Risk management in Taiwan's nuclear power plants by adopting TIRM-2

The TIRM-2 is the second generation risk monitor developed by INER and TPC. By providing risk indexes such as CDF, LERF, ΔCDF, ΔLERF, importance measurements and availability of safety systems, the TIRM-2 can precisely capture the plant risks and can serve as a better management resource. Examples about how to use TIRM-2 for the risk management are discussed in this paper. For plant at power operation, the TIRM-2 allows the plant staff to change plant configuration directly from the P and I Diagram. For a new plant configuration, only a few minutes will be spent for TIRM-2 to recalculate all the risk indexes. TIRM-2 can also provide risk profile and the associated risk indexes based on a given online maintenance schedule. The risk profile of CDF and LERF with ΔCDF and ΔLERF will help the plant staff with preparing associated information for the applications of risk-informed, performance-based regulation. With the proposed refueling outage schedule, the TIRM-2 can predict status of safety system and risk profile of CDF hourly. All calculations can be done within 40 minutes for a typical 50-days outage schedule. The plant staff and managers can rearrange the maintenance schedule referring to TIRM-2' predicted results and avoiding the plant entering into a potential high-risk situation. With the capability of performing both CDF and LERF calculations, the TIRM-2's will become a very helpful tool in monitoring the risk of different plant status and will provide further information directly for risk-informed applications. (author)