The Powerful MOC Module in Advanced Neutronics Lattice Code GALAXY

Due to powerful geometry treatment capability, Method Of Characteristics (MOC) becomes the most popular method to solve neutron transport equation. However, boundary conditions always restrict the MOC method’s widely application. Most of the current neutronics lattice codes based on MOC can only be used to solve one or two specific geometrical shapes. In this paper, we developed a powerful MOC module, which can treat different geometrical shapes with two methods. For special geometrical shapes, such as rectangle, 1/8 of square, hexagon, 1/3 of hexagon, 1/6 of hexagon, the MOC module adopts special trajectory layout and angle quadrature set, which can reduce the computation time. For other general geometrical shapes, the MOC module use ray prolongation method, which can treat arbitrary geometry shapes and boundary conditions but need much computation time. This MOC module was incorporated into advanced neutronics lattice code GALAXY, which developed by Nuclear Power Institute of China. The numerical results show that the GALAXY code can be used to calculate 2D neutronics problems with rectangle, hexagon, and other complicated geometry shapes accurately. In future, the GALAXY code will gradually become the main neutroncis lattice code in NPIC.