Effect of fluid-structure interactions on seismic response analysis

The thickness of LMR(Liquid Metal Reactor) structures operating at high temperature are very thin compared with conventional PWR to reduce the thermal stress. Therfore, it is necessary to develop the simple seismic analysis model including the fluid-structure interaction effects. In this paper, the seismic analysis code, SAC-THA including the fluid-structure interaction modeling for the immersed concentric cylinders are developed and the vibration and seismic response characteristics are investigated for the simple immersed concentric cylinder. From the coupled modal analysis and the seismic analysis, it is verified that the fluid added mass significantly affect the vibration characteristics and the seismic responses. Therefore the fluid coupled effects should be carefully considered in seismic response analysis of the immersed concentric cylinders