In order to investigate the influence of guide vane structure on hydraulic performance of reactor coolant pump (RCP) under coastdown condition, the guide vane structure was modified to form staggered guide vane by adding splitter plates that staggered flow channel across two layers. Numerical methods were used to compare the hydraulic performance characteristics of staggered guide vane and original guide vane in RCP. From the results, the external characteristics of RCP slightly decreased by staggered guide vane under coastdown condition. As the coastdown flow rate decreased, the difference in head and distribution of turbulent kinetic energy between two models diminished. The static pressure at impeller outlet and volute tongue increased by staggered guide vane, while distribution of high pressure inside guide vane of original model changed under coastdown condition. The area of high turbulent kinetic energy expanded due to staggered guide vane, which then became smaller after reaching the half-flow point. The pressure load on impeller blade increased by staggered guide vane, and the pressure load at impeller blade outlet was always lower than that of original guide vane. The minimum pressure appeared near the inlet of impeller, while the maximum pressure appeared near the streamline with a chord length of 0.8. Furthermore, vortex rope in outlet of staggered guide vane and outlet pipe of volute is smaller than that of original guide vane scheme.


