Nick Beresford (CEH) & David Copplestone (Stirling Univ.)

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

www.ceh.ac.uk/PROTECT

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.


RESRAD-BIOTA v’s ERICATerms used

Tiers are Levels CRs are Bivs EMCLs are BCGs (Biota Concentration

Guides) DCCs are DCFs (Dose Conversion Factor)


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)


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


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


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?



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)



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)


kg/d

T1/2 =13.22*(mass0.237)

Ff=8.89*(mass-0.73)

DMI=0.0551*(mass0.74)


kg/d

T1/2 =13.22*(mass0.237)

Ff=8.89*(mass-0.73)

DMI=0.0551*(mass0.74)


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

Documents

Nick Beresford (CEH) & David Copplestone (Stirling Univ.)