Transuranium Fuel Assembly for Transmutation in a Pressurized Water Reactor

Results are presented of a conceptual design study of a transuranium (TRU) fuel assembly consisting of only plutonium and minor actinide (MA) oxides for transmutation of MAs in a pressurized water reactor (PWR). The average plutonium content of the TRU transmutation fuel assembly in this study is 38 wt% Putot, and the average MA content is 62 wt%. The fuel rod arrangement and the plutonium content are optimized to suppress the internal power peaking in the fuel assembly. Core characteristics and TRU inventory change are evaluated for an 870-MW(electric) PWR core loaded heterogeneously with a few TRU transmutation fuel assemblies. The maximum loading of the TRU transmutation fuel is limited to nine assemblies to maintain a negative moderator temperature coefficient at the beginning of cycle, while satisfying a cycle length of 15.2 GWd/tonne U. By loading nine TRU transmutation fuel assemblies, the total MA inventory in the core decreases by ∼65 kg/cycle, which is approximately equivalent to that produced from three UO2 reactors. The heterogeneous loading of a few fuel assemblies with highly concentrated TRU in a PWR is found to be feasible for the effective transmutation of MAs while maintaining reactor safety.