Integrated Level III risk assessment for the LaSalle Unit 2 Nuclear Power Plant

In this paper we discuss the methodology and results of the integrated Level III Probabilistic Risk Assessment (PRA) of the LaSalle County Station Unit 2 Nuclear Power Plant. Methods were developed for integrating internal and external events into one analysis based on a common model of the plant and a common method for representing the output. Additional methods were developed for representing and propagating uncertainties in the basic inputs to the models to determine their effects on the final (or intermediate) results. The integrated core damage frequency for the LaSalle plant is 1.01E-4/R-yr., with a 5th percentile of 5.34E-6/R-yr., a median value of 2.92E-5/R-yr., and a 95th percentile of 2.93E-4/R-yr. The dominant sequence is short-term station blackout. The risk from the LaSalle plant is low, especially with respect to the NRC safety goals. The mean individual early fatality risk within one mile and the mean individual latent cancer risk are 1.1E-10/R-yr. and 8.5E-9/R-yr., respectively; both of which are several orders of magnitude less than the safety goals. 10 refs., 11 figs., 7 tabs.