k.l. smith & c.a. robinson enviros consulting ltd & a.t.k. ikonen, posiva oy

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


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


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


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…


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


Plan of ONKALO and repository

Acknowledgement: plan from Posiva Oy website


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:


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


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)


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’


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).


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


Landscape predictions 5850 years AP

Reference ecosystems selected for test case

Marine/coastalFreshwater

WetlandAgriculture/grassland

Forest


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


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)


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


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


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.


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


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


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


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


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);


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


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;


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


‘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


‘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


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;

k.l. smith & c.a. robinson enviros consulting ltd & a.t.k. ikonen, posiva oy

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