Study Of Steam Generator Channel Head On The Performance Of Reactor Coolant Pump

In order to handle the global energy shortage, China has introduced the third generation of advanced pressurized water reactor technology AP1000 which has not been in engineering application. In comparison with other reactors, two parallel AP1000 reactor coolant pumps(RCPs) are invertedly welded to the channel head of steam generator(SG). For this unique design, the coupling effect between RCP and SG must be fully evaluated. Through modeling integrally the channel head of SG and RCP, the above coupling models were simulated by CFD method and the influence of SG channel head on RCP inflow field, hydraulic performance and hydrodynamic performance were studied.Firstly, the fluid domains and grids of steam generator channel head and reactor coolant pump were generated. The suitable grid number was determined by grid independence verification. On steady simulation, the numerical calculation of scaled RCP was verified by experiments. It turned out that the numerical calculation and experiment results had a good agreement. On transient simulation, the time step size independence was verified, and the time which was required for RCP impeller to rotate one degree was ultimately determined as the time step size.Secondly, flux distribution simulation of SG channel head near hot leg pipe and co-simulation of RCP and SG channel head near cold leg pipe were finished. The results showed that inflow distortion was generated at RCP inlet because of the uneven flux distribution of U-tubes, the disordered flow field in the region of SG channel head near cold leg pipe and the intersecting area between SG channel head and RCP. As a result of RCP inflow distortion, local low-pressure areas were generated at RCP inlet and the fluid velocity at impeller inlet was different which aggravated the pressure fluctuations of RCP inlet and the juncture between impeller and guide vane.Thirdly, the influence of inflow distortion on RCP hydraulic and hydrodynamic performances was analyzed. It was found that the inflow distortion reduced RCP head and efficiency and the decrease degree increased with the flux. On the aspect of impeller axial forces, the average of axial forces was slightly reduced, but the fluctuation increased because of RCP inflow distortion. On the aspect of impeller radial forces, the average and fluctuation increased greatly on account of RCP inflow distortion.Finally, a conical baffle plate structure on the RCP inlet pipe was put forward. Through the comparison of different conical baffle plates which had three openings, four openings, five openings and six openings respectively, it was found that three openings’conical baffle plate could improve RCP inflow condition and the flow resistance was relatively smaller. After that, according to the method of orthogonal experiment, optimization design was carried out on the three openings’ baffle plate. All of the results above can provide references for the safe operation of RCP and the optimization design of RCP inlet pipe.