The Incorporation of Experience-based Data into the Markov Maintenance Model and an Impact of Changed Maintenance Intervals on Plant Reliability

At present, preventive and scheduled maintenance activities are mainly performed at Japanese nuclear power plants. Overhauling and other maintenance activities on equipment are carried out at relatively short intervals mostly during outages. In the U.S., on the other hand, condition-based maintenance are carried out more often than preventive maintenance; however, in recent years, a proper combination of preventive maintenance and condition monitoring activities has been performed based on the information about risks. Moreover, NUREG outlines the Markov Maintenance Model that makes a macroscopic assessment of conditions of equipment. Under these circumstances, much scientific attention is being devoted to an effective mixture of preventive maintenance, condition-based maintenance and corrective maintenance as adopted in the U.S., and to research into reasonable intervals of inspections. This study looks into the rationalization of inspection intervals at Japanese power plants using the Markov Model.