WG8 Biota modelling: Further development of transfer and exposure - - PowerPoint PPT Presentation

MODARIA WG8 Biota modelling: Further development of transfer and exposure models and application to scenarios

Objectives

........ to improve Member States’ assessment capabilities for protection of the environment by comparing, improving and validating models being used or developed, for biota dose assessment as part of the regulatory process of licensing and compliance monitoring of authorised releases of radionuclides.

Why?

• Revised BSS –assessment of radiological

environmental impact

• Revised ICRP Recommendations & RAP

Framework developments

• Available models are relatively new and

being developed

• Various national initiatives

What did EMRAS I & II WG’s achieve?

• Demonstrated that the dosimetric components

(DCC) of commonly used models give generally comparable estimates of dose when assume homogenous distribution in organism and media.

• But not the transfer components – predictions of
• rganisms equilibrium activity concentrations

vary by orders of magnitude

Scenario applications

Perch Lake (Chalk River Canada)

• Models validated using

laboratory data performed relatively poorly

• Models using water

chemistry in transfer prediction performed relatively well

• Predictions for

mammals/heptofaua poor

Perch Lake (Chalk River Canada)

• Models validated using

laboratory data performed relatively poorly

• Models using water

chemistry in transfer prediction performed relatively well

• Predictions for

mammals/heptofaua poor

Chernobyl Exclusion Zone

• Orders of magnitude

variation in predicted

• rganism concentrations
• External dose predictions

reasonable (TLDs on small mammals)

• Importance of correct

parametersation of diet in foodchain models

Chernobyl Exclusion Zone

• Orders of magnitude

variation in predicted

• rganism concentrations
• External dose predictions

reasonable (TLDs on small mammals)

• Importance of correct

parametersation of diet in foodchain models

Little Forest Burial Ground

• How to address ‘unusual’

exposure scenarios (tree growing on waste trenches)

• Progeny assumptions

Beaverlodge Lake

• Progeny assumptions
• Data gaps
• Recommendations on

monitoring programmes (organisms and radionuclides)

• Heterogeneous media

distribution

• Uncertainty of Kd
• ‘Consensus approach’

‘Wetland’

• Perhaps surprisingly little

variation in organism activity concs (draft wildlife TRS available)

• Assumptions of diet source

(aquatic or terrestrial)

• External dose - correction (or

not) of soil moisture content

• First model-data comparison of

C-14 specific activity approaches for wildlife

1 10 100 1000 10000 100000

Trees Snakes Frogs Insects Peat moss Small plants Rodents

Erica (eriss/ARPANSA) Erica (ANSTO) Erica (CEH) Erica (SCK) RESRAD-Biota K-Biota Measured

‘Benefits’

• Realisation of need to compile transfer

parameters (CR) for wildlife (EMRAS II WG)

– used for draft IAEA TRS on wildlife CR values and ICRP-114

• Various model improvements/identification
• f limitations
• Training

MODARIA – potential activities

• Scenario applications

– those to date relatively simplistic – concentrated on model-data comparisons and not application to assessments – How integrate with human assessments

MODARIA – potential activities

• Training

– best practice guidance (linked to scenarios)

• Non-equilibrium conditions (EMRAS II review)

– Identify scenarios (source terms/radionuclides) where dynamic models may be required – Scenarios testing using existing models/adapt human assessment models (compare to equilibrium assumptions) – How interpret results?

MODARIA – potential activities

• ‘Dosimetry’

– Heterogeneous distribution in environment – Heterogeneous distribution in organism (other

• n-going activities?)

– Plant geometetries

Interactions with other WG

• Integration human-wildlife assessment
• Effects group (interpretation of dynamic

models, heterogeneous distribution activities)

• Developments for ‘Radioecology data’ WG

(inc. application of outputs) feedback limitations/scenario applications

• Scenario sharing (marine, legacy, routine

releases)