Neutronic performance analysis of U–Mn fuel and MgO-BeO tube material in the dual fluid reactor

This study investigates the feasibility of using a Uranium–Manganese (U–Mn) alloy as an alternative fuel for the Dual Fluid Reactor (DFR m ) concept to increase the temperature margin, along with a Magnesium Oxide–Beryllium Oxide (MgO–BeO) ceramic fuel tube. Neutronic analyses were performed using the SERPENT 1.1.7 Monte Carlo code with the ENDF/B-VII cross-section library to evaluate fuel performance, reactivity behavior, and safety margins. The results indicate that the U–Mn fuel exhibits lower k e f f values and shorter fuel cycle length to those of the U–Cr fuel, while providing the advantage of a lower eutectic temperature. Reactivity coefficients found to be negative for both fuel and coolant with the SiC fuel tube, ensuring inherent safety during temperature excursions. However, for the MgO–BeO configuration, the reactivity coefficients for MgO-BeO were found to be positive, which represents a critical drawback of this material; hence, further geometrical optimization is required. Consequently, although U–Mn fuel maintains negative temperature feedback under SiC-based configurations, alternative tube materials such as MgO–BeO require further optimization to ensure stable and inherently safe reactivity behavior throughout the fuel cycle. Future research could focus on optimizing reactor geometry to enhance the utilization potential of U–Mn fuel.