1. RESRAD Program Manager Environmental Science Division
RESRAD-OFFSITE Code and Derivation of Cleanup Criteria Presented at EMRAS II NORM & Legacy Sites WG Meeting
Charley Yu, PhD, CHP
RESRAD Program Manager
Environmental Science Division
January 27, 2010

2. RESRAD Development Timeline

3. RESRAD Family of Codes

4. EXPOSURE PATHWAYS CONSIDERED IN RESRAD (Subsistence Farming Scenario)
Dust,
Radon
Drinking
Water
Fish
Plant
Foods
Meat
Milk
Radioactively Contaminated Material in Soil
Soil
Ingestion
Infiltration
Leaching
External
Surface
Groundwater

5. EXPOSURE PATHWAYS CONSIDERED IN RESRAD (Industrial Use Scenario)
Drinking
Water
Dust,
Radon
Soil
Ingestion
Infiltration
External
Radioactively Contaminated Material in Soil
Leaching
Surface
Water
Groundwater

6. Pathway Analysis - nine environmental pathways
RESRAD PATHWAYS
Pathway Analysis - nine environmental pathways
Direct Exposure
Inhalation
Ingestion of plant foods
Ingestion of meat
Ingestion of milk
Ingestion of aquatic foods
Ingestion of water
Ingestion of soil
Radon

7. SINGLE RADIONUCLIDE GUIDELINE
RESRAD calculates homogeneous soil guidelines (DCGL’s) for each radionuclide specified by the user for the applicable exposure pathways
Guidelines are concentrations of radionuclides in soil for which the basic dose limit will not be exceeded over the selected time horizon (usually 1000 years following remedial action) 11

8. RADIOLOGICAL RELEASE CRITERIA
HE (t) < HEL
HE (t) = dose from all pathways (mSv/year)
HEL= basic dose limit
= 0.25 mSv/year

9. SINGLE RADIONUCLIDE GUIDELINE
Gi = minimum Gi (t) for t < 1000 years
Gi (t) =
DSRi (t) =
= dose/source concentration ratio for radionuclide i at time t (mSv/year per Bq/g)

10. DOSE CONVERSION FACTORS
External exposure pathway:
- infinite depth volume factors (mrem/yr per pCi/g)
Inhalation pathway:
- inhalation factors
Ingestion pathways
- ingestion factors
References: External DCFs - Federal Guidance Report No.12 (1993) Inhalation/Ingestion DCFs - FGR No.11 (1988)

11. SLOPE FACTORS USED IN RESRAD
Units of Sfj,p:
For external radiation -- risk/yr per pCi/g
For inhalation and ingestion pathways-- risk/pCi
Source of Sfj,p:
EPA publications -- HEAST (2001)
Federal Guidance Report # 13 (1999)
Morbidity
Mortality
Note: Values of Sfj,p include contributions from associate decay products with half-lives < cutoff, which are assumed to be in equilibrium with their parent principal radionuclide.

12. ANALYSIS OF MULTIPLE SCENARIOS
Current use and plausible future use scenarios can be easily simulated
One or more exposure pathways may be added or suppressed
Occupancy factors and consumption parameters may be tailored according to the scenario being simulated
Typical exposure scenarios include industrial, recreational, residential, and subsistence farming
The next three slides expand the second bullet from the “Major Features” slide. This slide tells the audience that RESRAD is a flexible code that can be used under different land use assumptions. I will mention that the demonstratation will show the flexiblity of the code in activating or suppressing pathways and modifying data for a number of scenarios. 16

13. Leaching model: sorption-desorption ion exchange
WATER PATHWAY MODELS
Leaching model: sorption-desorption ion exchange
- Input of distribution coefficient (Kd)
- Input of groundwater concentration
- Input of solubility limit
- Input of leach rate
- Correlation of Kd with soil-plant transfer factors
Independent transport of daughter radionuclides
Radionuclide transport models:
Nondispersive flow or mass balance
The next two slides expand the fourth bullet from the “Major Features” slide. This slide summarizes the leaching/transport mechanisms for radionuclides in the water pathway. 21

14. SPECIAL MODEL FOR RADON
Radionuclides:
- radon-222 and progeny
- radon-220 (thoron) and progeny
Multimedia radon transport:
- soil
- water
- building materials
Ingrowth from parents:
- Uranium and thorium series
The next two slides expand the fifth bullet from the “Major Features” slide. This slide highlights the special model used for the radon pathway. The last bullet is to inform the audience that the radon pathway may be activated if any precursor radionuclides are entered as soil contaminants. I will mention that the demonstration will show this feature. 24

15. RESRAD PARAMETER DATABASE
Decay and ingrowth data
Dose conversion factors
Cancer slope factors
Food transfer factors (plant/soil, meat/feed, milk/feed, fish/water)
All 838 radionuclides contained in ICRP-38 are in RESRAD database (New DECDATA >1200 radionuclides are being included)
The next four slides expand the sixth bullet from the “Major Features” slide. This slide highlights the “not-so-site-specific” parameters in the RESRAD data base. I will mention that the demonstration will show how to access some of these parameters. 26

16. SITE SPECIFIC INPUT PARAMETERS
Physical parameters (size, depth, density, porosity, diffusion coefficient)
Hydrological parameters (hydraulic conductivity, gradient, soil b parameter, water table depth)
Geochemical parameters (distribution coefficient, leach rate, solubility)
Meteorological parameters (precipitation, evapotranspiration, erosion, runoff, mass loading
Usage and consumption parameters (inhalation, irrigation, ingestion, occupancy)
This slide will give the audience and idea of the major categories of site-specific input parameters (along with examples in each category). I will indicate that not all parameters are accessible to the user, only the ones that are relevant to active pathways used in the scenario being modeled. I will mention that the demonstration will show how to access these parameters. 28

17. PROBABILISTIC RESRAD Codes
Developed probabilistic modules for RESRAD (onsite) (6.0), RESRAD-BUILD (3.0), and RESRAD-OFFSITE (2.0)
Identified key parameters and compiled parameter distribution data for probabilistic analysis
Developed integrated RESRAD codes to perform probabilistic dose assessment for site-specific analysis
Developed postprocessor to analyze and display probabilistic results

18. PROBABILISTC vs. DETERMINISTIC ANALYSIS

19. COMPILATION OF PARAMETER DISTRIBUTIONS WAS A MAJOR EFFORT

20. Derivation of Site-specific Cleanup Criteria
Discussion of RESRAD application: Elza Gate uranium guidelines, Toscanini at the controls of remedial action equipment, ALARA application, etc. 39

21. Procedures to Determine & Apply Site-Specific Guidelines
Determine exposure scenario(s)
Determine exposure pathway(s)
Gather data
Understand calculations
Calculate guidelines
Set cleanup criteria for the site
Cleanup
Postremediation dose assessment
Use RESRAD Family of Codes

22. Exposure scenarios may be classified as:
Expected
Plausible
Unlikely
Typical exposure scenarios:
Industrial use
On-site resident (variations: suburban or subsistence farmer)
Recreational use 41

23. NATURAL URANIUM CLEANUP CRITERIA CONSIDERATION
The activity-based weighting factors for natural uranium (wU-23*) are:
wU-234 = 1/2.046 = 0.489
wU-235 = 0.046/2.046 =
wU-238 = 1/2.046 = 0.489
102
102

24. RESIDUAL RADIOACTIVE MATERIAL GUIDELINES FOR THE ELZA GATE SITE
Guideline set by DOE: 70 pCi/g (2590 Bq/kg) Total Uranium
Guideline (pCi/g)*
Radionuclide
Uranium-234
Uranium-235
Uranium-238
Uranium-Tot
Scen. A
2400
450
1600
1800
Scen. B
5400
1100
3600
4000
Scen. C
590
150
430
470
Scen. D
120 47
A = Industrial-use scenario (current use)
B = Recreationist
C = Residential-use scenario (pond water)
D = Residential-use scenario (well water)
* Based on dose limit of 1 mSv/yr 42

25. Application of DOE’s ALARA Policy
Note: volume estimate based on DOE’s residual contamination guidelines for Ra-226, Th-230, Th-232, and a variable U-238 guideline.

26. Derivation of Soil Guidelines (DCGLs)
Dose Limit/ Constraint
(100 / 25 mrem/yr)
Operational DCGLs
Single Radionuclide DCGLs
Sum of Ratios
Regulations
Pathway Analysis
Field Implementation

27. POSTREMEDIATION DOSE ASSESSMENT FOR THE ELZA GATE SITE
Scen. A
1.5
Scen. B
0.66
Scen. C 12
Scen. D 42
A = Industrial-use scenario (current use)
B = Recreationist
C = Residential-use scenario (pond water)
D = Residential-use scenario (well water)
Dose Rate
(mrem/yr)
Average Radionuclide Concentrations:
4.9 pCi/g U-238 (measured)
4.9 pCi/g U-234, 0.22 pCi/g U-235 (derived) 43

28. Summary RESRAD has been in existence for more than 20 years
RESRAD is the most extensively tested, benchmarked, verified, and validated code in the environmental risk assessment and site cleanup field
RESRAD has been widely used by federal and state agencies and their contractors
Over 100 training workshops have been sponsored by DOE, NRC, EPA, DOD, and state agencies
Many universities have used RESRAD as a teaching and research tool
Many papers and theses have been published based on RESRAD (some in foreign languages)
RESRAD has been widely used nationally and internationally.
Comprehensive supporting documents are available for the application of RESRAD
RESRAD is continuously maintained and improved
RESRAD can be downloaded free of charge
This slide provides a list of the extensive RESRAD documentation and reinforces the fact that RESRAD is a well documented and “mature” code. The last bullet on this slide serves as an intro to the RESRAD-Probabilistic code (first bullet on the next slide). 35

29. Thank You! RESRAD Web Site: http://www.evs.anl.gov/resrad