Dual Fluid Reactor as a long-term burner of actinides in spent nuclear fuel

Motivated by some previous steady-state burnup calculations (J. Sierchula et al. IJER 43, 3692 (2019)) we study the Dual Fluid Reactor metallic (DFRm) eutectic design with different fuel compositions. It is just the spent nuclear fuel (SNF) from Light Water Reactors with reactor-grade Plutonium as the fissile material. The isotope vector used here contains all important isotopes up to(243)Am. Two SNF fuel compositions are studied. One of them is appended with some fraction (0.578%) of(235)U (natural Uranium), while another is just the typical SNF without this extra isotope. In both cases one achieves fuel burnup above 225 MWd/kg, higher yield of average number of neutrons nu over bar (up to 2.94), and higher conversion ratios (up to 1.42) as compared to previous DFRm Uranium fuel composition (enriched 13.44% Uranium). However, the application of a standard SNF with no natural Uranium requires the modification of core geometry as compared to a previous design. Our results also show a significant reduction of(237)Np and Am isotopes while keeping high breeding capabilities. With SNF Plutonium fuel, as compared to just enriched Uranium fuel, one is able to extend more the DFRm operation time without fuel replacement so that this reactor may act as a 20-year lasting nuclear battery.

Automated summary

Motivated by previous steady-state burnup calculations, this study investigates the impact of different fuel compositions in the Dual Fluid Reactor metallic eutectic design, showing that using spent nuclear fuel and reactor-grade Plutonium fuel can achieve higher burnup and neutron numbers but requires adjustments to core geometry. Compared to using only enriched Uranium fuel, using spent nuclear fuel with Plutonium allows for longer operation time of the reactor.