Abstract :
The objective of the Nirex Science Programme is to evaluate the post-closure safety performance of a deep repository for intermediate level wastes (both long and short lived) and some low level wastes at a site near Sellafield in West Cumbria. The extensive surface-based site characterization programme, complemented by research and assessment studies, has established the potential suitability of the Sellafield site for the deep repository. However, a stage of underground investigations, the Rock Characterization Facility, is needed in order to establish the high level of confidence necessary to underpin a decision on whether to propose development of a repository, and subsequently a decision by the regulators to authorize commencement of disposal operations in the repository when it is constructed. The Rock Characterization Facility will be developed in three phases, providing a scientific programme lasting around ten years. It will address three key areas of uncertainty as follows: (1) groundwater flow and radionuclide transport; (2) natural and induced changes to the geological barrier; (3) design and construction of the repository. The nature of these uncertainties, the way in which underground investigations enable us to resolve them, and the design of the Rock Characterization Facility and its experimental programme to deliver the required information to resolve these uncertainties are described in this paper.
