Criticality safety in geological disposal facility - 8-06

The Nuclear Decommissioning Authority (NDA) have been charged with implementing the UK Government's policy for the long-term management of higher activity radioactive waste by planning, building and operating a geological disposal facility (GDF). The Radioactive Waste Management Directorate is in the early stages of planning for implementation. The licensing process will include close examination of detailed safety cases covering all aspects of the disposal system. It will not be possible to produce a full safety case until we have a site and detailed design for a GDF. At this stage our safety case is based on our understanding of the scientific and engineering principles supporting geological disposal and as it is not specific to a site or geology, we call it a 'generic' safety case. A suite of documents form our generic Disposal System Safety Case (DSSC). The paper describes how, for a GDF, criticality safety is to be ensured, including how criticality safety: is addressed in the generic safety case, using illustrative concept examples; may be communicated to non-specialists, within and outside the nuclear industry, including 'identification/articulation' of (key) contributions to safety; is supported by detailed criticality safety assessments; and is being dealt with for the post-closure phase. The paper gives context for associated papers presented at this conference which give greater detail of specific aspects of some of our criticality safety assessments for the transport, operational and post-closure phases. (authors)