Study on Selection Method of Shielding Nuclides in Nuclear Reactor Based on Non-Dominated Sorting

In the reactor, the main purpose of radial shielding was to protect the internal structure and staff from radiation damage. The good shielding material must have both a high elastic scattering cross-section and a high absorption cross-section to reduce the radiation level outside the reactor core and ensure the safety of workers and equipment outside the reactor. In this paper, a new type selection scheme of shielding material was proposed, which read the reaction cross-sections of all-natural stable nuclides in the ENDF/B-VII database, calculated the single group cross-sections of various reactions of all nuclides by the integral method according to the neutron energy spectrum. Then ranked the nuclides with different cross-sections as the target, to screen the nuclides with the best neutron and photon shielding effect. In this paper, a typical Monte Carlo particle transport program was used for preliminary verification, which was applied to the energy spectrum of the pressurized water reactor and sodium-cooled fast reactor. The results show that for neutron shielding, photon shielding, and neutron-photon shielding, in the thermal neutron spectrum, the coincidence rates between the non-dominated sorting scheme and the Monte Carlo method were 95 %, 98.95 %, and 94.87 % respectively, and in the fast neutron spectrum, the coincidence rates between the non-dominated sorting scheme and the Monte Carlo method were 72.5 %, 95.79 %, and 82.5 % respectively. The calculation time of non-dominated sorting was less than 3% of that of the Monte Carlo method. It provided an efficient method for the selection of shielding nuclides in advanced reactors and had engineering application significance.