Session: 08-02: New Facility Planning/ Environmental Management (EM)/ Health & Safety

Paper Number: 110080

110080 - Site Investigation and Design Optimisation for Potential Near Surface Disposal Facilities at the United Kingdom Low Level Waste Repository 

The United Kingdom Nuclear Decommissioning Authority (NDA) is exploring the benefits of developing Near Surface Disposal (NSD) facilities for disposing of some of the United Kingdom’s higher-activity waste (HAW). NSD facilities could bring benefits to the NDA estate, for example by freeing up space in Sellafield’s Intermediate Level Waste stores, which could then be used for other wastes to support high-hazard reduction. It would also reduce the amount of waste currently destined for the deep disposal facility, which is not expected to be available until later this century.  The NDA have asked the Low Level Waste Repository (LLWR) to examine the potential of the LLWR site to host such facilities.  The site currently takes containerised Low Level Waste for disposal in engineered vaults at surface. Disposal of HAW would require new facilities to be constructed or existing facilities to be modified. Several different types of facilities are being investigated, including vaults at the surface and silos several tens of metres below the surface. LLWR are working to provide information on feasibility of NSD to the NDA by June 2023.

To support this LLWR have implemented a site investigation programme to provide the geological, geotechnical and hydrogeological information to support the design optimisation process for a silo-type facility that would extend up to 100m below ground level.  The information collected informs not only the NSD design but also provides additional data to support the safety case for the existing facility.

The site investigation results are being used to inform the constructability assessment including how any water generated during construction will be managed, identifying suitable excavation techniques and consideration of what engineered barriers may be required. An assessment of the infrastructure required to support construction, operation and closure phases is also being carried out, and how these requirements could be accommodated on the LLWR site. This will allow an optimised design to be selected and a business case developed. Subject to approval from by the NDA, LLWR would look to incorporate the NSD into its next Environmental Safety Case, which is due to be submitted the environmental regulators in 2026. If the case for a NSD is accepted by the environmental regulator then LLWR would need to apply for development permission from local government. It is expected that no construction work would commence before 2030.

Presenting Author: John Shevelan Nuclear Waste Services

Presenting Author Biography: John holds a degree in Industrial Geology, a master’s degree in Construction Engineering and a PhD in Hydrogeology. He has worked on both conventional waste and nuclear sites carrying out site investigation work, developing environmental monitoring and remediation programmes and hydrogeological risk assessments. He has worked at LLW Repository Ltd since 2008, initially to support the delivery of the 2011 Environmental Safety Case (ESC) but since 2013 he has been the Site Characterisation Manager responsible for the delivery of the environmental monitoring and site characterisation programme and to continue to develop geological and hydrogeological modelling to support the next Environmental Safety Case.