Terrestrial Assessment

1. Terrestrial Assessment Comparison of human and non human dose assessments for prospective new nuclear power stations

2. Outline • Background • Human assessment (assumptions) • Non-human assessment (assumptions) • Comparison of the results from the two assessments • Discussion of results? • Summary/Issues for PROTECT

3. Background

4. Background • Assessment loosely based on proposed build of new nuclear power stations (AGR and PWR types) • Terrestrial assessment looking at exposure to • humans via foodstuff/living nearby • Non-human species living in a (protected) Natura 2000 site at approximately the same distance as that for humans • Uses probable permitted discharge limits as input • Single source of radioactivity to assessment assumed

5. Map of proposed facility Agricultural land used for food crops/milk production 500m from aerial discharge Humans living at 100m from site Facility with sea discharge Terrestrial Natura 2000 site 500m from aerial discharge

6. Permitted discharge limits In TBq per year

7. Human assessment

8. Approach • Modelled using the Environment Agency Initial Radiological Assessment Tool • Prospective assessment • Simple spreadsheet tool

9. Assumptions • Assumes a ground level release & uniform windrose • Exposure to humans is at 100m from discharge point; assumed to be consuming high levels of locally sourced foods such as milk, beef, lamb, offal, green vegetables, root vegetables and fruit (sourced 500m from discharge point) • Other beta modelled as I-131 • Noble gases modelled as C-14 (not available in ERICA) • No direct shine assessment included (can’t do it for non-human species yet)

14. Non-human assessment

15. Assumptions • Modelled terrestrial input concentrations through IAEA SRS19 transfer model • Assumed ground level release • Distance to receptor = 500m • Used ERICA tool Tier 2, assuming reference organisms in the assessment and using all default concentration ratios, occupancy factors, etc for terrestrial environment • Other beta modelled as I-131 • Noble gases modelled as C-14

16. AGR - Screened against 10 µGy/h

17. PWR - Screened against 10 µGy/h

18. Results comparison

19. Predicted dose rates - human

20. Predicted dose rates - human

21. Non- human results – total doses µGy/h

22. Non- human results – total doses µGy/h

23. Non- human results – total doses µGy/h C-14 is the main contributor

24. Risk Quotients • Human results compared to 1mSv/y • Biota results compared to 10 and 40 µGy/h • (EA uses 40 as action value currently)

25. Risk Quotients • Human • AGR = RQ of 3 • PWR = RQ of 14 • Biota v 10 µGy/h (using reptile as most affected) • AGR = RQ of 0.14 • PWR = RQ of 0.64 • Biota v 40 µGy/h (using reptile as most affected) • AGR = RQ of 0.035 • PWR = RQ of 0.16

26. Risk Quotients • Human • AGR = RQ of 3 0.36 (using Ar-41 not C-14) • PWR = RQ of 14 0.23 (using Ar-41 not C-14) • Biota v 10 µGy/h (using reptile as most affected) • AGR = RQ of 0.14 • PWR = RQ of 0.64 • Biota v 40 µGy/h (using reptile as most affected) • AGR = RQ of 0.035 • PWR = RQ of 0.16

27. Open discussion of results

28. Summary/Issues for PROTECT

29. Issues/Future • Include noble gases in the non-human assessments (unsure of actual dose predictions) • However human and biota results should change ‘proportionally’ if/when noble gases are included in biota assessments • This is a simple terrestrial only assessment (note in E&W’s no terrestrial habitat assessments ever triggered at Stage 2) • Need to expand evaluation for purposes of ICRP Committee 4 (include ICRP approach in assessment?) • Combine terrestrial and aquatic assessments