Experimental and CFD Simulation of the RPV Head Plenum

This paper aims to investigate the flow characteristics of the RPV Head Plenum region in the HPR1000 Pressurized Water Reactor (PWR) to provide support for addressing the erosion of the Thermal Sleeve in operational CPR1000 PWR plants and optimizing the RPV Head Plenum region structures in HPR1000 PWR plants. This paper uses Computational Fluid Dynamics (CFD) methods to conduct numerical simulations of the RPV Head Plenum region and also carries out hydraulic model experiments of the RPV Head Plenum to obtain the flow distribution and hydraulic characteristics of key areas within the RPV Head Plenum region. The theoretical analysis and experimental results show that: The CFD results of the key areas in the RPV Head Plenum and the measured lateral velocity deviations from the experiments are within 10%. Under normal operating conditions, the overall flow velocity within the RPV Head Plenum is relatively low, but higher velocities are observed near the RPV Head nozzles and nearby surface. The coolant water in RPV Head Plenum flows downward through the holes at the top of CRGT and then flows into the Upper Plenum, which is consistent with the expectation of the HPR1000 “Cold RPV head”. Additionally, a vortex with higher flow velocity is present near the Thermal Sleeve Bell Mouth in the central region than in the peripheral area of the RPV Head Plenum, resulting in more severe fluid impact and wear on the thermal sleeves.