Lattice Physics Study of Various Fuel Assembly Design and Optimization Based on Neutronic Analysis for PT-SCWR

Abstract The pressure-tube type supercritical water-cooled reactor (PT-SCWR) is a Canadian Generation IV concept advanced reactor designed for higher system pressure and enhanced thermal efficiency. Operating at 25 MPa pressure and temperatures ranging from 350 °C to 625 °C, it achieves over 45% power conversion efficiency. The large variation of coolant density in the core by more than a factor of seven is the driving force for this in-depth core neutronic analysis. Improving lattice parameters in order to achieve the right balance between coolant void reactivity (CVR) and fuel utilization is a major difficulty in the reactor’s physics design. The PT-SCWR features detachable fuel components in pressure tubes immersed in a heavy water moderator. This research focuses on lattice physics and core neutronic analysis, utilizing the DRAGON neutron transport code. Various fuel assembly configurations, including several radial enrichment profiles for different fuels and optimized central rod constituents, were examined for improved safety and efficiency. Innovations, like a two-ring fuel assembly with a central flow tube, enhance fuel exit burnup and reduce coolant void reactivity. The study demonstrates the safety improvements through optimized bundles, meeting criteria for fissile fuel usage and negative coolant reactivity coefficients.