PROTECT recommendations – application in practice

1. PROTECT recommendations – application in practice

2. Outline • Overview of approaches to assessment/available assessment tools • Uncertainty/variability in model predictions • Put the PROTECT benchmark values into context of results of existing environmental assessments • Optimisation • Revisit concepts • Introduce breakouts

3. IAEA EMRAS Biota Working Group

4. Internal dose rates • Internal dose estimates generally all within 20 % of mean (of predictions) • exception being for U-238: two approaches including U-234 as daughter (resulting in 2x higher DCC)

5. External dose rates • Considerably more variable between models – especially for β- emitters

6. e.g. Duck on soil surface predictions for Sr-90

7. External dose rates • More variable between models – especially for β- emitters • Especially H-3 & C-14 (e.g. external DCC for duck on soil for H-3 ranged 0 to 5E-11) • Media assumptions (density and distribution of contamination) can be seen to result in some variation • Differences in approaches that do not matter: • use of specific geometries v’s nearest default • number of emissions assumed

8. Predicted activity concentrations • Considerable variation between predictions (3-orders of magnitude being common) Pu-239

9. Predicted activity concentrations • Some variation can be understood, e.g.: • Missing value guidance approach often give comparatively high estimates (often for little studied organisms) • Site specific (and national) data • Some approaches include reindeer data in derivation of CRs leading to high predictions for mammals (especially Po-210) • Tc-99 predictions had least variation • Very few data and all using similar approach

10. PROTECT WP2 comparison of screening Tier predictions • Comparison of initial screening tier againstthe same screening level (for example USDOE values adopted) • Limiting RQs compared

11. Terrestrial RESRAD-BIOTA & ERICA-Tool + EA R&D128 Variation appears to be predominantly due to transfer components

12. Example - England & Wales ‘Habitats’ assessments • Assessed 715 radioactive discharge authorisations • Screening level of 5 µG/hused • 600 authorisations did not require assessment more detailed than initial conservative level (i.e. estimate < 5 µG/h) • Only 9 sites would exceed PROTECT proposed 10 µG/h generic screening level • One site exceeds 450 µG/h • Most exposed organism at this site = marine mammal (very conservative assessment)

13. Example assessment results • Used data from SENES 2007 (report for WNA) [+ some additional ERICA case study site data + EcoMetric Chalk River Lab. report] • Considers results of published assessments for range of sites • Used presented media activity concentration data to run through ERICA Tool (Tier 2 – default parameters) to determine weighted whole-body absorbed dose rates • Most media activity concentrations presented as ‘upper bound’ or maximums • Note not all assessments considered by SENES (& ERICA) were complete assessments

14. Terrestrial assessments Marine assessments

15. Freshwater assessments

16. AECL Chalk River Laboratories

17. AECL Chalk River Laboratories

18. Summary • Generic screening value (10 µGy/h) is likely to identify sites of negligible risk (EA Habitats assessments) • The ‘taxonomic’ screening level for ‘non-vertebrates’ (450 µGy/h) attempts to account for radiosensitivity – in example assessments appears to be fit for purpose • Identifying sites requiring more refined assessment