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What to look for when interpreting an assessment

Explore the chronology of environmental radiological assessment approaches, from the UK's Environment Agency to international bodies like ERICA and IAEA, highlighting methodological developments and tools available, such as FASSET, EPIC, ERICA, and USDOE's graded approach. Understand the importance of avoiding misuse of default values in assessments and making informed choices based on evolving practices in radioecology.

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What to look for when interpreting an assessment

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  1. What to look for when interpreting an assessment Centre for Ecology & Hydrology – Lancaster 1st – 3rd April 2014

  2. Objective • Give an overview of what may impact on assessment results using the available approaches • In part based on things we know are being done • Consider chronology of development, misuse of default values, double accounting, screening tier application • Not considering dispersion modelling and sampling strategies www.radioecology-exchange.org

  3. Chronology • Environmental Radiological assessment approaches have developed rapidly over the last 15 y • A number of approaches have been made freely available • Some of these have been superseded • But they are still available & are being used www.radioecology-exchange.org

  4. Chronology • UK • Environment Agency R&D128 - 2001 • Spreadsheet model for limited number of radionuclides • Comparatively limited review to derive CR values • Dosimetry methods similar to later approaches • Environment Agency Sp1a – 2003 • Supports R&D128 including derivation of complete CR data sets using a ‘guidance approach’ (can be extremely conservative) www.radioecology-exchange.org

  5. Chronology • Europe • FASSET (EC) 2001-2004 • Establish a framework for radiological environmental protection from source characterisation – interpretation, including: • Tabulated CR and DCC values for: • radionuclides of 20 elements • circa 30 reference organism in 7 ecosystems • Developed the on-line FASSET Radiation Effects Database www.radioecology-exchange.org

  6. Chronology • Europe • EPIC (EC) 2000-2003 • Establish a framework for radiological environmental protection for the Arctic • Ran concurrent to FASSET and shared CR database • Although presented differently and for only 12 radionuclides • DCCs derived by a different method • Allowed participation of Russian institutes leading to EPIC effects database www.radioecology-exchange.org

  7. Chronology • Europe • ERICA (EC) 2004-2007 • Developed the CR and effects (FREDERICA) databases from FASSET & EPIC • Developed FASSETdosimetry methodology • Adapted ‘guidance’ for selecting missing CRs from EA SP1a • Output - the ERICA Tool implementing the ERICA Integrated Approach • More generic ecosystem types (because of lack of data) than FASSET and adapted reference organism list (to encapsulate European protect species & remove some unjustified sub-categories) • Derived 10 µGy/h screening dose rate (by SSD) • Being maintained and updated www.radioecology-exchange.org

  8. Chronology • Europe • ERICA (EC) 2004-2007 • Developed the CR and effects (FREDERICA) databases from FASSET & EPIC • Developed FASSETdosimetry methodology • Adapted ‘guidance’ for selecting missing CRs from EA SP1a • Output - the ERICA Tool implementing the ERICA integrated approach • More generic ecosystem types (because of lack of data) than FASSET and adapted reference organism list (to encapsulate European protect species & remove some unjustified sub-categories) • Being maintained and updated ERICAsupersedes both FASSET and EPIC outputs & EA state intention to move to ERICA (parameters) EC PROTECT supported the 10µGy/h screening dose rate – using additional data and improved data selection www.radioecology-exchange.org

  9. Chronology • International • IAEA (2009-) • Wildlife transfer parameter handbook (in-press) • 2013 - initiate group to draft Volume III of ‘Generic models for use in assessing the impact of discharges of radioactive substances to the environment’ Volume III considers wildlife. • ICRP Committee 5 (2005-) • Provided tabulated DCC values (using ERICA methodology) and summarised effects information (ICRP-108) • Report presenting CR values for RAPs (ICRP-114) www.radioecology-exchange.org

  10. Chronology • USA • USDOE Graded Approach (2002) • Initially supported by BCG-Calculator spreadsheet model. Still available – but replaced by: • RESRAD-BIOTA • Limited and conservative CR values for generic organisms • RESRAD-BIOTA v1.5 (2009) includes values from the ERICA (original) CR database in supporting documentation for application in uncertainty analysis www.ceh.ac.uk/PROTECT

  11. So don’t ...... • Use out of date approaches unless you can justify why they have been used, e.g.: • OK to use R&D128 for noble gases • Not OK to use FASSET CR values because they offer more ‘refined’ reference organism list/ecosystem range .... but do be aware that this is an evolving area www.radioecology-exchange.org

  12. Misuse of default values • To serve the purpose for which they were intended RESRAD-BIOTA, R&D128(SP1a) and the ERICA Tool give a complete list of radionuclide-organism transfer parameters. • ERICA Tool and R&D128 missing values derived using ‘guidance’ approaches. These should not be blindly used in higher tier assessments nor should they be picked out for use in other models/recommendations without being clearly identified as such • RESRAD-BIOTA Biv (=CR) values very generic and conservative www.radioecology-exchange.org

  13. Misuse of default values • ERICA and R&D128 both clearly identify values which have been derived via guidance approach rather than data • But have been taken as ‘values’ www.radioecology-exchange.org

  14. Double accounting • Some scope for ‘double accounting’ associated with daughter product half-life cut-offs • e.g. R&D128 includes all 234Th and 234U in DCCs for 238U • Entering both 234Th and 238U activity concentrations would over estimate dose rates • RESRAD-BIOTA and ERICA both offer the user the opportunity to do similar www.ceh.ac.uk/PROTECT

  15. Double accounting • Some scope for ‘double accounting’ associated with daughter product half-life cut-offs • e.g. R&D128 includes all 234Th and 234U in DCCs for 238U • Entering both 234Th and 238U activity concentrations would over estimate dose rates • RESRAD-BIOTA and ERICA both offer the user the opportunity to do similar Understand what daughters are/are not included in default DCCs especially important for assessments of natural radionuclides www.ceh.ac.uk/PROTECT

  16. Summary • Do not use/accept out of date approaches – unless justified • Be aware of potential changes as a consequence of recent transfer parameter reviews & forthcoming ERICA update • Ensure no misuse of default values provided by various approaches • Use alternatives where justified • There are differences between approaches • Dosimetric methods tend to give similar results • Transfer parameters can add significant variation • Screening tiers (see http://dx.doi.org/10.1088/0952-4746/30/2/S04) www.radioecology-exchange.org

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