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 Johansen1, CL Barnett2, NA Beresford2, JE Brown3, M Černe4, BJ Howard2, S Kamboj5, D-K Keum6, B Smodiš4, JR Twining1, H Vandenhove7, J Vives i Batlle7, MD Wood8, and C Yu5

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

Today- 1960-68 Disposal

Trace levels of 60Co, 90Sr, 137Cs, 232Th, 234U, 238U,

238Pu, 39/240Pu, 241Am.

Plant – Grass (Poaceae) 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)

Ten representative

• rganisms

Plant – Grass (Poaceae) 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)

Ten representative

• rganisms

Ranges of:

Sizes & shapes Exposure Configurations: Uptake & assimilation

Participants, codes, and approaches

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

• ther reference docs)

Argonne National Laboratory, Illinois, USA (RESRAD-BIOTA-ANL) RESRAD-BIOTA CRwo-soil (RESRAD-BIOTA defaults). Manchester Metropolitan University Manchester, UK (RESRAD-BIOTA-MMU) RESRAD-BIOTA CRwo-soil (RESRAD-BIOTA defaults for grass, tree, earthworm, insect) Allometric equation (goanna, raven, echidna, fox, and wallaby USDOE and other reference docs)

CRs biokinetic allometric

wallaby -

60Co 90Sr 137Cs 232 Th 234U 238U 238Pu 239/240Pu 241Am

Variation in transfer (concentration ratios)

ERICA - CEH ERICA - SCK ERICA - JSI FASTER-lite - NRPA K-BIOTA - KAERI RESRAD-BIOTA - ANL RESRAD- BIOTA-MMU

acacia-

60Co 90Sr 137Cs 232 Th 234U 238U 238Pu 239/240Pu 241Am

Example results:

1.E-05 1.E-04 1.E-03 1.E-02 1.E-01 1.E+00 1.E+01 1.E+02

C o n c e n tra tio n ra tio

1.E-05 1.E-04 1.E-03 1.E-02 1.E-01 1.E+00 1.E+01 1.E+02

C o n c e n t ra t io n ra t io

wallaby -

60Co 90Sr 137Cs 232 Th 234U 238U 238Pu 239/240Pu 241Am

Variation in transfer (concentration ratios)

1.E-14 1.E-13 1.E-12 1.E-11 1.E-10 1.E-09 1.E-08 1.E-07 1.E-06 1.E-05 1.E-04 1.E-03

G y / d a y

1.E-13 1.E-12 1.E-11 1.E-10 1.E-09 1.E-08 1.E-07 1.E-06 1.E-05 1.E-04 1.E-03

G y / day

ERICA - CEH ERICA - SCK ERICA - JSI FASTER-lite - NRPA K-BIOTA - KAERI RESRAD-BIOTA - ANL RESRAD- BIOTA-MMU

acacia-

60Co 90Sr 137Cs 232 Th 234U 238U 238Pu 239/240Pu 241Am

Example results:

1.E-05 1.E-04 1.E-03 1.E-02 1.E-01 1.E+00 1.E+01 1.E+02

C o n c e n tra tio n ra tio

1.E-05 1.E-04 1.E-03 1.E-02 1.E-01 1.E+00 1.E+01 1.E+02

C o n c e n t ra t io n ra t io

• Fig. 2. Predicted tissue concentrations (Bq/g) and total dose rates (Gy/d) vs. CRwo-soil for (a) Yam and (b) wallaby.

Values have been normalized relative to soil concentrations of 1 Bq kg-1.

1.00E-12 1.00E-11 1.00E-10 1.00E-09 1.00E-08 1.00E-07 1.00E-06 1.00E-05 1.00E-04 1.00E-03 0.00001 0.0001 0.001 0.01 0.1 1

Th-232 U-238 Pu-239 Am-241

1.00E-12 1.00E-11 1.00E-10 1.00E-09 1.00E-08 1.00E-07 1.00E-06 1.00E-05 1.00E-04 1.00E-03 0.00001 0.0001 0.001 0.01 0.1 1 Tissue concentrations (Bq/g) Total dose rates (Gy/d)

Co-60 Sr-90 Th- 232

Sr-90 R2= 0.96 Co-60 R2= 0.12

Th-232 R2= 0.76 Th-232 progeny included

CRwo-soil

• Fig. 2b Yam

Th-232 R2= 0.72 U-238 R2= 0.99 Pu-239 R2= 0.56 Am-241 R2= 0.88

• Fig. 2a Wallaby

Th-232 progeny included

CRwo-soil

Total dose v. CRs, considering α,β,γ

Total Doses (Gy/d), Tissue Concentrations (Bq/g)

1 2 3 4

Transfer

• Exp. Config.

Progeny Dose Param. (Orders of magnitude)

Conclusions:

Orders-of-magnitude variation in total dose rate predictions among approaches due to:

Variation in total dose rates by attributed source

Conclusions:

• Probabilistic functions allowed 95th & 5th envelope of

predicted dose rates.

1.E-07 1.E-06 1.E-05 1.E-04 1.E-03 grass acacia p. yam eworm grass hopper goanna raven echidna fox wallaby Max Tot dose rate (Gy/d)

screening value (Protect 2009) DCRL range for mammals, tree, bird

• 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.

Conclusions:

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

Summary statistics measuring variation across all radionuclides

Soil-to-

• rganism

transfer (CRwo-soil) Whole-

• rganism

Tissue Concentration Internal dose rates External dose rates Total dose 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