2010:38 The feasibility of Backfilling a Repository of Spent Fuel: An Assessment of Recent Developments by SKB

In the Review Statement and Evaluation of SKB’s RD & D programme 2007 (SKI Report 2008:48E), the former Swedish Nuclear Power Inspectorate (SKI) commented that considerable work remained to be done for knowledge of both practical management issues on backfilling and analysis of long-term backfill evolution to reach the same level as for the canister and the buffer. SKI considered that the backfill material had not been thoroughly reported in the RD & D programme. More concrete plans were also needed relating to large-scale demonstration experiments to investigate the performance of the backfill in as realistic conditions as possible.

In the spring of 2009, noting that SKB had changed its concept for backfilling several times over the last few years, and after having visited SKB’s most recent backfilling trials at Äspö, both SSM and SSM’s expert group BRITE had strong concerns regarding SKB’s programme for backfilling the repository tunnels.

Although the BRITE expert group has been keeping a watching brief over SKB’s development work on backfilling, SSM has not undertaken a systematic assessment of SKB’s work in this area since the SR-Can Safety Report was reviewed in 2006. Dr David Bennett, a member and secretary of the BRITE expert group, was asked to do such an assessment. This report describes the assessment results.