In prototype fast breeder reactor (PFBR), the spent subassemblies (SA) are taken out of the reactor during refuelling are stored in spent fuel storage racks. These racks of are immersed in a pool of water in spend subassembly storage bay in the fuel building. Guide plates are provided at three elevations in the racks, to keep the subassemblies in position and to maintain the gap between the subassemblies. Structural integrity of the subassemblies along with the storage racks needs to be ensured under all design basis events including earthquakes. In addition to the global responses of the storage racks and subassemblies during seismic excitation, the stresses developed in the subassemblies due to rattling of these assemblies with the guides in the intermediate plates is a concern which needs to be addressed. The objective of the present study is to quantify, the effect of rattling of subassemblies in the storage rack during seismic excitations. Storage rack is considered to be in fully filled condition and the response of the rack along with subassemblies is analyzed using spectrum compatible time histories for operating basis earthquake (OBE) and safe shutdown earthquakes (SSE). The impact forces extracted from the analyses is imposed on a detailed shell model of the subassembly, and dynamic stresses developed in the subassembly is analyzed. Analyses indicate that, the effect of seismic induced rattling is slightly dominant in the fuel subassemblies located in the central portion of the rack compared to the subassembly at the corner of the rack. The stress intensities in the subassemblies are found to be well within the acceptable limits for OBE and SSE conditions.
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