Development For Three-dimensional Discrete Ordinates Neutron/Photon Transport Code

Needing more accurate results in shielding calculations, existing codes can not fully meet the demand. So some aspects need to be taken into consideration, such as, improving computational accuracy and economics of nuclear power station, diminishing the convention in design availably, mastering the core technique in shielding calculation. Based on extensive research and practical applications, Neutron Transport Theory and Numerical Methods was analyzed in this paper through the deterministic method. And a program, CTDOS, was developed to solve three-dimensional Cartesian coordinate system under steady-state neutron/photon transport equation. This program mainly used for nuclear radiation shielding calculation as well as for a nuclear device design analysis.Determination method is one of the main reactor physics analysis soft wares due to its fast calculation, high accuracy, and powerful capability to treat deep-penetration shielding problem. Discrete ordinate method as one of determination method is widely used in the field of nuclear engineering. According to SN method, this thesis, using the processing method of group-dividing approximate method for energy variables; space variable for finite difference approximate discrete and direction variable for Discrete ordinates (SN), obtained discrete differential forms of the three-dimensional transport equation. In view of the complexity of the neutron/photonic transport equation, the source iterative method was used for solving in addition to some special circumstances which are difficult to solve by analytic method. Based on these method, CTDOS program was explored.In this paper,the code CTDOS is tested by two benchmarks, Takeda benchmarks and Kobayashi benchmarks. The results showed that algorithm and the corresponding programme codes is correct, the "fixed-source problem" and the fission multiplication factor,"Keff",are preliminarily performed, giving successfully neutron/photon flux density distributions at mesh points. In the view of a better calculation economy and stability,and of its universality, the program needs future perfection about several aspects listed at the end of the paper.