The composition optimization of rare-earth doped 316L stainless steel on thermal neutron shielding

The miniaturization of reactors requires the shielding of neutrons in a short distance, which puts forward higher requirements on the performance of shielding materials. Considering that rare earth elements, such as Gd, Sm and Eu, have extremely high thermal neutron absorption performance, the absorption characteristics of different single- or multi-rare-earth-doped 316L stainless steels (0.5–5 wt%) were investigated by performing neutron shielding calculation. Calculations show that, for the thermal neutrons (especially for hardened ones) with a shielding target of 99 %, the multi-doped material requires a smaller shielding thickness than the single-doped ones and has theoretically better neutron absorption performance. This study proposes a composition design method for thermal neutron shielding material which is foreseen to be used in research and development of small and lightweight reactors.