Analysis of Critical Issues in Biosphere Assessment Modelling and Site Investigation

SUMMARY: The aim of this document is to present a critical review of issues concer-ned with the treatment of the biosphere and geosphere-biosphere interface in long-term performance assessment studies for nuclear waste disposal in Sweden. The review covers three main areas of investigation: • a review of SKB’s plans for undertaking site investigations at candidate loca-tions for the development of a deep geological repository for spent fuel; • identification of critical uncertainties associated with SKB’s treatment of the geosphere-biosphere interface in recent performance assessments; and • a preliminary modelling investigation of the significance of features, events and processes in the near-surface environment in terms of their effect on the accumu-lation and redistribution of radionuclides at the geosphere-biosphere interface. Overall, SKB’s proposals for site investigations are considered to be comprehensive and, if they can be carried out to the specification presented, will constitute a bench-mark that other waste management organisations will have to work hard to emulate. The main concern is that expertise for undertaking the investigations and reportin