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Nick Beresford (CEH). What to look for when interpreting an assessment. 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 - PowerPoint PPT Presentation
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Nick Beresford (CEH)
What to look for when interpreting an assessment
www.ceh.ac.uk/PROTECT
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.ceh.ac.uk/PROTECT
Chronology
Environmental Radiological assessment approaches have developed rapidly over the last 10 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A number of approaches have been made freely available Some of these have been superseded But they are still available & are being used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.ceh.ac.uk/PROTECT
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.ceh.ac.uk/PROTECT
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.ceh.ac.uk/PROTECT
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.ceh.ac.uk/PROTECT
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
www.ceh.ac.uk/PROTECT
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 updated
ERICA supersedes both FASSET and
EPIC outputs & EA state intention to
move to ERICA (p
arameters) rather
than develop R&D128
EC PROTECT supported th
e
10µGy/h screening dose rate –
using additional data and im
proved
data selection
www.ceh.ac.uk/PROTECT
Chronology International
IAEA (2009-) Developing wildlife transfer parameter handbook and
associated on-line database Database will be maintained and updates released
annually
www.ceh.ac.uk/PROTECT
Chronology International
IAEA (2009-) Developing wildlife transfer parameter handbook and
associated on-line database Database will be maintained and updates released
annually ICRP Committee 5 (2005-)
Developing a framework (ICRP-108) Currently provided tabulated DCC values (using
ERICA methodology) and summarised effects information
Draft report presenting CR values for RAPs currently with main Commission
Will be used to update the ERICA Tool CR values
(and recalculate EMCLs)
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 CR database in supporting documentation for application in uncertainty analysis
www.ceh.ac.uk/PROTECT
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 (there’s a reason these were not included in ERICA)
www.ceh.ac.uk/PROTECT
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 values very generic and conservative
www.ceh.ac.uk/PROTECT
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.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
How do screening tiers compare?
www.ceh.ac.uk/PROTECT
Screening tier - recap
Aim - to enable sites of negligible concern to be identified and removed from need for further assessment – with a high degree of confidence
Envisaged that most sites will only need this level of assessment [i.e. ‘be screened out’]
‘Concentration limits’ Input media concentrations compared to
predefined concentrations = media concentration giving rise to screening dose rate ERICA: ‘environmental media concentration limits’
EMCLs RESRAD-BIOTA: ‘biota concentration guidelines’ BCGs
ERICA Tool - EMCLs
Estimated assuming: Habitat assumption to maximise exposure Probability distributions associated with the default
CR and Kd databases were used to determine 5th percentile EMCL
No conservatism applied to dosimetry
For aquatic ecosystems EMCL for water includes consideration of external dose from sediment and that for sediment includes external dose from water and biota-water transfer
RESRAD-BIOTA - BCGs
Estimated assuming: Infinitely large (internal) and small (external)
geometries for dose calculations Daughter T1/2’s up to 100 y included All terrestrial organisms 100% in soil; aquatic
100% water-sediment interface ‘Maximum’ CR values or 95th percentile CR
values predicted using a kinetic-allometric approach
RESRAD-BIOTA - BCGs
Estimated assuming: Infinitely large (internal) and small (external)
geometries for dose calculations Daughter T1/2’s up to 100 y included All terrestrial organisms 100% in soil; aquatic
100% water-sediment interface ‘Maximum’ CR values or 95th percentile CR
values predicted using a kinetic-allometric approach
www.ceh.ac.uk/PROTECT
Screening Tier Comparison
Run RESRAD-BIOTA, ERICA Tool and EA R&D128 against 10 µGy/h screening dose rate
Data suitable for application in screening tier assessment report – maximum media activity concentrations for Four freshwater Three terrestrial scenarios Taken from SENES-WNA report 2007
Input data - freshwaterActivity concentration (Bq l-1 or Bq kg-1)
FW1 FW2 FW3 FW4
Nuclide Water Sediment Water Sediment Water Water Sediment3H 5.60x104 2.78x103 14C 4.81x10-1
60Co 2.52x10-2 1.59x102 8.51x10-2 90Sr 1.60x10-1 6.00x102 7.50x10-3 9.60x10-1 2.74x10-1
106Ru 2.60 2.32x103 8.14x10-1 131I 1.10x10-1 1.10 1.44x10-1
137Cs 8.80x10-2 2.08x103 8.50x10-3 8.50 4.44x10-3 210Po 5.00x10-2 3.70x102 3.70x10-2 1.51x103
234U** 8.00x10-2 2.05x101 2.00 1.00x102 3.05x10-1 2.15x104
234Th*** 8.00x10-2 1.00x102 1.80 9.10x101 3.05x10-1 2.15x104
238U 8.00x10-2 1.00x102 1.80 9.10x101 3.05x10-1 2.15x104
239Pu 9.50x10-5 5.06x101 241Am 5.00x10-3 5.00x101
Input data - terrestrial
Nuclide T1 T2 T3
Soil (Bq kg-1) Air (Bq m-3) Soil (Bq kg-1) Groundwater (Bq m-3)
Soil (Bq kg-1)
3H 6.59x102 4.81x107 7.00x109
14C 4.81x10-1 2.16x103 2.37x106
60Co 4.52x102
90Sr 1.85137Cs 1.80x102 2.85x101
234U** 6.09x104 6.08234Th*** 9.40x103 6.08238U 9.40x103 6.08239Pu 7.00
EA R&D128 RESRAD-BIOTA ERICA Tool
Radionuclide
Most exposed group RQ
Most exposed group RQ
Most exposed group RQ
FW13H All organisms 5.5x10-2 Riparian animal 2.3x10-2 Phytoplankton 1.6x10-1
60Co Bacteria 9.5x10-3 Aquatic animal 1.9x10-2 Insect larvae 1.3
90SrAmphibian, Duck 4.5x10-2 Riparian animal 1.7x10-1 Insect larvae 4.9x10-2
106Ru Duck 1.8x101 n/i Insect larvae 2.0x101
137Cs Duck 4.2x10-1 Riparian animal 3.0x10-1 Insect larvae 1.7131I Duck 9.1x10-4 Riparian animal 8.9x10-4 Phytoplankton 5.3x10-3
210Po
Large benthic crustacean, Small benthic crustacean, Benthic mollusc 8.5x101 Aquatic animal 1.5x10-1 Bivalve mollusc 1.8x101
234U n/a Aquatic animal 4.3x10-1 Vascular plant 6.4x101
234Th n/a n/a Insect larvae 8.6x101
238UAmphibian, Duck 1.3x102 Aquatic animal 3.9x10-1 Vascular plant 2.7x102
239Pu Amphibian 3.0x10-1 Riparian animal 9.5x10-4 Phytoplankton 8.0x10-2
241AmAmphibian, Duck 2.5 Aquatic animal 1.2x10-2 Phytoplankton 1.9
SUM 2.4x102 1.5 4.6x102
Fre
shw
ater
EA R&D128+ RESRAD-BIOTA ERICA Tool
Radionuclide
Most exposed group RQ
Most exposed group RQ
Most exposed group RQ
FW290Sr Duck 5.7x10-4 Riparian animal 3.1x10-3 Insect larvae 2.1x10-3
137Cs Duck 1.7x10-3 Riparian animal 4.3x10-2 Insect larvae 1.1x10-3
234U n/a Aquatic animal 1.1x101 Vascular plant 3.1x102
234Th n/a n/a Insect larvae 1.9x103
238U Duck 1.2x102 Aquatic animal 8.7 Vascular plant 2.4x102
SUM 1.2x102 1.9x101 2.5x103
Freshwater
EA R&D128+ RESRAD-BIOTA ERICA Tool
Radionuclide
Most exposed group RQ
Most exposed group RQ
Most exposed group RQ
FW33H All organisms 2.7x10-3 Riparian animal 1.1x10-3 Phytoplankton 8.1x10-3
14C Duck 1.0x10-2 Riparian animal 8.5x10-2 Bird 3.1x10-2
60Co Bacteria 2.6x10-2 Aquatic animal 3.1x10-2 Insect larvae 4.690Sr Duck 2.1x10-2 Riparian animal 1.1x10-1 Insect larvae 7.8x10-2
106Ru Duck 6.2x10-1 n/i Insect larvae 6.4131I Duck 1.2x10-3 Riparian animal 1.2x10-3 Phytoplankton 6.9x10-3
137Cs Duck 8.9x10-4 Riparian animal 1.1x10-2 Insect larvae 8.7x10-2
SUM 6.9x10-1 2.4x10-1 1.1x101
Freshwater
EA R&D128 RESRAD-BIOTA ERICA Tool
RadionuclideMost exposed
group RQMost exposed
group RQMost exposed
group RQ
FW4
210Po
Large benthic crustacean, Small benthic crustacean, Benthic mollusc 3.5x102 Aquatic animal 1.1x10-1 Bivalve mollusc 1.4x101
234U n/a Aquatic animal 1.6 Vascular plant 6.7x104
234Th n/a n/a Insect larvae 3.3x102
238U Duck 2.9x104 Aquatic animal 2.0 Vascular plant 5.7x104
SUM 2.9x104 4.6 1.3x105
Freshwater
EA R&D128 RESRAD-BIOTA ERICA Tool
RadionuclideMost exposed
group RQMost exposed
group RQMost exposed
group RQ
FW4
210Po
Large benthic crustacean, Small benthic crustacean, Benthic mollusc 3.5x102 Aquatic animal 1.1x10-1 Bivalve mollusc 1.4x101
234U n/a Aquatic animal 1.6 Vascular plant 6.7x104
234Th n/a n/a Insect larvae 3.3x102
238U Duck 2.9x104 Aquatic animal 2.0 Vascular plant 5.7x104
SUM 2.9x104 4.6 1.3x105
Freshwater
U-238 – ERICA Tool and EA R&D128 RQ estimated from input sediment; kd value used estimates much higher water activity concentration than observed; RESRAD-BIOTA uses water and sediment inputs separately
EA R&D128+ RESRAD-BIOTA ERICA Tool
Radionuclide
Most exposed group RQ
Most exposed group RQ
Most exposed group RQ
FW33H All organisms 2.7x10-3 Riparian animal 1.1x10-3 Phytoplankton 8.1x10-3
14C Duck 1.0x10-2 Riparian animal 8.5x10-2 Bird 3.1x10-2
60Co Bacteria 2.6x10-2 Aquatic animal 3.1x10-2 Insect larvae 4.690Sr Duck 2.1x10-2 Riparian animal 1.1x10-1 Insect larvae 7.8x10-2
106Ru Duck 6.2x10-1 n/i Insect larvae 6.4131I Duck 1.2x10-3 Riparian animal 1.2x10-3 Phytoplankton 6.9x10-3
137Cs Duck 8.9x10-4 Riparian animal 1.1x10-2 Insect larvae 8.7x10-2
SUM 6.9x10-1 2.4x10-1 1.1x101
Freshwater
Co-60 (& Ru-106) – ERICA Tool kd values >> than values in other two models
TerrestrialEA R&D128 RESRAD-BIOTA ERICA Tool
RadionuclideLimiting organism RQ
Limiting organism RQ
Limiting organism RQ
T1137Cs Carnivorous
mammal3.6x10-2 Terrestrial
animal9.4x10-1 Mammal (Deer) 5.8x10-2
234U n/a Terrestrial animal
1.3 Lichen & bryophytes
3.7x101
234Th n/a n/a Grasses & Herbs 5.9x10-2
238U Fungi 1.4x102 Terrestrial plant 6.5x10-1 Lichen & bryophytes
6.2
239Pu Fungi 5.8x10-2 Terrestrial plant 6.0x10-4 Lichen & bryophytes
6.4x10-3
SUM 1.4x102 2.9 4.3x101
Terrestrial
T2 EA R&D128 RESRAD-BIOTA ERICA Tool3H Fungi 1.4x10-1 Terrestrial
animal3.3x101 Detritivorous
invertebrate2.5x10-1
14C Seed 6.3x10-3 Terrestrial animal
6.0x10-2 Mammal (Deer) 5.8x10-3
60Co Fungi 5.3x10-2 Terrestrial plant 8.0x10-2 Mammal (Rat) 6.1x10-2
90Sr Carnivorous mammal
5.9x10-4 Terrestrial animal
8.9x10-3 Reptile 4.9x10-3
137Cs Carnivorous mammal
5.7x10-3 Terrestrial animal
1.5x10-1 Mammal (Deer) 9.1x10-3
SUM 2.0x10-1 3.4x101 3.3x10-1
Terrestrial
EA R&D128 RESRAD-BIOTA ERICA Tool
Radionuclide
Limiting organism RQ
Limiting organism RQ
Limiting organism RQ
T3226Ra Fungi 1.8 Terrestrial plant 1.1x10-1 Lichen &
bryophytes1.3x10-1
234U n/a Terrestrial animal
1.3x10-4 Lichen & bryophytes
3.6x10-3
234Th n/a n/a Grasses & Herbs 3.8x10-5
238U Fungi 8.8x10-2 Terrestrial plant 4.2x10-4 Lichen & bryophytes
4.0x10-3
SUM 1.9 1.1x10-1 1.4x10-1
Terrestrial
T2 EA R&D128 RESRAD-BIOTA ERICA Tool3H Fungi 1.4x10-1 Terrestrial
animal3.3x101 Detritivorous
invertebrate2.5x10-1
14C Seed 6.3x10-3 Terrestrial animal
6.0x10-2 Mammal (Deer) 5.8x10-3
60Co Fungi 5.3x10-2 Terrestrial plant 8.0x10-2 Mammal (Rat) 6.1x10-2
90Sr Carnivorous mammal
5.9x10-4 Terrestrial animal
8.9x10-3 Reptile 4.9x10-3
137Cs Carnivorous mammal
5.7x10-3 Terrestrial animal
1.5x10-1 Mammal (Deer) 9.1x10-3
SUM 2.0x10-1 3.4x101 3.3x10-1
H-3 – Difference in input options RESRAD-BIOTA = soil (+ groundwater) other two models = air. Soil concentrations in excess of what would be anticipated from air.
TerrestrialEA R&D128 RESRAD-BIOTA ERICA Tool
RadionuclideLimiting organism RQ
Limiting organism RQ
Limiting organism RQ
T1137Cs Carnivorous
mammal3.6x10-2 Terrestrial
animal9.4x10-1 Mammal (Deer) 5.8x10-2
234U n/a Terrestrial animal
1.3 Lichen & bryophytes
3.7x101
234Th n/a n/a Grasses & Herbs 5.9x10-2
238U Fungi 1.4x102 Terrestrial plant 6.5x10-1 Lichen & bryophytes
6.2
239Pu Fungi 5.8x10-2 Terrestrial plant 6.0x10-4 Lichen & bryophytes
6.4x10-3
SUM 1.4x102 2.9 4.3x101
Organism – ERICA Tool and EA R&D128 include organisms with comparatively high CR values (Lichen&Bryophytes, fungi) – not included in RESRAD-BIOTA
Guidance values – Fungi U (& Ra) CR values in R&D128 are guidance values. Values used ≥10x higher than data for fungi
www.ceh.ac.uk/PROTECT
Screening tier comparison Can be considerable variation in screening tier
results Some of variation can be understood:
CR and kd (including if 95%’ile, maximum, best estimate used)
Organism How sediment and water inputs used Input options Exposure geometry
Other Tier 1 type approaches being developed Need to compare & understand before application
www.ceh.ac.uk/PROTECT
Summary Do not use/accept out of date approaches –
unless justified Ensure no misuse of default values provided
by various approaches There are differences between approaches
Dosimetric methods tend to give similar results Transfer parameters can add significant
variation Screening tiers