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David Copplestone CEH Lancaster 1 st – 3 rd April 2014.

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Presentation on theme: "David Copplestone CEH Lancaster 1 st – 3 rd April 2014."— Presentation transcript:

1 David Copplestone CEH Lancaster 1 st – 3 rd April 2014

2  What’s the issue?  Obtaining air concentrations for noble gases  Estimating doses to wildlife from noble gases

3  Nuclear power plants  ~ 85% of the total activity released is in the form of noble gases (Ar-41, Kr-85)  Except for one model, none of the available tools estimate doses to wildlife from noble gases  Most analogue radionuclides that could be used will massively over predict the dose rate

4  Initially, during screening, used Cs-137 as analogue  Essentially any release containing Ar-41 or Kr-85 exceeded the screening value  Very conservative  Lead to refining of modelling approach

5  Various tools for atmospheric modelling (see Jordi’s presentation)  Essentially need to predict the air concentration at the point of interest (i.e. where biota are) following release  Simple models likely to be sufficient (dose rates are typically very small)  SRS-19 or R91 should be adequate

6  Need the distance to receptor  Release height  Wind speed  Time wind blows in the direction of the receptor  Duration of discharge  Buildings nearby?  Deposition coefficients (wet and dry)  Etc.

7  Noble gases have a small but finite solubility in water and body fluids  Dose contribution is negligible (CRs therefore set to 0)  Noble gases are not deposited to soil (so no plant uptake etc)  Will be exchange within the air pore volume of surface soil (but small component)  So assumes pore air concentration = ground level air concentration  Other factors as default in dose assessment tool (e.g. occupancy factors)

8  Initially produced back in 2001  Updated a couple of times  No further development work (superseded by ERICA Tool)  Freely available (documented) spreadsheet model for coastal, freshwater and terrestrial ecosystems  Limited radionuclide list and transfer parameter database

9 Ensure macros are enabled in Excel

10 Enter 1 Bq/m3 in each Ar-41, Kr-85

11 Press F1 to bring up the control panel

12

13  For similar reference organisms then it is possible to add the dose rate from Ar-41 and Kr-85 to the dose rates predicted by other tools (gives total dose rate)  Generally negligible dose rates but addresses perception issues and is more realistic than using analogues


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