Experimental study on seismic sloshing of storage water for spent fuel pool in NPPs

• Development of evaluation methods and procedures for the volume of water splashed out of the spent fuel pool in NPPs. • Considering multiple splashes and the increase in freeboard in the estimation of water splash volume. • Estimation of water splash volume under 1D and 2D excitations. • Single-degree-of-freedom approach for water sloshing height. Due to the event of Fukushima Daiichi Nuclear Power Plant in 2011, the U.S. Nuclear Regulatory Commission (NRC) requested all U.S. nuclear power plants to conduct seismic hazard re-evaluation per the newest guidance and requirements. Among them, the spent fuel pool (SFP) is considered an important facility. The related evaluation guidance provided in the Electric Power Research Institute EPRI-1025287 report emphasizes failure modes of the SFP that could result in “rapid drain-down”. One of the possible causes is the volume of water splashed out of the pool due to seismic sloshing. In EPRI-1025287 report, a very convenient yet conservative approach for estimating water splash volume was provided. To obtain more accurate results, this study employed a shaking table test of liquid storage tanks to develop a more realistic water splash volume estimation method, based on the relationship between seismic-induced sloshing height and the associated total volume of water splashed out of the tanks. In the development of this method, the use of a single-degree-of-freedom (SDOF) systems to estimate the sloshing time history is also proposed for subsequent splashed volume calculation. Furthermore, the sloshing frequency, which is related to the sloshing height and the splashed water volume, is also a key focus of the study.