Study on the application of three-dimensional discrete ordinate method in the high precision shielding calculations of nuclear reactor

As the development of computing capacity,three-dimensional discrete ordinate (S_N) method has become one of the main approaches of the nuclear reactor shielding calculation. This paper focuses on the key issues of the application of three-dimensional S_N method in the reactor shielding calculation, including: the detailed geometry modeling approaches, the accurate specification of the core source, and the sensitivity analysis of the nuclear reaction cross sections. Moreover, a typical pressurized water reactor have been detailed modeled, the fast neutron flux on the inner surface of the reactor pressure vessel have been simulated. The results have been compared with the results of Monte Carlo methods, which show the high accuracy, effectiveness and correctness of three-dimensional S_N method. (authors)