Neutronic Performance of Reflector Materials in Lead-Cooled Fast Reactor

This study evaluates the neutronic performance of 12 reflector materials (Ba2Pb, BeO, graphite, lead, magnesium, MgO, PbO, PbS, SiC, Zr3Si2, ZrC, and Yttria-Stabilized Zirconia) in a Lead-cooled Fast Reactor (LFR), using OpenMC with the ENDF/B-VIII.0 nuclear data library. The materials are assessed for their impact on effective multiplication factor (keff), neutron leakage, neutron flux and fission rate distributions, burnup, and activation products. BeO exhibits superior performance, achieving the highest effective multiplication factor, lowest neutron leakage, and longest fuel cycle length due to its low capture cross-section and high (n, 2n) reaction rate. Other materials, such as MgO and graphite, also perform strongly, while in contrast, materials like Ba2Pb and lead show higher leakage and non-uniform flux distributions, limiting their suitability. BeO results in the highest minor actinide activity, whereas Ba2Pb yields the lowest. These findings address a key gap in LFR reflector performance, positioning BeO, followed by MgO and graphite, as top candidates for optimizing neutron economy and reactor efficiency.