Dose Modeling Comparison for Terrestrial Biota: IAEA EMRAS II Biota - PowerPoint PPT Presentation

Dose Modeling Comparison for Terrestrial Biota: IAEA EMRAS II Biota Working Group's Little Forest Burial Ground Scenario MP Johansen 1 , CL Barnett 2 , NA Beresford 2 , JE Brown 3 , M Č erne 4 , BJ Howard 2 , S Kamboj 5 , D-K Keum 6 , B Smodiš 4 , JR Twining 1 , H Vandenhove 7 , J Vives i Batlle 7 , MD Wood 8 , and C Yu 5 1 Australian Nuclear Science and Technology Organisation, NSW, AU 2 Centre for Ecology & Hydrology, Lancaster, UK 3 Norwegian Radiation Protection Authority, Oesteraas, NO 4 Jožef Stefan Institute, Ljubljana, SI 5 Argonne National Laboratory, Illinois, US 6 Korea Atomic Energy Research Institute, Daejeon, KR 7 Belgian Nuclear Research Centre, Mol, BE 8 Manchester Metropolitan Univ., Manchester, UK

Motivated by: • Increased attention on biota dose assessment (e.g., Handbook of Wildlife Transfer, Wildlife transfer database, recent/emerging ICRP docs) • Ongoing development of biota dose codes (e.g., increased probabilistic capabilities) • Recommendations of Chernobyl and Perch Lake model inter-comparison studies. • Examine causes of variability

Little Forest Burial Ground near Sydney Australia 1960-68 Disposal Today- Trace levels of 60 Co, 90 Sr, 137 Cs, 232 Th, 234 U, 238 U, 238 Pu, 39/240 Pu, 241 Am.

Ten representative Plant – Grass ( Poaceae) organisms Plant, tree – Acacia ( Acacia longifolia) Plant, tuber – Pencil Yam ( Vigna lanceolata ) Annelid – Earthworm ( Lumbricidae ) Arthropods – Grasshopper ( Caelifera ) Reptile – goanna ( Varanus varius ) Bird – Australian raven ( Corvus coronides ) Mammal, monotreme – Echidna ( Tachyglossus ) Mammal, placental canine – Fox ( Vulpes vulpes ) Mammal, marsupial – Wallaby ( Wallabia bicolour )

Ranges of: Ten representative Plant – Grass ( Poaceae) organisms Sizes & shapes Plant, tree – Acacia ( Acacia longifolia) Plant, tuber – Pencil Yam ( Vigna lanceolata ) Annelid – Earthworm ( Lumbricidae ) Exposure Configurations: Arthropods – Grasshopper ( Caelifera ) Reptile – goanna ( Varanus varius ) Bird – Australian raven ( Corvus coronides ) Mammal, monotreme – Echidna ( Tachyglossus ) Mammal, placental canine – Fox ( Vulpes vulpes ) Uptake & assimilation Mammal, marsupial – Wallaby ( Wallabia bicolour )

CRs Participants, codes, and approaches biokinetic allometric Participant Code Method for soil-to-organism transfer Centre for Ecology & Hydrology, ERICA Tool CR wo-soil (Wildlife Transfer Database) Lancaster, UK (tier 3) (ERICA-CEH) Belgian Nuclear Research Centre, ERICA Tool CR wo-soil (ERICA Tool defaults and IAEA reference docs) Mol, Belgium (tier 3) (ERICA-SCK) Jožef Stefan Institute, ERICA Tool CR wo-soil (ERICA Tool defaults) Ljubljana, Slovenia (tier 3) (ERICA-JSI) Norwegian Radiation Prot. Authority FASTer-lite used with Biokinetic transfer (compartment) models (parameters from reference Oesteraas, Norway ERICA Tool, Eikos, and docs; soil-to-diet CR values from ERICA-Tool defaults). (FASTer-lite-NRPA) ECOLOGO Korea Atomic Energy Res. Institute K-Biota CR wo-soil (ERICA Tool defaults for grass, tree, earthworm, insect, bird; Daejeon, Republic of Korea IAEA TRS 364 for yam (K-Biota-KAERI) Allometric equation (goanna, echidna, fox, and wallaby -USDOE and other reference docs) Argonne National Laboratory, RESRAD-BIOTA CR wo-soil (RESRAD-BIOTA defaults). Illinois, USA (RESRAD-BIOTA-ANL) Manchester Metropolitan University RESRAD-BIOTA CR wo-soil (RESRAD-BIOTA defaults for grass, tree, earthworm, insect) Manchester, UK (RESRAD-BIOTA-MMU) Allometric equation (goanna, raven, echidna, fox, and wallaby USDOE and other reference docs)

Example results: wallaby - acacia- 1.E+02 1.E+02 C o n c e n t ra t io n ra t io C o n c e n tra tio n ra tio 1.E+01 1.E+01 1.E+00 1.E+00 1.E-01 1.E-01 1.E-02 1.E-02 1.E-03 1.E-03 1.E-04 1.E-04 1.E-05 1.E-05 60 Co 90 Sr 137 Cs 232 Th 234 U 238 U 238 Pu 239/240 Pu 241 Am 60 Co 90 Sr 137 Cs 232 Th 234 U 238 U 238 Pu 239/240 Pu 241 Am Variation in transfer (concentration ratios) ERICA - CEH ERICA - SCK ERICA - JSI FASTER-lite - NRPA K-BIOTA - KAERI RESRAD-BIOTA - ANL RESRAD- BIOTA-MMU

Example results: wallaby - acacia- 1.E+02 1.E+02 C o n c e n t ra t io n ra t io C o n c e n tra tio n ra tio 1.E+01 1.E+01 1.E+00 1.E+00 1.E-01 1.E-01 1.E-02 1.E-02 1.E-03 1.E-03 1.E-04 1.E-04 1.E-05 1.E-05 60 Co 90 Sr 137 Cs 232 Th 234 U 238 U 238 Pu 239/240 Pu 241 Am 60 Co 90 Sr 137 Cs 232 Th 234 U 238 U 238 Pu 239/240 Pu 241 Am 1.E-03 1.E-03 1.E-04 1.E-04 Variation in transfer 1.E-05 1.E-05 (concentration ratios) 1.E-06 1.E-06 1.E-07 1.E-07 G y / day G y / d a y 1.E-08 1.E-08 1.E-09 1.E-09 1.E-10 1.E-10 1.E-11 1.E-11 1.E-12 1.E-12 1.E-13 1.E-13 ERICA - CEH ERICA - SCK ERICA - JSI FASTER-lite - NRPA 1.E-14 K-BIOTA - KAERI RESRAD-BIOTA - ANL RESRAD- BIOTA-MMU

Total dose v. CRs, considering α , β , γ Fig. 2. Predicted tissue concentrations (Bq/g) and total dose rates (Gy/d) vs. CR wo-soil for (a) Yam and (b) wallaby. Values have been normalized relative to soil concentrations of 1 Bq kg -1 . Fig. 2b Yam Fig. 2a Wallaby Total Doses (Gy/d), Tissue Concentrations (Bq/g) 1.00E-03 1.00E-03 Th-232 Co-60 1.00E-04 1.00E-04 U-238 Sr-90 Pu-239 1.00E-05 1.00E-05 Th- 232 Am-241 Tissue concentrations (Bq/g) 1.00E-06 1.00E-06 Total dose rates (Gy/d) Co-60 R 2 = 0.12 1.00E-07 1.00E-07 Th-232 progeny included 1.00E-08 1.00E-08 Th-232 progeny included 1.00E-09 1.00E-09 Th-232 R 2 = 0.72 1.00E-10 U-238 R 2 = 0.99 1.00E-10 Sr-90 Pu-239 R 2 = 0.56 Th-232 R 2 = 0.76 R 2 = 0.96 Am-241 R 2 = 0.88 1.00E-11 1.00E-11 1.00E-12 1.00E-12 0.00001 0.0001 0.001 0.01 0.1 1 0.00001 0.0001 0.001 0.01 0.1 1 CR wo-soil CR wo-soil

Conclusions: Orders-of-magnitude variation in total dose rate predictions among approaches due to: 4 Variation in total dose rates by attributed source (Orders of magnitude) 3 2 1 0 Transfer Exp. Config. Progeny Dose Param.

Conclusions: • Probabilistic functions allowed 95 th & 5 th envelope of predicted dose rates. 1.E-03 DCRL range for mammals, tree, bird screening value (Protect 2009) Max Tot dose rate (Gy/d) 1.E-04 1.E-05 1.E-06 1.E-07 grass acacia p. yam eworm grass goanna raven echidna fox wallaby hopper

Conclusions: • Provides useful feedback to model users and model developers:  Transfer Careful/considered use of ref values. Continued need to better understand & parameterize fundamental transfer mechanisms.  Exposure configurations Some configurations (tree roots accessing waste) were not easily modeled  Progeny Need to consider appropriate progeny cutoff periods relative to site waste emplacement and ecosystem persistence  Dose parameters (rad weighting factors, DCCs) <1 Order of magnitude variability is consistent with previous studies.

mathew.johansen@ansto.gov.au Comments: Thank you

Summary statistics measuring variation across all radionuclides Soil-to- Whole- organism organism Internal External transfer Tissue dose dose Total dose (CR wo-soil) Concentration Rates rates rates grass 0.44 0.44 0.65 0.38 0.61 acacia 0.16 0.41 0.66 0.47 0.57 pencil yam 0.59 0.60 0.67 0.43 0.64 earthworm 0.15 0.16 0.49 0.33 0.47 grasshopper 0.27 0.28 0.54 0.38 0.49 goanna 0.65 0.64 0.64 0.40 0.60 raven 0.34 0.57 0.64 0.47 0.61 echidna 0.58 0.44 0.65 0.38 0.61 fox 0.58 0.44 0.65 0.38 0.61 wallaby 0.58 0.44 0.65 0.38 0.61