For high earthquake resistance and ease of installation, free standing racks which are not anchored to the pool floor or walls has been adopted in many countries.
Under the earthquake, the response of the free standing rack is highly nonlinear and involves a complex combination of motions (sliding, rocking, twisting, and turning) and impacts between the fuel assemblies and the fuel cell walls, rack-to-rack, and the pit floor and rack pedestals. To obtain an accurate simulation of the free standing rack, the seismic analysis requires careful considerations of these complex phenomena (sliding, rocking, twisting, and turning), fluid coupling effects and frictional effects.
We carried out seismic experiments on the full-scale rack model in water and dry conditions to obtain the fundamental data about free standing rack (sliding, rocking and turning motions). We have developed the nonlinear dynamic analysis method to predict seismic response for the free standing rack utilizing the full-scale test result and verified the analysis evaluation method of the rack by comparison of test result.