PROBABILISTIC ANALYSIS OF A PREEMPTIVE REPLACEMENT OF AN NPP COMPONENT WITH A COMPONENT OF SUPERIOR MATERIAL

摘要

The Westinghouse proactive aging management tool, PAM, considers three major sets of variables when calculating the NPV or economic value of age replacement: (a) the projected time to failure, (b) the economic consequences of unplanned failure and (c) the cost of the replacement. All of these variables will typically be uncertain; particularly the time to part failure. A not uncommon complication in evaluating whether and when to replace a degrading component or part in a plant is that the replacement part is thought to have a longer expected life (be more resistant to degradation) but, to date, there is little field experience to substantiate that belief. This paper shows how two different approaches for statistical estimation of a Weibull failure distribution can be used in tandem to surmount this problem, and illustrates it within the context of the replacement of a nuclear power plant component tube bundle with a tube bundle expected to provide superior corrosion resistance.