An assessment of LMR reactor core vertical acceleration under seismic events

An important concern in Liquid Metal Reactor (LMR) design is the maximum vertical acceleration of the reactor core during seismic events. If the vertical accelerations at the reactor core exceed gravitational acceleration, the subassemblies may lift off, thus losing hydraulic holddown. This paper presents an assessment of reactor core vertical accelerations for large-diameter LMR reactors under various core-support conditions. A review of the various types of core-support concepts in use for LMR plants is contained in Section 2. In Section 3, the vertical seismic response is determined for a pool-type reactor with a core supported by the reactor vessel bottom head. Section 4 deals with the vertical core seismic response of a LMR with a core supported by the side wall of the reactor vessel. Conclusions and design recommendations are given in Section 5. (orig./GL)