CFD Simulation and Experiment on Sloshing Phenomena in Spent Fuel Pool under Seismic Excitation

This paper presents the investigation and calculation of the maximum sloshing height of water inside the spent fuel pool (SFP), the spent fuel racks (SFR) are kept in partially filled SFP. Under the seismic condition, the sloshing of the free water surface in the pool can cause overflow. For the safety assessment, it is necessary to know the maximum sloshing height of the water. It is difficult to predict the nonlinear sloshing phenomenon of the water, when it's occur. In this investigation and calculation, The Computational Fluid Dynamic (CFD) is used for simulation under seismic excitation; the Volume of fluid (VOF) model were applied to get an accurate outcome of water free surface displacement in the SFP, three different excitation frequency (three cases) were applied. A model of the SFP and SFR are designed for validation. The comparison of the maximum water free surface displacement result of the SFP showed the difference between CFD and experiment for case one (natural frequency) with SFR for left and right walls are 0.641, 1.666mm respectively, for the natural frequency without SFR the results showed that the sloshing load is stronger, higher amplitude and over flow is observed, for the case two (3.577Hz) the maximum difference for left and right wall with SFR is 0.52,0.362mm respectively, and without SFR 1.666, 0.646mm respectively, for the case three (10.731Hz) the maximum difference for left and right wall without SFR is 1.148, 0.828mm respectively, at the begging of excitation of non- resonant frequency between the first and second mode(10.731Hz), the water sloshing start rising and gradually declined. From above comparison the CFD simulation results is accepted to predict the maximum sloshing is the SFP. SFR can suppress the sloshing effectively and sufficiently reduce the water sloshing as well.