Scaled pool and storage rack model experiment for simulating severe earthquake accidents with equivalent similarity

The spent fuel and storage racks are susceptible to slides and can impact each other in the spent fuel pool due to the seismic base excitation that compromises their seismic safety. In addition, a strong earthquake can lead to the overflow of contaminated water and pressure loads to the storage pool by sloshing. These issues have been highlighted in recent years in nuclear regulations and industries, as the magnitude and frequency of earthquakes has increased in Korean peninsula. To satisfy the growing needs of estimating realistic spent fuel assembly dynamics and to assess the seismic safety of the real spent fuel pool, a reliable prediction model should consider the sloshing of the water surface and fluid-structure interactions between the racks, plus fuel and water, in the deep end of the pool. In this respect, the joint experimental test program on the scaled model and analysis model development project were funded by the Korean government. A scaled pool model with simplified racks, that were submerged in the filled pool, was mounted on the hydraulic shaking table and excited by a frequency-variated sinusoidal force to simulate typical dynamic events and earthquake accidents. According to the excitation condition and level of water, the amount of overflow, dynamic pressures on the wall, the sloshing wave profiles of the free surface were measured and compared with the analysis results. The residual response of the internal submerged structures, measured by accelerometers, showed natural sloshing modes of vibration for the filled water. The test results will show the validity of the numerical model for the seismic safety evaluation of the spent fuel and be used to predict full scale pool behaviours.