Study on Primary Shielding Calculation Based on PWR Power Plant

The primary shielding calculation based on 3D PIN-BY-PIN power distribution of the whole reactor core is one of the most important and difficult problems for the radiation shielding design of a nuclear power plant, and it is a typical deep penetration problem with complex source and geometry. Using the three-dimensional Monte Carlo code and two-dimensional Discrete Ordinate code DORT, this paper performs a detailed comparison of the primary shielding design results of AP1000. To solve the deep penetration problem of the Monte Carlo code, and to obtain reliable results, the surface source bootstrapping calculation function of the Monte Carlo code is studied. Numerical results demonstrate that the surface source bootstrapping calculation function of the Monte Carlo code is a very effective method to solve the deep penetration problem. And the comparison results indicate that distributions of fast neutron, middle-range energy neutron and gamma ray agree well. But the result of thermal neutron calculated by DORT is smaller than that of the Monte Carlo code, especially in primary concrete shield wall. The difference between the results of the above two methods mainly comes from the difference of the cross-section libraries. The surface source bootstrapping calculation method of the Monte Carlo code and the conclusion of AP1000 primary shielding are valuable for the practical nuclear power project.