A PSA framework for an Interim Dry Storage Facility Subjected to an Aircraft Crash

Abstract

An overview of a risk evaluation framework for an aircraft crash into an interim spent fuel storage facility using a probabilistic safety assessment is presented. Damages evaluation of a detailed generic cask model in a simplified
building structure under aircraft impact is discussed through a numerical structural analysis and an analytical fragility assessment. Sequences of the impact scenario are shown in a developed event tree, with uncertainties considered in the impact analysis and failure probabilities calculated. Risks are estimated for three specification levels of cask and storage facility structures to evaluate the influence of parameters relevant to design safety. The proposed assessment procedure includes the determination of loading parameters and reference impact scenario, structural response analyses of facility walls, cask containment, and fuel assemblies, and a radiological consequence analysis with dose-risk estimation. The risk results for the proposed scenario in this study are expected to be small relative to design basis accidents for best-estimated, conservative values. The importance of this framework is seen in the flexibility to evaluate facility capability to withstand aircraft impact and the expectation of potential realistic risks; the framework also provides insight into epistemic uncertainty in the available data, and into the sensitivity of design parameters for structural health management of interim dry storage facility.