PROTECT Workshop, Jan 08Slide 1
PROTECT Workshop, Jan 08
Demonstration Assessment of Doses to Non-human Biota from Olkiluoto
Repository and General Considerations for Waste Repository Assessments
K.L. Smith & C.A. RobinsonEnviros Consulting Ltd
&A.T.K. Ikonen, Posiva Oy
PROTECT Workshop, Jan 08Slide 3
Overview of presentation
General features of waste repository assessments
Demonstration assessment process for Olkiluoto repository (for Posiva Oy)
BIOPROTA Forum, January 07
Future – current BIOPROTA plans
PROTECT Workshop, Jan 08Slide 4
Repository assessments: what makes them different?
Sub-surface source• Relative importance of different ecosystems and organisms
• Significance of pathways of exposure
Timescales• Releases may be extended – may affect different generations
• Evolution and climate change
Radionuclides• Long-lived
• Key nuclides identified by BIOPROTA: Cl-36, Se-79, Tc-99, I-129, Pb-210, Po-210, Ra-226, Th-230, Np-237, and U-238
PROTECT Workshop, Jan 08Slide 5
Assessment process
Problem formulation or setting the scope• Generic or specific (conservatism or realism)
• Regulatory or research
Developing an approach• Information and methods available
• Proportionality
A test case…
PROTECT Workshop, Jan 08Slide 6
Demonstration assessment for the waste repository at Olkiluoto
Decision in principle in favour of geological repository at Olkiluoto, southwest Finland
Disposal due to commence in 2020
Regulated by the Radiation and Nuclear Safety Authority (STUK)
Posiva Oy responsible for development of repository
Broad safety case assessment (SCA) being developed
PROTECT Workshop, Jan 08Slide 7
Plan of ONKALO and repository
Acknowledgement: plan from Posiva Oy website
PROTECT Workshop, Jan 08Slide 8
Start of work September 2004
Drilling grout holes
ONKALO construction and investigations
http://www.posiva.fi/englanti/ONKALO-esite_EN_140605.pdf
Acknowledgement: photos from Posiva Oy website:
PROTECT Workshop, Jan 08Slide 9
Demonstration assessment process for the Olkiluoto repository
Study objectives
• Regulatory requirement
• Choice of methodology
Test Case Assessment
• Selection of assessment ecosystems and biota
• Features of test case scenario
• Methodology applied
Indicative results
Acknowledgement: photo from Posiva Oy website
PROTECT Workshop, Jan 08Slide 10
Regulatory Requirement
‘exposures shall remain clearly below the levels which, on the basis of the best available scientific knowledge, would
cause decline in biodiversity or other significant detriment to any living population. Moreover, rare animals and plants as well as domestic animals shall not be exposed detrimentally
as individuals’
(STUK, 2001, Document YVL 8.4)
PROTECT Workshop, Jan 08Slide 11
Regulatory Requirements
SCA therefore required to demonstrate (in addition to human protection criteria):
• No decline in biodiversity of current living populations
• No significant detriment to populations of fauna and flora
• No detrimental effects on individuals of domestic animals and rare animals and plants
Some assessment assumptions defined:• Present kind of living populations;
• Period of ‘several thousand years’
PROTECT Workshop, Jan 08Slide 12
Choice of Assessment Methodology Review of available and developing methodologies and
applicability to the Olkiluoto site Methods primarily based on a ‘reference organism’
approach and organisms representative of the local ecosystem
EPIC and FASSET/ERICA most comprehensive methodologies available
• EPIC - arctic ecosystem likely to more closely represent local conditions (though data gaps remain);
• FASSET/ERICA – provided data for a range of European ecosystems & wide range of reference organisms (tool not available at time of assessment).
PROTECT Workshop, Jan 08Slide 13
Environment around Olkiluoto Island to southwest of Finnish mainland Typical habitats (interwoven)
• Shallow bays
• Forests
• Nutrient rich mires
• Meadows
Sub-arctic climate Under-going post-glacial land uplift
Wetlands Forest/agricultureMarine/coastal areas
PROTECT Workshop, Jan 08Slide 14
Landscape predictions 5850 years AP
Reference ecosystems selected for test case
Marine/coastalFreshwater
WetlandAgriculture/grassland
Forest
PROTECT Workshop, Jan 08Slide 15
Identification of relevant biota STUK requirement
• Present kinds of living populations
• Individuals of rare/sensitive species
• Domestic animals
Generic organisms• Simple food webs
Interest species • Natura 2000 site descriptions
• Agricultural statistics
• Game statistics
• Local knowledge – species of public interest
Interest species
PROTECT Workshop, Jan 08Slide 16
Identification of relevant biota (2) Sub-set of organisms selected and assigned to ecosystems
• Occupancy within ecosystem compartments likely to result in increased dose
• Demonstration of individual endpoints compared to population;
• Migration between ecosystems (e.g. moose)
Organisms assigned, on basis of general biota characteristics:
• Concentration ratios
• Ellipsoid geometries (and associated dose conversion factors)
• Occupancy factors (on or within soil, sediment & water) – taking account of climate
• Migratory occupancy (between ecosystems)
PROTECT Workshop, Jan 08Slide 17
Test case organisms – Forest
Generic Interest species
Grass / herbShrubTreeWorm Burrowing herbivorous mammal Large herbivorous mammal
Average CR values & general habit data
Wolf BearMooseEuropean HareRare/sensitive Plant
Maximal CR values & habit data
PROTECT Workshop, Jan 08Slide 18
Migratory Interest creatures and occupancy assumptions
Interest / Reference Creature Marine Freshwater Wetland
Agriculture/ Grassland Forest
Wolf 0.2 0.8
Bear 0.1 0.9
Moose 0.3 0.1 0.6
Otter 0.5 0.5
Goose 0.5 0.5
European hare 0.5 0.5
Salmon 0.5 0.5
PROTECT Workshop, Jan 08Slide 19
Test case PANDORA was used to (by Facilia) provide activity concentrations in
water, soil and sediment as a function of time within defined biosphere compartments;
Scenario based on assumed source term locations normalised to total 1 Bq/y for each of the following radionuclides into the overall landscape:
• Cl-36, Ni-59, Se-79, Tc-99, I-129, Cs-135, Po-210, Pb-210, Ra-226, Pu-239, U-234, U-238, Np-237.
The highest activity concentrations occurring at 10,000 years in each ecosystem type were identified for 1 Bq/y case;
Source term information for 10,000 years for full canister disintegration;
The maximum source term values (in 1 million years) also used for scoping.
PROTECT Workshop, Jan 08Slide 20
Freshwater - disappearing canister scenario
0.00E+00
2.00E-34
4.00E-34
6.00E-34
8.00E-34
1.00E-33
1.20E-33
1.40E-33
1.60E-33
Phy
topl
ankt
on
Zoo
plan
kton
Vas
cula
r pl
ant
Ben
thic
mol
lusc
Ben
thic
cru
stac
ean
Ben
thic
fis
h
Pel
agic
fis
h
Duc
k
Bird
Inse
ct
Ott
er
Fre
shw
ater
pea
rl m
usse
l
Sal
mon
µG
y/h
Pu-239
Np-237
U-238
U-234
Th-230
Ra-226
Cs-135
I-129
Tc-99
Se-79
Ni-59
Cl-36
PROTECT Workshop, Jan 08Slide 21
Forest - disappearing canister scenario
0.00E+00
5.00E-31
1.00E-30
1.50E-30
2.00E-30
2.50E-30
3.00E-30
Bird
Wor
m
Bird
egg
Mon
ocot
yled
on
Tre
e
Sm
all
herb
ivor
ous
Car
nivo
rous
mam
mal
Bur
row
ing
mam
mal
Larg
ehe
rbiv
orou
s
Dog
/wol
f
Bea
r
Moo
se
Har
e
Pla
nt
µG
y/h
Pu-239
Np-237
U-238
U-234
Th-230
Ra-226
Cs-135
I-129
Tc-99
Se-79
Ni-59
Cl-36
PROTECT Workshop, Jan 08Slide 22
Maximum exposed creatures and principal dose contributors
Ecosystem Reference creature
Interest species Principal Radionuclide(s)
Marine Phytoplankton Salmon Pu-239
Freshwater Vascular plant Freshwater pearl mussel
Pu-239
Wetland Bird egg Plant Cl-36
Agriculture / grassland
Bird egg Plant Pu-239, Cl-36, I-129
Forest Worm Plant Pu-239
PROTECT Workshop, Jan 08Slide 23
Highest dose under worst-case assumptions
Ecosystem Creature Dose rate (µGy/h)
Marine Otter 7.65E-09
Freshwater Vascular plant 7.32E-09
Wetland Bird egg 8.98E-11
Agriculture / Grassland
Sensitive plant 2.33E-07
Forest Sensitive plant 3.32E-04
Even under maximising assumptions, doses do not approach those likely to cause harm to individuals or
populations
PROTECT Workshop, Jan 08Slide 24
General methodological issues Single stressor assessment (ionising radiation);
• Chemical toxicity of radionuclides and of non-radioactive releases;
Assessment of population and community effects;• Population dynamics;
• Interdependency of different organisms.
Dose rate benchmarks and effects analysis;• Limited data available for key creatures (e.g. for large
mammals);
PROTECT Workshop, Jan 08Slide 25
General dose assessment issues Generic equilibrium concentration ratios and distribution
coefficients;• Limited database for some organisms and radionuclides;
• Examples include large mammals (…)
• Generic assumptions not necessarily applicable to all environments/organisms;
Dose conversion coefficients• Mammals
Dose rate weighting factors to allow for RBE of different radiation types
PROTECT Workshop, Jan 08Slide 26
Specific issues for long-term releases of long-lived
radionuclides Treatment of climate and landscape change; Long-lived nuclide-specific data availability Dealing with uncertainties, probabilistic assessment and
communication;
PROTECT Workshop, Jan 08Slide 27
BIOPROTA A forum to address uncertainties in the assessment of the
radiological impact of releases of long lived radionuclides in to the biosphere (from solid waste disposal facilities)
Commonly focused projects:• efficient use of skills and resources
• transparent and traceable basis for parameter value choice and wider interpretation of assessment information
Participants:• National authorities and agencies with responsibility for
achieving safe and acceptable radioactive waste management, both regulators and operators
• Enviros Secretariat www.bioprota.com
PROTECT Workshop, Jan 08Slide 28
‘PROBIOTA’ Forum, January 2007 Forum for the exchange
information on the suitability of the current guidance and methods for non-human biota assessments to long-term assessments
Attended by 15 participants from 6 countries (operators and technical support organisations)
Hosted by Posiva Oy,in LappeenrantaFinland
PROTECT Workshop, Jan 08Slide 29
‘PROBIOTA’ Forum identified issues Applicability of concentration ratios for assessing impacts
to NHB Dealing with site evolution over the timescales required
for waste repository PAs and the effect on ecosystems The value of sensitivity analysis to focus efforts Dealing with synergistic interactions Regulatory drivers (focus on present day knowledge and
the applicability of this to future scenarios is not clear) Communicating the results of NHB assessments Value of follow-on workshops
PROTECT Workshop, Jan 08Slide 30
BIOPROTA - Proposal for sensitivity analysis
Evaluate the robustness of assessment data in relation to the key long-lived radionuclides applicable to deep geological disposal facilities;
Identify important data gaps and uncertainties related to biota dose assessment upon which future tasks may be identified;
Determine the impact of given release scenario assumptions and climate variations on calculated dose rate;
Evaluate the potential range of parameter values used in the assessment, the availability and ‘robustness’ of data;
Undertake a sensitivity analysis to identify the parameters and uncertainties that contribute most significantly to the overall results;
Perform a knowledge quality assessment to identify key gaps in data and understanding;