Transport criticality assessment methodologies for the RWMD spent fuel disposal canister transport container - 8-03

Over the past four decades or so, the UK has operated a number of reactor systems, including Magnox reactors, AGR and PWR. The UK's Nuclear Decommissioning Authority is looking at several options for the disposal of spent fuel (SF) to a Geological Disposal Facility. One concept is based on the KBS-3 design by SKB, which consists of a copper canister housing a cast iron insert (CI). The CI insert will contain several fuel assemblies. The copper canister will be transported inside a transport container, referred to as the Disposal Canister Transport Container (DCTC), and this is currently being designed. Variations around the basic KBS-3 design such as: reducing the payload, amending the package design to include neutron absorbers, filling void space with materials to reduce water density, and amending the design of the DCTC to include multiple water barriers are also being considered. The studies described in this paper also show that the transport of higher enriched fuel may not be achievable by the existing SKB (KBS-3) design