Transuranic transmutation efficiency of a small fusion–fission facility for spent uranium-oxide and inert matrix fuels

The transmutation efficiency of a Fusion facility to Burn Fission Waste (FBFW) based on a Spherical Tokamak (ST) neutron source is investigated. The perfomances are analyzed based on two different fuel cycles. The first fuel cycle assumes separation of all Transuranics elements (TRU) from Spent Nuclear Fuel (SNF) and then burning in FBFW; the second fuel cycle considers a first burning of fissile TRUs in Light Water Reactors (LWR) using an Inert Matrix Fuel (IMF). It is found that the FBFW (1 GWe) can support 5.8 LWR plants (1 GWe) or 19 LWR plants (1 GWe) for IMF fuel cycle. The neutron-dependent characteristics of the system, such as keff and Tritium Breeding Ratio (TBR), are investigated. The TBR is found to be strongly dependent on keff and a three-batch strategy is proven to be sufficient to maintain a moderate fusion power (<200 MW) and a satisfactory batch burn-up for IMF fuel cycle.