Influence mechanism of the non-uniform inflow on performance of reactor coolant pump

Abstract

In Advanced Passive (AP) series reactors, the reactor coolant pump (RCP) is directly connected to the bottom of the steam generator (SG) rather than a longer pipe for the fully development of inflow, which leads to the unsteady vortex at pump inlet. Thus, this type of inflow is called non-uniform inflow and might cause extra hydraulic loss. The method for analyzing hydraulic loss is by evaluating pressure drop, which cannot determine the exact locations of the loss occurred. In this study, experimental and numerical approach is employed to analyze the influence mechanism of non-uniform flow on performance of RCP. The power loss theory is adopted to investigate flow state and location of losses generated under different inflow conditions. The result shows that the non-uniform inflow causes the loss of total head increase inside the RCP. The total loss of head in the impeller and diffuser increased about 17% and 32% respectively. Then, the power loss integrated in hydraulic domain shows that the most important reason for hydraulic loss is the net decrease of mean kinetic energy, especially in non-uniform flow. For the local power loss, the change in distribution caused by kinetic energy also varies significantly. Depending on the loss mechanism inside the pump, it suggests a broad range of promising applications in hydraulic optimization of the RCP.