Effect of non-uniform inflow on the internal flow and hydrodynamic characteristics of a small modular reactor coolant pump

Abstract

Small reactors have broad application prospects due to their advantages of safety, economy, and portability. In the first circuit of a small reactor nuclear power plant, the steam generator is directly connected to a reactor coolant pump, and there is a non-uniform flow situation, which has not been studied. Taking the small modular reactor coolant pump as the research object, the influence of non-uniform inflow on the internal flow and hydrodynamic characteristics of the small modular reactor coolant pump was investigated using CFD numerical simulation methods, and was verified by experiment. Firstly, the basic structural parameters of key hydraulic components are determined based on the design input parameters, and the initial model of the impeller and diffuser of the small modular reactor coolant pump is modeled. The channel-head, impeller, diffuser, and casing are modeled using three-dimensional software; Secondly, the hydrodynamic performance of the small modular reactor coolant pump was experimented, and the experimental results verified the reliability of the numerical simulation; After comparing the external characteristics of the straight-pipe small modular reactor coolant pump coupling model and channel-head small modular reactor coolant pump coupling model, it was found that the head and efficiency of the straight-pipe model were better than channel-head model, indicating that non-uniform inflow had a certain impact on the performance of the small modular reactor coolant pump. Finally, the internal flow states of the straight-pipe model and the channel-head model were compared and analyzed from the perspectives of pump internal flow field, pump internal velocity and pressure distribution. The results showed that the sudden contraction of the direct connection between the channel-head and the small modular reactor coolant pump and the short length of the direct connection caused the inlet flow of the pump to be non-uniform, which adversely affected the hydrodynamic and internal flow characteristics of the pump. This study provides a certain idea for the research on the suppression of non-uniform inflow from small modular reactor coolant pumps and the improvement of non-uniform inflow from small modular reactor coolant pumps.