Experience of RCM analysis and evaluation method of establishing critical components in Korean NPPS

The analysis of Reliability Centered Maintenance (RCM) for three pilot system of Yonggwang nuclear power unit 1, 2 had been performed from 1997 to 1999. The objective of this analysis was to optimize the preventive maintenance program. For evaluation of critical component, FMEA (Failure Mode and Effect Analysis) and Instrument matrix method had been used in the analysis. As results of the analysis, about 25% of total component was identified as critical component, and the number of preventive maintenance (PM) tasks has been reduced by about 18% compared with current PM tasks. Also as for the types of PM tasks, time-directed tasks were reduced from 75% to 55%, while condition-directed tasks and failure finding tasks were increased from 2% and 23% to 9% and 36%, respectively. Based on this analysis of pilot system, the RCM analysis on extended 25 systems of the same unit has started from 2000 to 2002. In this study, the evaluation method for establishing critical component that can be used for selection of the SSC(system, structure, component) in maintenance rule has been developed. This method is simpler and cost-benefit than FMEA method. In this paper, the results of RCM analysis on pilot systems of Yonggwang nuclear power unit 1 and 2 and evaluation method for determining critical component used in our nuclear power plant are described. Also the future plan for maintenance strategies on the all NPPs in Korea are described. (author)