Abstract: Primary Neutron source provides sufficient initial neutron flux for reactor before criticality, which is a necessary condition for the first start-up of PWR. The measured surface dose rate of neutron source shielding container of a third-generation PWR is relatively high, which could affect the safety of personnel and equipment to a certain extent. In order to reduce the radiation level, Monte Carlo method is used to establish a model for calculation, to evaluate the performance of the neutron source shielding container, and to propose an improvement plan for the shielding container in combination with neutron energy spectrum analysis. It is expected to reduce radiation levels by 99.5% while ensuring only a small increase in volume and satisfying transportation performance.

Key words: Third-generation pressurized water reactor, Primary Neutron source (PNS), Radiation protection, Monte Carlo, optimization