Risk Assessment Revision for 

40 CPR Part 61 Subpart W – 

Radon Emissions from Operating Mill Tailings 

Task 3 – Risk Assessment Model 

Prepared by: 

S. Cohen & Associates 

1608 Spring Hill Road, Suite 400 

Vienna, VA 22182 

under 

Contract Number EP-D-10-042 

Work Assignment No. 1-06, Task 5 

Prepared for: 

U.S. Environmental Protection Agency 

Office of Radiation and Indoor Air 

1200 Pennsylvania Avenue, N.W. 

Washington, DC 20460 

Brian Littleton 

Work Assignment Manager 

August 31, 2010
WA 1-04, Task 3 i SC&A – August 31, 2010

TABLE OF CONTENTS 

Section Page

Executive Summary....................................................................................................................... iii

1.0 Introduction and Background ..............................................................................................1

2.0 Risk Assessment Models .....................................................................................................2

2.1 AIRDOS, AIRDOS-II, and AIRDOS-EPA .............................................................2

2.2 CAP88......................................................................................................................3

2.3 GENII with FRAMES..............................................................................................5

2.4 RESRAD-OFFSITE.................................................................................................7

2.5 MILDOS-AREA......................................................................................................9

2.6 MEPAS with FRAMES .........................................................................................12

2.7 AERMOD ..............................................................................................................12

2.8 GASPAR-II............................................................................................................13

2.9 GENII-NESHAPS..................................................................................................14

3.0 Detailed Model Evaluations...............................................................................................15

3.1 Evaluation Criteria.................................................................................................15

3.2 CAP88....................................................................................................................16

3.3 GENII with FRAMES............................................................................................20

3.4 RESRAD-OFFSITE...............................................................................................24

3.5 MILDOS-AREA....................................................................................................27

3.6 MEPAS with FRAMES .........................................................................................30

4.0 Results and Recommendations ..........................................................................................34

5.0 References..........................................................................................................................36
WA 1-04, Task 3 ii SC&A – August 31, 2010

LIST OF TABLES 

Table Page

Table 1. Evaluation Criteria......................................................................................................... 16

Table 2. Summary of Suitability Review for Five Codes Under Evaluation............................... 35
WA 1-04, Task 3 iii SC&A – August 31, 2010

EXECUTIVE SUMMARY 

The Office of Radiation and Indoor Air (ORIA) promulgated National Emissions Standards for 

Hazardous Air Pollutants (NESHAPs) for radon emissions from operating uranium mill tailings 

impoundments (Subpart W) on December 15, 1989. In support of Subpart W, as well as other 

portions of radiolonuclide NESHAP, ORIA published a Final Environmental Impact Statement 

(FEIS) and a three volume Background Information Document (BID), that provided 1) a detailed 

description of the Agency’s procedures and methods for estimating radiation dose and risk due to 

radionuclide emissions to the air, 2) detailed risk estimates for each source of emissions, and 

3) detailed economic assessments for each source of emissions. 

The purpose of this Work Assignment is to revise the risk assessment for the NESHAP for 

Radionuclides from uranium mill tailing facilities. The information developed in this Work 

Assignment will be used by the Agency in the determination of whether the existing standards 

for Subpart W need revising, and, if so, what may represent reasonable revisions to the standard. 

As documented in the BID, the FEIS used AIRDOS to calculate dose and risk to the public. This 

report reviews the appropriateness of using AIRDOS to calculate individual and population dose 

and risk. Currently available computer models have been reviewed to determine whether models 

other than AIRDOS exist for calculating dose and risk from the management of uranium 

byproduct materials from the processing of uranium ores. The atmospheric release risk 

assessment models reviewed for this Work Assignment were: 

● AIRDOS: The AIRDOS computer code was developed at Oak Ridge National 

Laboratory (ORNL) to estimate individual (rem/year) and population (man-rem/year) 

doses resulting from the atmospheric release of radionuclides from a nuclear facility. 

Atmospheric dispersion and surface deposition of released radionuclides are estimated as 

a function of direction and distance from a nuclear power plant or fuel-cycle facility, and 

doses to man through inhalation, air immersion, exposure to contaminated ground, food 

ingestion, and water immersion are estimated in the surrounding area. Radionuclide 

concentrations in food products are estimated from the output of the atmospheric 

transport model using the terrestrial transport model described in U.S. Nuclear 

Regulatory Commission (NRC) Regulatory Guide 1.109. Annual doses are estimated for 

total body, GI tract, bone, thyroid, lungs, muscle, kidneys, liver, spleen, testes, and 

ovaries. 

● CAP88: The CAP88 (which stands for Clean Air Act Assessment Package - 1988) 

computer model is a set of computer programs, databases and associated utility programs 

for estimation of dose and risk from radionuclide emissions to air. CAP88 is composed 

of modified versions of AIRDOS-EPA and DARTAB. CAP88-PC Version 3 

incorporates dose and risk factors from Federal Guidance Report 13. CAP88-PC is a 

U.S. Environmental Protection Agency (EPA) approved system for demonstrating 

compliance with 40 CFR 61 Subpart H, the Clean Air Act standard which applies to U.S. 

Department of Energy (DOE) facilities that emit radionuclides to air. EPA will provide 

the latest version of CAP88 to SC&A for evaluation, otherwise, SC&A will evaluate 

Revision 3, currently available from the EPA website: 

http://www.epa.gov/radiation/assessment/CAP88/. 
WA 1-04, Task 3 iv SC&A – August 31, 2010

● GENII: The GENII system, developed by the Pacific Northwest National Laboratory 

(PNNL), includes the capabilities for calculating radiation doses following chronic and 

acute releases. Radionuclide transport via air, water, or biological activity may be 

considered. Air transport options include both puff and plume models. Building wake 

effects can be included in acute atmospheric release scenarios. The code provides risk 

estimates for health effects to individuals or populations; these can be obtained using the 

code by applying appropriate risk factors to the effective dose equivalent or organ dose. 

In addition, GENII Version 2 uses cancer risk factors from Federal Guidance Report 13 

to estimate risk to specific organs or tissues. 

● RESRAD: RESRAD is a computer model developed by Argonne National Laboratory to 

estimate radiation doses and risks from RESidual RADioactive materials. Since 1989, 

RESRAD has been used widely by DOE, its operations and area offices, and its 

contractors for deriving limits for radionuclides in soil. RESRAD has also been used by 

EPA, U.S. Army Corps of Engineers, NRC, industrial firms, universities, and foreign 

government agencies and institutions. 

● MILDOS-AREA: The Argonne National Laboratory also developed MILDOS-AREA, a 

computer code that calculates the radiological dose commitments received by individuals 

and the general population within an 80-km radius of an operating uranium recovery 

facility. The transport of radiological emissions from point and different area sources is 

predicted with a sector-averaged Gaussian plume dispersion model. Mechanisms such as 

radioactive decay, plume depletion by deposition, in-growth of decay products, and 

resuspension of deposited radionuclides are included in the transport model. Alterations 

in operation throughout the facility's lifetime can be accounted for in the input stream. 

The exposure pathways considered are: inhalation; external exposure from groundshine 

and cloud immersion; and ingestion of vegetables, meat, and milk. Dose commitments 

are calculated primarily on the basis of the recommendations of the International 

Commission on Radiological Protection (ICRP). Only airborne releases of radioactive 

materials are considered in MILDOS-AREA; releases to surface water and to 

groundwater are not addressed in MILDOS-AREA. MILDOS-AREA is a multi-purpose 

code that can be used to evaluate population doses for NEPA assessments, maximum 

individual doses for predictive 40 CFR 190 compliance evaluations, or maximum offsite 

air concentrations for predictive evaluations of 10 CFR 20 compliance. 

● MEPAS: Multimedia Environmental Pollutant Assessment System (MEPAS), 

developed by the Pacific Northwest Laboratory (PNL), is a suite of integrated impact 

assessment software comprising physics-based fate and environmental transport models 

of air, soil, and water media. MEPAS simulates the release of contaminants from a 

source; transport through the air, groundwater, surface water, and/or overland pathways; 

and transfer through food chains and exposure pathways to the exposed individual or 

population. For human health impacts, risks are computed for carcinogens and hazard 

quotients for noncarcinogens. 

● AERMOD: AERMOD was developed by the AERMIC (American Meteorological 

Society (AMS)/U.S. Environmental Protection Agency (EPA) Regulatory Model 

Improvement Committee) as a state-of-the-practice Gaussian plume dispersion model 

whose formulation is based on planetary boundary layer principles. The AERMOD 

model utilizes a probability density function and the superposition of several Gaussian 
WA 1-04, Task 3 v SC&A – August 31, 2010

plumes to characterize the distinctly non-Gaussian nature of the vertical pollutant 

distribution for elevated plumes during convective conditions; otherwise the distribution 

is Gaussian. Also, nighttime urban boundary layers (and plumes within them) have the 

turbulence enhanced by AERMOD to simulate the influence of the urban heat island. 

The AERMOD model is applicable to rural and urban areas, flat and complex terrain, 

surface and elevated releases, and multiple sources (including point, area and volume 

sources). 

Each of the above computer models was described and discussed in detail, including the results 

of any benchmarks that were performed between the models. During this phase of the review, 

four of the models (AIRDOS, GASPAR, GENII-NESHAPS, and AERMOD) were eliminated 

from further evaluation. Next, a detailed evaluation of the remaining five atmospheric release 

risk assessment models was performed. The criteria used in the detailed evaluation are shown in 

Table ES-1. To account for the fact that not all of the criteria were considered to be of equal 

importance, weight factors were assigned to each of the criteria, as shown in Table ES-1. 

Table ES-1. Evaluation Criteria 

Evaluation Criteria Weight 

Factor 

Exposure Pathways Modeled 2 

Population Dose/Risk Capability 2 

Dose Factors Used 1.75 

Risk Factors Used 1.75 

Meteorological Data Processing 1.5 

Source Term Calculations 1.5 

Verification and Validation 1.25 

Ease of Use/User Friendly 1.25 

Documentation 1 

Sensitivity Analysis Capability 1 

Probabilistic Analysis Capability 1 

The results of the detailed evaluation are shown in Table ES-2. 

Table ES-2. Evaluation Results 

Evaluation Criteria Score 

RESRAD-OFFSITE 66.25 

CAP88 65.5 

GENII 61.75 

MEPAS 57 

MILDOS-AREA 48 

As Table ES-2 shows, RESRAD-OFFSITE was the highest scoring of the five codes, narrowly 

edging out CAP88. However, it is recommended that CAP88, and not RESRAD-OFFSITE, be 

used to perform the dose and risk calculations required for this Work Assignment. The reasons 

for this recommendation include: 
WA 1-04, Task 3 vi SC&A – August 31, 2010

• RESRAD-OFFSITE does not include the ability to perform population dose and risk 

estimates, which means that the RESRAD-OFFSITE results would need to be 

supplemented with population dose and risk estimates from another source. CAP88, on 

the other hand, is specifically designed to assess radiological emissions to the public. 

• The major area where CAP88 is lacking is sensitivity and probability analyses. For this 

Work Assignment, it is not anticipated that sensitivity or probability analysis will play a 

major role. 

• RESRAD-OFFSITE incorporates CAP88 air dispersion modeling, which means that 

there are no significant technical differences between the two codes for the purpose of 

this Work Assignment. 

• CAP88 was developed as a predecessor to AIRDOS which was the original code used in 

the evaluation of mill tailing impoundments during the development of the NESHAPs for 

radon emissions in 1989. 
WA 1-04, Task 3 1 SC&A – August 31, 2010

1.0 INTRODUCTION AND BACKGROUND 

The Office of Radiation and Indoor Air (ORIA) promulgated National Emissions Standards for 

Hazardous Air Pollutants (NESHAPs) for radon emissions from operating uranium mill tailings 

impoundments (Subpart W) on December 15, 1989. In support of Subpart W, as well as other 

portions of radiolonuclide NESHAPs, ORIA published a Final Environmental Impact Statement 

(FEIS) and a three volume Background Information Document (BID) that provided 1) a detailed 

description of the Agency’s procedures and methods for estimating radiation dose and risk due to 

radionuclide emissions to the air, 2) detailed risk estimates for each source of emissions, and 

3) detailed economic assessments for each source of emissions. 

The purpose of this Work Assignment is to revise the risk assessment for the NESHAPs for 

radionuclides from uranium mill tailing facilities. The information developed in this Work 

Assignment will be used by the Agency in the determination of whether the existing standards 

for Subpart W need revising, and, if so, what may represent reasonable revisions to the standard. 

As documented in the BID, the FEIS used AIRDOS to calculate dose and risk to the public. This 

report reviews the appropriateness of using AIRDOS to calculate individual and population dose 

and risk. Currently available computer models have been reviewed to determine whether models 

other than AIRDOS exist for calculating dose and risk from the management of uranium 

byproduct materials from the processing of uranium ores. The report examines the applicability 

of available models to evaluate radon emissions from operating mill tailings impoundments. By 

evaluating the various modeling codes against a set of predetermined criteria (outlined in 

Section 3), it will be determined which code is most suitable for the purposes of determining 

current dose and risk conditions at these operating sites. The modeling codes will be considered 

based on their applicability to the problem, whether current analytical methods are employed 

(such as dose and risk factors), the ability to process population and meteorological data, to what 

extent the code is documented/validated, and finally, how user friendly and intuitive the code is. 

The report is organized into three main sections (Sections 2-4): Section 2 provides a description 

of the computer models that were evaluated, Section 3 presents the evaluation criteria and results 

of the evaluation for the main codes selected, and the final section summarizes the results of the 

evaluation and recommends which code should be used for the individual and population dose 

and risk analysis, which will be performed as part of Task 4 of this Work Assignment. 
WA 1-04, Task 3 2 SC&A – August 31, 2010

2.0 RISK ASSESSMENT MODELS 

2.1 AIRDOS, AIRDOS-II, and AIRDOS-EPA 

The AIRDOS computer code was developed at Oak Ridge National Laboratory (ORNL) to 

estimate individual (rem/year) and population (man-rem/year) doses resulting from the 

atmospheric release of radionuclides from a nuclear facility. Atmospheric dispersion and surface 

deposition of released radionuclides are estimated as a function of direction and distance from a 

nuclear power plant or fuel-cycle facility, and doses to man through inhalation, air immersion, 

exposure to contaminated ground, food ingestion, and water immersion are estimated in the 

surrounding area. Radionuclide concentrations in food products are estimated from the output of 

the atmospheric transport model using the terrestrial transport model described in U.S. Nuclear 

Regulatory Commission (NRC) Regulatory Guide 1.109. Annual doses are estimated for total 

body, GI tract, bone, thyroid, lungs, muscle, kidneys, liver, spleen, testes, and ovaries. For 

additional information regarding the development of AIRDOS, refer to Moore 1975, Moore 

1977, and Moore, et al. 1979. 

Of particular interest to this Work Assignment, in 1978, the NRC used AIRDOS-II to perform a 

detailed analysis of the radiological impact of the Irigaray project of solution mining (in situ 

leaching) operations involving uranium ore deposits in Johnson County, Wyoming. The results 

of the NRC’s AIRDOS-II analysis are presented in the Final Environmental Statement for the 

Irigaray project (NUREG-0481). 

For the NESHAPs for Radionuclides, EIS risk assessment (EPA/520/1-89-005), EPA used 

AIRDOS-EPA to calculate environmental concentrations resulting from radionuclide emissions 

into air. The results of the AIRDOS-EPA analysis were estimates of air and ground surface 

radionuclide concentrations; intake rates via inhalation of air; and ingestion of radioactivity via 

meat, milk, and fresh vegetables. The AIRDOS-EPA calculated concentration and intake rates, 

as well as other parameters (such as particle size, respiratory clearance class, and gastrointestinal 

absorption factor), were passed on to the DARTAB computer program for dose and risk 

assessments. The DARTAB computer program provides an estimate of the impact of 

radionuclide emissions by combining information on the amounts of radionuclides inhaled 

and/or ingested with dosimetric and health effect data for a given quantity of each radionuclide. 

In addition to the AIRDOS-EPA provided data, the DARTAB NESHAPs for Radionuclides, EIS 

assessment utilized dosimetric and health effect data that were calculated by RADRISK. The 

RADRISK program calculates the dose rate to organs resulting from the inhalation or ingestion 

of a given quantity of a radionuclide. The organ dose rates are then processed by RESRAD to 

calculate the risk of fatal cancer to a cohort of people. For approximately 500 radionuclides, the 

calculated risks (i.e., the probability of premature death for a member of the cohort due to 

inhalation or ingestion of a given quantity of each radionuclide) are written to a data file by 

RADRISK so that they can be accessed by other computer programs (e.g., DARTAB). 

On October 31, 1989, under 40 CFR Part 61, NESHAPs, the EPA issued the final rules for 

radionuclide emissions to air. AIRDOS-EPA, DARTAB, and the RADRISK dose and risk 

factors were combined into the Clean Air Act Assessment Package-1988 (CAP88) and used to 
WA 1-04, Task 3 3 SC&A – August 31, 2010

generate risk estimates for the risk assessment supporting this rule. With the issuance of CAP88, 

AIRDOS-EPA, DARTAB, and RADRISK ceased to exist as standalone computer programs. 

CAP88 is discussed below. 

2.2 CAP88 

As stated above in the AIRDOS discussion, the CAP88 was developed in 1988 from the 

AIRDOS, RADRISK, and DARTAB computer programs. The initial version of CAP88 ran on 

large mainframe computers at ORNL, however, in the late 1980s, the EPA and the U.S. 

Department of Energy (DOE) began a cooperative project to produce a personal computer 

version of CAP88 — CAP88-PC, which was released in March 1992. CAP88 implements the 

NRC’s Regulatory Guide 1.109 methodology for calculating doses from the terrestrial food 

pathways. 

Among the modifications and enhancements made to CAP88 during its conversion to CAP88-PC 

include the fact that CAPP88-PC estimates risk as well as dose. CAP88-PC was modified to 

perform either “Radon-only” or “Non-Radon” runs, to conform to the format of the 1988 Clean 

Air Act NESHAPs Rulemaking. “Radon-only” assessments, which only have Rn-222 in the 

source term, automatically include working level calculations; all other source terms ignore 

working levels. Also, the organs and weighting factors are modified to follow the ICRP 26/30 

Effective Dose Equivalent calculations, which eliminates flexibility on specifying organs and 

weighting factors. In February 1992, CAP88-PC, Version 2.0 was approved for demonstrating 

compliance with 40 CFR Part 61 “Subpart H – National Emission Standards for Emissions of 

Radionuclides Other Than Radon from Department of Energy Facilities”. 

In March 2000, Version 2 of CAP88-PC was issued. CAP88-PC, Version 2 provided a 

framework for developing inputs to perform full-featured dose and risk assessments in a 

Windows environment, as well as some minor changes to the DOS version. Like Version 1.0, 

Version 2.0 of CAP88-PC was approved for demonstrating compliance with 40 CFR Part 61 in 

October 1999. 

In May 2002, CAP88-PC, Version 2.1 was issued. Version 2.1 included changes in installation 

and operating environment (e.g., improvements in the Windows code error handling), as well as 

changes to increase the programs flexibility (e.g., site-specific humidity, site-specific distance 

and sector, and higher radionuclide limit). 

In August 2002, CAP88-PC, Version 3.0 was issued. Version 3.0 is a significant update to 

Version 2.1. Some of the Version 3 enhancements include: 

• Incorporated the dose and risk factors from Federal Guidance Report (FGR) 13, in place 

of the RADRISK data that was used in previous versions 

• Expansion of the nuclide database to 825 nuclides which include all the FGR 13-based 

decay chains 

• Eliminated calculation of genetic effects 

• Dose factors are now a function of chemical form where specified in FGR 13 
WA 1-04, Task 3 4 SC&A – August 31, 2010

• Organ dose equivalent is calculated for 23 internal organs, mortality risk is calculated for 

15 cancer sites 

• Internal absorption class terminology updated to F (fast), M (medium), and S (slow) 

• All particulates are assumed to be 1.0 micron in accordance with the FGR 13 model, with 

the exception of gases and vapor which are ‘0’ 

• Radionuclide transfer factors have been updated to reflect NCRP Report #123 

• Version 3 has added (though not fully implemented) age dependent dose factors, cancer 

morbidity risk factors, additional pathways such as drinking water ingestion and external 

exposure from multiple depths of soil 

In 1994 Maheras, et al. performed a benchmarking of CAP88 to the GENII computer program. 

The following is a summary of their results: 

The results of the benchmark tests were within the 95% acceptance region specified in 

the test protocol. CAP-88 was found to over-predict effective dose equivalent relative to 

GENII for elevated releases, largely because CAP-88 calculates a larger atmospheric 

dispersion factor (chi/Q) than does GENII using the same meteorological data. However, 

CAP-88 consistently under-predicted effective dose equivalent relative to GENII for 

ground-level releases. This was because CAP-88 accounts for the processes of plume 

depletion by dry and wet deposition while GENII does not account for these processes. 

The effect of depletion was tested and found to be most important for a ground-level 

release of a highly depositing species such as radioiodine which implies that acceptable 

benchmark results would be difficult to obtain for a highly depositing species. 

ANL/ES-161 presents the results from benchmarking CAP88 against MILDOS-AREA. The 

ANL/ES-161 results are summarized below in the MILDOS-AREA discussion (Section 2.5). 

CAP88-PC was benchmarked against RESRAD-OFFSITE and the results are presented in 

ANL/EVS/TM/06-3, Section 3. Four areas were tested: 

• Simple dispersion model – For the simple dispersion model, ANL/EVS/TM/06-3 

reported that the agreement between CAP88-PC and RESRAD-OFFSITE was good, and 

that the differences for all distances were approximately 6% or less, except at 100 meters 

where a 13% difference was found. ANL/EVS/TM/06-3 concluded that these differences 

can be attributed to variations in the vertical dispersion coefficient and the actual area 

source methodology. 

• Dry deposition – For dry deposition, good agreement between the codes was obtained for 

receptor distances of less than 10,000 meters. After 10,000 meters, the RESRADOFFSITE air concentration is about 3 times larger than that from CAP88-PC. 

• Wet deposition – Aside from the 100-meter location, RESRAD-OFFSITE and 

CAP88-PC results remain within 10% of each other out to a distance of approximately 

3,000 meters. Thereafter, the CAP88-PC results become increasingly larger than the 

RESRAD-OFFSITE results up to 80,000 meters. 
WA 1-04, Task 3 5 SC&A – August 31, 2010

• Plume rise – The RESRAD-OFFSITE and CAP88-PC plume rise results agree to within 

about 15% or less for receptor distances of less than 500 meters. After 500 meters, plume 

rise has negligible differences between the two programs. 

In DOE/ORO-2033, MEPAS was benchmarked against RESRAD-OFFSITE. Because CAP88 is 

linked to RESRAD to perform atmospheric dispersion calculations, DOE/ORO-2033 was in 

effect a benchmarking of CAP88 against MEPAS. Two comparisons were performed: 

• Air concentration – A constant emission of thorium-228 was assumed. The air 

concentration comparisons show that nearly identical results are obtained with the models 

for the direct air release scenario. 

• Deposition – The soil concentrations at 1 km resulting from deposition from the thorium228 plume over the 10 years. The deposition comparisons show the models give 

approximately the same results. At the 1.0-km distance, the magnitude of the predicted 

deposition rates reflects mainly the predicted air concentrations and the deposition 

velocities. 

Finally, Lehto, et al. (2000) state that the milk cow and meat cattle densities are entered into 

CAP88 in units of “per square kilometer, but this is erroneous according to [B. Parks].” If 

CAP88 is to be used, then the correct units for entering milk cow and meat cattle densities will 

need to be used. 

2.3 GENII with FRAMES 

The Hanford Environmental Dosimetry Upgrade Project was undertaken to incorporate the 

internal dosimetry models recommended by the International Commission on Radiological 

Protection (ICRP) into updated versions of the environmental pathway analysis models used at 

Hanford. The resulting second generation of Hanford environmental dosimetry computer codes 

was compiled in the Hanford Environmental Dosimetry System (Generation II, or GENII). The 

purpose of this coupled system of computer codes was to analyze environmental contamination 

resulting from acute or chronic releases to, or initial contamination of, air, water, or soil. This 

was accomplished by calculating radiation doses to individuals or populations. The GENII 

system was designed to provide a state-of-the-art, technically peer-reviewed, documented set of 

programs for calculating radiation doses from radionuclides released to the environment. 

GENII was designed to include the capabilities: 1) for calculating radiation doses for acute 

releases, with options for annual dose, committed dose, and accumulated dose; 2) for calculating 

the same types of doses from chronic releases; and 3) for evaluating exposure pathways 

including direct exposure via water (swimming, boating, and fishing), soil (surface and buried 

sources), air (semi-infinite cloud and finite cloud geometries), inhalation pathways, and ingestion 

pathways. 

The GENII release scenarios include acute releases to air from ground level or elevated sources, 

or to water; chronic releases to air from ground level or elevated sources, or to water; and initial 

contamination of soil or surfaces. GENII accounts for source term variations, including decay of 

radionuclides to the start of the exposure scenario, input of total radioactivity or specified 
WA 1-04, Task 3 6 SC&A – August 31, 2010

fractions, and input of measured concentrations in specified environmental media. Air transport 

options include both puff and plume models. Building wake effects can be included in acute 

atmospheric release scenarios. Interfaces were provided for external calculations of atmospheric 

dispersion, geohydrology, biotic transport, and surface water transport. The model used by 

GENII to estimate radionuclide concentration in edible plant portions considers uptake from two 

pathways: direct deposition and absorption through roots from soil. The model is a variant of 

that prepared for the NRC for use in Regulatory Guide 1.109. Target populations were identified 

by distance and direction for individuals, populations, and for intruders into contained sources. 

The code provides risk estimates for health effects to individuals or populations; these can be 

obtained using the code by applying appropriate risk factors to the effective dose equivalent or 

organ dose. In addition, GENII, Version 2 implements these models plus those of ICRP 

Publications 56 through 72 and the related risk factors published in Federal Guidance Report 13. 

The original version of GENII, released in 1988, was composed of seven interrelated computer 

codes and their associated data libraries. The connection between the codes is through data 

transfer files, i.e., the output of one code is stored in a file that can be read by the next code in the 

system. The environmental transport calculations were performed in ENV, while the individual 

and population doses were calculate in DOSE. The code DITTY was used to calculate long-term 

(>10,000 years) exposures. External and internal dose factors were calculated by the EXTDF 

and INTDF codes. Finally, two data preparation codes were provided: APPRENTICE and 

ENVIN. The experienced GENII user could stop the process at any point and edit the 

intermediate data transfer files to obtain specific information on the processes occurring or on 

intermediate results. 

For maximum flexibility, the most current version of GENII, Version 2.10, has been divided into 

several interrelated, but separate, exposure and dose calculations consisting of four independent 

atmospheric models, one surface water model, three independent environmental accumulation 

models, one exposure module, and one dose/risk module, each with a specific user interface. 

GENII, Version 2.10 operates within the Framework for Risk Analysis in Multimedia 

Environmental System (FRAMES). FRAMES allows the addition of other computer modules to 

the GENII system. For example, GENII does not explicitly include modules for performing 

groundwater transport calculations, however, with FRAMES, groundwater transport models can 

be incorporated into the GENII model. Additional information on FRAMES is provided in 

Section 2.3.1. 

In 1994, Maheras, et al. performed a benchmarking of CAP88 to the GENII computer program. 

The results of this benchmark are presented above in Section 2.2. 

ANL/EAD/TM-24 benchmarked GENII against RESRAD. Unfortunately, the 

ANL/EAD/TM-24 benchmarking was mostly interested in comparing the two codes’ ability to 

analyze ground contamination scenarios, rather than air release scenarios, so the 

ANL/EAD/TM-24 results are of little value to this Work Assignment. 
WA 1-04, Task 3 7 SC&A – August 31, 2010

2.3.1 FRAMES 

Over the past 35 years, medium specific models have been and will continue to be developed in 

an effort to understand and predict environmental phenomena, including fluid-flow patterns (e.g., 

groundwater, surface water, and air), contaminant migration and fate, human or wildlife 

exposures, impacts from specific toxicants to specific species and their organs, cost-benefit 

analyses, impacts from remediation alternatives, etc. The DOE Office of Environmental 

Management (DOE-EM), the EPA Office of Research and Development (EPA-ORD), and the 

EPA Office of Radiation and Indoor Air (EPA-ORIA) have realized the need for a common 

platform to access and link these medium-specific models. The objective is to 1) combine 

existing models and approaches that assess hazardous and radioactive releases in and their 

impacts on the environment into a single framework and 2) structure the framework into a 

flexible and versatile, user-friendly tool that meets the needs of both organizations. FRAMES 

has been developed by Pacific Northwest National Laboratory (PNNL) to meet this need. 

FRAMES is a software platform for selecting and implementing environmental software models 

for risk assessment and management problems. Currently, MEPAS and GENII are available in 

FRAMES, while other codes are scheduled to be included in the future. The FRAMES User 

Interface (FUI) allows users to link, select, and interact with environmental codes for 

environmental and human health analyses. The FUI is used to: create, access, save, and exit 

Global Input Data (GID) files; select module types and connections; run the scenario models in 

sequence; and perform several other functions. In this manner, FRAMES can be used to select 

the most desirable features of specific models and link them together into a superior single 

integrated model. For example, the output from a source term generation code (e.g., GALE) 

could be linked with a sophisticated atmospheric transport code (e.g., AERMOD) which is linked 

to an exposure pathways evaluation model (e.g., CAP88). 

Unfortunately, as stated above, at this time only MEPAS and GENII are available in FRAMES, 

and since these two programs perform similar calculations, it’s not clear that there is any 

advantage to the current FRAMES. Also, in order to take advantage of future FRAMES 

capabilities, the process necessary to setup and run a single model (i.e., GENII or MEPAS) 

within FRAMES is more complicated than to setup and run the same model outside of FRAMES 

(at least to the authors of this report). For these reasons, a wait-and-see attitude has been taken 

with regard to FRAMES, which will also influence the selection of GENII and MEPAS for use 

in this Work Assignment, since they are only available within FRAMES. 

2.4 RESRAD-OFFSITE 

RESRAD is a computer model developed by Argonne National Laboratory to estimate radiation 

doses and risks from RESidual RADioactive materials. Since its first release in 1989, RESRAD 

has been used widely by DOE, its operations and area offices, and its contractors for deriving 

limits for radionuclides in soil. RESRAD has also been used by the EPA, U.S. Army Corps of 

Engineers, NRC, industrial firms, universities, and foreign government agencies and institutions. 

RESRAD evaluates the radiological dose and excess cancer risk to an individual who is exposed 

while residing and/or working in an area where the soil is contaminated with radionuclides. 
WA 1-04, Task 3 8 SC&A – August 31, 2010

RESRAD-OFFSITE code is an extension of the original RESRAD code. The most current 

version is RESRAD-OFFSITE Version 2.6, which was released July 7, 2010. 

RESRAD-OFFSITE considers initial radiological contamination in soil in settings ranging from 

a clean cover layer on top of it to up to five partially saturated layers below it. The code has a 

capability to model the radiation exposure of an individual who spends time directly above the 

primary contamination (onsite) and in the vicinity of the primary contamination (offsite). 

Nine exposure pathways are considered in RESRAD-OFFSITE: direct exposure from 

contamination in soil, inhalation of particulates and radon, ingestion of plant foods, ingestion of 

meat, ingestion of milk, ingestion of aquatic foods, ingestion of water, and incidental ingestion of 

soil. By selecting different pathways, RESRAD-OFFSITE can be used to simulate various 

exposure scenarios, including Rural Resident Farmer, Urban Resident, Worker, and 

Recreationist. 

The RESRAD Users Manual and the RESRAD-OFFSITE website (http://web.ead.anl.gov/

resrad/home2/offsite.cfm) state that RESRAD-OFFSITE “links with the CAP88 computer code 

for performing air dispersion calculations”. 

Regarding radon, the RESRAD-OFFSITE Users Manual indicates that it uses the same model as 

RESRAD for onsite exposures, and the RESRAD Users Manual describes the radon model as: 

The primary environmental parameters that can influence the dispersion of radon in 

outdoor air are meteorological conditions, such as wind speed and stability class. The 

calculation of outdoor radon concentrations by using all these parameters requires a 

comprehensive atmospheric dispersion code such as the MILDOS-AREA code (...). 

These extensive computations are not practical for the purposes of the RESRAD code, 

because the average radon concentration outdoors on top of a radium-contaminated area 

would be dependent on the size of the contaminated area and the average wind speed, and 

it would not be very sensitive to other meteorological parameters. 

In addition, RESRAD-OFFSITE includes radon transport to an offsite location. Radon offsite 

“concentrations are computed [by RESRAD-OFFSITE] from the flux of radon released from the 

primary contamination and the in-growth and decay-adjusted Chi/Q factors for radon and its 

short-lived progeny, computed from the atmospheric transport model.” It is not clear from this if 

RESRAD-OFFSITE uses the CAP88 equilibrium fraction method for estimating the short-lived 

radon progeny concentrations (see Section 2.5), or if the progeny concentrations are calculated 

directly from the Bateman equation. 

RESRAD-OFFSITE was benchmarked against CAP88-PC and the results are presented in 

ANL/EVS/TM/06-3, Section 3, and summarized above in Section 2.2. 

ANL/EAD/TM-24 benchmarked RESRAD against GENII. Unfortunately, the 

ANL/EAD/TM-24 benchmarking was mostly interested in comparing the two codes’ ability to 

analyze ground contamination scenarios, rather than air release scenarios, so the 

ANL/EAD/TM-24 results are of little value to this Work Assignment. 
WA 1-04, Task 3 9 SC&A – August 31, 2010

In 2008, as part of their verification of MILDOS-AREA, Argonne National Laboratory (ANL) 

compared the MILDOS-AREA air dispersion component with that of the RESRAD-OFFSITE 

code. The results of that comparison are summarized below in Section 2.5. 

In DOE/ORO-2033, RESRAD-OFFSITE was benchmarked against MEPAS. Because CAP88 is 

linked to RESRAD to perform atmospheric dispersion calculations, DOE/ORO-2033 was, in 

effect, a benchmarking of CAP88 against MEPAS. The DOE/ORO-2033 results are summarized 

above in Section 2.2. 

2.5 MILDOS-AREA 

MILDOS estimates impacts from radioactive emissions from uranium milling facilities. These 

impacts are presented as dose commitments to individuals and the regional population within an 

80-km radius of the facility. Only airborne releases of radioactive materials are considered: 

releases to surface water and to groundwater are not addressed in MILDOS, i.e., liquid exposure 

pathways are not treated by MILDOS. Exposure pathways of concern are assumed to be 

inhalation of airborne radioactive material, ingestion of vegetables, meat, and milk contaminated 

via deposition, and external exposure to radiation emitted by airborne activity and activity 

deposited on ground surfaces. MILDOS can be used to evaluate population doses for NEPA 

assessments, maximum individual doses for predictive 40 CFR 190 compliance evaluations, or 

maximum offsite air concentrations for predictive 10 CFR 20 compliance evaluations. 

In the mid-1970s, UDAD (Uranium Dispersion And Dosimetry) was developed by ANL for the 

NRC to provide comprehensive estimates of the potential radiation dose rate and dose to the 

standard man and the standard population in the vicinity of a uranium processing facility, such as 

a uranium mill or mine. UDAD was applied, initially in 1976, for the assessment of the 

radiological impact of the Bear Creek uranium mining and milling project and was later 

expanded for generic evaluation of uranium milling in the United States. UDAD is documented 

in NUREG/CR-0553. 

In 1981, MILDOS (NUREG/CR-2011) was developed by Pacific Northwest Laboratory (PNL) 

from UDAD. The models and assumptions on which the MILDOS program was based are 

described in the NRC Regulatory Guide 3.51 and NUREG/CR-0553. Models were included in 

MILDOS to consider both point sources (stacks, vents) and area sources (ore pads, tailing areas). 

Particulate release is limited to radionuclides of the uranium-238 decay series (i.e., U-238, 

Th-230, Ra-226, and Pb-210). Other radionuclides within the U-238 series are implicitly 

accounted for under the secular equilibrium assumption. Gaseous release was limited to 

consideration of Rn-222, plus ingrowth of daughters. The dose to exposed individuals is 

calculated for comparison with requirements of both 40 CFR 190 and 10 CFR Part 20. Ingestion 

dose factors were based on ICRP Publication 2 and 10A, inhalation dose factors were calculated 

in accordance with the ICRP’s Task Group on Lung Dynamics’ lung model (TGLM) (ICRP 

1966 and 1972), and external dose factors were directly taken from Hones and Soldat (1977). 

In 1989, Argonne National Laboratory developed the MILDOS-AREA code (ANL/ES-161) to 

provide enhanced capability to compute doses from large-area sources and to incorporate 

changes in methods for dosimetry calculations (ICRP 1979). The revised program was designed 
WA 1-04, Task 3 10 SC&A – August 31, 2010

for use on IBM or IBM-compatible personal computers. MILDOS-AREA considers the same 

radionuclides as MILDOS. A validation study of MILDOS-AREA was conducted using 

measured Rn-222 concentration and flux data from the Monticello, Utah uranium mill tailings 

impoundment. The results of this study demonstrated that use of MILDOS-AREA can result in 

generally good agreement between model-generated and measured Rn-222 concentrations. 

In 1997, MILDOS-AREA computer code was further updated by ANL to incorporate dose 

conversion factors derived by the ICRP recommendations of 1978, and to make it compatible 

with the January 1, 1994, revision of 10 CFR Part 20. The 1997 update also created an example 

problem for applying MILDOS-AREA to in-situ leach facilities. 

In 1998, MILDOS-AREA was provided with the user-friendly software interface. This graphical 

user interface (GUI) is simple and easy to use and allows MILDOS-AREA to run under the 

Windows operating system. 

ANL/ES-161, Appendix B presents a comparison between MILDOS-AREA and CAP881

. 

Calculated Rn-222 concentrations and working levels calculated by the two codes at 12 distances 

and four directions were compared. The Rn-222 concentrations calculated by the two codes are 

in very good agreement for distances greater than about 1 km for the release point, and, at closer 

distances, the CAP88 calculated Rn-222 concentrations are as much as 50% higher than the 

MILDOS-AREA concentrations. 

However, for the working level calculations, the results are much different. Near the source 

(e.g., <1 km), the CAP88 calculated working levels are much greater (sometimes greater than an 

order of magnitude) than the MILDOS-AREA calculated working levels. At larger distances 

(e.g., 5 to 10 km), the working levels calculated by the two codes are about the same, and at even 

larger distances (e.g., 70 km), the MILDOS-AREA calculated working levels are greater (by up 

to about 50%) than the CAP88 calculated working levels. The reason for this is the different 

approaches used by the two codes to calculate radon decay product concentrations. CAP88 uses 

a fixed linear interpolation of the decay product equilibrium fraction beginning at 0.267 at 150 

meters and reaching a final equilibrium fraction of 0.698 at 19,551 meters. MILDOS-AREA, on 

the other hand, directly calculates the radon daughter concentrations based on the Rn-222 

concentration and plume travel time. The ANL/ES-161, Appendix B results indicate that radon 

daughter equilibrium factors are significantly less than 27% at small distances and greater than 

70% at very large distances from the source. 

In 2008, ANL prepared a limited-scope verification and benchmarking of MILDOS-AREA by 

comparing spreadsheet calculation results with MILDOS-AREA-generated reports. The 

differences between the simple spreadsheet calculations and the MILDOS-AREA-generated 

reports were less than 5%, and in most cases the results were within 3%. The MILDOS-AREA 

air dispersion component was also compared with that of the RESRAD-OFFSITE code. The 

major differences between the two codes that were identified by ANL are presented below: 

 

1

 ANL/ES-161 actually compared MILDOS-AREA to AIRDOS-EPA. However, since CAP88 uses the same 

methodology for calculating Rn-222 air concentrations and working levels as AIRDOS-EPA, the results of the 

ANL/ES-161 comparison are valid for CAP88. 
WA 1-04, Task 3 11 SC&A – August 31, 2010

● Dose Outputs: Population doses and organ doses are not included in the 

RESRAD-OFFSITE code. 

● Different Default Values: 

- The codes use different default dose conversion factors and consumption 

rates. 

- MILDOS-AREA assumes U-234 is in equilibrium with U-238. 

● Differences in Release, Dispersion, and Deposition Models: 

- In RESRAD-OFFSITE, both dry deposition and wet deposition are 

considered, whereas only dry deposition is considered in MILDOS-AREA. 

- RESRAD-OFFSITE uses the average mass loading, deposition velocity, 

average concentration, and source area to calculate the source term (release 

rate), whereas MILDOS-AREA uses windblown particle emission to calculate 

the source term. 

- The RESRAD-OFFSITE code does not include resuspension from ground 

surface deposition in air concentration calculations. 

- In RESRAD-OFFSITE, accumulation in offsite surface soil includes 

accumulation due both to irrigation with contaminated water and to deposition 

of contaminated dust, whereas only deposition of contaminated dust is 

included in MILDOS-AREA. 

- In RESRAD-OFFSITE, the soil concentration is affected by mixing in the 

surface layer, erosion, and leaching, whereas in MILDOS-AREA, it is 

affected by the constant deposition and environmental loss. 

- RESRAD-OFFSITE calculates the average air and soil concentrations from 

deposition for different selected areas, whereas MILDOS-AREA calculates air 

concentration and ground deposition at a specified receptor location (no area 

associated). 

● Differences in Exposure Pathways: 

- The RESRAD-OFFSITE code does not include air submersion pathway dose. 

- External pathway dose in MILDOS-AREA is calculated by assuming infinite 

surface source, whereas RESRAD-OFFSITE calculates it by assuming a finite 

volume source with uniform concentration within the mixing layer. 

- In calculating radionuclide concentration in the edible part of the plant, 

RESRAD-OFFSITE includes root uptake from contaminated soil, foliar 

uptake from overhead irrigation, and foliar uptake of dust; MILDOS-AREA 

does not include uptake from irrigation. 

- There are five categories of plants in MILDOS-AREA: edible above-ground 

vegetables, potatoes, other edible below-ground vegetables, pasture grass, and 
WA 1-04, Task 3 12 SC&A – August 31, 2010

hay. The edible above-ground vegetables, potatoes, and below-ground 

vegetables are for human consumption, and pasture grass and hay are for 

animal consumption. There are four categories of plants in RESRADOFFSITE: fruit, grain, nonleafy vegetables; leafy vegetables; pasture and 

silage; and hay. The fruit, grain, nonleafy vegetables and leafy vegetables are 

for human consumption, and pasture, silage and hay are for animal 

consumption. 

- In RESRAD-OFFSITE, it is assumed that ingestion of contaminated plants, 

soil, and water all contribute to meat and milk contamination. In MILDOSAREA, contaminated soil and water ingestion is not included. 

2.6 MEPAS with FRAMES 

The Mu1timedia Environmental Pollutant Assessment System (MEPAS) is an integrated 

software implementation of physics-based fate and transport models for health and 

environmental risk assessments of both radioactive and hazardous pollutants. MEPAS is a 

“multimedia” model in that pollutant transport is modeled within, through, and between multiple 

media (air, soil, groundwater, and surface water). The estimated concentrations in the various 

media are used to compute exposures and impacts to the environment, to maximum individuals, 

and to populations. Of most import to this Work Assignment, the MEPAS atmospheric 

component for the air media includes models for emission from a source to the air, initial plume 

rise and dispersion, airborne pollutant transport and dispersion, and deposition to soils and crops. 

MEPAS, developed by PNL, is a suite of integrated impact assessment software comprising 

physics-based fate and environmental transport models of air, soil, and water media. MEPAS 

simulates the release of contaminants from a source; transport through the air, groundwater, 

surface water, and/or overland pathways; and transfer through food chains and exposure 

pathways to the exposed individual or population. For human health impacts, risks are computed 

for carcinogens and hazard quotients for noncarcinogens. 

In DOE/ORO-2033, MEPAS was benchmarked against RESRAD-OFFSITE. Because CAP88 is 

linked to RESRAD to perform atmospheric dispersion calculations, DOE/ORO-2033 was, in 

effect, a benchmarking of CAP88 against MEPAS. The DOE/ORO-2033 results are summarized 

above in Section 2.2. 

The most current version of MEPAS operates within FRAMES. FRAMES allows the addition 

of other computer modules to MEPAS. Additional information on FRAMES is provided in 

Section 2.3.1. 

2.7 AERMOD 

The American Meteorological Society/Environmental Protection Agency Regulatory Model 

Improvement Committee (AERMIC) was formed to introduce state-of-the-art modeling concepts 

into the EPA’s air quality models. Through AERMIC, a modeling system, AERMOD, was 

developed as a state-of-the-practice Gaussian plume dispersion model whose formulation is 

based on planetary boundary layer principles. The AERMOD model utilizes a probability 
WA 1-04, Task 3 13 SC&A – August 31, 2010

density function and the superposition of several Gaussian plumes to characterize the distinctly 

non-Gaussian nature of the vertical pollutant distribution for elevated plumes during convective 

conditions; otherwise the distribution is Gaussian. Also, nighttime urban boundary layers (and 

plumes within them) have the turbulence enhanced by AERMOD to simulate the influence of the 

urban heat island. The AERMOD model is applicable to rural and urban areas, flat and complex 

terrain, surface and elevated releases, and multiple sources (including point, area and volume 

sources). 

The development of AERMOD began in 1991 and underwent seven steps: initial model 

formulation, developmental evaluation, internal peer review/beta testing, revised model 

formulation, performance evaluation and sensitivity testing, external peer review, and 

submission to the EPA for consideration as a regulatory model. On November 9, 2005, EPA 

issued the final rule to replace the widely used Industrial Source Complex (ISC) air dispersion 

model with the state-of-practice air dispersion model AERMOD in many air quality impact 

assessments. 

Because AERMOD only calculates atmospheric dispersion and deposition, but not dose to 

individual and the population through the exposure pathways, it would be necessary to link 

AERMOD to either an existing or custom designed and developed program in order to evaluate 

dose and risk. Although it may be a worthwhile effort to upgrade the atmospheric dispersion 

capabilities of a dose evaluation program (such as CAP88) to include the AERMOD dispersion 

models, it is beyond the scope of this Work Assignment, and AERMOD will not be evaluated 

further. 

2.8 GASPAR-II 

The GASPAR code was written in 1977 by Oak Ridge National Laboratory for the NRC. 

GASPAR is an air release dose code that models the release of noble gases in a semi-infinite 

plume, radioiodine and particulate emissions using the release model described in NRC 

Regulatory Guide 1.109 (NRC 1977). The code was developed mainly to analyze effluent 

releases from nuclear power operations. GASPAR considers such pathways as inhalation, 

plume-immersion, ground-shine, and ingestion of various contaminated media (meat, milk, 

vegetation, etc.). Dose calculations can be applied to a defined population or an individual who 

are evaluated for four age groups: infants (0-1 years), children (1-11 years), teens (12-18 years), 

and adults (over 18 years). Each calculation considers seven organs (bone, G.I. tract, kidney, 

liver, lung, skin, and thyroid) as well as the whole body dose. 

In 1987, GASPAR-II was developed by PNL, however, while changes were made to the values 

of some parameters and dose factors used in the code, no changes were made to the 

mathematical models used by GASPAR. 

GASPAR was eliminated from further consideration in this Work Assignment for the following 

reasons: 

• Dose factors – GASPAR-II utilizes the inhalation and ingestion dose factors from ICRP 

Publication 2, as modified slightly in later ICRP documents. Since ICRP Publication 2 
WA 1-04, Task 3 14 SC&A – August 31, 2010

was published in 1959, the ICRP has issued two major updates of its dosimetric guidance. 

The details of these ICRP updates have been provided in SC&A 2009. Thus, the 

dosimetry used by GASPAR-II is out-of-date and cannot be readily updated. 

• Atmospheric dispersion – GASPAR-II does not calculate atmospheric dispersion, 

therefore it would be necessary to utilize a separate program (such as XOQDOQ) to 

process the raw meteorological data and generate atmospheric dispersion and deposition 

factors for input into GASPAR-II. 

• Risk factors – GASPAR-II only calculates radiological dose, and does not calculate risk. 

Although it is possible to convert the doses reported by GASPAR-II into risk by 

designing and using a post-processor, it is believed that such an approach would not be 

practicable for various reasons, including the fact that the GASPAR-II doses are based on 

ICRP Publication 2. 

2.9 GENII-NESHAPS 

GENII-NESHAPS is a modified version of the more general GENII code which was designed to 

help site managers plan and improve compliance with 40 CFR 61, Subparts H and I. The code 

implements the same methods as the original GENII code, except it hardwires certain parameters 

so that they cannot be changed by the user. This was done so that the code would automatically 

incorporate certain elements necessary to the NESHAPS regulation. 

The following statement is currently being displayed on the EPA website (http://www.epa.gov/

rpdweb00/neshaps/models.html): 

EPA does not presently support GENII-NESHAPs, and there is no intention to do so. 

Because of this and the fact that GENII is being evaluated for use, GENII-NESHAPS was 

eliminated from further consideration in this Work Assignment. 
WA 1-04, Task 3 15 SC&A – August 31, 2010

3.0 DETAILED MODEL EVALUATIONS 

3.1 Evaluation Criteria 

The evaluation criteria used were: 

● Exposure Pathways Modeled (2): Are all of the exposure pathways that are essential to 

this analysis included in the code? Additionally, does the code allow for exposures to 

different age groups (i.e., adults, teens, children, infants) and/or sexes to be calculated? 

● Population Based Dose/Risk Capability (2): Does the code allow for the calculation of 

a population dose/risk based on a site-specific unique population distribution or does the 

code only allow the calculation of dose/risk based on a single defined receptor location? 

● Dose Factors Used (1.75): Does the code utilize dose conversion factors based on the 

most recent International Commission on Radiological Protection (ICRP) 

recommendations? 

● Risk Factors Used (1.75): Does the code utilize the most recent risk factors? 

● Processing of Meteorological Data (1.5): Can the code process “raw” meteorological 

data, or does the meteorological data need to be pre-processed prior to being entered into 

the code? For example, does the code accept “raw” meteorological tower data (e.g., from 

http://www.epa.gov/scram001/surfacemetdata.htm), or does it accept joint frequency 

data, or does it only accept dispersion and deposition factors? If a code does not include 

the capability to process “raw” meteorological data, than a separate code (e.g., STAR 

from http://www.epa.gov/scram001/metobsdata_procaccprogs.htm) would need to be run 

to generate the input necessary for the risk assessment model. 

● Source Term Calculation (1.5): Can the code calculate radon releases, or must the 

releases be pre-calculated and entered into the code? If a code does not include the 

capability to calculate the radon release, than an additional calculation would be needed 

to estimate the source term so that it can be entered into the risk assessment model. 

Alternatively, a code that contains an internal source term calculation would be difficult 

to modify should the source term model change. 

● Verification and Validation (1.25): Is there a readily available V&V package that 

supports the code? Is the V&V package complete? Has there been independent (i.e., by 

someone other than the code’s developer) V&V performed? 

● Ease of Use/User Friendly (1.25): Is the code provided with a user interface that is 

intuitive and easy to understand and use? Alternatively, does the code require the user to 

manipulate structured input data files? Additionally, does the code have features not 

required for this analysis, but that might complicate its use? 

● Documentation (1): Is the code well documented? Are there User’s Manuals readily 

available? In addition to providing instructions as to how to use the code, are the 

mathematical models used by the code well documented? It is expected that all of the 

codes selected for evaluation would have high scores for this criteria. 
WA 1-04, Task 3 16 SC&A – August 31, 2010

● Input Parameter Sensitivity Analysis (1): Does the code have the capability to perform 

sensitivity analyses on the input data, or must parameter sensitivity be determined by 

multiple runs, each run varying a single parameter? EPA 1989, Section 7 describes 

uncertainty analyses that were performed. Although this Work Assignment does not 

specify them, EPA may want to perform similar uncertainty analyses for this revision in 

the future. 

● Probabilistic Analysis Capability (1): Is there a probabilistic analysis version of the

code available? Although the calculations being performed for WA 1-04 are being done 

deterministically, at some point the EPA may desire to perform a probabilistic analysis, 

and it would be desirable to use the same code for both analyses. 

● SC&A Familiarity (tie breaker): If two or more models have identical (or nearly 

identical [i.e., within 10%]) scores based on the above criteria, then the SC&A 

recommendation will be based on how familiar SC&A is with the operation of each code. 

The above list of evaluation criteria is preliminary, and SC&A will work with the Work 

Assignment Manager (WAM) to finalize the code evaluation criteria. As can be seen from the 

above list, some criteria are of greater importance that other criteria. To account for this, each 

criterion will be given a weighting factor ranging from 1 to 2; preliminary weighting factors are 

shown in parenthesis on the above list of evaluation criteria. SC&A will work with the WAM to 

develop the final weighting factors for each criterion. The final score of the evaluation will be 

the sum of each criterion’s score times its weighting factor. 

Table 1. Evaluation Criteria 

Evaluation Criteria Weight 

Factor 

Exposure Pathways Modeled 2 

Population Dose/Risk Capability 2 

Dose Factors Used 1.75 

Risk Factors Used 1.75 

Meteorological Data Processing 1.5 

Source Term Calculations 1.5 

Verification and Validation 1.25 

Ease of Use/User Friendly 1.25 

Documentation 1 

Sensitivity Analysis Capability 1 

Probabilistic Analysis Capability 1 

SC&A Familiarity N/A 

3.2 CAP88 

3.2.1 Exposure Pathways Modeled (2) 

Criteria: Are all of the exposure pathways that are essential to this analysis included in the 

code? Additionally, does the code allow for exposures to different age groups (i.e., adults, teens, 

children, infants) and/or sexes to be calculated? 
WA 1-04, Task 3 17 SC&A – August 31, 2010

Evaluation: CAP88 calculated dose and risk from exposure pathways including ingestion, 

inhalation, ground-level immersion (external), and ground-surface irradiation (external). 

In cases considering Rn-222 decay products, CAP88 calculates the working levels associated 

with the contaminants and evaluates the risk, but not dose, from the working level calculations. 

Code documentation states that current version ‘contains (not implemented) data for – age 

dependent dose factors’. It does not appear that this is a selectable option, nor does it appear to 

report age-specific analyses in the output files. No mention of gender-specific analyses in the 

associated documentation. Previous versions of the code implemented a ‘genetic effects’ 

calculation which has been removed. 

Score: 5 Weighted Score: 10 

3.2.2 Dose Factors Used (1.75) 

Criteria: Does the code utilize dose conversion factors based on the most recent International 

Commission on Radiological Protection (ICRP) recommendations? 

Evaluation: “CAP-88 uses a database of dose and risk factors provided in Federal Guidance 

Report 13. Dose and risk conversion factors include the effective dose equivalent calculated 

according to the methods of ICRP Publication Number 72 (ICRP 72).” – User Guide 12/9/07. 

ICRP-72 are the most recent dose conversion factors used in the codes under evaluation. 

Score: 5 Weighted Score: 8.75 

3.2.3 Risk Factors Used (1.75) 

Criteria: Does the code utilize the most recent risk factors? 

Evaluation: “CAP-88 uses a database of dose and risk factors provided in Federal Guidance 

Report 13. Dose and risk conversion factors include the effective dose equivalent calculated 

according to the methods of ICRP Publication Number 72 (ICRP 72).” – User Guide 12/9/07 

Score: 5 Weighted Score: 8.75 

3.2.4 Population Based Dose/Risk Capability (2): 

Criteria: Does the code allow for the calculation of a population dose/risk based on a sitespecific unique population distribution or does the code only allow the calculation of dose/risk 

based on a single defined receptor location? 
WA 1-04, Task 3 18 SC&A – August 31, 2010

Evaluation: CAP88 allows for the calculation of dose/risk based on both a maximally exposed 

individual (user defined) or additionally to load population data in the form of a ‘.POP’ file. The 

CAP88 software package contains 28 preloaded population files. 

Score: 5 Weighted Score: 10 

3.2.5 Meteorological Data Processing (1.5) 

Criteria: Can the code process “raw” meteorological data, or does the meteorological data need 

to be pre-processed prior to being entered into the code? For example, does the code accept 

“raw” meteorological tower data, or does it accept joint frequency data, or does it only accept 

dispersion and deposition factors? 

Evaluation: ‘Wind Files’ (as created by the National Weather Service) are required to run 

CAP88. Site-specific meteorological data can be processed using an associated ‘Stability Array 

Distribution’ module to convert the on-site data to the correctly formatted ‘Wind File’. The 

module GETWIND allows for the conversion of STAR formatted meteorological data to the 

CAP88 formatted ‘wind file’. 

Meteorological data files from over 350 sites within the U.S. are provided as part of the CAP88 

code package. 

Score: 5 Weighted Score: 7.5 

3.2.6 Source Term Calculation (1.5) 

Criteria: Can the code calculate radon releases, or must the releases be pre-calculated and 

entered into the code? 

Evaluation: Radionuclide releases are entered manually in CAP88 in the form of Curie/yr. 

Score: 2 Weighted Score: 3 

3.2.7 Verification and Validation (1.25) 

Criteria: Is there a readily available V&V package that supports the code? Is the V&V package 

complete? Has there been independent (i.e., by someone other than the code’s developer) V&V 

performed? 

Evaluation: Main QA Documents: 

Maheras, S.J.; Ritter, P.D.; Leonard, P.R.; and Moore, R. Benchmarking of the CAP-88 and 

GENII Computer Codes Using 1990 and 1991 Monitored Atmospheric Releases from the Idaho 

National Engineering Laboratory, Health Physics 67:509-517; November 1994. 
WA 1-04, Task 3 19 SC&A – August 31, 2010

Fields, D.E.; Miller, C.W.; Cotter, S.J. Validation of the AIRDOS-EPA Computer Codes by 

Simulating Intermediate Range Transport of Kr-85 from the Savannah River Plant. Atmos. 

Environ. 18:2029-2036; 1984. 

Score: 5 Weighted Score: 6.25 

3.2.8 Ease of Use/User Friendly (1.25) 

Criteria: Is the code provided with a user interface that is intuitive and easy to understand and 

use? Alternatively, does the code require the user to manipulate structured input data files? 

Additionally, does the code have features not required for this analysis, but that might complicate 

its use? 

Evaluation: Code contains very intuitive menus which prompt the user in a linear fashion to 

enter all pertinent model data. Of the five main codes analyzed in detail, CAP88 is the easiest to 

implement and most user friendly. 

Score: 5 Weighted Score: 6.25 

3.2.9 Documentation (1) 

Criteria: Is the code well documented? Are there User’s Manuals readily available? In 

addition to providing instructions as to how to use the code, are the mathematical models used by 

the code well documented? 

Evaluation: The mathematical models and equations used by the code are presented in 

Chapter 12 of the user’s guide. 

“Mathematical Models in CAP88-PC” (Parks, DOE, 1997) provides additional documentation 

beyond the User’s Manual. 

Score: 5 Weighted Score: 5 

3.2.10 Sensitivity Analysis Capability (1) 

Criteria: Does the code have the capability to perform sensitivity analyses on the input data, or 

must parameter sensitivity be determined by multiple runs, each run varying a single parameter? 

Evaluation: Sensitivity analyses can only be carried out using individual runs. 

Score: 0 Weighted Score: 0 

3.2.11 Probabilistic Analysis Capability (1) 

Criteria: Is there a probabilistic analysis version of the code available? 
WA 1-04, Task 3 20 SC&A – August 31, 2010

Evaluation: Probabilistic analysis is not available for this code. 

Score: 0 Weighted Score: 0 

3.2.12 SC&A Familiarity (N/A) 

Criteria: To be used as a tiebreaker when the top two codes have a final score within 10% of 

each other. 

Evaluation: SC&A has very good overall familiarity with the CAP88 code, as SC&A helped 

assist EPA in the development of the mainframe version of the code, as well as assisted in 

writing the User’s Manual. Since that time, SC&A has continued to use CAP88 in our 

consulting work for various clients. 

3.3 GENII with FRAMES 

3.3.1 Exposure Pathways Modeled (2) 

Criteria: Are all of the exposure pathways that are essential to this analysis included in the 

code? Additionally, does the code allow for exposures to different age groups (i.e., adults, teens, 

children, infants) and/or sexes to be calculated? 

Evaluation: Exposure pathways include: external (air immersion, ground-shine, recreational 

swimming/boating/shoreline exposure), ingestion (food crops, animal products, aquatic food, 

inadvertent soil, drinking water), and inhalation (air, resuspended soil, inhalation of waterborne 

contaminants). 

Radon is considered a special radionuclide model for GENII along with tritium and carbon-14. 

Score: 5 Weighted Score: 10 

3.3.2 Dose Factors Used (1.75) 

Criteria: Does the code utilize dose conversion factors based on the most recent International 

Commission on Radiological Protection (ICRP) recommendations? 

Evaluation: “The GENII computer code was developed for the Environmental Protection 

Agency (EPA) at Pacific Northwest National Laboratory (PNNL) to incorporate the internal 

dosimetry models recommended by the International Commission on Radiological Protection 

(ICRP) and radiological risk estimating procedures of Federal Guidance Report 13 into updated 

versions of existing environmental pathway analysis models.”– GENII Users’ Guide, October 

2004 

ICRP documents are noted as publications 56-72. 

Score: 4 Weighted Score: 7 
WA 1-04, Task 3 21 SC&A – August 31, 2010

3.3.3 Risk Factors Used (1.75) 

Criteria: Does the code utilize the most recent risk factors? 

Evaluation: “The GENII computer code was developed for the Environmental Protection 

Agency (EPA) at Pacific Northwest National Laboratory (PNNL) to incorporate the internal 

dosimetry models recommended by the International Commission on Radiological Protection 

(ICRP) and radiological risk estimating procedures of Federal Guidance Report 13 into updated 

versions of existing environmental pathway analysis models.”– GENII Users’ Guide, October 

2004 

Score: 5 Weighted Score: 8.75 

3.3.4 Population Based Dose/Risk Capability (2): 

Criteria: Does the code allow for the calculation of a population dose/risk based on a sitespecific unique population distribution or does the code only allow the calculation of dose/risk 

based on a single defined receptor location? 

Evaluation: GENII within FRAMES can perform calculations for populations but must have 

population distributions that match the format of the meteorological data and must be 

constructed in ASCII format by the user. GENII does not have any preloaded population files 

available. 

Score: 3 Weighted Score: 6 

3.3.5 Meteorological Data Processing (1.5) 

Criteria: Can the code process “raw” meteorological data, or does the meteorological data need 

to be pre-processed prior to being entered into the code? For example, does the code accept 

“raw” meteorological tower data, or does it accept joint frequency data, or does it only accept 

dispersion and deposition factors? 

Evaluation: GENII uses its own specific format for meteorological data, but contains modules 

to convert some different data types such as: 

- two different types of JFD (Joint Frequency Data) data: EPA’s Industrial Source 

Complex model (ISC3 also known as STAR summary), and the format used by the 

original GENII (1988). 

- “Card Deck 144 format” (CD-144) and SAMSON data format: available from the 

National Climatic Data Center (NCDC). 

Score: 5 Weighted Score: 7.5 
WA 1-04, Task 3 22 SC&A – August 31, 2010

3.3.6 Source Term Calculation (1.5) 

Criteria: Can the code calculate radon releases, or must the releases be pre-calculated and 

entered into the code? 

Evaluation: All radionuclide releases, whether acute or chronic, must be entered into GENII by 

the user. GENII does not have any capability to calculate the airborne release of radon. 

Score: 2 Weighted Score: 3 

3.3.7 Verification and Validation (1.25) 

Criteria: Is there a readily available V&V package that supports the code? Is the V&V package 

complete? Has there been independent (i.e., by someone other than the code’s developer) V&V 

performed? 

Evaluation: “Both GENII versions were developed under QA plans based on the American 

National Standards Institute (ANSI) standard NQA-1 as implemented in the PNNL Quality 

Assurance Manual. All steps of the code development have been documented and tested, and 

hand calculations have verified the code’s implementation of major transport and exposure 

pathways for a subset of the radionuclide library. A collection of hand calculations and other 

verification activities is available... The code has been reviewed by the EPA Science Advisory 

Board and a separate EPA-sponsored, independent peer review panel. The QA of both GENII 

Version 1.485 and Version 2 have been reviewed by the US Department of Energy.” – GENII 

Users’ Guide, October 2004 

Score: 5 Weighted Score: 6.25 

3.3.8 Ease of Use/User Friendly (1.25) 

Criteria: Is the code provided with a user interface that is intuitive and easy to understand and 

use? Alternatively, does the code require the user to manipulate structured input data files? 

Additionally, does the code have features not required for this analysis, but that might complicate 

its use? 

Evaluation: GENII Version 2 functions within FRAMES which allows the code to run in 

conjunction with, and provide input to, other modeling codes (such as MEPAS). While this 

allows for more dynamic modeling efforts using GENII with other codes, the strict use of GENII 

is not as straightforward because of the complexity of integrating the different codes and 

executing the FRAMES system itself. 

Score: 1 Weighted Score: 1.25 
WA 1-04, Task 3 23 SC&A – August 31, 2010

3.3.9 Documentation (1) 

Criteria: Is the code well documented? Are there User’s Manuals readily available? In 

addition to providing instructions as to how to use the code, are the mathematical models used by 

the code well documented? 

Evaluation: User manuals and input guidance reports are readily available on the Internet from 

various reputable sources. Equations and methodology underlying the code is well documented 

in: 

Napier, B.A.; Strenge, D.L.; Ramsdell Jr., J.V.; Eslinger, P.W.; Fosmire, C. GENII Version 2 

Software Design Document. Prepared for U.S. Environmental Protection Agency. November 

2004. 

Score: 5 Weighted Score: 5 

3.3.10 Sensitivity Analysis Capability (1) 

Criteria: Does the code have the capability to perform sensitivity analyses on the input data, or 

must parameter sensitivity be determined by multiple runs, each run varying a single parameter? 

Evaluation: GENII does include a ‘Sensitivity and Uncertainty’ module as described in the 

following: “FRAMES is currently designed for deterministic environmental and human health 

impact models. The Sensitivity/Uncertainty Multimedia Modeling Module (SUM3) software 

product was designed to allow statistical analysis using the existing deterministic models 

available in FRAMES. SUM3 randomly samples input variables and preserves the associated 

output values in an external file available to the user for evaluation.” 

Score: 4 Weighted Score: 4 

3.3.11 Probabilistic Analysis Capability (1) 

Criteria: Is there a probabilistic analysis version of the code available? 

Evaluation: The GENII Sensitivity and Analysis module allows the user to specify probabilistic 

distributions to various deterministic parameters; this feature appears to be used only for 

determining which parameters contribute the most to the uncertainty of the output, but not 

necessarily allow the user to run a probabilistic simulation which produces a distribution of 

output values. 

Score: 4 Weighted Score: 4 

3.3.12 SC&A Familiarity (N/A) 

Criteria: To be used as a tiebreaker when the top two codes have a final score within 10% of 

each other. 
WA 1-04, Task 3 24 SC&A – August 31, 2010

Evaluation: SC&A has previously used GENII to support EPA’s evaluation of the technical and 

regulatory issues associated with the disposition of scrap metal from nuclear facilities, as well as 

to support EPA in the development of radiological exposure standards for the Yucca Mountain 

high-level waste disposal facility. However, although we have obtained and installed FRAMESbased GENII for this Work Assignment, to date, SC&A has not had the opportunity to use 

FRAMES-based GENII in any of our work. 

3.4 RESRAD-OFFSITE 

3.4.1 Exposure Pathways Modeled (2) 

Criteria: Are all of the exposure pathways that are essential to this analysis included in the 

code? Additionally, does the code allow for exposures to different age groups (i.e., adults, teens, 

children, infants) and/or sexes to be calculated? 

Evaluation: RESRAD is designated to evaluate ground contamination with residual 

radioactivity, not the airborne release pathways, although it does contain a radon model. It is 

important to note that RESRAD’s offsite air transport model utilizes the CAP88 methodology. 

Exposure pathways evaluated by RESRAD-OFFSITE include external gamma, inhalation, 

ingestion (plant, meat, milk, aquatic, inadvertent soil, drinking water), and radon. Internal dose 

conversion factors for ICRP-72 include factors by age (infant, 1, 5, 10, 15, and adult). No 

gender-specific analysis is available. 

Score: 5 Weighted Score: 10 

3.4.2 Dose Factors Used (1.75) 

Criteria: Does the code utilize dose conversion factors based on the most recent International 

Commission on Radiological Protection (ICRP) recommendations? 

Evaluation: Selectable between FGR 11 and ICRP-72 for internal exposures, FGR 12 and 

ICRP-60 for external exposures. 

Score: 5 Weighted Score: 8.75 

3.4.3 Risk Factors Used (1.75) 

Criteria: Does the code utilize the most recent risk factors? 

Evaluation: Risk factors are selectable between FGR 13 (morbidity/mortality) and Heast (2001) 

morbidity coefficients. 

Score: 5 Weighted Score: 8.75 
WA 1-04, Task 3 25 SC&A – August 31, 2010

3.4.4 Population Based Dose/Risk Capability (2): 

Criteria: Does the code allow for the calculation of a population dose/risk based on a sitespecific unique population distribution or does the code only allow the calculation of dose/risk 

based on a single defined receptor location? 

Evaluation: RESRAD can only calculate dose to an individual receptor as defined by the user. 

Population-based dose and risk calculations are not available with RESRAD- OFFSITE. 

Score: 0 Weighted Score: 0 

3.4.5 Meteorological Data Processing (1.5) 

Criteria: Can the code process “raw” meteorological data, or does the meteorological data need 

to be pre-processed prior to being entered into the code? For example, does the code accept 

“raw” meteorological tower data, or does it accept joint frequency data, or does it only accept 

dispersion and deposition factors? 

Evaluation: Joint frequency data can be input manually into the code or can also be read from a 

‘STAR’ file. A single stability class/wind speed can also be used in place of the joint frequency 

data. 

Meteorological data (in the STAR format) for 267 U.S. sites are provided with the code package. 

Score: 5 Weighted Score: 7.5 

3.4.6 Source Term Calculation (1.5) 

Criteria: Can the code calculate radon releases, or must the releases be pre-calculated and 

entered into the code? 

Evaluation: The code requires input of diffusion coefficients (from soil/cover, floor of a 

building, etc.) and other properties of radon, such as an emanation coefficient which will define 

the radon release value. 

Score: 4 Weighted Score: 6 

3.4.7 Verification and Validation (1.25) 

Criteria: Is there a readily available V&V package that supports the code? Is the V&V package 

complete? Has there been independent (i.e., by someone other than the code’s developer) V&V 

performed? 

Evaluation: The V&V package is contained in the document: 
WA 1-04, Task 3 26 SC&A – August 31, 2010

Yu, C.; Gnanapragasam, E.; Cheng, J.J.; Biwer, B. Benchmarking of RESRAD-OFFSITE: 

Transition from RESRAD (onsite) to RESRAD-OFFSITE and Comparison of the RESRADOFFSITE Predictions with Peer Codes. Environmental Science Division of Argonne National 

Laboratory. 

The document compares the code against CAP88 and ISCLT3 for atmospheric transport 

calculations and also against the base RESRAD code for onsite calculations, which itself was 

benchmarked against GENII-S, DECOM, PRESTO-EPA-CPG, and the NUREG/CR-5512 

methodology. 

Score: 5 Weighted Score: 6.25 

3.4.8 Ease of Use/User Friendly (1.25) 

Criteria: Is the code provided with a user interface that is intuitive and easy to understand and 

use? Alternatively, does the code require the user to manipulate structured input data files? 

Additionally, does the code have features not required for this analysis, but that might complicate 

its use? 

Evaluation: The code brings the user in a linear fashion through each of the input screens and 

provides a default value which will fit most situations. If the user tries to input a value that is 

outside the theoretical range for a given parameter, the code notifies the user and blocks them 

from entering the given value. 

Score: 4 Weighted Score: 2.5 

3.4.9 Documentation (1) 

Criteria: Is the code well documented? Are there User’s Manuals readily available? In 

addition to providing instructions as to how to use the code, are the mathematical models used by 

the code well documented? 

Evaluation: The main User Manual is available on the main code’s website which includes both 

a User’s Guide (Appendix A of the document) and the methods and equations used by the code 

(main body of the User Manual). 

Score: 5 Weighted Score: 5 

3.4.10 Sensitivity Analysis Capability (1) 

Criteria: Does the code have the capability to perform sensitivity analyses on the input data, or 

must parameter sensitivity be determined by multiple runs, each run varying a single parameter? 
WA 1-04, Task 3 27 SC&A – August 31, 2010

Evaluation: RESRAD-OFFSITE contains a sensitivity module that (unlike the basic RESRAD 

code) does not limit the number of parameters subjected to sensitivity in any given run. The 

sensitivity module can be run either by dividing/multiplying an input value by a discreet number. 

Score: 5 Weighted Score: 5 

3.4.11 Probabilistic Analysis Capability (1) 

Criteria: Is there a probabilistic analysis version of the code available? 

Evaluation: RESRAD-OFFSITE contains a probabilistic analysis feature that allows the user to 

specify a given distribution type (from 35 different choices: normal, lognormal, truncated 

lognormal, etc.) and specify the characteristics of the distribution. RESRAD-OFFSITE provides 

a default probabilistic distribution for each parameter which is documented in the RESRADOFFSITE user guide. 

Score: 4 Weighted Score: 4 

3.4.12 SC&A Familiarity (N/A) 

Criteria: To be used as a tiebreaker when the top two codes have a final score within 10% of 

each other. 

Evaluation: SC&A is very familiar with RESRAD and RESRAD-OFFSITE. We have run the 

code on numerous occasions, and in addition have used the RESRAD methodology as provided 

in the User’s Manual in our own analyses (e.g., the development of NUREG-1640). 

3.5 MILDOS-AREA 

3.5.1 Exposure Pathways Modeled (2) 

Criteria: Are all of the exposure pathways that are essential to this analysis included in the 

code? Additionally, does the code allow for exposures to different age groups (i.e., adults, teens, 

children, infants) and/or sexes to be calculated? 

Evaluation: MILDOS-AREA considers inhalation, external (groundshine and cloud 

immersion), and ingestion (vegetables, meat and milk). 

Score: 5 Weighted Score: 10 

3.5.2 Population Based Dose/Risk Capability (2): 

Criteria: Does the code allow for the calculation of a population dose/risk based on a sitespecific unique population distribution or does the code only allow the calculation of dose/risk 

based on a single defined receptor location? 
WA 1-04, Task 3 28 SC&A – August 31, 2010

Evaluation: MILDOS-AREA allows the user to load in a ‘.pop’ file similar to CAP88. 

MILDOS does not have any preloaded population distributions. Users can also create their own 

population files with properly formatted ASCII text documents. 

Score: 4 Weighted Score: 8 

3.5.3 Dose Factors Used (1.75) 

Criteria: Does the code utilize dose conversion factors based on the most recent International 

Commission on Radiological Protection (ICRP) recommendations? 

Evaluation: Dose conversion factors are based on ICRP 26 (1978) recommendations. 

Score: 2 Weighted Score: 3.5 

3.5.4 Risk Factors Used (1.75) 

Criteria: Does the code utilize the most recent risk factors? 

Evaluation: MILDOS-AREA appears to only calculate dose and not incorporate risk 

calculations into its output. 

Score: 0 Weighted Score: 0 

3.5.5 Meteorological Data Processing (1.5) 

Criteria: Can the code process “raw” meteorological data, or does the meteorological data need 

to be pre-processed prior to being entered into the code? For example, does the code accept 

“raw” meteorological tower data, or does it accept joint frequency data, or does it only accept 

dispersion and deposition factors? 

Evaluation: Joint frequency data can be input manually into the code or can also be read from a 

‘STAR’ file. Although meteorological data is not provided with MILDOS-AREA, the CAP88 

supplied meteorological data is in the STAR format and can be used with MILDOS-AREA. 

Alternatively, the RESRAD-OFFSITE supplied joint frequency data can be converted to the 

STAR format and used with MILDOS-AREA. 

Score: 4 Weighted Score: 6 

3.5.6 Source Term Calculation (1.5) 

Criteria: Can the code calculate radon releases, or must the releases be pre-calculated and 

entered into the code? 
WA 1-04, Task 3 29 SC&A – August 31, 2010

Evaluation: MILDOS-AREA is limited to only analyzing the U-238 decay series, specifically, 

U-238, Th-230, Ra-226, Pb-210, and Rn-222. MILDOS-AREA gives the user the option of 

entering the particulate release rates or of having the code calculate them. 

Score: 2 Weighted Score: 3 

3.5.7 Verification and Validation (1.25) 

Criteria: Is there a readily available V&V package that supports the code? Is the V&V package 

complete? Has there been independent (i.e., by someone other than the code’s developer) V&V 

performed? 

Evaluation: The document: ‘Verification and Benchmarking of the MILDOS-Area Code’ is 

available on the MILDOS-AREA website and contains internal quality assurance studies, 

benchmarking of the air release model against RESRAD-OFFSITE, and also verifications of 

modeled results against ‘spreadsheet calculations’ based on NUREG 1569 for a select ISL 

facility. 

Score: 5 Weighted Score: 6.25 

3.5.8 Ease of Use/User Friendly (1.25) 

Criteria: Is the code provided with a user interface that is intuitive and easy to understand and 

use? Alternatively, does the code require the user to manipulate structured input data files? 

Additionally, does the code have features not required for this analysis, but that might complicate 

its use? 

Evaluation: MILDOS-AREA is one of the most user-friendly of the main codes under 

assessment with simplistic data inputs that lead the user through each of the menus before 

running the code. 

Score: 5 Weighted Score: 6.25 

3.5.9 Documentation (1) 

Criteria: Is the code well documented? Are there User’s Manuals readily available? In 

addition to providing instructions as to how to use the code, are the mathematical models used by 

the code well documented? 

Evaluation: User’s Guide is readily available for the MILDOS-AREA code along with a User’s 

Manual which describes the underlying methods and equations used. Both can be found on the 

main website for MILDOS-AREA. 

Score: 5 Weighted Score: 5 
WA 1-04, Task 3 30 SC&A – August 31, 2010

3.5.10 Sensitivity Analysis Capability (1.5) 

Criteria: Does the code have the capability to perform sensitivity analyses on the input data, or 

must parameter sensitivity be determined by multiple runs, each run varying a single parameter? 

Evaluation: MILDOS-AREA does not have a sensitivity feature.

Score: 0 Weighted Score: 0 

3.5.11 Probabilistic Analysis Capability (1) 

Criteria: Is there a probabilistic analysis version of the code available? 

Evaluation: MILDOS-AREA does not have a probabilistic analysis feature. 

Score: 0 Weighted Score: 0 

3.5.12 SC&A Familiarity (N/A) 

Criteria: To be used as a tiebreaker when the top two codes have a final score within 10% of 

each other. 

Evaluation: Although we have obtained and installed MILDOS-AREA for this Work 

Assignment, to date, SC&A has not had the opportunity to use MILDOS-AREA in any of our 

work. 

3.6 MEPAS with FRAMES 

3.6.1 Exposure Pathways Modeled (2) 

Criteria: Are all of the exposure pathways that are essential to this analysis included in the 

code? Additionally, does the code allow for exposures to different age groups (i.e., adults, teens, 

children, infants) and/or sexes to be calculated? 

Evaluation: MEPAS models inhalation, ingestion, external exposure and dermal contact. 

Score: 5 Weighted Score: 10 

3.6.2 Population Based Dose/Risk Capability (2): 

Criteria: Does the code allow for the calculation of a population dose/risk based on a sitespecific unique population distribution or does the code only allow the calculation of dose/risk 

based on a single defined receptor location? 

Evaluation: Similar to GENII, MEPAS within FRAMES can perform calculations for 

populations but must have population distributions that match the format of the meteorological 
WA 1-04, Task 3 31 SC&A – August 31, 2010

data and must be constructed in ASCII format by the user. Also like GENII, there do not appear 

to be any preloaded population files present with the software. 

Score: 3 Weighted Score: 6 

3.6.3 Dose Factors Used (1.75) 

Criteria: Does the code utilize dose conversion factors based on the most recent International 

Commission on Radiological Protection (ICRP) recommendations? 

Evaluation: Per the MEPAS website: “Health impacts from exposure to radiation are estimated 

using health effects conversion factors or USEPA slope factors... values are based on 

recommendation given in the BEIR V report (NAS 1990) and International Commission on 

Radiological Protection (ICRP) Publication 60 (ICRP 1990).” 

Score: 4 Weighted Score: 7 

3.6.4 Risk Factors Used (1.75) 

Criteria: Does the code utilize the most recent risk factors? 

Evaluation: Per the MEPAS website: “Two methods are available to estimate the risk of cancer 

fatalities: use of health- effects conversion factors and use of USEPA slope factors.” Slope 

factors are based on USEPA (U.S. Environmental Protection Agency). 1994. Health Effects 

Assessment Summary Tables FY 1994 - Supplement Number 2. EPA/540/R-94/114. Office of 

Emergency and Remedial Response, Washington, D.C. 

Score: 5 Weighted Score: 8.75 

3.6.5 Meteorological Data Processing (1.5) 

Criteria: Can the code process “raw” meteorological data, or does the meteorological data need 

to be pre-processed prior to being entered into the code? For example, does the code accept 

“raw” meteorological tower data, or does it accept joint frequency data, or does it only accept 

dispersion and deposition factors? 

Evaluation: MEPAS accepts joint frequency data as a user input. It has not been established 

whether modules exist in the MEPAS suite of tools to convert and analyze meteorological data in 

other formats, as GENII contains. 

Score: 4 Weighted Score: 6 

3.6.6 Source Term Calculation (1.5) 

Criteria: Can the code calculate radon releases, or must the releases be pre-calculated and 

entered into the code? 
WA 1-04, Task 3 32 SC&A – August 31, 2010

Evaluation: Contaminant releases are provided by the AFF file; it is not clear from associated 

documentation whether releases are manually input by the user. Inspection of example problems 

provided with code package, indicate that the release data are likely a user input. 

Score: 2 Weighted Score: 3 

3.6.7 Verification and Validation (1.25) 

Criteria: Is there a readily available V&V package that supports the code? Is the V&V package 

complete? Has there been independent (i.e., by someone other than the code’s developer) V&V 

performed? 

Evaluation: No V&V package has been located with the MEPAS documentation available on 

the main website, though certain documents that appear to benchmark the code are listed as a 

reference on the main site. 

Score: 4 Weighted Score: 6 

3.6.8 Ease of Use/User Friendly (1.25) 

Criteria: Is the code provided with a user interface that is intuitive and easy to understand and 

use? Alternatively, does the code require the user to manipulate structured input data files? 

Additionally, does the code have features not required for this analysis, but that might complicate 

its use? 

Evaluation: MEPAS functions within FRAMES which allows the code to run in conjunction 

with, and provide input to, other modeling codes (such as GENII). While this allows for more 

dynamic modeling efforts, the strict use of MEPAS is not as straightforward because of the 

complexity of integrating the different codes and executing the FRAMES system itself. 

Score: 1 Weighted Score: 1.25 

3.6.9 Documentation (1) 

Criteria: Is the code well documented? Are there User’s Manuals readily available? In 

addition to providing instructions as to how to use the code, are the mathematical models used by 

the code well documented? 

Evaluation: User manuals are presented in html form via the MEPAS website; no current 

hardcopy versions (PDF) have been located. Website contains methodology and equations used 

by the code. A user guide presenting data input processes or example problems was not located. 

Score: 3 Weighted Score: 3 
WA 1-04, Task 3 33 SC&A – August 31, 2010

3.6.10 Sensitivity Analysis Capability (1) 

Criteria: Does the code have the capability to perform sensitivity analyses on the input data, or 

must parameter sensitivity be determined by multiple runs, each run varying a single parameter? 

Evaluation: MEPAS does include a ‘Sensitivity and Uncertainty’ module as described in the 

following: “FRAMES is currently designed for deterministic environmental and human health 

impact models. The Sensitivity/Uncertainty Multimedia Modeling Module (SUM3) software 

product was designed to allow statistical analysis using the existing deterministic models 

available in FRAMES. SUM3 randomly samples input variables and preserves the associated 

output values in an external file available to the user for evaluation.” 

Score: 4 Weighted Score: 4 

3.6.11 Probabilistic Analysis Capability (1) 

Criteria: Is there a probabilistic analysis version of the code available? 

Evaluation: From the main MEPAS website: “MEPAS is implemented on a desktop computer 

with a user-friendly interface that allows the user to define the problem, input the required data, 

and execute the appropriate models for both deterministic and probabilistic analyses.” 

Score: 4 Weighted Score: 4 

3.6.12 SC&A Familiarity (N/A) 

Criteria: To be used as a tiebreaker when the top two codes have a final score within 10% of 

each other. 

Evaluation: Although we have obtained and installed FRAMES-based MEPAS for this Work 

Assignment, to date, SC&A has not had the opportunity to use FRAMES-based MEPAS in any 

of our work. 
WA 1-04, Task 3 34 SC&A – August 31, 2010

4.0 RESULTS AND RECOMMENDATIONS 

Table 2 summarizes the results of the code evaluation as presented in Section 3. As shown, 

RESRAD-OFFSITE was the highest scoring of the five codes, narrowly edging out CAP88. 

However, it is recommended that CAP88, and not RESRAD-OFFSITE, be used to perform the 

dose and risk calculations required for this Work Assignment. The reasons for this 

recommendation include: 

• RESRAD-OFFSITE does not include the ability to perform population dose and risk 

estimates, which means that the RESRAD-OFFSITE results would need to be 

supplemented with population dose and risk estimates from another source. CAP88, on 

the other hand, is specifically designed to assess radiological emissions to the public. 

• The major area where CAP88 is lacking is sensitivity and probability analyses. For this 

Work Assignment, it is not anticipated that sensitivity or probability analysis will play a 

major role. 

• RESRAD-OFFSITE incorporates CAP88 air dispersion modeling, which means that 

there are no significant technical differences between the two codes for the purpose of 

this Work Assignment. 

• CAP88 was developed as a predecessor to AIRDOS, which was the original code used in 

the evaluation of mill tailing impoundments during the development of NESHAPs for 

radon emissions in 1989. 

GENII also finished high in the detailed evaluation; however, the main concern with GENII is 

that it currently is only available within FRAMES. As stated in Section 2.3.1, it was found that 

the process necessary to setup and run GENII within FRAMES was complicated relative to 

setting up and running pre-FRAMES GENII, and the present FRAMES GENII combination does 

not provide any technical advantage over the pre-FRAMES GENII. There are similar concerns 

regarding using MEPAS within FRAMES. The concern with FRAMES resulted in both GENII 

and MEPAS receiving low Ease of Use/User Friendly scores, which resulted in neither of them 

being selected for use. 

MILDOS-AREA received the lowest ranking in the detailed evaluation, primarily due to its 

inability to perform risk calculations, which is a major component of this Work Assignment. 

Although it does not impact this Work Assignment, MILDOS-AREA is limited to evaluating 

only the isotopes of the U-238 decay series, which means that another code would be required if 

other nuclear fuel cycle facilities were to be evaluated, such as was done in the 1989 analysis. 
WA 1-04, Task 3 35 SC&A – August 31, 2010

Table 2. Summary of Suitability Review for Five Codes Under Evaluation 

Evaluation 

Criteria CAP88 GENII via FRAMES 

RESRADOFFSITE MILDOSAREA MEPAS via 

FRAMES 

Exposure 

Pathways Modeled 10 10 10 10 10 

Population Dose/

Risk Capability 10 6 0 8 6 

Dose Factors Used 8.75 7 8.75 3.5 7 

Risk Factors Used 8.75 8.75 8.75 0 8.75 

Meteorological 

Data Processing 7.5 7.5 7.5 6 6 

Source Term 

Calculations 3 3 6 3 3 

Verification and 

Validation 6.25 6.25 6.25 6.25 5 

Ease of Use/

User Friendly 6.25 1.25 5 6.25 1.25 

Documentation 5 5 5 5 3 

Sensitivity 

Analysis Capability 0 4 5 0 4 

Probabilistic 

Analysis Capability 0 3 4 0 3 

Totals 65.5 61.75 66.25 48 57 
WA 1-04, Task 3 36 SC&A – August 31, 2010

5.0 REFERENCES 

Argonne National Laboratory (ANL), 1998, MILDOS-AREA User’s Guide (Draft), 

Environmental Assessment Division, September. 

Beres, D.A., 1990, The Clean Air Act Assessment Package-1988 (CAP-88) A Dose and Risk 

Assessment Methodology for Radionuclide Emissions to the Air, S. Cohen and Associates. 

Prepared for U.S. Environmental Protection Agency, October. 

Eckerman, K.F and Ryman, J.C, 1993, External Exposure to Radionuclides in Air, Water, and 

Soil – Federal Guidance Report No. 12, U.S. Environmental Protection Agency, 

EPA-402-R-93-081, September. 

Fields, D.E.; Miller, C.W.; Cotter, S.J, 1984, Validation of the AIRDOS-EPA Computer Codes by 

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