Probabilistic Risk Assessment of Bolted Dry Spent Fuel Storage Cask

EPRI performed a Probabilistic Risk Assessment (PRA) of a dry spent fuel storage cask. The study was performed for a bolted cask at a “generic” pressurized water reactor site. A generic site was chosen so the widest variety of challenges could be considered. The study calculates the annual individual radiological risk and consequences associated with a single cask life cycle, where the life cycle is divided into three phases: loading, on-site transfer, and on-site storage. The project used standard methods of PRA with the following analysis tasks: initiating event (IE), data, human reliability, structural, thermal hydraulic, accident sequence, and consequence. The results shows that the risk is extremely low with no calculated early fatalities and a first year risk of latent cancer fatality of 3.5E−11 per year per cask. Subsequent year risk to the general public is even lower; with, again, no early fatalities and a cancer risk of 4.2E−12.