Experiences from testing the ERICA Integrated Approach Case study application of the ERICA Tool and D-ERICA

Objectives To assess the applicability of draft versions of D- ERICA and ERICA Tool To compare predicted and observed activity concentrations in biota (and water/sediments for aquatic ecosystems) Where possible, to compare observed radiation induced effects with estimated doses and predicted effects To make recommendations to the ERICA consortium

Drigg Coast Sand Dunes UK (WSC, Uni. Liverpool) Natura 2000 site – receiving contamination from Sellafield marine discharges Opportunity to address identified deficits in FASSET methodology & respond to stakeholders ERICA sampling campaign Full role-play assessment of regulated site

Loire River (EDF) River receives discharges from a number of nuclear power plants Opportunity to compare ERICA predictions to those of model developed specifically to assess the Loire

Sellafield Marine (NRPA & WSC) Anthropogenically contaminated marine site Comparatively large database available (1980 and 2005 assessed) Opportunity to compare with site specific model predictions Full role-play assessment of regulated site

Komi Republic (NRPA & IOB) High levels of natural radionuclides (Th and U series) – range of historical practices Comparatively large database now available Biological effects studies in area

Chernobyl (CEH & IRL) ERICA study to measure external dose rates to small mammals at three sites using attached TLDs (within 10 km zone) Large database of whole- body activity concentrations available for wide range of biota (predominantly Cs & Sr, some actinides)

Exposure to background radiation Drigg case study Tier 2 conservative RQ > 1 due to natural background radionuclides ERICA is for assessment of incremental dose rates Example of poor definition of ERICA Integrated Approach in draft documentation Now clearly stated and discussed

Conservatism at Tier 2 Tier 2 conservative dose rate should ≈ Tier 3 95 th %ile estimate Sellafield Marine Case Study (using one of two possible media inputs) Tier th %ile higher than Tier 2 conservative estimate

Conservatism at Tier 2 Tier 2 conservative dose rate should ≈ Tier 3 95 th %ile estimate Sellafield Marine Case Study (using one of two possible media inputs) Tier th %ile higher than Tier 2 conservative estimate Not observed for other case studies (some reservations re input water concentrations)

Conservatism at Tier 2 Tier 2 conservative dose rate should ≈ Tier 3 95 th %ile estimate Sellafield Marine Case Study (using one of two possible media inputs) Tier th %ile higher than Tier 2 conservative estimate Not observed for other case studies (some reservations re input water concentrations) Need to further test Tier 2 ‘uncertainty factor assumptions’ –in PROTECT scenarios?

Lichen Lichen and Bryophyte’ reference organism is the limiting organism for a number of radionuclides (mostly natural isotopes). –for 210Po, the associated EMCL value of 25 Bq kg-1 DW soil due to high CR The use of a soil-biota CR may not be applicable Acute exposure data (for mortality) suggest that lichens have a low radiosensitivity. Implementation of a predicted no effects dose rate (as used to define the screening dose-rate at Tiers 1 and 2) derived to be protective of all organism types within terrestrial ecosystems may be overly conservative for lichens and mosses.

Transfer parameters - Chernobyl Generally good agreement all species – Sr, Pu, Am, Cs

Transfer parameters - Chernobyl Generally good agreement all species – Sr, Pu, Am, Cs –Tier 3: some predicted 95 th %ile < maximum observed

Transfer Parameters - Komi Generally Ra-226, Th-232 & U-238 ‘agree well’ or are over predicted (ash weight soil used): –Ra-226 tree under predicted –U-238 & Th-232 under predicted voles [limited data available] –Non-linearity (potential but not investigated)?

Transfer parameters - Drigg Cs-137 consistently over predicted (1-2 orders of magnitude) –Most default data relate to post Chernobyl studies (likely to be for organic soils) Am-241 under predicted in higher plants –Site receives aerial deposition (sea-land) A number of CR values tested were ‘guidance values’ – gave reasonable predictions

Transfer parameters - freshwater No case study tested freshwater CR values –ERICA participating in EMRAS BWG freshwater scenario Test version K d values criticised as being ‘old’ –Updated with EMRAS TRS364rev outputs

Transfer parameters - Marine For Pu, Am and Cs – generally reasonable agreement –Over predicted fish Pu [but observed data edible tissues not whole-body] –Cs-137 activity concentrations in seabirds 500x higher than observed data [observed data all for gull sp. – feeding in terrestrial ecosystems?]

Dosimetry Chernobyl case study – predicted external dose rate predictions agreed well with measurements from ‘TLD- collars’ Komi and Chernobyl – reasonable agreement between gamma air kerma rates and predicted external dose rates (& TLD results for Chernobyl) Include ability to input dose rates ? Include advice that gamma air kerma rates can be used to verify external dose rate predictions ?

Dosimetry – create organism Restriction on size: – to 550 kg on soil – to 6.6 kg in soil –0.035 to 2 kg for flying animals Limits usefulness (e.g. for European bat spp., large burrowing animals etc.) –Revised Help documents limitations and provides advice on approaches to best model user defined organisms (& limitations) –Limitations more obvious on Tool screen

Effects summaries Tier 2 effects summaries criticised as not being very useful (often lots of contradictory data or no data) Now improved - summary’ by dose range

Tier 3 link to FREDERICA Criticised as being of little aid to decision maker as expert interpretation would be required –But this is Tier 3 and it is anticipated that experts will need to be consulted –FREDERICA is an up to date, freely accessible database which provides a useful expert tool (others outside the ERICA consortium are using it [e.g. Chambers et al. 2006])

ERICA outputs – the future Consortium agreement to manage potential Tool development and maintain databases Tool and databases will continue to participate within IAEA EMRAS BWG scenarios (outputs available end 2007) ERICA outputs will be assessed within the PROTECT project Special issue of J. Environ. Radioact. in preparation