A new coupling method based on MOC and the SN nodal method for the neutron transport calculations

The ray spacing must be fine enough to traverse every region of the reactor to get accurate results when using the method of characteristics. However, when calculating some research reactors, the active zone is relatively small compared to the entire problem. It would be time-consuming and memory costing to apply MOC for the entire geometry. A new approach that couples MOC and the SN nodal method is proposed and implemented to solve those issues. The calculation region is divided into the MOC domain, which includes active zone or complex structures, and the SN domain, such as the moderator and reflector region. The MOC and SN nodal methods are coupled by the interface angular flux. The 2D C5G7 benchmark and a 2D JRR-3 plate-type fuels reactor problem are tested to demonstrate the accuracy and efficiency of the coupling method, and the numerical results show that the coupling method achieves superior efficiency.