Improved core design and integrated back-end fuel cycle scheme for 200 MWt marine molten chloride fast reactor

This study presents an improved core design and the introduction of integrated back-end fuel cycle scheme for a 200 MWt Molten Chloride Fast Reactor (MCFR) intended as nuclear marine propulsion. The objective is to increase fuel burnup and reducing uranium consumption whilst maintaining appropriate safety level. Dual Reflector concept was introduced to increase fuel burnup, by using outer secondary magnesium oxide reflector as an addition to primary beryllium oxide reflector. To increase nuclear fuel utilisation, Partial Fuel Change (PFC) mechanism was applied with several fuel replacement fractions, whilst uranium re-enrichment scenario was inserted within the refuelling scheme to minimise natural uranium consumption even further. All burnup calculations were conducted using Serpent-2 reactor physics code and ENDF/B-VII.0 neutron cross section library. From the findings, the use of Dual Reflector concept with 50% PFC fraction and uranium re-enrichment increased fuel burnup up to 150.89 GWd/tHM and operational time up to 29 years. The use of Dual Reflector yields slightly weaker temperature coefficient of reactivity (TCR), but still sufficiently negative nonetheless. Overall, Dual Reflector concept with PFC refuelling scheme and uranium re-enrichment is suitable to improve design and fuel cycle performance of the marine MCFR. Whilst PFC scheme offers only a modest improvement of fuel consumption, uranium re-enrichment allows a significant reduction of natural uranium and enrichment demands.