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 (DFRm) 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 keff 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.