centre for ecology & hydrology – lancaster 1 st – 3 rd april 2014
TRANSCRIPT
What to look for when interpreting an assessment
Centre for Ecology & Hydrology – Lancaster1st – 3rd April 2014
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
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A number of approaches have been made freely available Some of these have been superseded But they are still available & are being used
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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)
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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
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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
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Chronology Europe
ERICA (EC) 2004-2007 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
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Chronology Europe
ERICA (EC) 2004-2007 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 updatedwww.radioecology-exchange.org
ERICA supersedes both FASSET and
EPIC outputs & EA state intention to
move to ERICA (p
arameters)
EC PROTECT supported th
e
10µGy/h screening dose rate –
using additional data and im
proved
data selection
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)
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www.ceh.ac.uk/PROTECT
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
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
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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 conservativewww.radioecology-exchange.org
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
www.ceh.ac.uk/PROTECT
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
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 fo
r assessments of n
atural
radionuclides
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