heterogeneous vs homogeneous distribution of radionuclides in sediment regarding dose rate calculation

Transcription

1 heterogeneous vs homogeneous distribution of radionuclides in sediment regarding dose rate calculation EMRAS II BMG Vienna January 2011 K. Beaugelin-Seiller

2 Summary of the previous episodes Context Sediments heterogeneously contaminated: impact on dose rates for wildlife? Available tools consider in general at the best a single layer homogeneously contaminated Exceptions: Doses3D and EDEN Possibility to consider at least 1 volume and 1 surface DCC for a same sediment Agreement between surface DCC never tested Definition of common scenarios for the tests Heterogeneous media January 2011 IAEA, Vienna 2/20

3 Summary of the previous episodes Results of comparisons 1 RN, 2 organisms, 3 locations, 2 DCC types 9 scenarios among which 4 about surface DCCs 1.00E E E-02 Th-234 surface DCC µgy/h per Bq/m² Big discrepancies identified at the first run for surface DCCs Bugs identified in EDEN 1.00E E E E E-07 EDEN 2009 Doses3D 1.00E E Heterogeneous media January 2011 IAEA, Vienna 3/20

4 Summary of the previous episodes Results of comparisons 1 RN, 2 organisms, 3 locations, 2 DCC types 9 scenarios among which 4 about surface DCCs 1.00E E E-02 Th-234 surface DCC µgy/h per Bq/m² Big discrepancies identified at the first run for surface DCCs Bugs identified in EDEN 1.00E E E E E-07 EDEN 2009 EDEN 2010 Doses3D A second run Better convergence but still some differences (organims at the interface ) 1.00E E Not possible to go deeper in the comparisons Heterogeneous media January 2011 IAEA, Vienna 4/20

5 Surface DCC calculation EDEN Validation E.D.E.N. 2.2 Elementary Dose Evaluation for Natural environment IRSN 2009 Heterogeneous media January 2011 IAEA, Vienna 5/20

6 Continuity between volume and surface exposure Principles Basic major mono-energetic DCCs MeV.g -1.s -1 Lagrande interpolation (more energies) For a given RN Linear interpolation on its spectrum Total DCC = sum of mono-energetic DCCs MeV.g -1.s -1 to convert into the appropriate unit Heterogeneous media January 2011 IAEA, Vienna 6/20

7 Continuity between volume and surface exposure EDEN internal consistency Alpha radiation V1 : 1 µm ; V2 : 1 mm ; S E : 2 to 10 MeV Orga nism Radiative media (surface or volume exposure) 1.4E E E E E E E-03 Energy deposit ((MeV/g)/(Bq.s)) Surface Volume 10-3 Volume E E (MeV) Good agreement + influence of the layer thickness Heterogeneous media January 2011 IAEA, Vienna 7/20

8 Continuity between volume and surface exposure EDEN internal consistency beta radiation V1 : 1 µm ; V2 : 1 mm ; S Two methods (statistical vs maps) Orga nism Radiative media (surface or volume exposure) Energy deposit ((MeV/g)/(Bq.s)) 2.5E E E E E-04 deposit map method Surface Volume 10-3 Volume E E (MeV) Good agreement + influence of the layer thickness Heterogeneous media January 2011 IAEA, Vienna 8/20

9 Continuity between volume and surface exposure EDEN internal consistency Orga nism Radiative media (surface or volume exposure) gamma radiation Three methodes implemented in EDEN Result retained : best convergence scheme among the three V : 1 mm ; S Energy deposit ((MeV/g)/(Bq.s)) 2.50E E E E-06 Surface Volume (10-3) 5.00E E E (MeV) Good agreement especially for high energy Heterogeneous media January 2011 IAEA, Vienna 9/20

10 Comparison EDEN vs MCNP«Universe» volume Beta radiation Organism Surface or volume source of exposure DCC ((Mev/g).cm 2 /(Bq.s)) 6.0E E E E E-02 MCNP EDEN 1.0E E E (MeV) Surface DCC Heterogeneous media January 2011 IAEA, Vienna 10/20

11 Comparison EDEN vs MCNP«Universe» volume Beta radiation DCC ((Mev/g).cm 2 /(Bq.s)) 6.0E E E E-02 DCC MCNP EDEN 2.0E-02 ((MeV/g)cm 3 /(Bq.s)) 1.0E E E E E (MeV) 4.0E E-06 Surface DCC 2.0E E-06 Organism Surface or volume source of exposure MCNP EDEN EDEN corrected 0.0E E (MeV) Good agreement Volume DCC Heterogeneous media January 2011 IAEA, Vienna 11/20

12 Comparison EDEN vs MCNP«Universe» volume Gamma radiation Organism Surface or volume source of exposure DCC ((MeV/g).cm 2 /(Bq.s)) 1.2E E E E-02 MCNP EDEN 4.0E E E E (MeV) Surface DCC Heterogeneous media January 2011 IAEA, Vienna 12/20

13 Comparison EDEN vs MCNP«Universe» volume Gamma radiation Organism Surface or volume source of exposure DCC ((MeV/g).cm 2 /(Bq.s)) 1.2E-01 DCC 1.0E-01 ((MeV/g).cm 3 /(Bq.s)) 1.2E E E E-02 MCNP EDEN 8.0E E E E E E E E (MeV) 0.0E+00 Surface DCC E (MeV) MCNP EDEN corrected EDEN Volume DCC Good agreement Heterogeneous media January 2011 IAEA, Vienna 13/20

14 Conclusions EDEN validation Surface exposure treatment consistent with continuity V->S DCC consistent with energy released X size of radiating source Beta radiation: good agreement EDEN results vs MCNP Gamma radiation: order of magnitude consistent (EDEN<MCNP) Confidence in EDEN results Heterogeneous media January 2011 IAEA, Vienna 14/20

15 Case study: U family in sediment Canadian lakes data Heterogeneous media January 2011 IAEA, Vienna 15/20

16 depth (cm) depth (cm) An heterogeneous contamination of sediment Beaver Lodge Ace Bay Dubyna Lake Deep Th-234 U-238 activity (Bq/kg) Th-234 U-238 activity (Bq/kg) 0.00E E E E E E E E E E E E E E E E Heterogeneous media January 2011 IAEA, Vienna 16/20

17 depth (cm) The proposed approach (1/2) Beaver Lodge Ace Bay Measured values Usual modelling Alternative modelling U-238 in sediment (Bq/kg ww) Heterogeneous media January 2011 IAEA, Vienna 17/20

18 depth (cm) The proposed approach (2/2) Dubyna Lake Deep Measured values Usual modelling Alternative modelling U-238 in sediment (Bq/kg ww) 0.00E E E E E E E E E E E Heterogeneous media January 2011 IAEA, Vienna 18/20

19 Exposure scene Layer 1 Layer 2 Insect larvae Benthic fish Heterogeneous media January 2011 IAEA, Vienna 19/20

20 dose rate (µgy/h) dose rate (µgy/h) Total dose rates received Beaver Lodge Ace Bay Dubyna Lake Deep comparison between an homogeneous and an heterogeneous contamination of sediments comparison between an homogeneous and an heterogeneous contamination of sediments 1.00E+01 insect fish 1.00E+03 insect fish 1.00E E E-01 heterogeneous distribution homgeneous distribution 1.00E E+00 heterogeneous distribution homgeneous distribution 1.00E E E E-02 on the sediment 4 cm under the surface 15 cm under the surface on the sediment on the sediment 1 cm under the surface 4 cm under the surface on the sediment exposure scenario exposure scenario Heterogeneous media January 2011 IAEA, Vienna 20/20

21 RNs contribution/ insect larvae (1/2) Beaver Lodge Ace Bay Heterogeneous distribution Homogeneous distribution BL insect larvae under a 4 cm layer of sediment U238 Th234 Pa234m U234 Th230 Ra226 Pb210 Po210 BL insect larvae under a 15 cm layer of sediment Heterogeneous media January 2011 IAEA, Vienna 21/20

22 RNs contribution/ insect larvae (2/2) Dubyna Lake Deep Heterogeneous distribution Homogeneous distribution DLD insect larvae under a 1 cm layer of sediment U238 Th234 Pa234m U234 Th230 Ra226 Pb210 Po210 DLD insect larvae under a 4 cm layer of sediment Heterogeneous media January 2011 IAEA, Vienna 22/20

23 RNs contribution/ fish Beaver Lodge Ace Bay Heterogeneous distribution Homogeneous distribution Dubyna Lake Deep U238 Th234 Pa234m U234 Th230 Ra226 Pb210 Po210 Heterogeneous media January 2011 IAEA, Vienna 23/20