Dynamic response analysis of a spent-fuel dry storage cask under vertical drop accident

This work presents a study on dynamic responses of a spent-fuel dry storage cask, recently developed in Taiwan INER, under vertical drop accident. Three casks with size proportion of 1:1, 1:1/2.5, and 1:1/5 are respectively simulated to explore the size effect in small scale drop tests. The analysis is carried out by fully 3-D simulation following the procedures of explicit finite element. The commercial code, LS-DYNA is employed to treat the strong nonlinear phenomena, such as the geometric, material and contact/impact nonlinearities. In addition, a technique for quickly determining the adequate cut-off frequency in post-process of acceleration response curve is proposed. The height of the vertical drop event is 61 cm, which is adopted in accordance with the operation procedures designed for a nuclear power plant in Taiwan. The scenarios of 0° straight impact and 5° oblique impact are both investigated. The discrepancies in the straight and oblique impacts and in the three diverse size scales are reported and discussed. It is shown that to predict the response of 1:1 prototype only using small scale test is nearly impossible. Numerical simulation is a must to help predict the response of 1:1 prototype.

► We investigate the size effect in vertical drop test of a dry storage cask using explicit finite element simulation.
► A procedure to quickly and reasonably determine cut-off frequency for acceleration response curve filtering is proposed.
► We point out that using small scale test to predict 1:1 prototype test is nearly impossible.
► Numerical simulation is a must to help predict the response of 1:1 prototype.