External events analysis for the Savannah River Site K reactor

The probabilistic external events analysis performed for the Savannah River Site K-reactor PRA considered many different events which are generally perceived to be ''external'' to the reactor and its systems, such as fires, floods, seismic events, and transportation accidents (as well as many others). Events which have been shown to be significant contributors to risk include seismic events, tornados, a crane failure scenario, fires and dam failures. The total contribution to the core melt frequency from external initiators has been found to be 2.2 x 10-4 per year, from which seismic events are the major contributor (1.2 x 10-4 per year). Fire initiated events contribute 1.4 x 10-7 per year, tornados 5.8 x 10-7 per year, dam failures 1.5 x 10-6 per year and the crane failure scenario less than 10-4 per year to the core melt frequency. 8 refs., 3 figs., 5 tabs