Report 2010-3

Biosphere Assessment Report 2009

Hjerpe,T., Ikonen, A.T.K. & Broed, R.

English

186

978-951-652-174-2

Following the guidelines set forth by the Ministry of Trade and Industry (now Ministry of Employment and Economy), Posiva is preparing to submit a construction license application for the final disposal spent nuclear fuel at the Olkiluoto site, Finland, by the end of the year 2012. Disposal will take place in a geological repository implemented according to the KBS-3 method. The long-term safety section supporting the license application will be based on a safety case that, according to the internationally adopted definition, will be a compilation of the evidence, analyses and arguments that quantify and substantiate the safety and the level of expert confidence in the safety of the planned repository. The present Biosphere Assessment Report represents a major contribution to the development this safety case. The report has been compiled in accordance with Posiva’s current plan for preparing this safety case. A full safety case, and an updated Biosphere Assessment Report, will be developed to support the Preliminary Safety Assessment Report (PSAR) in 2012.

This report summarises the biosphere assessment for the planned repository addressing the following components: the site understanding (biosphere description), development of terrain and ecosystems within the next ten millennia, calculations of radionuclide transport in the biosphere and radiological consequences analysis, i.e. dose assessments for humans and the other biota. It also presents the main models used in the assessment and summarises the input data and its quality. It discusses compliance with Finnish regulatory requirements for long-term safety of a geological repository on the basis of the calculated annual effective doses to representative members of the most exposed people and to the a larger group of exposed people and typical absorbed dose rates to plants and animals. The other aspects of the compliance are addressed in the interim Summary Report of the safety case.

Various repository calculation cases have been considered in which failure of a single spent fuel canister gives radionuclide releases to the biosphere within the biosphere assessment time window of ten millennia. It is shown that the resulting doses to humans and other species of flora and fauna imply that any radiological consequences of these releases will be negligible. Plans are in place to manage remaining issues and uncertainties, as given in the report TKS-2009 so that a comprehensive safety case will be developed to support the licensing process.

Safety case, safety assessment, KBS-3V, KBS-3H, spent fuel repository

Biosphere Assessment Report 2009 (pdf) (6.5 MB)