IAEA International Atomic Energy Agency Second Technical Meeting - - PowerPoint PPT Presentation

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IAEA International Atomic Energy Agency Second Technical Meeting - - PowerPoint PPT Presentation

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IAEA International Atomic Energy Agency Second Technical Meeting (TM) on the Environmental Modelling for Radiation Safety (EMRAS II) Intercomparison and Harmonization Project EMRAS II - Biota Modelling Group (WG4) Estimating radionuclide

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EMRAS II - Biota Modelling Group (WG4)

Estimating radionuclide activity concentrations in

  • rganisms, by using the ERICA Tool

NATIONAL CENTRE FOR SCIENTIFIC RESEARCH “DEMOKRITOS” Institute of Nuclear Technology - Radiation Protection Environmental Radioactivity Laboratory

Katerina D. Maroudi

Second Technical Meeting (TM) on the Environmental Modelling for Radiation Safety (EMRAS II) Intercomparison and Harmonization Project

IAEA

International Atomic Energy Agency

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CONTENTS

  • 1. Introduction
  • 2. The ERICA Tool
  • 3. Case Study
  • 4. Probabilistic Assessment
  • 5. Radiological Risk Assessment
  • 6. Remarks
  • 7. Conclusions - Perspectives

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CONTENTS

  • 1. Introduction
  • 2. The ERICA Tool
  • 3. Case Study
  • 4. Probabilistic Assessment
  • 5. Radiological Risk Assessment
  • 6. Remarks
  • 7. Conclusions - Perspectives

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OBJECTIVES

  • Exercise

Investigate the cause of communities and population level effects observed in Beaverlodge Lake and bays of Lake Athabasca. – Phase 1 Estimate radionuclide activity concentrations in specific

  • rganisms, living in contaminated areas.

Presentation Estimate radionuclide activity concentrations in these organisms, by using the ERICA Tool. Conduct an initial radiological assessment

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DEFINITIONS

  • Absorbed Dose (eV/gr) or (Gy)

the energy deposited in unit mass of absorbing material by ionizing radiation

  • Dose Rate (Gy/time unit)

the absorbed dose received over a unit of time

  • Activity Concentration (Bq/kg) or (Bq/l)

the activity of a specific radionuclide per unit mass or volume of matter

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CONTENTS

  • 1. Introduction
  • 2. The ERICA Tool
  • 3. Case Study
  • 4. Probabilistic Assessment
  • 5. Radiological Risk Assessment
  • 6. Remarks
  • 7. Conclusions - Perspectives

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ERICA Assessment Tool

Environmental Risk from Ionizing Contaminants: Assessment and management

  • ERICA Assessment Tool 1.0 May 2009
  • 15 Institutions / 7 European Countries 2004-2007
  • Supporting software program - facilitates the ERICA

Integrated Approach

  • Freshwater, terrestrial and marine ecosystems
  • 38 reference organisms
  • 63 radionuclides of 31 elements
  • Addition radionuclides and organisms
  • Probabilistic ability
  • Linked to on-line radiation effects [FREDERICA]

database

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ERICA Assessment Tool

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[Larsson, 2008]

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ASSESSMENT STRUCTURE

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Distribution function Distribution function

Isotopes Ecosystem Organisms Isotopes Ecosystem Organisms

Media Activity Concentrations and/or Activity Concentrations in Organisms Media Activity Concentrations and/or Activity Concentrations in Organisms Dose Rate Screening Values Distribution Coefficients Concentration Ratios Occupancy factors Radiation Weighting Factors Dose Rate Screening Values Distribution Coefficients Concentration Ratios Occupancy factors Radiation Weighting Factors Risk Quotients Dose Rate Activity Concentrations in Organisms/Media Risk Quotients Dose Rate Activity Concentrations in Organisms/Media

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CONTENTS

  • 1. Introduction
  • 2. The ERICA Tool
  • 3. Case Study
  • 4. Probabilistic Assessment
  • 5. Radiological Risk Assessment
  • 6. Remarks
  • 7. Conclusions - Perspectives

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CASE STUDY- ECOSYSTEM

Freshwater Ecosystem

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CASE STUDY- LOCATION

Beaverlodge Lake

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Lake Athabasca 16 Sites

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CASE STUDY- ORGANISMS

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Chironomus Riparius

Pisidium sp. Lake Whitefish White Sucker

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CASE STUDY- CONTAMINATION

  • Metals
  • Radionuclides

– 210Pb – 210Po – 226Ra – 230Th – 238U

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CONTENTS

  • 1. Introduction
  • 2. The ERICA Tool
  • 3. Case Study
  • 4. Probabilistic Assessment
  • 5. Radiological Risk Assessment
  • 6. Remarks
  • 7. Conclusions - Perspectives

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PROBABILISTIC ASSESSMENT

Assessment where probability distributions are assigned to model parameters and a probability distribution of the assessment endpoint is obtained by performing Monte Carlo simulations.

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TIER 3

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ASSESSMENT DETAILS

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  • Assessment details
  • Stakeholder

involvement

  • Problem formulation
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ASSESSMENT CONTEXT

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ADD ORGANISM (1)

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ADD ORGANISM (2)

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ADD ORGANISM (3)

Name Chironomus Riparius Pisidium sp. Lake Whitefish [Coregonus clupeaformis] White Sucker [Catostomus commersoni] Wildlife Group Aquatic Invertebrate Mollusc Fish Fish Comments Freshwater benthic invertebrate Freshwater fingernail clam (pea clam)

  • Bottom

feeding freshwater fish

  • Salmon family
  • Eat

cruastacens, snails, insects, etc

  • Bottom

feeding freshwater fish

  • Eat small

invertebrates and plant matter

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ADD ORGANISM (4)

Chironomus Riparius Pisidium sp. Lake Whitefish White Sucker Geometry (m) Length 3.4E-04 5.0E-03 4.36E-01 4.5E-01 Width 1.7E-04 1.5E-03 1.4E-02 1.5E-02 Depth 1.5E-04 1.0E-03 1.0E-02 1.0E-02 Mass (kg) ~1.6E-07 ~1.25E-06 1.362 1.191 Occupancy factors Water-Surface 0.0 0.0 0.0 0.0 Water 0.0 0.0 0.1 0.1 Sediment- Surface 0.1 0.9 0.9 0.9 Sediment 0.9 0.1 0.0 0.0

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ASSESSMENT CONTEXT

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RADIOECOLOGY PARAMETERS (1)

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  • 1. Concentration Ratio (CR)

) / / . . . .

1 3 1 1 − − − −

⋅ ⋅ ⋅ ⋅ = l Bq m Bq w d kg a (Bq

  • n in medi
  • ncentrati

Activity c ) w f kg dy (Bq a whole bo

  • n in biot
  • ncentrati

Activity c CR

  • 2. Distribution Coefficient (Kd), for aquatic

ecosystem

) . . dim

1 1 − −

⋅ ⋅ = l r (Bq

  • n in wate
  • ncentrati

Activity c ) w d kg ent (Bq

  • n in se
  • ncentrati

Activity c Kd

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RADIOECOLOGY PARAMETERS (2)

Incomplete data for the Concentration Ratio (CR)

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RADIOECOLOGY PARAMETERS (3)

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INPUTS (1)

At least one concentration for each radionuclide must be given, but not all cells have to be filled in.

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INPUTS (2)

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OUTPUTS (1)

Deterministic Values: for deterministic inputs only

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OUTPUTS (2)

Probabilistic Data: for probability distributions

Variance Deviation Standard =

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CONTENTS

  • 1. Introduction
  • 2. The ERICA Tool
  • 3. Case Study
  • 4. Probabilistic Assessment
  • 5. Radiological Risk Assessment
  • 6. Remarks
  • 7. Conclusions - Perspectives

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RADIOLOGICAL RISK ASSESSMENT

A qualitative or quantitative evaluation of the risk posed to human health and/or the environment by the actual and/or potential presence of pollutants.

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TIER 1 - TIER 2

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RISK QUOTIENT

  • A measure of the risk caused by each

contaminant to an organism.

  • For radioactive substances:

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Limit ion Concentrat Media tal Environmen ion Concentrat Activity Media Quotient Risk _ _ _ _ _ _ =

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ASSESSMENT DETAILS

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  • Assessment details
  • Stakeholder

involvement

  • Problem formulation
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ASSESSMENT CONTEXT

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INPUTS

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OUTPUTS

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CONTENTS

  • 1. Introduction
  • 2. The ERICA Tool
  • 3. Case Study
  • 4. Probabilistic Assessment
  • 5. Radiological Risk Assessment
  • 6. Remarks
  • 7. Conclusions - Perspectives

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REMARKS (1)

  • 1. Parameters defined by the ERICA Tool:

– Dose Rate Screening Value – Environmental Media Concentration Limits – Distribution Coefficients (Kd) (per radionuclide) – Concentration Ratios (CR’s) (per radionuclide

and organism)

– Radiation Weighting Factors

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REMARKS (2)

  • 2. Creation of new organisms:

– Occupancy factors chosen arbitrarily – CR values missing – “Chironomus Riparius” and “Pisidium sp.” mass range – “Chironomus Riparius” mass range under the minimum value – Organism density assumed 1g/cm3

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REMARKS (3)

  • 3. Percentage dry weight sediment or soil value:

enables a conversion to fresh weight activity concentrations.

– Biota and water activity concentrations (via CRs and Kds) soil and sediment activity concentrations on a dry weight basis – External dose rates fresh weight activity concentrations.

  • The assumption of 100% leads

to conservative dose rates.

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CONTENTS

  • 1. Introduction
  • 2. The ERICA Tool
  • 3. Case Study
  • 4. Probabilistic Assessment
  • 5. Radiological Risk Assessment
  • 6. Remarks
  • 7. Conclusions - Perspectives

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CONCLUSIONS

Fast and easy to use Assumptions Results dependence on parameters choice Results uncertainty Results verification

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  • Consider all exposure pathways in a more

realistic approach

  • Take into account trophic relationships

between species (Food chain)

  • Study transfer parameters
  • Consider biological and ecological half-lives
  • Estimate effective dose equivalent
  • Embody human into the Tool

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PERSPECTIVES (1)

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PERSPECTIVES (2)

  • Input organism and media composition and

mass density

  • Input radionuclide distribution in media and
  • rganism
  • Create complex geometries - phantoms
  • Provide an ERICA Tool verification
  • Make a comparison of different Tiers results

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Thank you for your attention!

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