Coolant distribution and mixing at the core inlet of PWR in a real geometry

The flow distribution and mixing at the core inlet are very important to determine the cooling ability of the fuel assemblies. This paper focused on a real geometry model of PWR. The downcomer and the lower plenum are described in detail. A combination of structured and unstructured grids was applied in different regions. The core part is simulated by a distributed resistance model. A detailed flow distribution of core inlet and the volume fraction of two inlet loops are obtained. The results show that the application of the CFD technology in the reactor thermal-hydraulic analysis is feasible. The results are very sensitive to the placement of the interface between different parts of grids. Some conclusions on the applicability of CFD for turbulent distribution and mixing problems in core were drawn. Some recommendations on CFD modeling were also proposed in this paper. The results show the accuracy of CFD method, and the suitability of applying CFD methods in engineering applications for turbulent mixing in nuclear reactors is concluded.