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Centre for Ecology & Hydrology – Lancaster 1 st – 3 rd April 2014.

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Presentation on theme: "Centre for Ecology & Hydrology – Lancaster 1 st – 3 rd April 2014."— Presentation transcript:

1 Centre for Ecology & Hydrology – Lancaster 1 st – 3 rd April 2014

2  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

3  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developed rapidly over the last 15 y  A number of approaches have been made freely available  Some of these have been superseded  But they are still available & are being used

4  UK  Environment Agency R&D  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)

5  Europe  FASSET (EC)  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

6  Europe  EPIC (EC)  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

7  Europe  ERICA (EC)  Developed the CR and effects (FREDERICA) databases from FASSET & EPIC  Developed FASSET dosimetry 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

8  Europe  ERICA (EC)  Developed the CR and effects (FREDERICA) databases from FASSET & EPIC  Developed FASSET dosimetry 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 ERICA supersedes 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

9  International  IAEA (2009-)  Wildlife transfer parameter handbook (in-press)  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)

10  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

11  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

12  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

13  ERICA and R&D128 both clearly identify values which have been derived via guidance approach rather than data  But have been taken as ‘values’

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

15  Some scope for ‘double accounting’ associated with daughter product half-life cut-offs  e.g. R&D128 includes all 234 Th and 234 U in DCCs for 238 U  Entering both 234 Th and 238 U 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

16  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 4746/30/2/S04)http://dx.doi.org/ / /30/2/S04


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