Investigation on sloshing and vibration mitigation of water storage tank of AP1000

AP1000 is a standard design developed by Westinghouse for an advanced generation III+ nuclear power plant (NPP) utilizing passive features. Water storage tank of AP1000 plays an important role in cooling down the temperature of the inside of the NPP. However, the water sloshing of the water tank may have significant effects on the seismic performance of the NPP when the structure is subjected to earthquake. The purpose of the present study is to numerically investigate the influence of fluid-structure interaction (FSI) on the dynamic behavior of water tank and effects of water sloshing in reducing seismic response of the shield building. For that purpose, a FSI algorithm of finite element technique is employed for the seismic analysis of water storage tank for AP1000. To evaluate the positive effect of FSI during the process of reducing seismic response, six cases of water height have been studied and also compared with that of the empty water tank. The Arbitrary Lagrangian Eulerian (ALE) algorithm is used to simulate the fluid sloshing and oscillation of water tank under a typical earthquake occurred at NPP. Furthermore, comparison is performed among parameters obtained from simulation for various heights of water and oscillation frequencies, with respect to seismic response and fluid surface. The results clearly show that the water level height has an important influence on the dynamic response of nuclear power plant (NPP), but case 3 of water level can effectively mitigate seismic response and sloshing oscillations of the structure, which can improve the design of seismic performance for AP1000 or CAP1400 in future.