FAILURE OF EMERGENCY DIESEL GENERATORS - A POPULATION ANALYSIS USING EMPIRICAL BAYES METHODS

This paper presents analysis of failure data from a large population o f emergency diesel generators (EDGs) at nuclear power plants. Empirica l Bayes methods are used to estimate the population distribution and t he individual failure probabilities from EDG's failure to start and lo ad-run data over 4 years for 195 EDGs at 63 plant sites. Each diesel f ailure probability is treated as being a sample value from an underlyi ng population distribution. The statistical characteristics of the fai lure probability distributions (mean, variance, standard deflation and others) are estimated. The estimates of the failure probability distr ibutions are useful for evaluation of EDG reliability and can be used as prior distributions and in uncertainty propagations in probabilisti c risk assessments (PRAs).