Tools for Assessing Radiological Doses to Human and Biota : Tools for Assessing Radiological Doses to Human and Biota
Charley Yu, PhD, CHP Argonne National Laboratory
Presented at the 2007 HPS Professional Development School
Corvallis, Oregon July 15, 2007
Presentation Outline : Presentation Outline Introduction
Dose Assessment Tools
RESRAD Family of Codes
Human Dose Assessment
Radionuclide transport in environment
External, inhalation, and ingestion pathways
Dose and risk coefficients
Exposure and transport parameters
Biota Dose Assessment
Dose limits
Reference animals and plants
Dose conversion coefficients
Bioaccumulation and allometric methods
Demonstration of RESRAD codes
Radiological protection standards have been formulated on the basis of potential risks to human : Radiological protection standards have been formulated on the basis of potential risks to human Dose or dose limits/constraints for human (mrem or mrem/yr):
5000 Worker dose
~300 Background radiation
100 Public dose
25 NRC cleanup level
15 EPA proposed cleanup level
10 NESHAPS air dose limit
~5 Chest X-ray
4 EPA drinking water limit
~3 Air travel for 3000 miles
1 IAEA clearance level
~1 Watch color TV for one year
Note: 1 mrem = 10 uSv
Software Tools for Dose Assessment Have Been Significantly Improved Over the Years : Software Tools for Dose Assessment Have Been Significantly Improved Over the Years Partially due to the invention of personal computers and advances in computer technology
Dose assessment tools are now more user-friendly
Easy to use with on-line help
Allows for error-checking (within parameter bounds)
Results are shown in graphical output and text report
Can be exported to spread sheets or text reports
Example Software Tools for Dose Assessment : Example Software Tools for Dose Assessment CAP88 (models dose from radioactive air emmission)
COMPLY (atmospheric screening model)
DandD (decommissioning and decontamination screening model)
DCAL (calculates tissue dose from intake and exposure to radionuclides in the environment)
DUST (a disposal unit source term model)
GENII (models the dose from chronic and acute releases)
MEPAS (used for multimedia transport of chemicals and radionuclides)
PRESTO (models low level waste)
RESRAD Family of Codes (Used for various applications ranging from cleanup of contaminated sites, to assessment of waste disposal facility performance, to dose assessment for animals and plants)
Similarities and Differences Among Software Tools : Similarities and Differences Among Software Tools Although they are designed for different applications, all of them rely on the same basic theory of radionuclide transport in the environment
Advection and dispersion
Ingrowth and decay
Dose conversion coefficients
Potential differences include:
Assumptions made in the code
Pathways included
Parameters used
Method used in solving mathematical equations
Design of code may be different (user-friendliness, error checking, on-line help)
RESRAD Family of Codes : RESRAD Family of Codes
Calculation of Radiological Doses to Human — Using RESRAD (onsite) Methodology as an Example : Calculation of Radiological Doses to Human — Using RESRAD (onsite) Methodology as an Example
What is RESRAD (onsite)? : What is RESRAD (onsite)? RESRAD is a computer code developed at Argonne to calculate:
Site-specific RESidual RADioactive material guidelines (cleanup criteria or DCGLs), and
Radiation dose and excess lifetime cancer risk to an on-site resident (a maximally exposed individual or a member of a critical population group)
RESRAD Code Considers All Pathways : RESRAD Code Considers All Pathways Nine major environmental pathways are available in RESRAD
External (Ground)
Inhalation
Particulates
Radon
Ingestion
Soil
Water
Plant
Meat
Milk
Aquatic Foods
Exposure Pathways for a Subsistence Farming Scenario : Exposure Pathways for a Subsistence Farming Scenario
Exposure Pathways for a Industrial Use Scenario : Dust,
Radon Drinking
Water Soil
Ingestion Infiltration Leaching External Groundwater Exposure Pathways for a Industrial Use Scenario Surface
Water
Analysis of Multiple Scenarios : 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
Both onsite and offsite receptors in RESRAD-OFFSITE
Major Features of RESRAD : Major Features of RESRAD Probabilistic input/output interface
Conventional (pCi and mrem) and SI (Bq, Sv) units
Latest risk databases (FGR 13 morbidity and mortality and HEAST 2001 morbidity)
Comprehensive external gamma dose model
Ground-water transport model for decay chains
Expanded radionuclide database (838 radionuclides) with user selected cut-off half-life
Major Features of RESRAD (continued) : Major Features of RESRAD (continued) Five output reports (Summary, Detailed, Health Risk, Concentration, Daughter Contributions)
New radionuclide uptake and transfer factor database
Time integrated dose and risk
Ability to create and edit DCF, risk coefficients, and plant, meat, milk, and fish transfer factors
Shared databases with other RESRAD family of codes
Dose Conversion Factors : Dose Conversion Factors External exposure pathway:
infinite depth volume factors (mrem/yr per pCi/g)
area, depth, and shape correction factors
Inhalation pathway:
inhalation factors for adults
age-dependent DCFs in RESRAD-OFFSITE
Ingestion pathways
ingestion factors
age-dependent DCFs in RESRAD-OFFSITE
References:
External DCFs - Federal Guidance Report No.12 (1993)
Inhalation/Ingestion DCFs - FGR No.11 (1988),
Age-dependent DCFs: ICRP 72 (1996)
Cancer Slope Factors : Cancer Slope Factors 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.
Source Mass Balance : Source Mass Balance Mass balance is maintained between the contaminated source and each transport pathway
RESRAD keeps track of source losses from radioactive decay, leaching, and erosion
RESRAD accounts for ingrowth of daughters from initially present parent radionuclides
RESRAD Parameter Database : 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
Site Specific Input Parameters : Site Specific Input Parameters Physical parameters (size, depth, density, porosity, diffusion coefficient)
Hydrological parameters (hydraulic conductivity, gradient, soil b parameter, and dispersivity)
Geochemical parameters (distribution coefficient, leach rate, solubility)
Meteorological parameters (precipitation, evapotranspiration, and dispersion coefficients)
Usage and consumption parameters (inhalation, irrigation, ingestion, occupancy)
RESRAD Calculates the Dose to Source Ratio : RESRAD Calculates the Dose to Source Ratio
Calculation of the Dose to Source Ratio : Calculation of the Dose to Source Ratio DSRip (t) =
DCFjp = dose conversion factor (mrem/yr per pCi/g or mrem/pCi)
BRF = branching factor (dimensionless)
ETFjp (t) = environmental transport factor (dimensionless or g/yr)
SFij (t) = source factor for ingrowth, decay and leaching (dimensionless)
Dose Conversion Factor/Risk Factor Libraries : Dose Conversion Factor/Risk Factor Libraries Using the Dose Conversion Factor Editor
Users can modify DCFs
Select a more appropriate DCF
Create a new DCF
Users can modify Slope factors
HEAST 2001
FGR 13 Morbidity
FGR 13 Mortality
User Specified
Source Factors : Source Factors Ingrowth of principal radionuclide j from principal radionuclide i, assuming associate radionuclides are in secular equilibrium with their principal radionuclides
Accounts for radioactive decay and leaching See Appendix G for more details
Factors Affecting Source Loss : Factors Affecting Source Loss
Environmental Transport Factors: External Ground : Environmental Transport Factors: External Ground Appendix A: RESRAD users manual
FO1 = occupancy and shielding factor
FSi1 = shape factor
FAi1(t) = nuclide specific area factor
FCDi1(t) = depth and cover factor
Occupancy and Shielding Factor : Occupancy and Shielding Factor Comprised of
fotd;: Fraction of time spent outdoors
find : Fraction of time spent indoors
Fsh: External gamma shielding factor
Fsh is radionuclide INDEPENDENT Default Case
Fsh =0.7
meaning that the indoor radiation level is 70% of outdoor level
Depth and Cover Factor : Depth and Cover Factor Allows users to enter
Any contaminated zone thickness, and density
Any one cover thickness and density
Based on a regression analysis of FGR 12 DCFs
FCD’s are radionuclide dependent
Examples of FCDs for Two Radionuclide (No Cover) : Examples of FCDs for Two Radionuclide (No Cover) FCD for Co-60
Variable Contaminated Zone Thickness
No cover
Infinite external DCF
16.2 mrem/yr / pCi/g FCD for U-234
Variable contaminated zone thickness
No cover
Infinite external DCF
4.02 x 10-4 mrem/yr / pCi/g
Examples of FCDs for Two Radionuclide : Examples of FCDs for Two Radionuclide FCD for Co-60
Contaminated Zone Thickness = 2m
Variable cover thickness FCD for U-234
Contaminated zone thickness = 2m
Variable cover thickness
Area Factor : Area Factor Radionuclide specific factor to correct an infinite geometry (FGR 12) to finite geometry (site-specific)
Performs point-kernel integration on the dose
Uses ICRP-38 photon spectra
Benchmarked against MCNP
Area Factor Calculation : Area Factor Calculation Co-60, Pu-240 Example
No cover
1 cm thick contaminated zone
Pu-240 infinite DCF
1.47 x 10-4 mrem/yr / pCi/g
Shape Factor: Non-Circular Shapes : Shape Factor: Non-Circular Shapes RESRAD allows users to construct non- circular shaped sources
Allows users to place receptors anywhere on the source
Biggest Impact on long rectangular sources
Roads
Railroad right a way
Primarily affects the external pathway
Environmental Transport Factors: Inhalation Pathway : Environmental Transport Factors: Inhalation Pathway Appendix B: RESRAD users manual
ASR2 = mass loading factor
(air/soil concentration ratio)
FA2 = area factor
FCD2(t) = cover and depth factor
FO2 = occupancy factor
FI2 = annual intake of air
Contaminated Zone Mixing Layer
Area Factor for Inhalation : Area Factor for Inhalation Ratio of airborne concentration from a finite area source to the airborne concentration of an infinite source.
Empirical model based on least square regression.
Inversely proportional to square root of the Area
Fit parameters are correlated to wind speed
Occupancy Factor : Occupancy Factor Methodology identical to that used for the external pathway
Indoor dust filtration factor (Fdust)
0.4 default
Meaning that indoor concentration is 40% of the outdoor concentration
Ingestion Pathways : Ingestion Pathways Water independent
Not dependent on contaminated ground water and/or surface water
Deposition on leaves
Root uptake from soil contamination
Water dependent
Water used for
Drinking
Irrigation
Livestock Feed
What about dose to animals and plants?
Environmental Transport Factors: Soil Ingestion : Environmental Transport Factors: Soil Ingestion Appendix F: RESRAD users manual
Models the incidental ingestion of soil
FSI = annual intake of soil
FA8 = area factor
FCD8(t) = cover and depth factor
Same model as inhalation pathway
FO8 = occupancy factor
Total time spent on the site
Indoor time fraction + outdoor time fraction
Area Factor: Soil Ingestion : Area Factor: Soil Ingestion Fraction of work area that might be contaminated
A is the area of contaminated zone and 1,000 m2 is the assumed play or work area which is approximately the size of a single house lot
Environmental Transport Factors: Plant Meat and Milk Pathways : Environmental Transport Factors: Plant Meat and Milk Pathways Appendix D: RESRAD users manual
Where
DF = dietary factor (annual consumption rate)
FSR(t) = food/soil concentration ratio
FA = area factor
FCD(t) = cover and depth factor
Area Factor: Plant, Meat & Milk Ingestion : Area Factor: Plant, Meat & Milk Ingestion Plant Ingestion
User override
Meat and Milk Ingestion
User override Area required to grow plants or raise livestock
Cover and Depth Factor: Direct Root Uptake : Cover and Depth Factor: Direct Root Uptake Fraction of root length in the contaminated zone
Uncontaminated
Cover Contaminated
Zone
Water Pathway Factors : Water Pathway Factors Appendix E: RESRAD users manual
Radionuclide Transport in Groundwater : Radionuclide Transport in Groundwater Transport Mechanisms
Advection
Dispersion
Adsorption/desorption
Radiological decay and ingrowth
Methods of Solution
Analytical
Semi-analytical
Numerical
Leaching Model : Leaching Model Sorption-desorption ion-exchange model
Contaminated Zone Unsaturated Zone Runoff Precipitation Evapo-transpiration Irrigation
Leaching Model : Leaching Model Note: Rs ≤ 1
Ksat ≥ I
Leaching Model : Leaching Model
Radionuclide-specific KD
Hydraulic conductivity (m/yr)
0.02 [Loam]
to 5,500 [Sand]
Soil-specific “b” parameter
4.0 [Sand]
to 11.4 [Clay]
Field capacity
Lower limit of volumetric water content
See Data Collection Handbook for more information
Summary of Human Dose Assessment : Summary of Human Dose Assessment Source Term
Radionuclide Transport in the Environment
Decay and Ingrowth
Inhalation and Ingestion
External Exposure
Dose and Risk Coefficients
Occupancy Factor
Exposure Scenarios and Parameters
Sensitivity and Uncertainty Analysis
RESRAD Supporting Documents : RESRAD Supporting Documents User’s Manual for RESRAD Version 6, ANL/EAD-4, July 2001
RESRAD Parameter Sensitivity Analysis [8/91]
Data Collection Handbook to Support Modeling the Impacts of Radioactive Material in Soil [4/93]
A Compilation of Radionuclide Transfer Factors for the Plant, Meat, Milk and Aquatic Food Pathways and the Suggested Default Values for the RESRAD Code [8/93]
Verification of RESRAD [6/94]
RESRAD Benchmarking Against Six Radiation Exposure Pathway Models [10/94]
External Exposure Model Used in the RESRAD Code for Various Geometries of Contaminated Soil [9/98]
Evaluation of Area Factor for Finite Area Sources for Inhalation Dose Calculations [7/98]
Development of Probabilistic RESRAD 6.0 and RESRAD-BUILD 3.0 Computer Codes [11/00]
Calculation of Radiological Doses to Biota — Using RESRAD-BIOTA Methodology as an Example : Calculation of Radiological Doses to Biota — Using RESRAD-BIOTA Methodology as an Example
Increasing Interest in Radiation Protection of the Environment : Increasing Interest in Radiation Protection of the Environment Revisiting ICRP assumption
Different exposure pathways
Site, regulator, and stakeholder interest
International activity
IAEA
ICRP
Other Countries
The Evolving ICRP Position on the Protection of the Environment : The Evolving ICRP Position on the Protection of the Environment “…if man is adequately protected then other living things are also likely to be sufficiently protected.” (ICRP Pub. 26, 1977)
“The Commission believes that the standards of environmental control needed to protect man to the degree currently thought desirable will ensure that other species are not put at risk.” (ICRP Pub. 60, 1991)
“Occasionally, individual members of non-human species might be harmed, but not to the extent of endangering whole species or creating imbalance between species.” (ICRP Pub. 60, 1991)
“…ICRP therefore needs to revise its current system of protection, and particularly, develop a comprehensive approach to the study of the effects on, and protection of, all living matter with respect to the effects of ionising radiation…” (ICRP Pub. 91, 2003)
Slide53 : The Proposed Common ICRP Approach Reference Man Environmental radionuclide concentration(s) Reference Animals
and Plants Dose limits, constraints Decision-making regarding public health and environment for the same environmental situation Derived Consideration Levels Normal situations, accidents and existing exposures 53
Reference Animals and Plants (RAPs) : Reference Animals and Plants (RAPs) Deer
Rat
Bee
Earthworm
Duck
Frog
Trout
Marine Flatfish
Crab
Pine Tree
Grass
Seaweed
Evolution of Dose Limits for Biota : Evolution of Dose Limits for Biota Historical setting:
Human limits are dose-based
Protection established by examining all exposure pathways
1990’s DOE considered parallel protection for biota
DOE Standard (DOE Order 5400.5):
1 rad/d (10 mGy/d) for aquatic organisms
Dose Limits for Biota : Dose Limits for Biota Based on NCRP and IAEA findings
Other standards proposed
10 CFR 834, Subpart F:
1 rad/d for aquatic animals
1 rad/d for terrestrial plants
0.1 rad/d for terrestrial animals
Comparison of Acute Lethal Dose Ranges : Comparison of Acute Lethal Dose Ranges Approximate acute lethal dose ranges for various taxonomic groups. Adapted from Whicker & Schultz (1982).
Scientific Basis for Biota Dose Limits : Scientific Basis for Biota Dose Limits IAEA Report 172 (1976) Effects of Ionizing Radiation on Aquatic Organisms and Ecosystems
ICRP Report 26 (1977) Recommendations of the International Commission on Radiological Protection
NCRP Report 109 (1991) Effects of Ionizing Radiation on Aquatic Organisms
IAEA Report 332 (1992) Effects of Ionizing Radiation on Plants and Animals at Levels Implied by Current Radiation Protection Standards
DOE Workshop Report (1995) Effects of Ionizing Radiation on Terrestrial Plants and Animals
UNSCEAR (1996) Sources and Effects of Ionizing Radiation; pers. com. 2002 & 2003
ACRP Report INFO-0730 (2002) Protection of Non-Human Biota From Ionizing Radiation
UK Environment Agency R&D Publication 128 (2002) Impact Assessment of Ionizing Radiation on Wildlife
ICRP Report 91 (2003) A Framework for Assessing the Impact of Ionising Radiation on Non-human Species
Basic Screening Methodology: Biota Concentration Guides (BCGs) : Basic Screening Methodology: Biota Concentration Guides (BCGs) Dose Limit
BCG =
Internal Dose + External Dose
Evaluate for unit concentration (e.g., 1 Bq kg-1) for single media (e.g., soil)
Use sum of fractions approach for multiple media (e.g., sediment, water) and radionuclides
Conservative assumptions and default parameters
DOE’s Graded Approach : DOE’s Graded Approach Compare media concentrations with
Biota Concentration Guides
(BCGs) (RESRAD-BIOTA Level 1) Site-representative parameters
(RESRAD-BIOTA Level 2) Data
Assembly General
Screening Analysis Site Specific
Screening Site Specific
Analysis Site Specific
Biota Dose
Assessment Kinetic/allometric modeling tool
(RESRAD-BIOTA Level 3) Collection of biota using
eco-risk protocols
Receptors Used in Deriving the Screening Methodology : Receptors Used in Deriving the Screening Methodology BCGs Riparian Animal Terrestrial Animal Aquatic Animal Terrestrial Plant
DOE Biota Technical Standard : DOE Biota Technical Standard MODULE 1: Principles and Applications (users guide)
Overview of the graded approach & evaluation process
Application considerations
Look-up tables; step-by-step guidance; RAD-BCG Calculator
Examples
MODULE 2: Detailed Guidance (links to users guide)
Radiological ecological risk assessment: tutorial & issues
Time averaging and spatial variability (contaminants & doses)
Defining the evaluation area
Biota sampling design and methods
Radiation weighting factor for alpha particles
Evaluation of individuals; special considerations
MODULE 3: Methods Derivation (links to users guide)
Equations and models for deriving BCGs / default parameters
Download: http://homer.ornl.gov/nuclearsafety/nsea/oepa/bdac/biota/
RAD-BCG Calculator : RAD-BCG Calculator Encodes Method
Microsoft Excel®
Visual Basic®
Contact:
Kathryn A. Higley, PhD, CHP
Dept. of Nuclear Engineering
& Radiation Health Physics
Oregon State University
541.737.0675
kathryn.higley@oregonstate.edu
RESRAD-BIOTA is the “Next Generation” Tool for Biota Dose Evaluation : RESRAD-BIOTA is the “Next Generation” Tool for Biota Dose Evaluation The RAD-BCG Calculator (Microsoft Excel-based) is approaching the limits of it’s software platform capabilities
The RESRAD platform was selected because:
It has a highly-regarded pedigree: QA and validation studies
It is widely recognized and implemented within DOE, other U.S. Federal and State agencies, and the U.S. nuclear industry
Can leverage & link RESRAD capabilities with RESRAD-BIOTA
It provides the software architecture and degree of sophistication needed for expanding upon DOE’s biota methods and capabilities; and for being responsive to the needs of a broader community of users
Development of RESRAD-BIOTA : Development of RESRAD-BIOTA Code development initiated by DOE in June 2000
Principally developed and sponsored by DOE since 2000; DOE then formed the ECORAD-Workgroup, an inter-agency group consisting of DOE, the Environmental Protection Agency (EPA), and the Nuclear Regulatory Commission (NRC) to continue code development in collaboration
RAD-BCG Calculator successfully converted into beta version of RESRAD-BIOTA in 2001
Added sensitivity analysis capability in 2002
Generated dose conversion factors for 8 organisms in 2003
Designed a new user interface with Organism Editor in 2003
A total of 46 radionuclides in the current database
Features of RESRAD-BIOTA : Features of RESRAD-BIOTA Reproduces RAD-BCG results
Has a user-friendly input interface with Help files
Users can view dose conversion factors (DCFs), dose results, BCG results, etc., and select radiological units
User can modify lumped parameters (B values and Kds), dose limits, area factors, radiation weighting factors, DCFs, and allometric parameters, etc.
Shows screening results (pass or fail) and have text reports and bar charts
Users can do sensitivity analysis on input parameters
RESRAD-BIOTA Main Window : RESRAD-BIOTA Main Window
Parameter Access vs Level : Parameter Access vs Level
Assumptions for Level 1 External Dose : Assumptions for Level 1 External Dose Source medium infinite/semi-infinite in extent and contains uniform concentrations of radionuclides
Extremely small organism
Source & receptor geometry: water & sediment soil
Assumptions for Level 1 Internal Dose : Assumptions for Level 1 Internal Dose Extremely large organism
All decay energies retained in tissue
Chain-decay progeny included
Radiation weighting factor included (and modifiable)
Nuclides uniformly distributed
Internal Dose Factors : Internal Dose Factors Where the following terms apply:
DCFInternal,i = Gy/y per Bq/kg of wet tissue for radionuclide i;
Yj = yield (abundance) of radiation j per disintegration of nuclide i;
Ej = energy (MeV) of radiation j for nuclide i; and
Qj is the radiation weighting factor (quality factor) for radiation j of nuclide i.
Deriving Limiting Concentrations : Deriving Limiting Concentrations DCFinternal (Gy y -1/ Bq kg-1) is the dose conversion factor for radionuclides in the tissue of the organism;
LP is a parameter which relates radionuclide concentration in the media external to the organism to its internal tissues;
DCFexternal (Gy y -1/ Bq kg-1) is the dose conversion factor for radionuclides in the media external to the organism;
Lumped Parameters : Lumped Parameters Measures degree of radionuclide transport in an ecosystem
Sometimes called
Concentration ratio
Concentration factor
Transfer factor, or
Wet-weight concentration ratio (BiV)
Lumped Parameter Dataset : Lumped Parameter Dataset
Addressing Data Gaps : Addressing Data Gaps Lumped Parameters (LPs)
Empirical data
Product approach
Calculational method called “kinetic/allometric”
Lessons learned in method development:
Less data available than we originally thought
Continuously “reality checking” with site applications
Kinetic Approach, Internal Exposure : Kinetic Approach, Internal Exposure Input Rate Loss Rate Body
Burden
Kinetic Approach, Body Burden Estimates : Kinetic Approach, Body Burden Estimates time q Function of:
Body mass
Intake rate
Loss rate
Exposure time
Need to address:
varying mass
intake
exposure period
Allometric Relationships : Allometric Relationships Cross-species relationships
Y = aXb
Empirically obtained
Derived from energy/nutrient transport limitations
Mass and Metabolic Rate
M3/4 (Ingestion, Inhalation)
M1/4 (Life-span)
aMx (biological elimination rate)
Mass and Home Range
M~3/4 (Defining exposure areas)
Combining Kinetic & Allometric : Combining Kinetic & Allometric Allows prediction of body burden
for any body mass
lifespan
loss rate
Can be tailored to specific species
Stochastic analysis used to ground truth approach and compare to “lumped” parameters
RESRAD-BIOTA: Key Features : RESRAD-BIOTA: Key Features Duplicates DOE Graded Approach process & BCGs
Retains flexibility to modify organism exposure profile, parameters, dose limits, allometric relationships
Like the Graded Approach, the code implements primary and secondary reference organism concepts
Organism Wizard allows users to configure their own “secondary” organisms
Includes DCFs for 8 specific geometries covering a wide range of organisms
Sensitivity analysis
Import and export data
Procedure for Deriving Level 3 DCFs : Procedure for Deriving Level 3 DCFs Calculate absorbed fractions for photons and beta particles (electrons) of different energies for different organisms (dimensions) using MCNP
Calculate effective absorbed beta and photon fraction for each radionuclide
The absorbed fraction for alpha radiation for all geometries is assumed unity
Absorbed fractions for default geometry is also calculated. Default geometry is infinitely large for internal DCF and infinitesimally small for external DCF
Comparison of absorbed fractions with available data
Calculate internal and external DCFs
DCF Methodology : DCF Methodology Y = Nuclide yield
n = number of nuclides (parent + associated)
type = electron, photon, alpha
k = 5.04E-6 (unit conversion factor) (Gy/y per Bq/kg) per (MeV/Bq-s)
E = energy in MeV
r = radiation identification
y = radiation yield
ftype(Er,org) =
Fraction absorbed (F) for internal DCF
(1-F) for external DCF
1 for both internal and external for default organisms
International Biota Dose Assessment Activities and Resources : International Biota Dose Assessment Activities and Resources IAEA EMRAS Biota Working Group
EU EURATOM PROTECT Project
FREDERICA Radiation Effects Database
ERICA (Environmental Risk from Ionising Contaminants: Assessment and Management) Assessment Tool
IAEA TRS 364 Handbook
Summary of Biota Dose Assessment : Summary of Biota Dose Assessment Radionuclide Concentration in the Environment
Radionuclide Concentration in Biota
Lumped Parameter Transfer factors (Biv, etc)
Dynamic/Allometric Method
Reference Animals and Plants
External and Internal Exposures
Dose Conversion Coefficients
Home Range Consideration
Sensitivity and Uncertainty Analysis