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RESRAD-BIOTA

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

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RESRAD-BIOTA

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  1. Nick Beresford (CEH) & David Copplestone (Stirling Univ.) RESRAD-BIOTA

  2. 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

  3. Availability and documentation • Available at no cost for download on-line • Comparatively well documented • Being maintained and upgraded • Training available

  4. RESRAD-BIOTA www.ead.anl.gov/resrad/home2/

  5. USDOE Graded Approach Series of paper in: Woodhead, D.S. (Ed.), 2003. Protection of the environment from ionising radiation. Journal of Environmental Radioactivity, 66. BDAC

  6. RESRAD-BIOTAv’sERICATerms used • Tiers are Levels • CRs are Bivs • EMCLs are BCGs (Biota Concentration Guides) • DCCs are DCFs (Dose Conversion Factor) www.ceh.ac.uk/PROTECT

  7. RESRAD-BIOTA Level www.ceh.ac.uk/PROTECT

  8. USDOE - benchmarks Based 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

  9. RESRAD-BIOTA - BCGs Estimated 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

  10. LEVEL 1

  11. 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)

  12. 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 www.ceh.ac.uk/PROTECT

  13. www.ceh.ac.uk/PROTECT

  14. Level 2

  15. Level 2 • Site specific CR values available for aquatic animal: • Co 1500; Cs 9000; H 0.25; Pu 200 www.ceh.ac.uk/PROTECT

  16. Level 3

  17. RESRAD-BIOTA • Also uses CRs (or Bivs), but:

  18. RESRAD-BIOTA • Can use kinetic-allometric approach with simple foodchains for terrestrial/riparian vertebrates Root uptake Vegetation Soil contamination Soil invertebrate Herbivorous mammals Carnivorous mammals Fugitive dust Herbivorous birds Water contamination

  19. 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

  20. What is Allometry? • 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: www.ceh.ac.uk/PROTECT

  21. 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 www.ceh.ac.uk/PROTECT

  22. Allometric calculations, e.g. Cs kg/d T1/2 =13.22*(mass0.237) www.ceh.ac.uk/PROTECT

  23. Allometric calculations, e.g. Cs Transfer coefficient Ff( d kg-1) = Equilibrium activity concentration in animal (Bqkg-1 FW) Daily intake of radionuclide (Bq d-1) kg/d T1/2 =13.22*(mass0.237) Ff=8.89*(mass-0.73)

  24. Allometric calculations, e.g. Cs kg/d T1/2 =13.22*(mass0.237) Ff=8.89*(mass-0.73) DMI=0.0551*(mass0.74)

  25. Allometric calculations, e.g. Cs kg/d T1/2 =13.22*(mass0.237) Ff=8.89*(mass-0.73) DMI=0.0551*(mass0.74)

  26. Allometric calculations, e.g. Cs Transfer coefficient Ff( d kg-1) = Equilibrium activity concentration in animal (Bqkg-1 FW) Daily intake of radionuclide (Bq d-1) kg/d T1/2 =13.22*(mass0.237) Bq/kg = Ff x DMI Ff=8.89*(mass-0.73) DMI=0.0551*(mass0.74)

  27. Create an organism and foodchain

  28. 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

  29. RESRAD-BIOTA Level 3 Diet – 70 % seeds and 30 % invertebrates Concentration ratios for dormouse diet Seed Cs-137 0.7 Pu-239 5E-3 Invertebrate Cs-137 0.13 Pu-239 0.1

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