Direct 3D MOC for whole-core transport calculation

Due to the need for high accuracy and more complex core geometry, whole-core transport calculations with the MOC are demanded. Recently, a 2D+1D method has been proposed to perform 3D whole-core transport calculations, but it is not easy to apply this method to the cases with complex geometry in the axial direction. Direct 3D MOC calculations are thus required. This approach is however limited by the amount of computer memory which is required for the ray tracing data that is required by the MOC. This paper presents a modular tracing technique and corresponding angular quadrature sets, which can greatly reduce the amount of ray tracing information, making it practical for the MOC to deal with the large 3D problems. In this paper, we introduce the model of the modular ray tracing technique and give some results of our method.