Structural integrity assessments of SNF transport cask and fuel cladding under hypothetical explosion scenario

Abstract

Ensuring the integrity of spent nuclear fuel (SNF) transport cask during extreme accident as well as normal conditions is essential for public and environmental safety. In this study, a series of explosion analyses were conducted for an SNF transport cask and fuel cladding based on a representative hypothetical explosion scenario. First, three numerical methods, namely the conventional weapons effects program, smoothed particle hydrodynamics and coupled Eulerian-Lagrangian, were benchmarked against experimental data from a steel pipe explosion to identify the most reliable one. Finite element (FE) analyses of the transport cask were then primarily performed by considering different detonation angles and configurations with and without the impact limiters. The influence of explosive shapes including cube, cylinder, and sphere was also examined by comparing the resulting shock wave propagation in each cask component. The structural integrity assessment revealed that the factor of safety for all cask components exceeded 1.5 except in the case of a 0° detonation angle. Accordingly, the detailed FE model of an SNF assembly was developed and its integrity was assessed. The subsequent FE analyses showed that the resulting strains remained well below the strain-based failure criterion for all detonation angles in both configurations, suggesting that the limited damage to the cask would not compromise the integrity of the SNF fuel cladding.