The empirical failure rate and repair rate of PWR primary coolant pumps

The wealth of operating experience concerning PWR nuclear reactors that has been regularly monitored and systematically processed since 1971, enabled an analysis of PWR primary coolant pump operation. Failure rate λ and repair rate μ of a pump during plant lifetime were calculated, as these values are necessary if we are to determine the reliability and availability of the pump as a basis for the analysis of its effect on the safety and efficiency of the nuclear power plant. The trend of failure rate λ is similar to the theoretically expected changes in λ over time, and this is around 1 × 10−5 in the majority of operation time. Repair rate μ indicates a slow rise during lifetime, i.e. a gradual shortening of pump repair time and thereby its faster return to operation.