DEVELOPMENT OF THE RISK MONITORING SYSTEM 'COSMOS' AND APPLICATION FOR THE RISK EVALUATION DURING ONLINE MAINTENANCE

摘要

The Japanese utilities have been applying risk monitoring system. It was first intended to introduce risk monitoring system for outage work planning. In addition, the utilities are considering the possibility of applying risk monitoring system to on-line maintenance (0LM) in the near future, and making necessary preparations in a steady manner. The Kansai Electric Power Company (KANSAI) and Nuclear Engineering Ltd. (NEL) are jointly working to develop the risk monitoring system "COSMOS" aiming at the utilization of the system to optimize nuclear power plant (NPP) operation and maintenance activities. COSMOS, which is intended for level 1 PSA at power and during shutdown, has the complete linkage with the comprehensive PSA tool, RISKMAN, which is widely adopted by NPPs at home and abroad. This paper explains how KANSAI and NEL are working on the application of risk monitoring system in planning the outage work and on-line maintenance activities. Regarding the outage work planning, KANSAI' s plants are conducting Level 1 shutdown PSA by using a simplified risk monitoring system now, and planning to introduce COSMOS for the future outage work planning. In planning OLM activities, it is necessary to evaluate the risk levels of individual configurations in advance in which specific systems and components are placed out-of-service according to the predetermined scope of isolation. It is planned to apply COSMOS to the evaluation of risk levels. We will make a continuous effort to extend COSMOS functions considering experience with the actual application of risk monitoring system in OLM and outage work planning.