so a value of 3.3 cm/yr
(1.3 in./yr) was used for the deterministic calculations. For the uncertainty calculation, the
8 Someone building a residence directly on a landfill far in the future might well experience a higher dose than
someone living near it, but many states have laws prohibiting such an intrusion; even without such institutional
control, moreover, deeds should record that a landfill once occupied the site, making construction there unlikely.
The landfill neighbor scenario would thus seem to be more plausible and realistic than that of the intruder.
9 Typical leakage rates through RCRA D landfills have been measured to be about 1 cm/yr, which is considered
negligible in the context of this generic assessment.
ISCORS Technical Report 2004-03 4-12 Final, February 2005
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infiltration rate was assumed to have a uniform distribution with a range of from 3.3 cm/yr
to 22 cm/yr (1.3 in./yr to 8.7 in./yr).
The value of the runoff coefficient, which determines the relative amount of precipitation that
flows off-site, was tailored to the selected infiltration rate, with a range of from 0.413 to
0.916 chosen. To avoid a situation in which the infiltration rate would be greater than the soil
hydraulic conductivity, the hydraulic conductivity of the liner was set equal to the infiltration
rate value, and was correlated with the runoff coefficient in the uncertainty calculation.
The other specific pathways and parameters, which are similar to those of the Onsite Resident
scenario, are shown in Tables 4.4a and 4.4b.
Final, February 2005 4-13 ISCORS Technical Report 2004-03
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Table 4.4a Landfill Neighbor Pathways—Post-Monitoring Period
Human
Exposure
External
radiation
Inhalation
Ingestion of
water
Ingestion of
plants
Ingestion of
meat / milk
Ingestion of
fish
Ingestion of
soil
Environmental Pathway
Direct exposure
Suspended dust
Indoor radon
Outdoor radon
Groundwater
Surface water
Irrigation water
Dust deposition
Root uptake
Livestock water
Livestock soil
Irrigation water
Fodder ,
Dust deposition
Root uptake
Surface water
Surface soil
Pathway
Included?
Yes
Yes
No
Yes
Yes
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Comments
Cover has been eroded/disturbed.
House is not on sludge disposal
site.
Cover has been eroded /disturbed.
90% ingested water from well,
10% from uncontaminated sources
50% from well, 50% from surface
waters, foliar deposition of water
Mainly from air dispersion of the
sludge material
Soil becomes contaminated
because of deposition of
radionuclides resulting from air
dispersion and irrigation.
50% from well, 50% from surface
waters
50% from well, 50% from surface
waters, root uptake
Surface water becomes
contaminated through runoff of
radionuclides from the landfill.
ISCORS Technical Report 2004-03
4-14
Final, February 2005
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Table 4.4b Landfill Neighbor Scenario Parameter and
Distributions—Post-Monitoring Period
Parameter
Value / Distribution
Comments
Appendix A baseline values and distributions, except...
Nuclide concentration (pCi/g)
Primary Contamination Area
Parameters
Area of primary contamination
(m2)
Length of contamination parallel
to aquifer flow (m)
Depth of soil mixing layer (m)
Runoff coefficient
Irrigation applied per year (m/yr)
Decay /ingrowth for 30 years
Initial activity:
Subscenarios 1 & 2 = 0.025 pCi/g;
Subscenarios 3 & 4 = 1 pCi/g
10,000
100
0.15
0.916/Uniform(0.413, 0.916)
0
See Chapter3.
About 2 acres
(EPA, 1988b)
Square root of area
Default plowing depth
To get an infiltration rate ranging
from 0.03 m/yr to 0.22 m/yr
No irrigation on the landfill area
Cover
Thickness (m)
Bulk density (g/cm3)
Total porosity
Soil credibility factor
Volumetric water content
0.5
1.52
0.427
0.3
0.427
Standard thickness for clay layer
HELP model default (Schroeder
et al, 1994)
Default value of
RESRAD-Offsite, results in
erosion rate of 0.001 m/yr.
Set to the total porosity value to
obtain the desired infiltration rate.
Contaminated Zone
Thickness (m)
Total porosity
Dry bulk density (g/cm3)
2
0.671 for MSW landfill and 0.427
for surface impoundment
1.18 for MSW landfill and 1.52
for surface impoundment
Total 20,000 m3 of sludge or
waste
From Table 3.3 for MSW landfill,
for surface impoundment, the
value corresponds to that of
sewage sludge.
The average value of the range as
specified in Table 3.3 is 1.18.
Final, February 2005
4-15
ISCORS Technical Report 2004-03
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Table 4.4b Landfill Neighbor Scenario Parameter and
Distributions—Post-Monitoring Period (continued)
Parameter
Field capacity
Hydraulic conductivity (m/yr)
Value / Distribution
0.292 for MSW landfill and 0.2
for surface impoundment
3 15 for MSW landfill;
9.974/{Bounded LogNormal (2.3,
2.11, 0.004, 9250)} for surface
impoundment
Comments
From Table 3.3 for MSW landfill,
0.2 is the RESRAD default value.
From Table 3.2 for MSW landfill,
soil value for surface
impoundment
Unsaturate d zone 1 (liner)
Thickness (m)
Hydraulic conductivity (cm/s)
Total Porosity
Air Transport Parameters
Ingrowth factor for Rn -222
progeny
c/Q, all
Groundwater Transport
Parameters
Distance from down-gradient
edge of contamination to well in
the direction parallel to aquifer
flow (m)
Distance from down-gradient
edge of contamination to surface
water body in the direction
parallel to aquifer flow (m)
External Radiation Shape and
Area Factor
0.5
0.03 / {Uniform(0.03,0.22)}
0.427
0.265
see Table 3.4
150
150
Standard thickness for clay layer
Same as the infiltration rate
HELP model default (Schroeder
et al, 1994)
Adjusted CAP88PC value for a
wind speed of 4.24 m/s at 150 m
Collocate the well with the
receptor.
Collocate the surface water body
with the receptor
Off-site
Scale (m)
Receptor location X (m)
Receptor location Y (m)
600
506
300
Circular landfill, 56m radius,
receptor is 150m from its edge.
ISCORS Technical Report 2004-03
4-16
Final, February 2005
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4.5 INCINERATOR NEIGHBOR SCENARIO
The Incinerator Neighbor scenario models the potential for exposure of a member of the public
residing near a typical sewage sludge incineration facility. The incinerator burns de-watered
sludge, and the resulting exhaust gas is released from the top of a stack as a plume, some of
which settles onto the Neighbor's property. The exposed individuals reside on a small, farm
located at the point of maximum average annual air radionuclide concentration of the plume at
ground level. The farm already existed when the incinerator facility was constructed, so
exposure begins immediately after the POTW begins burning sludge. The incinerator will
operate at nearly 100% capacity for 50 years, after which it is shut down and decommissioned.
Since the residual ash from the process has no impact on the critical population group, it is not
considered here. Table 4.5a summarizes the applicable pathways. Residual exposure and dose
from plant operations are modeled out to 1,000 years.
The Incinerator Neighbor receives doses from external exposure, inhalation, and ingestion.
External exposure occurs from submersion in the plume, and from radiation emitted by nuclides
that have been deposited on the ground. Inhalation of activity in the plume also leads to dose.
Ingestion exposure comes from drinking contaminated water, eating plant foods raised by the
Incinerator Neighbor that have activity either on their surface or taken up through the roots, or
by eating meat or drinking milk from livestock that have ingested contaminated feed or water.
The parameters used in RESRAD-OFFSITE for this scenario are identical to those defined in the
Nearby Town Resident scenario, with the exception of some those listed in Table 4.5b.
Final, February 2005 4-17 ISCORS Technical Report 2004-03
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Table 4.5a Incinerator Neighbor Pathways
Exposure
Pathway
External
radiation
Inhalation
Ingestion of
water
Ingestion of
plants
Ingestion of
meat / milk
Ingestion offish
Ingestion of soil
Environmental Pathway
Direct exposure
Plume inhalation
Indoor radon
Outdoor radon
Groundwater
Surface water
Irrigation water
Dust deposition
Root uptake
Livestock water
Livestock soil
Irrigation water
Fodder Dust deposition
Root uptake
Surface Water
Surface soil
Pathway
Included?
Yes
Yes
No
Yes
No
No
No
Yes
Yes
No
Yes
No
Yes
Yes
No
Yes
Comments
Plume submersion and
groundshine
Exposed individual placed in
the sector with highest
concentration
In plume, and emanating from
deposited radionuclides
Surface deposition of
transported nuclides
Deposition of transported
effluent
ISCORS Technical Report 2004-03
4-18
Final, February 2005
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Table 4.5b Incinerator Neighbor Scenario Parameters and Distributions
Parameter
Value / Distributions
Comments
Dispersion Calculation in CAP88-PC
Lid Height (m)
Stack Height (m)
Stack Diameter (m)
Stack Exit Velocity (m/sec)
1,000
13
1
1
From Easterly (Ohio) incinerator;
typical of older incinerators with stack
height less than the 65 ft. 'good
engineering practice' height from the
Part 503 rule risk assessment
Easterly incinerator
Easterly incinerator
Appendix A baseline values and distributions, except ...
Radiation Dose Calculation in RESRAD-Offsite
Annual release rate of
radionuclide from the incinerator
(pCi/yr)
Sediment delivery ratio
c/Q, all
Fraction of water from surface
body
Household purposes
- Beef cattle
- Dairy cows
- Irrigation for fruit, grain,
non-leafy vegetable field
- Irrigation for leafy vegetable
field
- Irrigation for livestock
pasture and silage field
- Irrigation for livestock grain
field
For each radionuclide
of concern
0
see Table 3.6
0
0
0
0
0
0
0
No primary soil contamination source,
therefore, no contaminant delivery to
surface water
Household water and irrigation water
are not contaminated because there is
no primary soil contamination source.
Final, February 2005
4-19
ISCORS Technical Report 2004-03
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Table 4.5b Incinerator Neighbor Scenario Parameters and Distributions
(continued)
Parameter
Value / Distributions
Comments
Fraction of water from well
Household water and irrigation water are
not contaminated because there is no
primary soil contamination source.
Distance from down gradient edge
of contamination to
- Well in the direction parallel
to aquifer flow (m)
- Surface water body in the
direction parallel to aquifer
flow (m)
0
0
The value does not affect the dose results
However, to reduce the calculation time,
a value of 0 was specified.
Distance from center of
contamination to well in the
direction perpendicular to aquifer
flow (m)
The value does not affect the dose results
However, to reduce the calculation time,
a value of 0 was specified.
Fraction of time spent off-site,
within the range of radiation
emanating from primary
contamination
- Indoors
- Outdoors
0
0
No primary contamination source
4.6 SLUDGE APPLICATION WORKER SCENARIO
A sludge application worker engaged in the agricultural application of sludge to fields typically
drives or works on a truck, tractor, or other vehicle that dispenses liquid, de-watered, or dried
sludge at a fairly constant rate. Radiation exposures from the application of sludge would be
primarily by way of external exposure and dust inhalation. External exposure is calculated both
for the sludge being applied at the time as well as sludge applied from previous applications
(5 years, 20 years, 50 years, and 100 years). Because individuals working with sewage sludge
are known to practice reasonable hygiene, inadvertent hand-to-mouth transfer or other ingestion
of sludge is not considered here. Table 4.6a summarizes the exposure pathways considered. The
driver is assumed to be situated above the ground on the truck, which provides some shielding.
De-watered sludge cake, which is applied as a fertilizer or soil amendment, is typically
10 percent to 20 percent solids, so there is little dust loading (Metro 2000). Sludge may also be
applied in liquid or semi-liquid form, where dust generation would be even less. If the sludge is
heat dried or mixed with other materials and composted, however, the resulting moisture content
can be low. Since differences in the inhalation of dust is the dominant issue here, the scenario
will consider the limiting case of the application of dry sludge to be more conservative.
Table 4.6b presents the non-baseline parameter values.
ISCORS Technical Report 2004-03
4-20
Final, February 2005
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Table 4.6a Agricultural Application Worker Pathways
Exposure
Pathway
External radiation
Inhalation
Ingestion of water
Ingestion of plants
Ingestion of
meat / milk
Ingestion offish
Ingestion of soil
Environmental Pathway
Direct exposure
Resuspended dust
Indoor radon
Outdoor radon
Groundwater
Surface water
Irrigation water
Dust deposition
Root uptake
Livestock water
Livestock soil
Irrigation water
Fodder Dust deposition
Root uptake
Surface Water
Surface soil
Pathway
Included?
Yes
Yes
No
Yes
No
No
No
No
No
No
No
No
No
No
No
No
Comments
Assume industrial hygiene
practices
Final, February 2005
4-21
ISCORS Technical Report 2004-03
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Table 4.6b Agricultural Application Worker Scenario Parameters and
Distributions
Subscenario
1
(Uncertainty)
Parameter
Years of application
Times for
Calculation (yr)
Cover (shielding)
thickness (m)
Cover (shielding)
density
Cover (shielding)
erosion
Receptor distance
from the ground, m
Inhalation rate
(m3/yr)
Mass loading for
inhalation (g/m3)
Exposure Duration
(y)
Indoor time fraction
Outdoor time
fraction
Value / Distribution
Appendix A baseline
values, distribution
lyr
1
0.003
7.87
0
1
14,600, Triangular
(4750, 7300, 28900)
3xlO~4,
Uniform (lx 10 ~4,
5xlO~4)
1
0
0.23
Comments
Worker is only present
during the application of
sludge
Based on observed sludge
application equipment
density of steel
No erosion of the shielding
Inhalation rate distribution
for adult male for typical
outdoor activity levels from
NRC (2000b) (NUREG/CR-
6697).
Values are for average
conditions outdoor during
gardening from NRC
(1992b) (NUREG/CR-5512,
Volume 1)
Worker is only present
during the application of
sludge
Worker is engaged in
application of sludge at the
field
Based on the assumption that
the application worker
spends 8 h/d for 250 d/yr in
the field.
ISCORS Technical Report 2004-03
4-22
Final, February 2005
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Table 4.6b Agricultural Application Worker Scenario Parameters and
Distributions (continued)
Subscenario
2-6
(Deterministic)
All
2
O
4
5
6
Parameter
Log / linear spacing
Number of graphic
points
Years of application
Years of application
Years of application
Years of application
Years of application
Value / Distribution
Appendix A baseline
and Subscenario 1
values, except...
Linear
1024
1
5
20
50
100
Comments
Not applicable
To obtain annual dose results
for each year
To obtain the largest number
of annual doses in a single
run
NA
NA
NA
NA
NA
4.7 PUBLICLY OWNED TREATMENT WORKS WORKER SCENARIO
The purpose of this scenario is to consider potential radiation exposures of POTW workers. As
should be apparent from the above, the operation of any one POTW involves a range of tasks,
in addition to which there is a high degree of variability among POTWs in sludge handling
processes. Our scenarios cannot encompass the entire scale of potential exposure situations, but
it appears that there are three tasks that are representative and/or involve relatively high
exposures to the sludge. These are (a) sludge sampling and sample transport to the lab for
analysis, (b) sludge processing, and (c) biosolids loading. For all three of these tasks, exposures
are due primarily to direct gamma exposure and radon (if radon precursors are present). For the
third sub-scenario, inhalation is considered a possible exposure pathway as well. Because the
biological hazard of the sludge is high, workers generally practice good industrial hygiene, so
that inadvertent sludge ingestion, in particular, is omitted from the analysis.
4.7.1 SLUDGE SAMPLING
Once the raw sludge is separated from the treated wastewater effluent, it is sampled periodically.
Samples may also be taken from digesters, dewatering devices, mixers, storage tanks, trucks, and
from other processes that are used to treat, condition or transport the sludge. If automated
equipment for this sampling process is not employed, then once a shift or so, an operator must
manually collect sludge samples (typically about 1 liter) for analysis. The solids content is about
3 to 6 percent at this point. The worker carries the sample to the analytical laboratory, and may
Final, February 2005
4-23
ISCORS Technical Report 2004-03
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personally test it for percent total solids and volatile organics. The total duration of the
procedure is about 5 minutes, during all of which time the operator is in close contact with
sludge. Table 4.7a indicates the pathways that are active and included..
During the sampling process, a worker could be exposed to external radiation. Owing to the
considerable biological hazard of the material, however, workers generally practice a high
degree of industrial hygiene during this operation, and it appears that other potential exposure
pathways will not be significant on a routine basis. (If an accident such as the splashing of waste
onto an operator occurs, of course, inhalation, dermal, and other exposure pathways may be of
importance. But such accident conditions are rare, and they are not considered further in this
report.) It is assumed that a 1-liter sample containing 5% by volume solids is a point source held
for 5 minutes at waist level and at a distance of 0.5 m. The activity in the sample was derived in
Chapter 3. Self-shielding by the sample container and water are neglected.
Exposures calculated from this scenario are expected to be somewhat conservative, since the
actual sampling procedure includes some time during which the sample is being centrifuged and
otherwise manipulated, so that additional shielding and distance apply. Preliminary
investigation revealed that the scenario leads to small doses, so probabilistic analyses have not
been performed.
The parameters used with RESRAD-BUILD are presented in Table 4.7b. The doses calculated
are for one working shift.
4.7.2 SLUDGE PROCESSING WITHIN PUBLICLY OWNED
TREATMENT WORKS
This sub-scenario considers a situation in which an operator's workspace is located adjacent to a
conveyer belt transporting sludge cake, Table 4.7a. The cake is typically about 20% solids, so
the air dust loading around the conveyer is assumed to be very low, but there is a potential of
receiving a dose from external exposure.
The relevant parameters appear in Table 4.7b. The conveyer is represented by a line source (see
Chapter 3 for additional source details). The operator is located 3 m from the belt, which would
be a minimum distance for significant amounts of time near a mechanical operation with no
noise abatement.
Dose per hour adjacent to the conveyer belt is computed. The scenario is conservative but,
again, because of the low exposures, no probabilistic analysis is needed.
4.7.3 BIOSOLIDS LOADING/STORAGE
This sub-scenario is more likely to lead to both external and inhalation exposures. The worker
spends his time next to a pile of dewatered sludge (roughly 100 square meters in area). The
operations involve loading sludge at a POTW for transport offsite (into bags, trucks, or other).
The worker may be in an area of some dust loading, but it is controlled (e.g., through wetting
down or use of respirator) so as to not violate OSHA regulations. Exposures in this situation will
ISCORS Technical Report 2004-03 4-24 Final, February 2005
-------
be from (1) external exposure from the sludge pile, (2) external exposure from immersion in a
cloud of airborne dust or vapors, and (3) inhalation of contaminated dust.
RESRAD-BUILD is used to model the exposures for this scenario. Table 4.7b lists those
parameters that differ from the baseline values. See Chapter 3 for source details.
It is conservatively assumed that during work in the area of the sludge pile, the worker stands at
the edge of the slab source. Based on comments received on the draft report (see Appendix F),
the previously used value of 2000-hours of exposure time per year appears unrealistically high.
For the present report, a value of 1000-hours of exposure time per year has been used. This
value of exposure time is known to be plausible at some POTWs, but it is more likely to be
lower at most POTWs. Reductions (or increases) in exposure times at individual POTWs (all
other conditions being equal) would result in proportionally lower (or higher) doses. DSRs, and
thus doses, for all radionuclides have been recalculated accordingly. No shielding is included in
the calculation.
The computed DSRs for radium-226 and Th-228 for the POTW loading worker, which are
dominated by radon contributions, depend strongly on the room air exchange rate and the height
of the room. Based on comments received on the draft report (see Appendix F), it appears that
the values previously used for the building height and air exchange rate were unrealistically low.
However, only limited data on these parameters specific to POTW facilities were available.
Thus, for this present report, nine combinations of building height and air exchange rate have
been used, with building heights of 2 m, 4 m, and 6 m, and air exchange rates of 1.5, 3, and 5 per
hour. These parameters primarily affect the doses from inhalation of radon progeny, so
recalculations of DSRs and doses have been performed only for Ra-226 and Th-228.
It is difficult to assess the range of working conditions and practices for this scenario. The
conditions have been chosen to represent a situation as observed at one real POTW, but those at
other POTWs are likely to differ significantly from these, owing to the various possible uses for
the sludge and the varied methods for processing it.
Final, February 2005 4-25 ISCORS Technical Report 2004-03
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Table 4.7a All POTW Worker Pathways
Exposure
Pathway
External radiation
Inhalation
Ingestion of
water
Ingestion of
plants
Ingestion of
meat / milk
Ingestion offish
Ingestion of soil
Environmental Pathway
Direct exposure
Submersion
Resuspended dust
Indoor radon
Outdoor radon
Groundwater
Surface water (runoff)
Irrigation water
Dust deposition
Root uptake
Livestock water
Livestock soil
Irrigation water
Fodder Dust deposition
Root uptake
Surface Water
Surface soil
Pathway
Included?
Yes
Yes
Yes
Yes
No
No
No
No
No
No
No
No
No
No
No
No
No
Comments
All cases
Immersion in cloud of dust,
only for biosolids loading
Only for biosolids loading
Only for transport and
biosolids loading
Assumes industrial hygiene
practices eliminate ingestion
ISCORS Technical Report 2004-03
4-26
Final, February 2005
-------
Table 4.7b General POTW Worker Sub-Scenario Parameters and Distributions
Subscenario
1 - Sludge
sampling
(Deterministic)
2 - Processing
(Deterministic)
Parameter
Exposure Duration
(d)
Indoor Fraction
Max. No. of Points
for Time Integration
Source Type
Activity
Concentration, pCi
Air Release Fraction
Receptor Location
Exposure Duration
(d)
Indoor Fraction
Max. No. of Points
for Time Integration
Source Type
Source Direction
Source Length (m)
Activity
Concentration, pCi/m
Value / Distribution
Appendix A baseline
values, except...
1
3.47xl(T3
1
Point
75
0
(0, 0, 0.5)
Appendix A baseline
values, except...
1
4.17xl(T2
1
Line
X
50
3,000
Comments
To get a total exposure
time of 5 minutes
Instantaneous dose is
calculated
To suppress all air
dependent pathways
Receptor at a distance of
0.5 m from the source
Scenario definition
To get a total exposure
time of 1 hour
Instantaneous dose is
calculated
Scenario definition
Final, February 2005
4-27
ISCORS Technical Report 2004-03
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Table 4.7b General POTW Worker Sub-Scenario Parameters and Distributions
(continued)
Subscenario
2 - Processing
(Deterministic)
3 - Biosolids
loading
(Probabilistic)
4 - Biosolids
loading
(Deterministic)
Parameter
Air Release Fraction
Removable Fraction
Radon Release
Fraction
Source Lifetime, d
Receptor Location
Indoor Fraction
Indoor Fraction
Value / Distribution
0 or 0.357
0.1
0.1
10,000
(0,0,3)
Appendix A baseline
distributions, values,
except...
0.114
Appendix A baseline
values, except...
0.114
Comments
Zero, to suppress all air
dependent pathways for
all radionuclides except
for radon precursors,
where air release fraction
of 0.357 is used
Receptor at a distance of
3 m from the source
To get a total exposure
time of 1,000 hours in one
year
To get a total exposure
time of 1,000 hours in one
year
ISCORS Technical Report 2004-03
4-28
Final, February 2005
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5 SENSITIVITY, AND UNCERTAINTY AND VARIABILITY
5.1 SENSITIVITY
A number of sensitivity analyses were performed to ensure that the source analysis methods in
this study are robust. These rely on previous sensitivity analyses carried out on the RESRAD
family of codes. In particular, the recent NRC documents NUREG/CR-6676 and
NUREG/CR-6697 list and categorize the various parameters used in RESRAD and
RESRAD-BUILD, and rank the degree of influence of each on calculation results
(NRC 2000a,b). These documents also developed distributions for high ranking parameters, and
these were used in the present analysis.
Of particular interest are the assumptions employed in implementing the multiple-years of
application source term. Sensitivity analyses on these assumptions (e.g., parameters such as
erosion rate and water table drop rate set to zero) indicated that the results are not significantly
affected.
5.2 SCENARIO UNCERTAINTY AND VARIABILITY
5.2.1 EXPOSURE ENVIRONMENT
The range of exposure groups and situations developed for this analysis was felt, by the
Subcommittee, to be typical and 'reasonable.' There may exist, however, certain combinations
of parameters that lead to radiation exposures that are greater or less than those calculated here.
In exploring this variability, the Subcommittee noted, in particular, that the POTW worker
scenarios display a broad array of site configurations and operations across the country. Thus, to
partially address this variability, for the POTW worker loading scenario, calculations were
performed for a number of different combinations of facility characteristics; this may provide a
closer match to actual facilities.
5.2.2 EXPOSED POPULATIONS: CHILDREN/INFANTS
The effect of variability in the age of the exposed populations is not fully addressed in this
analysis. This is partially due to the choice (described in Chapter 1) to use dose coefficients
based on the methods of ICRP 26 and ICRP 30, as contained in Federal Guidance Reports 11
and 12 (EPA 1988a, 1993a). A qualitative understanding of the relative impacts on infants and
children can be derived from Report No. 129 of the National Council on Radiation Protection
and Measurements (NCRP 1999), however, which derives ratios for the dose coefficients as well
as intake factors for children (10 yr old) versus adults, and for infants versus adults. For the
radionuclides and dominant pathways of interest, the ratios are in almost all cases less than a
factor of 2. This is small compared to the parameter uncertainty/variability calculated using
Monte Carlo methods (see below) as well as compared to the source variability seen in the
NRC/EPA national survey of radioactivity in sewage sludge and ash.
Final, February 2005 5-1 ISCORS Technical Report 2004-03
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5.3 PARAMETER UNCERTAINTY AND VARIABILITY
The main means of incorporating uncertainty and variability into the computations was through
the use of distributions for certain input parameters. Table 5.1 summarizes uncertainties and/or
variability characterized by distributions for selected parameters. Additional detail is contained
in NRC (2000b). In many cases, the use of a distribution reflects both uncertainty and
variability.
The results of the parameter uncertainty/variability analysis using the probabilistic RESRAD
codes are summarized in Table 5.2. The tabulated values of the ratio of the 95% to the 5% DSR,
in particular, characterize the range of uncertainty and variability in the DSRs, and reflect the
choice of parameter distributions chosen.
Another sources of parameter uncertainty and variability is that the inhalation dose coefficients
from FGR 11 (EPA 1988a) have different values for different clearance rates (typically days,
weeks, or years). Because of the generic nature of this assessment, no assumptions were made
about the distributions of sizes and clearance rates of suspended particles from sewage sludge,
but rather the largest inhalation dose coefficient was chosen.
Many parameters in this assessment may be correlated, and the analysis includes correlation
coefficients that can be well characterized and justified for a generic site10. For instance, the
partition coefficients of U-234, U-235, and U-238 are set to be correlated because the transport
characteristics are isotope-independent. Some correlations, such as that between the total and
the effective porosities, are discussed in NRC (2000a).
Table 5.1 Parameters and their Uncertainties and Variability
Parameter
Uncertainty Characterized by
Distribution
Variability Characterized by
Distribution
Hydrogeological parameters
Distribution Coefficients
Total and Effective Porosities
Hydraulic Conductivities
Soil b parameter
The possibility of rapid transport
due to fracture flow and/or
colloidal transport.
—
The possibility of rapid transport
due to fracture flow and/or
colloidal transport.
—
Variability of published measured
or estimated values.
Variability of published measured
or estimated values based on
national databases.
Variability of published measured
or estimated values based on
national databases.
Variability of published measured
or estimated values.
10 Additional correlations may need to be considered for specific sites.
ISCORS Technical Report 2004-03 5-2
Final, February 2005
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Table 5.1 Parameters and their Uncertainties and Variability (continued)
Parameter
Hydraulic Gradient
Unsaturated Zone Thickness
Well pump intake depth
Depth of Soil Mixing Layer
Uncertainty Characterized by
Distribution
—
—
Uncertainty in actual intake depths
—
Variability Characterized by
Distribution
Variability of published measured
or estimated values.
Variability across continental U.S.
Variability in aquifer thicknesses.
Variability in natural (wind,
precipitation) and man-made
processes (tillage).
Human Intake Parameters
Inhalation Rate
Soil Ingestion Rate
Drinking Water Ingestion Rate
Milk Consumption Rate
—
Uncertainty in adults due to limited
data.
—
Uncertainty due to limited data and
changes over time.
Variability in adults due to
differences in long-term patterns of
time and activity.
Variability in adults. Distribution
includes mean rate for children.
Variability in adults.
Variability across adults and
children.
Crops and Livestock Parameters
Plant, Meat, Milk, and Fish
Transfer factors
Depth of roots
Uncertainty in the transfer factor
method.
—
Variability among different sites
and foodstuffs.
Variability amongst different plant
types and growing conditions
Building Characteristics parameters
Indoor dust filtration factor
External Gamma Shielding
Factor
—
—
Variability amongst different
buildings, climates, and seasons.
Variability amongst different home
constructions
Other parameters
Resuspension Rate
Shielding Density
Uncertainty due to limited data.
—
Variability amongst different sites.
Variability amongst different
substances.
Note:
Additional detail on these parameters and others can be found in Yu et al. 2000.
Final, February 2005
5-3
ISCORS Technical Report 2004-03
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Table 5.2 Parameter Uncertainty/Variability Results
Ratio of 95% DSR to 5% DSR
Radio-
nuclide
Ac-227
Am-241
Be-7
C-14
Ce-141
Co-57
Co-60
Cr-51
Cs-134
Cs-137
Eu-154
Fe-59
H-3
1-125
1-131
In-Ill
K-40
La-138
Np-237
Pa-231
Pb-210
Po-210
Pu-238
Pu-239
Ra-226
Ra-228
Sm-153
Sr-89
Sr-90
Th-228
Th-229
Th-230
Th-232
Tl-201
Tl-202
U-233
U-234
U-235
U-238
Xe-131m
Zn-65
Onsite
Resident
2.9
5.6
2.2
76.1
2.2
2.3
2.3
2.2
2.3
2.7
2.2
2.2
8.9
12.8
2.5
2.2
2.2
8.0
74.9
22.1
9.9
20.2
7.0
6.8
1.2
2.4
2.1
28.2
35.9
2.0
2.2
62.6
3.9
2.2
2.2
18.9
19.2
2.9
4.7
2.3
6.2
Recrea-
tional
User
1.2
1.2
1.0
557.7
1.0
1.
1.
1.
1.
1.
1.
1.
11.8
5.3
1.1
1.0
1.2
4.1
744.8
22.9
3.0
7.8
1.2
1.2
1.1
1.1
1.0
8.2
25.8
1.1
1.1
46.7
2.1
1.0
1.1
150.8
112.6
4.9
14.5
1.3
1.8
Nearby
Town
6.2
6.4
7.3
2.0
4.2
12.7
9.6
9.0
18.7
14.9
8.2
9.0
3.9
8.6
8.6
7.7
8.55
14.7
6.8
17.7
6.1
4.8
6.1
5.8
1.0
1.1
6.4
5.0
15.3
1.0
6.0
29.5
3.0
16.2
16.6
7.7
6.2
6.8
6.2
1.0
12.0
Landfill
(MSW)
Neighbor
114.7
185.1
1.0
1.0
1.0
1.0
1.1E+03
1.0
1.0
110.4
412.2
1.0
1.0
1.0
1.0
1.0
1.2E+08
4.1E+32
4.8E+08
3.3E+04
81.4
1.0
11.9
11.6
1.5
11.1
1.0
1.0
1.2E+07
1.0
35.7
4.2
5.2
1.0
1.0
114.4
28.7
84.8
8.8E+03
1.0
1.0
Landfill
(Surface
Impound-
ment)
Neighbor
53.6
90.9
1.0
4.2E+12
1.0
1.0
404.8
1.0
1.0
63.2
95.9
1.0
8.2E+29
1.0
1.0
1.0
2.1E+07
6.1E+33
2.8E+08
5.0E+03
77.2
1.0
1.1
12.5
1.3
12.1
1.0
1.0
5.8E+06
1.0
25.3
3.5
3.1
1.0
1.0
104.9
23.8
224.0
3.7E+04
1.0
1.0
Incinerator
Neighbor
2.0
2.0
3.0
2.1
1.7
5.4
3.8
4.4
4.6
5.2
2.6
4.3
2.1
6.0
6.0
5.1
4.7
5.4
2.0
2.0
1.9
2.5
2.0
2.0
3.0
2.1
3.8
2.7
9.0
2.0
2.0
2.1
2.0
11.6
9.3
2.0
2.0
2.0
2.0
1.0
7.5
Sludge
Application
Worker
4.5
8.7
1.1
4.7
.0
.1
.2
.1
.1
.1
.1
.1
5.2
.8
.1
.0
.2
5.7
3.0
19.6
5.2
12.2
12.6
12.7
.0
.1
.0
.2
.6
.1
2.6
26.3
2.6
1.0
1.1
18.6
13.2
2.1
2.7
1.3
1.6
POTW
Worker
(loading)
4.8
14.8
.0
.3
.0
.0
.0
.0
.0
.0
.0
.0
18.8
.0
.0
.0
.0
.0
213.3
9.6
6.4
99.1
187.5
251.9
1.0-1.8*
1.0
1.0
1.0
1.1
1.2-2.9*
2.6
142.6
219.4
1.0
1.0
88.3
131.0
1.2
2.0
1.0
1.0
* Range represents results from the nine combinations of air exchange rate and room height (see Section 4.7.3).
ISCORS Technical Report 2004-03
5-4
Final, February 2005
-------
5.4 MODEL UNCERTAINTY
Chapters 1 and 2 included discussion of the limitations of the generic modeling performed here.
This section describes uncertainties from the use of the RESRAD computer codes.
5.4.1 TREATMENT OF SURFACE WATER
Surface waters range from ponds maintained by groundwater and local runoff to long, rapidly
flowing rivers fed by vast watersheds. RESRAD and RESRAD-OFFSITE do not make that
distinction, but rather focus on the amount of dilution of the contaminated water and sediment
that reach the surface water. RESRAD uses only the watershed area in calculating a dilution
factor relative to the aquifer. RESRAD-OFFSITE also considers runoff, and requires other
variables, such as the residence time, the water body volume, the distance from the river to the
contaminated zone, the sediment delivery ratio, and depth relative to the ground water table.
The methodology developed to address multiple years of application requires that surface water
be contaminated only by means of ground water, i.e., not by runoff from a field upon which
sludge has been applied (this is to ensure mass balance over multiple applications). Also, the
rate of erosion of surface soil is set to zero in the calculation of leaching of radionuclides
downward from the source level, and the depth of the water table is held fixed over time. The
relatively conservative RESRAD default watershed area was used adopted to compensate
somewhat for the uncertainties introduced by these assumptions,
5.4.2 OFFSITE EXPOSURES
A basic assumption of the offsite analyses is that contaminated dust is blown from the source to
the receptor and other neighboring fields, but that further transport is governed by local
conditions. In reality, transport is determined largely by the details of the balance between the
amount of wind-blown dust settling and staying on a town or neighboring fields, on the one
hand, and the amount that is blown or washed away. In other words, is the amount of
contaminated dust that is blown into the town equal to or less than that which is blown away, or
is there a residual that remains in the town and could be a source of exposure?
Even a relatively simple calculation of this balance requires detailed knowledge of the joint
frequency-of-occurrence spectrum of the puffs of wind of various magnitudes that sweep over
the source site and then over the receptor, the size distribution of dust particles both places,
temporal patterns of precipitation, and numerous other factors for which it would be difficult to
make defensible modeling assumptions and approximations. In view of the great uncertainty and
variability in these factors, this analysis assumes (as does most other air transport and dose
modeling) that little activity is removed from the contaminated top layer of soil by erosion,
weathering, or leaching. Deposited material acts, rather, like a new, thin-layer addition to the
contaminated zone source available for leaching, and for uptake via the pathway models for
ingestion, inhalation, external, etc.
Final, February 2005 5-5 ISCORS Technical Report 2004-03
-------
5.4.3 INFILTRATION RATE FOR LANDFILLS/SURFACE
IMPOUNDMENTS
It is assumed that after the 30-year monitoring period, infiltration through a landfill or surface
impoundment can be handled with a simple soil model. In particular, the default infiltration rate
assumed in RESRAD is about 50 cm/yr. Since it is not obvious that this provides an adequate
representation of landfill performance, the Hydrologic Evaluation of Landfill Performance
(HELP) code was also applied to the scenario. The HELP model performs a detailed water
balance calculation accounting for many more processes than the RESRAD code
(Schroeder et al., 1994).
The HELP model found that for a typical municipal solid waste landfill, the leakage rates
(infiltration through the bottom layer) is negligible (much less than 1 cm/yr). For a "worst case"
scenario under modern-day practices, the HELP model calculated an infiltration rate of 3.3 cm/yr
out of 107 cm/yr of precipitation, with leachate at about 46 cm/year. For a "worst case" scenario
that assumes a high rate of liner defects in the range of those found at very old facilities, the
HELP model calculated an infiltration rate of 22 cm/yr (again out of 107 cm/yr of precipitation),
with leachate at about 25 cm/yr. Unfortunately, there is very little data on the long-term
performance of cover/liner systems.
Based on these calculations, the probabilistic calculations in this assessment assume an
infiltration rate that is distributed between 0.03 m/yr and 0.22 m/yr. This is considered
reasonably conservative, especially given the 1,000-year modeling framework, but not extreme
in light of the uncertainties. However, the uncertainty in the value remains significant, and may
exceed the range used in the calculation.
ISCORS Technical Report 2004-03 5-6 Final, February 2005
-------
6 SUMMARY OF DOSE-TO-SOURCE RATIOS
6.1 INTRODUCTION
This chapter presents an overview of the results of the probabilistic DSR calculations. The
detailed results are tabulated in Appendix E.
As discussed in Section 2.4.4, the probabilistic version of RESRAD runs J realizations, and
generates J curves of dose as a function time, dsi}(Y),y= 1 ... J, for every scenario and for
every radionuclide (set at unit specific activity in dry sludge). As shown in Equation 6.1, each
dsi}(X) has a maximum value, called DSR,,
DSR, = Max[dsr/0] , (6.1)
and the set of these maximum values, (DSRy}, itself comprises a distribution. It is the
95-percentile values from this distribution that populate the DSR tables below; other percentile
values are contained in Appendix E. It is a standard practice to consider a relatively
conservative percentile value when an assessment is generic and not site-specific (in a
site-specific assessment, it may be appropriate to use a measure of central tendency). The major
pathway(s) is(are) also reported.
In addition, if a radionuclide has more than 10% of its dose through the indoor radon pathway,
then an "*" is marked in the "Critical Pathway(s)" column. The indoor radon pathway breakouts
with radon and non-radon components are listed in separate tables. These tables present the non-
radon DSR in mrem/year per pCi/g, and the indoor radon DSRs in three different units:
mrem/year per pCi/g, Working Levels per pCi/g, and pCi/liter of the appropriate radon daughter
per pCi/g. The latter two are actually "concentration to source ratios," since Working Levels and
pCi/liter are both concentration units.
6.2 LAND APPLICATION SCENARIOS
The following Tables give the 95% DSRs for the land application scenarios, as well as the
multiple year scaling factors (as discussed in Section 3.2.2), where appropriate. Table 6.1
presents the total DSRs, which include doses due to radon and other, non-radon exposure
pathways, while Table 6.2 presents the DSRs for the radon pathway only. Several general
characteristics are of note. The Onsite Resident calculations had the highest DSRs for most of
the radionuclides, in particular when multiple years of application were considered. The
radionuclides with the highest calculated DSRs are Np-237 and Ra-226.
In a few cases (C-14, Np-237, U-233, U-234, and U-238), the Recreational User scenario had
larger DSRs than the other land application scenarios under the assumption of a single
application. This is largely due to the ten times larger source term in the Recreational scenario.
In no cases were the Recreational User DSRs the largest when multiple years of application were
considered in the other scenarios. In the case of certain radionuclides with very short half-lives
(1-131, In-Ill, Sm-153, Tl-201, and Tl-202), the Nearby Town scenario gave the highest DSRs
Final, February 2005 6-1 ISCORS Technical Report 2004-03
-------
because of the rapid exposure through the air transport pathway. However, these DSRs were all
very small (less than 0.001 mrem/yr per pCi/g). Indoor radon was only a significant component
of the dose for the Onsite Resident with Ra-226 and Th-228. In the case of Ra-226, radon was
the dominant pathway.
Table 6.1 Onsite Resident Scenario Total DSR Results (mrem/yr per pCi/g)
Radio-
nuclide
Ac-227
Am-241
Be-7
C-14
Ce-141
Co-57
Co-60
Cr-51
Cs-134
Cs-137
Eu-154
Fe-59
H-3
1-125
1-131
In-111
K-40
La-138
Np-237
95% Peak
Total DSR
1.06e-02
1.43e-03
1.63e-04
2.42e-02
1.19e-04
1.03e-03
4.06e-02
5.26e-05
2.63e-02
1.35e-02
1.88e-02
3.43e-03
1.20e-05
6.09e-04
2.79e-04
1.18e-04
2.34e-03
1.78e-02
2.42e-01
Critical
Pathway(s)
External
Plant and Soil
Ingestion
External
Meat and
Plant
Ingestion
External
External
External
External
External
External
External
External
Water
Meat
External
External
External
External
Fish
Scaling Factors
1
9.67e-01
9.98e-01
8.61e-03
l.OOe+00
4.13e-04
3.91e-01
8.72e-01
1.06e-04
7.13e-01
9.74e-01
9.23e-01
3.38e-03
l.OOe+00
1.16e-02
1.73e-14
O.OOe+00
8.05e-01
7.91e-01
l.OOe+00
5
4.53e+00
4.96e+00
8.68e-03
5.00e+00
4.13e-04
6.35e-01
3.38e+00
1.06e-04
2.02e+00
4.63e+00
3.96e+00
3.39e-03
4.51e+00
1.17e-02
1.73e-14
O.OOe+00
2.73e+00
2.59e+00
5.00e+00
20
1.44e+01
1.95e+01
8.68e-03
2.00e+01
4.13e-04
6.41e-01
6.38e+00
1.06e-04
2.48e+00
1.54e+01
9.56e+00
3.39e-03
1.29e+01
1.17e-02
1.73e-14
O.OOe+00
4.07e+00
3.69e+00
2.00e+01
50
2.39e+01
4.70e+01
8.68e-03
4.99e+01
4.13e-04
6.41e-01
6.82e+00
1.06e-04
2.48e+00
2.77e+01
1.17e+01
3.39e-03
1.41e+01
1.17e-02
1.73e-14
O.OOe+00
4.13e+00
3.73e+00
5.00e+01
100
2.85e+01
8.86e+01
8.68e-03
9.95e+01
4.13e-04
6.41e-01
6.82e+00
1.06e-04
2.48e+00
3.53e+01
1.20e+01
3.39e-03
1.41e+01
1.17e-02
1.73e-14
O.OOe+00
4.13e+00
3.73e+00
l.OOe+02
ISCORS Technical Report 2004-03
6-2
Final, February 2005
-------
Table 6.1 Onsite Resident Scenario Total DSR Results
(mrem/yr per pCi/g) (continued)
Radio-
nuclide
Pa-231
Pb-210
Po-210
Pu-238
Pu-239
Ra-226
Ra-228
Sm-153
Sr-89
Sr-90
Th-228
Th-229
Th-230
Th-232
Tl-201
Tl-202
U-233
95% Peak
Total DSR
4.75e-02
1.88e-02
6.13e-03
1.23e-03
1.35e-03
1.94e-01
3.55e-02
9.93e-06
4.11e-04
3.23e-02
2.36e-02
5.71e-03
6.24e-02
5.28e-02
1.88e-05
3.45e-04
1.09e-03
Critical
Pathway(s)
Plant
Ingestion and
External
Meat
Meat
Plant and Soil
Ingestion
Plant and Soil
Ingestion
Radon *
External
External
Meat and
Plant
Ingestion
Meat and
Plant
Ingestion
External *
External
Radon
External
External
External
Meat and
Plant
Ingestion
Scaling Factors
1
l.OOe+00
l.OOe+00
1.59e-01
9.91e-01
9.99e-01
l.OOe+00
l.OOe+00
O.OOe+00
6.43e-03
9.40e-01
6.96e-01
l.OOe+00
l.OOe+00
l.OOe+00
O.OOe+00
l.OOe-09
9.93e-01
5
5.00e+00
4.83e+00
1.90e-01
4.86e+00
4.98e+00
5.00e+00
4.82e+00
O.OOe+00
6.47e-03
4.17e+00
1.92e+00
5.00e+00
5.01e+00
5.00e+00
O.OOe+00
l.OOe-09
4.89e+00
20
2.00e+01
1.56e+01
1.90e-01
1.82e+01
1.97e+01
2.00e+01
1.16e+01
O.OOe+00
6.47e-03
l.lle+01
2.29e+00
1.99e+01
2.01e+01
2.00e+01
O.OOe+00
l.OOe-09
1.86e+01
50
4.94e+01
2.65e+01
1.90e-01
3.99e+01
4.84e+01
4.98e+01
1.30e+01
O.OOe+00
6.47e-03
1.49e+01
2.29e+00
4.96e+01
5.06e+01
4.99e+01
O.OOe+00
l.OOe-09
4.20e+01
100
9.59e+01
3.19e+01
0.19
6.51e+01
9.36e+01
9.83e+01
1.30e+01
O.OOe+00
6.47e-03
1.56e+01
2.29e+00
9.85e+01
1.03e+02
9.94e+01
O.OOe+00
l.OOe-09
7.25e+01
Final, February 2005
6-3
ISCORS Technical Report 2004-03
-------
Table 6.1 Onsite Resident Scenario Total DSR Results
(mrem/yr per pCi/g) (continued)
Radio-
nuclide
U-234
U-235
U-238
Xe-131m
Zn-65
95% Peak
Total DSR
1.02e-03
2.53e-03
l.OOe-03
2.53e-06
2.07e-02
Critical
Pathway(s)
Meat and
Plant
Ingestion
External
External
External
External
Scaling Factors
1
9.90e-01
9.90e-01
9.90e-01
7.86e-13
3.54e-01
5
4.86e+00
4.86e+00
4.86e+00
7.86e-13
5.44e-01
20
1.81e+01
1.81e+01
1.81e+01
7.86e-13
5.47e-01
50
3.95e+01
3.95e+01
3.94e+01
7.86e-13
5.47e-01
100
6.42e+01
6.39e+01
6.35e+01
7.86e-13
5.47e-01
Table 6.2 Onsite Resident Scenario Indoor Radon DSR Results (mrem/yr per
pCi/g)
Radio-
nuclide
Ra-226
Th-228
95% Peak
Non-Rn
DSR
4.91e-02
2.14e-02
95% Peak Indoor Rn-only DSR
TEDE
(mrem/yr per pCi/g)
1.51e-01
2.01e-03
WL
(WL per pCi/g)
6.01e-06
4.83e-07
pCi/L
(pCi/L per pCi/g)
8.72e-04
0.0000208
Note:
The scaling factors in Table 6. 1 should be used to correct for the waiting time and multiple years of application.
ISCORS Technical Report 2004-03
6-4
Final, February 2005
-------
Table 6.3 Recreational User Scenario Total DSR Results (mrem/yr per pCi/g)
Radionuclide
Ac-227
Am-241
Be-7
C-14
Ce-141
Co-57
Co-60
Cr-51
Cs-134
Cs-137
Eu-154
Fe-59
H-3
1-125
1-131
In-111
K-40
La-138
Np-237
Pa-231
Pb-210
Po-210
Pu-238
Pu-239
Ra-226
Ra-228
Sm-153
Sr-89
Sr-90
Th-228
Th-229
Th-230
95% Peak
Total DSR
2.35E-03
1.82E-04
4.58E-05
9.76E-02
3.33E-05
2.76E-04
1.10E-02
1.49E-05
6.41E-03
2.86E-03
5.36E-03
9.67E-04
4.51E-06
3.33E-05
6.23E-05
3.30E-05
7.17E-04
5.60E-03
6.07E-01
1.05E-02
8.28E-04
4.15E-04
1.29E-04
1.45E-04
8.72E-03
7.37E-03
2.77E-06
1.51E-05
1.45E-03
6.51E-03
1.52E-03
3.05E-03
Critical Pathway(s)
External
Soil
External
Fish
External
External
External
External
External
External
External
External
Meat
Meat
External
External
External
External
Fish
External
Meat and Soil
Meat
Soil
Soil
External
External
External
Meat and External
Meat
External
External
External
Scaling Factor*
3 year waiting period
9.06E-01
9.95E-01
6.44E-07
l.OOE+00
7.09E-11
5.98E-02
6.66E-01
1.21E-12
3.63E-01
9.27E-01
7.87E-01
3.87E-08
8.62E-01
1.99E-06
O.OOE+00
O.OOE+00
6.20E-01
5.91E-01
8.55E-01
l.OOE+00
9.75E-01
4.08E-03
9.73E-01
l.OOE+00
l.OOE+00
l.OOE+00
O.OOE+00
2.74E-07
8.64E-01
3.37E-01
9.99E-01
l.OOE+00
Final, February 2005
6-5
ISCORS Technical Report 2004-03
-------
Table 6.3 Recreational User Scenario Total DSR Results (mrem/yr per
pCi/g) (continued)
Radionuclide
Th-232
Tl-201
Tl-202
U-233
U-234
U-235
U-238
Xe-131m
Zn-65
95% Peak Total
DSR
1.24E-02
5.01E-06
9.54E-05
1.96E-03
1.34E-03
2.15E-03
1.23E-03
8.19E-07
2.35E-03
Critical Pathway(s)
External
External
External
Fish
Soil
External
External
External
External
Scaling Factor*
3 year waiting period
l.OOE+00
O.OOE+00
1.02E-27
l.OOE+00
9.78E-01
9.79E-01
9.79E-01
O.OOE+00
4.43E-02
Note:
* Scaling factors calculated to be less than le-27 were rounded to zero and listed as O.OOe+00.
Table 6.4 Nearby Town Scenario Total DSR Results (mrem/yr per pCi/g)
Radio-
nuclide
Ac-227
Am-241
Be-7
C-14
Ce-141
Co-57
Co-60
Cr-51
Cs-134
Cs-137
Eu-154
Fe-59
H-3
95% Peak
Total DSR
5.94e-05
4.22e-06
6.43e-12
5.22e-07
7.12e-ll
2.98e-10
1.36e-08
1.806-11
2.84e-08
4.28e-08
7.50e-09
7.44e-10
5.32e-07
Critical
Pathway(s)
Inhalation
Inhalation
Inhalation
Inhalation
Inhalation
Meat
Ingestion
External
Meat
Ingestion
Meat
Ingestion
Meat
Ingestion and
External
External
Meat
Ingestion
Inhalation
Scaling Factors
1
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
5
4.68e+00
4.98e+00
1.36e+00
l.OOe+00
1.01 e+00
2.74e+00
4.91e+00
1.03e+00
3.67e+00
5.00e+00
4.97e+00
1.07e+00
l.OOe+00
20
1.49e+01
1.95e+01
1.36e+00
l.OOe+00
l.Ole+00
2.84e+00
1.53e+01
1.03 e+00
5.23e+00
1.98e+01
1. 80e+01
1.07e+00
l.OOe+00
50
2.51e+01
4.71e+01
1.36e+00
l.OOe+00
l.Ole+00
2.84e+00
1.93e+01
1.03 e+00
5.25e+00
4.65e+01
3.03e+01
1.07e+00
l.OOe+00
100
3.00e+01
8.89e+01
1.36e+00
l.OOe+00
l.Ole+00
2.84e+00
1.94e+01
1.03 e+00
5.25e+00
7.64e+01
3.28e+01
1.07e+00
l.OOe+00
ISCORS Technical Report 2004-03
6-6
Final, February 2005
-------
Table 6.4 Nearby Town Scenario Total DSR Results (mrem/yr per
pCi/g) (continued)
Radio-
nuclide
1-125
1-131
In-Ill
K-40
La-138
Np-237
Pa-231
Pb-210
Po-210
Pu-238
Pu-239
Ra-226
Ra-228
Sm-153
Sr-89
Sr-90
Th-228
Th-229
Th-230
Th-232
95% Peak
Total DSR
1.55e-08
2.12e-08
4.54e-ll
4.94e-10
2.69e-08
5.00e-06
5.30e-05
4.04e-07
9.68e-08
3.62e-06
3.95e-06
1.19e-04
1.96e-04
7.39e-ll
5.70e-10
5.76e-08
3.41e-04
1.92e-05
4.30e-05
3.51e-04
Critical
Pathway(s)
Meat
Ingestion
Meat
Ingestion
Plant and
Meat
Ingestion
External
Inhalation and
External
Inhalation
Inhalation
Inhalation
Inhalation
Inhalation
Inhalation
Radon
(outdoor)
Radon
(outdoor)
Plant and
Meat
Ingestion
Inhalation and
Meat
Ingestion
Meat
Ingestion
Radon
(outdoor)
Inhalation
Radon
(outdoor)
Radon
(outdoor)
Scaling Factors
1
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
5
1.05e+00
l.OOe+00
l.OOe+00
4.86e+00
3.95e+00
4.36e+00
5.00e+00
4.83e+00
1.35e+00
4.91e+00
4.99e+00
4.99e+00
4.82e+00
l.OOe+00
1.03e+00
4.98e+00
2.76e+00
5.00e+00
5.00e+00
5.00e+00
20
1.05e+00
l.OOe+00
l.OOe+00
1.48e+01
8.23e+00
1.14e+01
2.00e+01
1.59e+01
1.35e+00
1.84e+01
1.98e+01
1.99e+01
1.25e+01
l.OOe+00
1.03e+00
1.91e+01
3.29e+00
1.99e+01
1.99e+01
2.00e+01
50
1.05e+00
l.OOe+00
l.OOe+00
1.88e+01
9.12e+00
1.47e+01
4.95e+01
2.75e+01
1.35e+00
4.02e+01
4.84e+01
4.91e+01
1.43e+01
l.OOe+00
1.03e+00
3.75e+01
3.29e+00
4.97e+01
4.94e+01
4.98e+01
100
1.05e+00
l.OOe+00
l.OOe+00
1.90e+01
9.15e+00
1.52e+01
9.60e+01
3.38e+01
1.35e+00
6.59e+01
9.38e+01
9.64e+01
1.43e+01
l.OOe+00
1.03e+00
4.58e+01
3.29e+00
9.86e+01
9.75e+01
9.93e+01
Final, February 2005
6-7
ISCORS Technical Report 2004-03
-------
Table 6.4 Nearby Town Scenario Total DSR Results (mrem/yr per
pCi/g) (continued)
Radio-
nuclide
Tl-201
Tl-202
U-233
U-234
U-235
U-238
Xe-131m
Zn-65
95% Peak
Total DSR
4.49e-ll
2.19e-10
1. 50e-06
1. 15e-06
1.19e-06
1.04e-06
O.OOe+00
5.64e-09
Critical
Pathway(s)
Meat
Ingestion
Meat
Ingestion
Inhalation
Inhalation
Inhalation
Inhalation
Inhalation
Meat
Ingestion
Scaling Factors
1
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
5
l.OOe+00
1.01 e+00
4.92e+00
4.90e+00
4.91e+00
4.90e+00
l.OOe+00
2.43e+00
20
l.OOe+00
l.Ole+00
1.85e+01
1.83e+01
1.84e+01
1.83e+01
l.OOe+00
2.48e+00
50
l.OOe+00
l.Ole+00
4.13e+01
3.98e+01
4.06e+01
3.98e+01
l.OOe+00
2.48e+00
100
l.OOe+00
l.Ole+00
6.97e+01
6.45e+01
6.76e+01
6.44e+01
l.OOe+00
2.48e+00
6.3 LANDFILL NEIGHBOR SCENARIO
The following Tables give the 95% DSRs for the landfill neighbor scenarios. Several general
characteristics are of note. The Surface Impoundment calculations had higher DSRs than the
Municipal Solid Waste subscenario, as expected by the higher volume of sludge in the surface
impoundment. The radionuclides with the highest calculated DSRs are Np-237 and Th-232.
For several radionuclides, indoor radon was a significant fraction of the dose, and indoor radon
and non-radon components were calculated and are presented in a separate table.
Table 6.5 Landfill Neighbor Scenario (Municipal Solid Waste) Total DSR
Results (mrem/yr per pCi/g)
Radionuclide
Ac-227
Am-241
Be-7
C-14
Ce-141
Co-57
Co-60
Cr-51
Cs-134
Cs-137
95% Peak Total DSR
4.776-11
3.72e-05
O.OOe+00
4.81e-05
O.OOe+00
O.OOe+00
2.95e-30
O.OOe+00
O.OOe+00
2.76e-10
Critical Pathway(s)
Inhalation
Inhalation
N/A
Inhalation
N/A
N/A
Fish
N/A
N/A
Fish
ISCORS Technical Report 2004-03
Final, February 2005
-------
Table 6.5 Landfill Neighbor Scenario (Municipal Solid Waste) Total DSR
Results (mrem/yr per pCi/g) (continued)
Radionuclide
Eu-154
Fe-59
H-3
1-125
1-131
In-Ill
K-40
La-138
Np-237
Pa-231
Pb-210
Po-210
Pu-238
Pu-239
Ra-226
Ra-228
Sm-153
Sr-89
Sr-90
Th-228
Th-229
Th-230
Th-232
Tl-201
Tl-202
U-233
U-234
U-235
U-238
Xe-131m
Zn-65
95% Peak Total DSR
2.70e-22
O.OOe+00
3.01e-07
O.OOe+00
O.OOe+00
O.OOe+00
9.19e-06
7.72e-04
1.37e-01
2.44e-04
2.54e-10
O.OOe+00
5.10e-07
5.58e-05
1.95e-03
5.93e-27
O.OOe+00
O.OOe+00
3.06e-ll
O.OOe+00
2.25e-04
8.95e-04
7.93e-03
O.OOe+00
O.OOe+00
2.46e-05
7.32e-06
8.23e-06
3.71e-06
O.OOe+00
O.OOe+00
Critical Pathway(s)
Fish
N/A
Inhalation
N/A
N/A
N/A
External
Inhalation
Fish and Inhalation
Inhalation
Fish
N/A
Fish and Inhalation
Fish and Inhalation
Radon *
Fish
N/A
N/A
Fish
N/A
Fish and Inhalation
Radon *
Radon *
N/A
N/A
Fish and Inhalation
Radon and Inhalation *
Inhalation
Inhalation
N/A
N/A
Final, February 2005
6-9
ISCORS Technical Report 2004-03
-------
Table 6.6 Landfill Neighbor Scenario (MSW) Indoor Radon DSR Results
(mrem/yr per pCi/g)
Radio-
nuclide
Ra-226
Th-230
Th-232
U-234
95% Peak
Non-Rn DSR
7.50e-04
3.67e-04
2.41e-04
4.61e-06
95% Peak Indoor Rn-only DSR
TEDE(mrem/yr per
pCi/g)
3.76e-03
1.59e-03
3.26e-03
8.06e-06
WL
(WL per pCi/g)
1.48e-07
6.25e-08
6.47e-07
3.15e-10
pCi/L
(pCi/L per pCi/g)
1.93e-05
8.14e-06
3.64e-06
4.11e-08
Table 6.7 Landfill Neighbor Scenario (Surface Impoundment) Total DSR
Results (mrem/yr per pCi/g)
Radionuclide
Ac-227
Am-241
Be-7
C-14
Ce-141
Co-57
Co-60
Cr-51
Cs-134
Cs-137
Eu-154
Fe-59
H-3
1-125
1-131
In-111
K-40
La-138
Np-237
Pa-231
Pb-210
Po-210
95% Peak Total DSR
2.48e-09
1.90e-03
O.OOe+00
6.02e-03
O.OOe+00
O.OOe+00
1.68e-28
O.OOe+00
O.OOe+00
1.39e-08
1.42e-20
O.OOe+00
1.66e-05
O.OOe+00
O.OOe+00
O.OOe+00
4.26e-04
4.45e-02
1.18e+01
1.04e-02
1.52e-08
O.OOe+00
Critical Pathway(s)
Inhalation
Fish
N/A
Inhalation
N/A
N/A
Fish
N/A
N/A
Fish
Fish
N/A
Inhalation
N/A
N/A
N/A
External
Inhalation
Water and Plant (Irrigation)
Inhalation
Fish
N/A
ISCORS Technical Report 2004-03
6-10
Final, February 2005
-------
Table 6.7 Landfill Neighbor Scenario (Surface Impoundment) Total DSR
Results (mrem/yr per pCi/g) (continued)
Radionuclide
Pu-238
Pu-239
Ra-226
Ra-228
Sm-153
Sr-89
Sr-90
Th-228
Th-229
Th-230
Th-232
Tl-201
Tl-202
U-233
U-234
U-235
U-238
Xe-131m
Zn-65
95% Peak Total DSR
2.52e-06
2.37e-03
8.88e-02
3.24e-25
O.OOe+00
O.OOe+00
1.58e-09
O.OOe+00
9.45e-03
4.32e-02
4.06e-01
O.OOe+00
O.OOe+00
9.33e-04
3.41e-04
3.36e-04
1.38e-04
O.OOe+00
O.OOe+00
Critical Pathway(s)
Fish and Inhalation
Fish and Inhalation
Radon *
Fish
N/A
N/A
Fish
N/A
Fish and Inhalation
Radon *
Radon *
N/A
N/A
Fish and Inhalation
Radon *
Inhalation
Inhalation
N/A
N/A
Table 6.8 Landfill Neighbor Scenario (Surface Impoundment) Indoor Radon
DSR Results (mrem/yr per pCi/g)
Radio-
nuclide
Ra-226
Th-230
Th-232
U-234
95% Peak
Non-Rn DSR
2.66e-02
1.41e-02
l.OOe-02
1.99e-04
95% Peak Indoor Rn-only DSR
TEDE
(mrem/yr per pCi/g)
1.93e-01
8.47e-02
1.68e-01
4.28e-04
WL
(WL per pCi/g)
7.57e-06
3.32e-06
3.33e-05
1.68e-08
pCi/L
(pCi/L per pCi/g)
9.85e-04
4.32e-04
1.87e-04
2.19e-06
Final, February 2005
6-11
ISCORS Technical Report 2004-03
-------
6.4 INCINERATOR NEIGHBOR SCENARIO
Table 6.9 gives the 95% DSRs for the incinerator neighbor scenario. These values have been
"decay corrected" to translated instantaneous dose rates to annual doses. The highest DSRs for
the incinerator neighbor scenario were Ac-227 and the long-lived radionuclides Pa-231, Th-229,
and Th-232.
Table 6.9 Incinerator Neighbor Scenario Total DSR Results
(mrem/yr per pCi/g)
Radionuclide
Ac-227
Am-241
Be-7
C-14
Ce-141
Co-57
Co-60
Cr-51
Cs-134
Cs-137
Eu-154
Fe-59
H-3
1-125
1-131
In-111
K-40
La-138
Np-237
Pa-23 1
Pb-210
Po-210
Pu-238
Pu-239
Ra-226
Ra-228
Sm-153
95% Peak Total DSR
1.18e+01
7.99e-01
1.09e-06
3.99e-07
3.02e-06
1.02e-04
7.97e-03
8.78e-07
6.69e-03
1.43e-02
4.34e-03
3.54e-04
3.17e-06
6.99e-02
1.31e-02
2.42e-07
4.81e-04
1.06e-02
9.93e-01
2.35e+00
4.74e-02
1.64e-02
7.04e-01
7.74e-01
8.80e-02
2.53e-02
2.03e-07
Critical Pathway(s)
Inhalation
Inhalation
External
Inhalation
Inhalation
Meat Ingestion
External
Meat Ingestion
Meat Ingestion
Meat Ingestion and External
External
Meat Ingestion
Inhalation
Meat Ingestion
Meat Ingestion
Plant and Meat Ingestion
External
Inhalation and External
Inhalation
Inhalation
Inhalation and Plant Ingestion
Inhalation
Inhalation
Inhalation
Inhalation, External, and Plant
Inhalation
Plant and Meat Ingestion
ISCORS Technical Report 2004-03
6-12
Final, February 2005
-------
Table 6.9 Incinerator Neighbor Scenario Total DSR Results
(mrem/yr per pCi/g) (continued)
Radionuclide
Sr-89
Sr-90
Th-228
Th-229
Th-230
Th-232
Tl-201
Tl-202
U-233
U-234
U-235
U-238
Xe-131m
Zn-65
95% Peak Total DSR
4.70e-05
3.86e-02
5.23e-01
3.87e+00
5.85e-01
2.97e+00
2.31e-07
4.74e-06
2.43e-01
2.37e-01
2.22e-01
2.12e-01
O.OOe+00
2.28e-03
Critical Pathway(s)
Inhalation and Meat Ingestion
Meat Ingestion
Inhalation
Inhalation
Inhalation
Inhalation
Meat Ingestion
Meat Ingestion
Inhalation
Inhalation
Inhalation
Inhalation
Inhalation
Meat Ingestion
6.5 OCCUPATIONAL SCENARIOS
6.5.1 SLUDGE APPLICATION WORKER
For the Sludge Application Worker scenario, the highest DSRs were due to Ac-227, Co-60,
Ra-226, and Th-232. For multiple years of application, Th-232 has the highest DSR because of
the importance of daughter ingrowth.
Table 6.10 Sludge Application Worker Scenario Total DSR Results (mrem/yr
per pCi/g)
Radio-
nuclide
Ac-227
Am-241
Be-7
C-14
Ce-141
Co-57
95% Peak
Total
DSR
7.62e-03
4.42e-04
4.00e-05
1.71e-07
2.60e-05
2.05e-04
Critical
Pathway(s)
Inhalation
Inhalation
External
Inhalation
External
External
Scaling Factors
1
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
5
4.68e+00
4.98e+00
l.Ole+00
l.OOe+00
l.OOe+00
1.63e+00
20
1.48e+01
1.95e+01
l.Ole+00
l.OOe+00
l.OOe+00
1.64e+00
50
2.47e+01
4.71e+01
l.Ole+00
l.OOe+00
l.OOe+00
1.64e+00
100
2.94e+01
8.88e+01
l.Ole+00
l.OOe+00
l.OOe+00
1.64e+00
Final, February 2005
6-13
ISCORS Technical Report 2004-03
-------
Table 6.10 Sludge Application Worker Scenario Total DSR Results (mrem/yr
per pCi/g) (continued)
Radio-
nuclide
Co-60
Cr-51
Cs-134
Cs-137
Eu-154
Fe-59
H-3
1-125
1-131
In-Ill
K-40
La-138
Np-237
Pa-231
Pb-210
Po-210
Pu-238
Pu-239
Ra-226
Ra-228
Sm-153
Sr-89
Sr-90
Th-228
Th-229
Th-230
Th-232
Tl-201
Tl-202
U-233
U-234
95% Peak
Total
DSR
9.87e-03
1.27e-05
5.35e-03
2.25e-03
4.73e-03
8.81e-04
3.36e-07
2.05e-07
4.90e-05
2.73e-05
6.51e-04
5.08e-03
1.17e-03
6.41e-03
2.34e-05
4.16e-06
3.75e-04
4.16e-04
7.41e-03
6.74e-03
1.78e-06
1.15e-06
1.67e-05
6.23e-03
3.15e-03
2.63e-03
1.25e-02
3.28e-06
8.03e-05
1.99e-04
1.23e-04
Critical
Pathway(s)
External
External
External
External
External
External
Inhalation
External
External
External
External
External
External
Inhalation
Inhalation
Inhalation
Inhalation
Inhalation
External
External
External
External
External
External
External
External
External
External
External
Inhalation
Inhalation
Scaling Factors
1
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
5
3.88e+00
l.OOe+00
2.84e+00
4.75e+00
4.29e+00
l.OOe+00
l.OOe+00
l.Ole+00
l.OOe+00
l.OOe+00
3.39e+00
3.28e+00
4.35e+00
6.72e+00
5.26e+00
1.19e+00
4.91e+00
4.99e+00
4.99e+00
6.25e+00
l.OOe+00
l.Ole+00
4.43e+00
2.75e+00
5.00e+00
5.30e+00
1.41e+01
l.OOe+00
l.OOe+00
4.94e+00
4.90e+00
20
7.32e+00
l.OOe+00
3.47e+00
1.58e+01
1.04e+01
l.OOe+00
l.OOe+00
l.Ole+00
l.OOe+00
l.OOe+00
5.06e+00
4.67e+00
1.10e+01
4.73e+01
1.73e+01
1.19e+00
1.84e+01
1.98e+01
1.99e+01
1.67e+01
l.OOe+00
l.Ole+00
1.18e+01
3.29e+00
1.99e+01
2.57e+01
1.63e+02
l.OOe+00
l.OOe+00
1.89e+01
1.83e+01
50
7.82e+00
l.OOe+00
3.48e+00
2.84e+01
1.27e+01
l.OOe+00
l.OOe+00
l.Ole+00
l.OOe+00
l.OOe+00
5.13e+00
4.71e+00
1.40e+01
1.78e+02
2.94e+01
1.19e+00
4.03e+01
4.84e+01
4.91e+01
1.88e+01
l.OOe+00
l.Ole+00
1.58e+01
3.29e+00
4.96e+01
8.61e+01
5.81e+02
l.OOe+00
l.OOe+00
4.37e+01
3.98e+01
100
7.82e+00
l.OOe+00
3.48e+00
3.62e+01
1.30e+01
l.OOe+00
l.OOe+00
l.Ole+00
l.OOe+00
l.OOe+00
5.13e+00
4.71e+00
1.44e+01
4.30e+02
3.55e+01
1.19e+00
6.57e+01
9.37e+01
9.63e+01
1.89e+01
l.OOe+00
l.Ole+00
1.65e+01
3.29e+00
9.85e+01
2.43e+02
1.29e+03
l.OOe+00
l.OOe+00
7.78e+01
6.43e+01
ISCORS Technical Report 2004-03
6-14
Final, February 2005
-------
Table 6.10 Sludge Application Worker Scenario Total DSR Results (mrem/yr
per pCi/g) (continued)
Radio-
nuclide
U-235
U-238
Xe-131m
Zn-65
95% Peak
Total
DSR
6.08e-04
1.94e-04
4.35e-07
1.52e-03
Critical
Pathway(s)
External
External
External
External
Scaling Factors
1
l.OOe+00
l.OOe+00
l.OOe+00
l.OOe+00
5
4.90e+00
4.90e+00
l.OOe+00
1.54e+00
20
1.83e+01
1.82e+01
l.OOe+00
1.55e+00
50
3.98e+01
3.97e+01
l.OOe+00
1.55e+00
100
6.45e+01
6.41e+01
l.OOe+00
1.55e+00
6.5.2 PUBLICLY OWNED TREATMENT WORKS WORKER
SCENARIOS
For the POTW Worker Scenarios, the Loading sub scenario had the highest DSRs, and the
radionuclides Ra-226 and Th-228 had by far the highest DSRs in that subscenario. In the case of
the Sampling Worker, even if samples were taken every hour for 2,000 hours a year, the DSRs
would be significantly smaller than those for the Loading subscenario. Similarly, even in the
case where the Transport Worker is in proximity to sewage sludge for 2,000 hours a year, the
Loading subscenario would have the highest DSRs. Indoor radon contributed a significant
portion of the dose for Ra-226 and Th-228 in the Transport and Loading subscenarios. For these
scenarios, radon doses are also presented separately.
The computed DSRs for radium-226 and Th-228 for the POTW loading worker, which are
dominated by radon contributions, depend strongly on the room air exchange rate and the height
of the room. For this present report, nine combinations of building height and air exchange rate
were used (see discussion in Section 4.7.3), with building heights of 2 m, 4 m, and 6 m, and air
exchange rates of 1.5, 3, and 5 per hour. These parameters primarily affect the doses from
inhalation of radon progeny. The impact of changes in air exchange rate and room height can be
seen in Table 6.14b, which shows DSRs for the nine combinations of parameters.
Final, February 2005
6-15
ISCORS Technical Report 2004-03
-------
Table 6.11 POTW Sampling Worker Scenario Total DSR Results (mrem/yr per
pCi/g)
Radionuclide
Ac-227
Am-241
Be-7
C-14
Ce-141
Co-57
Co-60
Cr-51
Cs-134
Cs-137
Eu-154
Fe-59
H-3
1-125
1-131
In-111
K-40
La-138
Np-237
Pa-231
Pb-210
Peak Total DSR
3.80e-09
4.05e-10
5.08e-10
6.03e-10
7.54e-10
1.17e-09
2.39e-08
3.23e-10
1.59e-08
5.79e-09
1.21e-08
1.14e-08
O.OOe+00
7.63e-10
3.87e-09
4.13e-09
1.45e-09
1.18e-08
2.49e-09
5.61e-10
5.62e-ll
ladionuclide
Po-210
Pu-238
Pu-239
Ra-226
Ra-228
Sm-153
Sr-89
Sr-90
Th-228
Th-229
Th-230
Th-232
Tl-201
Tl-202
U-233
U-234
U-235
U-238
Xe-131m
Zn-65
Peak Total DSR
8.60e-14
2.63e-ll
1.08e-ll
1.61e-08
9.19e-09
6.84e-10
8.45e-13
2.47e-14
1.38e-08
3.42e-09
1.88e-ll
1.68e-ll
9.30e-10
4.78e-09
1.74e-ll
2.16e-ll
1.82e-09
2.54e-10
2.82e-10
5.68e-09
Notes:
Only External pathway was evaluated in this subscenario. In addition, only deterministic calculations were
performed.
ISCORS Technical Report 2004-03
6-16
Final, February 2005
-------
Table 6.12 POTW Intra-POTW Transport Worker Scenario Total DSR Results
(mrem/yr per pCi/g)
Radionuclide
Ac-227
Am-241
Be-7
C-14
Ce-141
Co-57
Co-60
Cr-51
Cs-134
Cs-137
Eu-154
Fe-59
H-3
1-125
1-131
In-111
K-40
La-138
Np-237
Pa-231
Pb-210
Po-210
Pu-238
Pu-239
Ra-226
Ra-228
Sm-153
Sr-89
Sr-90
Th-228
Th-229
Th-230
Peak Total DSR
4.20e-07
3.84e-08
5.72e-08
7.13e-08
8.57e-08
1.30e-07
2.71e-06
3.57e-08
1.80e-06
6.54e-07
1.38e-06
1.30e-06
O.OOe+00
8.15e-08
4.35e-07
4.59e-07
1.65e-07
1.34e-06
2.67e-07
5.34e-08
3.78e-09
9.73e-12
1.61e-09
6.61e-10
3.29e-06
1.04e-06
7.92e-08
9.57e-ll
1.50e-12
6.74e-05
3.76e-07
1.15e-09
Critical Pathway(s)
External
External
External
External
External
External
External
External
External
External
External
External
External
External
External
External
External
External
External
External
External
External
External
External
External and Radon *
External
External
External
External
External *
External
External
Final, February 2005
6-17
ISCORS Technical Report 2004-03
-------
Table 6.12 POTW Intra-POTW Transport Worker Scenario Total DSR Results
(mrem/yr per pCi/g) (continued)
Radionuclide
Th-232
Tl-201
Tl-202
U-233
U-234
U-235
U-238
Xe-131m
Zn-65
Peak Total DSR
9.37e-10
1.04e-07
5.39e-07
1.17e-09
1.30e-09
1.91e-07
2.69e-08
3.08e-08
6.43e-07
Critical Pathway(s)
External
External
External
External
External
External
External
External
External
Note: .
Only deterministic calculations were performed for this subscenario
Table 6.13 POTW Intra-POTW Transport Worker Scenario Indoor Radon
DSR Results (mrem/yr per pCi/g)
Radionuclide
Ra-226
Th-228
Peak Non-Rn DSR
1.83e-06
1.57e-06
Peak Indoor Rn-only DSR
TEDE
(mrem/yr per pCi/g)
1.46e-06
6.58e-05
WL
(WL per pCi/g)
3.30e-07
7.63e-05
pCi/L
(PCi/L per pCi/g)
2.00e-04
3.87e-02
Note:
Only deterministic calculations were performed for this subscenario.
ISCORS Technical Report 2004-03
6-18
Final, February 2005
-------
Table 6.14a POTW Biosolids Loading Worker Scenario Total DSR Results
(mrem/yr per pCi/g)
Radionuclide
Ac-227
Am-241
Be-7
C-14
Ce-141
Co-57
Co-60
Cr-51
Cs-134
Cs-137
Eu-154
Fe-59
H-3
1-125
1-131
In-111
K-40
La-138
Np-237
Pa-231
Pb-210
Po-210
Pu-238
Pu-239
Ra-226
Ra-226
Ra-228
Sm-153
Sr-89
Sr-90
Th-228
Th-229
95% Peak Total DSR
4.05E-01
2.35E-02
1.23E-02
5.60E-07
1.25E-02
1.92E-02
7.00E-01
7.40E-03
4.07E-01
1.46E-01
3.32E-01
3.31E-01
1.33E-03
6.00E-04
9.20E-02
8.05E-02
4.53E-02
3.46E-01
2.89E-02
8.05E-02
1.33E-03
4.35E-04
1.80E-02
2.38E-02
5.9E-01-2.7E+00*
5.9E-01-2.7E+00*
2.59E-01
5.80E-03
3.95E-04
1.05E-03
2.2E+00-1.8E+01*
1.74E-01
Critical Pathway(s)
Inhalation
Inhalation
External
External
External
External
External
External
External
External
External
External
Inhalation
External
External
External
External
External
Inhalation
Inhalation and External
Inhalation and External
Inhalation
Inhalation
Inhalation
Radon
Radon
External
External
External
External
Radon
External
Final, February 2005
6-19
ISCORS Technical Report 2004-03
-------
Table 6.14a POTW Biosolids Loading Worker Scenario Total DSR Results
(mrem/yr per pCi/g) (continued)
Th-230
Th-232
Tl-201
Tl-202
U-233
U-234
U-235
U-238
Xe-131m
Zn-65
1.68E-02
8.35E-02
1.01E-02
1.05E-01
7.55E-03
6.15E-03
3.68E-02
1.13E-02
8.75E-04
1.60E-01
Inhalation
Inhalation
External
External
Inhalation
Inhalation
External
External
External
External
Note:
* Range represents results from the nine combinations of air exchange rate and room height (see Section 4.7.3).
Individual results are shown in Table 6.14b.
Table 6.14b POTW Biosolids Loading Worker Scenario Total DSR Results
(mrem/yr per pCi/g) for Ra-226 and Th-228
Air exchange rate
(h1)
1.5
3
5
Room height
(m)
2
4
6
2
4
6
2
4
6
95% Peak total DSR (mrem/y per pCi/g)
Ra-226
2.7
1.6
1.2
1.2
0.85
0.73
0.79
0.64
0.59
Th-228
18
9.4
6.4
9.3
4.9
3.4
5.6
3.0
2.2
ISCORS Technical Report 2004-03
6-20
Final, February 2005
-------
Table 6.15 POTW Biosolids Loading Worker Scenario Indoor Radon DSR Results
(mrem.yr per pCi/g)
Radio-nuclide
Ra-226
Th-228
95% Peak
Non-Rn DSR
0.48
0.45
95% Peak Indoor Rn-only DSR*
TEDE
(mrem/yr per pCi/g)
0.10-2.2
1.7-18
WL
(WLperpCi/g)
2.3E-5 - 5.0E-4
1.9E-3-2.0E-2
pCi/L
(pCi/yr per pCi/g)
0.026-0.32
2.5-11
Note:
* Range represents results from the nine combinations of air exchange rate and room height (see Section 4.7.3).
Final, February 2005
6-21
ISCORS Technical Report 2004-03
-------
-------
7 RADIATION DOSES CORRESPONDING TO THE
RESULTS OF THE ISCORS PUBLICLY OWNED
TREATMENT WORKS SURVEY
7.1 RADIATION DOSES CORRESPONDING TO SURVEY SAMPLE
ACTIVITIES
Given a measured activity in a sludge or ash sample taken from a real POTW, the
Dose-to-Source Ratios (DSRs) calculated in Chapter 6 can be used to estimate the corresponding
dose that potentially would be imparted to members of the critical population group for any of
the seven hypothetical scenarios that have been constructed.
For a given sample that yields the set of measured activities, {Ar}, with the radionuclides
parameterized by r, and in considering scenario s, one can approximate the total peak dose as
shown in Equation 7.1,
D. =
(7>1)
where {DSRre} are the 95-th percentile Dose-to-Source Ratios for these radionuclides and for
scenario s. Equation (7.1) would be strictly valid only if the dose peaks for all the radionuclides
occurred at the same time, which they do not—so it may somewhat slightly overestimate the
total dose; but it is commonly the case that one or a few radionuclides dominate the estimated
total dose, so deviations from the equation are likely not to be significant.
With the procedure of Equation (7.1) and the selection of the 95% DSRs, and for each scenario,
a total (all radionuclides) dose was calculated for every sludge and ash sample11 from the
ISCORS national survey (REF). With N survey samples, the N values of dose found for each
scenario defines a distribution, and it is the median (50%) and 95% values of these distributions
of calculated doses that are presented in Table 7.1, and are presented with and without any
significant indoor Radon component. The separate calculations of doses and concentrations with
indoor Radon only are presented in Table 7.2.
The estimated doses included in this report apply only to the critical population group related to
each scenario. While coarse upper-bound calculations for general populations may be feasible,
more realistic estimates would require careful assessments of demographic and other issues, such
as the rates at which farmlands are being developed and town borders are expanding. There has
been no attempt here to undertake such a study, however, nor to compute any population doses.
11 For all the scenarios but the landfill neighbor, the sewage sludge samples from the survey are used for the source
term. For the landfill neighbor scenario, two different source terms are used: The municipal solid waste (MSW)
subscenario uses both sewage sludge and ash samples, since municipal solid waste landfills tend to contain both
materials; the source term for the surface impoundment subscenario, by contrast, considers only sludge samples.
Final, February 2005 7-1 ISCORS Technical Report 2004-03
-------
Table 7.1 Calculated Total Peak Dose (Total Effective Dose Equivalent-TEDE)
from Survey Samples: Summary Results With and Without Indoor
Radon Contribution
Scenario
SI - Onsite
Resident
S2 - Recreational
S3 - Nearby Town
S4 - Landfill
S5 - Incinerator
S6 - Sludge
Application
Worker
S7 - POTW
Workers
Subscenario
1 yr of appl.
5
20
50
100
N/A
1 yr of appl.
5
20
50
100
MSW - Sludge
MSW - Ash
Impoundment
N/A
1 yr of appl.
5
20
50
100
Sampling
(mrem/sample)
Transport (mrem/hr)
Loading
Median sample
TEDE
0.5
2.5
9.2
22
42
0.04
6.4e-04
2.8e-03
8.5e-03
0.017
0.029
4.6e-03
0.014
0.21
1.2
0.032
0.16
0.57
1.3
2.3
9.6e-08
4.6e-05
3.8-172
TEDE
w/o Rn
0.2
1
3.4
7.2
13
~
~
~
~
~
~
1.6e-03
3.1e-03
0.062
~
~
~
~
~
~
~
l.le-05
2.7
95% sample
TEDE
3
14
55
130
260
0.22
3.2e-03
0.014
0.045
0.094
0.17
0.027
0.041
1.2
7.7
0.15
0.77
3
7.4
15
4.9e-07
1.9e-04
17-702
TEDE
w/o Rn
1
4.9
16
37
69
~
~
~
~
~
~
0.01
0.014
0.36
~
~
~
~
~
~
~
5.6e-05
13
Dominant
Radionuclide(s)
[pathways]
Ra-226 [indoor radon]
Ra-226 [indoor radon]
Ra-226 [indoor radon]
Ra-226 [indoor radon]
Ra-226 [indoor radon]
Ra-226 [external]
Ra-226 [outdoor radon]
Ra-226 [outdoor radon]
Ra-226 [outdoor radon]
Ra-226 [outdoor radon]
Ra-226 [outdoor radon]
Ra-226 [indoor radon]
Ra-226 [indoor radon]
Ra-226 [indoor radon]
multiple [multiple]
Ra-226 [external]
Ra-226 [external]
Ra-226 [external]
Ra-226 [external]
Ra-226 [external]
Ra-226 [external]
Th-228 [indoor radon,
external]
Ra-226, Th-228 [indoor
Rn]
Notes:
All values rounded to two significant figures. Note that 95% DSRs are used in all total peak dose calculations.
A "-" denotes that indoor radon was not separately calculated.
1 There are very few land application sites in the country that are known to have applied sewage sludge
annually for more than 20 years; the 50- and 100-year computations were included for the information of
POTW operators in their consideration of future sludge management practices.
2 Range represents results from the nine combinations of air exchange rate and room height (see Sections 4.7.3
and 7. 5 below).
ISCORS Technical Report 2004-03
7-2
Final, February 2005
-------
Table 7.2 Calculated Total Peak Radon Doses and Concentrations from Survey
Samples
Scenario
SI - Onsite
Resident
S4 - Landfill
S7 - POTW
Workers
Subscenario
1 yr of appl.
5
20
50
100
MSW - Sludge
MSW - Ash
Impoundment
Transport
Loading
Median sample
TEDE
Rn only
0.3
1.5
6
15
30
9.1e-03
0.018
0.47
3.4e-05
92
WLRn
only
1.3e-05
6.2e-05
2.4e-04
6.0e-04
1.2e-03
3.4e-07
l.Oe-06
2.5e-05
3.4e-05
0.028
pCi/L
Rn-222
1.7e-03
8.7e-03
0.035
0.087
0.17
3.9e-05
7.2e-05
2.0e-03
4.0e-04
3
pCi/L
Rn-220
8.3e-08
2.3e-07
2.7e-07
2.7e-07
2.7e-07
0
1.8e-06
0
0.017
10
95% sample
TEDE
Rn only
2
9.8
39
98
193
0.057
0.078
2.9
1.5e-04
390
WLRn
only
7.9e-05
3.9e-04
1.6e-03
3.9e-03
7.7e-03
2.1e-06
3.1e-06
1.5e-04
1.6e-04
0.12
pCi/L
Rn-222
0.011
0.057
0.23
0.56
1.1
2.6e-04
3.5e-04
0.013
2.6e-03
19
pCi/L
Rn-220
4.0e-07
l.le-06
1.3e-06
1.3e-06
1.3e-06
1.5e-06
3.4e-06
7.5e-05
0.081
51
* Range represents results from the nine combinations of air exchange rate and room height (see Sections 4.73
and 7.5, below).
7.2 CALCULATED DOSES FOR LAND APPLICATION SCENARIOS
As is evident from Table 7.1, the only non-worker scenario of any potential concern is the onsite
resident. The primary contributing radionuclides here are from NORM sources, and the critical
pathway is indoor radon from Ra-226. Radon and its daughters are responsible for 65%-75% of
the calculated doses, and gamma ray exposure from radium for another 20%. The radon-specific
calculations are in Table 7.2.
The parameter values selected for the calculation tend in general to be somewhat conservative.
The air exchange rate is taken to be relatively low, for example, especially in view of the fact
that many houses in high-radon areas have radon mitigation systems in place. The foundation
slab for the onsite resident's house was laid down directly on the soil surface with no excavation;
in practice, soils are usually removed down to the natural and undisturbed level, and any
significant excavation of the ground surface prior to building the house foundation (whether a
slab or a basement) will largely eliminate the radon dose. On the other hand, construction of an
unventilated crawl space foundation could lead to an increased radon dose. In general, however,
the calculated doses probably overestimate the actual radon doses in most residences.
For some long-lived radionuclides (in particular, radium-226), doses scale more or less linearly
with number of applications. This should be borne in mind especially when interpreting the
doses to the on-site resident for 100 applications or even 50 applications; these two
sub-scenarios were included in the modeling for consistency with the technical support for the
40 CFR Part 503 rule, and to examine trends in the calculations. No data has been found to
support the proposition that sludge might, or might not, be applied over such long periods at a
significant number of farms.
Final, February 2005
7-3
ISCORS Technical Report 2004-03
-------
Short lived radioisotopes such as iodine-131 are generally not of concern, by contrast, even when
animals graze and people consume the resulting milk. Most sludge is classified as Class B, in
accord with 40 CFR 503, and therefore required to have 30 day waiting period prior to sale and
application; only rarely is sludge treated to destroy pathogens and released as Class A sludge
without a waiting period.
7.3 CALCULATED DOSES FOR LANDFILL/IMPOUNDMENT
NEIGHBOR SCENARIO
As expected, the calculated doses from the Surface Impoundment subscenario was greater than
those from the Municipal Solid Waste landfill. The dominant radionuclide was Ra-226, and the
dominant pathway the radon pathway in all cases. However, the doses even at the 95th percentile
sample level were small, with the largest being about 1.5 mrem/year.
7.4 CALCULATED DOSES FOR PUBLICLY OWNED TREATMENT
WORKS INCINERATOR NEIGHBOR SCENARIO
The doses from the incinerator neighbor were not dominated by any one radionuclide. The
radionuclides Ac-227,1-125,1-131, Pb-210, Ra-226, Th-228, Th-232, U-234, and U-238
commonly contributed to the total doses. The dominant pathways tended to be inhalation and
meat consumption. At the 95th percentile sample level, the doses were less then 10 mrem/yr.
7.5 CALCULATED DOSES FOR PUBLICLY OWNED TREATMENT
WORKS SLUDGE/ASH WORKER SCENARIOS
There is considerable variability in POTW facility design, operation and sludge management, as
discussed in Chapter 4, and this is reflected in the selection of parameter distributions.
The critical worker scenario is that of the POTW Loading Worker. NORM is again the primary
source, and indoor radon is dominant, with Rn-220 and Rn-222 and their daughters responsible
for 94% of the total calculated dose. Table 7.1 includes the total dose with and without the
indoor Radon pathway. Table 7.2 presents the results with only radon pathway.
As with the Onsite Resident, however, the radon dose for this subscenario is highly dependent on
the particular characteristics of the POTW site, in this case the room where sludge is being
managed (e.g., dried, packaged, and loaded). A sensitivity analysis with building parameter
values determined for two real POTWs yielded doses from the radon pathway that were
generally lower than those calculated from the default probability distributions. Parameters that
were particularly sensitive included the bulk density and volume of the sludge, and the volume
and air exchange rate of the room.
Because of the site-specific nature of POTW operations, below are provided fitting functions for
calculating DSRs based on the above four site-specific parameters. These may be helpful for
rough estimates potential doses at particular POTWs. However, it should be emphasized that
more detailed site-specific assessments may be necessary for additional accuracy.
ISCORS Technical Report 2004-03 7-4 Final, February 2005
-------
Using a baseline exposure time of 1,000 hours per year, the following two expressions
(Equations 7.2 and 7.3) are for the DSRs for Ra-226 and Th-228 (in mrem/yr per pCi/g) in terms
of these four parameters alone and with all others held constant:12
DSRRa.226 • -0.5 + 41.5 rsludge^sludge x (texp /1000 hours)/[ (0.008 + •/) x (7.2)
(2.69/7room-°-77+%-)Froom] ,
g • -0.45 + 2649 rsludge ^sludge x (texp /1000 hours)/[ (45 + •/) x (7.3)
Cl 25 h -°-77 + *i\V 1
*• •<*•••> '' " •>
room
These expressions reproduce RESRAD-BUILD runs to within about 10%. 13 The first term in
each equation represents external exposure, and the second is for indoor radon exposure. Note
that '/is the room air exchange rate in exchanges per hour; rsludge the bulk density of the sludge
in grams per cubic cm; Fsludge the total volume of sludge in the room in cubic meters; Froom the
total volume of the room in cubic meters; hmom the height of the room in meters; ^4sludge the surface
area of the pile of sludge in the room in square meters; and texp is the exposure time (working
time per year) in hours. The derivation of these fitting formulae, and additional discussion and
motivation for their functional form, are contained in Appendix D.
For radon, the relationships among dose, progeny concentrations in working levels (WL), and
exposures in working level months (WLM) are described in Appendix D.
7.6 UNCERTAINTY AND VARIABILITY IN CALCULATED DOSES
It should be borne in mind that there are uncertainties and variabilities in the DSRs, arising in the
construction of the hypothetical scenarios, in the selection of the modeling parameter values and
distribution, and in the model itself. There are also, of course, errors in the measured survey
activities used in the source terms. Of these, only the parameter uncertainty and variability and
the source variability are well quantified.
Table 7.3 summarizes the relative importance of parameter uncertainty /variability and source
variability (which greatly exceeds source uncertainty) with respect to the calculated doses. As
with Table 5-2, it presents the ratio of the 95-th percentile DSR to the 5% DSR. In the case of
parameter uncertainty /variability, the 95% sample dose was calculated using both 95% and 5%
DSRs, and this ratio captures the dose range due to changes in model parameters. In the case of
12 It is assumed that even as the area of the sludge pile increases, the worker stands at its edge. The radon
contribution to the Th-228 dose depends only on the area of the pile and not the volume because the Rn-220
half-life is so short (< 1 minute) that it can escape into the air via diffusion only when produced from Th-228
parents near the surface of the pile. Rn-222 from Ra-226 has a much longer half-life (almost 4 days) and can
escape from any point inside a reasonably sized pile.
13 For instance, for ••= 4 per hour, rsludge = 1 g/cm3, ^sludge = 6900 m2, Fsludge = 13,800 m3, Froom = 72,000 m3, the
worker standing at the edge of a circular pile, and 1 pCi/g each of Ra-226 and Th-228 in the sludge,
RESRAD-BUILD gives a total dose of 2.6 mrem/yr, whereas the approximate expression above gives
2.3 mrem/yr, a difference of only 12%.
Final, February 2005 7-5 ISCORS Technical Report 2004-03
-------
source uncertainty, the ratio was taken between the 95% sample dose and 5% sample dose, for a
fixed 95% DSR, thereby measuring the dose range due to different sludge and ash sample
sources. Clearly, the source variability is a significantly greater cause of variance than the
parameter uncertainty. Only in the cases of the POTW loading scenario are the magnitudes of
parameter uncertainty and variability (for Ra-226 and Th-228) and the source variability
comparable. In general, the source variability is greater by a factor of at least 10 or more.
Table 7.3 Source Variability and Parameter Variability and Uncertainty in
Calculated Survey Sample Doses
Scenario
Onsite
Resident
Recreational
User
Residents of
Nearby Town
Landfill
Neighbor
POTW
Incinerator
Neighbor
Subscenario
1 yr of appl.
5
20
50
100
N/A
1 yr of appl.
5
20
50
100
MSW (Sludge)
MSW (Ash)
Impoundment
50-year
operational life
Source Variability:
Ratio of 95% survey
dose to 5% survey dose,
both using 95% DSRs
43
46
58
87
100
31
21
25
32
40
59
130
10
130
36
Parameter Uncertainty &
Variability:
Ratio of 95% survey dose
using 95% DSRs to 95%
survey dose using 5% DSRs
1.3
1.3
1.2
1.2
1.2
1.5
1.08
1.09
1.08
1.03
1.04
1.6
1.7
1.4
2.3
ISCORS Technical Report 2004-03
7-6
Final, February 2005
-------
Table 7.3 Source Variability and Parameter Variability and Uncertainty in
Calculated Survey Sample Doses (continued)
Sludge
Application
Worker
POTW
Workers
1 yr of appl.
5
20
50
100
Sampling
Transport
Loading
22
24
36
60
94
22
14
16-19*
1.09
1.07
1.2
1.3
1.3
-
-
1.04-2.0*
Note:
* Range represents results from the nine combinations of air exchange rate and rom height (see Sections 4.7.3
and 7.5, below).
Final, February 2005
7-7
ISCORS Technical Report 2004-03
-------
-------
8 CONCLUSIONS
This report describes computations undertaken to assess the potential radiation exposures
associated with the handling, beneficial use, and disposal of sewage sludge that contains certain
naturally-occurring and/or man-made radioactive materials. The primary objective of this Dose
Modeling exercise is to provide perspective on the levels of radionuclides detected in the
ISCORS POTW Survey, taking into account typical sludge management practices.
The computations have been undertaken using probabilistic versions of three members of a
widely employed family of environmental transport codes: RESRAD, RESRAD-OFFSITE, and
RESRAD BUILD. The principal outputs are the tables of Dose-to-Source Ratios (DSR) for the
relevant radionuclides, under seven hypothetical sludge management scenarios, and the
associated tables of multiplicative factors that correct for multiple years of sludge application.
The 95th-percentile DSR value, for a particular radionuclide and scenario, relates the
95th-percentile level of dose, as determined in a Monte Carlo computation, to an average member
of the critical population group that would result from the presence of unit activity concentration
in sludge—that is, for 37 Bq per kilogram (1 pCi per gram) of dry sludge.
As expected, the DSR values range widely within each scenario, for the various radionuclides,
and there is significant variance among the scenarios. These differences, however, are
meaningful only when considered in the context of the concentrations in sludge actually found in
the POTW Survey. Chapter 7 of this report combines the DSRs computed here with the Survey
measurements, and makes it clear that while some scenarios and radionuclides give rise to very
low doses, there are other radionuclide-scenario combinations that may be of concern. In
particular, the calculated 95th-percentile sample dose for the Onsite Resident (with 50 years or
100 years of prior sludge application), and that for POTW Workers involved in sludge loading,
exceed 1 mSv/yr (100 mrem/yr)14. Doses to the POTW incinerator neighbor (after 50 years of
incineration) and the sludge application worker (after 50 years of field application), on the other
hand, were below 0.1 mSv/yr (10 mrem/year), and those to the recreational user, residents of a
nearby town, and neighbors of a landfill were all of little consequence.
The basic conclusions of this report are as follows:
•• None of the non-POTW scenarios show a significant current widespread threat to public
health. For instance, the scenarios with the largest potential critical groups—the Nearby
Town and the Incinerator—show relatively small estimated doses.
•• If agricultural land application is carried out for a long time into the future, then the potential
exists for future radiation exposure primarily due to Radon. This is illustrated in the 50- and
100-year application subscenarios of the Onsite Resident.
•• In specific cases of very high levels of radioactive materials (e.g., levels above the 95%),
there is the potential for localized radiation exposure.
14 The current limit of total radiation exposure to the individual members of the general public from all controllable
sources, as recommended by the International Commission on Radiological Protection as well as the National
Council on Radiation Protection and Measurements, is 1 mSv/year (100 mrem/year).
Final, February 2005 8-1 ISCORS Technical Report 2004-03
-------
•• Within the POTW, little exposure is expected for sampling and transport. Only when workers
are in the same room with large quantities of sludge (e.g., for storage or loading) is there the
potential for significant exposure, predominantly due to Radon. In this case, the degree of
exposure is likely to depend highly on the configuration of the POTW in terms of room sizes,
ventilation, etc.
The doses computed for the On-Site Resident and the POTW Worker are notable; but several
important factors account for these elevated values, suggesting that typical exposures would not
necessarily approach such levels:
•• The exposure scenarios are somewhat conservative; in addition, the doses mentioned above
are upper-end percentile values.
•• The doses for the Onsite Resident for 50 years or 100 years of annual application would be
significant—but very few farms in the country, so far, have used sewage sludge for even
20 years.
•• High doses are generally attributable to the indoor radon pathway. For the Onsite Resident,
the 95-percentile sample doses tend to be a factor of 6.5 higher than the corresponding median
(50-percentile) sample doses, regardless of the number of years of application, simply because
of the difference in the concentration of radium in the sludge (13 pCi/gm versus 2 pCi/gm).
Both for the Onsite Resident and the POTW Worker, exposures can be decreased radically
through the use of readily available radon testing and mitigation technologies.
The Subcommittee has determined that the results of this analysis, based on actual sludge and
ash samples and the RESRAD model, are of acceptable quality for the stated purposes of this
project. While it would always be advantageous to look at other scenarios, if resources allowed,
the seven that have been developed for this analysis represent the range of current practices for
managing sewage sludge and ash, and the major possible routes of exposure to them.
The RESRAD family of codes has been employed in a variety of regulatory analyses of
environmental radiation exposures, and is continually being developed and improved to enhance
its applicability to a broader range of situations. Although it is widely accepted, and has been
field tested and validated for many applications, validation of the results of this analysis would
enhance their value to a decision-maker. If the approach described in this report is employed in
the analysis of a specific site, one or more of the scenarios developed herein may provide useful
guides. However, some site-specific conditions are likely to differ substantially from those
assumed for these scenarios, and may require using different parameter values and distributions.
ISCORS Technical Report 2004-03 8-2 Final, February 2005
-------
9 REFERENCES
EPA "Land Application of Municipal Sludge; Process Design Manual," EPA/625-1-83-016.
U.S. Environmental Protection Agency: Washington, DC. 1983.
EPA "Limiting Values of Radionuclide Intake and Air Concentration and Dose Conversion
Factors for Inhalation, Submersion, and Ingestion, Federal Guidance Report No. 11,"
EPA/520-1-88-020. U.S. Environmental Protection Agency: Washington, DC. 1988a.
EPA "Report to Congress: Solid Waste Disposal in the United States,"
EPA/530-SW-88-011A. U.S. Environmental Protection Agency: Washington, DC.
1988b.
EPA "Technical Support Document for Sewage Sludge Incineration," U.S. Environmental
Protection Agency Office of Water, Washington, DC. 1992a.
EPA "User's Guide for CAP88-PC Version 1.0," EPA/402-B-92-001. U.S. Environmental
Protection Agency: Washington, DC. 1992b.
EPA "External Exposure to Radionuclides in Air, Water, and Soil, Federal Guidance Report
No. 12," EPA/402-R-93-081. U.S. Environmental Protection Agency, Washington, DC.
1993a.
EPA "Wildlife Exposure Factors Handbook," EPA/600/R-93/187. U.S. Environmental
Protection Agency: Washington, DC. 1993b.
EPA. "Land Application of Sewage Sludge and Domestic Septage; Process Design Manual,"
EPA/625-R-95-001. U.S. Environmental Protection Agency: Washington, DC. 1995.
EPA "Exposure Factors Handbook," EPA/600-P-95-002Fa. U.S. Environmental Protection
Agency, Washington, DC. 1997.
EPA Code of Federal Regulations, 40 CFR 258, U.S. Environmental Protection Agency,
Washington, DC.
EPA Code of Federal Regulations, 40 CFR 503, U.S. Environmental Protection Agency,
Washington, DC.
EPA "Joint NRC/EPA Sewage Sludge Radiological Survey: Survey Design and Test Site
Results," EPA 832-R-99-900. U.S. Environmental Protection Agency: Washington, DC.
1999a.
EPA "Cancer Risk Coefficients for Environmental Exposure to Radionuclides, Federal
Guidance Report No. 13," EPA 402-R-99-001. U.S. Environmental Protection Agency,
Washington, DC. 1999b.
Final, February 2005 9-1 ISCORS Technical Report 2004-03
-------
Fulbright, T.E. "Food plots for white-tailed deer." Wildlife Management Bulletin No. 3, Caesar
Kleberg Wildlife Research Institute, Texas A&M University-Kingsville. 1999.
GAO "Nuclear Regulation: Action Needed to Control Radioactive Contamination at Sewage
Treatment Plants," GAO/RCED-94-133. U.S. Government Accounting Office:
Washington, DC. 1994.
ICRP "Recommendations of the International Commission on Radiological Protection,"
ICRP Publication 26. Pergamon Press: Oxford. 1977.
ICRP "Limits for the Intake of Radionuclides by Workers, Part 1," ICRP Publication 30.
Pergamon Press: Oxford. 1979.
Metro. "Metrogro Farm Update," Issue 11, Denver Metro Wastewater Reclamation District,
Summer/Fall, 2000.
NCRP "Radiological Assessment," Publication 76. National Council on Radiation Protection
and Measurements (NCRP): Bethesda, MD. 1984.
NCRP "Recommended Screening Limits for Contaminated Surface Soil and Review of Factors
Relevant to Site-Specific Studies," Publication 129. National Council on Radiation
Protection and Measurements (NCRP): Bethesda, MD. 1999.
Nebraska Game and Parks Commission, "The White Tail Deer," Lincoln, NE, 2001, available at
.
NRC Till, I.E. and H.R. Myer. "Radiological Assessment: A Textbook on Environmental
Dose Analysis," NUREG/CR-3332. Office of Nuclear Reactor Regulation, U.S. Nuclear
Regulatory Commission: Washington, DC. September 1983.
NRC Kozak, M.W., C.P. Harlan, M.S.Y. Chu, B.L. O'Neal, C.D. Updegraff, and
P.A. Mattingly. "Background Information for the Development of a Low-Level Waste
Performance Assessment Methodology: Identification of Potential Exposure Pathways,"
NUREG/CR-5453, Volume 3. U.S. Nuclear Regulatory Commission: Washington, DC.
December 1989.
NRC Kozak, M.W., C.P. Harlan, M.S.Y. Chu, B.L. O'Neal, C.D. Updegraff, and
P.A. Mattingly. "Background Information for the Development of a Low-Level Waste
Performance Assessment Methodology: Selection and Integration of Models,"
NUREG/CR-5453, SAND89-2509, Volume 4. U.S. Nuclear Regulatory Commission:
Washington, DC. December 1989.
NRC 10 CFR 20.2003. U.S. Nuclear Regulatory Commission: Washington, DC.
ISCORS Technical Report 2004-03 9-2 Final, February 2005
-------
NRC Kennedy, W.E., M.A. Parkhurst, R.L. Aaberg, K.C. Rhoads, R.L. Hill, and J.B. Martin,
"Evaluation of Exposure Pathways to Man from Disposal of Radioactive Materials into
Sanitary Sewer Systems," NUREG/CR-5814. U.S. Nuclear Regulatory Commission:
Washington, DC. 1992a.
NRC Kennedy, W.E. and D.L. Strenge. "Residual Radioactive Contamination from
Decommissioning," NUREG/CR-5512, Volume 1. U.S. Nuclear Regulatory
Commission: Washington, DC. 1992b.
NRC Kamboj, S., C. Yu, B.M. Biwer, and T. Klett. "Probabilistic Dose Analysis Using
Parameter Distributions Developed for RESRAD and RESRAD-BUILD Codes,"
NUREG/CR-6676, ANL/EAD/TM-89. U.S. Nuclear Regulatory Commission:
Washington, DC. 2000a.
NRC Yu, C., D. LePoire, E. Gnanapragasam, J. Arnish, S. Kamboj, B.M. Biwer, Cheng, J.-J.,
A. Zielen, and S.Y. Chen. "Development of Probabilistic RESRAD 6.0 and
RESRAD-BUILD 3.0 Computer Codes," NUREG/CR-6697, ANL/EAD/TM-98.
U.S. Nuclear Regulatory Commission: Washington, DC. 2000b.
OSHA Code of Federal Regulations. 29 CFR 1910, SubpartZ. Occupational Safety and Health
Administration: Washington, DC.
Sopper, W.E. "Municipal Sludge Use in Land Reclamation." Lewis Publishers. 1993.
Schroeder, P.R., T.S. Dozier, P.A. Zappi, B.M. McEnroe, J.W. Sjostrom, and R.L. Peyton.
(1994). "The Hydrologic Evaluation of Landfill Performance (HELP) Model: Engineering
Documentation for Version 3," EPA/600/R-94/168b. Office of Research and Development,
U.S. Environmental Protection Agency: Washington, DC. September 1994.
Washington State Department of Health. Brennan, M.J., "The Presence of Radionuclides in
Sewage Sludge and their Effect on Human Health", WDOH/320-013, Washington State
Department of Health, Division of Radiation Protection, Olympia, WA, 1997.
Yu, C., A. Zielen, J.-J. Cheng, D. LePoire, E. Gnanapragasam, S. Kamboj, J. Arnish, and
A. Wallo, III; W.A. Williams; and H. Peterson. "Users's Manual for RESRAD Version 6"
2001.
Final, February 2005 9-3 ISCORS Technical Report 2004-03
-------
-------
Appendix A
Baseline Parameter Values and
Distributions
-------
-------
A.1 Introduction
This appendix contains the "baseline" parameter values and distributions used in the RESRAD
calculations. The tables are divided into two sections. The first section is baseline values and
distributions that are used by multiple RESRAD codes, such as partition coefficients (Kd). The
second section contains the values and distributions for the RESRAD codes RESRAD 6.0,
RESRAD OFFSITE, and RESRAD-BUILD 3.0.
In performing the deterministic computations, it is necessary to replace distributions with a
single value. This assessment chose to use a central tendency of the distribution. In particular
the geometric mean is employed for parameters with a lognormal or log-uniform distribution,
and the arithmetic mean for all others1. Mean values were determined with the Mathematica
software, and are listed in the tables along with the distributions themselves. While it is
recognized that no measure of central tendency is ideal, there are several reasons for adopting the
distribution mean. Our stated objective is to model the "average member" of the critical group;
using the median would imply a 50 percentile member of the group, not the average member.
Also, it was found that the mean led to doses that were near to the mean of the probabilistic
doses, where the two could be compared. It should be borne in mind, in any case, that
deterministic calculations are used only for sensitivity analyses and for scaling the effects of
multiple years of application, and not in the computation of absolute values of the sludge dose-
to-source ratios.
A.2 Parameters Used in Multiple Codes
Note: The parameters m and s for the log-normal distribution are defined as follows. If x is
log-normally distributed, then this means that the natural logarithm of x, ln(x), has a normal
distribution with mean of ln(x) = m, and the standard deviation of ln(x) = s.
1 In most cases, the scaling factors for multi-year applications were virtually the same whether parameter
distributions were replaced with their means or their medians. In the few cases where there was a significant
difference, the use of mean parameters gave a larger scaling factor, which would lead to more conservative
results.
Final, February 2005 A-l ISCORS Technical Report 2004-03
-------
Table A.1 Baseline Values and Distributions for the Kd Parameter
Element of
Interest
Ac
Am
Ba
Be
Bi
C
Ce
Co
Cr
Cs
Eu
Fe
H
I
In
K
La
Np
Pa
Pb
Po
Pu
Ra
Sm
Sr
Th
Tl
U
Zn
RESRAD 6.0
Default
Value
20
20
50
929
0
0
1000
1000
103
1000
825*
1000
0
0.1
158
5.5
4.98
257*
50
100
10
2000
70
825*
30
60,000
0
50
0
Baseline
Value as
Geometric
Mean of the
Distribution
825
1445
560
929
105
11
1998
235
103
446
825
209
0.06
4.6
158
5.5
4.98
17
380
2392
181
953
3533
825
32
5884
71
126
1075
Distribution from NUREG/CR-6697
Truncated Lognormal-n Distribution Parameters**
•
6.72
7.28
6.33
6.84
4.65
2.40
7.6
5.46
4.63
6.10
6.72
5.34
-2.81
1.52
5.07
1.7
1.61
2.84
5.94
7.78
5.20
6.86
8.17
6.72
3.45
8.68
4.26
4.84
6.98
•
3.22
3.15
3.22
3.22
3.22
3.22
2.08
2.53
2.76
2.33
3.22
2.67
.5
2.19
3.22
0.49
3.22
2.25
3.22
2.76
1.68
1.89
1.70
3.22
2.12
3.62
3.22
3.13
4.44
exp(- )
825
1445
560
929
105
11
1998
235
103
446
825
209
.06
4.6
158
5.5
4.98
17
380
2392
181
953
3533
825
32
5884
71
126
1075
* Value calculated by RESRAD using a correlation with the plant transfer factor.
** Distribution is truncated at a lower quantile of 0.001 and an upper quantile of 0.999.
ISCORS Technical Report 2004-03
A-2
Final, February 2005
-------
Table A.2 Baseline Values and Distributions for the Plant Transfer Factor
Element of
Interest
Ac
Am
Ba
Be
Bi
C
Ce
Co
Cr
Cs
Eu
Fe
H
I
In
K
La
Np
Pa
Pb
Po
Pu
Ra
Sm
Sr
Th
Tl
U
Zn
RESRAD 6.0
Default Value
2.5 x 10'3
1.0 x lO'3
5.0 x IQ-3
4.0 x lO'3
1.0 x 1Q-1
5.5
2.0 x 10'3
8.0 x IQ-2
2.5 x 10'4
4.0 x 10'2
2.5 x IQ-3
1.0 x 10'3
4.8
2.0 x IQ-2
3.0 x 10'3
3.0 x 1Q-1
2.5 x 10'3
2.0 x 10'2
1.0 x IQ-2
1.0 x 10'2
1.0 x IQ-3
1.0 x IQ-3
4.0 x 10'2
2.5 x IQ-3
3.0 x 10'1
1.0 x 10'3
2.0 x lO'1
2.5 x 10'3
4.0 x 1Q-1
Baseline
Value as
Geometric
Mean of the
Distribution
1.0 x IQ-3
1.0 x IQ-3
1.0 x 10'2
4.0 x IQ-3
1.0 x 10'1
7.0 x 10'1
2.0 x IQ-3
8.0 x 10'2
1.0 x IQ-2
4.0 x IQ-2
2.0 x 10'3
1.0 x IQ-3
4.8
2.0 x 10'2
3.0 x IQ-3
3.0 x 10'1
2.0 x IQ-3
2.0 x IQ-2
1.0 x 10'2
4.0 x IQ-3
1.0 x 10'3
1.0 x 10'3
4.0 x IQ-2
2.0 x 10'3
3.0 x 1Q-1
1.0 x IQ-3
2.0 x 10'1
2.0 x IQ-3
4.0 x 10'1
Distribution from NUREG/CR-6697
Truncated Lognormal-n Distribution Parameters*
•
-6.91
-6.91
-4.61
-5.52
-2.30
-0.36
-6.21
-2.53
-4.61
-3.22
-6.21
-6.91
1.57
-3.91
-5.81
-1.20
-6.21
-3.91
-4.61
-5.52
-6.9
-6.91
-3.22
-6.21
-1.20
-6.91
-1.61
-6.21
-0.92
•
1.1
0.9
1.1
1.1
1.1
0.9
1.0
0.9
1.0
1.0
1.1
0.9
1.1
0.9
1.1
1.1
0.9
0.9
1.1
0.9
0.9
0.9
0.9
1.1
1.0
0.9
1.1
0.9
0.9
exp(- )
1.0 x 10'3
1.0 x 10'3
1.0 x IQ-2
4.0 x 10'3
1.0 x 1Q-1
7.0 x lO'1
2.0 x 10'3
8.0 x IQ-2
1.0 x 10'2
4.0 x 10'2
2.0 x IQ-3
1.0 x 10'3
4.8
2.0 x IQ-2
3.0 x 10'3
3.0 x 1Q-1
2.0 x 10'3
2.0 x 10'2
1.0 x IQ-2
4.0 x 10'3
1.0 x IQ-3
1.0 x IQ-3
4.0 x 10'2
2.0 x IQ-3
3.0 x 10'1
1.0 x 10'3
2.0 x lO'1
2.0 x 10'3
4.0 x 1Q-1
* Distribution is truncated at a lower quantile of 0.001 and an upper quantile of 0.999.
Final, February 2005
A-3
ISCORS Technical Report 2004-03
-------
Table A.3 Baseline Values and Distribution for the Meat Transfer Factor
Element of
Interest
Ac
Am
Ba
Be
Bi
C
Ce
Co
Cr
Cs
Eu
Fe
H
I
In
K
La
Np
Pa
Pb
Po
Pu
Ra
Sm
Sr
Th
Tl
U
Zn
RESRAD 6.0
Default Value
2.0 x lO'5
5.0 x IQ-5
2.0 x IQ-4
1.0 x IQ-3
2.0 x 10'3
3.1 x 10'2
2.0 x 10'5
2.0 x 10'2
9.0 x IQ-3
3.0 x IQ-2
2.0 x IQ-3
2.0 x IQ-2
1.2 x 10'2
7.0 x 10'3
4.0 x 10'3
2.0 x 10'2
2.0 x IQ-3
1.0 x IQ-3
5.0 x IQ-3
8.0 x IQ-4
5.0 x 10'3
1.0 x 10'4
1.0 x 10'3
2.0 x 10'3
8.0 x IQ-3
1.0 x IQ-4
2.0 x IQ-2
3.4 x IQ-4
1.0 x 10'1
Baseline
Value as
Geometric
Mean of the
Distribution
2.0 x 10'5
5.0 x 10'5
2.0 x 10'4
5.0 x 10'3
2.0 x IQ-3
3.0 x IQ-2
2.0 x IQ-5
3.0 x IQ-2
3.0 x IQ-2
5.0 x 10'2
2.0 x 10'3
3.0 x 10'2
1.2 x IQ-2
4.0 x 10'2
4.0 x 10'3
2.0 x IQ-2
2.0 x 10'3
1.0 x 10'3
5.0 x 10'6
8.0 x 10'4
5.0 x IQ-3
1.0 x IQ-4
1.0 x IQ-3
2.0 x IQ-3
1.0 x 10'2
1.0 x 10'4
2.0 x 10'2
8.0 x 10'4
1.0 x 1Q-1
Distribution from NUREG/CR-6697
Truncated Lognormal-n Distribution Parameters*
•
-10.82
-9.90
-8.52
-5.30
-6.21
-3.47
-10.82
-3.51
-3.51
-3.00
-6.21
-3.51
-4.42
-3.22
-5.52
-3.91
-6.21
-6.91
-12.21
-7.13
-5.30
-9.21
-6.91
-6.21
-4.61
-9.21
-3.91
-7.13
-2.30
•
1.0
0.2
0.9
1.0
1.0
1.0
0.9
1.0
0.4
0.4
1.0
0.4
1.0
0.4
1.0
0.2
1.0
0.7
1.0
0.7
0.7
0.2
0.7
1.0
0.4
1.0
1.0
0.7
0.3
exp(- )
2.0 x 10'5
5.0 x 10'5
2.0 x 10'4
5.0 x 10'3
2.0 x IQ-3
3.0 x IQ-2
2.0 x IQ-5
3.0 x IQ-2
3.0 x 10'2
5.0 x 10'2
2.0 x 10'3
3.0 x 10'2
1.2 x IQ-2
4.0 x IQ-2
4.0 x IQ-3
2.0 x IQ-2
2.0 x 10'3
1.0 x 10'3
5.0 x 10'6
8.0 x 10'4
5.0 x IQ-3
1.0 x IQ-4
1.0 x IQ-3
2.0 x IQ-3
1.0 x 10'2
1.0 x 10'4
2.0 x 10'2
8.0 x 10'4
1.0 x 1Q-1
* Distribution is truncated at a lower quantile of 0.001 and an upper quantile of 0.999.
ISCORS Technical Report 2004-03
A-4
Final, February 2005
-------
Table A.4 Baseline Values and Distributions for the Milk Transfer Factor
Element of
Interest
Ac
Am
Ba
Be
Bi
C
Ce
Co
Cr
Cs
Eu
Fe
H
I
In
K
La
Np
Pa
Pb
Po
Pu
Ra
Sm
Sr
Th
Tl
U
Zn
RESRAD 6.0
Default Value
2.0 x ID'5
2.0 x IQ-6
5.0 x 10'4
2.0 x lO'6
5.0 x 10'4
1.2 x 10'2
3.0 x IQ-5
2.0 x 10-3
2.0 x 1C'3
8.0 x 1C'3
2.0 x lO'5
3.0 x 10'4
1.0 x 10'2
1.0 x 10'2
2.0 x IQ-4
7.0 x IQ-3
2.0 x IQ-5
5.0 x IQ-6
5.0 x lO'6
3.0 x lO'4
3.4 x 10'4
1.0 x 10'6
1.0 x IQ-3
2.0 x IQ-5
2.0 x 1C'3
5.0 x IQ-6
3.0 x lO'3
6.0 x 10'4
1.0 x 10'2
Baseline
Value as
Geometric
Mean of the
Distribution
2.0 x 10'6
2.0 x 10'6
5.0 x IQ-4
2.0 x IQ-6
1.0 x IQ-3
1.2 x IQ-2
3.0 x 10'5
2.0 x 10'3
2.0 x 10'3
1.0 x 10'2
6.0 x IQ-5
3.0 x IQ-4
1.0 x IQ-2
1.0 x IQ-2
2.0 x 10'4
7.0 x 10'3
6.0 x 10'5
1.0 x 10'5
5.0 x IQ-6
3.0 x IQ-4
4.0 x IQ-4
1.0 x IQ-6
1.0 x 10'3
6.0 x 10'5
2.0 x 10'3
5.0 x 10'6
3.0 x IQ-3
4.0 x IQ-4
1.0 x IQ-2
Distribution from NUREG/CR-6697
Truncated Lognormal-n Distribution Parameters*
•
-13.12
-13.12
-7.60
-13.12
-6.91
-4.4
-10.41
-6.21
-6.21
-4.61
-9.72
-8.11
-4.6
-4.61
-8.52
-4.96
-9.72
-11.51
-12.21
-8.11
-7.82
-13.82
-6.91
-9.72
-6.21
-12.21
-5.81
-7.82
-4.61
•
0.9
0.7
0.7
0.9
0.9
0.9
0.7
0.7
0.7
0.5
0.9
0.7
0.9
0.5
0.9
0.5
0.9
0.7
0.9
0.9
0.7
0.5
0.5
0.9
0.5
0.9
0.9
0.6
0.9
exp(- )
2.0 x IQ-6
2.0 x IQ-6
5.0 x IQ-4
2.0 x IQ-6
1.0 x 1Q-3
1.2 x 1Q-2
3.0 x IQ-5
2.0 x IQ-3
2.0 x IQ-3
1.0 x IQ-2
6.0 x IQ-5
3.0 x IQ-4
1.0 x 1Q-2
1.0 x 1Q-2
2.0 x IQ-4
7.0 x IQ-3
6.0 x IQ-5
1.0 x IQ-5
5.0 x IQ-6
3.0 x IQ-4
4.0 x 1Q-4
1.0 x 1Q-6
1.0 x IQ-3
6.0 x IQ-5
2.0 x IQ-3
5.0 x IQ-6
3.0 x IQ-3
4.0 x IQ-4
1.0 x 1Q-2
* Distribution is truncated at a lower quantile of 0.001 and an upper quantile of 0.999.
Final, February 2005
A-5
ISCORS Technical Report 2004-03
-------
Table A.5 Baseline Values and Distributions for the Aquatic Food (Fish)
Transfer Factor
Element of
Interest
Ac
Am
Ba
Be
Bi
C
Ce
Co
Cr
Cs
Eu
Fe
H
I
In
K
La
Np
Pa
Pb
Po
Pu
Ra
Sm
Sr
Th
Tl
U
Zn
RESRAD 6.0
Default Value
15
30
4.0
100
15
50000
30
300
200
2000
50
200
1
40
10000
1000
30
30
10
300
100
30
50
25
60
100
10,000
10
1000
Baseline
Value as
Geometric
Mean of the
Distribution
15
30
4.0
100
15
49000
30
300
200
2000
50
200
1
40
10000
1000
30
30
10
300
100
30
50
25
60
100
10,000
10
1000
Disbribution from NUREG/CR-6697
Lognormal Distribution Parameters
•
2.7
3.4
1.4
4.6
2.7
10.8
3.4
5.7
5.3
7.6
3.9
5.3
0
3.7
9.2
6.9
3.4
3.4
2.3
5.7
4.6
3.4
3.9
3.2
4.1
4.6
9.2
2.3
6.9
•
1.1
1.1
1.1
1.1
1.1
1.1
1.1
1.1
1.1
0.7
1.1
1.1
0.1
1.1
1.1
1.1
1.1
1.1
1.1
1.1
1.1
1.1
1.1
1.1
1.1
1.1
1.1
1.1
1.1
exp(- )
15
30
4.0
100
15
49000
30
300
200
2000
50
200
1
40
10000
1000
30
30
10
300
100
30
50
25
60
100
10,000
10
1000
ISCORS Technical Report 2004-03
A-6
Final, February 2005
-------
A.3 Code-Specific Parameters
Table A.6 Probability Distribution Notations Used in Baseline Parameter Tables
Notation
TruncN(* • • • a, b)
TruncLogN(* • • • a, b)
BoundedLogN(* • • • a, b)
Uniform(a, b)
LogU(a, b)
Triangular(a, c, b)
Continuous Linear
Continuous Log
Type of Distribution
Truncated Normal
Truncated Lognormal
Bounded Lognormal
Uniform
Loguniform
Triangular
Empirical
Empirical
The following notation is used in the baseline tables:
* Mean value of the distribution.
* * Geometric mean value of the distribution.
* * * Not an input parameter in RESRAD .
( ) RESRAD or RESRAD -Off site default value not used as baseline value.
N/A Not applicable.
Final, February 2005
A-7
ISCORS Technical Report 2004-03
-------
Gfl
O
Table A.7 RESRAD Baseline Parameter Values and Distributions
Input Parameters
RESRAD Default
Values
Baseline Values
(if other than
the default)
NUREG/CR-6697
Probabilistic
Distributions / Baseline
Distributions (if other
than
NUREG/CR-6697)
Comments for Baseline
Values/Distributions
Title
Title
Dose Factor Library
Cut-off Half Life (180 d or 30 d)
Default File
(180 d)
Scenario
dependent
30 d
Scenario Definition
RESRAD Default Library
Graphics Parameters
Number of Points (32, 64, 128, 256,
512, 1024)
Linear Spacing/Log Spacing
32
Log Spacing
Time Integration Parameters
Maximum No of Points for Dose
Maximum No of Points for Risk
17
(257)
1
Radiation dose instead of cancer risk is
concerned in the analyses. Using a smaller
integration point will shorten the calculation
time.
User Preferences
Use Line Draw Character (yes/no)
Find Peak Pathway Dose (yes/no)
yes
yes
in
ft
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21
8
Table A.7 RESRAD Baseline Parameter Values and Distributions (continued)
Input Parameters
Save All Files After Each Run
(yes/no)
Time Integrated Probabilistic Risk
(yes/no)
RESRAD Default
Values
no
no
Baseline Values
(if other than
the default)
yes
NUREG/CR-6697
Probabilistic
Distributions / Baseline
Distributions (if other
than
NUREG/CR-6697)
Comments for Baseline
Values/Distributions
Calculation Times
Basic Radiation Dose Limit
(mrem/year)
Times for Calculation (years)
25
(1000)
1023
Values used to obtain dose results for each
year.
Source
Nuclide Concentration (pCi/g)
(100)
0.0044
Scenario definition. Corresponds to a soil
density of 1.52 g/cm3.
Contaminated Zone Parameters
Area of Contaminated Zone (m2)
Thickness of Contaminated Zone (m)
Length Parallel to Aquifer Flow (m)
(10000)
(2)
(100)
404685
0.15
636
Scenario definition (lacre = 4046 square
meter).
Scenario definition (15 cm depth of
contamination)
Scenario definition (square root of the area).
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Gfl
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Table A.7 RESRAD Baseline Parameter Values and Distributions (continued)
Input Parameters
RESRAD Default
Values
Baseline Values
(if other than
the default)
NUREG/CR-6697
Probabilistic
Distributions / Baseline
Distributions (if other
than
NUREG/CR-6697)
Comments for Baseline
Values/Distributions
Cover & Contaminated Zone Hydrological Data
Cover Depth (m)
Density of Cover Material (g/cm3)
Cover Erosion Rate (m/yr)
Density of Contaminated Zone
(g/cm3)
Contaminated Zone Erosion Rate
(m/yr)
Contaminated Zone Total Porosity
Contaminated Zone Field Capacity
Contaminated Zone Hydraulic
Conductivity (m/yr)
Contaminated Zone b Parameter
Humidity in Air (g/m3)
Evapotranspiration Coefficient
0
1.5
0.001
(1.5)
(0.001)
(0.4)
0.2
(10)
(5.3)
(8)
(0.5)
1.52*
0
0.426
9.974**
2.895**
7.243**
0.625*
BoundedLogN(2.3, 2.11,
0.004, 9250)
BoundedLogN(1.06,
0.66, 0.5, 30)
TruncLogN(1.98, 0.334,
0.001, 0.999)
Uniform(0.5, 0.75)
Scenario Definition (No cover layer
assumed)
Not required when cover depth equals zero.
Not required when cover depth equals zero.
0 was used in dose analysis to get
conservative results.
Values was calculated using density of the
contaminated zone.
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21
8
Table A.7 RESRAD Baseline Parameter Values and Distributions (continued)
Input Parameters
Wind Speed (m/s)
Precipitation (m/yr)
Irrigation (m/yr)
Irrigation mode (Overhead/Ditch)
Runoff Coefficient
Watershed Area for Nearby Stream or
Pond (m2)
Accuracy for Water/Soil Computation
RESRAD Default
Values
(2)
1.0
0.2
Overhead
(0.2)
1000000
0.001
Baseline Values
(if other than
the default)
4.242**
0.45*
NUREG/CR-6697
Probabilistic
Distributions / Baseline
Distributions (if other
than
NUREG/CR-6697)
BoundedLogN(1.445,
0.2419, 1.4, 13)
Uniform(0. 1,0.8)
Comments for Baseline
Values/Distributions
Saturated Zone Hydrological Data
Density (g/cm3)
Effective Porosity
Total Porosity
Field Capacity
Hydraulic Conductivity (m/yr)
(1.5)
(0.2)
(0.4)
0.2
(100)
1.52*
0.355*
0.425*
9.974**
TruncN(1.52, 0.230,
0.001, 0.999)
TruncN(0.355, 0.0906,
0.001, 0.999)
TruncN(0.425, 0.0867,
0.001, 0.999)
BoundedLogN(2.3,2.11,
0.004, 9250)
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6
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Gfl
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Table A.7 RESRAD Baseline Parameter Values and Distributions (continued)
Input Parameters
b Parameter
Hydraulic Gradient
Water Table Drop Rate (m/yr)
Well Pump Intake Depth (m below
water table)
Model for Water Transportation
(Nondispersion/Mass-Balance)
Well Pumping Rate (mVyr)
RESRAD Default
Values
(5.3)
(0.02)
(0.001)
(10)
Nondispersion
250
Baseline Values
(if other than
the default)
0.00604**
0
15.33*
NUREG/CR-6697
Probabilistic
Distributions / Baseline
Distributions (if other
than
NUREG/CR-6697)
BoundedLogN(-5.11,
1.77, 7e-5, 0.5)
Triangular(6, 10, 30)
Comments for Baseline
Values/Distributions
Not required when the water table drop rate
was set to 0.
0 was used to get conservative dose results.
Unsaturated Zone Parameters
Thickness (m)
Density (g/cm3)
Effective Porosity
Total Porosity
Field Capacity
(4)
(1.5)
(0.2)
(0.4)
0.2
9.895**
1.52*
0.355*
0.425*
BoundedLogN(2.2926,
1.276,0.18,320)
TruncN(1.52, 0.230,
0.001, 0.999)
TruncN(0.355, 0.0906,
0.001, 0.999)
TruncN(0.425, 0.0867,
0.001, 0.999)
"8
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21
8
Table A.7 RESRAD Baseline Parameter Values and Distributions (continued)
Input Parameters
Hydraulic Conductivity (m/yr)
b Parameter
RESRAD Default
Values
(10)
(5.3)
Baseline Values
(if other than
the default)
9.974**
2.895**
NUREG/CR-6697
Probabilistic
Distributions / Baseline
Distributions (if other
than
NUREG/CR-6697)
BoundedLogN(2.3,2.11,
0.004, 9250)
BoundedLogN(1.06,
0.66, 0.5, 30)
Comments for Baseline
Values/Distributions
Occupancy, Inhalation and External Gamma Data
Inhalation Rate (nrVyr)
Mass Loading for Inhalation (g/m3)
Exposure Duration (y)
Indoor Dust Filtration Factor
External Gamma Shielding Factor
Indoor Time Fraction
Outdoor Time Fraction
Shape of Contaminated Zone
(circular/noncircular)
(8400)
(0.001)
30
(0.4)
(0.7)
(0.5)
0.25
circular
8627*
2.45E-05*
0.55*
0.27**
0.651*
Triangular(4380, 8400,
13100)
Continuous Linear
Uniform(0.15, 0.95)
BoundedLogN(-1.3,
0.59, 0.044, 1)
Ingestion Pathway Dietary Data
Fruit, Vegetable and Grain
Consumption (kg/yr)
(160)
210.33*
Triangular(135, 178,
318)
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6
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Table A.7 RESRAD Baseline Parameter Values and Distributions (continued)
Input Parameters
Leafy Vegetable Consumption (kg/yr)
Milk (L/yr)
Meat and Poultry (kg/yr)
Fish (kg/yr)
Other Sea Food (kg/yr)
Soil Ingestion (g/yr)
Drinking Water Intake (L/yr)
RESRAD Default
Values
(14)
(92)
(63)
(5.4)
(0.9)
(36.5)
(510)
Baseline Values
(if other than
the default)
22.667*
120.67*
222.1*
155.6*
0
18.27*
409.5**
NUREG/CR-6697
Probabilistic
Distributions / Baseline
Distributions (if other
than
NUREG/CR-6697)
No distribution /
Triangular (13, 25, 30)
Triangular (60, 102,
200)
No distribution /
Triangular (5.0, 72.6,
588.7)
No distribution /
Triangular (2.0, 56.3,
408.5)
Triangular (0, 18.3,
36.5)
TruncLogN(6.015,
0.489, 0.001, 0.999)
Comments for Baseline
Values/Distributions
Baseline distribution derived from EPA 1997
using methodology of NUREG/CR-6697.
Baseline distribution derived from EPA 1997
using methodology of NUREG/CR-6697.
Baseline distribution derived from EPA 1997
using methodology of NUREG/CR-6697.
No ocean fish.
Contaminated Fractions
Drinking Water
Household Water
Livestock water
Irrigation water
(1)
1
1
1
0.9
Scenario definition.
ft
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21
8
Table A.7 RESRAD Baseline Parameter Values and Distributions (continued)
Input Parameters
Aquatic food
Plant food
Meat
Milk
RESRAD Default
Values
(0.5)
-1
-1
-1
Baseline Values
(if other than
the default)
0.463*
NUREG/CR-6697
Probabilistic
Distributions / Baseline
Distributions (if other
than
NUREG/CR-6697)
Triangular(0, 0.39, 1)
Comments for Baseline
Values/Distributions
Calculated by RESRAD from area factor
Calculated by RESRAD from area factor
Calculated by RESRAD from area factor
Ingestion Pathway, Non-dietary Data
Livestock fodder intake for meat
(kg/d)
Livestock fodder intake for milk
(kg/d)
Livestock water intake for meat (L/d)
Livestock water intake for milk (L/d)
Livestock intake of soil (kg/d)
Mass loading for foliar deposition
(g/m3)
Depth of soil mixing layer (m)
Depth of roots (m)
68
55
50
160
0.5
0.0001
(0.15)
(0.9)
0.25*
2.15*
Triangular(0.0, 0.15,
0.6)
Uniform(0.3, 4.0)
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6
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-------
Gfl
O
Table A.7 RESRAD Baseline Parameter Values and Distributions (continued)
Input Parameters
RESRAD Default
Values
Baseline Values
(if other than
the default)
NUREG/CR-6697
Probabilistic
Distributions / Baseline
Distributions (if other
than
NUREG/CR-6697)
Comments for Baseline
Values/Distributions
Groundwater Fractional Usage
Drinking Water
Household Water
Livestock water
Irrigation water
1
1
(1)
(1)
0.5
0.5
To consider potential surface water
contamination as well.
To consider potential surface water
contamination as well.
Non-leafy Plant Factors
Wet Weight Crop Yield (kg/m2)
Length of Growing Season (y)
Translocation Factor
Weathering Removal Constant (1/yr)
Wet Foliar Interception Fraction
Dry Foliar Interception Fraction
(0.7)
0.17
0.1
(20)
0.25
0.25
1.75**
35.70*
TruncLogN(0.56, 0.48,
0.001, 0.999)
Triangular(5.1, 18,84)
Leafy Plant Factors
Wet Weight Crop Yield (kg/m2)
Length of Growing Season (y)
1.5
0.25
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21
8
Table A.7 RESRAD Baseline Parameter Values and Distributions (continued)
Input Parameters
Translocation Factor
Wet Foliar Interception Fraction
Dry Foliar Interception Fraction
RESRAD Default
Values
1
(0.25)
0.25
Baseline Values
(if other than
the default)
0.560*
NUREG/CR-6697
Probabilistic
Distributions / Baseline
Distributions (if other
than
NUREG/CR-6697)
Triangular(0.06, 0.67,
0.95)
Comments for Baseline
Values/Distributions
Fodder Plant Factors
Wet Weight Crop Yield (kg/m2)
Length of Growing Season (y)
Translocation Factor
Wet Foliar Interception Fraction
Dry Foliar Interception Fraction
1.1
0.08
1
0.25
0.25
Radon Data
Cover Total Porosity
Cover Volumetric Water Content
Cover Radon Diffusion Coefficient
(mVs)
Bldg Foundation Thickness (m)
Bldg Foundation Density (g/cm3)
0.4
0.05
2 x 10-6
0.15
2.4
N/A
N/A
N/A
No cover.
No cover.
No cover.
O
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Gfl
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Table A.7 RESRAD Baseline Parameter Values and Distributions (continued)
Input Parameters
Bldg Foundation Total Porosity
Bldg Foundation Volumetric Water
Content
Bldg Foundation Radon Diffusion
Coefficient (m2/s)
Contaminated Radon Diffusion
Coefficient (m2/s)
Radon Vertical Dimension of Mixing
(m)
Building Air Exchange Rate (1/hr)
Building Room Height (m)
Building Indoor Area Factor
Foundation Depth Below Ground
Surface (m)
Rn-222 Emanation Coefficient
Rn-220 Emanation Coefficient
RESRAD Default
Values
0.1
0.03
3 x 10'7
2 x 10'6
2
0.5
2.5
0
-1
0.25
0.15
Baseline Values
(if other than
the default)
NUREG/CR-6697
Probabilistic
Distributions / Baseline
Distributions (if other
than
NUREG/CR-6697)
Comments for Baseline
Values/Distributions
Value calculated by the code.
Value calculated by the code.
"8
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21
8
Table A.7 RESRAD Baseline Parameter Values and Distributions (continued)
Input Parameters
RESRAD Default
Values
Baseline Values
(if other than
the default)
NUREG/CR-6697
Probabilistic
Distributions / Baseline
Distributions (if other
than
NUREG/CR-6697)
Comments for Baseline
Values/Distributions
Storage Times Before Use Data
Fruits, Non-leafy Vegetables and
Grain (d)
Leafy Vegetables (d)
Milk (d)
Meat (d)
Fish (d)
Crustacea and Molusks (d)
Well Water (d)
Surface Water (d)
Livestock Fodder (d)
14
1
1
20
7
7
1
1
45
Carbon- 14 Data
C-12 Concentration in Local Water
C-12 Concentration in Contaminated
Soil
Fraction of Vegetation Carbon
Adsorbed from Soil
0.00002
0.03
0.02
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fa
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O
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Gfl
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Table A.7 RESRAD Baseline Parameter Values and Distributions (continued)
Input Parameters
Fraction of Vegetation Carbon
Adsorbed from Air
Thickness of Evasion Layer of C-14
in Soil
C-14 Evasion Flux Rate from Soil
C-12 Evasion Flux Rate from Soil
Grain Fraction in Livestock Feed
(Balance is Hay /Fodder) for Beef
Cattle
Grain Fraction in Livestock Feed
(Balance is Hay/Fodder) for Milk
Cow
DCF Correction Factor for Gaseous
Forms of C-14
RESRAD Default
Values
0.98
0.3
0.0000007
1E-10
0.8
0.2
88.94
Baseline Values
(if other than
the default)
0.367*
NUREG/CR-6697
Probabilistic
Distributions / Baseline
Distributions (if other
than
NUREG/CR-6697)
Triangular(0.2, 0.3, 0.6)
Comments for Baseline
Values/Distributions
ft
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Table A.8 RESRAD Baseline Parameter Correlations for Probabilistic Analyses
Parameter 1
Unsaturated Zone Soil Density
Saturated Zone Soil Density
Unsaturated Zone Total Porosity
Saturated Zone Total Porosity
Unsaturated Zone Soil Density
Saturated Zone Soil Density
Kd of U-238 in Contaminated Zone
Kd of U-238 in Unsaturated Zone
Kd of U-238 in Saturated Zone
Parameter 2
Unsaturated Zone Total Porosity
Saturated Zone Total Porosity
Unsaturated Zone Effective Porosity
Saturated Zone Effective Porosity
Unsaturated Zone Effective Porosity
Saturated Zone Effective Porosity
Kd of U-234 in Contaminated Zone
Kd of U-234 in Unsaturated Zone
Kd of U-234 in Saturated Zone
Correlation
Coefficient
-0.99
-0.99
0.96
0.96
-0.96
-0.96
0.99
0.99
0.99
Comments
The two parameters are strongly negatively
correlated.
The two parameters are strongly negatively
correlated.
A correlation of 0.96 provides satisfactory
pairing of sampling data.
A correlation of 0.96 provides satisfactory
pairing of sampling data.
The two parameters are strongly negatively
correlated.
The two parameters are strongly negatively
correlated.
To ensure the same Kd value was used by
different isotopes of the same element.
Same as above.
Same as above
O
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Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions
Input Parameters
New
Parameter
in
RESRAD-
Offsite ***
RESRAD-Offsite
Default Values
Baseline
Values (if
other than
the default)
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
Comments
Title
Title
Intermediate time points
Number of points (32, 64, 128,
256,512, 1024,2048,4096)
Linear spacing/Log Spacing
Minimum time increment
Dose factor library
Cut-off half life (180 days, 30 days, 6
hours)
Display update (0.25, 0.5, 1, 2, 4, 8,
16 sec)
Use line draw character
V
V
(128)
linear
1
(DOSFAC.BIN)
(180 days)
1
Yes
Scenario
dependent
32
DOSFAC6.BI
N
6 hours
Scenario definition
To consider short-lived radionuclides.
To include shorter-lived radionuclides
in the analysis.
First Input
Basic radiation dose limit (mrem/yr)
Exposure duration (yr)
Number of unsaturated zone
(30)
30
1
25
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8
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
New
Parameter
in
RESRAD-
Offsite ***
RESRAD-Offsite
Default Values
Baseline
Values (if
other than
the default)
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
Comments
Source
Nuclide concentration (pCi/g)
0.0044
Scenario definition. Corresponds to a
soil density of 1.52 g/cm3.
Source Release
Release to groundwater, leach rate
(1/yr)
0
Distribution Coefficients (ml/g)
Contaminated zone
Unsaturated zone
Saturated zone
Sediment in surface water body
Fruit, grain, non-leafy fields
Leafy vegetable fields
Pasture, silage growing areas
V
V
V
V
Nuclide dependent
(see Table A. 1
Baseline Values
and Distributions
for the Kd
Parameter)
Same as above
Same as above
Same as above
Same as above
Same as above
Same as above
Geometric
mean of
distribution
(see Table A. 1
Baseline
Values and
Distributions
for the Kd
Parameter)
Same as above
Same as above
Same as above
Same as above
Same as above
Same as above
Nuclide dependent
(see Table A. 1
Baseline Values and
Distributions for the
Kd Parameter)
Same as above
Same as above
Same as above
Same as above
Same as above
Same as above
O
O
(Jl
in
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in
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O
O
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Gfl
O
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
Livestock feed grain fields
New
Parameter
in
RESRAD-
Offsite ***
V
RESRAD-Offsite
Default Values
Same as above
Baseline
Values (if
other than
the default)
Same as above
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
Same as above
Comments
Transfer Factors
Soil to plant transfer factor
[(PCi/kg)/(pCi/kg)]
Fruit, grain, non-leafy vegetables
Leafy vegetables
Pasture, silage
Livestock feed grain
Intake to animal product transfer
factor
V
V
V
V
Nuclide dependent
(see Table A.2
Baseline Values
and Distributions
for the Plant
Transfer Factor)
Same as above
Same as above
Same as above
Geometric
mean of
distribution
(see Table A.2
Baseline
Values and
Distributions
for the Plant
Transfer
Factor)
Same as above
Same as above
Same as above
Nuclide dependent
(see Table A.2
Baseline Values and
Distributions for the
Plant Transfer
Factor)
Same as above
Same as above
Same as above
RESRAD-Offsite considers different
plant types and accepts different
transfer factors, whereas RESRAD
accepts only one transfer factor that is
used for all plant types.
ft
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8
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
Meat [(pCi/kg)/(pCi/d)]
Milk [(pCi/L)/(pCi/d)]
Water to aquatic food transfer factor
New
Parameter
in
RESRAD-
Offsite ***
RESRAD-Offsite
Default Values
Nuclide dependent
(see Table A. 3
Baseline Values
and Distributions
for the Meat
Transfer Factor)
Nuclide dependent
(see Table A. 4
Baseline Values
and Distributions
for the Milk
Transfer Factor)
Baseline
Values (if
other than
the default)
Geometric
mean of
distribution
(see Table A. 3
Baseline
Values and
Distributions
for the Meat
Transfer
Factor)
Geometric
mean of
distribution
(see Table A. 4
Baseline
Values and
Distributions
for the Milk
Transfer
Factor)
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
Nuclide dependent
(see Table A. 3
Baseline Values and
Distributions for the
Meat Transfer
Factor)
Nuclide dependent
(see Table A. 4
Baseline Values and
Distributions for the
Milk Transfer
Factor)
Comments
O
O
(Ji
in
§
in
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O
O
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Gfl
O
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
Fish [(pCi/kg)/(pCi/L)]
Crustacea [(pCi/kg)/(pCi/L)]
New
Parameter
in
RESRAD-
Offsite ***
RESRAD-Offsite
Default Values
Nuclide dependent
[see Table A. 5
Baseline Values
and Distributions
for the Aquatic
Food (Fish)
Transfer Factor]
Nuclide dependent
Baseline
Values (if
other than
the default)
Geometric
mean of
distribution
[see Table A. 5
Baseline
Values and
Distributions
for the
Aquatic Food
(Fish) Transfer
Factor]
Not used
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
Nuclide dependent
[see Table A. 5
Baseline Values and
Distributions for the
Aquatic Food (Fish)
Transfer Factor]
Nuclide dependent /
Not used
Comments
Reporting Times
Times at which output is reported (yr)
1,3,6,12,30,75,
175, 420, 970
Storage Times
Surface water (d)
Well water (d)
Fruits, grain, and non-leafy vegetables
(d)
Leafy vegetables (d)
1
1
14
1
ft
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Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
Pasture and silage (d)
Livestock feed grain (d)
Meat (d)
Milk (d)
Fish (d)
Crustacea and mollusks (d)
New
Parameter
in
RESRAD-
Offsite ***
V
V
RESRAD-Offsite
Default Values
1
45
20
1
7
7
Baseline
Values (if
other than
the default)
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
Comments
Livestock fodder in RESRAD is
divided into two categories in
RESRAD-Offsite: (1) pasture and
silage, and (2) grain.
Livestock fodder is divided into two
categories in RESRAD-Offsite: (1)
pasture and silage, and (2) grain.
Site Properties
Precipitation (m/yr)
Wind speed (m/s)
1
(2)
4.242**
BoundedLogN(1.44
5,0.2419, 1.4, 13)
Primary Contamination Area Parameters
Contaminated zone and cover
Area of primary contamination
(m2)
Length of contamination parallel
to aquifer flow (m)
(10000)
(100)
404685 (100
acres)
636
(equivalent to
the square root
of area).
O
O
(Jl
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o
o
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UJ
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Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
Depth of soil mixing layer (m)
Deposition velocity of dust (m/s)
Irrigation applied per year (m/yr)
Evapotranspiration coefficient
Runoff coefficient
Rainfall erosion index
Slope-length-steepness factor
Cropping management factor
Conservation practice factor
Contaminated zone
Thickness (m)
Total porosity
New
Parameter
in
RESRAD-
Offsite ***
V
V
V
V
V
RESRAD-Offsite
Default Values
(0.15)
(0.01)
0.2
(0.5)
(0.2)
200
1
0.11
1
(2)
(0.4)
Baseline
Values (if
other than
the default)
0.25*
0.002
0.625*
0.45*
0.15
0.426
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
Triangular(0.0,
0.15,0.6)
Uniform(0.5, 0.75)
Uniform(0. 1,0.8)
Comments
Value decided based on the screening
calculation for air transport in the
earlier version of the Scenarios
chapter.
The parameters is used to calculate
the erosion rate.
The parameter is used to calculate the
erosin rate.
The parameter is used to calculate the
erosin rate.
The parameter is used to calculate the
erosion rate.
Plowing depth.
Value calculated using the dry bulk
density.
ft
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8
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
Erosion rate (m/yr)
Dry bulk density (g/cm3)
Soil credibility factor (tons/acre)
Field capacity
Soil b parameter
Hydraulic conductivity (m/yr)
Clean Cover
Thickness (m)
Total porosity
Erosion rate (m/yr)
New
Parameter
in
RESRAD-
Offsite ***
V
RESRAD-Offsite
Default Values
(0.0009856)
(1.5)
(0.3)
(0.3)
(5.3)
(10)
0
(0.4)
(0.0009856)
Baseline
Values (if
other than
the default)
0
1.52*
0
0.2
2.895**
9.974**
Not used
Not used
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
Continuous Log /
No distribution was
specified in dose
analyses
BoundedLogN(1.06,
0.66, 0.5, 30)
BoundedLogN(2.3,
2.11,0.004,9250)
Comments
The parameter value is calculated by
RESRAD-Offsite using other input
parameters. By specifying a 0
credibility factor, the calculated value
is 0, which was used in dose analysis
to get conservative results. This
parameter is an input parameter in
RESRAD, the default value is 0.001.
A value of 0 was used to get 0 erosion
rate. The parameter is used to
calculate the erosion rate.
Value was decided to keep
consistence with the RESRAD
baseline value.
No cover material.
No cover material. The parameter
value is calculated by
RESRAD-Offsite using other input
parameters.
O
O
(Ji
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Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
Dry bulk density (g/cm3)
Soil credibility factor (tons/acre)
Volumetric water content
New
Parameter
in
RESRAD-
Offsite ***
V
V
RESRAD-Offsite
Default Values
(1.5)
(0.3)
(0.05)
Baseline
Values (if
other than
the default)
Not used
Not used
Not used
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
TruncN(1.52, 0.230,
0.001, 0.999) /not
used
Comments
No cover material.
No cover material. The parameter is
used to calculate the erosion rate.
No cover material.
Unsaturated Zone Parameters
Thickness (m)
Dry bulk density (g/cm3)
Total porosity
Effective porosity
Field capacity
Hydraulic conductivity (m/yr)
Soil b parameter
(4)
(1.5)
(0.4)
(0.2)
(0.3)
(10)
(5.3)
9.895**
1.52*
0.425*
0.355*
0.2
9.974**
2.895**
BoundedLogN(2.29
26, 1.276,0.18,
320)
TruncN(1.52, 0.230,
0.001, 0.999)
TruncN(0.425,
0.0867, 0.001,
0.999)
TruncN(0.355,
0.0906, 0.001,
0.999)
BoundedLogN(2.3,
2.11,0.004,9250)
BoundedLogN(1.06,
0.66, 0.5, 30)
Set to 0.2 to be consistent with the
RESRAD default value.
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Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
Longitudinal dispersivity (m)
New
Parameter
in
RESRAD-
Offsite ***
V
RESRAD-Offsite
Default Values
1
Baseline
Values (if
other than
the default)
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
Comments
Saturated Zone Hydrological Data
Thickness of saturated zone (m)
Dry bulk density of saturated zone
fe/cm3)
Total porosity
Effective porosity
Hydraulic conductivity (m/yr)
Hydraulic gradient
Longitudinal dispersivity (m)
Horizontal lateral dispersivity (m)
Disperse vertically?
Vertical lateral dispersivity (m)
Do not disperse vertically?
Value averaged over length of
saturated zone
Irrigation rate (m/yr)
V
V
V
V
V
V
(100)
(1.5)
(0.4)
(0.2)
(100)
(0.02)
10
3
Yes
1
No
0.2
3000
1.52*
0.425*
0.355*
9.974**
0.00604**
Not used
TruncN(1.52, 0.230,
0.001, 0.999)
TruncN(0.425,
0.0867, 0.001,
0.999)
TruncN(0.355,
0.0906, 0.001,
0.999)
BoundedLogN(2.3,
2.11,0.004,9250)
BoundedLogN(-5 . 1
1, 1.77, 7e-5, 0.5)
Value selected to avoid water
mounding in the saturated zone.
Vertical dispersion was selected.
O
O
(Ji
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o
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6
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O
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
Evapotranspiration coefficient
Runoff coefficient
Depth of aquifer contributing to water
source
Well screen depth (below
groundwater table) (m)
Surface water body (below
groundwater table) (m)
New
Parameter
in
RESRAD-
Offsite ***
V
RESRAD-Offsite
Default Values
0.5
0.2
10
10
Baseline
Values (if
other than
the default)
Not used
Not used
15.33*
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
Triangular(6, 10,
30)
Comments
Agriculture Area Parameters
Fruite, grain, and non-leafy field
Area (m2)
Fraction of area directly over
primary contamination
Irrigation applied per year (m/yr)
Evapotranspiration coefficient
Runoff coefficient
Depth of soil mixing layer or
plow layer (m)
V
V
V
V
V
V
1000
0
0.2
(0.5)
(0.2)
(0.15)
0.625*
0.45*
0.25*
Uniform(0.5, 0.75)
Uniform(0. 1,0.8)
Triangular(0.0,
0.15,0.6)
Scenario definition.
O
E.
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8
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
Total water filled porosity
Erosion rate (m/yr)
Dry bulk density of soil (g/cm3)
Soil credibility factor (tons/acre)
Slope-length-steepness factor
Cropping management factor
Conservation practice factor
Leafy vegetable field
Area (m2)
New
Parameter
in
RESRAD-
Offsite ***
V
V
V
V
V
V
V
V
RESRAD-Offsite
Default Values
0.3
0.0009856
(1.5)
0.3
1
0.11
1
1000
Baseline
Values (if
other than
the default)
1.52*
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
TruncN(1.52, 0.230,
0.001, 0.999)
Comments
In RESRAD, the parameter value is
calculated using the infiltration rate,
saturated hydraulic conductivity, b
parameter, and total porosity. The
saturated hydraulic conductivity, b
parameter, and total porosity are no
longer input parameters for the
agricultural area in RESRAD-Offsite.
The parameter value is calculated by
RESRAD-Offsite using other
parameters. It is an input parameter in
RESRAD and the default value is
0.001.
The parameter is used to calculate the
erosion rate.
The parameter is used to calculate the
erosion rate.
The parameter is used to calculate the
erosion rate.
The parameter is used to calculate the
erosion rate.
O
O
(Ji
in
in
o
fa
o
o
6
UJ
-------
Gfl
O
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
Fraction of area directly over
primary contamination
Irrigation applied per year (m/yr)
Evapotranspiration coefficient
Runoff coefficient
Depth of soil mixing layer or
plow layer (m)
Total water filled porosity
Erosion rate (m/yr)
Dry bulk density of soil (g/cm3)
Soil erodibility factor (tons/acre)
Slope-length-steepness factor
New
Parameter
in
RESRAD-
Offsite ***
V
V
V
V
V
V
V
V
V
V
RESRAD-Offsite
Default Values
0
0.2
(0.5)
(0.2)
(0.15)
0.3
0.0009856
(1.5)
0.3
1
Baseline
Values (if
other than
the default)
0.625*
0.45*
0.25*
1.52*
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
Uniform(0.5, 0.75)
Uniform(0. 1,0.8)
Triangular(0.0,
0.15,0.6)
TruncN(1.52, 0.230,
0.001, 0.999)
Comments
Scenario definition.
In RESRAD, the parameter value is
calculated using the infiltration rate,
saturated hydraulic conductivity, b
parameter, and total porosity. The
saturated hydraulic conductivity, b
parameter, and total porosity are no
longer input parameters for the
agricultural area in RESRAD-Offsite.
The value is calculated by
RESRAD-Offsite using other input
parameters. It is an input parameter in
RESRAD and the default value is
0.001.
The parameter is used to calculate
erosion rate.
The parameter is used to calculate
erosion rate.
"8
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8
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
Cropping management factor
Conservation practice factor
New
Parameter
in
RESRAD-
Offsite ***
V
V
RESRAD-Offsite
Default Values
0.11
1
Baseline
Values (if
other than
the default)
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
Comments
The parameter is used to calculate
erosion rate.
The parameter is used to calculate
erosion rate.
Livestock Feed Growing Area Parameters
Pasture and silage field
Area (m2)
Fraction of area directly over
primary contamination
Irrigation applied per year (m/yr)
Evapotranspiration coefficient
Runoff coefficient
Depth of soil mixing layer or
plow layer (m)
Total water filled porosity
V
V
V
V
V
V
V
10000
0
(0.2)
(0.5)
(0.2)
(0.15)
0.3
0
0.625 *
0.45*
0.25 *
Uniform(0.5, 0.75)
Uniform(0. 1,0.8)
Triangular(0.0,
0.15,0.6)
Scenario definition.
No irrigation for livestock feed
growing area.
In RESRAD, the parameter value is
calculated using the infiltration rate,
saturated hydraulic conductivity, b
parameter, and total porosity. The
saturated hydraulic conductivity, b
parameter, and total porosity are no
longer input parameters for the
agricultural area in RESRAD-Offsite.
O
O
(Ji
>
in
in
o
fa
o
o
6
UJ
-------
Gfl
O
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
Erosion rate (m/yr)
Dry bulk density of soil (g/cm3)
Soil credibility factor (tons/acre)
Slope-length-steepness factor
Cropping management factor
Conservation practice factor
Grain field
Area (m2)
Fraction of area directly over
primary contamination
Irrigation applied per year (m/yr)
Evapotranspiration coefficient
Runoff coefficient
Depth of soil mixing layer or
plow layer (m)
New
Parameter
in
RESRAD-
Offsite ***
V
V
V
V
V
V
V
V
V
V
V
V
RESRAD-Offsite
Default Values
0.0009856
(1.5)
0.3
1
0.11
1
10000
0
(0.2)
(0.5)
(0.2)
(0.15)
Baseline
Values (if
other than
the default)
1.52*
0
0.625*
0.45*
0.25*
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
TruncN(1.52, 0.230,
0.001, 0.999)
Uniform(0.5, 0.75)
Uniform(0. 1,0.8)
Triangular(0.0,
0.15,0.6)
Comments
The value is calculated by
RESRAD-Offsite using other input
parameters. It is an input parameter in
RESRAD and the default value is
0.001.
The parameter is used to calculate
erosion rate.
The parameter is used to calculate
erosion rate.
The parameter is used to calculate
erosion rate.
The parameter is used to calculate
erosion rate.
No irrigation for livestock feed
growing area.
"8
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8
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
Total water filled porosity
Erosion rate (m/yr)
Dry bulk density of soil (g/cm3)
Soil credibility factor (tons/acre)
Slope-length-steepness factor
Cropping management factor
Conservation practice factor
New
Parameter
in
RESRAD-
Offsite ***
V
V
V
V
V
V
V
RESRAD-Offsite
Default Values
0.3
0.0009856
(1.5)
0.3
1
0.11
1
Baseline
Values (if
other than
the default)
1.52*
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
TruncN(1.52, 0.230,
0.001, 0.999)
Comments
In RESRAD, the parameter value is
calculated using the infiltration rate,
saturated hydraulic conductivity, b
parameter, and total porosity. The
saturated hydraulic conductivity, b
parameter, and total porosity are no
longer input parameters for the
agricultural area in RESRAD-Offsite.
The parameter value is calculated by
RESRAD-Offsite using other input
parameters. It is an input parameter in
RESRAD and the default value is
0.001.
The parameter is used to calculate
erosion rate.
The parameter is used to calculate
erosion rate.
The parameter is used to calculate
erosion rate.
The parameter is used to calculate
erosion rate.
O
O
(Ji
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in
o
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o
6
UJ
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O
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
New
Parameter
in
RESRAD-
Offsite ***
RESRAD-Offsite
Default Values
Baseline
Values (if
other than
the default)
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
Comments
Surface Water Body Parameters
Sediment delivery ratio
Volume of surface water body (m3)
Mean residence time of water in
surface water body (y)
V
V
V
(1)
150000
(1)
0.5
9.609 x 10-4
(8.4175 hr)
/ Uniform(0, 1)
Used to determine the amount of
eroded radionuclides getting to the
surface water body.
The surface water body was assumed
to be of a circular shape, with a radius
of 100 m and a depth of 4.77 m in
dose analyses.
The baseline value was calculated
based on the volume of the surface
water body and a flow rate of 4.95
mVsec.
Air Transport Parameters
Chi/Q (s/m3) for fruit, grain, non-leafy
vegetable field
Chi/Q (s/m3) for leafy vegetable field
Chi/Q (s/m3) for pasture and silage
field
Chi/Q (s/m3) for grain field
V
V
V
V
(0)
(0)
(0)
(0)
5.97 x 10-6
5.97 x 10'6
5.97 x 10-6
5.97 x 10'6
Value from CAP88-PC for a distance
of 800 m.
Value from CAP88-PC for a distance
of 800 m.
Value from CAP88-PC for a distance
of 800 m.
Value from CAP88-PC for a distance
of 800 m.
Groundwater Transport Parameters
Distance from downgradient edge of
contamination to
ft
"8
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Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
Well in the direction parallel to
aquifer flow (m)
Surface water body in the
direction parallel to aquifer flow
(m)
Distance from center of contamination
to
Well in the direction
perpendicular to aquifer flow (m)
Near edge of surface water body
in the direction parallel to aquifer
flow (m)
Far edge of surface water body in
the direction parallel to aquifer
flow (m)
Convergence criterion (fractional
accuracy desired)
Number of sub zones (to model
dispersion of progeny produced in
transit)
Main sub zones in saturated zone
Minor sub zones in last main sub
zone in saturated zone
New
Parameter
in
RESRAD-
Offsite ***
V
V
V
V
V
V
V
RESRAD-Offsite
Default Values
(100)
(100)
0
(-125)
(125)
0.001
1
Not used
Baseline
Values (if
other than
the default)
800
800
-100
100
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
Comments
Assumed the well is located at the
center of the established living area.
Assumed the center of the surface
water body is 800 m from the edge of
the primary contaminated area.
Assumed the well is located at the
center of the established living area,
which is located downgradient from
the primary contaminated site.
The surface water body was assumed
to be of a circular shape with a radius
of 100 m.
Same as above.
O
O
(Ji
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Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
Main sub zones in each partially
saturated zone
Minor sub zones in last main sub
zone in each partially saturated
zone
Retardation and dispersion treatment
Nuclide specific retardation in all
sub zones, longitudinal dispersion
in all but the sub zone of
transformation?
Longitudinal dispersion in all sub
zones, nuclide specific retardation
in all but the sub zone of
transformation, parent retardation
in zone of transformation?
Longitudinal dispersion in all sub
zones, nuclide specific retardation
in all but the sub zone of
transformation, progeny
retardation in zone of
transformation?
New
Parameter
in
RESRAD-
Offsite ***
V
V
V
V
V
RESRAD-Offsite
Default Values
1
Not used
Yes
No
No
Baseline
Values (if
other than
the default)
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
Comments
Water Use Parameters
Human consumption
Quantify (L/yr)
(510)
409.5 **
TruncLogN(6.015,
0.489, 0.001, 0.999)
"8
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Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
Fraction of water from surface
body
Fraction of water from well
Number of household individuals
Household purposes
Quantify (L/yr)
Fraction of water from surface
body
Fraction of water from well
Beef cattle
Quantify (L/yr)
Fraction of water from surface
body
Fraction of water from well
Number of cattle
Dairy cows
Quantify (L/yr)
Fraction of water from surface
body
New
Parameter
in
RESRAD-
Offsite ***
V
V
V
V
V
V
RESRAD-Offsite
Default Values
0
(1)
4
225
0
1
50
(0)
(1)
2
160
(0)
Baseline
Values (if
other than
the default)
0.9
0.5
0.5
0.5
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
Comments
Assuming 90% of the drinking water
is from a local well.
Assuming 90% of the drinking water
is from a local well.
The parameter is used to calculate the
total amount of water needed from the
affected area.
The parameter is used to calculate the
total amount of water needed from the
affected area.
O
O
(Ji
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Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
Fraction of water from well
Number of cows
Irrigation applied per year
Fruit, grain, non-leafy vegetables
Quantify (m/yr)
Fraction of water from surface
body
Fraction of water from well
Area of plot (m2)
Leafy vegetables
Quantify (m/yr)
Fraction of water from surface
body
Fraction of water from well
New
Parameter
in
RESRAD-
Offsite ***
V
V
V
V
V
V
V
V
V
RESRAD-Offsite
Default Values
(1)
2
0.2
(0)
(1)
1000
0.2
(0)
rn
Baseline
Values (if
other than
the default)
0.5
0.5
0.5
0.5
0.5
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
Comments
The parameter is used to calculate the
total amount of water needed from the
affected area.
Value should be consistent with the
irrigation rate specified for the same
farmed field.
Value should be consistent with the
size specified for the same farmed
field.
Value should be consistent with the
irrigation rate specified for the same
farmed field.
ft
"8
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Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
Area of plot (m2)
Pasture and silage
Quantify (m/yr)
Fraction of water from surface
body
Fraction of water from well
Area of plot (m2)
Livestock feed grain
Quantify (m/yr)
Fraction of water from surface
body
Fraction of water from well
Area of plot (m2)
New
Parameter
in
RESRAD-
Offsite ***
V
V
V
V
V
V
V
V
V
RESRAD-Offsite
Default Values
1000
(0.2)
(0)
(1)
10000
(0.2)
(0)
(1)
10000
Baseline
Values (if
other than
the default)
0
0.5
0.5
0
0.5
0.5
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
Comments
Value should be consistent with the
size specified for the same farmed
field.
Value should be consistent with the
irrigation rate specified for the same
farmed field.
Value should be consistent with the
size specified for the same farmed
field.
Value should be consistent with the
irrigation rate specified for the same
farmed field.
Value should be consistent with the
size specified for the same farmed
field.
O
O
(Ji
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Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
Well pumping rate (nf/yr)
Well pumping rate needed to specified
water use (mVyr)
New
Parameter
in
RESRAD-
Offsite ***
V
RESRAD-Offsite
Default Values
250
4884.17
Baseline
Values (if
other than
the default)
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
Comments
Value kept consistent with the
baseline value used for RESRAD.
The value was calculated by
RESRAD-Offsite based on the
various water needs specified. It is
listed for reference purposes only.
Ingestion Rates
Consumption rate
Drinking water (L/yr)
Fish (kg/yr)
Other aquatic food (kg/yr)
Fruit, grain, non-leafy vegetables
(kg/yr)
Leafy vegetables (kg/yr)
Meat (kg/yr)
Milk (L/yr)
Soil (incidental) (g/yr)
(510)
(5.4)
(0.9)
(160)
(14)
(63)
(92)
(36.5)
409.5**
155.6*
0
210.33*
22.667*
222.1*
120.67*
18.27*
TruncLogN(6.015,
0.489, 0.001, 0.999)
/ Triangular(2.0,
56.3, 408.5)
Triangular(135,
178,318)
/ Triangular(13, 25,
30)
/ Triangular(5.0,
72.6, 588.7)
Triangular(60, 102,
200)
Triangular(0, 18.3,
36.5)
Baseline distribution from 1997 EPA
Exposure Factors Handbook.
Scenario definition. No ocean fish.
"8
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Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
Fraction from affected area
Drinking water
Fish
Other aquatic food
Fruit, grain, non-leafy vegetables
Leafy vegetables
Meat
Milk
New
Parameter
in
RESRAD-
Offsite ***
RESRAD-Offsite
Default Values
(1)
(0.5)
(0.5)
0.5
0.5
1
1
Baseline
Values (if
other than
the default)
0.9
0.463*
0
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
Triangular(0, 0.39,
1)
Comments
To be consistent with the baseline
value for RESRAD.
Scenario definition. No ocean fish.
Livestock Intakes
Meat Cows
Water (L/d)
Pasture and silage (kg/d)
Grain (kg/d)
V
V
50
14
54
Value kept consistent with the one
specified in "Water Use".
RESRAD-Offsite divides the total
fodder ingestion rate of 68 kg/d used
in RESRAD to pasture and silage
ingestion rate of 14 kg/d and grain
ingestion rate of 54 kg/d.
RESRAD-Offsite divides the total
fodder ingestion rate of 68 kg/d used
in RESRAD to pasture and silage
ingestion rate of 14 kg/d and grain
ingestion rate of 54 ks/d.
O
O
(Ji
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Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
Soil from pasture and silage
(kg/d)
Soil from grain (kg/d)
Milk Cows
Water (L/d)
Pasture and silage (kg/d)
Grain (kg/d)
New
Parameter
in
RESRAD-
Offsite ***
V
V
V
V
RESRAD-Offsite
Default Values
0.1
0.4
160
44
11
Baseline
Values (if
other than
the default)
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
Comments
RESRAD-Offsite divides the
livestock total soil ingestion rate of
0.5 kg/d used in RESRAD to soil
ingestion rate from pasture and silage
of 0. 1 kg/d and soil ingestion rate
from grain of 0.4 kg/d.
RESRAD-Offsite divides the
livestock total soil ingestion rate of
0.5 kg/d used in RESRAD to soil
ingestion rate from pasture and silage
of 0. 1 kg/d and soil ingestion rate
from grain of 0.4 kg/d.
Water kept consistent with the one
specified in "Water Use".
RESRAD-Offsite divides the total
fodder ingestion rate of 55 kg/d used
in RESRAD to pasture and silage
ingestion rate of 44 kg/d and grain
ingestion rate of 1 1 kg/d.
RESRAD-Offsite divides the fodder
ingestion rate of 55 kg/d used in
RESRAD to pasture and silage
ingestion rate of 44 kg/d and grain
ingestion rate of 1 1 ks/d.
"8
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Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
Soil from pasture and silage
(kg/d)
Soil from grain (kg/d)
New
Parameter
in
RESRAD-
Offsite ***
V
V
RESRAD-Offsite
Default Values
0.4
0.1
Baseline
Values (if
other than
the default)
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
Comments
RESRAD-Offsite divides the
livestock total soil ingestion rate of
0.5 kg/d used in RESRAD to soil
ingestion rate from pasture and silage
of 0.4 kg/d and soil ingestion rate
from grain of 0. 1 kg/d.
RESRAD-Offsite divides the
livestock total soil ingestion rate of
0.5 kg/d used in RESRAD to soil
ingestion rate from pasture and silage
of 0.4 kg/d and soil ingestion rate
from grain of 0. 1 kg/d.
Livestock Feed Factors
Pasture and silage
Wet weight crop yield (kg/m2)
Duration of growing season (y)
Foliage to food transfer
coefficient
V
V
V
1.1
0.08
1
RESRAD-Offsite divides fodder into
two categories: (1) pasture and silage,
and (2) grain. Default values for
pasture and silage were set to the
same as those for fodder in RESRAD.
See "wet weight crop yield".
See "wet weight crop yield".
O
O
(Ji
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o
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O
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
Weathering removal constant
(1/yr)
Foliar interception factor for
irrigation
Foliar interception factor for dust
Root depth (m)
Grain
Wet weight crop yield (kg/m2)
Duration of growing season (y)
Foliage to food transfer
coefficient
Weathering removal constant
(1/yr)
Foliar interception factor for
irrigation
Foliar interception factor for dust
New
Parameter
in
RESRAD-
Offsite ***
V
V
V
V
V
V
V
V
V
V
RESRAD-Offsite
Default Values
20
0.25
0.25
0.9
0.7
0.17
0.1
20
0.25
0.25
Baseline
Values (if
other than
the default)
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
Comments
See "wet weight crop yield".
See "wet weight crop yield".
See "wet weight crop yield".
RESRAD uses one root depth (0.9 m)
for all plant categories.
RESRAD-Offsite has different root
depths for different plant categories.
RESRAD-Offsite divides fodder into
two categories: (1) pasture and silage,
and (2) grain. Default values for grain
were set to the same as those for
non-leafy plants in RESRAD.
See "wet weight crop yield".
See "wet weight crop yield".
See "wet weight crop yield".
See "wet weight crop yield".
See "wet weight crop yield".
"8
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Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
Root depth (m)
New
Parameter
in
RESRAD-
Offsite ***
V
RESRAD-Offsite
Default Values
1.2
Baseline
Values (if
other than
the default)
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
Comments
RESRAD uses one root depth (0.9 m)
for all plant categories.
RESRAD-Offsite has different root
depths for different plant categories.
Plant Factors
Fruit, grain, non-leafy
Wet weight crop yield (kg/m2)
Duration of growing season (y)
Foliage to food transfer
coefficient
Weathering removal constant
(1/yr)
Foliar interception factor for
irrigation
Foliar interception factor for dust
Root depth (m)
Leafy vegetables
Wet weight crop yield (kg/m2)
Duration of growing season (y)
V
(0.7)
0.17
0.1
(20)
0.25
0.25
1.2
1.5
0.25
1.751**
35.70*
TruncLogN(0.56,
0.48, 0.001, 0.999)
Triangular(5.1, 18,
84)
RESRAD uses one root depth (0.9 m)
for all plant categories.
RESRAD-Offsite has different root
depths for different plant categories.
O
O
(Ji
in
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in
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fa
O
O
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Gfl
O
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
Foliage to food transfer
coefficient
Weathering removal constant
(1/yr)
Foliar interception factor for
irrigation
Foliar interception factor for dust
Root depth (m)
New
Parameter
in
RESRAD-
Offsite ***
V
RESRAD-Offsite
Default Values
1
20
(0.25)
0.25
0.9
Baseline
Values (if
other than
the default)
0.56*
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
Triangular(0.06,
0.67, 0.95)
Comments
RESRAD uses one root depth (0.9 m)
for all plant categories.
RESRAD-Offsite has different root
depths for different plant categories.
Inhalation and External Gamma Data
Inhalation rate (nrVyr)
Mass loading for inhalation (g/m3)
Mean on-site mass loading (g/m3)
Indoor dust filtration factor
External gamma shielding factor
(8400)
(0.0001)
(0.0001)
(0.4)
(0.7)
8627*
2.45E-05*
2.45E-05
0.55*
0.27**
Triangular(4380,
8400, 13100)
Continuous Linear
Uniform(0.15, 0.95)
BoundedLogN(-1.3,
0.59, 0.044, 1)
External Radiation Shape and Area Factors
Shape of the plane of the primary
contamination
Circular?
Polygonal?
Yes
No
"8
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Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
On-site
Scale (m)
Receptor location X (m):
Receptor location Y (m):
Off-site
Scale (m)
Receptor location X (m):
Receptor location Y (m):
New
Parameter
in
RESRAD-
Offsite ***
V
V
V
RESRAD-Offsite
Default Values
Baseline
Values (if
other than
the default)
not used
not used
not used
2500
2410
1250
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
Comments
The receptor is not located on-site.
The receptor is not located on-site.
The receptor is not located on-site.
Value determined on the basis of the
selected scale, radius of the
contaminated zone, and the receptor
distance (800 m) from the edge of the
contaminated zone.
Value determined on the basis of the
selected scale.
Occupancy Factors
Fraction of time spent on primary
contamination (whether cultivated or
not)
Indoors
Outdoors
Fraction of time spent off-site, within
the range of radiation emanating from
primary contamination (whether
cultivated or not)
(0.5)
0
0
The receptor is not located on-site.
The receptor is not located on-site.
O
O
(Ji
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O
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
Indoors
Outdoors
Fraction of time spent in farmed areas
(including primary and secondary
contaminated areas)
Fruit, grain and non-leafy
vegetable fields
Leafy vegetable fields
Pasture and silage fields
Livestock grain fields
New
Parameter
in
RESRAD-
Offsite ***
V
V
V
V
V
V
RESRAD-Offsite
Default Values
(0)
(0.4)
(0.1)
(0.1)
(0.1)
(0.1)
Baseline
Values (if
other than
the default)
0.651*
0.25
0.0625
0.0625
0. 7135
0.0625
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
Comments
Value selected to be consistent with
the RESRAD baseline value.
Value selected to be consistent with
RESRAD baseline value.
Value was determined by distributing
the outdoor time fractions (25%)
evenly among the four off-site fields.
Value was determined by distributing
the outdoor time fractions (25%)
evenly among the four off-site fields.
Time fraction spent on this field was
determined by distributing the outdoor
time fractions (25%) evenly among
the four off-site fields. A house was
assumed to be collocated with the
field, therefore, the time fraction spent
inside the house was added to the time
fraction spent on the field.
Value was determined by distributing
the outdoor time fractions (25%)
evenly among the four off-site fields.
ft
"8
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Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
New
Parameter
in
RESRAD-
Offsite ***
RESRAD-Offsite
Default Values
Baseline
Values (if
other than
the default)
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
Comments
Radon Data
Effective radon diffusion coefficient
of cover (m2/s)
Effective radon diffusion coefficient
of contaminated zone (nf/s)
Effective radon diffusion coefficient
of floor (m2/s)
Thickness of floor and foundation (m)
Density of floor and foundation (m)
Total porosity of floor and foundation
Volumetric water content of floor and
foundation
Depth of foundation below ground
level (m)
Radon vertical dimension of mixing
(m)
Building room height (m)
Building air exchange rate (1/h)
Building indoor area factor
Rn-222 emanation coefficient
Rn-220 emanation coefficient
2 x lO'6
3 x 10'7
0.15
2.4
0.1
0.03
-1
2
2.5
0.5
0
0.25
0.15
not used
not used
not used
not used
not used
not used
not used
not used
not used
not used
not used
not used
not used
not used
The house is not constructed on the
primary contamination area.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
O
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in
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in
o
fa
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-------
Gfl
O
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
New
Parameter
in
RESRAD-
Offsite ***
RESRAD-Offsite
Default Values
Baseline
Values (if
other than
the default)
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
Comments
C-14 Data
Thickness of evasion layer for C-14 in
soil (m)
C-14 evasion flux rate from soil
C-12 evasion flux rate from soil
Fraction of vegetation carbon
absorbed from soil
Fraction of vegetation carbon
absorbed from air
User selected inhalation DCF for
C-14/DCF for CO2
0.3
7 x ID'7
1 x lO'10
0.02
0.98
88.9
0.367*
Triangular(0.2, 0.3,
0.6)
Mass Fraction of C-12
Contaminated soil
Local water
Fruit, grain, non-leafy vegetables
Leafy vegetables
Pasture and silage
Grain
Meat
Milk
V
V
0.03
0.00002
0.4
0.09
0.09
0.4
0.24
0.07
Tritium Data
Humidity in air (g/m3 )
(8)
7.243**
TruncLogN(1.98,
0.334, 0.001, 0.999)
"8
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21
8
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)
Input Parameters
Mass fraction of water in
Fruit, grain and non-leafy
vegetables
Leafy vegetable
Pasture and silage
Grain
Meat
Milk
New
Parameter
in
RESRAD-
Offsite ***
V
V
V
V
V
V
RESRAD-Offsite
Default Values
0.8
0.8
0.8
0.8
0.6
0.88
Baseline
Values (if
other than
the default)
NUREG/CR-6697
Probabilistic
Distribution/
Baseline
Distributions (if
other than
NUREG/CR-6697)
Comments
In RESRAD, it is hard wired in the
code.
In RESRAD, it is hard wired in the
code.
In RESRAD, it is hard wired in the
code.
In RESRAD, it is hard wired in the
code.
In RESRAD, it is hard wired in the
code.
In RESRAD, it is hard wired in the
code.
O
O
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Table A.10 RESRAD-Offsite Baseline Parameter Correlations for Probabilistic Analyses
Parameter 1
Including all the correlations in Table A. 8 and the
followings
Kd of Co-57 in sediment of surface water body
Kd of Co-57 in fruit, grain, non-leafy fields
Kd of Co-57 in leafy vegetable fields
Kd of Co-57 in pasture, silage growing areas
Kd of Co-57 in livestock feed grain fields
Kd of Cs-134 in sediment of surface water body
Kd of Cs-134 in fruit, grain, non-leafy fields
Kd of Cs-134 in leafy vegetable fields
Kd of Cs-134 in pasture, silage growing areas
Kd of Cs-134 in livestock feed grain fields
Kd of 1-125 in sediment of surface water body
Kd of 1-125 in fruit, grain, non-leafy fields
Kd of 1-125 in leafy vegetable fields
Kd of 1-125 in pasture, silage growing areas
Kd of 1-125 in livestock feed grain fields
Kd of Pu-238 in sediment of surface water body
Parameter 2
Kd of Co-60 in sediment of surface water body
Kd of Co-60 in fruit, grain, non-leafy fields
Kd of Co-60 in leafy vegetable fields
Kd of Co-60 in pasture, silage growing areas
Kd of Co-60 in livestock feed grain fields
Kd of Cs-137 in sediment of surface water body
Kd of Cs-137 in fruit, grain, non-leafy fields
Kd of Cs-137 in leafy vegetable fields
Kd of Cs-137 in pasture, silage growing areas
Kd of Cs-137 in livestock feed grain fields
Kd of 1-13 1 in sediment of surface water body
Kd of 1-13 1 in fruit, grain, non-leafy fields
Kd of 1-13 1 in leafy vegetable fields
Kd of 1-13 1 in pasture, silage growing areas
Kd of 1-13 1 in livestock feed grain fields
Kd of Pu-239 in sediment of surface water body
Correlation
Coefficient
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
Comments
To ensure the same Kd value
was used by different isotopes of
the same element.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
ft
"8
3
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o*
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21
8
Table A.10 RESRAD-Offsite Baseline Parameter Correlations for Probabilistic Analyses (continued)
Parameter 1
Kd of Pu-238 in fruit, grain, non-leafy fields
Kd of Pu-238 in leafy vegetable fields
Kd of Pu-238 in pasture, silage growing areas
Kd of Pu-238 in livestock feed grain fields
Kd of Ra-226 in sediment of surface water body
Kd of Ra-226 in fruit, grain, non-leafy fields
Kd of Ra-226 in leafy vegetable fields
Kd of Ra-226 in pasture, silage growing areas
Kd of Ra-226 in livestock feed grain fields
Kd of Sr-89 in sediment of surface water body
Kd of Sr-89 in fruit, grain, non-leafy fields
Kd of Sr-89 in leafy vegetable fields
Kd of Sr-89 in pasture, silage growing areas
Kd of Sr-89 in livestock feed grain fields
Kd of Th-228 in sediment of surface water body
Kd of Th-228 in fruit, grain, non-leafy fields
Kd of Th-228 in leafy vegetable fields
Kd of Th-228 in pasture, silage growing areas
Kd of Th-228 in livestock feed grain fields
Parameter 2
Kd of Pu-239 in fruit, grain, non-leafy fields
Kd of Pu-239 in leafy vegetable fields
Kd of Pu-239 in pasture, silage growing areas
Kd of Pu-239 in livestock feed grain fields
Kd of Ra-228 in sediment of surface water body
Kd of Ra-228 in fruit, grain, non-leafy fields
Kd of Ra-228 in leafy vegetable fields
Kd of Ra-228 in pasture, silage growing areas
Kd of Ra-228 in livestock feed grain fields
Kd of Sr-90 in sediment of surface water body
Kd of Sr-90 in fruit, grain, non-leafy fields
Kd of Sr-90 in leafy vegetable fields
Kd of Sr-90 in pasture, silage growing areas
Kd of Sr-90 in livestock feed grain fields
Kd of Th-229 in sediment of surface water body
Kd of Th-229 in fruit, grain, non-leafy fields
Kd of Th-229 in leafy vegetable fields
Kd of Th-229 in pasture, silage growing areas
Kd of Th-229 in livestock feed grain fields
Correlation
Coefficient
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
Comments
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
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Table A.10 RESRAD-Offsite Baseline Parameter Correlations for Probabilistic Analyses (continued)
Parameter 1
Kd of Th-228 in sediment of surface water body
Kd of Th-228 in fruit, grain, non-leafy fields
Kd of Th-228 in leafy vegetable fields
Kd of Th-228 in pasture, silage growing areas
Kd of Th-228 in livestock feed grain fields
Kd of Th-228 in sediment of surface water body
Kd of Th-228 in fruit, grain, non-leafy fields
Kd of Th-228 in leafy vegetable fields
Kd of Th-228 in pasture, silage growing areas
Kd of Th-228 in livestock feed grain fields
Kd of Tl-201 in sediment of surface water body
Kd of Tl-201 in fruit, grain, non-leafy fields
Kd of Tl-201 in leafy vegetable fields
Kd of Tl-201 in pasture, silage growing areas
Kd of Tl-201 in livestock feed grain fields
Kd of U-233 in sediment of surface water body
Kd of U-233 in fruit, grain, non-leafy fields
Kd of U-233 in leafy vegetable fields
Kd of U-233 in pasture, silage growing areas
Parameter 2
Kd of Th-230 in sediment of surface water body
Kd of Th-230 in fruit, grain, non-leafy fields
Kd of Th-230 in leafy vegetable fields
Kd of Th-230 in pasture, silage growing areas
Kd of Th-230 in livestock feed grain fields
Kd of Th-232 in sediment of surface water body
Kd of Th-232 in fruit, grain, non-leafy fields
Kd of Th-232 in leafy vegetable fields
Kd of Th-232 in pasture, silage growing areas
Kd of Th-232 in livestock feed grain fields
Kd of Tl-202 in sediment of surface water body
Kd of Tl-202 in fruit, grain, non-leafy fields
Kd of Tl-202 in leafy vegetable fields
Kd of Tl-202 in pasture, silage growing areas
Kd of Tl-202 in livestock feed grain fields
Kd of U-234 in sediment of surface water body
Kd of U-234 in fruit, grain, non-leafy fields
Kd of U-234 in leafy vegetable fields
Kd of U-234 in pasture, silage growing areas
Correlation
Coefficient
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
Comments
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
ft
"8
3
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o
>
oo
o*
fa
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21
8
Table A.10 RESRAD-Offsite Baseline Parameter Correlations for Probabilistic Analyses (continued)
Parameter 1
Kd of U-233 in livestock feed grain fields
Kd of U-233 in sediment of surface water body
Kd of U-233 in fruit, grain, non-leafy fields
Kd of U-233 in leafy vegetable fields
Kd of U-233 in pasture, silage growing areas
Kd of U-233 in livestock feed grain fields
Kd of U-233 in sediment of surface water body
Kd of U-233 in fruit, grain, non-leafy fields
Kd of U-233 in leafy vegetable fields
Kd of U-233 in pasture, silage growing areas
Kd of U-233 in livestock feed grain fields
Parameter 2
Kd of U-234 in livestock feed grain fields
Kd of U-235 in sediment of surface water body
Kd of U-235 in fruit, grain, non-leafy fields
Kd of U-235 in leafy vegetable fields
Kd of U-235 in pasture, silage growing areas
Kd of U-235 in livestock feed grain fields
Kd of U-238 in sediment of surface water body
Kd of U-238 in fruit, grain, non-leafy fields
Kd of U-238 in leafy vegetable fields
Kd of U-238 in pasture, silage growing areas
Kd of U-238 in livestock feed grain fields
Correlation
Coefficient
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
Comments
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
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O
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-------
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Table A.11 RESRAD-BUILD Baseline Parameter Values and Distributions
Input Parameters
RESRAD-BUILD
Default Values
Baseline Values
(if other than
the default)
NUREG/CR-6697
Probabilistic Distributions /
Baseline Distributions (if
other than NUREG/CR-
6697)
Comments for Baseline
Values/Distributions
Case
Title
Input File
Default case for
RESRAD-Build
Site 1. bid
Scenario
dependent
Scenario
dependent
Scenario definition
Time Parameters
Exposure Duration (d)
Indoor Fraction
Time for Calculation (yr)
Max. No. of Points for Time Integration
365
0.5
1
257
0.651**
Continuous Linear
Not used due to scenario-specific
values.
Building Parameters
Number of Rooms
Deposition Velocity (m/s)
Resuspension Rate (1/s)
1
(0.01)
(5.0E-7)
3.9E-4**
1.3E-6**
LogU(2.7E-6, 2.7E-3)
LogU(2.8E-10, 1.4E-5)
Air Flow
Building Air Exchange Rate (1/h)
(0.8)
1.52**
TruncLogN(0.4187, 0.88,
0.001,0.999)
"8
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21
8
Table A.11 RESRAD-BUILD Baseline Parameter Values and Distributions (continued)
Input Parameters
Area of Room (m2)
Height (m)
RESRAD-BUILD
Default Values
(36)
2.5
Baseline Values
(if other than
the default)
150
2.5
NUREG/CR-6697
Probabilistic Distributions /
Baseline Distributions (if
other than NUREG/CR-
6697)
Triangular(2.4, 3.7, 9.1)/No
distribution
Comments for Baseline
Values/Distributions
Larger than biosolids loading
source area.
Radiological Units
Activity
Dose
pCi
mrem
Receptor Parameters
Receptor No.
Room No.
Time Fraction
Breathing Rate (mVd)
Ingestion Rate (nf/h)
Location (m)
1
1
1
(18)
(0.0001)
(1, 1, 1)
30.5*
0
(0, 5.6, 1)
Triangular(12, 33.6, 46)
LogU(2.8E-5, 2.9E-4)/No
distribution
This distribution represents workers
in an occupational setting
Good hygiene habit.
Shielding Parameter
Source 11 Receptor 1
Thickness (cm)
0
Triangular( 0, 0, 30)
No shielding considered.
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Table A.11 RESRAD-BUILD Baseline Parameter Values and Distributions (continued)
Input Parameters
Density (g/cc)
Material
RESRAD-BUILD
Default Values
2A
Concrete
Baseline Values
(if other than
the default)
NUREG/CR-6697
Probabilistic Distributions /
Baseline Distributions (if
other than NUREG/CR-
6697)
Uniform (2.2, 2.6)
Comments for Baseline
Values/Distributions
Source Parameters For Source 1 in Room 1
Type
Direction
Location (m)
Area (m2)
Air Release Fraction
Direct Ingestion (g/h)
Number of Wall Regions
Material Type
Wall Region Parameters for Region 1
Thickness (cm)
Density (g/cc)
Erosion (cm/d)
Volume
(X)
0,0,0
(36)
0.1
0
1
Concrete
(15)
(2.4)
2.4E-8
Z
100
0.357
50
1.52
1.87e-7*
Triangular(lE-6., 0.07, 1)
Triangular(0,0,5.6E-7)
Only for a line, surface, and volume
source.
Parameter used for a volume or an
area source.
Unit for a point, line, or surface
source is (1/h).
Only for a volume source.
Only for a volume source.
Only for a volume source.
Density for dry biosolid material.
"8
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21
8
Table A.11 RESRAD-BUILD Baseline Parameter Values and Distributions (continued)
Input Parameters
Radon Diffusion Coefficient (nf/s)
Porosity
Radon Emanation Fraction
Radionuclide Concentration (pCi/g)
Tritium Parameters
Area (m2)
Wet+Dry Zone Thickness (cm)
Dry Zone Thickness (cm)
Volumetric Water Content
Water Fraction Available for
Evaporation
Total Porosity of Contaminated
Material
Density of Material (g/cm3)
Humidity (g/m3)
RESRAD-BUILD
Default Values
2.0E-5
(0.1)
0.2
(1.0forCo-60)
(36)
(10)
0
0.03
1
(0.1)
(2.4)
(8)
Baseline Values
(if other than
the default)
0.4
1.0 for all the
radionuclides of
concern
100
50
0.35
0.75
0.4
1.52
9.8*
NUREG/CR-6697
Probabilistic Distributions /
Baseline Distributions (if
other than NUREG/CR-
6697)
Triangular(0.5, 0.75, 1)
Uniform (6.5, 13.1)
Comments for Baseline
Values/Distributions
Total activity (pCi) is needed for a
point source. Unit for a line source
is pCi/m, for an area source is
pCi/m2.
Only for a volume source.
Value should be less than the total
porosity.
This distribution represents
humidity inside the building
O
O
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O
Table A.11 RESRAD-BUILD Baseline Parameter Values and Distributions (continued)
Input Parameters
Erosion Rate (cm/d)
Direct Ingestion Rate (g/h)
Air Release Fraction
Deposition velocity (m/s)
RESRAD-BUILD
Default Values
2.4E-8
0
0.1
(0.01)
Baseline Values
(if other than
the default)
1.87e-7*
0.357
0
NUREG/CR-6697
Probabilistic Distributions /
Baseline Distributions (if
other than NUREG/CR-
6697)
Triangular(0,0,5.6E-7)
Triangular(lE-6., 0.07, 1)
Comments for Baseline
Values/Distributions
Good hygiene habit.
* * Geometric mean value of the distribution
* Mean value of the distribution
( ) RESRAD-BUILD default value not used as baseline value
"8
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Appendix B
RESRAD and RESRAD-BUILD Codes
-------
-------
B.1 Introduction
RESRAD and RESRAD-BUILD are two multimedia computer codes developed by Argonne
National Laboratory (Argonne) under sponsorship of the U.S. Department of Energy (DOE) and
U.S. Nuclear Regulatory Commission (NRC) for use in evaluating radioactively contaminated
sites and buildings, respectively. Both codes have been widely used in the United States and
abroad (Yu, 1999). The RESRAD code (Yu et al., 2001) implements the methodology described
in DOE's manual for developing residual radioactive material guidelines and calculates radiation
dose and excess lifetime cancer risk to a chronically exposed individual at a site with residual
contamination. The RESRAD-BUILD code (Yu et al., 1994) is a pathway analysis model
designed to evaluate the potential radiological dose to an individual who works or lives in a
building contaminated with radioactive material.
The RESRAD code focuses on radioactive contaminants in soil and their transport in air, water,
and biological media to a single receptor. Nine exposure pathways are considered in RESRAD:
(1) direct exposure; inhalation of (2) particulates and (3) radon; and ingestion of (4) plant foods,
(5) meat, (6) milk, (7) aquatic foods, (8) water, and (9) soil. Figure B.I illustrates conceptually
the exposure pathways considered in RESRAD. RESRAD calculates time-integrated annual
dose, soil cleanup guidelines, radionuclide concentrations, and lifetime cancer risks as a function
of time. The code estimates at which time the peak dose occurs for each radionuclide and for all
radionuclides summed. The RESRAD code permits sensitivity analysis for various parameters.
Graphics are used to show the sensitivity analysis and probabilistic results. Text reports are
provided for users to view the deterministic and probabilistic analysis results through a text
viewer.
Final, February 2005 B-l ISCORS Technical Report 2004-03
-------
Source
Environmental
Pathway
Exposure
Pathway
Dose or
Cancer Risk
Residual
Radioactive
Material
In Soil
On-Site
^1 Direct Exposure
On-Site Air
Concentration
Dust/
H-3
Radon
External
Radiation
On-Site Biotic Contamination
Plant Foods
Livestock
Meat
Milk
Aquatic
Foods
Inhalation
On-Site Water
Contamination
On-Site Soil
Contamination
Ingestion
Effective
Dose
Equivalent/
Excess
Cancer Risk
to an
Exposed
Individual
ff
Figure B.I. Graphical Representation of Pathways Considered in RESRAD
The RESRAD-BUTLD code can model a building with up to 3 rooms or compartments,
10 distinct source locations, 4 source geometries, 10 receptor locations, and 8 shielding
materials. A shielding material can be specified between each source-receptor pair for external
gamma dose calculations. The RESRAD-BUTLD code considers the releases of radionuclides
into the indoor air by diffusion, mechanical removal, or erosion. Seven exposure pathways are
considered in RESRAD-BUTLD: (1) external exposure directly from the source; (2) external
exposure to materials deposited on the floor; (3) external exposure due to air submersion;
(4) inhalation of airborne radioactive particulates; (5) inhalation of aerosol indoor radon
progeny; (6) inadvertent ingestion of radioactive material directly from the sources; and
(7) inadvertent ingestion of materials deposited on the surfaces of the building rooms or
furniture. Figure B.2 conceptually illustrates the exposure pathways considered in
RESRAD-BUILD. An air quality model in RESRAD-BUILD evaluates the transport of
radioactive dust particulates, tritium, and radon progeny due to (1) air exchange between rooms
and with outdoor air, (2) the deposition and resuspension of particulates, and (3) radioactive
decay and ingrowth. RESRAD-BUILD has a graphic (3-D display) interface to show the relative
positions and shapes of sources and receptors. A text report is provided that contains the
deterministic and probabilistic analysis results.
ISCORS Technical Report 2004-03
B-2
Final, February 2005
-------
RESRAD-BUILD Pathways
Pathway
Inhalation
External Gamma
Ingestion
Figure B.2. Graphical Representation of Pathways Considered in RESRAD-BUILD
The RESRAD and RESRAD-BUILD codes have been widely used, and many supporting
documents are available, including benchmarking, verification, and validation documents
(Camus et al., 1999; Cheng et al., 1995; Yu, 1999; Yu and Gnanapragasam, 1995; Halliburton
NUS Corp., 1994; Faillace et al., 1994; IAEA, 1996; Laniak et al., 1997; Mills et al., 1997; Seitz
et al., 1994; Whelan et al., 1999a, 1999b; Gnanapragasam and Yu, 1997a, 1997b; BIOMOVS II,
1996; Regens, 1998; Yu et al., 1993a). Both codes have been approved for use by many Federal
and State agencies (Yu, 1999).
Final, February 2005
B-3
ISCORS Technical Report 2004-03
-------
| Uncertainty Analysis Input Summary H|
Sample specifications | Parameter distributions | Input Rank Correlations | Output specifications
Variable Description •»•
Well pump intake depth
Thickness of Unsaturated zone 1
Density of Unsaturated zone 1
Total Porosity of Unsaturated zone 1
Effective Porosity of Unsaturated zone
Hydraulic Conductivity of Unsaturated zc
b Parameter of Unsaturated zone 1
Inhalation rate
Mass loading for inhalation
Indoor dust filtration factor
II External gamma shielding factor i
Indoor time fraction
Fruit, vegetable, and grain consumption
Milk consumption
Soil ingestion
Drinking water intake
Aquatic food
Depth of soil mixing layer
Depth of roots
Wet weight crop yield of fruit, grain and
Weathering removal constant of all
Wet foliar interception fraction of leafy —
External gamma shielding factor
Distribution BOUNDED LOGNORMAL-N jj Default
Mean (Mu) of underlying normal -1.3
Standard deviation (Sigma] of underlying normal .59
Minimum .044
Maximum 1
Previous parameter r,£r,\
Next parameter ^JF'I
parser Hel" Restore Default
(* Perform uncertainty analysis f " Suppress uncertainty analysis this session OK
Figure B.3. Parameter Distribution Input Screen
B.2 Probabilistic Modules
B.2.1 Overview
The probabilistic RESRAD and RESRAD-BUILD codes are extended and enhanced from the
deterministic RESRAD and RESRAD-BUILD codes. A pre-processor and a post-processor are
incorporated into the RESRAD and RESRAD-BUILD codes to facilitate analysis of the effects
of uncertainty in or the probabilistic nature of input parameters in the model. A standard Monte
Carlo method or a modified Monte Carlo method, that is, LHS (McKay et al., 1979), can be
applied to generate random samples of input parameters. Each set of input parameters is used to
generate one set of output results. Figure B.3 shows a typical parameter distribution input screen
that allows the user to view and edit all currently specified parameter distributions for
probabilistic analysis. Once the distribution statistics are specified, the user can click the help
button and the distribution will be shown on the screen, as shown in Figure B.4.
ISCORS Technical Report 2004-03
B-4
Final, February 2005
-------
Help on Statistical distributions
2.95
2.21 - -
1.48--
0.73S
0.455
0.866
1.28
1.68
There are four ways of specifying a
lo gnorm al di stnbutio n with the tails
cut off, "bounded lognormal",
"bounded lognormal-N", "truncated
lognormal" and "truncated lognormal -
N". The relationship between the sets
o f d efinmg p ararn eters are
li= \nM- a-2 II
0-= (\nEF)/l.645
Min= VL
Max= V,
T_Tq
The pdfis
-exp
2\
Uq- Lq
Conditions
0 < Standard deviation (Sigma) of underlying normal distribution
The sample values are obtained in the segment of the distribution Bounded by the specified minimum and
maximum values where
0 < Minimum and Mean - 4.75 * Standard deviation <= Minimum < Maximum <= Mean + 4.75 * Standard
deviation
Close Help Window
Figure B.4. Parameter Distribution Help Screen
The results from all input samples are analyzed and presented in a statistical format in terms of
the average value, standard deviation, minimum value, and maximum value. The cumulative
probability distribution of the output is presented in tabular and graphic forms. Scatter plots of
dose against the probabilistic inputs and temporal plots of dose statistics can be viewed.
Regression methods can be applied to find the correlation of the resultant doses with the input
parameters. Partial correlation coefficients (PCCs), partial rank correlation coefficients
(PRCCs), standardized partial regression coefficients (SPRCs), and standardized partial rank
regression coefficients (SPRRCs) are computed and ranked to provide a tool for determining the
relative importance of input parameters in influencing the resultant dose.
B.2.2 Sampling Method
Samples of the input parameters are generated with an updated version of the LHS computer
code (Iman and Shortencarier, 1984). The uncertainty input form of the user interface collects
all the data necessary for the sample generation and prepares the input file for the LHS code.
When the code is executed (run), the LHS code will be called if the user has requested a
probabilistic/uncertainty analysis. Table B. 1 lists the input data and information needed for
sample generation.
Final, February 2005
B-5
ISCORS Technical Report 2004-03
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Table B.1 Listing of Input Data and Information Needed for Sample
Generation
Input Data
Sampling Parameters
Random Seed
Number of Observations
Number of Repetitions
Sampling Techniques
Latin Hypercube
Simple Random (Monte
Carlo)
Grouping of Observations
Correlated or
Uncorrelated
Random
Statistical Distributions
Statistical Distribution
and Statistical Parameters
Input Rank Correlations
Variable 1, Variable 2
Rank Correlation
Coefficient
Description
Determines the sequence of random numbers generated. This
ensures that the same set of observations is produced when the
given input file is run on different computers, or when an input
file is run at different times on the same computer
Number of sample values to be generated for each input variable
for each repetition. The maximum number allowed is 2001
Number of times probabilistic analysis is repeated.
The distribution to be sampled is split into a number of equally
probable distribution segments, the number being equal to the
desired number of observations. A single observation is obtained
from each segment
The desired number of observations is obtained at random from
the whole distribution.
The samples of each variable are grouped together according to
the specified correlations. The grouping ensures that the
variables for which correlations were not specified are
uncorrelated
The samples of each variable are grouped together at random.
Some pairs of variables may be correlated just by chance.
The statistical distribution and its parameters define the set of
observations to be generated for a probabilistic variable. The
statistical distribution has to be one of the 34 distributions
available in the code. The parameters that have to be specified
depend on the selected distribution and have to satisfy the
conditions of the distribution. These conditions are given in the
help screen (Figure B.5). The input interface will check that
these are satisfied when the user completes inputting the
parameters.
Two variables for which rank correlation is specified
The specified input rank correlation coefficient between two
variables
ISCORS Technical Report 2004-03
B-6
Final, February 2005
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The input data required for sample generation are divided in three categories: (1) sampling
specifications data, (2) statistical distributions data, and (3) input rank correlation data. The
input data and information needed for the sample generation include the initial seed value for the
random number generator, the number of observations (Nobs), the number of repetitions (Nrep), the
sampling technique, the method of grouping the samples generated for the different parameters,
the type of statistical distribution for each input parameter, the parameters defining each of the
distributions, and any correlations between input parameters.
Two sampling techniques are available, LHS and simple random (Monte Carlo) sampling (SRS).
The LHS technique is an enhanced, stratified sampling scheme developed by McKay et al.
(1979). It divides the distribution of each input parameter into Nobs nonoverlapping regions of
equal probability. One sample value is obtained at random (using the current random seed) from
each region on the basis of the probability density function for that region. Each time a sample
is obtained, a new random seed for use in the next region is also generated by using the current
random seed. The sequence of random seeds generated in this manner can be reproduced if there
is ever a need to regenerate the same set of samples. After a complete set of Nobs samples of one
probabilistic/uncertain parameter has been generated, the same procedure is repeated to generate
the samples for the next parameter.
The Monte Carlo sampling, or SRS, technique also obtains the Nobs samples at random; however,
it picks out each sample from the entire distribution using the probability density function for the
whole range of the parameter. Report No. 100 of the International Atomic Energy Agency safety
series (IAEA, 1989) discusses the advantages of the two sampling techniques.
The Nobs samples generated for each probabilistic/uncertain parameter must be combined to
produce Nobs sets of input parameters. Two methods of grouping (or combining) are
available—random grouping or correlated/uncorrelated grouping. Under the random grouping,
the Nobs samples generated for each parameter are combined randomly to produce (Nobs) sets of
inputs. For Nvar probabilistic/uncertain parameters, there are (Nobs!)ways of combining the
samples. It is possible that some pairs of parameters may be correlated to some degree in the
randomly selected grouping, especially if Nobs is not sufficiently larger than Nobs.
In the correlated/uncorrelated grouping, the user specifies the degree of correlation between each
correlated parameter by inputting the correlation coefficients between the ranks of the
parameters. The pairs of parameters for which the degree of correlation is not specified are
treated as being uncorrelated. The code checks whether the user-specified rank correlation
matrix is positive definite and suggests an alternative rank correlation matrix if necessary. It
then groups the samples so that the rank correlation matrix is as close as possible to the one
specified. Both matrices are in the LHS.REP file (which is generated by the RESRAD or
RESRAD-BUTLD code after the probabilistic analysis is run), and the user should examine the
matrices to verify that the grouping is acceptable.
Iman and Helton (1985) suggest ways of choosing the number of samples for a given situation.
The minimum and maximum doses and risk vary with the number of samples chosen. The
accuracies of the mean dose and of the dose values for a particular percentile are dependent on
the percentile of interest and on the number of samples. The confidence interval or the (upper or
lower) confidence limit of the mean can be determined from the results of a single set of
Final, February 2005 B-7 ISCORS Technical Report 2004-03
-------
samples. Distribution-free upper (u%, v%) statistical tolerance limits can be computed by using
the SRS technique according to the methodology in IAEA Report No. 100 (IAEA, 1989).
B.2.3 Distribution of Parameters
A set of input parameters for uncertainty analysis is chosen through the code's interface. Each
parameter chosen must have a probability distribution assigned to it and may be correlated with
other input parameters included in the uncertainty analysis. Thirty-four different distribution
types are available for selection. The statistical parameters required depend on the distribution,
and the appropriate input fields are displayed when a distribution is selected. The conditions to
be satisfied by these statistical parameters are given in the help screen (Figure B.4). The
interface checks whether the statistical parameters satisfy the conditions when the user inputs
them, and it emphasizes ("red flags") any statistical parameters that violate the conditions.
Different distribution types and the required distribution data can be found in NUREG/CR-6697
(Yu et al., 2000). The input parameters can be correlated by specifying a pairwise rank
correlation matrix. The induced correlation is applied to the ranks of the parameters; hence, the
name "rank correlation" is given.
B.2.4 Probabilistic Results
The results of the probabilistic analysis handled by the post-processor are presented in the
summary text files.
The interactive output provides graphical and tabular results for peak pathway doses, for peak
nuclide doses, and for dose at user times for any pathway-nuclide combination in RESRAD. In
RESRAD-BUTLD, it provides results for dose to each receptor, via each or all pathways, at each
user time, from either each or all nuclides in each source or from all sources. The tabular results
provided are the minimum, maximum, mean, standard deviation, and the percentile values in
steps of 5%, as well as their 95% confidence range where appropriate. Scatter against the
probabilistic inputs and cumulative probability plots are available in both RESRAD and
RESRAD-BUILD. In addition, RESRAD has temporal plots of the mean, 90%, and 95% of total
dose.
Printable results are available in the text files. In each case, the file contains statistical data for a
collection of resultant doses as a function of user time, pathway, radionuclide, source, and
receptor, as appropriate. The statistical data provided for the resultant dose include the average
value, standard deviation, minimum value, and maximum value. The cumulative probability
distribution of the resultant dose is presented in a tabular form in terms of percentile values in
steps of 2.5%. Separate tables are provided for each repetition in RESRAD, giving the
minimum, maximum, mean, median, and the 90th-percentile, 95th-percentile, 97.5th-percentile,
and the 99th-percentile of total dose (summed over nuclides and pathways) at graphical times. A
single table summarizes the peak of the mean total dose for all observations and the time of the
same for each repetition.
Tabulations are provided of the correlation of the resultant doses with the input parameters as
computed by regression methods. The input parameters are ranked according to their relative
importance and their contribution to the overall uncertainty. The parameter ranks and
correlations are discussed in detail in NUREG/CR-6676 (Kamboj et al., 2000).
ISCORS Technical Report 2004-03 B-8 Final, February 2005
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Although the RESRAD and RESRAD-BUILD codes provide easy-to-use, user-friendly
interfaces for probabilistic analysis, users need to employ this feature with caution. The saying
"garbage in, garbage out" is not only true for the deterministic codes, it is especially true for the
probabilistic codes. As a matter of fact, because there are more parameters (such as distribution
characteristic parameters) in the probabilistic codes, users need to obtain more information on
the site and perhaps need to better characterize the site to ensure properly modeling.
The probabilistic versions of the RESRAD and RESRAD-BUILD codes provide tools for
studying the uncertainty in dose assessment caused by uncertainty in the input parameters.
Although the codes are designed to be user-friendly, they must be used with caution, and it is
important that users be properly trained and that sufficient site-specific (probabilistic) data be
collected for input into the codes.
B.3 References
BIOMOVS II Steering Committee. "Long-Term Contaminant Migration and Impacts from
Uranium Mill Tailings—Comparison of Computer Models Using a Realistic Dataset."
Stockholm, Sweden: Swedish Radiation Protection Institute; BIOMOVS II Technical Report
No. 5. Aug. 1996.
Camus, H., et al. "Long-Term Contaminant Migration and Impacts from Uranium Mill
Tailings." J. Environ. Rad., 42:289-304. 1999.
Cheng, J.-J. et al. "Benchmarking Analysis of Three Multimedia Models: RESRAD,
MMSOILS, and MEPAS." Washington, DC: U.S. Department of Energy; DOE/ORO-2033.
1995.
Faillace, E.R., Cheng, J.-J., and Yu, C. "RESRAD Benchmarking against Six Radiation
Exposure Pathway Models." Argonne, IL.: Argonne National Laboratory. ANL/EAD/TM-24.
1994.
Gnanapragasam, E.K. and Yu, C. "Analysis of BIOMOVS II Uranium Mill Tailings
Scenario 1.07 with the RESRAD Computer Code." Argonne, IL.: Argonne National Laboratory.
ANL/EAD/TM-66. 1997a.
Gnanapragasam, E.K. and Yu, C. "Application of the RESRAD Computer Code to VAMP
Scenarios." Argonne, IL.: Argonne National Laboratory. ANL/EAD/TM-70. 1997b.
Halliburton NUS Corporation. "Verification of RESRAD. A Code for Implementing Residual
Radioactive Material Guidelines, Version 5.03" Gaithersburg, MD. HNUS-ARPD-94-174.
June 1994.
Iman, R.L. and J.C. Helton. "A Comparison of Uncertainty and Sensitivity Analysis
Techniques for Computer Models." Prepared by Sandia National Laboratories, Albuquerque,
N.M., for the U.S. Nuclear Regulatory Commission, Washington, DC. NUREG/CR-3904,
SAND84-1461 RG. March 1985.
Final, February 2005 B-9 ISCORS Technical Report 2004-03
-------
Iman, R.L. and MJ. Shortencarier. "A FORTRAN 77 Program and User's Guide for the
Generation of Latin Hypercube and Random Samples for Use with Computer Models." Prepared
by Sandia National Laboratories, Albuquerque, NM, for U.S. Nuclear Regulatory Commission,
Washington, DC. NUREG/CR-3624, SAND83-2365 RG March 1984.
International Atomic Energy Agency (IAEA). "Evaluating Reliability of Predictions Made
Using Environmental Transfer Models." IAEA Report No. 100. Vienna: IAEA. 1989.
International Atomic Energy Agency (IAEA). "Validation of Models Using Chernobyl Fallout
Data from Southern Finland, Scenario S." Vienna: Second report of the VAMP Multiple
Pathways Assessment Working Group. IAEA-TECDOC-904. September 1996.
International Commission on Radiological Protection (ICRP). "Principles of Monitoring for the
Protection of the Population." ICRP Publication 43. Pergamon Press: New York, NY. 1984.
Kamboj, S., et al. "Probabilistic Dose Analysis Using Parameter Distributions Developed for
RESRAD and RESRAD-BUILD Codes." Washington, DC: U.S. Nuclear Regulatory
Commission, prepared by Argonne National Laboratory, Argonne, IL. NUREG/CR-6676,
ANL/EAD/TM-89. 2000.
Kamboj, S., C. Yu, B.M. Biwer, and T. Klett. "RESRAD-BUILD Verification." Argonne
National Laboratory, Argonne, IL. ANL/EAD/03-1. 2001.
Laniak, G.F., et al. An Overview of a Multimedia Benchmarking Analysis for Three Risk
Assessment Models: RESRAD, MMSOILS, andMEPAS." Risk Anal., 17(2):203-214. 1997.
LePoire, D., et al. "Probabilistic Modules for the RESRAD and RESRAD-BUILD Computer
Codes." Washington, DC: U.S. Nuclear Regulatory Commission, prepared by Argonne National
Laboratory, Argonne, IL. NUREG/CR-6692, ANL/EAD/TM-91. 2000.
McKay, M.D., et al. "A Comparison of Three Methods for Selecting Values of Input Variables
in the Analysis of Output from a Computer Code." Technometrics, 21:239-245. 1979.
Mills, W.B., et al. "Multimedia Benchmarking Analysis for Three Risk Assessment Models:
RESRAD, MMSOILS, andMEPAS." Risk Anal. 17(2): 187-201. 1997.
Regens, J.L., et al. "Multimedia Modeling and Risk Assessment." Washington, DC:
U.S. Department of Energy, Consortium for Environmental Risk Evaluation. May 1998.
Seitz, R.R. "Benchmarking of Computer Codes and Approaches for Modeling Exposure
Scenarios." U.S. Department of Energy; DOE/LLW-188. Prepared by Radioactive Waste
Technical Support Program, Idaho National Engineering Laboratory, Idaho Falls, ID.
August 1994.
Whelan, G., et al. "Benchmarking of the Saturated-Zone Module Associated with Three Risk
Assessment Models: RESRAD, MMSOILS, andMEPAS." Environ. Eng. Sci. 16(1):67-80.
1999a.
ISCORS Technical Report 2004-03 B-10 Final, February 2005
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Whelan, G., et al. "Benchmarking of the Vadose-Zone Module Associated with Three Risk
Assessment Models: RESRAD, MMSOILS, andMEPAS." Environ. Eng. Sci., 16(1):81-91.
1999b.
Yu, C., "RESRAD Family of Codes and Comparison with Other Codes for Decontamination and
Restoration of Nuclear Facilities," Chapter 11, pp. 207-231. Health Physics Society 1999.
Summer School Textbook, M. J. Slobodien (Ed.). Medical Physics Publishing, Madison, WI.
1999.
Tetra Tech NUS, Inc. "Verification of RESRAD-BUILD Computer Code, Version 3.1."
Prepared for Argonne National Laboratory under Contract No. 1F-00741. 2003.
Yu, C. and Gnanapragasam, E. "Testing RESRAD Predictions with Chernobyl Data."
International Symposium on the Environmental Impact of Radioactive Releases; Vienna,
Austria: IAEA-SM-339/129. May 1995.
Yu, C., et al. "Data Collection Handbook to Support Modeling the Impacts of Radioactive
Material in Soil." Argonne, IL: Argonne National Laboratory. ANL/EAIS-8. 1993a.
Yu, C., et al., "RESRAD-BUILD: A Computer Model for Analyzing the Radiological Dose
Resulting from the Remediation and Occupancy of Buildings Contaminated with Radioactive
Material." Argonne, IL.: Argonne National Laboratory. ANL/EAD/LD-3. 1994.
Yu, C., et al., "Development of Probabilistic RESRAD 6.0 and RESRAD-BUILD 3.0 Computer
Codes." Argonne, IL: Argonne National Laboratory. NUREG/CR-6697, ANL/EAD/TM-98,
2000.
Yu, C., et al., "User's Manual for RESRAD Version 6." Argonne, IL: Argonne National
Laboratory. ANL/EAD-4, 2001.
Final, February 2005 B-l 1 ISCORS Technical Report 2004-03
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Appendix C
Incinerator Control/Release Fractions
-------
-------
C.1 Introduction
Several types of incineration systems are in use for treating wastewater sludges (Brunner, 1991;
Tchobanoglous and Burton, 1991). In decreasing order of prevalence in the industry, there are:
multiple hearth furnaces, fluid bed furnaces, conveyer furnaces, and cyclone furnaces. These
operate at different temperatures, and give rise to differing amounts of volatilization of
radionuclide contaminants. Incinerators operated to manage wastewater sludges are usually
operated below the clinker temperature (the temperature at which ash fusion occurs), which is
about 1800 •¥ (980 «C) (Brunner, 1991). Formation of clinkers may interfere with the operation
of multiple hearth and fluid bed incinerators (Brunner, 1991). Consequently, an incinerator
system for sludges can be expected to produce an ash waste rather than a melt waste.
C.2 Regulatory Values for Release Fraction
EPA (1988) described potential offsite releases from an incinerator, and based the volatility
fractions for radionuclides on the recommendations of Oztunali and Roles (1984). These
recommendations are presented in Table C.I. In this table, the decontamination factor is defined
as the mass rate of contaminant in the feed divided by the mass rate of contaminant that exits the
stack and is available for transport to an offsite receptor. The release fraction is defined as the
inverse of the decontamination factor, so that it represents the fraction of the feed that exits the
stack.
These factors were estimated using various means described by Oztunali and Roles (1984). The
decontamination factor of 400 for particulates was used for all radionuclides except the ones
specifically identified in Table C.I. This decontamination factor, in turn, was derived from data
in a 1977 publication on fly ash releases from various kinds of incinerators. Oztunali and Roles
(1984) noted that even in the mid-1980s, these rates would exceed even the most minimal air
pollutant standards for particulates. For the decontamination factors for the remaining
radionuclides, Oztunali and Roles (1984) cite the earlier data compilation of Wild et al. (1981).
In turn, Wild et al. (1981) state that the value for iodine was based on data for specific fluid bed
equipment (Aerojet Company, 1975; 1979). Wild et al. (1981) also clearly acknowledge that the
values for H-3 and C-14 are purely arbitrary, owing to a lack of data.
This review of the genesis of these release fraction numbers suggests that they are either founded
on out-of-date air emissions technology or are unsupported by data. Consequently, these values
are not recommended for further use.
C.3 Assessment of Aaberg et al. (1995a)
Aaberg et al. (1995a) conducted a dose assessment of workers and the public from operation of
a generic commercial rotary kiln incinerator, used for mixed waste—co-mingled DOE waste and
commercial waste. Throughput of the facility was assumed to be 30,000 ton/yr for the base case,
with a secondary case of 150,000 ton/yr to represent a larger incinerator. Releases from the
incinerator were calculated using the CAP88-PC computer program. A number of the dispersion
and food chain parameters were taken to be CAP88-PC defaults.
Final, February 2005 C-l ISCORS Technical Report 2004-03
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As part of the assessment, the authors conducted an evaluation of contaminant partitioning. One
step in that evaluation was a literature search of partitioning values in incinerators. Values were
identified for the elements shown in Table C.2. Aaberg et al. noted that there were
inconsistencies in methods and reporting, and that none of the extant data were considered
complete or satisfactory. They do not provide specific citations for the values given in
Table C.2, nor do they identify the types of equipment and operating conditions represented by
the data. As a result, it is not clear how broad the conditions are that lead to these data. They
state that because of the inadequacies of the data sets, they investigated the thermodynamics of
the system. In this way, they developed a set of self-consistent partitioning values to be used in
their risk assessment, Table C.3. They do not describe in detail the basis for these values, but the
foundation appears to be primarily thermodynamic modeling based on free energy calculations.
The values appear to be for a high-temperature furnace, since the bottoms are described as slag
rather than ash.
Additional information on the basis for the partitioning assumptions given in Table C.3 is
provided by Aaberg et al. (1995b). This paper is described as an "extension of the technical
analysis" documented by Aaberg et al. (1995a), and it is assumed that the partitioning
methodology is similar in the two reports. Aaberg et al. (1995b) assumed thermodynamic
equilibrium to exist in the thermal processing apparatus, and considered an oxygen-rich rotary
kiln and an oxygen-deficient plasma arc furnace. Partitioning between gas and solid phases was
assumed to be a function of vapor pressure and its concentration of the contaminant. Conditions
in the incinerator were assumed to be 1000-2000 K, so the incinerator would have produced a
slag. The model was run in the computer code HSC Chemistry for Windows, assuming ideal
solution behavior. Additional details of the calculational approach apparently are given by
Burger (1995), but this report is not readily available.
Aaberg et al. (1995a) noted that the stack release values used in this study were based on generic
assumptions about air pollution control equipment used at the facility, and that the use of specific
equipment might alter these assumptions. The assumed removal efficiency of the equipment was
stated to be 5 percent for carbon, 10 percent for hydrogen, and 99.95 percent for uranium,
thorium, and other refractory metals.
C.4 Review by Liekhus et al. (1997)
Liekhus et al. (1997) conducted a review of the empirical bases for partitioning between waste
streams in high-temperature treatment equipment. The review considered both equipment for
combustion, in which excess air leads to oxidizing conditions during reaction, and for pyrolysis,
in which reactions occur in an oxygen deficient condition. Many of the applications were for
very high temperature technology, above the ash clinker temperature. That is, the bottom waste
stream in most of these applications is a melt rather than an ash. As noted above, municipal
wastewater combustion typically is kept below the clinker temperature to prevent clogging the
equipment. Consequently, many of the data cited may not be directly applicable to wastewater
combustors, and it is not clear how large the differences may be. As a result, for the purposes of
the current report, only the portions of Liekhus et al. (1997) related to ash-generating systems
that use excess air are presented in detail here.
Liekhus et al. (1997) (page C-178) noted that there has never been an explicit partitioning study
where the known amounts of metals and radionuclides are simultaneously reported in feed,
ISCORS Technical Report 2004-03 C-2 Final, February 2005
-------
bottoms ash, fly ash, and off gas. However, they cite a number of more limited sets of data that
partly describe the partitioning between feed material and ash. A summary of data is presented
in Table D-4 for the mass percent of contaminants in feed that partitioned to bottom ash. A
similar summary is presented in Table C.5 for data on fractions captured by the air pollution
control systems of the incinerators. Empty spaces in the tables indicate materials that were not
included in the original studies. These tables represent a variety of experimental conditions that
are described in detail by Liekhus et al. (1997). This variety of conditions accounts for some of
the spread in values in the table, but it also makes it difficult to derive general information from
the data.
C.5 Part 503 Metals Partitioning Information
Table C.6 lists the control efficiencies for Cleveland's sludge incinerators for the Part 503
metals, as reported by T. Lenhart of Northeast Ohio Regional Sewer District (NEORD)
(Lenhart, 2001). These efficiencies were established in formal testing as required by the
Part 503 regulations for the year 2000. NEORD believes they are representative of sludge
incinerators nationwide. The Westerly and Southerly incinerators are multiple hearth
incinerators burning dewatered sludge cake. Easterly is a fluidized bed burning skimmings.
Control efficiency is the percentage of metal in the sludge feed that does not leave the stack.
NEORD states that the control value may be indicative of either the failure to volatilize or the
removal by air pollution control devices. These values support the information from Aaberg that
describes control efficiencies of greater than 95% for most metals.
C.6 Summary
The literature on partitioning of contaminants between waste streams from an incinerator is
remarkably sparse. Few complete data sets are available for comparisons with models. The
most complete set of values for use in model inputs appears to be those reported by Aaberg et al.
(1995a) in their dose assessment of incinerator operation. These values have two drawbacks for
use in the current analysis. The basis for the calculation was a rotary kiln system operating at
higher temperatures than are typical of wastewater sludge. Also, the details of the analysis are
not well described, and must be deduced from related publications from the same research group
at about the same time. Despite these problems, these values are the only self consistent and
reasonably complete set in the literature. As a result, the values of Aaberg et al. (1995a) have
been adopted for use in assessing wastewater sludge incineration.
Final, February 2005 C-3 ISCORS Technical Report 2004-03
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Table C.1 Volatilization Fractions Recommended by Oztunali and Roles (1984)
for the Reference Pathological and Hazardous Waste Incinerators
Nuclide
H-3
C-14
Cl-36
Tc-99
Ru-103
Ru-106
1-125
1-129
All others
Decontamination Factor
1.1
1.3
100
100
100
100
100
100
400
Release Fraction
0.9
0.75
0.01
0.01
0.01
0.01
0.01
0.01
0.0025
Table C.2 Summary Range of Partitioning Values Found in the Literature by
Aaberg et al. (1995a)
Element
Cs
Sr
Zr
Co
Zn
Sb
U
Bottom Ash or Slag
60-90
45-95
60-95
70-98
30-70
10-80
65-100
Fly Ash
30-50
2-20
40-60
12-20
20-60
20-80
1-35
Stack Emissions
0.2
0.05
<1
0.5
1
1
<1
ISCORS Technical Report 2004-03
C-4
Final, February 2005
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Table C.3 Element Partitioning Assumptions Used by Aaberg et al. (1995a)
Element
H
Be
C
Na
P
S
Sc
V
Cr
Mn
Fe
Co
Ni
Zn
Ge
As
Se
Sr
Y
Zr
Nb
Tc
Ru
Ag
Sn
Sb
Fly Ash
0.1
0.1
0.02
0.1
0.13
0.65
0.05
0.1
0.35
0.35
0.45
0.34
0.4
0.49
0.5
0.5
0.8
0.05
0.05
0.05
0.05
0.5
0.59
0.2
0.02
0.43
Slag
0
0.9
0.03
0.9
0.85
0.3
0.95
0.9
0.65
0.65
0.55
0.65
0.6
0.5
0.5
0.5
0.1
0.95
0.95
0.95
0.95
0.4
0.4
0.8
0.98
0.55
Stack
0.9
0.001
0.95
0.001
0.02
0.05
0.0005
0.001
0.002
0.002
0.005
0.01
0.005
0.01
0.001
0.005
0.1
0.0001
0.0005
0.0005
0.001
0.1
0.01
0.001
0.001
0.02
Final, February 2005
C-5
ISCORS Technical Report 2004-03
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Table C.3 Element Partitioning Assumptions Used by Aaberg et al. (1995a)
(continued)
Element
Te
I
Cs
Ce
Pm
Sm
Eu
Hg
Bi
Ra
Th
U
Np
Pu
Am
Fly Ash
0.49
0.68
0.2
0.05
0.05
0.05
0.05
0.9
0.7
0.1
0.02
0.02
0.02
0.02
0.02
Slag
0.5
0.02
0.8
0.95
0.95
0.95
0.95
0.05
0.3
0.9
0.98
0.98
0.98
0.98
0.98
Stack
0.01
0.3
0.002
0.001
0.001
0.001
0.001
0.05
0.005
0.0005
0.0005
0.0005
0.0005
0.0005
0.0005
ISCORS Technical Report 2004-03
C-6
Final, February 2005
-------
Table C.4 Summary of Data Presented by Liekhus et al. (1997) for Normalized
Mass Percent of Feed Element in Bottom Ash (information adapted
from Table 4-11 of Liekhus et al.)- Values are rounded to the nearest
percent.
Element
Ag
As
Ba
Be
Bi
Ca
Cd
Cr
Cu
Hg
Mg
Mn
Ni
Pb
Sb
Se
Sr
Te
Tl
Zn
ACERC1
18-45
25-58
22-62
SWIFT2
24-93
80-99
98-99
8-34
96-99
0 for all runs
98-99
13-62
98-100
13-29
EPA IRFJ
70-97
70-98
70-72
22-91
68-91
75-99
31-92
99-100
88-129
35-99
99 for two runs
48-98
APTUS4
90-96
24-75
97-98
99-100
98-99
0-100
81-94
99-100
88-93
16-27
99-100
98-99
99-100
17-18
46-53
93-99
80-87
100 for two runs
30-98
15-37
Notes:
1 . Advanced Combustion Engineering Research Center, Bench Scale Rotary Reactor, summary of data from
7 runs.
2. Solid Waste Incineration Test Facility, Rotary Kiln System, summary of data from 9 runs.
3. US EPA Incineration Research Facility. Rotary Kiln Incinerator, summary of data for 10 runs.
4. APTUS Hazardous Waste Rotary Kiln Incinerator, Coffeyville, Kansas, summary of data from 2 runs.
Final, February 2005
C-7
ISCORS Technical Report 2004-03
-------
Table C.5 Summary of Data Presented by Liekhus et al. (1997) for Normalized
Mass Percent of Feed Element Captured by the Air Pollution Control
System (information adapted from Table 4-12 of Liekhus et al.).
Values have been rounded to the nearest percent
Element
Ag
As
Ba
Be
Bi
Ca
Cd
Cr
Cu
Hg
Mg
Mn
Ni
Pb
Sb
Se
Sr
Te
Tl
Zn
SWIFT1
7-100
1-100
1-100
74-100
1-100
100 for all runs
1-100
38-100
0-100
71-100
EPA IRE2
5-30
3-11
28-30 (2 runs)
9-78
9-32
1-15
7-97
0.07-0.2 (2 runs)
11 -3 0(2 runs)
1-65
0.3-0.6 (2 runs)
1-5 (2 runs)
APTUSJ
4-9
25-77
2-3
0-1
1-2
0-100
6-18
0-1
8-11
73-84
0-1
1-2
0-1
81-82
47-54
0-7
13-19
0 (both runs)
1-69
63-85
Notes:
1 . Solid Waste Incineration Test Facility, Rotary Kiln System, summary of data from 9 runs.
2. EPA Incineration Research Facility. Rotary Kiln Incinerator, summary of data for 8 runs.
3. APTUS Hazardous Waste Rotary Kiln Incinerator, Coffeyville, Kansas, summary of data from 2 runs.
ISCORS Technical Report 2004-03
Final, February 2005
-------
Table C.6 Average Control Efficiencies for the Easterly, Southerly, and
Westerly Incinerators
Plant
Easterly
Southerly
Westerly
Arsenic
0.9174
0.9951
0.9787
Cadmium
0.8920
0.9570
0.9401
Chromium
0.9476
0.9992
0.9994
Lead
0.9446
0.9981
0.9734
Nickel
0.9647
0.9984
0.9944
C.7 References
Aaberg, R.L., D.A. Baker, K. Rhoads, M.F. Jarvis, and W.E. Kennedy, "Radiation Dose
Assessment Methodology and Preliminary Dose Estimates to Support U.S. Department of
Energy Radiation Control Criteria for Regulated Treatment and Disposal of Hazardous Wastes
and Materials," PNL-9405, Pacific Northwest Laboratory, 1995a.
Aaberg, R.L., L.L. Burger, D.A. Baker, A. Wallo, G.A. Vasquez, and W.L. Beck, "The
Comparison of Element Partitioning in Two Types of Thermal Treatment Facilities and the
Effects on Potential Radiation Doses," PNL-SA-25207, paper presented at the 1995 International
Incineration Conference, Seattle, May 8-12, 1995b.
Aerojet Energy Conversion Company, Sacramento, California, "Fluid Bed Dryer," Topical
Report AECC-l-A, February 21, 1975.
Aerojet Energy Conversion Company, Sacramento, California, "Radioactive Waste Volume
Reduction System," Topical Report AECC-2-NP, October 15, 1979.
Brunner, C.R., "Handbook of Incineration Systems," McGraw-Hill, New York, 1991.
Burger, L.L., "A Chemical Basis for the Partitioning of Radionuclides in Incinerator Operation,"
PNL-10364, Pacific Northwest Laboratory, 1995.
EPA, "Low Level and NARM Radioactive Wastes, Draft Environmental Impact Statement for
Proposed Rules Background Information Document," EPA/520/1-87-012-1, 1988.
Liekhus, K., J. Grandy, A. Chambers, N. Soelberg, and G. Anderson, "Partitioning Planning
Studies: Preliminary Evaluation of Metal and Radionuclide Partitioning in High-Temperature
Thermal Treatment Systems," INEL/96-0450, Idaho National Engineering Laboratory, 1997.
Tchobanoglous, G., and F.L., Burton, "Wastewater Engineering," 3 ed., McGraw-Hill, New
York, 1991.
Oztunali, O.I., and G. Roles, "De Minimis Waste Impacts Analysis Methodology,"
NUREG/CR-3585, Volume 1, U.S. Nuclear Regulatory Commission, 1984.
Final, February 2005
C-9
ISCORS Technical Report 2004-03
-------
Wild, R.E., O.I. Oztunali, J.J. Clancy, CJ. Pitt, and E.D. Picazo, "Data Base for Radioactive
Waste Management: Waste Source Options Report," NUREG/CR-1759 Volume 2, U.S. Nuclear
Regulatory Commission, 1981.
Lenhart, T., "Reported Control Efficiencies for 503 metals at Westerly, Southerly, and Easterly
Incinerator Plants," email to A. Wolbarst, US EPA, January 2001.
ISCORS Technical Report 2004-03 C-10 Final, February 2005
-------
Appendix D
Conversion Between Radon Doses and
Working Level Concentrations
-------
-------
D.1 Dose- and Concentration-To-Source Ratios in Working Level
Units
This subsection describes the conversion between radon-pathway doses and Working Level
concentration levels in the onsite resident and POTW loading worker scenarios. For Rn-220 and
Rn-222 progeny, the conversion between the two dosimetric quantities committed effective dose
equivalent (CEDE) and Working Level Months (WLM) used by RESRAD and
RESRAD-BUILD is given by Equation D. 1:
= £>WLM x [Conversion Factor]
(D.I)
with the conversion factors listed in Table D. 1.
Table D.1 Radon Dosimetry Conversions Used in RESRAD and RESRAD-BUILD
Radon Isotope
Rn-220
Rn-222
Indoor or Outdoor
Indoor
Outdoor
Indoor
Outdoor
Conversion Factor
(mrem CEDE per WLM)
150
250
760
570
The conversion between dose in WLM and the concentrations of radon progeny in Working
Levels (WL) is given by the Equation D.2:
AYLM = 51.5 x time fraction
(D.2)
where time fraction is the fraction of time spent indoors or outdoors at the site. The values used
in this assessment, listed in Appendix A, have been reproduced in Table D.2, along with the
conversion factors derived from using Equation (D.I).
Table D.2 Time Fractions and WL to WLM Conversion Factors
Scenario
Onsite Resident
POTW Loading Worker
Indoor or Outdoor
Indoor
Outdoor
Indoor
Time Fraction
0.651
0.25
0.228
Conversion Factor
(WLM per WL)
33.5
12.9
11.7
Final, February 2005
D-l
ISCORS Technical Report 2004-03
-------
The conversion from dose to pCi/1 of Rn-220 or Rn-222 is not straightforward, since RESRAD
and RESRAD-BUILD calculate directly the individual concentrations of radon daughter
products (rather than using the equilibrium fraction approach). For the Onsite Resident, the
parameters that determine this conversion were not varied, so the conversion factor is a constant
6.9 x 10'3 WL per pCi Rn-222/L. For the POTW Loading Worker, the conversion factor may
range from 0.5 x 10'3 ~ 3 x 10'3 WL per pCi/1 for both Rn-220 and Rn-222. More detailed
formulas for this conversion are given in the following subsection.
D.2 Development of Publicly Owned Treatment Works
Loading Worker Radon Dose Fitting Functions
For the POTW Loading Worker subscenario, the approximate expressions for the DSR as a
function of building parameters developed in Chapter 7 were derived from parameter sensitivity
analyses of the RESRAD-BUILD code. It should be emphasized that these fitting formulas are
only valid under changes in the source dimensions, the room dimensions, the source bulk
density, the air exchange rate, and the exposure time (working hours per year). They will NOT
necessarily be valid if other baseline parameters (listed in Appendix A) are changed.
The first quantity calculated by RESRAD-BUILD is the air concentration of radon isotopes. For
a unit concentration source, following fitting formulas (Equations D.3 and E.4) were derived for
the CSR ratio, where the concentration is the activity in pCi/L of Rn-220 or Rn-222:
CSRpCi R^O/! perpci/g ^.228 * *720 x (45 + -^ rsludge ^sludge / Froom (D.3)
* '1-49 x (0.008 + -,-r1 rsludge Fsludge / Froom (D.4)
Here 'x'is the room air exchange rate in exchanges per hour, rsludge is the bulk density of the
sludge in grams per cubic cm, Fsludge is the total volume of sludge in the room in cubic meters,
and Froom is the total volume of the room in cubic meters, and ^4sludge is the surface area of the pile
of sludge in the room in square meters. The formulas are accurate to a few percent1.
The following fitting formulas (Equations D.5 and D.6) were derived converting betwen
concentrations in WL and concentrations in pCi/1 were derived from sensitivity analyses of the
baseline RESRAD-BUILD calculation:
CwLRn.220 ' -CpCiRn-220/! X 0.00417 X (1.25 hmom°'77 + '^ (D.5)
QvLRn.222 ' "CpCi Rn-222/! * 0.00625 X (2.69 hmom^ + '^ (».6)
where hmom is the height of the room in meters.
1 The motivation for the (constant + ••) ' formula is that for multiple 1st order kinetic processes (such as are
assumed for decay, air exchange, plate-out, etc.), the kinetic rates are additive. Furthermore, the equilibrium
concentration of a kinetic process will be proportional to the source injection rate and inversely proportional to
the sum of the kinetic rates.
ISCORS Technical Report 2004-03 D-2 Final, February 2005
-------
Combining Equations D.3-D.6 leads to the following Concentration-to-Source-Ratios
(Equations D.7 and D.8):
CSRWLRn.220perpCi/gT1,228 • -3.00 x (45 + V)-1 x (1.25 htoom0'77 + -^ rsludge ^sludge / Froom (D.7)
CSRWLRn.222perpCi/gRa.226 • -0.00931 x (0.008 + -^ x (2.69 hmom°'n + -fr1 rsludge Fsludge / Froom (D.8)
Furthermore, using Equation D.2 can be used to obtain Dose-to-Source in terms of WLM
(Equations D.9 and D.10). We do this using the baseline expires time (annual working hours
near the sludge) of 1,000 hours, and include the factor to correct for other exposure times texp:
!8 * * 1 /.6 x v ._, . x/ Vi.^^ "room • xy ,-jj gx
('sludge ^Sludge / ^oorn) X 0*xp / 1000 hours) <" ' >
WLMRn-222perpa/gRa-226 * * 0.0547 X (Q.008 + -^ X (2.69 T^'13 + -^ X
(kludge ^sludge/^room)X (texp/1000 hours) * ' ^
Finally, using Equation D. 1 leads to the radon dose formulas (Equations D. 11 and D. 12):
, • • 2640 x C45 + • 'V1 x d 25 h ~a77 + • 'V1 x
j Z,VJtU ^tJ xy ^l.Z,_> A
-------
-------
Appendix E
Probabilistic Percentiles for
Dose-to-Source Ratios
-------
-------
This appendix contains the probabilistic results for the Dose-to-Source Ratios (mrem/yr per
pCi/g) in sewage sludge for each scenario. Note that the scaling factors to account for multiple
years of application and waiting periods were provided in Chapter 6.
Final, February 2005 E-l ISCORS Technical Report 2004-03
-------
Table E.1 Onsite Resident DSR Percentiles (mrem/yr per pCi/g in Sewage
Sludge)
Radio-
nuclide
Ac-227
Am-241
Be-7
C-14
Ce-141
Co-57
Co-60
Cr-51
Cs-134
Cs-137
Eu-154
Fe-59
H-3
1-125
1-131
In-Ill
K-40
La- 138
Np-237
Pa-231
Pb-210
Po-210
Pu-238
Pu-239
Ra-226
Ra-228
Sm-153
Sr-89
Sr-90
Th-228
Th-229
Th-230
Th-232
Tl-201
Tl-202
U-233
U-234
U-235
U-238
Xe-131m
Zn-65
5%
3.64e-03
2.54e-04
7.44e-05
3.18e-04
5.51e-05
4.47e-04
1.78e-02
2.41e-05
1.13e-02
5.07e-03
8.49e-03
1.57e-03
1.35e-06
4.75e-05
1.13e-04
5.46e-05
1.05e-03
2.22e-03
3.23e-03
2.15e-03
1.93e-03
3.03e-04
1.76e-04
1.99e-04
1.65e-01
1.45e-02
4.62e-06
1.46e-05
9.00e-04
1.19e-02
2.54e-03
9.18e-04
1.35e-02
8.44e-06
1.57e-04
5.77e-05
5.30e-05
8.61e-04
2.13e-04
l.lle-06
3.36e-03
10%
3.97e-03
2.93e-04
7.83e-05
4.17e-04
5.78e-05
4.76e-04
1.89e-02
2.55e-05
1.20e-02
5.50e-03
9.02e-03
1.65e-03
1.56e-06
6.31e-05
1.22e-04
5.73e-05
1.12e-03
3.04e-03
4.12e-03
3.11e-03
2.50e-03
4.16e-04
2.15e-04
2.40e-04
1.67e-01
1.55e-02
4.85e-06
1.86e-05
1.25e-03
1.25e-02
2.73e-03
2.88e-03
2.06e-02
8.88e-06
1.66e-04
7.58e-05
7.09e-05
1.09e-03
2.54e-04
1.19e-06
3.82e-03
25%
4.67e-03
3.84e-04
8.70e-05
7.07e-04
6.40e-05
5.34e-04
2.13e-02
2.83e-05
1.35e-02
6.27e-03
l.OOe-02
1.84e-03
2.10e-06
9.88e-05
1.40e-04
6.34e-05
1.25e-03
6.55e-03
6.17e-03
5.37e-03
3.82e-03
7.18e-04
3.02e-04
3.39e-04
1.69e-01
1.75e-02
5.36e-06
3.21e-05
2.34e-03
1.36e-02
3.10e-03
1.28e-02
2.64e-02
9.91e-06
1.85e-04
1.17e-04
1.13e-04
1.28e-03
3.07e-04
1.34e-06
4.68e-03
50%
5.56e-03
5.26e-04
l.Ole-04
1.35e-03
7.38e-05
6.24e-04
2.48e-02
3.26e-05
1.58e-02
7.52e-03
1.17e-02
2.13e-03
3.04e-06
1.68e-04
1.67e-04
7.32e-05
1.45e-03
l.OOe-02
l.lle-02
8.79e-03
5.93e-03
1.34e-03
4.41e-04
4.92e-04
1.74e-01
2.05e-02
6.19e-06
6.41e-05
4.90e-03
1.55e-02
3.58e-03
3.63e-02
3.17e-02
1.15e-05
2.13e-04
2.06e-04
1.95e-04
1.51e-03
3.83e-04
1.55e-06
6.08e-03
75%
6.87e-03
7.22e-04
1.21e-04
3.45e-03
8.83e-05
7.50e-04
2.98e-02
3.91e-05
1.93e-02
9.36e-03
1.40e-02
2.55e-03
5.08e-06
2.86e-04
2.04e-04
8.76e-05
1.75e-03
1.27e-02
2.73e-02
1.54e-02
9.72e-03
2.59e-03
6.34e-04
7.16e-04
1.80e-01
2.46e-02
7.38e-06
1.34e-04
1.04e-02
1.80e-02
4.27e-03
5.37e-02
3.82e-02
1.38e-05
2.56e-04
3.76e-04
3.34e-04
1.82e-03
4.94e-04
1.86e-06
8.63e-03
90%
8.65e-03
1.07e-03
1.46e-04
9.83e-03
1.06e-04
9.13e-04
3.60e-02
4.69e-05
2.33e-02
1.17e-02
1.69e-02
3.07e-03
8.67e-06
4.61e-04
2.51e-04
1.05e-04
2.10e-03
1.55e-02
1.03e-01
3.06e-02
1.50e-02
4.44e-03
9.11e-04
1.02e-03
1.87e-01
3.09e-02
8.88e-06
2.66e-04
2.13e-02
2.13e-02
5.10e-03
6.01e-02
4.68e-02
1.67e-05
3.10e-04
6.24e-04
5.85e-04
2.21e-03
6.76e-04
2.25e-06
1.40e-02
95%
1.06e-02
1.43e-03
1.63e-04
2.42e-02
1.19e-04
1.03e-03
4.06e-02
5.26e-05
2.63e-02
1.35e-02
1.88e-02
3.43e-03
1.20e-05
6.09e-04
2.79e-04
1.18e-04
2.34e-03
1.78e-02
2.42e-01
4.75e-02
1.88e-02
6.13e-03
1.23e-03
1.35e-03
1.94e-01
3.55e-02
9.93e-06
4.11e-04
3.23e-02
2.36e-02
5.71e-03
6.24e-02
5.28e-02
1.88e-05
3.45e-04
1.09e-03
1.02e-03
2.53e-03
l.OOe-03
2.53e-06
2.07e-02
mean
6.25e-03
7.60e-04
1.07e-04
7.76e-03
7.85e-05
6.66e-04
2.64e-02
3.47e-05
1.71e-02
8.35e-03
1.23e-02
2.26e-03
4.31e-06
2.35e-04
1.80e-04
7.79e-05
1.54e-03
9.82e-03
6.26e-02
1.62e-02
7.73e-03
2.06e-03
5.45e-04
6.37e-04
1.76e-01
2.24e-02
6.57e-06
1.29e-04
l.Ole-02
1.62e-02
3.87e-03
3.37e-02
3.30e-02
1.23e-05
2.28e-04
5.76e-04
5.23e-04
1.73e-03
7.07e-04
1.65e-06
8.34e-03
ISCORS Technical Report 2004-03
E-2
Final, February 2005
-------
Table E.2 Recreational User DSR Percentiles (mrem/yr per pCi/g in Sewage
Sludge)
Radio-
nuclide
Ac-227
Am-241
Be-7
C-14
Ce-141
Co-57
Co-60
Cr-51
Cs-134
Cs-137
Eu-154
Fe-59
H-3
1-125
1-131
In-Ill
K-40
La- 138
Np-237
Pa-231
Pb-210
Po-210
Pu-238
Pu-239
Ra-226
Ra-228
Sm-153
Sr-89
Sr-90
Th-228
Th-229
Th-230
Th-232
Tl-201
Tl-202
U-233
U-234
U-235
U-238
Xe-131m
Zn-65
5%
1.96E-03
1.53E-04
4.42E-05
1.75E-04
3.32E-05
2.45E-04
9.61E-03
1.39E-05
5.88E-03
2.52E-03
4.89E-03
9.16E-04
3.83E-07
6.31E-06
5.47E-05
3.30E-05
6.02E-04
1.38E-03
8.15E-04
4.58E-04
2.79E-04
5.34E-05
1.07E-04
1.19E-04
8.18E-03
6.88E-03
2.75E-06
1.85E-06
5.61E-05
6.14E-03
1.39E-03
6.53E-05
5.80E-03
4.90E-06
8.90E-05
1.30E-05
1.19E-05
4.42E-04
8.50E-05
6.38E-07
1.31E-03
10%
2.05E-03
1.56E-04
4.53E-05
2.28E-04
3.33E-05
2.60E-04
1.04E-02
1.44E-05
6.02E-03
2.56E-03
5.19E-03
9.47E-04
4.72E-07
7.45E-06
5.59E-05
3.30E-05
6.24E-04
1.84E-03
9.89E-04
5.39E-04
2.98E-04
6.23E-05
1.09E-04
1.21E-04
8.19E-03
7.05E-03
2.75E-06
2.02E-06
7.04E-05
6.21E-03
1.40E-03
2.06E-04
8.35E-03
4.90E-06
9.20E-05
1.49E-05
1.32E-05
5.58E-04
1.07E-04
6.61E-07
1.65E-03
25%
2.10E-03
1.59E-04
4.58E-05
4.06E-04
3.33E-05
2.67E-04
1.07E-02
1.48E-05
6.07E-03
2.58E-03
5.33E-03
9.63E-04
6.84E-07
9.74E-06
5.72E-05
3.30E-05
6.58E-04
3.56E-03
1.10E-03
1.05E-03
3.42E-04
8.70E-05
1.11E-04
1.24E-04
8.24E-03
7.12E-03
2.75E-06
2.43E-06
1.05E-04
6.26E-03
1.42E-03
8.15E-04
1.10E-02
4.90E-06
9.42E-05
1.93E-05
1.58E-05
6.17E-04
1.15E-04
6.97E-07
1.71E-03
50%
2.15E-03
1.63E-04
4.58E-05
9.30E-04
3.33E-05
2.68E-04
1.08E-02
1.48E-05
6.11E-03
2.62E-03
5.36E-03
9.66E-04
1.13E-06
1.36E-05
5.81E-05
3.30E-05
6.83E-04
5.23E-03
1.37E-03
2.00E-03
4.21E-04
1.31E-04
1.15E-04
1.28E-04
8.31E-03
7.18E-03
2.76E-06
3.34E-06
1.84E-04
6.32E-03
1.44E-03
2.09E-03
1.19E-02
4.91E-06
9.45E-05
3.62E-05
2.10E-05
6.27E-04
1.19E-04
7.42E-07
1.77E-03
75%
2.21E-03
1.68E-04
4.58E-05
5.03E-03
3.33E-05
2.70E-04
1.08E-02
1.49E-05
6.18E-03
2.68E-03
5.36E-03
9.66E-04
2.03E-06
1.92E-05
5.94E-05
3.30E-05
7.01E-04
5.56E-03
3.48E-02
2.54E-03
5.39E-04
2.10E-04
1.20E-04
1.33E-04
8.43E-03
7.24E-03
2.76E-06
5.46E-06
3.86E-04
6.38E-03
1.46E-03
2.75E-03
1.21E-02
4.93E-06
9.46E-05
1.24E-04
3.14E-05
6.35E-04
1.26E-04
7.78E-07
1.89E-03
90%
2.29E-03
1.74E-04
4.58E-05
3.81E-02
3.33E-05
2.72E-04
1.09E-02
1.49E-05
6.30E-03
2.77E-03
5.36E-03
9.67E-04
3.40E-06
2.73E-05
6.10E-05
3.30E-05
7.12E-04
5.59E-03
2.51E-01
2.84E-03
6.83E-04
3.22E-04
1.25E-04
1.40E-04
8.58E-03
7.32E-03
2.76E-06
9.89E-06
8.41E-04
6.46E-03
1.50E-03
2.97E-03
1.23E-02
4.97E-06
9.50E-05
3.68E-04
2.39E-04
8.02E-04
2.62E-04
8.05E-07
2.13E-03
95%
2.35E-03
1.82E-04
4.58E-05
9.76E-02
3.33E-05
2.76E-04
1.10E-02
1.49E-05
6.41E-03
2.86E-03
5.36E-03
9.67E-04
4.51E-06
3.33E-05
6.23E-05
3.30E-05
7.17E-04
5.60E-03
6.07E-01
1.05E-02
8.28E-04
4.15E-04
1.29E-04
1.45E-04
8.72E-03
7.37E-03
2.77E-06
1.51E-05
1.45E-03
6.51E-03
1.52E-03
3.05E-03
1.24E-02
5.01E-06
9.54E-05
1.96E-03
1.34E-03
2.15E-03
1.23E-03
8.19E-07
2.35E-03
mean
2.17E-03
8.00E-04
4.55E-05
2.56E-02
3.33E-05
2.66E-04
1.06E-02
1.47E-05
6.12E-03
2.64E-03
5.26E-03
9.56E-04
1.64E-06
1.62E-05
5.84E-05
3.30E-05
6.75E-04
4.66E-03
1.58E-01
1.06E-02
4.72E-04
1.70E-04
1.17E-04
1.79E-04
8.53E-03
7.15E-03
2.76E-06
5.38E-06
7.68E-04
6.29E-03
1.93E-03
1.96E-03
1.13E-02
4.93E-06
9.38E-05
7.66E-04
9.51E-04
1.39E-03
1.33E-03
7.36E-07
1.82E-03
Final, February 2005
E-3
ISCORS Technical Report 2004-03
-------
Table E.3 Nearby Town DSR Percentiles (mrem/yr per pCi/g in Sewage Sludge)
(One Year of Application)
Radio-
nuclide
Ac-227
Am-241
Be-7
C-14
Ce-141
Co-57
Co-60
Cr-51
Cs-134
Cs-137
Eu-154
Fe-59
H-3
1-125
1-131
In-Ill
K-40
La-138
Np-237
Pa-231
Pb-210
Po-210
Pu-238
Pu-239
Ra-226
Ra-228
Sm-153
Sr-89
Sr-90
Th-228
Th-229
Th-230
Th-232
Tl-201
Tl-202
U-233
U-234
U-235
U-238
Xe-131m
Zn-65
5%
9.55e-06
6.62e-07
8.82e-13
2.55e-07
1.70e-ll
2.34e-ll
1.42e-09
1.99e-12
1.52e-09
2.87e-09
9.18e-10
8.27e-ll
1.37e-07
1.80e-09
2.46e-09
5.86e-12
5.78e-ll
1.83e-09
7.36e-07
2.99e-06
6.67e-08
2.00e-08
5.97e-07
6.79e-07
1.19e-04
1.72e-04
1.15e-ll
1.14e-10
3.77e-09
3.39e-04
3.22e-06
1.46e-06
1.17e-04
2.77e-12
1.32e-ll
1.95e-07
1.86e-07
1.76e-07
1.68e-07
0
4.69e-10
10%
1.17e-05
8.12e-07
1.06e-12
2.79e-07
2.01e-ll
2.94e-ll
1.83e-09
2.48e-12
1.97e-09
3.63e-09
1.19e-09
1.03e-10
1.63e-07
2.21e-09
3.03e-09
7.00e-12
7.01e-ll
2.24e-09
8.89e-07
4.50e-06
8.06e-08
2.36e-08
7.42e-07
8.29e-07
1.19e-04
1.87e-04
1.36e-ll
1.31e-10
4.92e-09
3.39e-04
3.97e-06
2.52e-06
2.00e-04
3.47e-12
1.67e-ll
2.44e-07
2.30e-07
2.22e-07
2.03e-07
0
6.16e-10
25%
1.69e-05
1.18e-06
1.50e-12
3.28e-07
2.67e-ll
4.56e-ll
2.73e-09
3.82e-12
3.05e-09
5.50e-09
1.78e-09
1.63e-10
2.05e-07
3.27e-09
4.48e-09
1.03e-ll
1.07e-10
3.27e-09
1.28e-06
8.19e-06
1.16e-07
3.12e-08
1.05e-06
1.17e-06
1.19e-04
1.93e-04
1.97e-ll
1.86e-10
7.81e-09
3.39e-04
5.60e-06
8.69e-06
2.99e-04
5.36e-12
2.59e-ll
3.67e-07
3.27e-07
3.17e-07
2.95e-07
0
1.04e-09
50%
2.45e-05
1.68e-06
2.27e-12
3.83e-07
3.96e-ll
7.33e-ll
4.21e-09
6.08e-12
5.27e-09
8.80e-09
2.72e-09
2.59e-10
2.79e-07
5.31e-09
7.27e-09
1.63e-ll
1.62e-10
5.20e-09
1.96e-06
1.59e-05
1.65e-07
4.67e-08
1.53e-06
1.67e-06
1.19e-04
1.95e-04
2.94e-ll
2.75e-10
1.23e-08
3.40e-04
8.40e-06
2.50e-05
3.35e-04
9.30e-12
4.51e-ll
5.44e-07
4.82e-07
4.65e-07
4.34e-07
0
1.70e-09
75%
3.31e-05
2.27e-06
3.29e-12
4.42e-07
5.56e-ll
1.17e-10
6.63e-09
9.49e-12
9.93e-09
1.49e-08
4.13e-09
4.16e-10
3.65e-07
8.46e-09
1.16e-08
2.41e-ll
2.42e-10
8.20e-09
2.69e-06
2.74e-05
2.22e-07
6.50e-08
2.08e-06
2.28e-06
1.19e-04
1.96e-04
4.30e-ll
3.88e-10
2.15e-08
3.40e-04
1.15e-05
3.76e-05
3.43e-04
1.66e-ll
8.07e-ll
7.90e-07
6.59e-07
6.44e-07
5.82e-07
0
2.94e-09
90%
4.96e-05
3.49e-06
4.66e-12
4.96e-07
6.59e-ll
2.01e-10
1.02e-08
1.45e-ll
1.91e-08
2.71e-08
5.94e-09
6.10e-10
4.64e-07
1.25e-08
1.72e-08
3.56e-ll
3.64e-10
1.68e-08
3.88e-06
4.16e-05
3.28e-07
8.22e-08
3.00e-06
3.40e-06
1.19e-04
1.96e-04
5.83e-ll
5.02e-10
4.05e-08
3.40e-04
1.63e-05
4.17e-05
3.47e-04
2.99e-ll
1.46e-10
1.19e-06
9.41e-07
9.77e-07
8.77e-07
0
4.57e-09
95%
5.94e-05
4.22e-06
6.43e-12
5.22e-07
7.12e-ll
2.98e-10
1.36e-08
1.80e-ll
2.84e-08
4.28e-08
7.50e-09
7.44e-10
5.32e-07
1.55e-08
2.12e-08
4.54e-ll
4.94e-10
2.69e-08
5.00e-06
5.30e-05
4.04e-07
9.68e-08
3.62e-06
3.95e-06
1.19e-04
1.96e-04
7.39e-ll
5.70e-10
5.76e-08
3.41e-04
1.92e-05
4.30e-05
3.51e-04
4.49e-ll
2.19e-10
1.50e-06
1.15e-06
1.19e-06
1.04e-06
0
5.64e-09
mean
2.74e-05
1.90e-06
2.76e-12
3.86e-07
4.15e-ll
l.OOe-10
5.53e-09
7.41e-12
8.80e-09
1.42e-08
3.24e-09
3.19e-10
2.97e-07
6.54e-09
8.96e-09
2.00e-ll
1.99e-10
9.74e-09
3.10e-06
2.02e-05
1.86e-07
5.13e-08
1.71e-06
1.88e-06
1.19e-04
1.90e-04
3.44e-ll
3.00e-10
1.99e-08
3.40e-04
9.27e-06
2.34e-05
3.02e-04
1.45e-ll
7.06e-ll
6.46e-07
5.39e-07
5.43e-07
4.84e-07
0
2.23e-09
ISCORS Technical Report 2004-03
E-4
Final, February 2005
-------
Table E.4a Landfill (Municipal Solid Waste) Neighbor (mrem/yr per pCi/g in
Sewage Sludge)
Radio-
nuclide
Ac-227
Am-241
Be-7
C-14
Ce-141
Co-57
Co-60
Cr-51
Cs-134
Cs-137
Eu-154
Fe-59
H-3
1-125
1-131
In-Ill
K-40
La-138
Np-237
Pa-231
Pb-210
Po-210
Pu-238
Pu-239
Ra-226
Ra-228
Sm-153
Sr-89
Sr-90
Th-228
Th-229
Th-230
Th-232
Tl-201
Tl-202
U-233
U-234
U-235
U-238
Xe-131m
Zn-65
5%
4.16e-13
2.01e-07
0
0
0
0
2.78e-33
0
0
2.50e-12
6.55e-25
0
0
0
0
0
7.43e-14
1.88e-36
2.87e-10
7.46e-09
3.12e-12
0
4.27e-08
4.80e-06
1.27e-03
5.33e-28
0
0
2.57e-18
0
6.31e-06
2.11e-04
1.52e-03
0
0
2.15e-07
2.55e-07
9.70e-08
4.21e-10
0
0
10%
7.69e-12
1.44e-06
0
0
0
0
3.19e-32
0
0
7.30e-12
1.04e-23
0
0
0
0
0
3.96e-13
1.07e-27
8.81e-10
2.69e-06
5.60e-12
0
5.29e-08
6.10e-06
1.32e-03
6.12e-28
0
0
1.25e-15
0
2.29e-05
3.77e-04
4.81e-03
0
0
4.19e-07
4.20e-07
1.87e-07
1.13e-09
0
0
25%
1.86e-ll
2.50e-06
0
0
0
0
9.99e-32
0
0
1.87e-ll
2.26e-23
0
0
0
0
0
4.80e-12
1.36e-14
2.68e-07
6.13e-05
1.39e-ll
0
6.80e-08
8.27e-06
1.36e-03
8.13e-28
0
0
3.62e-13
0
3.43e-05
5.64e-04
7.41e-03
0
0
1.79e-06
1.57e-06
1.03e-06
3.08e-07
0
0
50%
2.47e-ll
4.01e-06
0
0
0
0
2.67e-31
0
0
4.36e-ll
3.65e-23
0
3.30e-21
0
0
0
5.68e-ll
5.36e-09
6.69e-06
1.18e-04
3.51e-ll
0
9.48e-08
1.21e-05
1.40e-03
1.25e-27
0
0
2.07e-12
0
4.67e-05
6.01e-04
7.74e-03
0
0
5.29e-06
4.16e-06
3.12e-06
1.44e-06
0
0
75%
3.08e-ll
7.92e-06
0
0
0
0
7.45e-31
0
0
9.74e-ll
7.99e-23
0
1.91e-ll
0
0
0
4.32e-10
7.23e-08
2.56e-05
1.59e-04
8.52e-ll
0
1.74e-07
2.10e-05
1.49e-03
2.26e-27
0
0
5.84e-12
0
7.97e-05
6.55e-04
7.78e-03
0
0
8.46e-06
5.35e-06
4.95e-06
2.07e-06
0
0
90%
3.76e-ll
1.85e-05
0
1.30e-07
0
0
1.72e-30
0
0
1.88e-10
1.71e-22
0
3.54e-08
0
0
0
8.26e-07
4.88e-05
1.53e-02
2.01e-04
1.74e-10
0
3.27e-07
3.80e-05
1.67e-03
4.17e-27
0
0
1.40e-ll
0
1.15e-04
7.78e-04
7.85e-03
0
0
1.46e-05
6.28e-06
6.64e-06
2.65e-06
0
0
95%
4.77e-ll
3.72e-05
0
4.81e-05
0
0
2.95e-30
0
0
2.76e-10
2.70e-22
0
3.01e-07
0
0
0
9.19e-06
7.72e-04
1.37e-01
2.44e-04
2.54e-10
0
5.10e-07
5.58e-05
1.95e-03
5.93e-27
0
0
3.06e-ll
0
2.25e-04
8.95e-04
7.93e-03
0
0
2.46e-05
7.32e-06
8.23e-06
3.71e-06
0
0
mean
1.28e-10
1.04e-05
0
1.12e-04
0
0
1.45e-23
0
8.14e-41
3.78e-10
2.15e-17
0
6.59e-08
0
0
0
1.32e-06
1.99e-04
3.22e-02
1.68e-03
7.27e-ll
0
1.79e-07
1.88e-05
1.47e-03
1.97e-27
0
0
1.08e-08
0
7.34e-05
6.04e-04
7.01e-03
0
0
1.46e-04
4.52e-05
1.38e-04
3.70e-05
0
0
Final, February 2005
E-5
ISCORS Technical Report 2004-03
-------
Table E.4b Landfill (Surface Impoundment) Neighbor (mrem/yr per pCi/g in
Sewage Sludge)
Radio-
nuclide
Ac-227
Am-241
Be-7
C-14
Ce-141
Co-57
Co-60
Cr-51
Cs-134
Cs-137
Eu-154
Fe-59
H-3
1-125
1-131
In-Ill
K-40
La- 138
Np-237
Pa-231
Pb-210
Po-210
Pu-238
Pu-239
Ra-226
Ra-228
Sm-153
Sr-89
Sr-90
Th-228
Th-229
Th-230
Th-232
Tl-201
Tl-202
U-233
U-234
U-235
U-238
Xe-131m
Zn-65
5%
4.63e-ll
2.09e-05
0
1.45e-15
0
0
4.15e-31
0
0
2.20e-10
1.48e-22
0
2.03e-35
0
0
0
2.01e-ll
7.26e-36
4.26e-08
2.06e-06
1.97e-10
0
2.20e-06
1.90e-04
6.60e-02
2.67e-26
0
0
2.72e-16
0
3.73e-04
1.22e-02
1.32e-01
0
0
8.89e-06
1.43e-05
1.50e-06
3.77e-09
0
0
10%
4.77e-10
7.07e-05
0
8.87e-13
0
0
2.40e-30
0
0
4.11e-10
8.77e-22
0
1.51e-32
0
0
0
8.30e-ll
9.45e-24
1.07e-07
2.01e-04
3.18e-10
0
2.59e-06
2.45e-04
6.80e-02
3.08e-26
0
0
3.51e-13
0
9.62e-04
2.28e-02
2.92e-01
0
0
1.92e-05
2.37e-05
5.77e-06
9.81e-08
0
0
25%
9.67e-10
1.04e-04
0
8.83e-09
0
0
6.15e-30
0
0
1.04e-09
1.59e-21
0
2.14e-26
0
0
0
7.43e-10
1.06e-ll
2.91e-05
2.89e-03
7.35e-10
0
3.32e-06
3.31e-04
6.98e-02
4.14e-26
0
0
3.39e-ll
0
1.41e-03
3.00e-02
3.87e-01
0
0
9.35e-05
8.87e-05
4.76e-05
1.71e-05
0
0
50%
1.24e-09
1.58e-04
0
4.54e-08
0
0
1.60e-29
0
0
2.33e-09
2.50e-21
0
1.63e-18
0
0
0
4.83e-09
5.33e-07
3.42e-04
4.88e-03
1.82e-09
0
4.80e-06
4.72e-04
7.12e-02
6.74e-26
0
0
1.25e-10
0
1.91e-03
3.15e-02
3.98e-01
0
0
2.20e-04
2.05e-04
1.29e-04
5.87e-05
0
0
75%
1.57e-09
3.11e-04
0
2.41e-07
0
0
3.78e-29
0
0
5.26e-09
4.52e-21
0
3.04e-09
0
0
0
2.32e-08
4.63e-06
1.22e-03
6.36e-03
4.31e-09
0
8.55e-06
8.47e-04
7.49e-02
1.18e-25
0
0
3.29e-10
0
3.07e-03
3.41e-02
4.00e-01
0
0
3.36e-04
2.53e-04
2.01e-04
8.27e-05
0
0
90%
1.95e-09
7.95e-04
0
2.84e-05
0
0
9.31e-29
0
0
l.Ole-08
9.27e-21
0
1.89e-06
0
0
0
3.55e-05
3.25e-03
1.13e+00
8.38e-03
9.18e-09
0
1.65e-05
1.62e-03
8.18e-02
2.12e-25
0
0
8.27e-10
0
5.88e-03
3.87e-02
4.03e-01
0
0
6.07e-04
3.00e-04
2.67e-04
1.06e-04
0
0
95%
2.48e-09
1.90e-03
0
6.02e-03
0
0
1.68e-28
0
0
1.39e-08
1.42e-20
0
1.66e-05
0
0
0
4.26e-04
4.45e-02
1.18e+01
1.04e-02
1.52e-08
0
2.52e-06
2.37e-03
8.88e-02
3.24e-25
0
0
1.58e-09
0
9.45e-03
4.32e-02
4.06e-01
0
0
9.33e-04
3.41e-04
3.36e-04
1.38e-04
0
0
mean
3.75e-08
4.88e-04
0
8.31e-03
0
0
9.93e-25
0
0
4.24e-09
4.40e-21
0
3.39e-06
0
0
0
6.08e-05
1.09e-02
2.51e+00
3.80e-02
3.96e-09
0
8.45e-06
7.82e-04
7.38e-02
4.25e-21
0
0
2.06e-05
0
3.12e-03
3.13e-02
3.65e-01
0
0
4.33e-03
5.00e-04
5.32e-03
2.02e-03
0
0
ISCORS Technical Report 2004-03
E-6
Final, February 2005
-------
Table E.5 Incinerator Neighbor (mrem/yr per pCi/g in Sewage Sludge)
:ladio-
luclide
Ac-227
A.m-241
Be-7
C-14
Ce-141
Co-57
Co-60
Cr-51
Cs-134
Cs-137
Eu-154
Fe-59
H-3
[-125
[-131
In-Ill
K-40
La-138
Np-237
Pa-231
Pb-210
Po-210
Pu-238
Pu-239
Ra-226
Ra-228
Sm-153
Sr-89
Sr-90
Th-228
Th-229
Th-230
Th-232
ri-201
11-202
LJ-233
LJ-234
LJ-235
LJ-238
Xe-131m
Z.n-65
5%
5.79e+00
3.94e-01
3.61e-07
1.95e-07
1.75e-06
1.90e-05
2.11e-03
1.98e-07
1.46e-03
2.74e-03
1.67e-03
8.17e-05
1.54e-06
1.16e-02
2.17e-03
4.78e-08
1.03e-04
1.97e-03
4.92e-01
1.17e+00
2.46e-02
6.60e-03
3.48e-01
3.82e-01
2.97e-02
1.19e-02
5.34e-08
1.75e-05
4.29e-03
2.56e-01
1.89e+00
2.85e-01
1.46e+00
1.99e-08
5.12e-07
1.19e-01
1.16e-01
1.09e-01
1.04e-01
0
3.06e-04
10%
6.35e+00
4.32e-01
3.88e-07
2.14e-07
1.86e-06
2.11e-05
2.38e-03
2.24e-07
1.66e-03
3.26e-03
1.80e-03
9.29e-05
1.70e-06
1.37e-02
2.56e-03
5.19e-08
1.25e-04
2.23e-03
5.38e-01
1.26e+00
2.67e-02
7.15e-03
3.79e-01
4.17e-01
3.21e-02
1.27e-02
5.81e-08
1.91e-05
5.13e-03
2.81e-01
2.08e+00
3.13e-01
1.60e+00
2.32e-08
5.93e-07
1.30e-01
1.27e-01
1.19e-01
1.14e-01
0
3.66e-04
25%
7.46e+00
5.06e-01
4.57e-07
2.51e-07
2.07e-06
2.57e-05
2.91e-03
2.84e-07
2.16e-03
4.15e-03
2.12e-03
1.20e-04
1.99e-06
2.00e-02
3.73e-03
6.12e-08
1.65e-04
2.73e-03
6.28e-01
1.48e+00
2.98e-02
8.16e-03
4.44e-01
4.89e-01
3.70e-02
1.42e-02
6.65e-08
2.20e-05
7.19e-03
3.30e-01
2.44e+00
3.68e-01
1.87e+00
3.21e-08
7.73e-07
1.52e-01
1.49e-01
1.39e-01
1.33e-01
0
5.30e-04
50%
8.71e+00
5.90e-01
5.63e-07
2.92e-07
2.33e-06
3.38e-05
3.82e-03
3.82e-07
2.96e-03
5.57e-03
2.61e-03
1.60e-04
2.32e-06
2.99e-02
5.57e-03
7.79e-08
2.27e-04
3.84e-03
7.31e-01
1.73e+00
3.39e-02
9.58e-03
5.18e-01
5.70e-01
4.44e-02
1.63e-02
7.97e-08
2.70e-05
l.lle-02
3.85e-01
2.85e+00
4.30e-01
2.18e+00
5.12e-08
1.15e-06
1.78e-01
1.74e-01
1.63e-01
1.56e-01
0
8.34e-04
75%
l.OOe+01
6.79e-01
7.04e-07
3.38e-07
2.59e-06
4.94e-05
4.85e-03
5.33e-07
4.20e-03
7.81e-03
3.28e-03
2.26e-04
2.69e-06
4.28e-02
7.97e-03
1.12e-07
3.17e-04
6.73e-03
8.45e-01
1.99e+00
3.86e-02
1.13e-02
5.99e-01
6.58e-01
5.35e-02
1.88e-02
1.09e-07
3.32e-05
1.79e-02
4.44e-01
3.29e+00
4.96e-01
2.52e+00
9.34e-08
1.98e-06
2.06e-01
2.01e-01
1.88e-01
1.80e-01
0
1.28e-03
90%
1.12e+01
7.61e-01
9.04e-07
3.79e-07
2.86e-06
7.35e-05
6.50e-03
7.21e-07
5.56e-03
l.lle-02
3.92e-03
2.96e-04
3.01e-06
5.86e-02
1.09e-02
1.78e-07
4.16e-04
9.14e-03
9.40e-01
2.23e+00
4.31e-02
1.41e-02
6.70e-01
7.36e-01
7.03e-02
2.21e-02
1.56e-07
4.12e-05
2.91e-02
4.97e-01
3.68e+00
5.55e-01
2.82e+00
1.61e-07
3.36e-06
2.30e-01
2.25e-01
2.10e-01
2.01e-01
0
1.82e-03
95%
1.18e+01
7.99e-01
1.09e-06
3.99e-07
3.02e-06
1.02e-04
7.97e-03
8.78e-07
6.69e-03
1.43e-02
4.34e-03
3.54e-04
3.17e-06
6.99e-02
1.31e-02
2.42e-07
4.81e-04
1.06e-02
9.93e-01
2.35e+00
4.74e-02
1.64e-02
7.04e-01
7.74e-01
8.80e-02
2.53e-02
2.03e-07
4.70e-05
3.86e-02
5.23e-01
3.87e+00
5.85e-01
2.97e+00
2.31e-07
4.74e-06
2.43e-01
2.37e-01
2.22e-01
2.12e-01
0
2.28e-03
mean
8.76e+00
5.94e-01
6.15e-07
2.95e-07
2.35e-06
4.38e-05
4.29e-03
4.37e-07
3.40e-03
6.68e-03
2.74e-03
1.82e-04
2.34e-06
3.36e-02
6.26e-03
1.04e-07
2.51e-04
4.94e-03
7.37e-01
1.74e+00
3.47e-02
1.02e-02
5.22e-01
5.74e-01
4.90e-02
1.72e-02
9.83e-08
2.88e-05
1.50e-02
3.87e-01
2.86e+00
4.32e-01
2.20e+00
8.11e-08
1.75e-06
1.79e-01
1.75e-01
1.64e-01
1.57e-01
0
l.Ole-03
Final, February 2005
E-7
ISCORS Technical Report 2004-03
-------
Table E.6 Sludge Application Worker (mrem/yr per pCi/g in Sewage Sludge)
Radio-
nuclide
Ac-227
Am-241
Be-7
C-14
Ce-141
Co-57
Co-60
Cr-51
Cs-134
Cs-137
Eu-154
Fe-59
H-3
1-125
1-131
In-Ill
K-40
La-138
Np-237
Pa-231
Pb-210
Po-210
Pu-238
Pu-239
Ra-226
Ra-228
Sm-153
Sr-89
Sr-90
Th-228
Th-229
Th-230
Th-232
Tl-201
Tl-202
U-233
U-234
U-235
U-238
Xe-131m
Zn-65
5%
1.71e-03
5.08e-05
3.79e-05
3.66e-08
2.59e-05
1.81e-04
8.55e-03
1.16e-05
5.04e-03
2.12e-03
4.13e-03
8.19e-04
6.46e-08
l.lle-07
4.47e-05
2.73e-05
5.27e-04
8.98e-04
3.88e-04
3.27e-04
4.46e-06
3.40e-07
2.98e-05
3.27e-05
7.37e-03
6.15e-03
1.78e-06
9.58e-07
1.02e-05
5.68e-03
1.20e-03
l.OOe-04
4.79e-03
3.27e-06
7.30e-05
1.07e-05
9.31e-06
2.94e-04
7.18e-05
3.37e-07
9.59e-04
10%
1.90e-03
6.04e-05
3.93e-05
4.26e-08
2.60e-05
1.94e-04
9.28e-03
1.22e-05
5.22e-03
2.19e-03
4.54e-03
8.57e-04
7.67e-08
1.32e-07
4.61e-05
2.73e-05
5.50e-04
1.23e-03
5.49e-04
4.86e-04
4.97e-06
4.46e-07
3.91e-05
4.24e-05
7.38e-03
6.37e-03
1.78e-06
1.04e-06
1.25e-05
5.77e-03
1.25e-03
1.82e-04
7.32e-03
3.28e-06
7.71e-05
1.51e-05
1.23e-05
4.19e-04
8.93e-05
3.48e-07
1.33e-03
25%
2.35e-03
8.89e-05
3.99e-05
5.66e-08
2.60e-05
2.02e-04
9.74e-03
1.26e-05
5.32e-03
2.23e-03
4.70e-03
8.76e-04
1.03e-07
1.69e-07
4.78e-05
2.73e-05
5.83e-04
2.64e-03
7.41e-04
1.02e-03
6.38e-06
7.30e-07
6.48e-05
7.10e-05
7.38e-03
6.47e-03
1.78e-06
1.12e-06
1.50e-05
5.84e-03
1.39e-03
5.47e-04
l.Ole-02
3.28e-06
7.98e-05
2.65e-05
2.06e-05
4.99e-04
9.95e-05
3.70e-07
1.50e-03
50%
3.17e-03
1.43e-04
3.99e-05
8.05e-08
2.60e-05
2.04e-04
9.85e-03
1.27e-05
5.35e-03
2.25e-03
4.73e-03
8.80e-04
1.49e-07
1.95e-07
4.87e-05
2.73e-05
6.11e-04
4.56e-03
8.18e-04
2.06e-03
8.95e-06
1.24e-06
l.lle-04
1.25e-04
7.39e-03
6.53e-03
1.78e-06
1.14e-06
1.58e-05
5.91e-03
1.66e-03
1.58e-03
1.10e-02
3.28e-06
8.03e-05
5.22e-05
3.64e-05
5.17e-04
1.14e-04
3.93e-07
1.52e-03
75%
4.40e-03
2.32e-04
3.99e-05
1.13e-07
2.60e-05
2.05e-04
9.87e-03
1.27e-05
5.35e-03
2.25e-03
4.73e-03
8.81e-04
2.13e-07
2.02e-07
4.89e-05
2.73e-05
6.32e-04
5.01e-03
9.25e-04
3.40e-03
1.31e-05
2.08e-06
1.88e-04
2.09e-04
7.40e-03
6.60e-03
1.78e-06
1.15e-06
1.61e-05
6.01e-03
2.06e-03
2.31e-03
1.15e-02
3.28e-06
8.03e-05
9.92e-05
6.00e-05
5.43e-04
1.36e-04
4.12e-07
1.52e-03
90%
6.18e-03
3.48e-04
4.00e-05
1.47e-07
2.60e-05
2.05e-04
9.87e-03
1.27e-05
5.35e-03
2.25e-03
4.73e-03
8.81e-04
2.85e-07
2.04e-07
4.90e-05
2.73e-05
6.45e-04
5.07e-03
1.06e-03
5.06e-03
1.89e-05
3.22e-06
2.91e-04
3.24e-04
7.41e-03
6.68e-03
1.78e-06
1.15e-06
1.64e-05
6.13e-03
2.68e-03
2.56e-03
1.20e-02
3.28e-06
8.03e-05
1.58e-04
9.50e-05
5.79e-04
1.67e-04
4.28e-07
1.52e-03
95%
7.62e-03
4.42e-04
4.00e-05
1.71e-07
2.60e-05
2.05e-04
9.87e-03
1.27e-05
5.35e-03
2.25e-03
4.73e-03
8.81e-04
3.36e-07
2.05e-07
4.90e-05
2.73e-05
6.51e-04
5.08e-03
1.17e-03
6.41e-03
2.34e-05
4.16e-06
3.75e-04
4.16e-04
7.41e-03
6.74e-03
1.78e-06
1.15e-06
1.67e-05
6.23e-03
3.15e-03
2.63e-03
1.25e-02
3.28e-06
8.03e-05
1.99e-04
1.23e-04
6.08e-04
1.94e-04
4.35e-07
1.52e-03
mean
3.68e-03
1.80e-04
3.95e-05
8.93e-08
2.60e-05
2.00e-04
9.61e-03
1.25e-05
5.29e-03
2.22e-03
4.62e-03
8.69e-04
1.68e-07
1.80e-07
4.80e-05
2.73e-05
6.03e-04
3.78e-03
8.20e-04
2.50e-03
1.08e-05
1.62e-06
1.46e-04
1.59e-04
7.39e-03
6.49e-03
1.78e-06
l.lle-06
1.51e-05
5.90e-03
1.84e-03
1.46e-03
1.03e-02
3.28e-06
7.92e-05
7.34e-05
4.70e-05
5.05e-04
1.21e-04
3.90e-07
1.45e-03
ISCORS Technical Report 2004-03
Eo
-O
Final, February 2005
-------
Table E.7a POTW Worker: Biosolids Loading (mrem/yr per pCi/g in Sewage
Sludge)
Radio-
nuclide
Ac-227
Am-241
Be-7
C-14
Ce-141
Co-57
Co-60
Cr-51
Cs-134
Cs-137
Eu-154
Fe-59
H-3
1-125
1-131
In-Ill
K-40
La-138
Np-237
Pa-231
Pb-210
Po-210
Pu-238
Pu-239
Ra-228
Sm-153
Sr-89
Sr-90
Th-229
Th-230
Th-232
Tl-201
Tl-202
U-233
U-234
U-235
U-238
Xe-131m
Zn-65
5%
8.50E-02
1.58E-03
1.23E-02
4.39E-07
1.25E-02
1.92E-02
7.00E-01
7.40E-03
4.07E-01
1.46E-01
3.32E-01
3.31E-01
7.05E-05
6.00E-04
9.20E-02
8.05E-02
4.53E-02
3.45E-01
1.36E-04
8.40E-03
2.09E-04
4.39E-06
9.60E-05
9.45E-05
2.59E-01
5.80E-03
3.93E-04
9.85E-04
6.60E-02
1.18E-04
3.81E-04
1.01E-02
1.05E-01
8.55E-05
4.70E-05
3.02E-02
5.75E-03
8.75E-04
1.60E-01
10%
8.70E-02
1.72E-03
1.23E-02
4.40E-07
1.25E-02
1.92E-02
7.00E-01
7.40E-03
4.07E-01
1.46E-01
3.32E-01
3.31E-01
1.01E-04
6.00E-04
9.20E-02
8.05E-02
4.53E-02
3.45E-01
2.98E-04
8.75E-03
2.16E-04
6.40E-06
2.07E-04
2.17E-04
2.59E-01
5.80E-03
3.93E-04
9.85E-04
6.70E-02
2.06E-04
8.75E-04
1.01E-02
1.05E-01
1.24E-04
8.50E-05
3.02E-02
5.75E-03
8.75E-04
1.60E-01
25%
9.45E-02
2.30E-03
1.23E-02
4.42E-07
1.25E-02
1.92E-02
7.00E-01
7.40E-03
4.07E-01
1.46E-01
3.32E-01
3.31E-01
1.64E-04
6.00E-04
9.20E-02
8.05E-02
4.53E-02
3.45E-01
l.OOE-03
1.02E-02
2.41E-04
1.62E-05
6.55E-04
7.55E-04
2.59E-01
5.80E-03
3.93E-04
9.90E-04
6.95E-02
5.85E-04
2.95E-03
1.01E-02
1.05E-01
2.94E-04
2.39E-04
3.04E-02
5.90E-03
8.75E-04
1.60E-01
50%
1.17E-01
3.85E-03
1.23E-02
4.50E-07
1.25E-02
1.92E-02
7.00E-01
7.40E-03
4.07E-01
1.46E-01
3.32E-01
3.31E-01
3.06E-04
6.00E-04
9.20E-02
8.05E-02
4.53E-02
3.45E-01
2.83E-03
1.51E-02
3.23E-04
4.76E-05
2.17E-03
2.25E-03
2.59E-01
5.80E-03
3.94E-04
9.95E-04
7.75E-02
1.84E-03
8.80E-03
1.01E-02
1.05E-01
7.60E-04
7.75E-04
3.08E-02
6.35E-03
8.75E-04
1.60E-01
75%
1.77E-01
7.85E-03
1.23E-02
4.72E-07
1.25E-02
1.92E-02
7.00E-01
7.40E-03
4.07E-01
1.46E-01
3.32E-01
3.31E-01
5.85E-04
6.00E-04
9.20E-02
8.05E-02
4.53E-02
3.45E-01
7.50E-03
2.74E-02
5.25E-04
1.23E-04
5.75E-03
6.20E-03
2.59E-01
5.80E-03
3.94E-04
1.01E-03
9.75E-02
4.97E-03
2.56E-02
1.01E-02
1.05E-01
2.00E-03
2.01E-03
3.19E-02
7.55E-03
8.75E-04
1.60E-01
90%
3.07E-01
1.74E-02
1.23E-02
5.10E-07
1.25E-02
1.92E-02
7.00E-01
7.40E-03
4.07E-01
1.46E-01
3.32E-01
3.31E-01
9.25E-04
6.00E-04
9.20E-02
8.05E-02
4.53E-02
3.45E-01
1.77E-02
4.90E-02
9.50E-04
2.70E-04
1.19E-02
1.56E-02
2.59E-01
5.80E-03
3.94E-04
1.03E-03
1.39E-01
1.11E-02
5.60E-02
1.01E-02
1.05E-01
4.97E-03
4.17E-03
3.42E-02
9.55E-03
8.75E-04
1.60E-01
95%
4.05E-01
2.35E-02
1.23E-02
5.60E-07
1.25E-02
1.92E-02
7.00E-01
7.40E-03
4.07E-01
1.46E-01
3.32E-01
3.31E-01
1.33E-03
6.00E-04
9.20E-02
8.05E-02
4.53E-02
3.46E-01
2.89E-02
8.05E-02
1.33E-03
4.35E-04
1.80E-02
2.38E-02
2.59E-01
5.80E-03
3.95E-04
1.05E-03
1.74E-01
1.68E-02
8.35E-02
1.01E-02
1.05E-01
7.55E-03
6.15E-03
3.68E-02
1.13E-02
8.75E-04
1.60E-01
mean
1.74E-01
7.75E-03
1.23E-02
4.68E-07
1.25E-02
1.92E-02
7.00E-01
7.40E-03
4.07E-01
1.46E-01
3.32E-01
3.31E-01
4.62E-04
6.00E-04
9.20E-02
8.05E-02
4.53E-02
3.45E-01
7.50E-03
2.57E-02
5.00E-04
1.11E-04
5.15E-03
5.95E-03
2.59E-01
5.80E-03
3.94E-04
1.01E-03
9.50E-02
4.49E-03
2.21E-02
1.01E-02
1.05E-01
1.93E-03
1.80E-03
3.19E-02
7.25E-03
8.75E-04
1.60E-01
Final, February 2005
E-9
ISCORS Technical Report 2004-03
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Table E.7b POTW Worker: Biosolids Loading for Ra-226 and Combinations of Air
Exchange Rate and Building Height
air
exchange
rate
(h1)
1.5
O
5
room
height
(m)
2
4
6
2
4
6
2
4
6
5%
1.5
1.2
1.0
0.92
0.76
0.68
0.70
0.61
0.57
10%
1.7
1.3
1.1
0.98
0.78
0.69
0.72
0.62
0.58
25%
2.2
1.5
1.2
1.1
0.82
0.72
0.76
0.63
0.58
50%
2.6
1.6
1.2
1.2
0.85
0.73
0.79
0.64
0.59
75%
2.7
1.6
1.2
1.2
0.85
0.73
0.79
0.64
0.59
90%
2.7
1.6
1.2
1.2
0.85
0.73
0.79
0.64
0.59
95%
2.7
1.6
1.2
1.2
0.85
0.73
0.79
0.64
0.59
mean
2.4
1.5
1.2
1.1
0.83
0.72
0.77
0.63
0.59
Table E.7c POTW Worker: Biosolids Loading for Th-228 and Combinations of Air
Exchange Rate and Building Height
air
exchange
rate
(h1)
1.5
O
5
room
height
(m)
2
4
6
2
4
6
2
4
6
5%
6.4
4.9
4.0
4.8
3.4
2.6
3.7
2.4
1.9
10%
7.8
5.6
4.5
5.6
3.7
2.8
4.0
2.6
1.9
25%
12
7.6
5.5
7.5
4.3
3.1
4.9
2.8
2.1
50%
17
9.1
6.3
8.9
4.8
3.3
5.5
3.0
2.1
75%
18
9.4
6.4
9.2
4.8
3.4
5.6
3.0
2.2
90%
18
9.4
6.4
9.3
4.9
3.4
5.6
3.0
2.2
95%
18
9.4
6.4
9.3
4.9
3.4
5.6
3.0
2.2
mean
15
8.3
5.9
8.2
4.5
3.2
5.2
2.9
2.1
ISCORS Technical Report 2004-03
E-10
Final, February 2005
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Appendix F
Responses to Peer Review Comments
on ISCORS Dose Modeling Document
-------
-------
F.1 Overview of Peer/General Review Process
In this appendix, ISCORS responds to comments solicited from a group of expert peer reviewers
and from members of the public with regard to the modeling methodology employed and to the
technical aspects of the methodology and assumptions underlying the dose assessment.1
Solicitation for Comments from Peer Reviewers and Others
The draft final version of this report was reviewed in depth by a committee of peer reviewers
selected by ISCORS, and it also was reviewed by interested organizations and members of the
general public. The individuals who were asked to serve as members of the new peer group are
all professional experts in sludge management and/or environment pathway modeling, and are
representatives of the Pacific Northwest National Laboratory, Weston Solutions, Black & Veatch
Engineering Company, the Madison and Cincinnati METROs, and the States of Colorado, and
Pennsylvania. The reviewers met in a conference call, and although they were encouraged to
communicate with one another and with ISCORS, they submitted independent reports. Six of
the eight submitted written comments. The members of the invited committee of peer reviewers
include the following:
1. Pacific NW National Lab - Gene Whelan, Dennis Strenge, and James Droppo (PNNL)
2. State of Colorado, Department of Public Health and the Environment - Phil Egidi (CO)
3. State of Pennsylvania, Department of Environmental Protection - Jeff Whitehead (PA)
4. State of Washington, Department of Health - Debra McBaugh and Mike Brennan (WA)
5. Weston Solutions - Mark Miller and Marc Garcia (Weston)
6. Madison METRO - David Taylor (Madison)
7. Black & Veatch Engrs - Dick Kuchenrither (no written comments)
8. Cincinnati METRO - Pat Karney, Mike Heitz, and Beverly Mead (no written comments)
The peer reviewers were asked to provide general technical review and to respond to three
categories of specific questions:
1. Are the dose modeling scenarios reasonable? Does the document adequately explain
them? Are the scenarios sufficiently representative of the major exposure situations?
2. Is the dose modeling approach scientifically reasonable and appropriately documented
and characterized? Are the selection of model parameters and distributions and the
approach for characterizing uncertainty reasonable?
1 An earlier version of this report was reviewed during 2000-2001 by EPA's Science Advisory Board (SAB).
Their response was generally favorable, but they offered numerous suggestions and recommendations, virtually
all of which were incorporated into this report. The work has evolved considerably since that time, and it was
felt that a new review by an independent peer group would be both appropriate and beneficial to the project.
Final, February 2005 F-l ISCORS Technical Report 2004-03
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3. Are the overall conclusions consistent with the results of the dose modeling and
appropriately characterized?
In addition, the November 26, 2003, issue of the Federal Register (Vol. 68, No. 228:
66503-66504) announced the availability of'the Final Survey Report., the Draft Final Dose
Modeling Report, and the Draft Final POTW Recommendations Document., and ISCORS
requested comment on the two draft final documents. In addition, ISCORS directly informed the
relevant Federal agencies and the directors of all State radiation control programs, the
Conference of Radiation Control Program Directors (CRCPD), and the Organization of
Agreement States (OAS). A total of nine sets of comments were received, apart from those of
the peer reviewers, from the following:
1. Association of Metropolitan Sewerage Agencies (AMSA)
2. American Water Works Association (AWWA)
3. Council on Radionuclides and Radiopharmaceuticals, Inc. (CORAR)
4. State of Illinois Dept. of Environmental Protection
5. State of New Jersey Dept. of Environmental Protection
6. UniTech Corp.
7. U. S. DOE Richland Operations Office (Hanford, Washington)
8. U.S. NRC Division of Waste Management and Environmental Protection
9. Water Remediation Technology, LLC (WRT)
The comments from AMSA, AWWA, and CORAR dealt almost entirely with the draft final
recommendations document. The few comments that addressed modeling are discussed herein.
Upon request by EPA, UniTech clarified in a letter dated April 15, 2004, several of its earlier
comments. WRT submitted comments and a report they commissioned: Total Effective Dose
Equivalent (TEDE) Calculations for Radium-Bearing Sewage Sludge Under Various Exposure
Scenarios. Upon request by EPA, WRT submitted an e-mail on April 20, 2004, intended to
highlight the major, relevant points in their report.
The comments from the peer reviewers were positive and supportive, as were those from all but
one of the other commenters. They all offered a number of specific constructive suggestions for
changes, and, after considering them carefully, ISCORS separated them into categories to
facilitate response. ISCORS agreed with a number of the comments and made appropriate
revisions. ISCORS disagreed with other comments and the explanations are presented below.
ISCORS considered some of the recommendations to be useful but not essential to the analysis
and, in some cases, beyond the scope of the ISCORS effort: implementing these
recommendations would require additional resources, and these recommendations are included
as possible future activities.
ISCORS Technical Report 2004-03 F-2 Final, February 2005
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F.2 Positive Comments
The following general positive comments were provided by the peer reviewers that required no
response:
•• The document uses generally accepted models and risk assessment tools.
•• The document is comprehensive/thorough.
•• The answer to all three questions posed to the peer reviewers is "Yes."
•• The process was sound, scientifically reasonable, and complete.
•• The report covers virtually every reasonably anticipated scenario and operational assumptions
for screening.
•• The procedures were implemented in a systematic, scientific manner.
•• The modeling approach is scientifically reasonable.
•• The parameters/distributions and approach for characterizing uncertainty appear reasonable
and conservative.
•• ISCORS adequately bounds the issue—the level of conservatism was generally appropriate.
•• The scenarios are reasonable for screening.
•• The report represents most major exposure situations.
•• The commenters agree that NORM and TENORM are likely to be the major potential sources
for elevated sources of radiation in sewage sludge—this was a surprising and irrefutable
finding of the study.
•• ISCORS should publicize the results of the dose modeling effort via HPS and ANS meetings,
Health Physics Journal, the Internet, and other venues.
F.3 Comments Requiring Response
The comments from peer reviewers that required a response are discussed below.
F.3.1 Documentation/Presentation
•• Comment: The document needs a more detailed explanation of models (e.g., how modeling
was done).
Response: ISCORS provided an appendix on RESRAD and included a reference
(i.e., a URL) to the online RESRAD Users Manual.
•• Comment: The document should provide a more complete description of the parameters and
distributions (rather than just referencing other reports). There is too much reliance on
references to other reports; ISCORS should supply the information.
Response: ISCORS made no change to the document because NRC NUREG/CR-6697, the
EPA Exposure Factors Handbook (EPA/600-P-95-002Fa), and other sources listed as
references provide comprehensive documentation and are readily available.
Final, February 2005 F-3 ISCORS Technical Report 2004-03
-------
•• Comment: The document should include a list of appropriate Federal and State agency
contacts, and access to an updated list should be available via the ISCORS Web site.
Response: ISCORS provides such a list in the final recommendations document.
•• Comment: ISCORS should develop an executive summary for the dose modeling document.
Response: ISCORS included an executive summary in the final document.
•• Comment: ISCORS should upgrade the presentation of results by crafting and presenting
output in visual/graphical format (PNNL).
Response: ISCORS modified some tables to improve their appearance and readability. Due
to resource constraints, no significant visual/graphical format enhancements were undertaken.
F.3.2 Scenarios/Parameters
F.3.2.1 Conservativeness of Parameters
•• Comment: Some assumptions are overly conservative (or must be justified) (e.g., 100% of
milk and meat, building height, air exchange rate—2 times per hour, sewage sludge density)
for most POTWs.
Response: ISCORS reexamined all potentially sensitive parameters and altered some
significantly, including exposure duration, room height, and air exchange rates for the POTW
loader scenario. For the building height and air exchange rates, ISCORS developed three
values (for each parameter) that represent more typical conditions at POTWs, which
significantly reduced the DSRs and thus doses from Ra-226 and Th-228 for the worker
loading scenario. The report was revised accordingly.
Response: While it was noted that the sewage sludge density can vary considerably by the
type of sludge processing, the current approach was considered to be reasonably conservative
but realistic. The dose calculations were found to be relatively insensitive to milk and meat
consumption rates, so no changes were made. In some cases, no changes were made in the
scenarios and results, but the text was revised accordingly.
•• Comment: Why was Columbus, Ohio, used to represent the United States?
Response: ISCORS had no reason to consider changing the default location in CAP-88 (used
by RESRAD-OFFSITE), which has a strong predominant wind direction, and is a typical
mid-continent location providing reasonably conservative site conditions. In any case, the
three scenarios where RESRAD-OFFSITE was used, all have low DSR values.
•• Comment: Use of the upper 95th percentile DSRs is very conservative.
Response: ISCORS considers that the primary use of the calculated DSR values is for
screening purposes only for which 95th percentile is reasonable and is discussed further in the
final Recommendations document. Other DSR percentile values (i.e., 5, 10, 25, 50, 75, 90,
95, and mean) are provided in Appendix E.
ISCORS Technical Report 2004-03 F-4 Final, February 2005
-------
•• Comment: The compounding effect of assumptions can be significant.
Response: ISCORS agrees with this comment and tried to reduce conservatism for individual
parameters which had resulted in a compounding effect.
F.3.2.2 Radionuclides
•• Comment: Explain why, regardless of the activity, K-40 is not of concern.
Response: ISCORS added an explanation to the text that K-40 is a naturally occurring
radioactive material in fertilizers and food products that may concentrate in sewage sludge or
ash, and as such is of concern for this analysis. However, exposure to K-40 is only of
potential concern for external exposures. Internal exposures are not of concern, because of
the equilibrium of K-40 with nonradioactive potassium in the body. Therefore, the DSRs
calculated account for external exposures only.
•• Comment: The dominance of Ra-226 via radon in almost all scenarios was enlightening.
How do levels in sewage sludge compare with levels in native soils? Is there the possibility
that sometimes the sewage sludge dilutes Ra-226 levels in native soils?
Response: The recommendations report, in Table 5, and the Final Survey Report, in
Table 4.3, provide a comparison of concentrations in sewage sludge and ash to concentrations
in soil, fertilizer, and building materials. ISCORS does not believe this needs to be addressed
in this report.
ISCORS agrees that when sewage sludge contains little or no Ra-226, it could dilute
radionuclide levels in native soils; for conservatism, ISCORS does not believe this needs to be
addressed in this report.
F.3.2.3 Scenarios/Parameters—General
•• Comment: ISCORS should base the assessment on a number of real-world sites, not on
generic or hypothetical locations, geology, hydrology, situations, and scenarios.
•• Comment: The "closest" scenario may be significantly different from site-specific
conditions.
Response: While the use of real-world sites is a valid approach, ISCORS believes that the
current approach is sufficient to meet the charge to the Subcommittee. The current approach
also provides an opportunity to represent a wider population of potential sites.
•• Comment: The document has no ecological analysis.
Response: The dose modeling was performed to evaluate, in part, whether the presence of
radioactive materials in sewage sludge and ash could pose a threat to the health and safety of
POTW workers or the general public. Thus, no ecological analysis was performed.
Final, February 2005 F-5 ISCORS Technical Report 2004-03
-------
F.3.2.4 Onsite Resident Scenario
•• Comment: All meat and dairy products consumed are produced onsite (50% of the fruit,
vegetables, and fish): this is higher than for the recently completed Part 503 exposure/risk
assessment. ISCORS should justify this as it seems unreasonable.
Response: ISCORS agrees that the assumed consumption values were highly conservative.
However, the food pathway had negligible impact on the calculated doses, and no changes
were made to this report.
•• Comment: ISCORS should consider expanding scenarios to address future farm workers.
Why is the onsite resident scenario representative also of farm workers? Land application
workers are assumed to be exposed chronically, but farm workers are on the field much less.
•• Comment: For non-sludge-application agricultural workers, there is comparable exposure
time, more direct gamma dose (no shielding), and inadvertent ingestion of soil.
Response: There could be numerous potential exposure scenarios that may be plausible.
ISCORS selected those that were felt to be most typical and realistic. The recommendations
report discusses the need for considering other types of exposures, such as farm workers.
Thus, no changes were made to this report.
F.3.2.5 Landfill Neighbor Scenario
•• Comment: Liner fails sometime in the future; calculations are carried out for 1,000 years
(CO/CRCPD); fence prevents access for 1,000 years; reliance on State laws and deed
restrictions is wow-conservative.
Response: ISCORS believes that reliance on State laws and deed restrictions is a reasonable
assumption for modeling the most likely future scenarios. The recommendations report
mentions the possibility that site restrictions might not be followed. No changes to this report
were made.
F.3.2.6 Sludge Application Worker Scenario
•• Comment: The sludge application worker scenario may be improved if also made to
represent future farm field workers in fields.
Response: ISCORS believes the onsite resident provides a more conservative scenario than
that of farm field workers. There could be numerous potential exposure scenarios that may be
plausible. ISCORS selected those that were felt to be most typical and realistic. The
recommendations report discusses the need for considering other types of exposures, such as
farm workers. Thus, no changes were made to this report.
F.4 Modeling
•• Comment: In Equations 7.2 and 7.3 for DSR for Ra-226 and Th-228, it would be relatively
straightforward to develop a similar approach for all exposure scenarios and radionuclides, by
ISCORS Technical Report 2004-03 F-6 Final, February 2005
-------
identifying the three or four most sensitive parameters for each scenario and providing
equations to allow a user to vary parameters to fit local conditions.
Response: ISCORS agrees that additional fitting formulas could be useful to some POTW
operators to address site-specific conditions, if the consultation level is exceeded using the
screening process described in the Recommendations document. However, the dose modeling
was intended to provide screening calculations, and ISCORS does not find it necessary to
develop similar fitting formulas for all scenarios, because of the general insensitivity of dose
calculations to parameters other than source variability, as suggested by Table 7.3. For
common variable parameters, ISCORS has added a table to the recommendations report that
provides radon concentration screening levels for combinations of room heights and
ventilation rates. Another parameter that can be easily adjusted is time of exposure. If site
specific conditions exist where exposures are either less than or greater than 1,000 hours for a
POTW worker, for example, the DSR could be easily changed by multiplying by the ratio of
the site specific hours to 1,000 hours. (Example: If a worker only spent 500 hours per year
loading sludge, the DSR should be multiplied by 0.5.)
••Comment: Reproducibility is not addressed. Can the entire analysis be duplicated? Are the
results of the report reproducible, ready-made for emulation, given site-specific inputs?
Response: ISCORS attempted to describe the calculations in a manner that readers could
reproduce the results.
•• Comment: Attempts made to force-fit the source-term analyses into a source term model that
did not contain critical attributes (e.g., time-varying analysis)—although an adequate
alternative solution was implemented which involved more work and a confusing
presentation—should have considered additional models that addressed deficiencies in the
chosen set of models.
Response: ISCORS considered many codes for the dose calculations and determined that
RESRAD was the best overall choice. ISCORS believes that the source term calculations
used for multiple years of application provide adequate detail for these screening calculations.
•• Comment: The report should track the mass throughout the system to determine the fraction
that accounts for the dose and any subsequent risk.
Response: ISCORS believes that the suggestion is beyond the scope of the project and
believes that the methods used are adequate.
F.5 Sensitivity/Uncertainty
•• Comment: Choices of values used in the sensitivity/ uncertainty analysis (e.g., differences
between the 95th and 5th percentiles) appear to be unexpectedly small.
Response: ISCORS believes that the sensitivity/uncertainty analysis performed was
sufficient for the screening nature of the calculations.
Final, February 2005 F-7 ISCORS Technical Report 2004-03
-------
F.6 Validation
ISCORS agrees that model validation, as addressed in the following peer review comments, is an
important next step in assessments such as this, but such studies are beyond the scope of the
ISCORS study effort:
•• Comment: The results of the TLD influent monitoring program (from Feb'96-Dec'OO) for
Albuquerque, NM, might serve as a potential field validation site.
•• Comment: The document should address empirical testing of at least all of the POTW
worker scenarios, including use of spiked samples and measured exposures.
•• Comment: Some of the exposure scenarios, including all of the POTW worker scenarios, can
and should be tested.
ISCORS Technical Report 2004-03 F-8 Final, February 2005
-------
NRC FORM 335
(9-2004)
U.S. NUCLEAR REGULATORY COMMISSION
BIBLIOGRAPHIC DATA SHEET
(See instructions on the reverse)
1. REPORT NUMBER
(Assigned by NRC, Add Vol., Supp., Rev.,
and Addendum Numbers, if any.)
NUREG-1783
EPA 832-R-03-002A
DOE/EH-0670
2. TITLE AND SUBTITLE
ISCORS Assessment of Radioactivity in Sewage Sludge: Modeling to Assess Radiatbn Doses
3. DATE REPORT PUBLISHED
February
YEAR
2005
4. FIN OR GRANT NUMBER
5. AUTHOR(S)
Interagency Steering Committee on Radiation Standards (ISCORS), Sewage Sludge
Subcommittee
6. TYPE OF REPORT
7. PERIOD COVERED (Inclusive Dates)
8. PERFORMING ORGANIZATION - NAME AND ADDRESS (If NRC, provide Division, Office or Region, U.S. Nuclear Regulatory Commission, and mailing address; if contractor,
provide name and mailing address.)
Division of Waste Management and Environmental Protection
Office of Nuclear Material Safety and Safeguards
U.S. Nuclear Regulatory Commission
Washington, D.C. 20555-0001
9. SPONSORING ORGANIZATION - NAME AND ADDRESS (If NRC, type "Same as above"; if contractor, provide NRC Division, Office or Region, U.S. Nuclear Regulatory Commission,
and mailing address.)
same as above
10. SUPPLEMENTARY NOTES
11. ABSTRACT (200 words or less)
The treatment of municipal sewage at publicly owned treatment works (POTWs) leads to the production of considerable amounts
of residual solid material known as sewage sludge, which is widely used in agriculture and land reclamation. Elevated levels of
naturally-occurring and man-made radionuclides have been found in sewage sludge samples, suggesting the possible radiation
exposure of POTW workers and members of the public. The Interagency Steering Committee on Radiation Standards
(ISCORS) therefore conducted a limited survey of radioactivity in sewage sludge across the United States. Concurrently, to
assess the levels of the associated doses to people, it undertook to model the transport of the relevant radionuclides from
sewage sludge into the local environment. The modeling work consisted of two steps. First, seven general scenarios were
constructed to represent typical situations in which members of the public or POTW workers may be exposed to sewage sludge.
Then, the RESRAD multi-pathway environmental transport model generated sewage sludge concentration-to-dose conversion
factors. This Report describes the results of this dose modeling effort, and provides a complete description and justification of
the dose assessment methodology.
12. KEY WORDS/DESCRIPTORS (List words or phrases that will assist researchers in locating the report.)
Interagency Steering Committee on Radiation Standards, ISCORS, Sewage Sludge Subcommittee,
dose modeling, sewage sludge, dose assessment, sludge management, scenarios, municipal sewage,
publicly owned treatment facilities, POTW.
13. AVAILABILITY STATEMENT
unlimited
14. SECURITY CLASSIFICATION
(This Page)
unclassified
(This Report)
unclassified
15. NUMBER OF PAGES
16. PRICE
NRC FORM 335 (9-2004)
PRINTED ON RECYCLED PAPER
------- |