This paper is aimed at analyzing the structural responses of a Generation IV heavy-liquid-metal-cooled reactor (lead-bismuth-cooled fast reactor) vessel in the event of earthquake. For a seismic design, the seismic time history response analyses are carried out for both a top support type and a bottom support type. It is found that the bottom support type exhibits the better performance. There is the gap between the reactor vessel and guard vessel being filled with  argon. It is indispensable to add bellows at vessel upper end for a bottom support type to achieve the connection and seal between the reactor vessel and guard vessel. This paper is the first attempt to evaluate the effects on structural seismic performance by adopting the equivalent springs to simulate this elastic connection.
For a seismic investigation, there is a key issue that should be focused on, namely: the fluid-structure interaction due to seismic loading. The vessel is filled with a high-density fluid and might lead to severe hydrodynamic pressure significantly in the occurrence of earthquake. It will impair the structural integrity of reactor vessel. In order to study the structure effects of reactor vessel under seismic loading, an appropriate 3-D finite element analysis model has to be set up and the FEM code ANSYS has been implemented.