A combined deterministic and probabilistic approach to estimate frequency of inadvertent criticality for a cask car lid drop event

This paper estimates the frequency of postulated accident scenarios in which combinations of equipment failures and/or human errors associated with the lifting and moving of the cask car lid during fuel bundle loading/unloading operations lead to conditions which produce a criticality. As noted in the paper, bounding values are used for values where uncertainty is large. However, in general best estimate values are used to determine the scenario frequencies. This is consistent with current methodology where best estimates are calculated for the frequency domain and conservative estimates are calculated for the consequence domain