Nick Beresford (CEH) & David Copplestone (Stirling Univ.)
RESRAD-BIOTA
RESRAD-BIOTA Code which implements the USDOE’s
Graded approach (replaces BCG-calculator) Part of the RESRAD suite of models Freshwater and terrestrial ecosystems Database contains 46 radionuclides Four organisms – terrestrial animal,
terrestrial plant, riparian animal and aquatic animal
Can create organisms & simple foodchains
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Availability and documentation
Available at no cost for download on-line Comparatively well documented Being maintained and upgraded Training available
RESRAD-BIOTA
www.ead.anl.gov/resrad/home2/
USDOE Graded Approach
BDAC
Series of paper in: Woodhead, D.S. (Ed.), 2003. Protection of the environment from ionising radiation. Journal of Environmental Radioactivity, 66.
www.ceh.ac.uk/PROTECT
RESRAD-BIOTA v’s ERICATerms used
Tiers are Levels CRs are Bivs EMCLs are BCGs (Biota Concentration
Guides) DCCs are DCFs (Dose Conversion Factor)
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RESRAD-BIOTA Level
USDOE - benchmarksBased on NCRP & IAEA set dose limits for protection of:
Aquatic animals - 10 mGy d-1
Terrestrial plants - 10 mGy d-1
Terrestrial animals - 1 mGy d-1
RESRAD-BIOTA - BCGsEstimated assuming: Infinitely large (internal) and small
(external) geometries for dose calculations Daughter T1/2’s up to 100 y included All terrestrial organisms 100% in soil;
aquatic 100% water-sediment interface ‘Maximum’ CR values or 95th percentile
CR values predicted using a kinetic-allometric approach
LEVEL 1
Screening assessment - Levels 1
Cs-137 water 10 Bq/l sediment 1000 Bq/kg
Am-241 sediment 1000 Bq/kg
Cf-252 water 1 Bq/kg
Use 10 µGy/h screening level (2.4E-4 Gy/d)
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Level 1
Run the freshwater and terrestrial scenarios from the ERICA Tier 1 practical Use ERICA screening value 10 µGy/h Leave out the radionuclides which are not
included in RESRAD
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Radionuclide Freshwater (Bq/l)H-3 4Co-60 0.3Cs-137 0.3Pu-239 0.04
Radionuclide Soil (Bq/kg)Cs-137 10Am-241 0.3Pu-239 170Co-60 0.1Sr-90 1.3
Level 2
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Level 2
Site specific CR values available for aquatic animal: Co 1500; Cs 9000; H 0.25; Pu 200
Radionuclide Freshwater (Bq/l)H-3 4Co-60 0.3Cs-137 0.3Pu-239 0.04
Level 3
RESRAD-BIOTA
Also uses CRs (or Bivs), but:
RESRAD-BIOTA
Soil contamination
Fugitive dust
Vegetation
Soil invertebrate
Herbivorous mammals
Herbivorous birds
Carnivorous mammals
Water
contamination
Root uptake
Can use kinetic-allometric approach with simple foodchains for terrestrial/riparian vertebrates
What is Allometry?
Size effects rates of all biological structures and processes from cellular metabolism to population dynamics
The dependence of a biological variable Y on a body mass M is typically characterised by an allometric scaling law of the form:
Y = aMb
where a and b are constants
b most often = ‘quartile values’:
metabolic rates scale as M0.75
M0.75 is often referred to as metabolic live-weight
life-span scales as M0.25 food, water and inhalation rates scale as M0.75
All potential useful for radioecological models, but:
What is Allometry?
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Allometric – radioecological parameters
For (some) radionuclides both the biological half-life (often M0.25) and transfer from diet (M-
0.75) have been found to scale allometrically RESRAD-BIOTA uses allometric relationships
for radionuclide biological half-lives and a number of other animal parameters (e.g. food & water intake, life-span, inhalation rate) for terrestrial and riparian vertebrates
Allometric calculations, e.g. Cs
kg/d
T1/2 =13.22*(mass0.237)
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Allometric calculations, e.g. Cs
kg/d
T1/2 =13.22*(mass0.237)
Ff=8.89*(mass-0.73)
Transfer coefficient Ff ( d kg-1) = Equilibrium activity concentration in animal (Bq kg-1 FW)
Daily intake of radionuclide (Bq d-1)
Allometric calculations, e.g. Cs
kg/d
T1/2 =13.22*(mass0.237)
Ff=8.89*(mass-0.73)
DMI=0.0551*(mass0.74)
Allometric calculations, e.g. Cs
kg/d
T1/2 =13.22*(mass0.237)
Ff=8.89*(mass-0.73)
DMI=0.0551*(mass0.74)
Allometric calculations, e.g. Cs
kg/d
T1/2 =13.22*(mass0.237)
Ff=8.89*(mass-0.73)
DMI=0.0551*(mass0.74)
Bq/kg = Ff x DMI
Transfer coefficient Ff ( d kg-1) = Equilibrium activity concentration in animal (Bq kg-1 FW)
Daily intake of radionuclide (Bq d-1)
Create an organism and foodchain
RESRAD-BIOTA Level 3 Soil activity concentrations are available:
Cs-137 1000 Bq/kg
Pu-239 550 Bq/kg Water concentration:
Cs-137 1 Bq/kg
Pu-239 1E-3 Bq/kg Alpha RBE=10; Cut-off half-life=180 Dormouse characteristics:
Size – 9x3x3 cm
Weight - 30 g
Occupancy – 50% in soil/50% on soil
RESRAD-BIOTA Level 3
Diet – 70 % seeds and 30 % invertebrates
Concentration ratios for dormouse dietSeed
Cs-137 0.7
Pu-239 5E-3
Invertebrate
Cs-137 0.13
Pu-239 0.1