Numerical simulation of dynamic response of nuclear island under seismic load

As clean energy, nuclear power has shown broad prospects for development, so it is of great importance to investigate response of nuclear power plant under seismic loading. Firstly, finite element model of the AP1000 nuclear island is built to perform modal analysis for obtaining vibration modes of nuclear island. Then, by using infinite element to simulate the far field ground and finite element to characterize the near field ground, the seismic responses of nuclear island on different ground conditions are studied with the foundation embedment and soil-structure interaction effect considered. Results show that as foundation stiffness becomes larger, the response acceleration of nuclear island increases, while the period corresponding to peak spectral acceleration of nuclear island decreases. At the same time, the node stress of nuclear island increases but its relative displacement reduces. By considering soil-structure interaction, peak value of response acceleration of soft foundation diminishes while the period corresponding to peak spectral acceleration of foundation rises, which implies that soil-structure interaction has significant influence on seismic input of nuclear island on the soft ground. For hard rock foundation, the influence of soil-structure interaction on seismic input can be ignored.