Tornado missile risk analysis: probability modeling, simulation methodology, and case studies. Final report

Mathematical models of the contributing events to the tornado missile hazard at nuclear power plants have been developed in which the major sources of uncertainty have been considered in a probabilistic framework. These models have been structured into a sequential event formalism which permits the treatment of both single and multiple missile generation events. A simulation computer code utilizing these models has been developed to obtain estimates of tornado missile event likelihoods. Two case studies have been analyzed: a single unit plant using the current NRC set of missiles and a two unit arrangement using an expanded missile set. Preliminary results suggest that the likelihood of missile strike and that of subsequent plant damage may be acceptably small