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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(NUREG–0750).
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 

Final, February 2005 iii ISCORS Technical Report 2004-03

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 v ISCORS Technical Report 2004-03

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
ISCORS Technical Report 2004-03 vi Final, February 2005

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
Final, February 2005 vii ISCORS Technical Report 2004-03

FIGURES

B.1 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, P/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, P/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, P/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

4.1a 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
ISCORS Technical Report 2004-03 viii Final, February 2005

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
Final, February 2005 ix ISCORS Technical Report 2004-03

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.11 RESRAD-BUILD Baseline Parameter Values and Distributions . . . . . . . . . . . . A-60

B.1 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-1

D.2 Time Fractions and WL to WLM Conversion Factors . . . . . . . . . . . . . . . . . . . . . D-1

E.1 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
ISCORS Technical Report 2004-03 x Final, February 2005

APPENDICES

A Baseline Parameter Values and Distributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1

A.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1

A.2 Parameters Used in Multiple Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1

A.3 Code-Specific Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-7

B RESRAD and RESRAD-BUILD Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1

B.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1

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-1

C.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1

C.2 Regulatory Values for Release Fraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1

C.3 Assessment of Aaberg et al. (1995a) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1

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-1

D.1 Dose- and Concentration-To-Source Ratios in Working Level Units . . . . . . . D-1

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-1

F Responses to Peer Review Comments on ISCORS Dose Modeling Document . . . . . . . . . F-1

F.1 Overview of Peer/General Review Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-1

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
Final, February 2005 xi ISCORS Technical Report 2004-03

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, NRC/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, NRC/Office of Nuclear Material Safety and Safeguards

Weihsueh Chiu, EPA/Office of Research and Development

Chris Daily, NRC/Office of Nuclear Regulatory Research

Mark Doehnert, EPA/Office of Radiation and Indoor Air

Giorgio Gnugnoli, NRC/Office of Nuclear Material Safety and Safeguards

Paula Goode, EPA/EPA/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, NRC/Office of Nuclear Regulatory Research

Anthony Huffert, NRC/Office of Nuclear Material Safety and Safeguards

Andrea Jones, NRC/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, NRC/Office of Nuclear Regulatory Research

Donna Moser, NRC/Region II, Division of Nuclear Materials Safety

Robert Neel, NRC/Office of Nuclear Material Safety and Safeguards

Bob Nelson, NRC/Office of Nuclear Material Safety and Safeguards

Tom Nicholson, NRC/Office of Nuclear Regulatory Research

Tom O’Brien, NRC/Office of State and Tribal Programs

William R. Ott, NRC/Office of Nuclear Regulatory Research

Hal Peterson, DOE/Office of Environment, Safety and Health

Alan Rubin, EPA/Office of Water

Steve Salomon, NRC/Office of State and Tribal Programs

Patricia Santiago, NRC/Office of Nuclear Material Safety and Safeguards

Dave Saunders, EPA/National Air and Radiation Environmental Laboratory

Duane Schmidt, NRC/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, NRC/Office of Nuclear Material Safety and Safeguards

Scott Telofski, EPA/National Air and Radiation Environmental Laboratory

Mary Thomas, NRC/RIII, Division of Nuclear Materials 
ISCORS Technical Report 2004-03 xii Final, February 2005

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
Final, February 2005 xiii ISCORS Technical Report 2004-03

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. 
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

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
Final, February 2005 xv ISCORS Technical Report 2004-03

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, I-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, and Xe-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,
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

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
Final, February 2005 xvii ISCORS Technical Report 2004-03

(Scenario 7) spend a considerable amount of time indoors, requiring the use of the RESRADBUILD 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 EPA’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
ISCORS Technical Report 2004-03 xviii Final, February 2005

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
Final, February 2005 xix ISCORS Technical Report 2004-03

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 95thpercentile 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.
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

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
Final, February 2005 xxi ISCORS Technical Report 2004-03

Table ES.1 Calculated Total Peak Dose from Survey Samples: Summary Results

With and Without Indoor Radon Contribution (mrem/year)

Scenario Subscenario

95% sample

Dominant

Radionuclide(s)

[pathways]

TEDE

(mrem/yr)

TEDE w/o Rn

(mrem/yr)

S1—Onsite

Resident

1 year of appl. 3 1 Ra-226 [indoor

radon] 5 14 4.9

20 55 16

50 * 130 37

100 * 260 69

S2—

Recreational User 

N/A 0.22 -- Ra-226 [external]

S3—Nearby Town 1 yr of appl. 3.2e-03 -- Ra-226 [outdoor

radon] 5 0.014 --

20 0.045 --

50 * 0.094 --

100 * 0.17 --

S4—Landfill MSW - Sludge 0.027 0.01 Ra-226 [indoor

radon]

MSW - Ash 0.041 0.014 Ra-226 [indoor

radon]

Impoundment 1.2 0.36 Ra-226 [indoor

radon]

S5—Incinerator N/A 7.7 -- multiple [multiple]

S6—Sludge

Application Worker

1 yr of appl. 0.15 -- Ra-226 [external]

5 0.77 --

20 3 --

50 * 7.4 --

100 * 15 --

S7—POTW

Workers

Sampling

(mrem/sample)

4.9e-07 -- Ra-226 [external]

Transport

(mrem/hr)

1.9e-04 5.6e-05 Th-228 [indoor

radon, external]

Loading 17–70§ 13 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.
ISCORS Technical Report 2004-03 xxii Final, February 2005

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,

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).
Final, February 2005 1-1 ISCORS Technical Report 2004-03

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.
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

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
Final, February 2005 1-3 ISCORS Technical Report 2004-03

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 Exposure Source

Primary Exposure 

Pathway

Hypothetical

Maximum Doses

(mrem/yr)

POTW sludge

process operator

Sludge in

processing

equipment

External 360

POTW incinerator

operator

Incinerator ash Inhalation of dust 340

POTW heavy

equipment operator

Sludge or ash in

truck

External 210

Farmers or

commercial operators

Land applied

sludge

Ingestion via local crops,

external

17

Landfill equipment

operator

Ash disposed in

landfill

External 64

Resident on former

landfill site

Ash disposed in

former landfill

Inhalation via resuspension

of dust, ingestion via

garden vegetables

170

Source: Kennedy et al. 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
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

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 (FGR 11, FGR 12, and FGR 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
Final, February 2005 1-5 ISCORS Technical Report 2004-03

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 2-1 ISCORS Technical Report 2004-03

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.
ISCORS Technical Report 2004-03 2-2 Final, February 2005

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.
Final, February 2005 2-3 ISCORS Technical Report 2004-03

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.
ISCORS Technical Report 2004-03 2-4 Final, February 2005

Table 2.1 Comparison of Models

Model Selection Criterion RESRAD

Family(1)

PRESTO

CLNCPG 

Vers. 4.2

GENII(2)

Vers. 2.0

DandD

Vers. 1.0

(1) Radionuclides of concern ×(3)

×××

(2) Environmental transport pathways × × × ×

(2.1) Resuspension × × × ×

(2.2) Groundwater infiltration and transport × × ×

(2.3) Surface water run-off (4) ×××

(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 of fish 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 ×

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.
Final, February 2005 2-5 ISCORS Technical Report 2004-03

Table 2.2 Scenarios and Models in this Assessment

Scenario Exposed

Individual*

Multiple

Applications

Model Code

Land Application

1. Onsite residents on-site T RESRAD Version 6

2. Recreational users—

reclamation

on-site T RESRAD Version 6

3. Residents of nearby town off-site T RESRAD-OFFSITE/

CAP-88

Landfill Disposal

4. Landfill neighbors—

sub-scenarios for MSW and 

impoundment

off-site T RESRAD-OFFSITE/

CAP-88

Incineration

5. POTW incinerator neighbors off-site T RESRAD-OFFSITE/

CAP-88

Occupational Exposure

6. Agricultural sludge

application worker

on-site T RESRAD Version 6

7. Indoor POTW worker—

subscenarios for different

POTW operations

on-site 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.
ISCORS Technical Report 2004-03 2-6 Final, February 2005

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 steadystate 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.
Final, February 2005 2-7 ISCORS Technical Report 2004-03

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, dsrj

(t), as a function of

time. The program then searches for the global maximum in dsrj(t), which we call DSR j , for

every realization. (The maxima in dsrj

(t) is likely to occur at different times for different

realizations, or values of the index j .)

The values of DSR j 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. 
ISCORS Technical Report 2004-03 2-8 Final, February 2005

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. 
Final, February 2005 2-9 ISCORS Technical Report 2004-03

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. 

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

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. 
ISCORS Technical Report 2004-03 3-2 Final, February 2005

Table 3.1 Radionuclides Included in the Dose Assessment

RadionuclideMajor

Radiations Half-life Radionuclide

Major

Radiations Half-life

Ac-227c alpha, beta,

gamma

22 years Po-210b alpha 138 days

Ac-228d beta, gamma 6 hours Pu-238 alpha 88 years

Am-241 alpha, gamma 432 years Pu-239 alpha 24×10 3 years

Be-7a gamma 53 days Ra-223d alpha, gamma 11 days

Bi-212d alpha, beta,

gamma

61 minutes Ra-224d alpha, gamma 4 days

Bi-214d beta, gamma 20 minutes Ra-226 alpha, gamma 1600 years

C-14 beta 5,730 years Ra-228 beta 6 years

Ce-141 beta, gamma 33 days Rn-219d alpha, gamma 4 seconds

Co-57 gamma 271 days Sm-153a beta, gamma 47 hours

Co-60 beta, gamma 5 years Sr-89 beta 51 days

Cr-51a gamma 28 days Sr-90 beta 29 years

Cs-134 beta, gamma 2 years Th-227d alpha, gamma 19 days

Cs-137 beta, gamma 30 years Th-228 alpha, gamma 2 years

Eu-154 beta, gamma 9 years Th-229b alpha, gamma 7,340 years

Fe-59 beta, gamma 45 days Th-230 alpha 77×10 3 years

H-3 beta 12 years Th-232 alpha 14×10 9 years

I-125 gamma 60 days Th-234d beta, gamma 24 days

I-131a beta, gamma 8 days Tl-201a gamma 3 days

In-111a gamma 3 days Tl-202a gamma 12 days

K-40 beta, gamma 1.3×10 9 years Tl-208d beta, gamma 3 minutes

La-138a beta, gamma 135×10 9 years U-233b alpha 158.5×103

 years

I-131a beta, gamma 8 days Tl-201a gamma 3 days

In-111a gamma 3 days Tl-202a gamma 12 days
Final, February 2005 3-3 ISCORS Technical Report 2004-03

Table 3.1 Radionuclides Included in the Dose Assessment (continued)

RadionuclideMajor

Radiations Half-life Radionuclide

Major

Radiations Half-life

I-131a beta, gamma 8 days Tl-201a gamma 3 days

In-111a gamma 3 days Tl-202a gamma 12 days

K-40 beta, gamma 1.3×10 9 years Tl-208d beta, gamma 3 minutes

La-138a beta, gamma 135×10 9 years U-233b alpha 158.5×103

 years

Np-237b alpha, gamma 2.14×106 years U-234 alpha 245×10 3 years

Pa-231b alpha, gamma 32.8×103 years U-235 alpha, gamma 700×10 6 years

Pa-234md beta, gamma 1 minute U-238 alpha 4.5×10 9 years

Pb-210 beta, gamma 22 years Xe-131md gamma 12 days

Pb-212d beta, gamma 11 hours Zn-65 beta, gamma 244 days

Pb-214d beta, gamma 27 minutes

Source: EPA 1999b.

Notes:

Information on daughters for standard RESRAD radionuclides is included in Tables 3.1and 3.2 of the RESRAD

manual (Yu et al., 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 I-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.
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

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 Asludge [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 3.1a) is then

Asoil = Asludge × S / (d × r) (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
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

value of r = 1520 kg/m3 is the mean of the soil density distribution presented in NRC (2000b).6

Inserting these in Equation 3.1a yields Equation 3.1b,

Asoil = 0.16 Bq/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 D1 

prob. In Equation 3.2, this is then scaled for multiple applications by means of a

factor, Fn ,

Dn 

prob = D1 prob × Fn (3.2)
ISCORS Technical Report 2004-03 3-6 Final, February 2005

where Fn is defined as the ratio, [Dn 

prob /D1 prob], 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 t = 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 j = 0 to n –1:

Dn (t) = 3 D(

(t – j) , [ j = 0, ... , n – 1 ] , (3.3a)

where this expression is meaningful only with the constraint (Equation 3.3b) 

t $ (n –1) . (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 n-th)

application, in year (n – 1 + r). The dose from all applications combined is still given by

Equation 3.4a,

Dn (t) = 3 D(

(t – j) , [ j = 0, ... , n – 1 ] , (3.4a)

but Equation 3.3b is replaced by Equation 3.4b,

t $ (n – 1 + 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
Final, February 2005 3-7 ISCORS Technical Report 2004-03

first become exposed, so that tr = t – (n – 1 + r). We also transform the index k = (n – 1 + r) ! j, 

so that Equations 3.3a and 3.3b become

Dn (tr) = 3 D((tr + k) , [k = r, ... , r + n – 1] , and tr $ 0 . (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 = 1 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(t r)] / max[D(

(t)] , (3.6a)

or, defining t

 max as the time where D(t) is greatest as in Equation 3.6b, then

Fn = Dn (tr

max) / D(

(t

 max) , (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,

Dn

prob = D1 prob × Dn (trmax) / D(

(tmax) . (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 D(

(t) occurs at t = 0, then

the F1 < 1. 

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
ISCORS Technical Report 2004-03 3-8 Final, February 2005

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 (P/Q, or “chi over Q”), the ratio that relates air concentration at

a target position downwind, P (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 P/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, P/Q, for the

Various Radionuclides, Computed for the Nearby Town Scenario by

CAP88-PC, for Input to RESRAD-OFFSITE

Isotope—Nearby Town Deposition Velocity (m/s) P/Q (at 800 m) (s/m 3 )

H-3, C-14, Xe-131m, Rn-222 0 7.4×10 – 6

Rn-220 0 2.3×10 – 7

I-125, I-131 0.035 8.9×10 – 7

All others 0.002 6.0×10 – 6

Once P/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.
Final, February 2005 3-9 ISCORS Technical Report 2004-03

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 Value

Activity due to Sewage Sludge/Ash 0.925 Bq/kg (0.025 pCi/g)

Saturated Hydraulic Conductivity 10-3 cm/s

Particle Density 2600 kg/m3

 – 4700 kg/m3

Porosity 0.671

Bulk Density (derived) 860 kg/m3

 – 1500 kg/m3

Field Capacity 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 P/Q go through a maximum at

150 meters, given in Table 3.4.
ISCORS Technical Report 2004-03 3-10 Final, February 2005

Table 3.4 Values of Deposition Velocity and Dispersion Factor, P/Q, for the

Various Radionuclides, Computed for the Landfill Neighbor Scenario

by CAP88-PC, for Input to RESRAD-OFFSITE

Isotope—Nearby Town Deposition Velocity (m/s) P/Q (at 150 m) (s/m 3 )

H-3, C-14, Xe-131m, Rn-222 0 1.7×10 – 4

Rn-220 0 4.8×10 – 5

I-125, I-131 0.035 5.1×10 – 5

All others 0.002 1.6×10 – 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 A sludge and feed rate R feed , the rate

of radionuclide release from the incinerator stack, R release , is given by Equation 3.7,

R release = A sludge × R feed × (1 – CE) , (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. 
Final, February 2005 3-11 ISCORS Technical Report 2004-03

Table 3.5 Incinerator Control Efficiencies, CE, and Release Rates, R release , for

Various Radionuclides

Isotope Control Efficiency Release Rate

Radon 0.0 1.76x108 Bq/yr (4.75 × 10-3 Ci/yr)

Carbon 0.05 1.67x108 Bq/yr (4.51 × 10-3 Ci/yr)

Tritium 0.1 1.58x108

 Bq/yr (4.27 × 10-3 Ci/yr)

Technetium 0.1 1.58x108 Bq/yr (4.27 × 10-3 Ci/yr)

Iodine 0.3 1.23x108

 Bq/yr (3.32 × 10-3 Ci/yr)

All Other Metals 0.9 1.76x107

 Bq/yr (4.75 × 10-4 Ci/yr)

A feed rate of R feed = 13 metric tons (13 × 10 3 kg) of dry sludge per day (or 4.75 × 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 P/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. 
ISCORS Technical Report 2004-03 3-12 Final, February 2005

Table 3.6 Values of Deposition Velocity and Dispersion Factor, P/Q, for the

Various Radionuclides, Computed for the Incinerator Neighbor

Scenario by CAP88-PC, for Input to RESRAD-OFFSITE

Isotope—Nearby Town Deposition Velocity (m/s) P/Q (at 150 m) (s/m 3 )

H-3, C-14, Xe-131m, Rn-222 0 1.1 × 10 – 5

Rn-220 0 5.8 × 10 – 6

I-125, I-131 0.035 1.1 × 10 – 5

All others 0.002 1.1 × 10 – 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 I-131 is 0.032, while for long-lived radionuclides, the decay factor is 1. The decay factors

are given in Table 3.7 below.
Final, February 2005 3-13 ISCORS Technical Report 2004-03

Table 3.7 Decay Factor Adjustments for Incinerator Neighbor Scenario

Radionuclide Decay Factor for

1 year

Radionuclide Decay Factor

for 1 year

Ac-227 0.98 Po-210 0.46

Am-241 1.00 Pu-238 1.00

Be-7 0.21 Pu-239 1.00

C-14 1.00 Ra-226 1.00

Ce-141 0.13 Ra-228 0.94

Co-57 0.65 Sm-153 0.0077

Co-60 0.93 Sr-89 0.20

Cr-51 0.11 Sr-90 0.99

Cs-134 0.85 Th-228 0.85

Cs-137 0.99 Th-229 1.00

Eu-154 0.96 Th-230 1.00

Fe-59 0.99 Th-232 1.00

H-3 0.97 Tl-201 0.012

I-125 0.23 Tl-202 0.047

I-131 0.032 U-233 1.00

In-111 0.012 U-234 1.00

K-40 1.00 U-235 1.00

La-138 1.00 U-238 1.00

Np-237 1.00 Xe-131m 0.047

Pa-231 1.00 Zn-65 0.62
ISCORS Technical Report 2004-03 3-14 Final, February 2005

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
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

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 lbs) (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.

Final, February 2005 4-1 ISCORS Technical Report 2004-03

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
ISCORS Technical Report 2004-03 4-2 Final, February 2005

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 4.1a. 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 of fish 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.11 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 4.1b. 

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
Final, February 2005 4-3 ISCORS Technical Report 2004-03

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%),

I-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 4.1b. 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 n-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 4.1b (the assumptions on site water versus town water, on well water

versus surface water, etc.) appears to be much less than that in Table 4.1a 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.
ISCORS Technical Report 2004-03 4-4 Final, February 2005

Table 4.1a Onsite Resident Scenario Pathways

Human

Exposure Environmental 

Pathway

Included? Comments

External radiation Direct exposure Yes Agricultural field; soil / sludge mixture 15 cm

deep

Inhalation

Resuspended dust Yes Mass loading represents an average value; dust

from top 15 cm (mixture region)

Indoor radon Yes

House sits on contaminated zone surface;

diffusion in through slab foundation; exchange

with outdoor air; radon also from water. 

Outdoor radon Yes Radium in contaminated soil

Ingestion of water

Groundwater Yes 90% ingested water from onsite well, 

10% from uncontaminated sources

Surface water No People with wells generally do not drink

surface water.

Ingestion of

plants

Irrigation water Yes 50% from well, 50% from surface waters

Dust Deposition Yes Plants contaminated through foliar deposition

of dust.

Root uptake Yes Plants contaminated through root uptake.

Ingestion of

meat / milk

Livestock water Yes 50% from well, 50% from surface waters

Livestock soil Yes Soil consumption by livestock

Fodder

Irrigation

water Yes

Root uptake of, and foliar deposition of,

contaminated water. Water 50% from well,

50% from surface waters.

Dust

deposition Yes Foliar deposition of dust

Root

uptake Yes Root uptake from contaminated soil

Ingestion of fish Surface Yes Consumption of fish from contaminated

surface water

Ingestion of soil Surface soil Yes Dirt from hands, etc. Pica child not

considered.
Final, February 2005 4-5 ISCORS Technical Report 2004-03

Table 4.1b Onsite Resident Scenario and Sub-Scenario Parameters and

Distributions

Subscenario Parameter Value/Distribution Comments

 1 

(Uncertainty)

Appendix A Baseline

distributions, values,

except...

Probabilistic, except

land area

 1 Years of application 1 All other parameter

values and distributions

are baseline from

Table A.7.

 2–6 

(Deterministic)

Appendix A Baseline

values, except...

Deterministic

 All Log or linear

spacing

Linear So as to obtain annual

dose results for each

year

 All No. of graphic

points

1024 Maximum permitted by

RESRAD. Data from

graphical points (one at

each year from 0 to

1023) are used to

calculate scaling

factors.

 2 Years of application 1 Replace distributions

with point values (see

Sections 2.4.2, 3.2.2)

 3 Years of application 5 "

 4 Years of application 20 "

 5 Years of application 50 "

 6 Years of application 100 "

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
ISCORS Technical Report 2004-03 4-6 Final, February 2005

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.
Final, February 2005 4-7 ISCORS Technical Report 2004-03

Table 4.2a Recreational User on Reclaimed Land Pathways

Human

Exposure Environmental Pathway PathwayIncluded? Comments

External

radiation Direct exposure Yes

Inhalation

Resuspended dust Yes

Indoor radon No

Outdoor radon Yes

Ingestion of

water

Groundwater Yes All well water

Surface water No

Ingestion of

plants

Irrigation water No No farming, irrigation

Dust deposition No

Root uptake No

Ingestion of

meat / milk

Livestock (game) water Yes Deer drink surface water.

Livestock (game) soil Yes

Fodder

Irrigation water No No irrigation

Dust deposition Yes

Root uptake Yes Vegetation for deer grows in

contaminated soil.

Ingestion of

fish Surface water Yes

Ingestion of

soil Surface soil Yes
ISCORS Technical Report 2004-03 4-8 Final, February 2005

Table 4.2b Recreational User Scenario Parameters and Distributions

Parameter Value/Distributions Comments

Livestock (i.e., deer)

water contamination

fraction

1

Plant food contamination

fraction

0

Meat (deer)

contamination fraction 

1

Aquatic food

contaminated fraction

1

Livestock fodder intake

for meat (kg/d)

2.7 kg/d From Wildlife Exposure Factors

Handbook (EPA 1993b), Allometric

Equations for herbivore mammals for a

250 lb (~114 kg) deer (Whitetail deer

from Nebraska Game and Parks

Commission) 

Livestock water intake

for meat (L/d)

7 L/d From (EPA 1993b) Allometric Equations

Livestock intake of soil

(kg/d) 

0.02 Deer prefer leafy plants. Value obtained

by scaling the Baseline rate of ingestion

of grass by a cow. Assume all vegetation

eaten onsite.

Groundwater fraction for

livestock water

0 Deer drink only surface water.

Storage time for meat (d) 182.5 Deer meat consumed over 365 d.

Storage time for fish (d) 0 Fish eaten right away.

Meat transfer factor

(pCi/kg per pCi/d)

Baseline values Use cattle values and distributions as was

done in the Part 503 rule.
Final, February 2005 4-9 ISCORS Technical Report 2004-03

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.
ISCORS Technical Report 2004-03 4-10 Final, February 2005

Table 4.3a Nearby Town Resident Pathways

Human

Exposure

Environmental

Pathway

Pathway

Included? Comments

External

radiation Direct exposure Yes

Contamination of surface soil in town;

dust deposited by airborne transport from

the field

Inhalation

Suspended dust Yes Atmospheric transport from

contaminated field

Indoor radon No

Diffusion of radon into basements from

surrounding soil; nearly all radon

entering basements will be from native,

local soil, not from sludge. 

Outdoor radon Yes Air transport and radon emanation from

deposition of contaminated dust

Ingestion

of water

Groundwater No 

Town uses treated and monitored water,

so actual radionuclide content would not

exceed MCLs.

Surface water No Town uses treated and monitored water.

Ingestion

of plants

Irrigation water No Town uses treated and monitored water.

Dust deposition Yes

Root uptake Yes Root uptake from soil contaminated by

atmospheric transport.

Ingestion

of

meat/ milk

Livestock water No Town uses treated and monitored water.

Livestock soil Yes

Fodder

Irrigation

water No Town uses treated and monitored water.

Dust

deposition Yes

Root

uptake Yes 

Ingestion

of fish Surface water Yes

Ingestion

of soil Surface soil Yes Atmospheric transport fromcontaminated agricultural field.
Final, February 2005 4-11 ISCORS Technical Report 2004-03

Table 4.3b Nearby Town Resident Scenario and Sub-Scenario Parameters and

Distributions

Subscenario Parameter Value/Distribution Comments

1 

(Uncertainty)

Appendix A baseline

values and

distributions, except...

1 Years of application 1 yr

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

0

0

0

0

0

0

0

0

Household water and

irrigation water are not

contaminated. They are

not from a local well or

surface water body.

Fraction of water from well 0 Household water and

irrigation water are not

contaminated

c/Q, all see Table 3.2

2–6

(Deterministic)

Appendix A baseline

and Subscenario 1

values, except...

all Number of intermediate time

points

1024 To obtain annual dose

results for the considered

time frame of 1000 years.

all Times at which output is

reported

1023 To obtain annual dose

results for the considered

time frame of 1000 years

 2 Years of application 1 yr

 3 Years of application 5 yrs

 4 Years of application 20 yrs NA

5 Years of application 50 yrs NA

6 Years of application 100 yrs NA
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

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 water 9 (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
Final, February 2005 4-13 ISCORS Technical Report 2004-03

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.
ISCORS Technical Report 2004-03 4-14 Final, February 2005

Table 4.4a Landfill Neighbor Pathways—Post-Monitoring Period

Human

Exposure Environmental Pathway

Pathway

Included? Comments

External

radiation Direct exposure Yes

Inhalation

Suspended dust Yes Cover has been eroded/disturbed.

Indoor radon No House is not on sludge disposal

site.

Outdoor radon Yes Cover has been eroded /disturbed.

Ingestion of

water

Groundwater Yes 90% ingested water from well, 

10% from uncontaminated sources

Surface water No

Ingestion of

plants

Irrigation water Yes 50% from well, 50% from surface

waters, foliar deposition of water

Dust deposition Yes Mainly from air dispersion of the

sludge material

Root uptake Yes

Soil becomes contaminated

because of deposition of

radionuclides resulting from air

dispersion and irrigation. 

Ingestion of

meat / milk

Livestock water Yes 50% from well, 50% from surface

waters

Livestock soil Yes

Fodder

Irrigation water Yes 50% from well, 50% from surface

waters, root uptake

Dust deposition Yes

Root uptake Yes 

Ingestion of

fish Surface water Yes

Surface water becomes

contaminated through runoff of

radionuclides from the landfill.

Ingestion of

soil Surface soil Yes
Final, February 2005 4-15 ISCORS Technical Report 2004-03

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) Decay/ingrowth for 30 years

Initial activity: 

Subscenarios 1 & 2 = 0.025 pCi/g;

Subscenarios 3 & 4 = 1 pCi/g

See Chapter 3.

Primary Contamination Area

Parameters

Area of primary contamination

(m2 )

10,000 About 2 acres 

(EPA, 1988b)

Length of contamination parallel

to aquifer flow (m)

100 Square root of area

Depth of soil mixing layer (m) 0.15 Default plowing depth

Runoff coefficient 0.916/Uniform(0.413, 0.916) To get an infiltration rate ranging

from 0.03 m/yr to 0.22 m/yr

Irrigation applied per year (m/yr) 0 No irrigation on the landfill area

Cover

Thickness (m) 0.5 Standard thickness for clay layer

Bulk density (g/cm3

) 1.52

Total porosity 0.427 HELP model default (Schroeder

et al, 1994)

Soil erodibility factor 0.3 Default value of

RESRAD-Offsite, results in

erosion rate of 0.001 m/yr.

Volumetric water content 0.427 Set to the total porosity value to

obtain the desired infiltration rate.

Contaminated Zone

Thickness (m) 2 Total 20,000 m3

 of sludge or

waste

Total porosity 0.671 for MSW landfill and 0.427

for surface impoundment

From Table 3.3 for MSW landfill,

for surface impoundment, the

value corresponds to that of

sewage sludge.

Dry bulk density (g/cm3

) 1.18 for MSW landfill and 1.52

for surface impoundment 

The average value of the range as

specified in Table 3.3 is 1.18.
ISCORS Technical Report 2004-03 4-16 Final, February 2005

Table 4.4b Landfill Neighbor Scenario Parameter and 

Distributions—Post-Monitoring Period (continued)

Parameter Value / Distribution Comments

Field capacity 0.292 for MSW landfill and 0.2

for surface impoundment

From Table 3.3 for MSW landfill,

0.2 is the RESRAD default value.

Hydraulic conductivity (m/yr) 315 for MSW landfill;

9.974/{Bounded LogNormal (2.3,

2.11, 0.004, 9250)} for surface

impoundment

From Table 3.2 for MSW landfill,

soil value for surface

impoundment

Unsaturated zone 1 (liner)

Thickness (m) 0.5 Standard thickness for clay layer

Hydraulic conductivity (cm/s) 0.03 / {Uniform(0.03,0.22)} Same as the infiltration rate

Total Porosity 0.427 HELP model default (Schroeder

et al., 1994)

Air Transport Parameters

Ingrowth factor for Rn -222

progeny

0.265

 c/Q, all see Table 3.4 Adjusted CAP88PC value for a

wind speed of 4.24 m/s at 150 m

Groundwater Transport

Parameters

Distance from down-gradient

edge of contamination to well in

the direction parallel to aquifer

flow (m)

150 Collocate the well with the

receptor.

Distance from down-gradient

edge of contamination to surface

water body in the direction

parallel to aquifer flow (m)

150 Collocate the surface water body

with the receptor

External Radiation Shape and

Area Factor

Off-site

 Scale (m) 600

 Receptor location X (m) 506 Circular landfill, 56 m radius,

receptor is 150 m from its edge.

 Receptor location Y (m) 300
Final, February 2005 4-17 ISCORS Technical Report 2004-03

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.
ISCORS Technical Report 2004-03 4-18 Final, February 2005

Table 4.5a Incinerator Neighbor Pathways

Exposure

Pathway Environmental Pathway

Pathway

Included? Comments

External

radiation Direct exposure Yes Plume submersion andgroundshine 

Inhalation

Plume inhalation Yes

Exposed individual placed in

the sector with highest

concentration

Indoor radon No

Outdoor radon Yes In plume, and emanating from

deposited radionuclides

Ingestion of

water

Groundwater No

Surface water No

Ingestion of

plants

Irrigation water No

Dust deposition Yes

Root uptake Yes Surface deposition of

transported nuclides

Ingestion of

meat / milk

Livestock water No

Livestock soil Yes

Fodder

Irrigation water No

Dust deposition Yes

Root uptake Yes

Ingestion of fish Surface Water No

Ingestion of soil Surface soil Yes Deposition of transported

effluent
Final, February 2005 4-19 ISCORS Technical Report 2004-03

Table 4.5b Incinerator Neighbor Scenario Parameters and Distributions

Parameter Value / Distributions Comments

Dispersion Calculation in CAP88-PC

Lid Height (m) 1,000

Stack Height (m) 13 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

Stack Diameter (m) 1 Easterly incinerator

Stack Exit Velocity (m/sec) 1 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)

For each radionuclide

of concern

Sediment delivery ratio 0 No primary soil contamination source,

therefore, no contaminant delivery to

surface water

c/Q, all see Table 3.6

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 

0

0

0

0

0

0

0

Household water and irrigation water

are not contaminated because there is

no primary soil contamination source. 
ISCORS Technical Report 2004-03 4-20 Final, February 2005

Table 4.5b Incinerator Neighbor Scenario Parameters and Distributions

(continued)

Parameter Value / Distributions Comments

Fraction of water from well 0 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)

0 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.
Final, February 2005 4-21 ISCORS Technical Report 2004-03

Table 4.6a Agricultural Application Worker Pathways

Exposure

Pathway Environmental Pathway

Pathway

Included? Comments

External radiation Direct exposure Yes

Inhalation

Resuspended dust Yes

Indoor radon No

Outdoor radon Yes

Ingestion of water

Groundwater No

Surface water No

Ingestion of plants

Irrigation water No

Dust deposition No

Root uptake No

Ingestion of

meat / milk

Livestock water No

Livestock soil No

Fodder

Irrigation water No

Dust deposition No

Root uptake No

Ingestion of fish Surface Water No

Ingestion of soil Surface soil No

Assume industrial hygiene

practices

 
ISCORS Technical Report 2004-03 4-22 Final, February 2005

Table 4.6b Agricultural Application Worker Scenario Parameters and

Distributions

Subscenario Parameter Value / Distribution Comments

1 

(Uncertainty)

Appendix A baseline

values, distribution

Years of application 1 yr

Times for

Calculation (yr)

1 Worker is only present

during the application of

sludge

Cover (shielding)

thickness (m)

0.003 Based on observed sludge

application equipment

Cover (shielding)

density

7.87 density of steel

Cover (shielding)

erosion

0 No erosion of the shielding

Receptor distance

from the ground, m

1

Inhalation rate

(m3

/yr)

14,600, Triangular

(4750, 7300, 28900)

Inhalation rate distribution

for adult male for typical

outdoor activity levels from

NRC (2000b) (NUREG/CR6697).

Mass loading for

inhalation (g/m3

)

3×10 – 4 , 

Uniform (1×10 – 4 ,

5×10 – 4 )

Values are for average

conditions outdoor during

gardening from NRC

(1992b) (NUREG/CR-5512,

Volume 1)

Exposure Duration

(y)

1 Worker is only present

during the application of

sludge

Indoor time fraction 0 Worker is engaged in

application of sludge at the

field

Outdoor time

fraction

0.23 Based on the assumption that

the application worker

spends 8 h/d for 250 d/yr in

the field.
Final, February 2005 4-23 ISCORS Technical Report 2004-03

Table 4.6b Agricultural Application Worker Scenario Parameters and

Distributions (continued)

Subscenario Parameter Value / Distribution Comments

2 – 6 

(Deterministic)

Appendix A baseline

and Subscenario 1

values, except...

Not applicable

All Log / linear spacing Linear To obtain annual dose results

for each year

Number of graphic

points

1024 To obtain the largest number

of annual doses in a single

run

2 Years of application 1 NA

3 Years of application 5 NA

4 Years of application 20 NA

5 Years of application 50 NA

6 Years of application 100 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
ISCORS Technical Report 2004-03 4-24 Final, February 2005

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
Final, February 2005 4-25 ISCORS Technical Report 2004-03

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. 
ISCORS Technical Report 2004-03 4-26 Final, February 2005

Table 4.7a All POTW Worker Pathways

Exposure

Pathway Environmental Pathway

Pathway

Included? Comments

External radiation

Direct exposure Yes All cases

Submersion Yes Immersion in cloud of dust,

only for biosolids loading

Inhalation

Resuspended dust Yes Only for biosolids loading

Indoor radon Yes Only for transport and

biosolids loading

Outdoor radon No

Ingestion of

water

Groundwater No

Surface water (runoff) No

Ingestion of

plants

Irrigation water No

Dust deposition No

Root uptake No

Ingestion of

meat / milk

Livestock water No

Livestock soil No

Fodder

Irrigation water No

Dust deposition No

Root uptake No

Ingestion of fish Surface Water No

Ingestion of soil Surface soil No Assumes industrial hygiene

practices eliminate ingestion
Final, February 2005 4-27 ISCORS Technical Report 2004-03

Table 4.7b General POTW Worker Sub-Scenario Parameters and Distributions

Subscenario Parameter Value / Distribution Comments

1 - Sludge

sampling

(Deterministic)

Appendix A baseline 

values, except...

Exposure Duration

(d)

1

Indoor Fraction 3.47×10 – 3 To get a total exposure

time of 5 minutes

Max. No. of Points

for Time Integration

1 Instantaneous dose is

calculated

Source Type Point

Activity

Concentration, pCi

75

Air Release Fraction 0 To suppress all air

dependent pathways

Receptor Location (0, 0, 0.5) Receptor at a distance of

0.5 m from the source

2 - Processing

(Deterministic)

Appendix A baseline

values, except...

Exposure Duration

(d)

1 Scenario definition

Indoor Fraction 4.17×10 –2 To get a total exposure

time of 1 hour

Max. No. of Points

for Time Integration

1 Instantaneous dose is

calculated

Source Type Line

Source Direction X

Source Length (m) 50 

Activity

Concentration, pCi/m

3,000 Scenario definition
ISCORS Technical Report 2004-03 4-28 Final, February 2005

Table 4.7b General POTW Worker Sub-Scenario Parameters and Distributions

(continued)

Subscenario Parameter Value / Distribution Comments

2 - Processing

(Deterministic)

Air Release Fraction 0 or 0.357 Zero, to suppress all air

dependent pathways for

all radionuclides except

for radon precursors,

where air release fraction

of 0.357 is used

Removable Fraction 0.1

Radon Release

Fraction

0.1

Source Lifetime, d 10,000

Receptor Location (0,0,3) Receptor at a distance of

3 m from the source

3 - Biosolids

loading

(Probabilistic)

Appendix A baseline

distributions, values,

except...

Indoor Fraction 0.114 To get a total exposure

time of 1,000 hours in one

year

4 - Biosolids

loading

(Deterministic)

Appendix A baseline

values, except...

Indoor Fraction 0.114 To get a total exposure

time of 1,000 hours in one

year
Final, February 2005 5-1 ISCORS Technical Report 2004-03

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.
10 Additional correlations may need to be considered for specific sites.

ISCORS Technical Report 2004-03 5-2 Final, February 2005

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 The possibility of rapid transport

due to fracture flow and/or

colloidal transport.

Variability of published measured

or estimated values.

Total and Effective Porosities — Variability of published measured

or estimated values based on

national databases.

Hydraulic Conductivities The possibility of rapid transport

due to fracture flow and/or

colloidal transport.

Variability of published measured

or estimated values based on

national databases.

Soil b parameter — Variability of published measured

or estimated values.
Final, February 2005 5-3 ISCORS Technical Report 2004-03

Table 5.1 Parameters and their Uncertainties and Variability (continued)

Parameter Uncertainty Characterized by

Distribution

Variability Characterized by

Distribution

Hydraulic Gradient — Variability of published measured

or estimated values.

Unsaturated Zone Thickness — Variability across continental U.S.

Well pump intake depth Uncertainty in actual intake depths Variability in aquifer thicknesses.

Depth of Soil Mixing Layer — Variability in natural (wind,

precipitation) and man-made

processes (tillage).

Human Intake Parameters

Inhalation Rate — Variability in adults due to

differences in long-term patterns of

time and activity.

Soil Ingestion Rate Uncertainty in adults due to limited

data.

Variability in adults. Distribution

includes mean rate for children.

Drinking Water Ingestion Rate — Variability in adults.

Milk Consumption Rate Uncertainty due to limited data and

changes over time.

Variability across adults and

children.

Crops and Livestock Parameters

Plant, Meat, Milk, and Fish

Transfer factors

Uncertainty in the transfer factor

method.

Variability among different sites

and foodstuffs.

Depth of roots — Variability amongst different plant

types and growing conditions

Building Characteristics parameters

Indoor dust filtration factor — Variability amongst different

buildings, climates, and seasons.

External Gamma Shielding

Factor

— Variability amongst different home

constructions

Other parameters

Resuspension Rate Uncertainty due to limited data. Variability amongst different sites.

Shielding Density — Variability amongst different

substances.

Note:

Additional detail on these parameters and others can be found in Yu et al. 2000.
ISCORS Technical Report 2004-03 5-4 Final, February 2005

Table 5.2 Parameter Uncertainty/Variability Results

Ratio of 95% DSR to 5% DSR

RadionuclideOnsite

Resident

Recreational

User

Nearby

Town

Landfill

(MSW)

Neighbor

Landfill

(Surface

Impoundment)

Neighbor

Incinerator

Neighbor

Sludge

Application

Worker

POTW

Worker

(loading)

Ac-227 2.9 1.2 6.2 114.7 53.6 2.0 4.5 4.8

Am-241 5.6 1.2 6.4 185.1 90.9 2.0 8.7 14.8

Be-7 2.2 1.0 7.3 1.0 1.0 3.0 1.1 1.0

C-14 76.1 557.7 2.0 1.0 4.2E+12 2.1 4.7 1.3

Ce-141 2.2 1.0 4.2 1.0 1.0 1.7 1.0 1.0

Co-57 2.3 1.1 12.7 1.0 1.0 5.4 1.1 1.0

Co-60 2.3 1.1 9.6 1.1E+03 404.8 3.8 1.2 1.0

Cr-51 2.2 1.1 9.0 1.0 1.0 4.4 1.1 1.0

Cs-134 2.3 1.1 18.7 1.0 1.0 4.6 1.1 1.0

Cs-137 2.7 1.1 14.9 110.4 63.2 5.2 1.1 1.0

Eu-154 2.2 1.1 8.2 412.2 95.9 2.6 1.1 1.0

Fe-59 2.2 1.1 9.0 1.0 1.0 4.3 1.1 1.0

H-3 8.9 11.8 3.9 1.0 8.2E+29 2.1 5.2 18.8

I-125 12.8 5.3 8.6 1.0 1.0 6.0 1.8 1.0

I-131 2.5 1.1 8.6 1.0 1.0 6.0 1.1 1.0

In-111 2.2 1.0 7.7 1.0 1.0 5.1 1.0 1.0

K-40 2.2 1.2 8.55 1.2E+08 2.1E+07 4.7 1.2 1.0

La-138 8.0 4.1 14.7 4.1E+32 6.1E+33 5.4 5.7 1.0

Np-237 74.9 744.8 6.8 4.8E+08 2.8E+08 2.0 3.0 213.3

Pa-231 22.1 22.9 17.7 3.3E+04 5.0E+03 2.0 19.6 9.6

Pb-210 9.9 3.0 6.1 81.4 77.2 1.9 5.2 6.4

Po-210 20.2 7.8 4.8 1.0 1.0 2.5 12.2 99.1

Pu-238 7.0 1.2 6.1 11.9 1.1 2.0 12.6 187.5

Pu-239 6.8 1.2 5.8 11.6 12.5 2.0 12.7 251.9

Ra-226 1.2 1.1 1.0 1.5 1.3 3.0 1.0 1.0–1.8*

Ra-228 2.4 1.1 1.1 11.1 12.1 2.1 1.1 1.0

Sm-153 2.1 1.0 6.4 1.0 1.0 3.8 1.0 1.0

Sr-89 28.2 8.2 5.0 1.0 1.0 2.7 1.2 1.0

Sr-90 35.9 25.8 15.3 1.2E+07 5.8E+06 9.0 1.6 1.1

Th-228 2.0 1.1 1.0 1.0 1.0 2.0 1.1 1.2–2.9*

Th-229 2.2 1.1 6.0 35.7 25.3 2.0 2.6 2.6

Th-230 62.6 46.7 29.5 4.2 3.5 2.1 26.3 142.6

Th-232 3.9 2.1 3.0 5.2 3.1 2.0 2.6 219.4

Tl-201 2.2 1.0 16.2 1.0 1.0 11.6 1.0 1.0

Tl-202 2.2 1.1 16.6 1.0 1.0 9.3 1.1 1.0

U-233 18.9 150.8 7.7 114.4 104.9 2.0 18.6 88.3

U-234 19.2 112.6 6.2 28.7 23.8 2.0 13.2 131.0

U-235 2.9 4.9 6.8 84.8 224.0 2.0 2.1 1.2

U-238 4.7 14.5 6.2 8.8E+03 3.7E+04 2.0 2.7 2.0

Xe-131m 2.3 1.3 1.0 1.0 1.0 1.0 1.3 1.0

Zn-65 6.2 1.8 12.0 1.0 1.0 7.5 1.6 1.0

* Range represents results from the nine combinations of air exchange rate and room height (see Section 4.7.3).
Final, February 2005 5-5 ISCORS Technical Report 2004-03

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.
ISCORS Technical Report 2004-03 5-6 Final, February 2005

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.
Final, February 2005 6-1 ISCORS Technical Report 2004-03

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, dsrj(t), j = 1 ... J, for every scenario and for

every radionuclide (set at unit specific activity in dry sludge). As shown in Equation 6.1, each 

dsrj(t) has a maximum value, called DSR j ,

DSR j = Max[dsrj

(t)] , (6.1)

and the set of these maximum values, {DSR j }, 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 nonradon 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

(I-131, In-111, Sm-153, Tl-201, and Tl-202), the Nearby Town scenario gave the highest DSRs
ISCORS Technical Report 2004-03 6-2 Final, February 2005

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)

Radionuclide95% Peak

Total DSR

Critical

Pathway(s)

Scaling Factors

1 5 20 50 100

Ac-227 1.06e-02 External 9.67e-01 4.53e+00 1.44e+01 2.39e+01 2.85e+01

Am-241 1.43e-03

Plant and Soil

Ingestion 9.98e-01 4.96e+00 1.95e+01 4.70e+01 8.86e+01

Be-7 1.63e-04 External 8.61e-03 8.68e-03 8.68e-03 8.68e-03 8.68e-03

C-14 2.42e-02

Meat and

Plant

Ingestion 1.00e+00 5.00e+00 2.00e+01 4.99e+01 9.95e+01

Ce-141 1.19e-04 External 4.13e-04 4.13e-04 4.13e-04 4.13e-04 4.13e-04

Co-57 1.03e-03 External 3.91e-01 6.35e-01 6.41e-01 6.41e-01 6.41e-01

Co-60 4.06e-02 External 8.72e-01 3.38e+00 6.38e+00 6.82e+00 6.82e+00

Cr-51 5.26e-05 External 1.06e-04 1.06e-04 1.06e-04 1.06e-04 1.06e-04

Cs-134 2.63e-02 External 7.13e-01 2.02e+00 2.48e+00 2.48e+00 2.48e+00

Cs-137 1.35e-02 External 9.74e-01 4.63e+00 1.54e+01 2.77e+01 3.53e+01

Eu-154 1.88e-02 External 9.23e-01 3.96e+00 9.56e+00 1.17e+01 1.20e+01

Fe-59 3.43e-03 External 3.38e-03 3.39e-03 3.39e-03 3.39e-03 3.39e-03

H-3 1.20e-05 Water 1.00e+00 4.51e+00 1.29e+01 1.41e+01 1.41e+01

I-125 6.09e-04 Meat 1.16e-02 1.17e-02 1.17e-02 1.17e-02 1.17e-02

I-131 2.79e-04 External 1.73e-14 1.73e-14 1.73e-14 1.73e-14 1.73e-14

In-111 1.18e-04 External 0.00e+00 0.00e+00 0.00e+00 0.00e+00 0.00e+00

K-40 2.34e-03 External 8.05e-01 2.73e+00 4.07e+00 4.13e+00 4.13e+00

La-138 1.78e-02 External 7.91e-01 2.59e+00 3.69e+00 3.73e+00 3.73e+00

Np-237 2.42e-01 Fish 1.00e+00 5.00e+00 2.00e+01 5.00e+01 1.00e+02
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)

Radionuclide95% Peak

Total DSR

Critical

Pathway(s)

Scaling Factors

1 5 20 50 100

Pa-231 4.75e-02

Plant

Ingestion and

External 1.00e+00 5.00e+00 2.00e+01 4.94e+01 9.59e+01

Pb-210 1.88e-02 Meat 1.00e+00 4.83e+00 1.56e+01 2.65e+01 3.19e+01

Po-210 6.13e-03 Meat 1.59e-01 1.90e-01 1.90e-01 1.90e-01 0.19

Pu-238 1.23e-03

Plant and Soil

Ingestion 9.91e-01 4.86e+00 1.82e+01 3.99e+01 6.51e+01

Pu-239 1.35e-03

Plant and Soil

Ingestion 9.99e-01 4.98e+00 1.97e+01 4.84e+01 9.36e+01

Ra-226 1.94e-01 Radon * 1.00e+00 5.00e+00 2.00e+01 4.98e+01 9.83e+01

Ra-228 3.55e-02 External 1.00e+00 4.82e+00 1.16e+01 1.30e+01 1.30e+01

Sm-153 9.93e-06 External 0.00e+00 0.00e+00 0.00e+00 0.00e+00 0.00e+00

Sr-89 4.11e-04

Meat and

Plant

Ingestion 6.43e-03 6.47e-03 6.47e-03 6.47e-03 6.47e-03

Sr-90 3.23e-02

Meat and

Plant

Ingestion 9.40e-01 4.17e+00 1.11e+01 1.49e+01 1.56e+01

Th-228 2.36e-02 External * 6.96e-01 1.92e+00 2.29e+00 2.29e+00 2.29e+00

Th-229 5.71e-03 External 1.00e+00 5.00e+00 1.99e+01 4.96e+01 9.85e+01

Th-230 6.24e-02 Radon 1.00e+00 5.01e+00 2.01e+01 5.06e+01 1.03e+02

Th-232 5.28e-02 External 1.00e+00 5.00e+00 2.00e+01 4.99e+01 9.94e+01

Tl-201 1.88e-05 External 0.00e+00 0.00e+00 0.00e+00 0.00e+00 0.00e+00

Tl-202 3.45e-04 External 1.00e-09 1.00e-09 1.00e-09 1.00e-09 1.00e-09

U-233 1.09e-03

Meat and

Plant

Ingestion 9.93e-01 4.89e+00 1.86e+01 4.20e+01 7.25e+01
ISCORS Technical Report 2004-03 6-4 Final, February 2005

Table 6.1 Onsite Resident Scenario Total DSR Results 

(mrem/yr per pCi/g) (continued)

Radionuclide95% Peak

Total DSR

Critical

Pathway(s)

Scaling Factors

1 5 20 50 100

U-234 1.02e-03

Meat and

Plant

Ingestion 9.90e-01 4.86e+00 1.81e+01 3.95e+01 6.42e+01

U-235 2.53e-03 External 9.90e-01 4.86e+00 1.81e+01 3.95e+01 6.39e+01

U-238 1.00e-03 External 9.90e-01 4.86e+00 1.81e+01 3.94e+01 6.35e+01

Xe-131m 2.53e-06 External 7.86e-13 7.86e-13 7.86e-13 7.86e-13 7.86e-13

Zn-65 2.07e-02 External 3.54e-01 5.44e-01 5.47e-01 5.47e-01 5.47e-01

Table 6.2 Onsite Resident Scenario Indoor Radon DSR Results (mrem/yr per

pCi/g)

Radionuclide95% Peak

Non-Rn

DSR

95% Peak Indoor Rn-only DSR

TEDE

(mrem/yr per pCi/g)

WL

(WL per pCi/g)

pCi/L

(pCi/L per pCi/g)

Ra-226 4.91e-02 1.51e-01 6.01e-06 8.72e-04

Th-228 2.14e-02 2.01e-03 4.83e-07 0.0000208

Note: 

The scaling factors in Table 6.1 should be used to correct for the waiting time and multiple years of application.
Final, February 2005 6-5 ISCORS Technical Report 2004-03

Table 6.3 Recreational User Scenario Total DSR Results (mrem/yr per pCi/g)

Radionuclide 95% Peak 

Total DSR

Critical Pathway(s) Scaling Factor*

3 year waiting period

Ac-227 2.35E-03 External 9.06E-01

Am-241 1.82E-04 Soil 9.95E-01

Be-7 4.58E-05 External 6.44E-07

C-14 9.76E-02 Fish 1.00E+00

Ce-141 3.33E-05 External 7.09E-11

Co-57 2.76E-04 External 5.98E-02

Co-60 1.10E-02 External 6.66E-01

Cr-51 1.49E-05 External 1.21E-12

Cs-134 6.41E-03 External 3.63E-01

Cs-137 2.86E-03 External 9.27E-01

Eu-154 5.36E-03 External 7.87E-01

Fe-59 9.67E-04 External 3.87E-08

H-3 4.51E-06 Meat 8.62E-01

I-125 3.33E-05 Meat 1.99E-06

I-131 6.23E-05 External 0.00E+00

In-111 3.30E-05 External 0.00E+00

K-40 7.17E-04 External 6.20E-01

La-138 5.60E-03 External 5.91E-01

Np-237 6.07E-01 Fish 8.55E-01

Pa-231 1.05E-02 External 1.00E+00

Pb-210 8.28E-04 Meat and Soil 9.75E-01

Po-210 4.15E-04 Meat 4.08E-03

Pu-238 1.29E-04 Soil 9.73E-01

Pu-239 1.45E-04 Soil 1.00E+00

Ra-226 8.72E-03 External 1.00E+00

Ra-228 7.37E-03 External 1.00E+00

Sm-153 2.77E-06 External 0.00E+00

Sr-89 1.51E-05 Meat and External 2.74E-07

Sr-90 1.45E-03 Meat 8.64E-01

Th-228 6.51E-03 External 3.37E-01

Th-229 1.52E-03 External 9.99E-01

Th-230 3.05E-03 External 1.00E+00
ISCORS Technical Report 2004-03 6-6 Final, February 2005

Table 6.3 Recreational User Scenario Total DSR Results (mrem/yr per

pCi/g) (continued)

Radionuclide 95% Peak Total

DSR

Critical Pathway(s) Scaling Factor*

3 year waiting period

Th-232 1.24E-02 External 1.00E+00

Tl-201 5.01E-06 External 0.00E+00

Tl-202 9.54E-05 External 1.02E-27

U-233 1.96E-03 Fish 1.00E+00

U-234 1.34E-03 Soil 9.78E-01

U-235 2.15E-03 External 9.79E-01

U-238 1.23E-03 External 9.79E-01

Xe-131m 8.19E-07 External 0.00E+00

Zn-65 2.35E-03 External 4.43E-02

Note:

* Scaling factors calculated to be less than 1e-27 were rounded to zero and listed as 0.00e+00.

Table 6.4 Nearby Town Scenario Total DSR Results (mrem/yr per pCi/g)

Radionuclide95% Peak

Total DSR

Critical

Pathway(s)

Scaling Factors

1 5 20 50 100

Ac-227 5.94e-05 Inhalation 1.00e+00 4.68e+00 1.49e+01 2.51e+01 3.00e+01

Am-241 4.22e-06 Inhalation 1.00e+00 4.98e+00 1.95e+01 4.71e+01 8.89e+01

Be-7 6.43e-12 Inhalation 1.00e+00 1.36e+00 1.36e+00 1.36e+00 1.36e+00

C-14 5.22e-07 Inhalation 1.00e+00 1.00e+00 1.00e+00 1.00e+00 1.00e+00

Ce-141 7.12e-11 Inhalation 1.00e+00 1.01e+00 1.01e+00 1.01e+00 1.01e+00

Co-57 2.98e-10

Meat

Ingestion 1.00e+00 2.74e+00 2.84e+00 2.84e+00 2.84e+00

Co-60 1.36e-08 External 1.00e+00 4.91e+00 1.53e+01 1.93e+01 1.94e+01

Cr-51 1.80e-11

Meat

Ingestion 1.00e+00 1.03e+00 1.03e+00 1.03e+00 1.03e+00

Cs-134 2.84e-08

Meat

Ingestion 1.00e+00 3.67e+00 5.23e+00 5.25e+00 5.25e+00

Cs-137 4.28e-08

Meat

Ingestion and

External 1.00e+00 5.00e+00 1.98e+01 4.65e+01 7.64e+01

Eu-154 7.50e-09 External 1.00e+00 4.97e+00 1.80e+01 3.03e+01 3.28e+01

Fe-59 7.44e-10

Meat

Ingestion 1.00e+00 1.07e+00 1.07e+00 1.07e+00 1.07e+00

H-3 5.32e-07 Inhalation 1.00e+00 1.00e+00 1.00e+00 1.00e+00 1.00e+00
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)

Radionuclide95% Peak

Total DSR

Critical

Pathway(s)

Scaling Factors

1 5 20 50 100

I-125 1.55e-08

Meat

Ingestion 1.00e+00 1.05e+00 1.05e+00 1.05e+00 1.05e+00

I-131 2.12e-08

Meat

Ingestion 1.00e+00 1.00e+00 1.00e+00 1.00e+00 1.00e+00

In-111 4.54e-11

Plant and

Meat

Ingestion 1.00e+00 1.00e+00 1.00e+00 1.00e+00 1.00e+00

K-40 4.94e-10 External 1.00e+00 4.86e+00 1.48e+01 1.88e+01 1.90e+01

La-138 2.69e-08

Inhalation and

External 1.00e+00 3.95e+00 8.23e+00 9.12e+00 9.15e+00

Np-237 5.00e-06 Inhalation 1.00e+00 4.36e+00 1.14e+01 1.47e+01 1.52e+01

Pa-231 5.30e-05 Inhalation 1.00e+00 5.00e+00 2.00e+01 4.95e+01 9.60e+01

Pb-210 4.04e-07 Inhalation 1.00e+00 4.83e+00 1.59e+01 2.75e+01 3.38e+01

Po-210 9.68e-08 Inhalation 1.00e+00 1.35e+00 1.35e+00 1.35e+00 1.35e+00

Pu-238 3.62e-06 Inhalation 1.00e+00 4.91e+00 1.84e+01 4.02e+01 6.59e+01

Pu-239 3.95e-06 Inhalation 1.00e+00 4.99e+00 1.98e+01 4.84e+01 9.38e+01

Ra-226 1.19e-04

Radon

(outdoor) 1.00e+00 4.99e+00 1.99e+01 4.91e+01 9.64e+01

Ra-228 1.96e-04

Radon

(outdoor) 1.00e+00 4.82e+00 1.25e+01 1.43e+01 1.43e+01

Sm-153 7.39e-11

Plant and

Meat

Ingestion 1.00e+00 1.00e+00 1.00e+00 1.00e+00 1.00e+00

Sr-89 5.70e-10

Inhalation and

Meat

Ingestion 1.00e+00 1.03e+00 1.03e+00 1.03e+00 1.03e+00

Sr-90 5.76e-08

Meat

Ingestion 1.00e+00 4.98e+00 1.91e+01 3.75e+01 4.58e+01

Th-228 3.41e-04

Radon

(outdoor) 1.00e+00 2.76e+00 3.29e+00 3.29e+00 3.29e+00

Th-229 1.92e-05 Inhalation 1.00e+00 5.00e+00 1.99e+01 4.97e+01 9.86e+01

Th-230 4.30e-05

Radon

(outdoor) 1.00e+00 5.00e+00 1.99e+01 4.94e+01 9.75e+01

Th-232 3.51e-04

Radon

(outdoor) 1.00e+00 5.00e+00 2.00e+01 4.98e+01 9.93e+01
ISCORS Technical Report 2004-03 6-8 Final, February 2005

Table 6.4 Nearby Town Scenario Total DSR Results (mrem/yr per

pCi/g) (continued)

Radionuclide95% Peak

Total DSR

Critical

Pathway(s)

Scaling Factors

1 5 20 50 100

Tl-201 4.49e-11

Meat

Ingestion 1.00e+00 1.00e+00 1.00e+00 1.00e+00 1.00e+00

Tl-202 2.19e-10

Meat

Ingestion 1.00e+00 1.01e+00 1.01e+00 1.01e+00 1.01e+00

U-233 1.50e-06 Inhalation 1.00e+00 4.92e+00 1.85e+01 4.13e+01 6.97e+01

U-234 1.15e-06 Inhalation 1.00e+00 4.90e+00 1.83e+01 3.98e+01 6.45e+01

U-235 1.19e-06 Inhalation 1.00e+00 4.91e+00 1.84e+01 4.06e+01 6.76e+01

U-238 1.04e-06 Inhalation 1.00e+00 4.90e+00 1.83e+01 3.98e+01 6.44e+01

Xe-131m 0.00e+00 Inhalation 1.00e+00 1.00e+00 1.00e+00 1.00e+00 1.00e+00

Zn-65 5.64e-09

Meat

Ingestion 1.00e+00 2.43e+00 2.48e+00 2.48e+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 95% Peak Total DSR Critical Pathway(s)

Ac-227 4.77e-11 Inhalation

Am-241 3.72e-05 Inhalation

Be-7 0.00e+00 N/A

C-14 4.81e-05 Inhalation

Ce-141 0.00e+00 N/A

Co-57 0.00e+00 N/A

Co-60 2.95e-30 Fish

Cr-51 0.00e+00 N/A

Cs-134 0.00e+00 N/A

Cs-137 2.76e-10 Fish
Table 6.5 Landfill Neighbor Scenario (Municipal Solid Waste) Total DSR

Results (mrem/yr per pCi/g) (continued)

Radionuclide 95% Peak Total DSR Critical Pathway(s)

Final, February 2005 6-9 ISCORS Technical Report 2004-03

Eu-154 2.70e-22 Fish

Fe-59 0.00e+00 N/A

H-3 3.01e-07 Inhalation

I-125 0.00e+00 N/A

I-131 0.00e+00 N/A

In-111 0.00e+00 N/A

K-40 9.19e-06 External

La-138 7.72e-04 Inhalation

Np-237 1.37e-01 Fish and Inhalation

Pa-231 2.44e-04 Inhalation

Pb-210 2.54e-10 Fish

Po-210 0.00e+00 N/A

Pu-238 5.10e-07 Fish and Inhalation

Pu-239 5.58e-05 Fish and Inhalation

Ra-226 1.95e-03 Radon *

Ra-228 5.93e-27 Fish

Sm-153 0.00e+00 N/A

Sr-89 0.00e+00 N/A

Sr-90 3.06e-11 Fish

Th-228 0.00e+00 N/A

Th-229 2.25e-04 Fish and Inhalation

Th-230 8.95e-04 Radon *

Th-232 7.93e-03 Radon *

Tl-201 0.00e+00 N/A

Tl-202 0.00e+00 N/A

U-233 2.46e-05 Fish and Inhalation

U-234 7.32e-06 Radon and Inhalation *

U-235 8.23e-06 Inhalation

U-238 3.71e-06 Inhalation

Xe-131m 0.00e+00 N/A

Zn-65 0.00e+00 N/A
ISCORS Technical Report 2004-03 6-10 Final, February 2005

Table 6.6 Landfill Neighbor Scenario (MSW) Indoor Radon DSR Results

(mrem/yr per pCi/g)

Radionuclide95% Peak

Non-Rn DSR

95% Peak Indoor Rn-only DSR

TEDE(mrem/yr per

pCi/g)

WL

(WL per pCi/g)

pCi/L

(pCi/L per pCi/g)

Ra-226 7.50e-04 3.76e-03 1.48e-07 1.93e-05

Th-230 3.67e-04 1.59e-03 6.25e-08 8.14e-06

Th-232 2.41e-04 3.26e-03 6.47e-07 3.64e-06

U-234 4.61e-06 8.06e-06 3.15e-10 4.11e-08

Table 6.7 Landfill Neighbor Scenario (Surface Impoundment) Total DSR

Results (mrem/yr per pCi/g)

Radionuclide 95% Peak Total DSR Critical Pathway(s)

Ac-227 2.48e-09 Inhalation

Am-241 1.90e-03 Fish

Be-7 0.00e+00 N/A

C-14 6.02e-03 Inhalation

Ce-141 0.00e+00 N/A

Co-57 0.00e+00 N/A

Co-60 1.68e-28 Fish

Cr-51 0.00e+00 N/A

Cs-134 0.00e+00 N/A

Cs-137 1.39e-08 Fish

Eu-154 1.42e-20 Fish

Fe-59 0.00e+00 N/A

H-3 1.66e-05 Inhalation

I-125 0.00e+00 N/A

I-131 0.00e+00 N/A

In-111 0.00e+00 N/A

K-40 4.26e-04 External

La-138 4.45e-02 Inhalation

Np-237 1.18e+01 Water and Plant (Irrigation)

Pa-231 1.04e-02 Inhalation

Pb-210 1.52e-08 Fish

Po-210 0.00e+00 N/A
Table 6.7 Landfill Neighbor Scenario (Surface Impoundment) Total DSR

Results (mrem/yr per pCi/g) (continued)

Radionuclide 95% Peak Total DSR Critical Pathway(s)

Final, February 2005 6-11 ISCORS Technical Report 2004-03

Pu-238 2.52e-06 Fish and Inhalation

Pu-239 2.37e-03 Fish and Inhalation

Ra-226 8.88e-02 Radon *

Ra-228 3.24e-25 Fish

Sm-153 0.00e+00 N/A

Sr-89 0.00e+00 N/A

Sr-90 1.58e-09 Fish

Th-228 0.00e+00 N/A

Th-229 9.45e-03 Fish and Inhalation

Th-230 4.32e-02 Radon *

Th-232 4.06e-01 Radon *

Tl-201 0.00e+00 N/A

Tl-202 0.00e+00 N/A

U-233 9.33e-04 Fish and Inhalation

U-234 3.41e-04 Radon *

U-235 3.36e-04 Inhalation

U-238 1.38e-04 Inhalation

Xe-131m 0.00e+00 N/A

Zn-65 0.00e+00 N/A

Table 6.8 Landfill Neighbor Scenario (Surface Impoundment) Indoor Radon

DSR Results (mrem/yr per pCi/g)

Radionuclide95% Peak

Non-Rn DSR

95% Peak Indoor Rn-only DSR

TEDE

(mrem/yr per pCi/g)

WL

(WL per pCi/g)

pCi/L

(pCi/L per pCi/g)

Ra-226 2.66e-02 1.93e-01 7.57e-06 9.85e-04

Th-230 1.41e-02 8.47e-02 3.32e-06 4.32e-04

Th-232 1.00e-02 1.68e-01 3.33e-05 1.87e-04

U-234 1.99e-04 4.28e-04 1.68e-08 2.19e-06
ISCORS Technical Report 2004-03 6-12 Final, February 2005

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 95% Peak Total DSR Critical Pathway(s)

Ac-227 1.18e+01 Inhalation

Am-241 7.99e-01 Inhalation

Be-7 1.09e-06 External

C-14 3.99e-07 Inhalation

Ce-141 3.02e-06 Inhalation

Co-57 1.02e-04 Meat Ingestion

Co-60 7.97e-03 External

Cr-51 8.78e-07 Meat Ingestion

Cs-134 6.69e-03 Meat Ingestion

Cs-137 1.43e-02 Meat Ingestion and External

Eu-154 4.34e-03 External

Fe-59 3.54e-04 Meat Ingestion

H-3 3.17e-06 Inhalation

I-125 6.99e-02 Meat Ingestion

I-131 1.31e-02 Meat Ingestion

In-111 2.42e-07 Plant and Meat Ingestion

K-40 4.81e-04 External

La-138 1.06e-02 Inhalation and External

Np-237 9.93e-01 Inhalation

Pa-231 2.35e+00 Inhalation

Pb-210 4.74e-02 Inhalation and Plant Ingestion

Po-210 1.64e-02 Inhalation

Pu-238 7.04e-01 Inhalation

Pu-239 7.74e-01 Inhalation

Ra-226 8.80e-02 Inhalation, External, and Plant

Ra-228 2.53e-02 Inhalation

Sm-153 2.03e-07 Plant and Meat Ingestion
Table 6.9 Incinerator Neighbor Scenario Total DSR Results

(mrem/yr per pCi/g) (continued)

Radionuclide 95% Peak Total DSR Critical Pathway(s)

Final, February 2005 6-13 ISCORS Technical Report 2004-03

Sr-89 4.70e-05 Inhalation and Meat Ingestion

Sr-90 3.86e-02 Meat Ingestion

Th-228 5.23e-01 Inhalation

Th-229 3.87e+00 Inhalation

Th-230 5.85e-01 Inhalation

Th-232 2.97e+00 Inhalation

Tl-201 2.31e-07 Meat Ingestion

Tl-202 4.74e-06 Meat Ingestion

U-233 2.43e-01 Inhalation

U-234 2.37e-01 Inhalation

U-235 2.22e-01 Inhalation

U-238 2.12e-01 Inhalation

Xe-131m 0.00e+00 Inhalation

Zn-65 2.28e-03 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)

Radionuclide95% Peak

Total

DSR

Critical

Pathway(s)

Scaling Factors

1 5 20 50 100

Ac-227 7.62e-03 Inhalation 1.00e+00 4.68e+00 1.48e+01 2.47e+01 2.94e+01

Am-241 4.42e-04 Inhalation 1.00e+00 4.98e+00 1.95e+01 4.71e+01 8.88e+01

Be-7 4.00e-05 External 1.00e+00 1.01e+00 1.01e+00 1.01e+00 1.01e+00

C-14 1.71e-07 Inhalation 1.00e+00 1.00e+00 1.00e+00 1.00e+00 1.00e+00

Ce-141 2.60e-05 External 1.00e+00 1.00e+00 1.00e+00 1.00e+00 1.00e+00

Co-57 2.05e-04 External 1.00e+00 1.63e+00 1.64e+00 1.64e+00 1.64e+00
Table 6.10 Sludge Application Worker Scenario Total DSR Results (mrem/yr

per pCi/g) (continued)

Radionuclide95% Peak

Total

DSR

Critical

Pathway(s)

Scaling Factors

1 5 20 50 100

ISCORS Technical Report 2004-03 6-14 Final, February 2005

Co-60 9.87e-03 External 1.00e+00 3.88e+00 7.32e+00 7.82e+00 7.82e+00

Cr-51 1.27e-05 External 1.00e+00 1.00e+00 1.00e+00 1.00e+00 1.00e+00

Cs-134 5.35e-03 External 1.00e+00 2.84e+00 3.47e+00 3.48e+00 3.48e+00

Cs-137 2.25e-03 External 1.00e+00 4.75e+00 1.58e+01 2.84e+01 3.62e+01

Eu-154 4.73e-03 External 1.00e+00 4.29e+00 1.04e+01 1.27e+01 1.30e+01

Fe-59 8.81e-04 External 1.00e+00 1.00e+00 1.00e+00 1.00e+00 1.00e+00

H-3 3.36e-07 Inhalation 1.00e+00 1.00e+00 1.00e+00 1.00e+00 1.00e+00

I-125 2.05e-07 External 1.00e+00 1.01e+00 1.01e+00 1.01e+00 1.01e+00

I-131 4.90e-05 External 1.00e+00 1.00e+00 1.00e+00 1.00e+00 1.00e+00

In-111 2.73e-05 External 1.00e+00 1.00e+00 1.00e+00 1.00e+00 1.00e+00

K-40 6.51e-04 External 1.00e+00 3.39e+00 5.06e+00 5.13e+00 5.13e+00

La-138 5.08e-03 External 1.00e+00 3.28e+00 4.67e+00 4.71e+00 4.71e+00

Np-237 1.17e-03 External 1.00e+00 4.35e+00 1.10e+01 1.40e+01 1.44e+01

Pa-231 6.41e-03 Inhalation 1.00e+00 6.72e+00 4.73e+01 1.78e+02 4.30e+02

Pb-210 2.34e-05 Inhalation 1.00e+00 5.26e+00 1.73e+01 2.94e+01 3.55e+01

Po-210 4.16e-06 Inhalation 1.00e+00 1.19e+00 1.19e+00 1.19e+00 1.19e+00

Pu-238 3.75e-04 Inhalation 1.00e+00 4.91e+00 1.84e+01 4.03e+01 6.57e+01

Pu-239 4.16e-04 Inhalation 1.00e+00 4.99e+00 1.98e+01 4.84e+01 9.37e+01

Ra-226 7.41e-03 External 1.00e+00 4.99e+00 1.99e+01 4.91e+01 9.63e+01

Ra-228 6.74e-03 External 1.00e+00 6.25e+00 1.67e+01 1.88e+01 1.89e+01

Sm-153 1.78e-06 External 1.00e+00 1.00e+00 1.00e+00 1.00e+00 1.00e+00

Sr-89 1.15e-06 External 1.00e+00 1.01e+00 1.01e+00 1.01e+00 1.01e+00

Sr-90 1.67e-05 External 1.00e+00 4.43e+00 1.18e+01 1.58e+01 1.65e+01

Th-228 6.23e-03 External 1.00e+00 2.75e+00 3.29e+00 3.29e+00 3.29e+00

Th-229 3.15e-03 External 1.00e+00 5.00e+00 1.99e+01 4.96e+01 9.85e+01

Th-230 2.63e-03 External 1.00e+00 5.30e+00 2.57e+01 8.61e+01 2.43e+02

Th-232 1.25e-02 External 1.00e+00 1.41e+01 1.63e+02 5.81e+02 1.29e+03

Tl-201 3.28e-06 External 1.00e+00 1.00e+00 1.00e+00 1.00e+00 1.00e+00

Tl-202 8.03e-05 External 1.00e+00 1.00e+00 1.00e+00 1.00e+00 1.00e+00

U-233 1.99e-04 Inhalation 1.00e+00 4.94e+00 1.89e+01 4.37e+01 7.78e+01

U-234 1.23e-04 Inhalation 1.00e+00 4.90e+00 1.83e+01 3.98e+01 6.43e+01
Table 6.10 Sludge Application Worker Scenario Total DSR Results (mrem/yr

per pCi/g) (continued)

Radionuclide95% Peak

Total

DSR

Critical

Pathway(s)

Scaling Factors

1 5 20 50 100

Final, February 2005 6-15 ISCORS Technical Report 2004-03

U-235 6.08e-04 External 1.00e+00 4.90e+00 1.83e+01 3.98e+01 6.45e+01

U-238 1.94e-04 External 1.00e+00 4.90e+00 1.82e+01 3.97e+01 6.41e+01

Xe-131m 4.35e-07 External 1.00e+00 1.00e+00 1.00e+00 1.00e+00 1.00e+00

Zn-65 1.52e-03 External 1.00e+00 1.54e+00 1.55e+00 1.55e+00 1.55e+00

6.5.2 PUBLICLY OWNED TREATMENT WORKS WORKER

SCENARIOS

For the POTW Worker Scenarios, the Loading subscenario 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.
ISCORS Technical Report 2004-03 6-16 Final, February 2005

Table 6.11 POTW Sampling Worker Scenario Total DSR Results (mrem/yr per

pCi/g)

Radionuclide Peak Total DSR Radionuclide Peak Total DSR

Ac-227 3.80e-09 Po-210 8.60e-14

Am-241 4.05e-10 Pu-238 2.63e-11

Be-7 5.08e-10 Pu-239 1.08e-11

C-14 6.03e-10 Ra-226 1.61e-08

Ce-141 7.54e-10 Ra-228 9.19e-09

Co-57 1.17e-09 Sm-153 6.84e-10

Co-60 2.39e-08 Sr-89 8.45e-13

Cr-51 3.23e-10 Sr-90 2.47e-14

Cs-134 1.59e-08 Th-228 1.38e-08

Cs-137 5.79e-09 Th-229 3.42e-09

Eu-154 1.21e-08 Th-230 1.88e-11

Fe-59 1.14e-08 Th-232 1.68e-11

H-3 0.00e+00 Tl-201 9.30e-10

I-125 7.63e-10 Tl-202 4.78e-09

I-131 3.87e-09 U-233 1.74e-11

In-111 4.13e-09 U-234 2.16e-11

K-40 1.45e-09 U-235 1.82e-09

La-138 1.18e-08 U-238 2.54e-10

Np-237 2.49e-09 Xe-131m 2.82e-10

Pa-231 5.61e-10 Zn-65 5.68e-09

Pb-210 5.62e-11

Notes: 

Only External pathway was evaluated in this subscenario. In addition, only deterministic calculations were

performed.
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)

Radionuclide Peak Total DSR Critical Pathway(s)

Ac-227 4.20e-07 External

Am-241 3.84e-08 External

Be-7 5.72e-08 External

C-14 7.13e-08 External

Ce-141 8.57e-08 External

Co-57 1.30e-07 External

Co-60 2.71e-06 External

Cr-51 3.57e-08 External

Cs-134 1.80e-06 External

Cs-137 6.54e-07 External

Eu-154 1.38e-06 External

Fe-59 1.30e-06 External

H-3 0.00e+00 External

I-125 8.15e-08 External

I-131 4.35e-07 External

In-111 4.59e-07 External

K-40 1.65e-07 External

La-138 1.34e-06 External

Np-237 2.67e-07 External

Pa-231 5.34e-08 External

Pb-210 3.78e-09 External

Po-210 9.73e-12 External

Pu-238 1.61e-09 External

Pu-239 6.61e-10 External

Ra-226 3.29e-06 External and Radon *

Ra-228 1.04e-06 External

Sm-153 7.92e-08 External

Sr-89 9.57e-11 External

Sr-90 1.50e-12 External

Th-228 6.74e-05 External *

Th-229 3.76e-07 External

Th-230 1.15e-09 External
ISCORS Technical Report 2004-03 6-18 Final, February 2005

Table 6.12 POTW Intra-POTW Transport Worker Scenario Total DSR Results

(mrem/yr per pCi/g) (continued)

Radionuclide Peak Total DSR Critical Pathway(s)

Th-232 9.37e-10 External

Tl-201 1.04e-07 External

Tl-202 5.39e-07 External

U-233 1.17e-09 External

U-234 1.30e-09 External

U-235 1.91e-07 External

U-238 2.69e-08 External

Xe-131m 3.08e-08 External

Zn-65 6.43e-07 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 Peak Non-Rn DSR Peak Indoor Rn-only DSR

TEDE

(mrem/yr per pCi/g)

WL

(WL per pCi/g)

pCi/L

(PCi/L per pCi/g)

Ra-226 1.83e-06 1.46e-06 3.30e-07 2.00e-04

Th-228 1.57e-06 6.58e-05 7.63e-05 3.87e-02

Note:

Only deterministic calculations were performed for this subscenario.
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)

Radionuclide 95% Peak Total DSR Critical Pathway(s)

Ac-227 4.05E-01 Inhalation

Am-241 2.35E-02 Inhalation

Be-7 1.23E-02 External

C-14 5.60E-07 External

Ce-141 1.25E-02 External

Co-57 1.92E-02 External

Co-60 7.00E-01 External

Cr-51 7.40E-03 External

Cs-134 4.07E-01 External

Cs-137 1.46E-01 External

Eu-154 3.32E-01 External

Fe-59 3.31E-01 External

H-3 1.33E-03 Inhalation

I-125 6.00E-04 External

I-131 9.20E-02 External

In-111 8.05E-02 External

K-40 4.53E-02 External

La-138 3.46E-01 External

Np-237 2.89E-02 Inhalation

Pa-231 8.05E-02 Inhalation and External

Pb-210 1.33E-03 Inhalation and External

Po-210 4.35E-04 Inhalation

Pu-238 1.80E-02 Inhalation

Pu-239 2.38E-02 Inhalation

Ra-226 5.9E-01–2.7E+00* Radon 

Ra-226 5.9E-01–2.7E+00* Radon 

Ra-228 2.59E-01 External

Sm-153 5.80E-03 External

Sr-89 3.95E-04 External

Sr-90 1.05E-03 External

Th-228 2.2E+00–1.8E+01* Radon 

Th-229 1.74E-01 External
ISCORS Technical Report 2004-03 6-20 Final, February 2005

Table 6.14a POTW Biosolids Loading Worker Scenario Total DSR Results

(mrem/yr per pCi/g) (continued)

Th-230 1.68E-02 Inhalation

Th-232 8.35E-02 Inhalation

Tl-201 1.01E-02 External

Tl-202 1.05E-01 External

U-233 7.55E-03 Inhalation

U-234 6.15E-03 Inhalation

U-235 3.68E-02 External

U-238 1.13E-02 External

Xe-131m 8.75E-04 External

Zn-65 1.60E-01 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

95% Peak total DSR (mrem/y per pCi/g)

Air exchange rate

(h-1)

Room height

(m) Ra-226 Th-228

1.5

2 2.7 18

4 1.6 9.4

6 1.2 6.4

3

2 1.2 9.3

4 0.85 4.9

6 0.73 3.4

5

2 0.79 5.6

4 0.64 3.0

6 0.59 2.2
Final, February 2005 6-21 ISCORS Technical Report 2004-03

Table 6.15 POTW Biosolids Loading Worker Scenario Indoor Radon DSR Results

(mrem.yr per pCi/g)

Radio-nuclide 95% Peak

Non-Rn DSR

95% Peak Indoor Rn-only DSR*

TEDE

(mrem/yr per pCi/g)

WL

(WL per pCi/g)

pCi/L

(pCi/yr per pCi/g)

Ra-226 0.48 0.10–2.2 2.3E-5 – 5.0E-4 0.026 – 0.32

Th-228 0.45 1.7–18 1.9E-3 – 2.0E-2 2.5 – 11

Note:

* Range represents results from the nine combinations of air exchange rate and room height (see Section 4.7.3).

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

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,

Ds = Ar × DSR rs , r

∑ (7.1)

where {DSR rs} 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.
ISCORS Technical Report 2004-03 7-2 Final, February 2005

Table 7.1 Calculated Total Peak Dose (Total Effective Dose Equivalent–TEDE)

from Survey Samples: Summary Results With and Without Indoor

Radon Contribution

Scenario Subscenario Median sample 95% sample Dominant

Radionuclide(s)

[pathways] TEDE TEDE

w/o Rn

TEDE TEDE

w/o Rn

S1 - Onsite

Resident

1 yr of appl. 0.5 0.2 3 1 Ra-226 [indoor radon]

5 2.5 1 14 4.9 Ra-226 [indoor radon]

20 9.2 3.4 55 16 Ra-226 [indoor radon]

50 22 7.2 130 37 Ra-226 [indoor radon]

100 42 13 260 69 Ra-226 [indoor radon]

S2 - Recreational N/A 0.04 -- 0.22 -- Ra-226 [external]

S3 - Nearby Town 1 yr of appl. 6.4e-04 -- 3.2e-03 -- Ra-226 [outdoor radon]

5 2.8e-03 -- 0.014 -- Ra-226 [outdoor radon]

20 8.5e-03 -- 0.045 -- Ra-226 [outdoor radon]

50 0.017 -- 0.094 -- Ra-226 [outdoor radon]

100 0.029 -- 0.17 -- Ra-226 [outdoor radon]

S4 - Landfill MSW - Sludge 4.6e-03 1.6e-03 0.027 0.01 Ra-226 [indoor radon]

MSW - Ash 0.014 3.1e-03 0.041 0.014 Ra-226 [indoor radon]

Impoundment 0.21 0.062 1.2 0.36 Ra-226 [indoor radon]

S5 - Incinerator N/A 1.2 -- 7.7 -- multiple [multiple]

S6 - Sludge

Application

Worker

1 yr of appl. 0.032 -- 0.15 -- Ra-226 [external]

5 0.16 -- 0.77 -- Ra-226 [external]

20 0.57 -- 3 -- Ra-226 [external]

50 1.3 -- 7.4 -- Ra-226 [external]

100 2.3 -- 15 -- Ra-226 [external]

S7 - POTW

Workers

Sampling

(mrem/sample)

9.6e-08 -- 4.9e-07 -- Ra-226 [external]

Transport (mrem/hr) 4.6e-05 1.1e-05 1.9e-04 5.6e-05 Th-228 [indoor radon,

external]

Loading 3.8–17 2 2.7 17–702 13 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).
Final, February 2005 7-3 ISCORS Technical Report 2004-03

Table 7.2 Calculated Total Peak Radon Doses and Concentrations from Survey

Samples

Scenario Subscenario Median sample 95% sample

TEDE

Rn only

WL Rn

only

pCi/L

Rn-222

pCi/L

Rn-220

TEDE

Rn only

WL Rn

only

pCi/L

Rn-222

pCi/L

Rn-220

S1 - Onsite

Resident

1 yr of appl. 0.3 1.3e-05 1.7e-03 8.3e-08 2 7.9e-05 0.011 4.0e-07

5 1.5 6.2e-05 8.7e-03 2.3e-07 9.8 3.9e-04 0.057 1.1e-06

20 6 2.4e-04 0.035 2.7e-07 39 1.6e-03 0.23 1.3e-06

50 15 6.0e-04 0.087 2.7e-07 98 3.9e-03 0.56 1.3e-06

100 30 1.2e-03 0.17 2.7e-07 193 7.7e-03 1.1 1.3e-06

S4 - Landfill MSW - Sludge 9.1e-03 3.4e-07 3.9e-05 0 0.057 2.1e-06 2.6e-04 1.5e-06

MSW - Ash 0.018 1.0e-06 7.2e-05 1.8e-06 0.078 3.1e-06 3.5e-04 3.4e-06

Impoundment 0.47 2.5e-05 2.0e-03 0 2.9 1.5e-04 0.013 7.5e-05

S7 - POTW

Workers

Transport 3.4e-05 3.4e-05 4.0e-04 0.017 1.5e-04 1.6e-04 2.6e-03 0.081

Loading 92 0.028 3 10 390 0.12 19 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. 
ISCORS Technical Report 2004-03 7-4 Final, February 2005

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, I-125, I-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. 
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 8x = 4 per hour, rsludge = 1 g/cm3

, Asludge = 6900 m2, Vsludge = 13,800 m3, Vroom = 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

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 Asludge × (texp /1000 hours)/[ (0.008 + 8x) × 

(2.69 hroom

– 0.77 + 8x) Vroom] ,

(7.2)

DSRTh-228 . 0.45 + 2649 rsludge Asludge × (texp /1000 hours)/[ (45 + 8x) × 

(1.25 hroom

– 0.77 + 8x) Vroom] ,

(7.3)

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 8x is the room air exchange rate in exchanges per hour; rsludge the bulk density of the sludge

in grams per cubic cm; Vsludge the total volume of sludge in the room in cubic meters; Vroom the

total volume of the room in cubic meters; hroom the height of the room in meters; Asludge 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
ISCORS Technical Report 2004-03 7-6 Final, February 2005

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 Subscenario

Source Variability: 

Ratio of 95% survey

dose to 5% survey dose,

both using 95% DSRs

Parameter Uncertainty &

Variability: 

Ratio of 95% survey dose

using 95% DSRs to 95%

survey dose using 5% DSRs

Onsite

Resident

1 yr of appl. 43 1.3

5 46 1.3

20 58 1.2

50 87 1.2

100 100 1.2

Recreational

User

N/A 31 1.5

Residents of

Nearby Town

1 yr of appl. 21 1.08

5 25 1.09

20 32 1.08

50 40 1.03

100 59 1.04

Landfill

Neighbor

MSW (Sludge) 130 1.6

MSW (Ash) 10 1.7

Impoundment 130 1.4

POTW

Incinerator

Neighbor

50-year 

operational life

36 2.3
Final, February 2005 7-7 ISCORS Technical Report 2004-03

Table 7.3 Source Variability and Parameter Variability and Uncertainty in

Calculated Survey Sample Doses (continued)

Sludge

Application

Worker

1 yr of appl. 22 1.09

5 24 1.07

20 36 1.2

50 60 1.3

100 94 1.3

POTW

Workers

Sampling 22 –

Transport 14 –

Loading 16–19* 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).

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

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:

C 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.

C 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.

C In specific cases of very high levels of radioactive materials (e.g., levels above the 95%),

there is the potential for localized radiation exposure.
ISCORS Technical Report 2004-03 8-2 Final, February 2005

C 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:

C The exposure scenarios are somewhat conservative; in addition, the doses mentioned above

are upper-end percentile values.

C 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.

C 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. 
Final, February 2005 9-1 ISCORS Technical Report 2004-03

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.
ISCORS Technical Report 2004-03 9-2 Final, February 2005

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

<http://www.ngpc.state.ne.us/wildlife/wtdeer.html>.

NRC Till, J.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.
Final, February 2005 9-3 ISCORS Technical Report 2004-03

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, Subpart Z. 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.

Appendix A

Baseline Parameter Values and

Distributions

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-1 ISCORS Technical Report 2004-03

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 doseto-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.
ISCORS Technical Report 2004-03 A-2 Final, February 2005

Table A.1 Baseline Values and Distributions for the Kd Parameter

Element of

Interest

RESRAD 6.0

Default

Value

Baseline

Value as

Geometric

Mean of the

Distribution 

Distribution from NUREG/CR-6697

Truncated Lognormal-n Distribution Parameters**

 ) exp()

Ac 20 825 6.72 3.22 825

Am 20 1445 7.28 3.15 1445

Ba 50 560 6.33 3.22 560

Be 929 929 6.84 3.22 929

Bi 0 105 4.65 3.22 105

C 0 11 2.40 3.22 11

Ce 1000 1998 7.6 2.08 1998

Co 1000 235 5.46 2.53 235

Cr 103 103 4.63 2.76 103

Cs 1000 446 6.10 2.33 446

Eu 825* 825 6.72 3.22 825

Fe 1000 209 5.34 2.67 209

H 0 0.06 -2.81 .5 .06

I 0.1 4.6 1.52 2.19 4.6

In 158 158 5.07 3.22 158

K 5.5 5.5 1.7 0.49 5.5

La 4.98 4.98 1.61 3.22 4.98

Np 257* 17 2.84 2.25 17

Pa 50 380 5.94 3.22 380

Pb 100 2392 7.78 2.76 2392

Po 10 181 5.20 1.68 181

Pu 2000 953 6.86 1.89 953

Ra 70 3533 8.17 1.70 3533

Sm 825* 825 6.72 3.22 825

Sr 30 32 3.45 2.12 32

Th 60,000 5884 8.68 3.62 5884

Tl 0 71 4.26 3.22 71

U 50 126 4.84 3.13 126

Zn 0 1075 6.98 4.44 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.
Final, February 2005 A-3 ISCORS Technical Report 2004-03

Table A.2 Baseline Values and Distributions for the Plant Transfer Factor

Element of

Interest

RESRAD 6.0

Default Value

Baseline

Value as

Geometric

Mean of the

Distribution

Distribution from NUREG/CR-6697

Truncated Lognormal-n Distribution Parameters*

 ) exp()

Ac 2.5 × 10-3 1.0 × 10-3 -6.91 1.1 1.0 × 10-3

Am 1.0 × 10-3 1.0 × 10-3 -6.91 0.9 1.0 × 10-3

Ba 5.0 × 10-3 1.0 × 10-2 -4.61 1.1 1.0 × 10-2

Be 4.0 × 10-3 4.0 × 10-3 -5.52 1.1 4.0 × 10-3

Bi 1.0 × 10-1 1.0 × 10-1 -2.30 1.1 1.0 × 10-1

C 5.5 7.0 × 10-1 -0.36 0.9 7.0 × 10-1

Ce 2.0 × 10-3 2.0 × 10-3 -6.21 1.0 2.0 × 10-3

Co 8.0 × 10-2 8.0 × 10-2 -2.53 0.9 8.0 × 10-2

Cr 2.5 × 10-4 1.0 × 10-2 -4.61 1.0 1.0 × 10-2

Cs 4.0 × 10-2 4.0 × 10-2 -3.22 1.0 4.0 × 10-2

Eu 2.5 × 10-3 2.0 × 10-3 -6.21 1.1 2.0 × 10-3

Fe 1.0 × 10-3 1.0 × 10-3 -6.91 0.9 1.0 × 10-3

H 4.8 4.8 1.57 1.1 4.8

I 2.0 × 10-2 2.0 × 10-2 -3.91 0.9 2.0 × 10-2

In 3.0 × 10-3 3.0 × 10-3 -5.81 1.1 3.0 × 10-3

K 3.0 × 10-1 3.0 × 10-1 -1.20 1.1 3.0 × 10-1

La 2.5 × 10-3 2.0 × 10-3 -6.21 0.9 2.0 × 10-3

Np 2.0 × 10-2 2.0 × 10-2 -3.91 0.9 2.0 × 10-2

Pa 1.0 × 10-2 1.0 × 10-2 -4.61 1.1 1.0 × 10-2

Pb 1.0 × 10-2 4.0 × 10-3 -5.52 0.9 4.0 × 10-3

Po 1.0 × 10-3 1.0 × 10-3 -6.9 0.9 1.0 × 10-3

Pu 1.0 × 10-3 1.0 × 10-3 -6.91 0.9 1.0 × 10-3

Ra 4.0 × 10-2 4.0 × 10-2 -3.22 0.9 4.0 × 10-2

Sm 2.5 × 10-3 2.0 × 10-3 -6.21 1.1 2.0 × 10-3

Sr 3.0 × 10-1 3.0 × 10-1 -1.20 1.0 3.0 × 10-1

Th 1.0 × 10-3 1.0 × 10-3 -6.91 0.9 1.0 × 10-3

Tl 2.0 × 10-1 2.0 × 10-1 -1.61 1.1 2.0 × 10-1

U 2.5 × 10-3 2.0 × 10-3 -6.21 0.9 2.0 × 10-3

Zn 4.0 × 10-1 4.0 × 10-1 -0.92 0.9 4.0 × 10-1

* 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.3 Baseline Values and Distribution for the Meat Transfer Factor

Element of

Interest

 RESRAD 6.0

Default Value

Baseline

Value as

Geometric 

Mean of the

Distribution

Distribution from NUREG/CR-6697

Truncated Lognormal-n Distribution Parameters*

 ) exp()

Ac 2.0 × 10-5 2.0 × 10-5 -10.82 1.0 2.0 × 10-5

Am 5.0 × 10-5 5.0 × 10-5 -9.90 0.2 5.0 × 10-5

Ba 2.0 × 10-4 2.0 × 10-4 -8.52 0.9 2.0 × 10-4

Be 1.0 × 10-3 5.0 × 10-3 -5.30 1.0 5.0 × 10-3

Bi 2.0 × 10-3 2.0 × 10-3 -6.21 1.0 2.0 × 10-3

C 3.1 × 10-2 3.0 × 10-2 -3.47 1.0 3.0 × 10-2

Ce 2.0 × 10-5 2.0 × 10-5 -10.82 0.9 2.0 × 10-5

Co 2.0 × 10-2 3.0 × 10-2 -3.51 1.0 3.0 × 10-2

Cr 9.0 × 10-3 3.0 × 10-2 -3.51 0.4 3.0 × 10-2

Cs 3.0 × 10-2 5.0 × 10-2 -3.00 0.4 5.0 × 10-2

Eu 2.0 × 10-3 2.0 × 10-3 -6.21 1.0 2.0 × 10-3

Fe 2.0 × 10-2 3.0 × 10-2 -3.51 0.4 3.0 × 10-2

H 1.2 × 10-2 1.2 × 10-2 -4.42 1.0 1.2 × 10-2

I 7.0 × 10-3 4.0 × 10-2 -3.22 0.4 4.0 × 10-2

In 4.0 × 10-3 4.0 × 10-3 -5.52 1.0 4.0 × 10-3

K 2.0 × 10-2 2.0 × 10-2 -3.91 0.2 2.0 × 10-2

La 2.0 × 10-3 2.0 × 10-3 -6.21 1.0 2.0 × 10-3

Np 1.0 × 10-3 1.0 × 10-3 -6.91 0.7 1.0 × 10-3

Pa 5.0 × 10-3 5.0 × 10-6 -12.21 1.0 5.0 × 10-6

Pb 8.0 × 10-4 8.0 × 10-4 -7.13 0.7 8.0 × 10-4

Po 5.0 × 10-3 5.0 × 10-3 -5.30 0.7 5.0 × 10-3

Pu 1.0 × 10-4 1.0 × 10-4 -9.21 0.2 1.0 × 10-4

Ra 1.0 × 10-3 1.0 × 10-3 -6.91 0.7 1.0 × 10-3

Sm 2.0 × 10-3 2.0 × 10-3 -6.21 1.0 2.0 × 10-3

Sr 8.0 × 10-3 1.0 × 10-2 -4.61 0.4 1.0 × 10-2

Th 1.0 × 10-4 1.0 × 10-4 -9.21 1.0 1.0 × 10-4

Tl 2.0 × 10-2 2.0 × 10-2 -3.91 1.0 2.0 × 10-2

U 3.4 × 10-4 8.0 × 10-4 -7.13 0.7 8.0 × 10-4

Zn 1.0 × 10-1 1.0 × 10-1 -2.30 0.3 1.0 × 10-1

* 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.4 Baseline Values and Distributions for the Milk Transfer Factor 

Element of

Interest

RESRAD 6.0

Default Value

Baseline

Value as

Geometric 

Mean of the

Distribution

Distribution from NUREG/CR-6697

Truncated Lognormal-n Distribution Parameters*

 ) exp()

Ac 2.0 × 10-5 2.0 × 10-6 -13.12 0.9 2.0 × 10-6

Am 2.0 × 10-6 2.0 × 10-6 -13.12 0.7 2.0 × 10-6

Ba 5.0 × 10-4 5.0 × 10-4 -7.60 0.7 5.0 × 10-4

Be 2.0 × 10-6 2.0 × 10-6 -13.12 0.9 2.0 × 10-6

Bi 5.0 × 10-4 1.0 × 10-3 -6.91 0.9 1.0 × 10-3

C 1.2 × 10-2 1.2 × 10-2 -4.4 0.9 1.2 × 10-2

Ce 3.0 × 10-5 3.0 × 10-5 -10.41 0.7 3.0 × 10-5

Co 2.0 × 10-3 2.0 × 10-3 -6.21 0.7 2.0 × 10-3

Cr 2.0 × 10-3 2.0 × 10-3 -6.21 0.7 2.0 × 10-3

Cs 8.0 × 10-3 1.0 × 10-2 -4.61 0.5 1.0 × 10-2

Eu 2.0 × 10-5 6.0 × 10-5 -9.72 0.9 6.0 × 10-5

Fe 3.0 × 10-4 3.0 × 10-4 -8.11 0.7 3.0 × 10-4

H 1.0 × 10-2 1.0 × 10-2 -4.6 0.9 1.0 × 10-2

I 1.0 × 10-2 1.0 × 10-2 -4.61 0.5 1.0 × 10-2

In 2.0 × 10-4 2.0 × 10-4 -8.52 0.9 2.0 × 10-4

K 7.0 × 10-3 7.0 × 10-3 -4.96 0.5 7.0 × 10-3

La 2.0 × 10-5 6.0 × 10-5 -9.72 0.9 6.0 × 10-5

Np 5.0 × 10-6 1.0 × 10-5 -11.51 0.7 1.0 × 10-5

Pa 5.0 × 10-6 5.0 × 10-6 -12.21 0.9 5.0 × 10-6

Pb 3.0 × 10-4 3.0 × 10-4 -8.11 0.9 3.0 × 10-4

Po 3.4 × 10-4 4.0 × 10-4 -7.82 0.7 4.0 × 10-4

Pu 1.0 × 10-6 1.0 × 10-6 -13.82 0.5 1.0 × 10-6

Ra 1.0 × 10-3 1.0 × 10-3 -6.91 0.5 1.0 × 10-3

Sm 2.0 × 10-5 6.0 × 10-5 -9.72 0.9 6.0 × 10-5

Sr 2.0 × 10-3 2.0 × 10-3 -6.21 0.5 2.0 × 10-3

Th 5.0 × 10-6 5.0 × 10-6 -12.21 0.9 5.0 × 10-6

Tl 3.0 × 10-3 3.0 × 10-3 -5.81 0.9 3.0 × 10-3

U 6.0 × 10-4 4.0 × 10-4 -7.82 0.6 4.0 × 10-4

Zn 1.0 × 10-2 1.0 × 10-2 -4.61 0.9 1.0 × 10-2

* Distribution is truncated at a lower quantile of 0.001 and an upper quantile of 0.999.
ISCORS Technical Report 2004-03 A-6 Final, February 2005

Table A.5 Baseline Values and Distributions for the Aquatic Food (Fish)

Transfer Factor

Element of

Interest

RESRAD 6.0

Default Value

Baseline

Value as

Geometric 

Mean of the

Distribution

Disbribution from NUREG/CR-6697

Lognormal Distribution Parameters 

 ) exp()

Ac 15 15 2.7 1.1 15

Am 30 30 3.4 1.1 30

Ba 4.0 4.0 1.4 1.1 4.0

Be 100 100 4.6 1.1 100

Bi 15 15 2.7 1.1 15

C 50000 49000 10.8 1.1 49000

Ce 30 30 3.4 1.1 30

Co 300 300 5.7 1.1 300

Cr 200 200 5.3 1.1 200

Cs 2000 2000 7.6 0.7 2000

Eu 50 50 3.9 1.1 50

Fe 200 200 5.3 1.1 200

H 1 1 0 0.1 1

I 40 40 3.7 1.1 40

In 10000 10000 9.2 1.1 10000

K 1000 1000 6.9 1.1 1000

La 30 30 3.4 1.1 30

Np 30 30 3.4 1.1 30

Pa 10 10 2.3 1.1 10

Pb 300 300 5.7 1.1 300

Po 100 100 4.6 1.1 100

Pu 30 30 3.4 1.1 30

Ra 50 50 3.9 1.1 50

Sm 25 25 3.2 1.1 25

Sr 60 60 4.1 1.1 60

Th 100 100 4.6 1.1 100

Tl 10,000 10,000 9.2 1.1 10,000

U 10 10 2.3 1.1 10

Zn 1000 1000 6.9 1.1 1000
Final, February 2005 A-7 ISCORS Technical Report 2004-03

A.3 Code-Specific Parameters

Table A.6 Probability Distribution Notations Used in Baseline Parameter Tables

Notation Type of Distribution

TruncN(, ), a, b) Truncated Normal

TruncLogN(, ), a, b) Truncated Lognormal

BoundedLogN(, ), a, b) Bounded Lognormal

Uniform(a, b) Uniform

LogU(a, b) Loguniform

Triangular(a, c, b) Triangular

Continuous Linear Empirical

Continuous Log 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-Offsite default value not used as baseline value.

N/A Not applicable.
ISCORS Technical Report 2004-03 A-8 Final, February 2005 Table A.7

RESRAD Baseline Parameter V

alues 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) 

Commen

Values/D

TitleTitle Scenario

dependent

Scenario Definition

Dose Factor Library Default File RESRAD Default LCut-off Half Life (180 d or 30 d) (180 d) 30 dGraphics ParametersNumber of Points (32, 64, 128, 256,512, 1024)

32

Linear Spacing/Log Spacing Log SpacingTime Integration ParametersMaximum No of Points for Dose 17Maximum No of Points for Risk (257) 1 Radiation dose inste

concerned in the anaintegration point wiltime.

User PreferencesUse Line Draw Character (yes/no) yesFind Peak Pathway Dose (yes/no) yes
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) 

Commen

Values/D

Final, February 2005 A-9 ISCORS Technical Report 2004-03 Save All Files After Each Run (yes/no) no yes Time Integrated Probabilistic Risk (yes/no) no Calculation Times Basic Radiation Dose Limit (mrem/year) 25 Times for Calculation (years) (1000) 1023 Values used to obtai

year. Source Nuclide Concentration (pCi/g) (100) 0.0044 Scenario definition. density of 1.52 g/cm

Contaminated Zone Parameters Area of Contaminated Zone (m2) (10000) 404685 Scenario definition (

meter). Thickness of Contaminated Zone (m) (2) 0.15 Scenario definition (contamination) Length Parallel to Aquifer Flow (m) (100) 636 Scenario definition (
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) 

Commen

Values/D

ISCORS Technical Report 2004-03 A-10 Final, February 2005 Cover & Contaminated Zone Hydrological Data Cover Depth (m) 0 Scenario Definition 

assumed) Density of Cover Material (g/cm3) 1.5 Not required when c

Cover Erosion Rate (m/yr) 0.001 Not required when c

Density of Contaminated Zone (g/cm3) (1.5) 1.52* Contaminated Zone Erosion Rate (m/yr) (0.001) 0 0 was used in dose a

conservative results. Contaminated Zone Total Porosity (0.4) 0.426 Values was calculatecontaminated zone. Contaminated Zone Field Capacity 0.2 Contaminated Zone Hydraulic Conductivity (m/yr) (10) 9.974** BoundedLogN(2.3, 2.11, 0.004, 9250) Contaminated Zone b Parameter (5.3) 2.895** BoundedLogN(1.06, 0.66, 0.5, 30) Humidity in Air (g/m3) (8) 7.243** TruncLogN(1.98, 0.334, 0.001, 0.999) Evapotranspiration Coefficient (0.5) 0.625* Uniform(0.5, 0.75)
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) 

Commen

Values/D

Final, February 2005 A-11 ISCORS Technical Report 2004-03 Wind Speed (m/s) (2) 4.242** BoundedLogN(1.445, 0.2419, 1.4, 13) Precipitation (m/yr) 1.0 Irrigation (m/yr) 0.2 Irrigation mode (Overhead/Ditch) Overhead Runoff Coefficient (0.2) 0.45* Uniform(0.1, 0.8) Watershed Area for Nearby Stream or Pond (m2) 1000000 Accuracy for Water/Soil Computation 0.001 Saturated Zone Hydrological Data Density (g/cm3) (1.5) 1.52* TruncN(1.52, 0.230, 0.001, 0.999) Effective Porosity (0.2) 0.355* TruncN(0.355, 0.0906, 0.001, 0.999) Total Porosity (0.4) 0.425* TruncN(0.425, 0.0867, 0.001, 0.999) Field Capacity 0.2 Hydraulic Conductivity (m/yr) (100) 9.974** BoundedLogN(2.3, 2.11, 0.004, 9250)
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) 

Commen

Values/D

ISCORS Technical Report 2004-03 A-12 Final, February 2005 b Parameter (5.3) Not required when th

was set to 0. Hydraulic Gradient (0.02) 0.00604** BoundedLogN(-5.11, 1.77, 7e-5, 0.5) Water Table Drop Rate (m/yr) (0.001) 0 0 was used to get co

Well Pump Intake Depth (m below water table) (10) 15.33* Triangular(6, 10, 30) Model for Water Transportation (Nondispersion/Mass-Balance) Nondispersion Well Pumping Rate (m3/yr) 250 Unsaturated Zone Parameters Thickness (m) (4) 9.895** BoundedLogN(2.2926, 1.276, 0.18, 320) Density (g/cm3) (1.5) 1.52* TruncN(1.52, 0.230, 0.001, 0.999) Effective Porosity (0.2) 0.355* TruncN(0.355, 0.0906, 0.001, 0.999) Total Porosity (0.4) 0.425* TruncN(0.425, 0.0867, 0.001, 0.999) Field Capacity 0.2
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) 

Commen

Values/D

Final, February 2005 A-13 ISCORS Technical Report 2004-03 Hydraulic Conductivity (m/yr) (10) 9.974** BoundedLogN(2.3, 2.11, 0.004, 9250) b Parameter (5.3) 2.895** BoundedLogN(1.06, 0.66, 0.5, 30) Occupancy, Inhalation and External Gamma Data Inhalation Rate (m3/yr) (8400) 8627* Triangular(4380, 8400, 13100) Mass Loading for Inhalation (g/m3) (0.001) 2.45E-05* Continuous Linear Exposure Duration (y) 30 Indoor Dust Filtration Factor (0.4) 0.55* Uniform(0.15, 0.95) External Gamma Shielding Factor (0.7) 0.27** BoundedLogN(-1.3, 0.59, 0.044, 1) Indoor Time Fraction (0.5) 0.651* Outdoor Time Fraction 0.25 Shape of Contaminated Zone (circular/noncircular) circular Ingestion Pathway Dietary Data Fruit, Vegetable and Grain Consumption (kg/yr) (160) 210.33* Triangular(135, 178, 318)
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) 

Commen

Values/D

ISCORS Technical Report 2004-03 A-14 Final, February 2005 Leafy Vegetable Consumption (kg/yr) (14) 22.667* No distribution / Triangular (13, 25, 30) Baseline distribution 

using methodology o

Milk (L/yr) (92) 120.67* Triangular (60, 102, 200) Meat and Poultry (kg/yr) (63) 222.1* No distribution / Triangular (5.0, 72.6, 588.7) Baseline distribution 

using methodology o

Fish (kg/yr) (5.4) 155.6* No distribution / Triangular (2.0, 56.3, 408.5) Baseline distribution 

using methodology o

Other Sea Food (kg/yr) (0.9) 0 No ocean fish. Soil Ingestion (g/yr) (36.5) 18.27* Triangular (0, 18.3, 36.5) Drinking Water Intake (L/yr) (510) 409.5** TruncLogN(6.015, 0.489, 0.001, 0.999) Contaminated Fractions Drinking Water (1) 0.9 Scenario definition. Household Water 1 Livestock water 1 Irrigation water 1
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) 

Commen

Values/D

Final, February 2005 A-15 ISCORS Technical Report 2004-03 Aquatic food (0.5) 0.463* Triangular(0, 0.39, 1) Plant food -1 Calculated by RESR

Meat -1 Calculated by RESRMilk -1 Calculated by RESRIngestion Pathway, Non-dietary Data Livestock fodder intake for meat (kg/d) 68 Livestock fodder intake for milk (kg/d) 55 Livestock water intake for meat (L/d) 50 Livestock water intake for milk (L/d) 160 Livestock intake of soil (kg/d) 0.5 Mass loading for foliar deposition (g/m3) 0.0001 Depth of soil mixing layer (m) (0.15) 0.25* Triangular(0.0, 0.15, 0.6) Depth of roots (m) (0.9) 2.15* Uniform(0.3, 4.0)
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) 

Commen

Values/D

ISCORS Technical Report 2004-03 A-16 Final, February 2005 Groundwater Fractional Usage Drinking Water 1 Household Water 1 Livestock water (1) 0.5 To consider potentia

contamination as we

Irrigation water (1) 0.5 To consider potentia

contamination as we

Non-leafy Plant Factors Wet Weight Crop Yield (kg/m2) (0.7) 1.75** TruncLogN(0.56, 0.48, 0.001, 0.999) Length of Growing Season (y) 0.17 Translocation Factor 0.1 Weathering Removal Constant (1/yr) (20) 35.70* Triangular(5.1, 18, 84) Wet Foliar Interception Fraction 0.25 Dry Foliar Interception Fraction 0.25 Leafy Plant Factors Wet Weight Crop Yield (kg/m2) 1.5 Length of Growing Season (y) 0.25
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) 

Commen

Values/D

Final, February 2005 A-17 ISCORS Technical Report 2004-03 Translocation Factor 1 Wet Foliar Interception Fraction (0.25) 0.560* Triangular(0.06, 0.67, 0.95) Dry Foliar Interception Fraction 0.25 Fodder Plant Factors Wet Weight Crop Yield (kg/m2) 1.1 Length of Growing Season (y) 0.08 Translocation Factor 1 Wet Foliar Interception Fraction 0.25 Dry Foliar Interception Fraction 0.25 Radon Data Cover Total Porosity 0.4 N/A No cover. Cover Volumetric Water Content 0.05 N/A No cover. Cover Radon Diffusion Coefficient (m2/s) 2 x 10-6 N/A No cover. Bldg Foundation Thickness (m) 0.15 Bldg Foundation Density (g/cm3) 2.4
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) 

Commen

Values/D

ISCORS Technical Report 2004-03 A-18 Final, February 2005 Bldg Foundation Total Porosity 0.1 Bldg Foundation Volumetric Water Content 0.03 Bldg Foundation Radon Diffusion Coefficient (m2/s) 3 x 10-7 Contaminated Radon Diffusion Coefficient (m2/s) 2 x 10-6 Radon Vertical Dimension of Mixing (m) 2 Building Air Exchange Rate (1/hr) 0.5 Building Room Height (m) 2.5 Building Indoor Area Factor 0 Value calculated by 

Foundation Depth Below Ground Surface (m) -1 Value calculated by Rn-222 Emanation Coefficient 0.25 Rn-220 Emanation Coefficient 0.15
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) 

Commen

Values/D

Final, February 2005 A-19 ISCORS Technical Report 2004-03 Storage Times Before Use Data Fruits, Non-leafy Vegetables and Grain (d) 14 Leafy Vegetables (d) 1 Milk (d) 1 Meat (d) 20 Fish (d) 7 Crustacea and Molusks (d) 7 Well Water (d) 1 Surface Water (d) 1 Livestock Fodder (d) 45 Carbon-14 Data C-12 Concentration in Local Water 0.00002 C-12 Concentration in Contaminated Soil 0.03 Fraction of Vegetation Carbon Adsorbed from Soil 0.02
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) 

Commen

Values/D

ISCORS Technical Report 2004-03 A-20 Final, February 2005 Fraction of Vegetation Carbon Adsorbed from Air 0.98 Thickness of Evasion Layer of C-14 in Soil 0.3 0.367* Triangular(0.2, 0.3, 0.6) C-14 Evasion Flux Rate from Soil 0.0000007 C-12 Evasion Flux Rate from Soil 1E-10 Grain Fraction in Livestock Feed (Balance is Hay/Fodder) for Beef Cattle 0.8 Grain Fraction in Livestock Feed (Balance is Hay/Fodder) for Milk Cow 0.2 DCF Correction Factor for Gaseous Forms of C-14 88.94
Final, February 2005 A-21 ISCORS Technical Report 2004-03 Table A.8 RESRAD Baseline Parameter Correlations for Probabilistic Analyses Parameter 1 Parameter 2 Correlation Coefficient Comments Unsaturated Zone Soil Density Unsaturated Zone Total Porosity -0.99 The two parameters are s

correlated. Saturated Zone Soil Density Saturated Zone Total Porosity -0.99 The two parameters are scorrelated. Unsaturated Zone Total Porosity Unsaturated Zone Effective Porosity 0.96 A correlation of 0.96 propairing of sampling data

Saturated Zone Total Porosity Saturated Zone Effective Porosity 0.96 A correlation of 0.96 pro

pairing of sampling data

Unsaturated Zone Soil Density Unsaturated Zone Effective Porosity -0.96 The two parameters are s

correlated. Saturated Zone Soil Density Saturated Zone Effective Porosity -0.96 The two parameters are scorrelated.

Kd of U-238 in Contaminated Zone Kd of U-234 in Contaminated Zone 0.99 To ensure the same Kd v

different isotopes of the 

Kd of U-238 in Unsaturated Zone Kd of U-234 in Unsaturated Zone 0.99 Same as above.

Kd of U-238 in Saturated Zone Kd of U-234 in Saturated Zone 0.99 Same as above
ISCORS Technical Report 2004-03 A-22 Final, February 2005 Table A.9

RESRAD-Offsite Baseline Parameter Values and Distributions

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

TitleTitle Scenario

dependent

Scenario defi

Intermediate time points

Number of points (32, 64, 128,256, 512, 1024, 2048, 4096)

(128) 32

 Linear spacing/Log Spacing linear Minimum time increment v 1Dose factor library (DOSFAC.BIN) DOSFAC6.BI

N

To consider s

Cut-off half life (180 days, 30 days, 6hours)

(180 days) 6 hours To include sh

in the analysi

Display update (0.25, 0.5, 1, 2, 4, 8,16 sec)

v 1

Use line draw character YesFirst InputBasic radiation dose limit (mrem/yr) (30) 25Exposure duration (yr) 30Number of unsaturated zone 1
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

Final, February 2005 A-23 ISCORS Technical Report 2004-03 Source Nuclide concentration (pCi/g) 0.0044 Scenario defi

soil density o

Source Release Release to groundwater, leach rate (1/yr) 0 Distribution Coefficients (ml/g) Contaminated zone Nuclide dependent (see Table A.1 Baseline Values and Distributions for the Kd Parameter) Geometric mean of distribution (see Table A.1 Baseline Values and Distributions for the Kd Parameter) Nuclide dependent (see Table A.1 Baseline Values and Distributions for the Kd Parameter) Unsaturated zone Same as above Same as above Same as above Saturated zone Same as above Same as above Same as above Sediment in surface water body v Same as above Same as above Same as above Fruit, grain, non-leafy fields v Same as above Same as above Same as above Leafy vegetable fields v Same as above Same as above Same as above Pasture, silage growing areas v Same as above Same as above Same as above
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

ISCORS Technical Report 2004-03 A-24 Final, February 2005 Livestock feed grain fields v Same as above Same as above Same as above Transfer Factors Soil to plant transfer factor [(pCi/kg)/(pCi/kg)] RESRAD-Of

plant types antransfer factoaccepts only oused for all p

Fruit, grain, non-leafy vegetables v Nuclide dependent (see Table A.2 Baseline Values and Distributions for the Plant Transfer Factor) Geometric mean of distribution (see Table A.2 Baseline Values and Distributions for the Plant Transfer Factor) Nuclide dependent (see Table A.2 Baseline Values and Distributions for the Plant Transfer Factor) Leafy vegetables v Same as above Same as above Same as above Pasture, silage v Same as above Same as above Same as above Livestock feed grain v Same as above Same as above Same as above Intake to animal product transfer factor
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

Final, February 2005 A-25 ISCORS Technical Report 2004-03 Meat [(pCi/kg)/(pCi/d)] Nuclide dependent (see Table A.3 Baseline Values and Distributions for the Meat Transfer Factor) Geometric mean of distribution (see Table A.3 Baseline Values and Distributions for the Meat Transfer Factor) Nuclide dependent (see Table A.3 Baseline Values and Distributions for the Meat Transfer Factor) Milk [(pCi/L)/(pCi/d)] Nuclide dependent (see Table A.4 Baseline Values and Distributions for the Milk Transfer Factor) Geometric mean of distribution (see Table A.4 Baseline Values and Distributions for the Milk Transfer Factor) Nuclide dependent (see Table A.4 Baseline Values and Distributions for the Milk Transfer Factor) Water to aquatic food transfer factor
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

ISCORS Technical Report 2004-03 A-26 Final, February 2005 Fish [(pCi/kg)/(pCi/L)] Nuclide dependent [see Table A.5 Baseline Values and Distributions for the Aquatic Food (Fish) Transfer Factor] Geometric mean of distribution [see Table A.5 Baseline Values and Distributions for the Aquatic Food (Fish) Transfer Factor] Nuclide dependent [see Table A.5 Baseline Values and Distributions for the Aquatic Food (Fish) Transfer Factor] Crustacea [(pCi/kg)/(pCi/L)] Nuclide dependent Not used Nuclide dependent / Not used Reporting Times Times at which output is reported (yr) 1, 3, 6, 12, 30, 75, 175, 420, 970 Storage Times Surface water (d) 1 Well water (d) 1 Fruits, grain, and non-leafy vegetables (d) 14 Leafy vegetables (d) 1
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

Final, February 2005 A-27 ISCORS Technical Report 2004-03 Pasture and silage (d) v 1 Livestock fod

divided into tRESRAD-Ofsilage, and (2

Livestock feed grain (d) v 45 Livestock fod

categories in pasture and si

Meat (d) 20 Milk (d) 1 Fish (d) 7 Crustacea and mollusks (d) 7 Site Properties Precipitation (m/yr) 1 Wind speed (m/s) (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) (10000) 404685 (100 acres) Length of contamination parallel to aquifer flow (m) (100) 636 (equivalent to the square root of area).
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

ISCORS Technical Report 2004-03 A-28 Final, February 2005 Depth of soil mixing layer (m) (0.15) 0.25* Triangular(0.0, 0.15, 0.6) Deposition velocity of dust (m/s) v (0.01) 0.002 Value decide

calculation foearlier version chapter. Irrigation applied per year (m/yr) 0.2 Evapotranspiration coefficient (0.5) 0.625* Uniform(0.5, 0.75) Runoff coefficient (0.2) 0.45* Uniform(0.1, 0.8) Rainfall erosion index v 200 The parametethe erosion ra

 Slope-length-steepness factor v 1 The paramete

erosin rate. Cropping management factor v 0.11 The parameteerosin rate. Conservation practice factor v 1 The parameteerosion rate. Contaminated zone Thickness (m) (2) 0.15 Plowing dept

 Total porosity (0.4) 0.426 Value calcula

density.
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

Final, February 2005 A-29 ISCORS Technical Report 2004-03 Erosion rate (m/yr) (0.0009856) 0 Continuous Log / No distribution was specified in dose analyses The paramete

RESRAD-Ofparameters. Berodibility facis 0, which wto get conservparameter is aRESRAD, the 

 Dry bulk density (g/cm3) (1.5) 1.52* Soil erodibility factor (tons/acre) v (0.3) 0 A value of 0 w

rate. The parcalculate the 

 Field capacity (0.3) 0.2 Value was de

consistence wbaseline valu

 Soil b parameter (5.3) 2.895** BoundedLogN(1.06, 0.66, 0.5, 30) Hydraulic conductivity (m/yr) (10) 9.974** BoundedLogN(2.3, 2.11, 0.004, 9250) Clean Cover Thickness (m) 0 No cover mat Total porosity (0.4) Not used Erosion rate (m/yr) (0.0009856) Not used No cover mat

value is calcuRESRAD-Ofparameters.
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

ISCORS Technical Report 2004-03 A-30 Final, February 2005 Dry bulk density (g/cm3) (1.5) Not used TruncN(1.52, 0.230, 0.001, 0.999) / not used No cover mat

 Soil erodibility factor (tons/acre) v (0.3) Not used No cover mat

used to calcul

 Volumetric water content v (0.05) Not used No cover matUnsaturated Zone Parameters Thickness (m) (4) 9.895** BoundedLogN(2.29 26, 1.276, 0.18, 320) Dry bulk density (g/cm3) (1.5) 1.52* TruncN(1.52, 0.230, 0.001, 0.999) Total porosity (0.4) 0.425* TruncN(0.425, 0.0867, 0.001, 0.999) Effective porosity (0.2) 0.355* TruncN(0.355, 0.0906, 0.001, 0.999) Field capacity (0.3) 0.2 Set to 0.2 to b

RESRAD def

Hydraulic conductivity (m/yr) (10) 9.974** BoundedLogN(2.3, 2.11, 0.004, 9250) Soil b parameter (5.3) 2.895** BoundedLogN(1.06, 0.66, 0.5, 30)
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

Final, February 2005 A-31 ISCORS Technical Report 2004-03 Longitudinal dispersivity (m) v 1 Saturated Zone Hydrological Data Thickness of saturated zone (m) v (100) 3000 Value selecte

mounding in 

Dry bulk density of saturated zone (g/cm3) (1.5) 1.52* TruncN(1.52, 0.230, 0.001, 0.999) Total porosity (0.4) 0.425* TruncN(0.425, 0.0867, 0.001, 0.999) Effective porosity (0.2) 0.355* TruncN(0.355, 0.0906, 0.001, 0.999) Hydraulic conductivity (m/yr) (100) 9.974** BoundedLogN(2.3, 2.11, 0.004, 9250) Hydraulic gradient (0.02) 0.00604** BoundedLogN(-5.1 1, 1.77, 7e-5, 0.5) Longitudinal dispersivity (m) v 10 Horizontal lateral dispersivity (m) v 3 Disperse vertically? v Yes Vertical lateral dispersivity (m) v 1 Do not disperse vertically? v No Value averaged over length of saturated zone Irrigation rate (m/yr) 0.2 Not used Vertical dispe
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

ISCORS Technical Report 2004-03 A-32 Final, February 2005 Evapotranspiration coefficient 0.5 Not used Runoff coefficient 0.2 Not used Depth of aquifer contributing to water source Well screen depth (below groundwater table) (m) 10 15.33* Triangular(6, 10, 30) Surface water body (below groundwater table) (m) v 10 Agriculture Area Parameters Fruite, grain, and non-leafy field Area (m2) v 1000 Fraction of area directly over primary contamination v 0 Scenario defi

 Irrigation applied per year (m/yr) v 0.2 Evapotranspiration coefficient v (0.5) 0.625* Uniform(0.5, 0.75) Runoff coefficient v (0.2) 0.45* Uniform(0.1,0.8) Depth of soil mixing layer or plow layer (m) v (0.15) 0.25* Triangular(0.0, 0.15, 0.6)
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

Final, February 2005 A-33 ISCORS Technical Report 2004-03 Total water filled porosity v 0.3 In RESRAD, 

calculated usisaturated hydparameter, ansaturated hydparameter, anlonger input pagricultural a

Erosion rate (m/yr) v 0.0009856 The paramete

RESRAD-Ofparameters. IRESRAD and 0.001. Dry bulk density of soil (g/cm3) v (1.5) 1.52* TruncN(1.52, 0.230, 0.001, 0.999) Soil erodibility factor (tons/acre) v 0.3 The paramete

erosion rate. Slope-length-steepness factor v 1 The parameteerosion rate. Cropping management factor v 0.11 The parameteerosion rate. Conservation practice factor v 1 The parameteerosion rate. Leafy vegetable field Area (m2) v 1000
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

ISCORS Technical Report 2004-03 A-34 Final, February 2005 Fraction of area directly over primary contamination v 0 Scenario defi

 Irrigation applied per year (m/yr) v 0.2 Evapotranspiration coefficient v (0.5) 0.625* Uniform(0.5, 0.75) Runoff coefficient v (0.2) 0.45* Uniform(0.1, 0.8) Depth of soil mixing layer or plow layer (m) v (0.15) 0.25* Triangular(0.0, 0.15, 0.6) Total water filled porosity v 0.3 In RESRAD, 

calculated usisaturated hydparameter, ansaturated hydparameter, anlonger input pagricultural a

Erosion rate (m/yr) v 0.0009856 The value is c

RESRAD-Ofparameters. IRESRAD and 0.001. Dry bulk density of soil (g/cm3) v (1.5) 1.52* TruncN(1.52, 0.230, 0.001, 0.999) Soil erodibility factor (tons/acre) v 0.3 The paramete

erosion rate. Slope-length-steepness factor v 1 The parameteerosion rate.
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

Final, February 2005 A-35 ISCORS Technical Report 2004-03 Cropping management factor v 0.11 The paramete

erosion rate. Conservation practice factor v 1 The parameteerosion rate. Livestock Feed Growing Area Parameters Pasture and silage field Area (m2) v 10000 Fraction of area directly over primary contamination v 0 Scenario defi

 Irrigation applied per year (m/yr) v (0.2) 0 No irrigation 

growing area

 Evapotranspiration coefficient v (0.5) 0.625 * Uniform(0.5, 0.75) Runoff coefficient v (0.2) 0.45 * Uniform(0.1, 0.8) Depth of soil mixing layer or plow layer (m) v (0.15) 0.25 * Triangular(0.0, 0.15, 0.6) Total water filled porosity v 0.3 In RESRAD, 

calculated usisaturated hydparameter, ansaturated hydparameter, anlonger input pagricultural a
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

ISCORS Technical Report 2004-03 A-36 Final, February 2005 Erosion rate (m/yr) v 0.0009856 The value is c

RESRAD-Ofparameters. IRESRAD and 0.001. Dry bulk density of soil (g/cm3) v (1.5) 1.52* TruncN(1.52, 0.230, 0.001, 0.999) Soil erodibility factor (tons/acre) v 0.3 The paramete

erosion rate. Slope-length-steepness factor v 1 The parameteerosion rate. Cropping management factor v 0.11 The parameteerosion rate. Conservation practice factor v 1 The parameteerosion rate. Grain field Area (m2) v 10000 Fraction of area directly over primary contamination v 0 Irrigation applied per year (m/yr) v (0.2) 0 No irrigation 

growing area

 Evapotranspiration coefficient v (0.5) 0.625* Uniform(0.5, 0.75) Runoff coefficient v (0.2) 0.45* Uniform(0.1, 0.8) Depth of soil mixing layer or plow layer (m) v (0.15) 0.25* Triangular(0.0, 0.15, 0.6)
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

Final, February 2005 A-37 ISCORS Technical Report 2004-03 Total water filled porosity v 0.3 In RESRAD, 

calculated usisaturated hydparameter, ansaturated hydparameter, anlonger input pagricultural a

Erosion rate (m/yr) v 0.0009856 The paramete

RESRAD-Ofparameters. IRESRAD and 0.001. Dry bulk density of soil (g/cm3) v (1.5) 1.52* TruncN(1.52, 0.230, 0.001, 0.999) Soil erodibility factor (tons/acre) v 0.3 The paramete

erosion rate. Slope-length-steepness factor v 1 The parameteerosion rate. Cropping management factor v 0.11 The parameteerosion rate. Conservation practice factor v 1 The parameteerosion rate.
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

ISCORS Technical Report 2004-03 A-38 Final, February 2005 Surface Water Body Parameters Sediment delivery ratio v (1) 0.5 / Uniform(0, 1) Used to deter

eroded radionsurface water 

Volume of surface water body (m3) v 150000 The surface w

to be of a circof 100 m and dose analyses

Mean residence time of water in surface water body (y) v (1) 9.609 x 10-4 (8.4175 hr) The baseline 

based on the water body anm3/sec. Air Transport Parameters Chi/Q (s/m3) for fruit, grain, non-leafy vegetable field v (0) 5.97 x 10-6 Value from C

of 800 m. Chi/Q (s/m3) for leafy vegetable field v (0) 5.97 x 10-6 Value from Cof 800 m. Chi/Q (s/m3) for pasture and silage field v (0) 5.97 x 10-6 Value from Cof 800 m. Chi/Q (s/m3) for grain field v (0) 5.97 x 10-6 Value from Cof 800 m. Groundwater Transport Parameters Distance from downgradient edge of contamination to 
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

Final, February 2005 A-39 ISCORS Technical Report 2004-03 Well in the direction parallel to aquifer flow (m) v (100) 800 Assumed the 

center of the 

Surface water body in the direction parallel to aquifer flow (m) v (100) 800 Assumed the 

water body is the primary c

Distance from center of contamination to Well in the direction perpendicular to aquifer flow (m) v 0 Assumed the 

center of the which is locathe primary c

Near edge of surface water body in the direction parallel to aquifer flow (m) v (-125) -100 The surface w

to be of a circof 100 m. Far edge of surface water body in the direction parallel to aquifer flow (m) v (125) 100 Same as abov

Convergence criterion (fractional accuracy desired) 0.001 Number of sub zones (to model dispersion of progeny produced in transit) Main sub zones in saturated zone v 1 Minor sub zones in last main sub zone in saturated zone v Not used
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

ISCORS Technical Report 2004-03 A-40 Final, February 2005 Main sub zones in each partially saturated zone v 1 Minor sub zones in last main sub zone in each partially saturated zone v Not used Retardation and dispersion treatment Nuclide specific retardation in all sub zones, longitudinal dispersion in all but the sub zone of transformation? v Yes Longitudinal dispersion in all sub zones, nuclide specific retardation in all but the sub zone of transformation, parent retardation in zone of transformation? v No Longitudinal dispersion in all sub zones, nuclide specific retardation in all but the sub zone of transformation, progeny retardation in zone of transformation? v No Water Use Parameters Human consumption Quantify (L/yr) (510) 409.5 ** TruncLogN(6.015, 0.489, 0.001, 0.999)
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

Final, February 2005 A-41 ISCORS Technical Report 2004-03 Fraction of water from surface body 0 Assuming 90

is from a loca

 Fraction of water from well (1) 0.9 Assuming 90

is from a loca

 Number of household individuals v 4 The paramete

total amount affected area. Household purposes Quantify (L/yr) v 225 Fraction of water from surface body 0 Fraction of water from well 1 Beef cattle Quantify (L/yr) 50 Fraction of water from surface body v (0) 0.5 Fraction of water from well v (1) 0.5 Number of cattle v 2 The parametetotal amount affected area. Dairy cows Quantify (L/yr) 160 Fraction of water from surface body v (0) 0.5
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

ISCORS Technical Report 2004-03 A-42 Final, February 2005 Fraction of water from well v (1) 0.5 Number of cows v 2 The paramete

total amount affected area. Irrigation applied per year Fruit, grain, non-leafy vegetables Quantify (m/yr) v 0.2 Value should irrigation rate farmed field. Fraction of water from surface body v (0) 0.5 Fraction of water from well v (1) 0.5 Area of plot (m2) v 1000 Value should 

size specified field. Leafy vegetables Quantify (m/yr) v 0.2 Value should irrigation rate farmed field. Fraction of water from surface body v (0) 0.5 Fraction of water from well v (1) 0.5
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

Final, February 2005 A-43 ISCORS Technical Report 2004-03 Area of plot (m2) v 1000 Value should 

size specified field. Pasture and silage Quantify (m/yr) v (0.2) 0 Value should irrigation rate farmed field. Fraction of water from surface body v (0) 0.5 Fraction of water from well v (1) 0.5 Area of plot (m2) v 10000 Value should size specified field. Livestock feed grain Quantify (m/yr) v (0.2) 0 Value should irrigation rate farmed field. Fraction of water from surface body v (0) 0.5 Fraction of water from well v (1) 0.5 Area of plot (m2) v 10000 Value should size specified field.
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

ISCORS Technical Report 2004-03 A-44 Final, February 2005 Well pumping rate (m3/yr) 250 Value kept c

baseline valu

Well pumping rate needed to specified water use (m3/yr) v 4884.17 The value wa

RESRAD-Ofvarious water listed for refe

Ingestion Rates Consumption rate Drinking water (L/yr) (510) 409.5** TruncLogN(6.015, 0.489, 0.001, 0.999) Fish (kg/yr) (5.4) 155.6* / Triangular(2.0, 56.3, 408.5) Baseline distr

Exposure Fac

 Other aquatic food (kg/yr) (0.9) 0 Scenario defi Fruit, grain, non-leafy vegetables (kg/yr) (160) 210.33* Triangular(135, 178, 318) Leafy vegetables (kg/yr) (14) 22.667* / Triangular(13, 25, 30) Meat (kg/yr) (63) 222.1* / Triangular(5.0, 72.6, 588.7) Milk (L/yr) (92) 120.67* Triangular(60, 102, 200) Soil (incidental) (g/yr) (36.5) 18.27* Triangular(0, 18.3, 36.5)
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

Final, February 2005 A-45 ISCORS Technical Report 2004-03 Fraction from affected area Drinking water (1) 0.9 To be consist

value for RES

 Fish (0.5) 0.463* Triangular(0, 0.39, 1) Other aquatic food (0.5) 0 Scenario defi Fruit, grain, non-leafy vegetables 0.5 Leafy vegetables 0.5 Meat 1 Milk 1 Livestock Intakes Meat Cows Water (L/d) 50 Value kept co

specified in "

 Pasture and silage (kg/d) v 14 RESRAD-Of

fodder ingestin RESRAD tingestion rate ingestion rate 

 Grain (kg/d) v 54 RESRAD-Of

fodder ingestin RESRAD tingestion rate ingestion rate 
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

ISCORS Technical Report 2004-03 A-46 Final, February 2005 Soil from pasture and silage (kg/d) v 0.1 RESRAD-Of

livestock tota0.5 kg/d used ingestion rate of 0.1 kg/d anfrom grain of 

 Soil from grain (kg/d) v 0.4 RESRAD-Of

livestock tota0.5 kg/d used ingestion rate of 0.1 kg/d anfrom grain of 

Milk Cows Water (L/d) 160 Water kept co

specified in "

 Pasture and silage (kg/d) v 44 RESRAD-Of

fodder ingestin RESRAD tingestion rate ingestion rate 

 Grain (kg/d) v 11 RESRAD-Of

ingestion rate RESRAD to pingestion rate ingestion rate 
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

Final, February 2005 A-47 ISCORS Technical Report 2004-03 Soil from pasture and silage (kg/d) v 0.4 RESRAD-Of

livestock tota0.5 kg/d used ingestion rate of 0.4 kg/d anfrom grain of 

 Soil from grain (kg/d) v 0.1 RESRAD-Of

livestock tota0.5 kg/d used ingestion rate of 0.4 kg/d anfrom grain of 

Livestock Feed Factors Pasture and silage Wet weight crop yield (kg/m2) v 1.1 RESRAD-Of

two categorieand (2) grain. pasture and sisame as those 

 Duration of growing season (y) v 0.08 See "wet wei Foliage to food transfer coefficient v 1 See "wet wei
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

ISCORS Technical Report 2004-03 A-48 Final, February 2005 Weathering removal constant (1/yr) v 20 See "wet wei

 Foliar interception factor for irrigation v 0.25 See "wet wei Foliar interception factor for dust v 0.25 See "wet wei Root depth (m) v 0.9 RESRAD use

for all plant cRESRAD-Ofdepths for dif

Grain Wet weight crop yield (kg/m2) v 0.7 RESRAD-Of

two categorieand (2) grain. were set to thnon-leafy pla

 Duration of growing season (y) v 0.17 See "wet wei Foliage to food transfer coefficient v 0.1 See "wet wei Weathering removal constant (1/yr) v 20 See "wet wei Foliar interception factor for irrigation v 0.25 See "wet wei Foliar interception factor for dust v 0.25 See "wet wei
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

Final, February 2005 A-49 ISCORS Technical Report 2004-03 Root depth (m) v 1.2 RESRAD use

for all plant cRESRAD-Ofdepths for dif

Plant Factors Fruit, grain, non-leafy Wet weight crop yield (kg/m2) (0.7) 1.751** TruncLogN(0.56, 0.48, 0.001, 0.999) Duration of growing season (y) 0.17 Foliage to food transfer coefficient 0.1 Weathering removal constant (1/yr) (20) 35.70* Triangular(5.1, 18, 84) Foliar interception factor for irrigation 0.25 Foliar interception factor for dust 0.25 Root depth (m) v 1.2 RESRAD use

for all plant cRESRAD-Ofdepths for dif

Leafy vegetables Wet weight crop yield (kg/m2) 1.5 Duration of growing season (y) 0.25
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

ISCORS Technical Report 2004-03 A-50 Final, February 2005 Foliage to food transfer coefficient 1 Weathering removal constant (1/yr) 20 Foliar interception factor for irrigation (0.25) 0.56* Triangular(0.06, 0.67, 0.95) Foliar interception factor for dust 0.25 Root depth (m) v 0.9 RESRAD use

for all plant cRESRAD-Ofdepths for dif

Inhalation and External Gamma Data Inhalation rate (m3/yr) (8400) 8627* Triangular(4380, 8400, 13100) Mass loading for inhalation (g/m3) (0.0001) 2.45E-05* Continuous Linear Mean on-site mass loading (g/m3) (0.0001) 2.45E-05 Indoor dust filtration factor (0.4) 0.55* Uniform(0.15, 0.95) External gamma shielding factor (0.7) 0.27** BoundedLogN(-1.3, 0.59, 0.044, 1) External Radiation Shape and Area Factors Shape of the plane of the primary contamination Circular? Yes Polygonal? No
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

Final, February 2005 A-51 ISCORS Technical Report 2004-03 On-site Scale (m) not used The receptor 

 Receptor location X (m): not used The receptor  Receptor location Y (m): not used The receptor  Off-site Scale (m) v 2500 Receptor location X (m): v 2410 Value determ

selected scalecontaminated distance (800 contaminated 

 Receptor location Y (m): v 1250 Value determ

selected scale

Occupancy Factors Fraction of time spent on primary contamination (whether cultivated or not) Indoors (0.5) 0 The receptor  Outdoors 0 The receptor Fraction of time spent off-site, within the range of radiation emanating from primary contamination (whether cultivated or not)
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

ISCORS Technical Report 2004-03 A-52 Final, February 2005 Indoors v (0) 0.651* Value selecte

the RESRAD 

 Outdoors v (0.4) 0.25 Value selecte

RESRAD bas

Fraction of time spent in farmed areas (including primary and secondary contaminated areas) Fruit, grain and non-leafy vegetable fields v (0.1) 0.0625 Value was de

the outdoor tievenly among 

 Leafy vegetable fields v (0.1) 0.0625 Value was de

the outdoor tievenly among 

 Pasture and silage fields v (0.1) 0. 7135 Time fraction 

determined by time fractions the four off-sassumed to be field, thereforinside the houfraction spent 

 Livestock grain fields v (0.1) 0.0625 Value was de

the outdoor tievenly among 
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

Final, February 2005 A-53 ISCORS Technical Report 2004-03 Radon Data Effective radon diffusion coefficient of cover (m2/s) 2 x 10-6 not used The house is 

primary conta

Effective radon diffusion coefficient of contaminated zone (m2/s) not used Same as abov

Effective radon diffusion coefficient of floor (m2/s) 3 x 10-7 not used Same as abov

Thickness of floor and foundation (m) 0.15 not used Same as abovDensity of floor and foundation (m) 2.4 not used Same as abovTotal porosity of floor and foundation 0.1 not used Same as abovVolumetric water content of floor and foundation 0.03 not used Same as abovDepth of foundation below ground level (m) -1 not used Same as abovRadon vertical dimension of mixing (m) 2 not used Same as abovBuilding room height (m) 2.5 not used Same as abovBuilding air exchange rate (1/h) 0.5 not used Same as abovBuilding indoor area factor 0 not used Same as abovRn-222 emanation coefficient 0.25 not used Same as abovRn-220 emanation coefficient 0.15 not used Same as abov
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

ISCORS Technical Report 2004-03 A-54 Final, February 2005 C-14 Data Thickness of evasion layer for C-14 in soil (m) 0.3 0.367* Triangular(0.2, 0.3, 0.6) C-14 evasion flux rate from soil 7 x 10-7 C-12 evasion flux rate from soil 1 x 10-10 Fraction of vegetation carbon absorbed from soil 0.02 Fraction of vegetation carbon absorbed from air 0.98 User selected inhalation DCF for C-14/DCF for CO2 88.9 Mass Fraction of C-12 Contaminated soil 0.03 Local water 0.00002 Fruit, grain, non-leafy vegetables 0.4 Leafy vegetables 0.09 Pasture and silage v 0.09 Grain v 0.4 Meat 0.24 Milk 0.07 Tritium Data Humidity in air (g/m3 ) (8) 7.243** TruncLogN(1.98, 0.334, 0.001, 0.999)
Table A.9 RESRAD-Offsite Baseline Parameter Values and Distributions (continued)

Input Parameters New

Parameter

in

RESRADOffsite ***

RESRAD-OffsiteDefault Values

BaselineValues (ifother thanthe default)

NUREG/CR-6697ProbabilisticDistribution/BaselineDistributions (ifother thanNUREG/CR-6697)

Comments

Final, February 2005 A-55 ISCORS Technical Report 2004-03 Mass fraction of water in Fruit, grain and non-leafy vegetables v 0.8 In RESRAD, 

code. Leafy vegetable v 0.8 In RESRAD, code. Pasture and silage v 0.8 In RESRAD, code. Grain v 0.8 In RESRAD, code. Meat v 0.6 In RESRAD, code. Milk v 0.88 In RESRAD, code.
ISCORS Technical Report 2004-03 A-56 Final, February 2005 Table A.10 RESRAD-Offsite Baseline Parameter C

orrelations for Probabilistic Anal

yses

Parameter 1 Parameter 2 Correlation

Coefficient

Comme

Including all the correlations in Table A.8 and thefollowingsKd of Co-57 in sediment of surface water body Kd of Co-60 in sediment of surface water body 0.99 To ensu

was usethe sam

Kd of Co-57 in fruit, grain, non-leafy fields Kd of Co-60 in fruit, grain, non-leafy fields 0.99 Same as 

Kd of Co-57 in leafy vegetable fields Kd of Co-60 in leafy vegetable fields 0.99 Same as Kd of Co-57 in pasture, silage growing areas Kd of Co-60 in pasture, silage growing areas 0.99 Same as Kd of Co-57 in livestock feed grain fields Kd of Co-60 in livestock feed grain fields 0.99 Same as Kd of Cs-134 in sediment of surface water body Kd of Cs-137 in sediment of surface water body 0.99 Same as Kd of Cs-134 in fruit, grain, non-leafy fields Kd of Cs-137 in fruit, grain, non-leafy fields 0.99 Same as Kd of Cs-134 in leafy vegetable fields Kd of Cs-137 in leafy vegetable fields 0.99 Same as Kd of Cs-134 in pasture, silage growing areas Kd of Cs-137 in pasture, silage growing areas 0.99 Same as Kd of Cs-134 in livestock feed grain fields Kd of Cs-137 in livestock feed grain fields 0.99 Same as Kd of I-125 in sediment of surface water body Kd of I-131 in sediment of surface water body 0.99 Same as Kd of I-125 in fruit, grain, non-leafy fields Kd of I-131 in fruit, grain, non-leafy fields 0.99 Same as Kd of I-125 in leafy vegetable fields Kd of I-131 in leafy vegetable fields 0.99 Same as Kd of I-125 in pasture, silage growing areas Kd of I-131 in pasture, silage growing areas 0.99 Same as Kd of I-125 in livestock feed grain fields Kd of I-131 in livestock feed grain fields 0.99 Same as Kd of Pu-238 in sediment of surface water body Kd of Pu-239 in sediment of surface water body 0.99 Same as 
Table A.10 RESRAD-Offsite Baseline Parameter Correlations for Probabilistic Analyses (cont

Parameter 1 Parameter 2 Correlation

Coefficient

Comme

Final, February 2005 A-57 ISCORS Technical Report 2004-03

Kd of Pu-238 in fruit, grain, non-leafy fields Kd of Pu-239 in fruit, grain, non-leafy fields 0.99 Same as 

Kd of Pu-238 in leafy vegetable fields Kd of Pu-239 in leafy vegetable fields 0.99 Same as Kd of Pu-238 in pasture, silage growing areas Kd of Pu-239 in pasture, silage growing areas 0.99 Same as Kd of Pu-238 in livestock feed grain fields Kd of Pu-239 in livestock feed grain fields 0.99 Same as Kd of Ra-226 in sediment of surface water body Kd of Ra-228 in sediment of surface water body 0.99 Same as Kd of Ra-226 in fruit, grain, non-leafy fields Kd of Ra-228 in fruit, grain, non-leafy fields 0.99 Same as Kd of Ra-226 in leafy vegetable fields Kd of Ra-228 in leafy vegetable fields 0.99 Same as Kd of Ra-226 in pasture, silage growing areas Kd of Ra-228 in pasture, silage growing areas 0.99 Same as Kd of Ra-226 in livestock feed grain fields Kd of Ra-228 in livestock feed grain fields 0.99 Same as Kd of Sr-89 in sediment of surface water body Kd of Sr-90 in sediment of surface water body 0.99 Same as Kd of Sr-89 in fruit, grain, non-leafy fields Kd of Sr-90 in fruit, grain, non-leafy fields 0.99 Same as Kd of Sr-89 in leafy vegetable fields Kd of Sr-90 in leafy vegetable fields 0.99 Same as Kd of Sr-89 in pasture, silage growing areas Kd of Sr-90 in pasture, silage growing areas 0.99 Same as Kd of Sr-89 in livestock feed grain fields Kd of Sr-90 in livestock feed grain fields 0.99 Same as Kd of Th-228 in sediment of surface water body Kd of Th-229 in sediment of surface water body 0.99 Same as Kd of Th-228 in fruit, grain, non-leafy fields Kd of Th-229 in fruit, grain, non-leafy fields 0.99 Same as Kd of Th-228 in leafy vegetable fields Kd of Th-229 in leafy vegetable fields 0.99 Same as Kd of Th-228 in pasture, silage growing areas Kd of Th-229 in pasture, silage growing areas 0.99 Same as Kd of Th-228 in livestock feed grain fields Kd of Th-229 in livestock feed grain fields 0.99 Same as 
Table A.10 RESRAD-Offsite Baseline Parameter Correlations for Probabilistic Analyses (cont

Parameter 1 Parameter 2 Correlation

Coefficient

Comme

ISCORS Technical Report 2004-03 A-58 Final, February 2005

Kd of Th-228 in sediment of surface water body Kd of Th-230 in sediment of surface water body 0.99 Same as 

Kd of Th-228 in fruit, grain, non-leafy fields Kd of Th-230 in fruit, grain, non-leafy fields 0.99 Same as Kd of Th-228 in leafy vegetable fields Kd of Th-230 in leafy vegetable fields 0.99 Same as Kd of Th-228 in pasture, silage growing areas Kd of Th-230 in pasture, silage growing areas 0.99 Same as Kd of Th-228 in livestock feed grain fields Kd of Th-230 in livestock feed grain fields 0.99 Same as Kd of Th-228 in sediment of surface water body Kd of Th-232 in sediment of surface water body 0.99 Same as Kd of Th-228 in fruit, grain, non-leafy fields Kd of Th-232 in fruit, grain, non-leafy fields 0.99 Same as Kd of Th-228 in leafy vegetable fields Kd of Th-232 in leafy vegetable fields 0.99 Same as Kd of Th-228 in pasture, silage growing areas Kd of Th-232 in pasture, silage growing areas 0.99 Same as Kd of Th-228 in livestock feed grain fields Kd of Th-232 in livestock feed grain fields 0.99 Same as Kd of Tl-201 in sediment of surface water body Kd of Tl-202 in sediment of surface water body 0.99 Same as Kd of Tl-201 in fruit, grain, non-leafy fields Kd of Tl-202 in fruit, grain, non-leafy fields 0.99 Same as Kd of Tl-201 in leafy vegetable fields Kd of Tl-202 in leafy vegetable fields 0.99 Same as Kd of Tl-201 in pasture, silage growing areas Kd of Tl-202 in pasture, silage growing areas 0.99 Same as Kd of Tl-201 in livestock feed grain fields Kd of Tl-202 in livestock feed grain fields 0.99 Same as Kd of U-233 in sediment of surface water body Kd of U-234 in sediment of surface water body 0.99 Same as Kd of U-233 in fruit, grain, non-leafy fields Kd of U-234 in fruit, grain, non-leafy fields 0.99 Same as Kd of U-233 in leafy vegetable fields Kd of U-234 in leafy vegetable fields 0.99 Same as Kd of U-233 in pasture, silage growing areas Kd of U-234 in pasture, silage growing areas 0.99 Same as 
Table A.10 RESRAD-Offsite Baseline Parameter Correlations for Probabilistic Analyses (cont

Parameter 1 Parameter 2 Correlation

Coefficient

Comme

Final, February 2005 A-59 ISCORS Technical Report 2004-03

Kd of U-233 in livestock feed grain fields Kd of U-234 in livestock feed grain fields 0.99 Same as 

Kd of U-233 in sediment of surface water body Kd of U-235 in sediment of surface water body 0.99 Same as Kd of U-233 in fruit, grain, non-leafy fields Kd of U-235 in fruit, grain, non-leafy fields 0.99 Same as Kd of U-233 in leafy vegetable fields Kd of U-235 in leafy vegetable fields 0.99 Same as Kd of U-233 in pasture, silage growing areas Kd of U-235 in pasture, silage growing areas 0.99 Same as Kd of U-233 in livestock feed grain fields Kd of U-235 in livestock feed grain fields 0.99 Same as Kd of U-233 in sediment of surface water body Kd of U-238 in sediment of surface water body 0.99 Same as Kd of U-233 in fruit, grain, non-leafy fields Kd of U-238 in fruit, grain, non-leafy fields 0.99 Same as Kd of U-233 in leafy vegetable fields Kd of U-238 in leafy vegetable fields 0.99 Same as Kd of U-233 in pasture, silage growing areas Kd of U-238 in pasture, silage growing areas 0.99 Same as Kd of U-233 in livestock feed grain fields Kd of U-238 in livestock feed grain fields 0.99 Same as 
ISCORS Technical Report 2004-03 A-60 Final, February 2005 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) Com

Val

Case Title Default case for RESRAD-Build Scenario dependent Scenario de

Input File Site1.bld Scenario dependent Time Parameters Exposure Duration (d) 365 Indoor Fraction 0.5 0.651** Continuous Linear Not used du

values. Time for Calculation (yr) 1 Max. No. of Points for Time Integration 257 Building Parameters Number of Rooms 1 Deposition Velocity (m/s) (0.01) 3.9E-4** LogU(2.7E-6, 2.7E-3) Resuspension Rate (1/s) (5.0E-7) 1.3E-6** 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)
Table A.11 RESRAD-BUILD Baseline Parameter Values and Distributions (continued)

Input Parameters RESRAD-BUILD

Default Values

Baseline Values

(if other than

the default)

NUREG/CR-6697

Probabilistic Distributions /

Baseline Distributions (if

other than NUREG/CR6697) 

Com

Val

Final, February 2005 A-61 ISCORS Technical Report 2004-03 Area of Room (m2

)

(36) 150 Larger than 

source area

Height (m) 2.5 2.5 Triangular(2.4, 3.7, 9.1)/No

distribution

Radiological UnitsActivity pCiDose mremReceptor ParametersReceptor No. 1Room No. 1Time Fraction 1Breathing Rate (m3/d) (18) 30.5* Triangular(12, 33.6, 46) This distrib

in an occup

Ingestion Rate (m2/h) (0.0001) 0 LogU(2.8E-5, 2.9E-4) / No

distribution

Good hygie

Location (m) (1, 1, 1) (0, 5.6, 1)Shielding ParameterSource 1/ Receptor 1

Thickness (cm) 0 Triangular( 0, 0, 30) No shieldin
Table A.11 RESRAD-BUILD Baseline Parameter Values and Distributions (continued)

Input Parameters RESRAD-BUILD

Default Values

Baseline Values

(if other than

the default)

NUREG/CR-6697

Probabilistic Distributions /

Baseline Distributions (if

other than NUREG/CR6697) 

Com

Val

ISCORS Technical Report 2004-03 A-62 Final, February 2005 Density (g/cc) 2.4 Uniform (2.2, 2.6) Material Concrete Source Parameters For Source 1 in Room 1 Type Volume Direction (X) Z Only for a 

source. Location (m) 0, 0, 0 Area (m2) (36) 100 Parameter u

area sourc

Air Release Fraction 0.1 0.357 Triangular(1E-6., 0.07, 1) Direct Ingestion (g/h) 0 Unit for a p

source is (1

Number of Wall Regions 1 Only for a Material Type Concrete Only for a Wall Region Parameters for Region 1 Only for a 

Thickness (cm) (15) 50 Density (g/cc) (2.4) 1.52 Density for Erosion (cm/d) 2.4E-8 1.87e-7* Triangular(0,0,5.6E-7)
Table A.11 RESRAD-BUILD Baseline Parameter Values and Distributions (continued)

Input Parameters RESRAD-BUILD

Default Values

Baseline Values

(if other than

the default)

NUREG/CR-6697

Probabilistic Distributions /

Baseline Distributions (if

other than NUREG/CR6697) 

Com

Val

Final, February 2005 A-63 ISCORS Technical Report 2004-03 Radon Diffusion Coefficient (m2/s) 2.0E-5 Porosity (0.1) 0.4 Radon Emanation Fraction 0.2 Radionuclide Concentration (pCi/g) (1.0 for Co-60) 1.0 for all the radionuclides of concern Total activi

point sourcis pCi/m, fopCi/m2. Tritium Parameters Only for a 

Area (m2) (36) 100 Wet+Dry Zone Thickness (cm) (10) 50 Dry Zone Thickness (cm) 0 Volumetric Water Content 0.03 0.35 Value shou

porosity. Water Fraction Available for Evaporation 1 0.75 Triangular(0.5, 0.75, 1) Total Porosity of Contaminated Material (0.1) 0.4 Density of Material (g/cm3) (2.4) 1.52 Humidity (g/m3) (8) 9.8* Uniform (6.5, 13.1) This distribhumidity in
Table A.11 RESRAD-BUILD Baseline Parameter Values and Distributions (continued)

Input Parameters RESRAD-BUILD

Default Values

Baseline Values

(if other than

the default)

NUREG/CR-6697

Probabilistic Distributions /

Baseline Distributions (if

other than NUREG/CR6697) 

Com

Val

ISCORS Technical Report 2004-03 A-64 Final, February 2005 Erosion Rate (cm/d) 2.4E-8 1.87e-7* Triangular(0,0,5.6E-7) Direct Ingestion Rate (g/h) 0 Good hygie

Air Release Fraction 0.1 0.357 Triangular(1E-6., 0.07, 1) Deposition velocity (m/s) (0.01) 0 ** Geometric mean value of the distribution * Mean value of the distribution ( ) RESRAD-BUILD default value not used as baseline value
Appendix B

RESRAD and RESRAD-BUILD Codes

Final, February 2005 B-1 ISCORS Technical Report 2004-03

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.1 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. 
ISCORS Technical Report 2004-03 B-2 Final, February 2005

On-Site Biotic Contamination

On-Site

Direct Exposure

On-Site Air

Concentration Dust/

H-3

Radon

Plant Foods

Livestock Meat

Milk

Aquatic

Foods

On-Site Water

Contamination

On-Site Soil

Contamination

External

Radiation

Ingestion

Effective 

Dose

Equivalent/

Excess

Cancer Risk

to an 

Exposed

Individual

Residual

Radioactive

Material

In Soil

Source

Environmental

Pathway

Exposure

Pathway

Dose or

Cancer Risk

Inhalation

Figure B.1. Graphical Representation of Pathways Considered in RESRAD

The RESRAD-BUILD 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-BUILD code considers the releases of radionuclides

into the indoor air by diffusion, mechanical removal, or erosion. Seven exposure pathways are

considered in RESRAD-BUILD: (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.
Final, February 2005 B-3 ISCORS Technical Report 2004-03

RESRAD-BUILD Pathways

Rn

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).
ISCORS Technical Report 2004-03 B-4 Final, February 2005

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.
Final, February 2005 B-5 ISCORS Technical Report 2004-03

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.
ISCORS Technical Report 2004-03 B-6 Final, February 2005

Table B.1 Listing of Input Data and Information Needed for Sample

Generation

Input Data Description

Sampling Parameters

Random Seed 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 Observations Number of sample values to be generated for each input variable

for each repetition. The maximum number allowed is 2001

Number of Repetitions Number of times probabilistic analysis is repeated.

Sampling Techniques

Latin Hypercube 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

Simple Random (Monte

Carlo)

The desired number of observations is obtained at random from

the whole distribution.

Grouping of Observations

Correlated or

Uncorrelated

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

Random The samples of each variable are grouped together at random. 

Some pairs of variables may be correlated just by chance.

Statistical Distributions

Statistical Distribution

and Statistical Parameters

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.

Input Rank Correlations

Variable 1, Variable 2 Two variables for which rank correlation is specified

Rank Correlation

Coefficient

The specified input rank correlation coefficient between two

variables

 
Final, February 2005 B-7 ISCORS Technical Report 2004-03

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-BUILD 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
ISCORS Technical Report 2004-03 B-8 Final, February 2005

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-BUILD, 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).
Final, February 2005 B-9 ISCORS Technical Report 2004-03

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

Scenario S.” 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.
ISCORS Technical Report 2004-03 B-10 Final, February 2005

Iman, R.L. and M.J. 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, and MEPAS.” 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, and MEPAS.” 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, and MEPAS.” Environ. Eng. Sci. 16(1):67–80. 

1999a.
Final, February 2005 B-11 ISCORS Technical Report 2004-03

Whelan, G., et al. “Benchmarking of the Vadose-Zone Module Associated with Three Risk

Assessment Models: RESRAD, MMSOILS, and MEPAS.” 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.

Appendix C

Incinerator Control/Release Fractions

Final, February 2005 C-1 ISCORS Technical Report 2004-03

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 / F (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.1. 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.1. 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.
ISCORS Technical Report 2004-03 C-2 Final, February 2005

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,
Final, February 2005 C-3 ISCORS Technical Report 2004-03

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. 
ISCORS Technical Report 2004-03 C-4 Final, February 2005

Table C.1 Volatilization Fractions Recommended by Oztunali and Roles (1984)

for the Reference Pathological and Hazardous Waste Incinerators

Nuclide Decontamination Factor Release Fraction

H-3 1.1 0.9

C-14 1.3 0.75

Cl-36 100 0.01

Tc-99 100 0.01

Ru-103 100 0.01

Ru-106 100 0.01

I-125 100 0.01

I-129 100 0.01

All others 400 0.0025

Table C.2 Summary Range of Partitioning Values Found in the Literature by

Aaberg et al. (1995a)

Element Bottom Ash or Slag Fly Ash Stack Emissions

Cs 60-90 30-50 0.2

Sr 45-95 2-20 0.05

Zr 60-95 40-60 <1

Co 70-98 12-20 0.5

Zn 30-70 20-60 1

Sb 10-80 20-80 1

U 65-100 1-35 <1
Final, February 2005 C-5 ISCORS Technical Report 2004-03

Table C.3 Element Partitioning Assumptions Used by Aaberg et al. (1995a)

Element Fly Ash Slag Stack

H 0.1 0 0.9

Be 0.1 0.9 0.001

C 0.02 0.03 0.95

Na 0.1 0.9 0.001

P 0.13 0.85 0.02

S 0.65 0.3 0.05

Sc 0.05 0.95 0.0005

V 0.1 0.9 0.001

Cr 0.35 0.65 0.002

Mn 0.35 0.65 0.002

Fe 0.45 0.55 0.005

Co 0.34 0.65 0.01

Ni 0.4 0.6 0.005

Zn 0.49 0.5 0.01

Ge 0.5 0.5 0.001

As 0.5 0.5 0.005

Se 0.8 0.1 0.1

Sr 0.05 0.95 0.0001

Y 0.05 0.95 0.0005

Zr 0.05 0.95 0.0005

Nb 0.05 0.95 0.001

Tc 0.5 0.4 0.1

Ru 0.59 0.4 0.01

Ag 0.2 0.8 0.001

Sn 0.02 0.98 0.001

Sb 0.43 0.55 0.02
ISCORS Technical Report 2004-03 C-6 Final, February 2005

Table C.3 Element Partitioning Assumptions Used by Aaberg et al. (1995a)

(continued)

Element Fly Ash Slag Stack

Te 0.49 0.5 0.01

I 0.68 0.02 0.3

Cs 0.2 0.8 0.002

Ce 0.05 0.95 0.001

Pm 0.05 0.95 0.001

Sm 0.05 0.95 0.001

Eu 0.05 0.95 0.001

Hg 0.9 0.05 0.05

Bi 0.7 0.3 0.005

Ra 0.1 0.9 0.0005

Th 0.02 0.98 0.0005

U 0.02 0.98 0.0005

Np 0.02 0.98 0.0005

Pu 0.02 0.98 0.0005

Am 0.02 0.98 0.0005
Final, February 2005 C-7 ISCORS Technical Report 2004-03

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 ACERC1 SWIFT2 EPA IRF3 APTUS4

Ag 24-93 90-96

As 80-99 70-97 24-75

Ba 98-99 70-98 97-98

Be 99-100

Bi 70-72 98-99

Ca 0-100

Cd 18-45 8-34 22-91 81-94

Cr 25-58 96-99 68-91 99-100

Cu 75-99 88-93

Hg 0 for all runs 31-92 16-27

Mg 99-100 99-100

Mn 98-99

Ni 98-99 88-129 99-100

Pb 22-62 13-62 35-99 17-18

Sb 98-100 46-53

Se 93-99

Sr 99 for two runs 80-87

Te 100 for two runs

Tl 13-29 30-98

Zn 48-98 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.
ISCORS Technical Report 2004-03 C-8 Final, February 2005

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 SWIFT1 EPA IRF2 APTUS3

Ag 7-100 4-9

As 1-100 5-30 25-77

Ba 1-100 3-11 2-3

Be 0-1

Bi 28-30 (2 runs) 1-2

Ca 0-100

Cd 74-100 9-78 6-18

Cr 1-100 9-32 0-1

Cu 1-15 8-11

Hg 100 for all runs 7-97 73-84

Mg 0.07-0.2 (2 runs) 0-1

Mn 1-2

Ni 1-100 11-30 (2 runs) 0-1

Pb 38-100 1-65 81-82

Sb 0-100 47-54

Se 0-7

Sr 0.3-0.6 (2 runs) 13-19

Te 0 (both runs)

Tl 71-100 1-69

Zn 1-5 (2 runs) 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.
Final, February 2005 C-9 ISCORS Technical Report 2004-03

Table C.6 Average Control Efficiencies for the Easterly, Southerly, and

Westerly Incinerators

Plant Arsenic Cadmium Chromium Lead Nickel

Easterly 0.9174 0.8920 0.9476 0.9446 0.9647

Southerly 0.9951 0.9570 0.9992 0.9981 0.9984

Westerly 0.9787 0.9401 0.9994 0.9734 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-1-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.
ISCORS Technical Report 2004-03 C-10 Final, February 2005

Wild, R.E., O.I. Oztunali, J.J. Clancy, C.J. 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.
Appendix D

Conversion Between Radon Doses and

Working Level Concentrations

Final, February 2005 D-1 ISCORS Technical Report 2004-03

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:

Dmrem CEDE = DWLM × [Conversion Factor] (D.1)

with the conversion factors listed in Table D.1.

Table D.1 Radon Dosimetry Conversions Used in RESRAD and RESRAD-BUILD

Radon Isotope Indoor or Outdoor Conversion Factor 

(mrem CEDE per WLM)

Rn-220 Indoor 150

Outdoor 250

Rn-222 Indoor 760

Outdoor 570

The conversion between dose in WLM and the concentrations of radon progeny in Working

Levels (WL) is given by the Equation D.2:

DWLM = 51.5 × time fraction × CWL (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.1). 

Table D.2 Time Fractions and WL to WLM Conversion Factors

Scenario Indoor or Outdoor Time Fraction Conversion Factor

(WLM per WL)

Onsite Resident Indoor 0.651 33.5

Outdoor 0.25 12.9

POTW Loading Worker Indoor 0.228 11.7
1 The motivation for the (constant + 8x)

–1 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

The conversion from dose to pCi/l 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 × 10-3 WL per pCi Rn-222/L. For the POTW Loading Worker, the conversion factor may

range from 0.5 × 10-3 ~ 3 × 10-3 WL per pCi/l 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 Rn-220/l per pCi/g Th-228 . 720 × (45 + 8x)

–1 rsludge Asludge / Vroom (D.3)

CSRpCi Rn-222/l per pCi/g Ra-226 . 1.49 × (0.008 + 8x)

–1 rsludge Vsludge / Vroom (D.4)

Here 8x is the room air exchange rate in exchanges per hour, rsludge is the bulk density of the

sludge in grams per cubic cm, Vsludge is the total volume of sludge in the room in cubic meters,

and Vroom is the total volume of the room in cubic meters, and Asludge 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/l were derived from sensitivity analyses of the

baseline RESRAD-BUILD calculation:

CWL Rn-220 . CpCi Rn-220/l × 0.00417 × (1.25 hroom

–0.77 + 8x)

–1 (D.5)

CWL Rn-222 . CpCi Rn-222/l × 0.00625 × (2.69 hroom

–0.13 + 8x)

–1 (D.6)

where hroom is the height of the room in meters. 
Final, February 2005 D-3 ISCORS Technical Report 2004-03

Combining Equations D.3–D.6 leads to the following Concentration-to-Source-Ratios

(Equations D.7 and D.8):

CSRWL Rn-220 per pCi/g Th-228 . 3.00 × (45 + 8x)

–1 × (1.25 hroom

–0.77 + 8x)

–1 rsludge Asludge / Vroom (D.7)

CSRWL Rn-222 per pCi/g Ra-226 . 0.00931 × (0.008 + 8x)

–1 × (2.69 hroom–0.13 + 8x)–1 rsludge Vsludge / Vroom (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:

DSRWLM Rn-220 per pCi/g Th-228 . 17.6 × (45 + 8x)

–1 × (1.25 hroom–0.77 + 8x)–1 ×

(rsludge Asludge / Vroom) × (texp / 1000 hours) (D.9)

DSRWLM Rn-222 per pCi/g Ra-226 . 0.0547 × (0.008 + 8x)

–1 × (2.69 hroom–0.13 + 8x)–1 ×

(rsludge Asludge / Vroom) × (texp / 1000 hours) (D.10)

Finally, using Equation D.1 leads to the radon dose formulas (Equations D.11 and D.12):

DSRmrem(radon) per pCi/g Th-228 . 2640 × (45 + 8x)

–1 × (1.25 hroom–0.77 + 8x)–1 ×

(rsludge Asludge / Vroom) × (texp / 1000 hours) (D.11)

DSRmrem(radon) per pCi/g Ra-226 . 41.5 × (0.008 + 8x)

–1 × (2.69 hroom

–0.13 + 8x)

–1 ×

(rsludge Asludge / Vroom) × (texp / 1000 hours) (D.12)

These formulas can be used to estimate site-specific radon concentrations and doses for the

POTW Loading Worker scenario.

Appendix E

Probabilistic Percentiles for

Dose-to-Source Ratios

Final, February 2005 E-1 ISCORS Technical Report 2004-03

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.
ISCORS Technical Report 2004-03 E-2 Final, February 2005

Table E.1 Onsite Resident DSR Percentiles (mrem/yr per pCi/g in Sewage

Sludge)

Radionuclide 5% 10% 25% 50% 75% 90% 95% mean

Ac-227 3.64e-03 3.97e-03 4.67e-03 5.56e-03 6.87e-03 8.65e-03 1.06e-02 6.25e-03

Am-241 2.54e-04 2.93e-04 3.84e-04 5.26e-04 7.22e-04 1.07e-03 1.43e-03 7.60e-04

Be-7 7.44e-05 7.83e-05 8.70e-05 1.01e-04 1.21e-04 1.46e-04 1.63e-04 1.07e-04

C-14 3.18e-04 4.17e-04 7.07e-04 1.35e-03 3.45e-03 9.83e-03 2.42e-02 7.76e-03

Ce-141 5.51e-05 5.78e-05 6.40e-05 7.38e-05 8.83e-05 1.06e-04 1.19e-04 7.85e-05

Co-57 4.47e-04 4.76e-04 5.34e-04 6.24e-04 7.50e-04 9.13e-04 1.03e-03 6.66e-04

Co-60 1.78e-02 1.89e-02 2.13e-02 2.48e-02 2.98e-02 3.60e-02 4.06e-02 2.64e-02

Cr-51 2.41e-05 2.55e-05 2.83e-05 3.26e-05 3.91e-05 4.69e-05 5.26e-05 3.47e-05

Cs-134 1.13e-02 1.20e-02 1.35e-02 1.58e-02 1.93e-02 2.33e-02 2.63e-02 1.71e-02

Cs-137 5.07e-03 5.50e-03 6.27e-03 7.52e-03 9.36e-03 1.17e-02 1.35e-02 8.35e-03

Eu-154 8.49e-03 9.02e-03 1.00e-02 1.17e-02 1.40e-02 1.69e-02 1.88e-02 1.23e-02

Fe-59 1.57e-03 1.65e-03 1.84e-03 2.13e-03 2.55e-03 3.07e-03 3.43e-03 2.26e-03

H-3 1.35e-06 1.56e-06 2.10e-06 3.04e-06 5.08e-06 8.67e-06 1.20e-05 4.31e-06

I-125 4.75e-05 6.31e-05 9.88e-05 1.68e-04 2.86e-04 4.61e-04 6.09e-04 2.35e-04

I-131 1.13e-04 1.22e-04 1.40e-04 1.67e-04 2.04e-04 2.51e-04 2.79e-04 1.80e-04

In-111 5.46e-05 5.73e-05 6.34e-05 7.32e-05 8.76e-05 1.05e-04 1.18e-04 7.79e-05

K-40 1.05e-03 1.12e-03 1.25e-03 1.45e-03 1.75e-03 2.10e-03 2.34e-03 1.54e-03

La-138 2.22e-03 3.04e-03 6.55e-03 1.00e-02 1.27e-02 1.55e-02 1.78e-02 9.82e-03

Np-237 3.23e-03 4.12e-03 6.17e-03 1.11e-02 2.73e-02 1.03e-01 2.42e-01 6.26e-02

Pa-231 2.15e-03 3.11e-03 5.37e-03 8.79e-03 1.54e-02 3.06e-02 4.75e-02 1.62e-02

Pb-210 1.93e-03 2.50e-03 3.82e-03 5.93e-03 9.72e-03 1.50e-02 1.88e-02 7.73e-03

Po-210 3.03e-04 4.16e-04 7.18e-04 1.34e-03 2.59e-03 4.44e-03 6.13e-03 2.06e-03

Pu-238 1.76e-04 2.15e-04 3.02e-04 4.41e-04 6.34e-04 9.11e-04 1.23e-03 5.45e-04

Pu-239 1.99e-04 2.40e-04 3.39e-04 4.92e-04 7.16e-04 1.02e-03 1.35e-03 6.37e-04

Ra-226 1.65e-01 1.67e-01 1.69e-01 1.74e-01 1.80e-01 1.87e-01 1.94e-01 1.76e-01

Ra-228 1.45e-02 1.55e-02 1.75e-02 2.05e-02 2.46e-02 3.09e-02 3.55e-02 2.24e-02

Sm-153 4.62e-06 4.85e-06 5.36e-06 6.19e-06 7.38e-06 8.88e-06 9.93e-06 6.57e-06

Sr-89 1.46e-05 1.86e-05 3.21e-05 6.41e-05 1.34e-04 2.66e-04 4.11e-04 1.29e-04

Sr-90 9.00e-04 1.25e-03 2.34e-03 4.90e-03 1.04e-02 2.13e-02 3.23e-02 1.01e-02

Th-228 1.19e-02 1.25e-02 1.36e-02 1.55e-02 1.80e-02 2.13e-02 2.36e-02 1.62e-02

Th-229 2.54e-03 2.73e-03 3.10e-03 3.58e-03 4.27e-03 5.10e-03 5.71e-03 3.87e-03

Th-230 9.18e-04 2.88e-03 1.28e-02 3.63e-02 5.37e-02 6.01e-02 6.24e-02 3.37e-02

Th-232 1.35e-02 2.06e-02 2.64e-02 3.17e-02 3.82e-02 4.68e-02 5.28e-02 3.30e-02

Tl-201 8.44e-06 8.88e-06 9.91e-06 1.15e-05 1.38e-05 1.67e-05 1.88e-05 1.23e-05

Tl-202 1.57e-04 1.66e-04 1.85e-04 2.13e-04 2.56e-04 3.10e-04 3.45e-04 2.28e-04

U-233 5.77e-05 7.58e-05 1.17e-04 2.06e-04 3.76e-04 6.24e-04 1.09e-03 5.76e-04

U-234 5.30e-05 7.09e-05 1.13e-04 1.95e-04 3.34e-04 5.85e-04 1.02e-03 5.23e-04

U-235 8.61e-04 1.09e-03 1.28e-03 1.51e-03 1.82e-03 2.21e-03 2.53e-03 1.73e-03

U-238 2.13e-04 2.54e-04 3.07e-04 3.83e-04 4.94e-04 6.76e-04 1.00e-03 7.07e-04

Xe-131m 1.11e-06 1.19e-06 1.34e-06 1.55e-06 1.86e-06 2.25e-06 2.53e-06 1.65e-06

Zn-65 3.36e-03 3.82e-03 4.68e-03 6.08e-03 8.63e-03 1.40e-02 2.07e-02 8.34e-03
Final, February 2005 E-3 ISCORS Technical Report 2004-03

Table E.2 Recreational User DSR Percentiles (mrem/yr per pCi/g in Sewage

Sludge)

Radionuclide 5% 10% 25% 50% 75% 90% 95% mean

Ac-227 1.96E-03 2.05E-03 2.10E-03 2.15E-03 2.21E-03 2.29E-03 2.35E-03 2.17E-03

Am-241 1.53E-04 1.56E-04 1.59E-04 1.63E-04 1.68E-04 1.74E-04 1.82E-04 8.00E-04

Be-7 4.42E-05 4.53E-05 4.58E-05 4.58E-05 4.58E-05 4.58E-05 4.58E-05 4.55E-05

C-14 1.75E-04 2.28E-04 4.06E-04 9.30E-04 5.03E-03 3.81E-02 9.76E-02 2.56E-02

Ce-141 3.32E-05 3.33E-05 3.33E-05 3.33E-05 3.33E-05 3.33E-05 3.33E-05 3.33E-05

Co-57 2.45E-04 2.60E-04 2.67E-04 2.68E-04 2.70E-04 2.72E-04 2.76E-04 2.66E-04

Co-60 9.61E-03 1.04E-02 1.07E-02 1.08E-02 1.08E-02 1.09E-02 1.10E-02 1.06E-02

Cr-51 1.39E-05 1.44E-05 1.48E-05 1.48E-05 1.49E-05 1.49E-05 1.49E-05 1.47E-05

Cs-134 5.88E-03 6.02E-03 6.07E-03 6.11E-03 6.18E-03 6.30E-03 6.41E-03 6.12E-03

Cs-137 2.52E-03 2.56E-03 2.58E-03 2.62E-03 2.68E-03 2.77E-03 2.86E-03 2.64E-03

Eu-154 4.89E-03 5.19E-03 5.33E-03 5.36E-03 5.36E-03 5.36E-03 5.36E-03 5.26E-03

Fe-59 9.16E-04 9.47E-04 9.63E-04 9.66E-04 9.66E-04 9.67E-04 9.67E-04 9.56E-04

H-3 3.83E-07 4.72E-07 6.84E-07 1.13E-06 2.03E-06 3.40E-06 4.51E-06 1.64E-06

I-125 6.31E-06 7.45E-06 9.74E-06 1.36E-05 1.92E-05 2.73E-05 3.33E-05 1.62E-05

I-131 5.47E-05 5.59E-05 5.72E-05 5.81E-05 5.94E-05 6.10E-05 6.23E-05 5.84E-05

In-111 3.30E-05 3.30E-05 3.30E-05 3.30E-05 3.30E-05 3.30E-05 3.30E-05 3.30E-05

K-40 6.02E-04 6.24E-04 6.58E-04 6.83E-04 7.01E-04 7.12E-04 7.17E-04 6.75E-04

La-138 1.38E-03 1.84E-03 3.56E-03 5.23E-03 5.56E-03 5.59E-03 5.60E-03 4.66E-03

Np-237 8.15E-04 9.89E-04 1.10E-03 1.37E-03 3.48E-02 2.51E-01 6.07E-01 1.58E-01

Pa-231 4.58E-04 5.39E-04 1.05E-03 2.00E-03 2.54E-03 2.84E-03 1.05E-02 1.06E-02

Pb-210 2.79E-04 2.98E-04 3.42E-04 4.21E-04 5.39E-04 6.83E-04 8.28E-04 4.72E-04

Po-210 5.34E-05 6.23E-05 8.70E-05 1.31E-04 2.10E-04 3.22E-04 4.15E-04 1.70E-04

Pu-238 1.07E-04 1.09E-04 1.11E-04 1.15E-04 1.20E-04 1.25E-04 1.29E-04 1.17E-04

Pu-239 1.19E-04 1.21E-04 1.24E-04 1.28E-04 1.33E-04 1.40E-04 1.45E-04 1.79E-04

Ra-226 8.18E-03 8.19E-03 8.24E-03 8.31E-03 8.43E-03 8.58E-03 8.72E-03 8.53E-03

Ra-228 6.88E-03 7.05E-03 7.12E-03 7.18E-03 7.24E-03 7.32E-03 7.37E-03 7.15E-03

Sm-153 2.75E-06 2.75E-06 2.75E-06 2.76E-06 2.76E-06 2.76E-06 2.77E-06 2.76E-06

Sr-89 1.85E-06 2.02E-06 2.43E-06 3.34E-06 5.46E-06 9.89E-06 1.51E-05 5.38E-06

Sr-90 5.61E-05 7.04E-05 1.05E-04 1.84E-04 3.86E-04 8.41E-04 1.45E-03 7.68E-04

Th-228 6.14E-03 6.21E-03 6.26E-03 6.32E-03 6.38E-03 6.46E-03 6.51E-03 6.29E-03

Th-229 1.39E-03 1.40E-03 1.42E-03 1.44E-03 1.46E-03 1.50E-03 1.52E-03 1.93E-03

Th-230 6.53E-05 2.06E-04 8.15E-04 2.09E-03 2.75E-03 2.97E-03 3.05E-03 1.96E-03

Th-232 5.80E-03 8.35E-03 1.10E-02 1.19E-02 1.21E-02 1.23E-02 1.24E-02 1.13E-02

Tl-201 4.90E-06 4.90E-06 4.90E-06 4.91E-06 4.93E-06 4.97E-06 5.01E-06 4.93E-06

Tl-202 8.90E-05 9.20E-05 9.42E-05 9.45E-05 9.46E-05 9.50E-05 9.54E-05 9.38E-05

U-233 1.30E-05 1.49E-05 1.93E-05 3.62E-05 1.24E-04 3.68E-04 1.96E-03 7.66E-04

U-234 1.19E-05 1.32E-05 1.58E-05 2.10E-05 3.14E-05 2.39E-04 1.34E-03 9.51E-04

U-235 4.42E-04 5.58E-04 6.17E-04 6.27E-04 6.35E-04 8.02E-04 2.15E-03 1.39E-03

U-238 8.50E-05 1.07E-04 1.15E-04 1.19E-04 1.26E-04 2.62E-04 1.23E-03 1.33E-03

Xe-131m 6.38E-07 6.61E-07 6.97E-07 7.42E-07 7.78E-07 8.05E-07 8.19E-07 7.36E-07

Zn-65 1.31E-03 1.65E-03 1.71E-03 1.77E-03 1.89E-03 2.13E-03 2.35E-03 1.82E-03
ISCORS Technical Report 2004-03 E-4 Final, February 2005

Table E.3 Nearby Town DSR Percentiles (mrem/yr per pCi/g in Sewage Sludge)

(One Year of Application)

Radionuclide 5% 10% 25% 50% 75% 90% 95% mean

Ac-227 9.55e-06 1.17e-05 1.69e-05 2.45e-05 3.31e-05 4.96e-05 5.94e-05 2.74e-05

Am-241 6.62e-07 8.12e-07 1.18e-06 1.68e-06 2.27e-06 3.49e-06 4.22e-06 1.90e-06

Be-7 8.82e-13 1.06e-12 1.50e-12 2.27e-12 3.29e-12 4.66e-12 6.43e-12 2.76e-12

C-14 2.55e-07 2.79e-07 3.28e-07 3.83e-07 4.42e-07 4.96e-07 5.22e-07 3.86e-07

Ce-141 1.70e-11 2.01e-11 2.67e-11 3.96e-11 5.56e-11 6.59e-11 7.12e-11 4.15e-11

Co-57 2.34e-11 2.94e-11 4.56e-11 7.33e-11 1.17e-10 2.01e-10 2.98e-10 1.00e-10

Co-60 1.42e-09 1.83e-09 2.73e-09 4.21e-09 6.63e-09 1.02e-08 1.36e-08 5.53e-09

Cr-51 1.99e-12 2.48e-12 3.82e-12 6.08e-12 9.49e-12 1.45e-11 1.80e-11 7.41e-12

Cs-134 1.52e-09 1.97e-09 3.05e-09 5.27e-09 9.93e-09 1.91e-08 2.84e-08 8.80e-09

Cs-137 2.87e-09 3.63e-09 5.50e-09 8.80e-09 1.49e-08 2.71e-08 4.28e-08 1.42e-08

Eu-154 9.18e-10 1.19e-09 1.78e-09 2.72e-09 4.13e-09 5.94e-09 7.50e-09 3.24e-09

Fe-59 8.27e-11 1.03e-10 1.63e-10 2.59e-10 4.16e-10 6.10e-10 7.44e-10 3.19e-10

H-3 1.37e-07 1.63e-07 2.05e-07 2.79e-07 3.65e-07 4.64e-07 5.32e-07 2.97e-07

I-125 1.80e-09 2.21e-09 3.27e-09 5.31e-09 8.46e-09 1.25e-08 1.55e-08 6.54e-09

I-131 2.46e-09 3.03e-09 4.48e-09 7.27e-09 1.16e-08 1.72e-08 2.12e-08 8.96e-09

In-111 5.86e-12 7.00e-12 1.03e-11 1.63e-11 2.41e-11 3.56e-11 4.54e-11 2.00e-11

K-40 5.78e-11 7.01e-11 1.07e-10 1.62e-10 2.42e-10 3.64e-10 4.94e-10 1.99e-10

La-138 1.83e-09 2.24e-09 3.27e-09 5.20e-09 8.20e-09 1.68e-08 2.69e-08 9.74e-09

Np-237 7.36e-07 8.89e-07 1.28e-06 1.96e-06 2.69e-06 3.88e-06 5.00e-06 3.10e-06

Pa-231 2.99e-06 4.50e-06 8.19e-06 1.59e-05 2.74e-05 4.16e-05 5.30e-05 2.02e-05

Pb-210 6.67e-08 8.06e-08 1.16e-07 1.65e-07 2.22e-07 3.28e-07 4.04e-07 1.86e-07

Po-210 2.00e-08 2.36e-08 3.12e-08 4.67e-08 6.50e-08 8.22e-08 9.68e-08 5.13e-08

Pu-238 5.97e-07 7.42e-07 1.05e-06 1.53e-06 2.08e-06 3.00e-06 3.62e-06 1.71e-06

Pu-239 6.79e-07 8.29e-07 1.17e-06 1.67e-06 2.28e-06 3.40e-06 3.95e-06 1.88e-06

Ra-226 1.19e-04 1.19e-04 1.19e-04 1.19e-04 1.19e-04 1.19e-04 1.19e-04 1.19e-04

Ra-228 1.72e-04 1.87e-04 1.93e-04 1.95e-04 1.96e-04 1.96e-04 1.96e-04 1.90e-04

Sm-153 1.15e-11 1.36e-11 1.97e-11 2.94e-11 4.30e-11 5.83e-11 7.39e-11 3.44e-11

Sr-89 1.14e-10 1.31e-10 1.86e-10 2.75e-10 3.88e-10 5.02e-10 5.70e-10 3.00e-10

Sr-90 3.77e-09 4.92e-09 7.81e-09 1.23e-08 2.15e-08 4.05e-08 5.76e-08 1.99e-08

Th-228 3.39e-04 3.39e-04 3.39e-04 3.40e-04 3.40e-04 3.40e-04 3.41e-04 3.40e-04

Th-229 3.22e-06 3.97e-06 5.60e-06 8.40e-06 1.15e-05 1.63e-05 1.92e-05 9.27e-06

Th-230 1.46e-06 2.52e-06 8.69e-06 2.50e-05 3.76e-05 4.17e-05 4.30e-05 2.34e-05

Th-232 1.17e-04 2.00e-04 2.99e-04 3.35e-04 3.43e-04 3.47e-04 3.51e-04 3.02e-04

Tl-201 2.77e-12 3.47e-12 5.36e-12 9.30e-12 1.66e-11 2.99e-11 4.49e-11 1.45e-11

Tl-202 1.32e-11 1.67e-11 2.59e-11 4.51e-11 8.07e-11 1.46e-10 2.19e-10 7.06e-11

U-233 1.95e-07 2.44e-07 3.67e-07 5.44e-07 7.90e-07 1.19e-06 1.50e-06 6.46e-07

U-234 1.86e-07 2.30e-07 3.27e-07 4.82e-07 6.59e-07 9.41e-07 1.15e-06 5.39e-07

U-235 1.76e-07 2.22e-07 3.17e-07 4.65e-07 6.44e-07 9.77e-07 1.19e-06 5.43e-07

U-238 1.68e-07 2.03e-07 2.95e-07 4.34e-07 5.82e-07 8.77e-07 1.04e-06 4.84e-07

Xe-131m 00000000

Zn-65 4.69e-10 6.16e-10 1.04e-09 1.70e-09 2.94e-09 4.57e-09 5.64e-09 2.23e-09
Final, February 2005 E-5 ISCORS Technical Report 2004-03

Table E.4a Landfill (Municipal Solid Waste) Neighbor (mrem/yr per pCi/g in

Sewage Sludge)

Radionuclide 5% 10% 25% 50% 75% 90% 95% mean

Ac-227 4.16e-13 7.69e-12 1.86e-11 2.47e-11 3.08e-11 3.76e-11 4.77e-11 1.28e-10

Am-241 2.01e-07 1.44e-06 2.50e-06 4.01e-06 7.92e-06 1.85e-05 3.72e-05 1.04e-05

Be-7 0 0 0 0 0 0 0 0

C-14 0 0 0 0 0 1.30e-07 4.81e-05 1.12e-04

Ce-141 0 0 0 0 0 0 0 0

Co-57 0 0 0 0 0 0 0 0

Co-60 2.78e-33 3.19e-32 9.99e-32 2.67e-31 7.45e-31 1.72e-30 2.95e-30 1.45e-23

Cr-51 0 0 0 0 0 0 0 0

Cs-134 0 0 0 0 0 0 0 8.14e-41

Cs-137 2.50e-12 7.30e-12 1.87e-11 4.36e-11 9.74e-11 1.88e-10 2.76e-10 3.78e-10

Eu-154 6.55e-25 1.04e-23 2.26e-23 3.65e-23 7.99e-23 1.71e-22 2.70e-22 2.15e-17

Fe-59 0 0 0 0 0 0 0 0

H-3 0 0 0 3.30e-21 1.91e-11 3.54e-08 3.01e-07 6.59e-08

I-125 0 0 0 0 0 0 0 0

I-131 0 0 0 0 0 0 0 0

In-111 0 0 0 0 0 0 0 0

K-40 7.43e-14 3.96e-13 4.80e-12 5.68e-11 4.32e-10 8.26e-07 9.19e-06 1.32e-06

La-138 1.88e-36 1.07e-27 1.36e-14 5.36e-09 7.23e-08 4.88e-05 7.72e-04 1.99e-04

Np-237 2.87e-10 8.81e-10 2.68e-07 6.69e-06 2.56e-05 1.53e-02 1.37e-01 3.22e-02

Pa-231 7.46e-09 2.69e-06 6.13e-05 1.18e-04 1.59e-04 2.01e-04 2.44e-04 1.68e-03

Pb-210 3.12e-12 5.60e-12 1.39e-11 3.51e-11 8.52e-11 1.74e-10 2.54e-10 7.27e-11

Po-210 0 0 0 0 0 0 0 0

Pu-238 4.27e-08 5.29e-08 6.80e-08 9.48e-08 1.74e-07 3.27e-07 5.10e-07 1.79e-07

Pu-239 4.80e-06 6.10e-06 8.27e-06 1.21e-05 2.10e-05 3.80e-05 5.58e-05 1.88e-05

Ra-226 1.27e-03 1.32e-03 1.36e-03 1.40e-03 1.49e-03 1.67e-03 1.95e-03 1.47e-03

Ra-228 5.33e-28 6.12e-28 8.13e-28 1.25e-27 2.26e-27 4.17e-27 5.93e-27 1.97e-27

Sm-153 0 0 0 0 0 0 0 0

Sr-89 0 0 0 0 0 0 0 0

Sr-90 2.57e-18 1.25e-15 3.62e-13 2.07e-12 5.84e-12 1.40e-11 3.06e-11 1.08e-08

Th-228 0 0 0 0 0 0 0 0

Th-229 6.31e-06 2.29e-05 3.43e-05 4.67e-05 7.97e-05 1.15e-04 2.25e-04 7.34e-05

Th-230 2.11e-04 3.77e-04 5.64e-04 6.01e-04 6.55e-04 7.78e-04 8.95e-04 6.04e-04

Th-232 1.52e-03 4.81e-03 7.41e-03 7.74e-03 7.78e-03 7.85e-03 7.93e-03 7.01e-03

Tl-201 0 0 0 0 0 0 0 0

Tl-202 0 0 0 0 0 0 0 0

U-233 2.15e-07 4.19e-07 1.79e-06 5.29e-06 8.46e-06 1.46e-05 2.46e-05 1.46e-04

U-234 2.55e-07 4.20e-07 1.57e-06 4.16e-06 5.35e-06 6.28e-06 7.32e-06 4.52e-05

U-235 9.70e-08 1.87e-07 1.03e-06 3.12e-06 4.95e-06 6.64e-06 8.23e-06 1.38e-04

U-238 4.21e-10 1.13e-09 3.08e-07 1.44e-06 2.07e-06 2.65e-06 3.71e-06 3.70e-05

Xe-131m 00000000

Zn-65 0 0 0 0 0 0 0 0
ISCORS Technical Report 2004-03 E-6 Final, February 2005

Table E.4b Landfill (Surface Impoundment) Neighbor (mrem/yr per pCi/g in

Sewage Sludge)

Radionuclide 5% 10% 25% 50% 75% 90% 95% mean

Ac-227 4.63e-11 4.77e-10 9.67e-10 1.24e-09 1.57e-09 1.95e-09 2.48e-09 3.75e-08

Am-241 2.09e-05 7.07e-05 1.04e-04 1.58e-04 3.11e-04 7.95e-04 1.90e-03 4.88e-04

Be-7 0 0 0 0 0 0 0 0

C-14 1.45e-15 8.87e-13 8.83e-09 4.54e-08 2.41e-07 2.84e-05 6.02e-03 8.31e-03

Ce-141 0 0 0 0 0 0 0 0

Co-57 0 0 0 0 0 0 0 0

Co-60 4.15e-31 2.40e-30 6.15e-30 1.60e-29 3.78e-29 9.31e-29 1.68e-28 9.93e-25

Cr-51 0 0 0 0 0 0 0 0

Cs-134 0 0 0 0 0 0 0 0

Cs-137 2.20e-10 4.11e-10 1.04e-09 2.33e-09 5.26e-09 1.01e-08 1.39e-08 4.24e-09

Eu-154 1.48e-22 8.77e-22 1.59e-21 2.50e-21 4.52e-21 9.27e-21 1.42e-20 4.40e-21

Fe-59 0 0 0 0 0 0 0 0

H-3 2.03e-35 1.51e-32 2.14e-26 1.63e-18 3.04e-09 1.89e-06 1.66e-05 3.39e-06

I-125 0 0 0 0 0 0 0 0

I-131 0 0 0 0 0 0 0 0

In-111 0 0 0 0 0 0 0 0

K-40 2.01e-11 8.30e-11 7.43e-10 4.83e-09 2.32e-08 3.55e-05 4.26e-04 6.08e-05

La-138 7.26e-36 9.45e-24 1.06e-11 5.33e-07 4.63e-06 3.25e-03 4.45e-02 1.09e-02

Np-237 4.26e-08 1.07e-07 2.91e-05 3.42e-04 1.22e-03 1.13e+00 1.18e+01 2.51e+00

Pa-231 2.06e-06 2.01e-04 2.89e-03 4.88e-03 6.36e-03 8.38e-03 1.04e-02 3.80e-02

Pb-210 1.97e-10 3.18e-10 7.35e-10 1.82e-09 4.31e-09 9.18e-09 1.52e-08 3.96e-09

Po-210 0 0 0 0 0 0 0 0

Pu-238 2.20e-06 2.59e-06 3.32e-06 4.80e-06 8.55e-06 1.65e-05 2.52e-06 8.45e-06

Pu-239 1.90e-04 2.45e-04 3.31e-04 4.72e-04 8.47e-04 1.62e-03 2.37e-03 7.82e-04

Ra-226 6.60e-02 6.80e-02 6.98e-02 7.12e-02 7.49e-02 8.18e-02 8.88e-02 7.38e-02

Ra-228 2.67e-26 3.08e-26 4.14e-26 6.74e-26 1.18e-25 2.12e-25 3.24e-25 4.25e-21

Sm-153 0 0 0 0 0 0 0 0

Sr-89 0 0 0 0 0 0 0 0

Sr-90 2.72e-16 3.51e-13 3.39e-11 1.25e-10 3.29e-10 8.27e-10 1.58e-09 2.06e-05

Th-228 0 0 0 0 0 0 0 0

Th-229 3.73e-04 9.62e-04 1.41e-03 1.91e-03 3.07e-03 5.88e-03 9.45e-03 3.12e-03

Th-230 1.22e-02 2.28e-02 3.00e-02 3.15e-02 3.41e-02 3.87e-02 4.32e-02 3.13e-02

Th-232 1.32e-01 2.92e-01 3.87e-01 3.98e-01 4.00e-01 4.03e-01 4.06e-01 3.65e-01

Tl-201 0 0 0 0 0 0 0 0

Tl-202 0 0 0 0 0 0 0 0

U-233 8.89e-06 1.92e-05 9.35e-05 2.20e-04 3.36e-04 6.07e-04 9.33e-04 4.33e-03

U-234 1.43e-05 2.37e-05 8.87e-05 2.05e-04 2.53e-04 3.00e-04 3.41e-04 5.00e-04

U-235 1.50e-06 5.77e-06 4.76e-05 1.29e-04 2.01e-04 2.67e-04 3.36e-04 5.32e-03

U-238 3.77e-09 9.81e-08 1.71e-05 5.87e-05 8.27e-05 1.06e-04 1.38e-04 2.02e-03

Xe-131m 00000000

Zn-65 0 0 0 0 0 0 0 0
Final, February 2005 E-7 ISCORS Technical Report 2004-03

Table E.5 Incinerator Neighbor (mrem/yr per pCi/g in Sewage Sludge)

Radionuclide 5% 10% 25% 50% 75% 90% 95% mean

Ac-227 5.79e+00 6.35e+00 7.46e+00 8.71e+00 1.00e+01 1.12e+01 1.18e+01 8.76e+00

Am-241 3.94e-01 4.32e-01 5.06e-01 5.90e-01 6.79e-01 7.61e-01 7.99e-01 5.94e-01

Be-7 3.61e-07 3.88e-07 4.57e-07 5.63e-07 7.04e-07 9.04e-07 1.09e-06 6.15e-07

C-14 1.95e-07 2.14e-07 2.51e-07 2.92e-07 3.38e-07 3.79e-07 3.99e-07 2.95e-07

Ce-141 1.75e-06 1.86e-06 2.07e-06 2.33e-06 2.59e-06 2.86e-06 3.02e-06 2.35e-06

Co-57 1.90e-05 2.11e-05 2.57e-05 3.38e-05 4.94e-05 7.35e-05 1.02e-04 4.38e-05

Co-60 2.11e-03 2.38e-03 2.91e-03 3.82e-03 4.85e-03 6.50e-03 7.97e-03 4.29e-03

Cr-51 1.98e-07 2.24e-07 2.84e-07 3.82e-07 5.33e-07 7.21e-07 8.78e-07 4.37e-07

Cs-134 1.46e-03 1.66e-03 2.16e-03 2.96e-03 4.20e-03 5.56e-03 6.69e-03 3.40e-03

Cs-137 2.74e-03 3.26e-03 4.15e-03 5.57e-03 7.81e-03 1.11e-02 1.43e-02 6.68e-03

Eu-154 1.67e-03 1.80e-03 2.12e-03 2.61e-03 3.28e-03 3.92e-03 4.34e-03 2.74e-03

Fe-59 8.17e-05 9.29e-05 1.20e-04 1.60e-04 2.26e-04 2.96e-04 3.54e-04 1.82e-04

H-3 1.54e-06 1.70e-06 1.99e-06 2.32e-06 2.69e-06 3.01e-06 3.17e-06 2.34e-06

I-125 1.16e-02 1.37e-02 2.00e-02 2.99e-02 4.28e-02 5.86e-02 6.99e-02 3.36e-02

I-131 2.17e-03 2.56e-03 3.73e-03 5.57e-03 7.97e-03 1.09e-02 1.31e-02 6.26e-03

In-111 4.78e-08 5.19e-08 6.12e-08 7.79e-08 1.12e-07 1.78e-07 2.42e-07 1.04e-07

K-40 1.03e-04 1.25e-04 1.65e-04 2.27e-04 3.17e-04 4.16e-04 4.81e-04 2.51e-04

La-138 1.97e-03 2.23e-03 2.73e-03 3.84e-03 6.73e-03 9.14e-03 1.06e-02 4.94e-03

Np-237 4.92e-01 5.38e-01 6.28e-01 7.31e-01 8.45e-01 9.40e-01 9.93e-01 7.37e-01

Pa-231 1.17e+00 1.26e+00 1.48e+00 1.73e+00 1.99e+00 2.23e+00 2.35e+00 1.74e+00

Pb-210 2.46e-02 2.67e-02 2.98e-02 3.39e-02 3.86e-02 4.31e-02 4.74e-02 3.47e-02

Po-210 6.60e-03 7.15e-03 8.16e-03 9.58e-03 1.13e-02 1.41e-02 1.64e-02 1.02e-02

Pu-238 3.48e-01 3.79e-01 4.44e-01 5.18e-01 5.99e-01 6.70e-01 7.04e-01 5.22e-01

Pu-239 3.82e-01 4.17e-01 4.89e-01 5.70e-01 6.58e-01 7.36e-01 7.74e-01 5.74e-01

Ra-226 2.97e-02 3.21e-02 3.70e-02 4.44e-02 5.35e-02 7.03e-02 8.80e-02 4.90e-02

Ra-228 1.19e-02 1.27e-02 1.42e-02 1.63e-02 1.88e-02 2.21e-02 2.53e-02 1.72e-02

Sm-153 5.34e-08 5.81e-08 6.65e-08 7.97e-08 1.09e-07 1.56e-07 2.03e-07 9.83e-08

Sr-89 1.75e-05 1.91e-05 2.20e-05 2.70e-05 3.32e-05 4.12e-05 4.70e-05 2.88e-05

Sr-90 4.29e-03 5.13e-03 7.19e-03 1.11e-02 1.79e-02 2.91e-02 3.86e-02 1.50e-02

Th-228 2.56e-01 2.81e-01 3.30e-01 3.85e-01 4.44e-01 4.97e-01 5.23e-01 3.87e-01

Th-229 1.89e+00 2.08e+00 2.44e+00 2.85e+00 3.29e+00 3.68e+00 3.87e+00 2.86e+00

Th-230 2.85e-01 3.13e-01 3.68e-01 4.30e-01 4.96e-01 5.55e-01 5.85e-01 4.32e-01

Th-232 1.46e+00 1.60e+00 1.87e+00 2.18e+00 2.52e+00 2.82e+00 2.97e+00 2.20e+00

Tl-201 1.99e-08 2.32e-08 3.21e-08 5.12e-08 9.34e-08 1.61e-07 2.31e-07 8.11e-08

Tl-202 5.12e-07 5.93e-07 7.73e-07 1.15e-06 1.98e-06 3.36e-06 4.74e-06 1.75e-06

U-233 1.19e-01 1.30e-01 1.52e-01 1.78e-01 2.06e-01 2.30e-01 2.43e-01 1.79e-01

U-234 1.16e-01 1.27e-01 1.49e-01 1.74e-01 2.01e-01 2.25e-01 2.37e-01 1.75e-01

U-235 1.09e-01 1.19e-01 1.39e-01 1.63e-01 1.88e-01 2.10e-01 2.22e-01 1.64e-01

U-238 1.04e-01 1.14e-01 1.33e-01 1.56e-01 1.80e-01 2.01e-01 2.12e-01 1.57e-01

Xe-131m 00000000

Zn-65 3.06e-04 3.66e-04 5.30e-04 8.34e-04 1.28e-03 1.82e-03 2.28e-03 1.01e-03
ISCORS Technical Report 2004-03 E-8 Final, February 2005

Table E.6 Sludge Application Worker (mrem/yr per pCi/g in Sewage Sludge)

Radionuclide 5% 10% 25% 50% 75% 90% 95% mean

Ac-227 1.71e-03 1.90e-03 2.35e-03 3.17e-03 4.40e-03 6.18e-03 7.62e-03 3.68e-03

Am-241 5.08e-05 6.04e-05 8.89e-05 1.43e-04 2.32e-04 3.48e-04 4.42e-04 1.80e-04

Be-7 3.79e-05 3.93e-05 3.99e-05 3.99e-05 3.99e-05 4.00e-05 4.00e-05 3.95e-05

C-14 3.66e-08 4.26e-08 5.66e-08 8.05e-08 1.13e-07 1.47e-07 1.71e-07 8.93e-08

Ce-141 2.59e-05 2.60e-05 2.60e-05 2.60e-05 2.60e-05 2.60e-05 2.60e-05 2.60e-05

Co-57 1.81e-04 1.94e-04 2.02e-04 2.04e-04 2.05e-04 2.05e-04 2.05e-04 2.00e-04

Co-60 8.55e-03 9.28e-03 9.74e-03 9.85e-03 9.87e-03 9.87e-03 9.87e-03 9.61e-03

Cr-51 1.16e-05 1.22e-05 1.26e-05 1.27e-05 1.27e-05 1.27e-05 1.27e-05 1.25e-05

Cs-134 5.04e-03 5.22e-03 5.32e-03 5.35e-03 5.35e-03 5.35e-03 5.35e-03 5.29e-03

Cs-137 2.12e-03 2.19e-03 2.23e-03 2.25e-03 2.25e-03 2.25e-03 2.25e-03 2.22e-03

Eu-154 4.13e-03 4.54e-03 4.70e-03 4.73e-03 4.73e-03 4.73e-03 4.73e-03 4.62e-03

Fe-59 8.19e-04 8.57e-04 8.76e-04 8.80e-04 8.81e-04 8.81e-04 8.81e-04 8.69e-04

H-3 6.46e-08 7.67e-08 1.03e-07 1.49e-07 2.13e-07 2.85e-07 3.36e-07 1.68e-07

I-125 1.11e-07 1.32e-07 1.69e-07 1.95e-07 2.02e-07 2.04e-07 2.05e-07 1.80e-07

I-131 4.47e-05 4.61e-05 4.78e-05 4.87e-05 4.89e-05 4.90e-05 4.90e-05 4.80e-05

In-111 2.73e-05 2.73e-05 2.73e-05 2.73e-05 2.73e-05 2.73e-05 2.73e-05 2.73e-05

K-40 5.27e-04 5.50e-04 5.83e-04 6.11e-04 6.32e-04 6.45e-04 6.51e-04 6.03e-04

La-138 8.98e-04 1.23e-03 2.64e-03 4.56e-03 5.01e-03 5.07e-03 5.08e-03 3.78e-03

Np-237 3.88e-04 5.49e-04 7.41e-04 8.18e-04 9.25e-04 1.06e-03 1.17e-03 8.20e-04

Pa-231 3.27e-04 4.86e-04 1.02e-03 2.06e-03 3.40e-03 5.06e-03 6.41e-03 2.50e-03

Pb-210 4.46e-06 4.97e-06 6.38e-06 8.95e-06 1.31e-05 1.89e-05 2.34e-05 1.08e-05

Po-210 3.40e-07 4.46e-07 7.30e-07 1.24e-06 2.08e-06 3.22e-06 4.16e-06 1.62e-06

Pu-238 2.98e-05 3.91e-05 6.48e-05 1.11e-04 1.88e-04 2.91e-04 3.75e-04 1.46e-04

Pu-239 3.27e-05 4.24e-05 7.10e-05 1.25e-04 2.09e-04 3.24e-04 4.16e-04 1.59e-04

Ra-226 7.37e-03 7.38e-03 7.38e-03 7.39e-03 7.40e-03 7.41e-03 7.41e-03 7.39e-03

Ra-228 6.15e-03 6.37e-03 6.47e-03 6.53e-03 6.60e-03 6.68e-03 6.74e-03 6.49e-03

Sm-153 1.78e-06 1.78e-06 1.78e-06 1.78e-06 1.78e-06 1.78e-06 1.78e-06 1.78e-06

Sr-89 9.58e-07 1.04e-06 1.12e-06 1.14e-06 1.15e-06 1.15e-06 1.15e-06 1.11e-06

Sr-90 1.02e-05 1.25e-05 1.50e-05 1.58e-05 1.61e-05 1.64e-05 1.67e-05 1.51e-05

Th-228 5.68e-03 5.77e-03 5.84e-03 5.91e-03 6.01e-03 6.13e-03 6.23e-03 5.90e-03

Th-229 1.20e-03 1.25e-03 1.39e-03 1.66e-03 2.06e-03 2.68e-03 3.15e-03 1.84e-03

Th-230 1.00e-04 1.82e-04 5.47e-04 1.58e-03 2.31e-03 2.56e-03 2.63e-03 1.46e-03

Th-232 4.79e-03 7.32e-03 1.01e-02 1.10e-02 1.15e-02 1.20e-02 1.25e-02 1.03e-02

Tl-201 3.27e-06 3.28e-06 3.28e-06 3.28e-06 3.28e-06 3.28e-06 3.28e-06 3.28e-06

Tl-202 7.30e-05 7.71e-05 7.98e-05 8.03e-05 8.03e-05 8.03e-05 8.03e-05 7.92e-05

U-233 1.07e-05 1.51e-05 2.65e-05 5.22e-05 9.92e-05 1.58e-04 1.99e-04 7.34e-05

U-234 9.31e-06 1.23e-05 2.06e-05 3.64e-05 6.00e-05 9.50e-05 1.23e-04 4.70e-05

U-235 2.94e-04 4.19e-04 4.99e-04 5.17e-04 5.43e-04 5.79e-04 6.08e-04 5.05e-04

U-238 7.18e-05 8.93e-05 9.95e-05 1.14e-04 1.36e-04 1.67e-04 1.94e-04 1.21e-04

Xe-131m 3.37e-07 3.48e-07 3.70e-07 3.93e-07 4.12e-07 4.28e-07 4.35e-07 3.90e-07

Zn-65 9.59e-04 1.33e-03 1.50e-03 1.52e-03 1.52e-03 1.52e-03 1.52e-03 1.45e-03
Final, February 2005 E-9 ISCORS Technical Report 2004-03

Table E.7a POTW Worker: Biosolids Loading (mrem/yr per pCi/g in Sewage

Sludge)

Radionuclide 5% 10% 25% 50% 75% 90% 95% mean

Ac-227 8.50E-02 8.70E-02 9.45E-02 1.17E-01 1.77E-01 3.07E-01 4.05E-01 1.74E-01

Am-241 1.58E-03 1.72E-03 2.30E-03 3.85E-03 7.85E-03 1.74E-02 2.35E-02 7.75E-03

Be-7 1.23E-02 1.23E-02 1.23E-02 1.23E-02 1.23E-02 1.23E-02 1.23E-02 1.23E-02

C-14 4.39E-07 4.40E-07 4.42E-07 4.50E-07 4.72E-07 5.10E-07 5.60E-07 4.68E-07

Ce-141 1.25E-02 1.25E-02 1.25E-02 1.25E-02 1.25E-02 1.25E-02 1.25E-02 1.25E-02

Co-57 1.92E-02 1.92E-02 1.92E-02 1.92E-02 1.92E-02 1.92E-02 1.92E-02 1.92E-02

Co-60 7.00E-01 7.00E-01 7.00E-01 7.00E-01 7.00E-01 7.00E-01 7.00E-01 7.00E-01

Cr-51 7.40E-03 7.40E-03 7.40E-03 7.40E-03 7.40E-03 7.40E-03 7.40E-03 7.40E-03

Cs-134 4.07E-01 4.07E-01 4.07E-01 4.07E-01 4.07E-01 4.07E-01 4.07E-01 4.07E-01

Cs-137 1.46E-01 1.46E-01 1.46E-01 1.46E-01 1.46E-01 1.46E-01 1.46E-01 1.46E-01

Eu-154 3.32E-01 3.32E-01 3.32E-01 3.32E-01 3.32E-01 3.32E-01 3.32E-01 3.32E-01

Fe-59 3.31E-01 3.31E-01 3.31E-01 3.31E-01 3.31E-01 3.31E-01 3.31E-01 3.31E-01

H-3 7.05E-05 1.01E-04 1.64E-04 3.06E-04 5.85E-04 9.25E-04 1.33E-03 4.62E-04

I-125 6.00E-04 6.00E-04 6.00E-04 6.00E-04 6.00E-04 6.00E-04 6.00E-04 6.00E-04

I-131 9.20E-02 9.20E-02 9.20E-02 9.20E-02 9.20E-02 9.20E-02 9.20E-02 9.20E-02

In-111 8.05E-02 8.05E-02 8.05E-02 8.05E-02 8.05E-02 8.05E-02 8.05E-02 8.05E-02

K-40 4.53E-02 4.53E-02 4.53E-02 4.53E-02 4.53E-02 4.53E-02 4.53E-02 4.53E-02

La-138 3.45E-01 3.45E-01 3.45E-01 3.45E-01 3.45E-01 3.45E-01 3.46E-01 3.45E-01

Np-237 1.36E-04 2.98E-04 1.00E-03 2.83E-03 7.50E-03 1.77E-02 2.89E-02 7.50E-03

Pa-231 8.40E-03 8.75E-03 1.02E-02 1.51E-02 2.74E-02 4.90E-02 8.05E-02 2.57E-02

Pb-210 2.09E-04 2.16E-04 2.41E-04 3.23E-04 5.25E-04 9.50E-04 1.33E-03 5.00E-04

Po-210 4.39E-06 6.40E-06 1.62E-05 4.76E-05 1.23E-04 2.70E-04 4.35E-04 1.11E-04

Pu-238 9.60E-05 2.07E-04 6.55E-04 2.17E-03 5.75E-03 1.19E-02 1.80E-02 5.15E-03

Pu-239 9.45E-05 2.17E-04 7.55E-04 2.25E-03 6.20E-03 1.56E-02 2.38E-02 5.95E-03

Ra-228 2.59E-01 2.59E-01 2.59E-01 2.59E-01 2.59E-01 2.59E-01 2.59E-01 2.59E-01

Sm-153 5.80E-03 5.80E-03 5.80E-03 5.80E-03 5.80E-03 5.80E-03 5.80E-03 5.80E-03

Sr-89 3.93E-04 3.93E-04 3.93E-04 3.94E-04 3.94E-04 3.94E-04 3.95E-04 3.94E-04

Sr-90 9.85E-04 9.85E-04 9.90E-04 9.95E-04 1.01E-03 1.03E-03 1.05E-03 1.01E-03

Th-229 6.60E-02 6.70E-02 6.95E-02 7.75E-02 9.75E-02 1.39E-01 1.74E-01 9.50E-02

Th-230 1.18E-04 2.06E-04 5.85E-04 1.84E-03 4.97E-03 1.11E-02 1.68E-02 4.49E-03

Th-232 3.81E-04 8.75E-04 2.95E-03 8.80E-03 2.56E-02 5.60E-02 8.35E-02 2.21E-02

Tl-201 1.01E-02 1.01E-02 1.01E-02 1.01E-02 1.01E-02 1.01E-02 1.01E-02 1.01E-02

Tl-202 1.05E-01 1.05E-01 1.05E-01 1.05E-01 1.05E-01 1.05E-01 1.05E-01 1.05E-01

U-233 8.55E-05 1.24E-04 2.94E-04 7.60E-04 2.00E-03 4.97E-03 7.55E-03 1.93E-03

U-234 4.70E-05 8.50E-05 2.39E-04 7.75E-04 2.01E-03 4.17E-03 6.15E-03 1.80E-03

U-235 3.02E-02 3.02E-02 3.04E-02 3.08E-02 3.19E-02 3.42E-02 3.68E-02 3.19E-02

U-238 5.75E-03 5.75E-03 5.90E-03 6.35E-03 7.55E-03 9.55E-03 1.13E-02 7.25E-03

Xe-131m 8.75E-04 8.75E-04 8.75E-04 8.75E-04 8.75E-04 8.75E-04 8.75E-04 8.75E-04

Zn-65 1.60E-01 1.60E-01 1.60E-01 1.60E-01 1.60E-01 1.60E-01 1.60E-01 1.60E-01
ISCORS Technical Report 2004-03 E-10 Final, February 2005

Table E.7b POTW Worker: Biosolids Loading for Ra-226 and Combinations of Air

Exchange Rate and Building Height

air

exchange

rate 

(h-1)

room

height

(m) 5% 10% 25% 50% 75% 90% 95% mean

1.5 2 1.5 1.7 2.2 2.6 2.7 2.7 2.7 2.4

4 1.2 1.3 1.5 1.6 1.6 1.6 1.6 1.5

6 1.0 1.1 1.2 1.2 1.2 1.2 1.2 1.2

3 2 0.92 0.98 1.1 1.2 1.2 1.2 1.2 1.1

4 0.76 0.78 0.82 0.85 0.85 0.85 0.85 0.83

6 0.68 0.69 0.72 0.73 0.73 0.73 0.73 0.72

5 2 0.70 0.72 0.76 0.79 0.79 0.79 0.79 0.77

4 0.61 0.62 0.63 0.64 0.64 0.64 0.64 0.63

6 0.57 0.58 0.58 0.59 0.59 0.59 0.59 0.59

Table E.7c POTW Worker: Biosolids Loading for Th-228 and Combinations of Air

Exchange Rate and Building Height

air

exchange

rate 

(h-1)

room

height 

(m) 5% 10% 25% 50% 75% 90% 95% mean

1.5 2 6.4 7.8 12 17 18 18 18 15

4 4.9 5.6 7.6 9.1 9.4 9.4 9.4 8.3

6 4.0 4.5 5.5 6.3 6.4 6.4 6.4 5.9

3 2 4.8 5.6 7.5 8.9 9.2 9.3 9.3 8.2

4 3.4 3.7 4.3 4.8 4.8 4.9 4.9 4.5

6 2.6 2.8 3.1 3.3 3.4 3.4 3.4 3.2

5 2 3.7 4.0 4.9 5.5 5.6 5.6 5.6 5.2

4 2.4 2.6 2.8 3.0 3.0 3.0 3.0 2.9

6 1.9 1.9 2.1 2.1 2.2 2.2 2.2 2.1
Appendix F

Responses to Peer Review Comments

on ISCORS Dose Modeling Document

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-1 ISCORS Technical Report 2004-03

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?
ISCORS Technical Report 2004-03 F-2 Final, February 2005

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.
Final, February 2005 F-3 ISCORS Technical Report 2004-03

F.2 Positive Comments

The following general positive comments were provided by the peer reviewers that required no

response:

C The document uses generally accepted models and risk assessment tools. 

C The document is comprehensive/thorough.

C The answer to all three questions posed to the peer reviewers is “Yes.”

C The process was sound, scientifically reasonable, and complete.

C The report covers virtually every reasonably anticipated scenario and operational assumptions

for screening.

C The procedures were implemented in a systematic, scientific manner.

C The modeling approach is scientifically reasonable.

C The parameters/distributions and approach for characterizing uncertainty appear reasonable

and conservative.

C ISCORS adequately bounds the issue—the level of conservatism was generally appropriate.

C The scenarios are reasonable for screening.

C The report represents most major exposure situations.

C 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.

C 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

C 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.

C 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.
ISCORS Technical Report 2004-03 F-4 Final, February 2005

C 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.

C Comment: ISCORS should develop an executive summary for the dose modeling document.

Response: ISCORS included an executive summary in the final document.

C 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

C 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.

C 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. 

C 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.
Final, February 2005 F-5 ISCORS Technical Report 2004-03

C 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

C 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.

C 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

C Comment: ISCORS should base the assessment on a number of real-world sites, not on

generic or hypothetical locations, geology, hydrology, situations, and scenarios. 

C 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. 

C 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. 
ISCORS Technical Report 2004-03 F-6 Final, February 2005

F.3.2.4 Onsite Resident Scenario

C 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.

C 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. 

C 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

C 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 non-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

C 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

C 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
Final, February 2005 F-7 ISCORS Technical Report 2004-03

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.)

C 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.

C 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.

C 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

C 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.
ISCORS Technical Report 2004-03 F-8 Final, February 2005

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:

C Comment: The results of the TLD influent monitoring program (from Feb’96–Dec’00) for

Albuquerque, NM, might serve as a potential field validation site.

C Comment: The document should address empirical testing of at least all of the POTW

worker scenarios, including use of spiked samples and measured exposures.

C Comment: Some of the exposure scenarios, including all of the POTW worker scenarios, can

and should be tested.
BIBLIOGRAPHIC DATA SHEET

(See instructions on the reverse)

NRC FORM 335

(9-2004)

NRCMD 3.7

U.S. NUCLEAR REGULATORY COMMISSION 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

3. DATE REPORT PUBLISHED

MONTH

February

YEAR

2005

4. FIN OR GRANT NUMBER

2. TITLE AND SUBTITLE

ISCORS Assessment of Radioactivity in Sewage Sludge: Modeling to Assess Radiation Doses

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,

Division of Waste Management and Environmental Protection

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, 

same as above

provide name and mailing address.)

and mailing address.)

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.

14. SECURITY CLASSIFICATION

13. AVAILABILITY STATEMENT

unlimited

(This Page)

unclassified

(This Report)

unclassified

15. NUMBER OF PAGES

16. PRICE

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