centre for ecology & hydrology – lancaster 1 st – 3 rd april 2014

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A number of approaches have been made freely available Some of these have been superseded But they are still available & are being used


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)


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


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


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


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)


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


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’



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


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

http://dx.doi.org/10.1088/0952-4746/30/2/S04

centre for ecology & hydrology – lancaster 1 st – 3 rd april 2014

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