Research of the few-group cross-sections calculation based on the software package MOSASAUR

To further enhance physical design calculation capabilities of fast reactor cores and improve the applicability of traditional few-group cross-section calculation methods for complex geometries, research on few-group cross-section calculation methods has been conducted based on the MOSASAUR fast reactor core physics calculation software package. Building upon the existing zero-dimensional and one-dimensional models, a two-dimensional calculation method based on the subgroup method and method of characteristics (MOC) has been developed. A multi-group library has been built suitable for the subgroup method and the capability for precise geometric modeling of assemblies has been established. Resonance self-shielding is processed using the subgroup method and transport calculation is performed using a GPU-accelerated MOC. Verification and validation have been conducted at both the assembly and core levels. For assembly calculations, three typical fuel assemblies and two complex fuel assemblies were used to compare different few-group calculation methods. For core calculations, the MET-1000 and MOX-1000 benchmark problems were used. Numerical results show that the newly developed two-dimensional few-group cross-section calculation method has good computational accuracy, especially for problems with complex assembly structures, where it demonstrates a significant advantage in computational precision.