Package Impact Models as a Precursor to Cladding Analysis1

The evaluation of spent nuclear fuel storage casks and transportation packages under impact loading is an important part of cask and package certification by the United States Nuclear Regulatory Commission. Finite element models are increasingly used for evaluating cask and package structural integrity during hypothetical drop accidents. Full cask and package model results are also used as the loading basis for single fuel pin impact models, which evaluate the response of fuel cladding under drop conditions. In this paper, a simplified package system is evaluated to illustrate the difference between local and bulk impact responses, the effect of simplified basket and fuel assembly representations, and the effect of gaps between components. This paper focuses on the package impact analysis and how loading conditions for a subsequent fuel assembly or fuel cladding analysis can be extracted. The results of this study suggest that detailed package system models are needed to determine cladding deceleration load histories.