Development of a start-up core for sustaining rotational fuel shuffling strategy for a nitride fueled lead-cooled fast reactor

This study investigates a start-up core design for a lead-cooled fast reactor employing a Rotational Fuel-shuffling Breed-and-Burn (RFBB) strategy using High-Assay Low-Enriched Uranium (HALEU) nitride fuel. Based on the Westinghouse Lead-cooled Fast Reactor, the reactor can achieve and maintain criticality using natural uranium as feed fuel for a refueling interval of 1050 EFPD. Analysis indicates an equilibrium discharge burnup of ∼ 230 MWd/kgHM . The refueling strategy gradually replaces HALEU fuel with natural uranium assemblies, ensuring stable power profiles during the transition cycles. The reactivity control system can insert at least ∼ 15 $ negative reactivity. Thermohydraulic assessments confirm effective heat removal, with peak fuel temperatures within operational limits. The study addresses proliferation risks from weapons-grade plutonium generation by proposing strategies for fuel reutilization and fuel assembly optimization. The study confirms the feasibility of the start-up core to sustain the RFBB mode while suggesting the potential for further optimization to control excess reactivity and enhance proliferation resistance. • A HALEU start-up core was developed to support the RFBB concept. • A novel approach to loading a fast reactor with natural uranium was investigated. • Shows the theoretical feasibility of a burning wave in a nitride-fueled LFR. • Highlights potential for enhanced fuel utilization and reduced waste.