Experimental studies on seismic vibration phenomena of FBR core components

This paper deals with vibration behaviours in a cluster of components with hexagonal cross-section in a limited area under dynamic excitation due to seismic events. A seismic analysis of the Fast Breeder Reactor Core is a complicated problem, which includes the dynamic interaction with many components of different vibrational behaviours. The core components are assumed to be elastic beams fixed at the lower part and free as the top. They have first mode resonant frequenceis in the same components as earthquake wave predominant frequencies and are arranged in the barrel with small gaps between them. When strong earthquake excitation is applied to the barrel, the cluster of components displace to geometrical limits in the barrel and collisions will occur between adjacent components as a result of their relative motion, because of the small gaps between components. For these reasons, a non-linear analysis with components collision is necessary to predict the seismic response in the cluster of components. It is hoped to establish a relatively simple calculation model with lower degrees of freedom within the range where the phenomena cannot be mistaken. In order to clarify the complicated seismic response of components, experiments were carried out under two situations. Single row components tests and grouped components tests were carried out in a fluid region with actual components. (orig./RW)