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Context The French Atomic Commission (CEA) is in charge of the - - PowerPoint PPT Presentation

Jan 13, 2023 281 likes •618 views

Presentation of the CERES platform C ode d' E valuations R apides E nvironnementales et S anitaires Harmo13, France, 2010 June 1 -4 CEA, DAM, DIF, F-91297 Arpajon CEDEX 1 Context The French Atomic Commission (CEA) is in charge of the

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CEA, DAM, DIF, F-91297 Arpajon CEDEX Harmo’13, France, 2010 June 1-4

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Presentation of the CERES platform

Code d' Evaluations Rapides Environnementales et Sanitaires

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CEA, DAM, DIF, F-91297 Arpajon CEDEX Harmo’13, France, 2010 June 1-4

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Context

  • The French Atomic Commission (CEA) is in charge of the

evaluation of the environmental and sanitary impact of radionuclides emitted in atmosphere or rivers by its installations

  • In this context, the CERES application (Code d'Evaluations

Rapides Environnementales et Sanitaires) has been developed

  • To manage Emergency situations
  • To realize Safety studies
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CEA, DAM, DIF, F-91297 Arpajon CEDEX Harmo’13, France, 2010 June 1-4

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Aim of the CERES platform

  • Two versions of the platform

Emergency Safety studies (more options) Initial menu Main interface, depending on initial choice

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CEA, DAM, DIF, F-91297 Arpajon CEDEX Harmo’13, France, 2010 June 1-4

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Main features

1. Realization of impact (chronic situations) and danger studies (accidental situations) of radionuclides releases:  accidental atmospheric releases  routine atmospheric releases  routine liquid releases in rivers 2. All kind of installations 3. Effective dose evaluation, taking into account all exposure pathways  short term exposure  long term exposure (after foodstuff transfer) 4. Visualization of atmospheric consequences as isolines curves on maps

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CEA, DAM, DIF, F-91297 Arpajon CEDEX Harmo’13, France, 2010 June 1-4

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Dose limits

Effective dose, all exposure pathways included, to be compared to:  Normal releases  Limit for the public: 1 mSv/year  Natural exposure in France: from 2 to 3 mSv/year  Accidental situation  2009/11/20 Decree for short term exposure 10 mSv for sheltering 50 mSv for evacuation

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CERES platform: Main calculation steps

  • Example for accidental situation
  • 1. Site selection

 From a list defined by administrator

  • 2. Source term definition or calculation
  • 3. Dispersion calculation

 Atmospheric activity concentrations and deposits per isotope, with daughtering and radioactive decay

  • 4. Consequences evaluation

 Short term: doses due to irradiation by the plume and deposition and doses due to inhalation  Food stuff transfer in vegetal and animals  Evaluation of doses due to ingestion and long term irradiation by deposits

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CEA, DAM, DIF, F-91297 Arpajon CEDEX Harmo’13, France, 2010 June 1-4

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Step 1/4: Site selection

Sites are characterized by population localization, measurements points, soils and agricultural production (vegetal and animals), human diets … used for long term exposure and results visualization on G.I.S

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CEA, DAM, DIF, F-91297 Arpajon CEDEX Harmo’13, France, 2010 June 1-4

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Example of site database

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CEA, DAM, DIF, F-91297 Arpajon CEDEX Harmo’13, France, 2010 June 1-4

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Step 2/4: Activity emitted in the environment

  • Different ways of definition of the “environmental” source

term

  • 1. Defined through the interface, from activity in the

installation, using multiplying coefficients  Initial activity in the plant defined in Bq or grams  Time dependant  About 600 isotopes

  • 3. Use of ERASTEM model

 Box model, using emission time dependant coefficients, filtration, decay…  Helps for evaluation of impact on workers

suite

  • 2. Use of formatted excel files

suite

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CEA, DAM, DIF, F-91297 Arpajon CEDEX Harmo’13, France, 2010 June 1-4

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Characteristics of isotopes

retour

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CEA, DAM, DIF, F-91297 Arpajon CEDEX Harmo’13, France, 2010 June 1-4

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Definition of activity emitted

  • Selection of radionuclides in a list
  • Use of Excel file

Clearance and deposition velocity proposed as default values

Possible change of release height Definition of release point or selection in a site specific list Release defined in mass or activity retour

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Step 3/4: Atmospheric dispersion model

  • Default option: Use of MITHRA code

 Gaussian puff model (Doury’s formulas or Pasquill’s)  Releases and meteorological conditions variable with time  Radioactive decay and daughtering  Depletion due to dry and wet deposition  Specific model for tritium  Default parameters for atmospheric dispersion: Doury’s parameters:  Function of travel time  Independent of site and roughness  Two stability classes, function of vertical temperature gradient

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CEA, DAM, DIF, F-91297 Arpajon CEDEX Harmo’13, France, 2010 June 1-4

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Atmospheric dispersion

 Effect of particle size on deposition > evaluation of deposition velocity function of the particle size and density (Florin’s formula)  Plume rise due to initial energy (fires, overpressure, ventilation rates …)  Possible use of outputs from other models (3D, local, mesoscale …)

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Input: Meteorological data

  • Accidental Situation: Met data varying with time – observation from

the site or forecasts - can use results from MEDICIS system

Default values Data used for Tritium dispersion 2 atmospheric stability classes Normal (DN) or Weak Diffusion (DF)

Wind meandering factor

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Step 4/4: Impact evaluation

  • Impact calculations are done for points and instants where

dispersion results are available

  • Breathing rates (moderated physic activity for short term

assessment) and site characteristics (soils, crops, diet… - for long term assessment) proposed as default values

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Results selection from user database

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Results files

  • Word format
  • Results compared to emergency levels defined in 2009-11-

20 decree

  • All hypothesis noted in the listing for quality (source term,

met data, dose coefficients, breathing rates, soil to vegetal transfer coefficients, vegetal to animal transfer coefficients…)

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Some graphic results

Contribution of pathways or of isotopes to the dose

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G.I.S

Link to Mapinfo Visualization of atmospheric dispersion and consequences as isolines on maps

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Assessment map

fin

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Chronic releases

  • Atmospheric releases : GASCON
  • Liquid releases : ABRICOT
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Routine Atmospheric releases

  • Dispersion evaluation (Bq/m3- air)

 air activity concentrations and depositions for reference groups,  Using site wind rose

Rose des vents toutes vitesses confondues en fonction des classes de diffusion 0% 2% 4% 6% 8% 10% 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340

Diffusion faible Diffusion normale Pluie vent du Nord vent du Sud

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GASCON code

  • Use of mean annual release
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Population group

  • Definition of reference groups, that can be characterized by 3

life places

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GASCON code

  • Diet habits: function of site
  • Breathing rates: mean daily value
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Some results

  • word and excel type
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  • Annual activity emitted in the environment

 Directly from plant  After purification  Sum of both

Routine liquid releases

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Abricot code

  • Transfer or retention in rivers or groundwater simulated
  • Liquid media characteristics proposed: site specific values
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Abricot code

  • Characteristics of reference groups

 Diet habits & breathing rates Lieu de vie  Soils  Vegetables and cattle  Irrigation

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Code Abricot

  • word and excel type
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Conclusion

  • By developing the CERES platform, CEA defined an application that

can be used for impact assessment studies for  Atmospheric and liquid releases  For accidental situations or chronic releases

  • This application :

 Can integrate new models for specific isotopes as example  Is user friendly with many values proposed as default options

  • All data are stored in databases for quality insurance
  • A version for toxic risk is under development
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Data used

  • Dose coefficients

 External irradiation Federal Guidance 12  Inhalation & ingestion  Effective : decree of 2003-09-01 (i.e. data from E.D. 96-29)  Organ (thyroïd) : ICRP 71 & 72

  • Breathing rates: ICRP 66
  • Transfer in foodstuff

 International recommanded data: IAEA, UIR, EEC, NRPB …