Predicting the Response of the Impact Limiter in the HI-STAR Family of Transport Packages Using a Benchmarked LS-DYNA Dynamic Model

HI-STAR spent fuel transport casks are protected by AL-STAR impact limiters against excessive impact loads under the hypothetical 9-m drop condition postulated in 10CFR71. The aluminum honeycomb is used as the energy-absorbing material in the AL-STAR impact limiter, which was evaluated in a series of ¼-scale 9-m drop tests conducted at the Oak Ridge National Laboratories (ORNL) in the late 1990s to demonstrate regulatory compliance of the HI-STAR 100 package design. The test data was recently used to provide the data points for the LS-DYNA benchmarking analyses reported in this paper. The LS-DYNA model based on the actual configuration of the ¼-scale test model is used to simulate the one unsuccessful and four successful tests documented in the HI-STAR 100 ¼-scale test report. Results predicted by LS-DYNA show an excellent agreement with the scale model test data in respect to all key metrics, namely, maximum deceleration, extent of crush, duration of impact, and overall profile of the deceleration curve. The failure of the impact limiter attachment bolts, observed in the initial side drop test, is also correctly predicted by LS-DYNA. The LS-DYNA benchmarking analysis indicates that the structural response of an aluminum honeycomb impact limiter and preloaded bolt joints under the hypothetical drop condition can be accurately predicted through a finite element (FE) analysis.