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Neutronics comparative analysis of fuel assemblies using CSG and DAGMC methods


 The traditional Monte Carlo method uses the Constructed Solid Geometry (CSG) method to build up the geometry by creating surfaces and using Boolean operators. This method has obvious deficiencies for new type reactors with complex geometry and large size. This method has the problem of geometric overlap. Direct Acceleration Geometry Monte Carlo (DAGMC) method based on CAD geometry modeling can accurately describe higher-order surfaces, which can effectively overcomes the shortcomings of CSG modeling method and effectively build up the model. Additionally, CAD geometry has good visual effect. On the one hand, it is conducive to the verification of the correctness of the model. On the other hand, it is beneficial to the analysis of the calculation results DAG-RMC function based on Reactor Monte Carlo code RMC can directly use CAD model to carry out particle transport calculation. Based on CSG and DAGMC, this paper constructed three dimensional rod repeat structure fuel and plate type repeat structure fuel assemblies respectively and calculated keff as well as power distributions in order to verify the correctness of DAGMC in particle transport and critical calculation for complex geometry. Through comparisons, the keff and power distributions calculated by the two methods are in good agreement, verifying the correctness of DAG-RMC function.