Actually, series of studies on the flow and heat transfer characteristics in the reactor pressurized vessel (RPV) of PWR could be found. Xu et al. [
5–
7] performed series of detailed CFD simulations on flow features in the lower plenum of the typical PWRs using the
Code_Saturne, which is free, open-source software developed and released by EDF. Some meaningful conclusions could be used for future structure design and optimization of flow diffusers. Philippe et al. [
8] built the 1/5 scale Rossendorf coolant mixing (ROCOM) experimental facility based on the upper plenum of European pressurized water reactor (EPR), which includes all the SCs, CRGTs, and internal control components. The experimental results show that, at the core outlet, the flowrates in FAs near the four hot legs are significantly higher than the average value mainly due to the hot leg suction effect, while the flowrates in FAs in the core central region are lower. The CRGTs greatly affect the flowrates of the FAs and the flowrates in the FAs with CRGTs are significantly higher than those without CRGTs. Xu et al. [
9] compared the transverse flow strength at the core outlet of AP1000 with other types of Westinghouse reactors using CFD software. The simulation results show that the coolant transverse velocity in the reactor core increases along the height direction and the maximum coolant horizontal velocity is not higher than 1/10 of the axial velocity.