Abstract:
"Evaluation of Impact Tests of Solid Steel Billet onto Concrete Pads, and Application to Generic ISFSI Storage Cask for Tipover and Side Drop"
This paper details the evaluation of a series of impact tests on a solid steel billet and the application of the findings to a full-size "generic" spent fuel storage cask, with a focus on low-energy side drop and tipover events. To address a need for more realistic impact analyses, the Nuclear Regulatory Commission (NRC) funded a series of drop tests using a scaled billet and concrete pads to develop data for benchmarking analytical models. The authors developed a methodology that uses a finite element model of the billet, pad, and subgrade soil, created with the TrueGrid mesh generator, to simulate the physical tests. This modeling was performed using the nonlinear explicit finite element code DYNA3D, which is suitable for high-rate dynamic events like impacts. The model incorporated a simple elastic material model for the soil and a constitutive model for the concrete pad that was developed from previous research at Lawrence Livermore National Laboratory. The methodology involves filtering accelerometer data from both the physical tests and the simulations to isolate rigid body motion from vibratory components, allowing for a direct comparison. After validating the finite element model against the billet test data, the developed material properties for the concrete and soil were applied to a full-scale model of a generic cask to simulate tipover and side drop impacts. The study demonstrates that this benchmarked FEA approach can be reliably used to estimate deceleration loads on storage casks, providing a valuable tool for future quasi-static or dynamic analyses of internal components like the basket structure.
