The NUREG-1150 probabilistic risk assessment for the Surry nuclear power station

This paper summarizes the findings of the probabilistic risk assessment for Unit 1 of the Surry Power Station performed in support of NUREG-1150. The emphasis is on the 'back-end' analyses, that is, the accident progression, source term, and consequence analyses, and the risk results obtained when the results of these analyses are combined with the accident frequency analysis. The results show that the risk from internal initiators is well below the safety goals and is somewhat lower than estimated by Reactor Safety Study (RSS) over a decade ago. The risk from internal initiators is dominated by bypass accidents in the current analysis. The risk from seismic initiators is comparable to or greater than the risk from internal initiators, but still less than that estimated for internal initiators in the RSS. The uncertainty band for both types of initiators is considerably greater than that estimated in RSS. (orig.)