Application of probability risk assessment in TRP and its capability to maintenance planning

Takase, Yuki; Miura, Yasushi ; Nakabayashi, Hiroki 

Tokai Reprocessing plant (TRP), which temporarily suspended the reprocessing of spent fuel in 2007, moved to decommissioning in 2018 without restarting operations. Under the decommissioning situation, the high-level radioactive liquid waste generated in the past reprocessing operation is the highest potential risk in TRP. These high-level radioactive liquid wastes are stored in High Active Liquid Waste Storage Facility (HAW) and sequentially Vitrified in Tokai Vitrification Facility (TVF). The serious accident risk about evaporation accident of high radioactive liquid waste has been remained in both facilities. In this study, a loss of heat sink (LOHS) frequency of high radioactive liquid waste in HAW and TVF was assessed by Probability Risk Assessment (PRA). The risk information was extracted for the equipment of important of safety related system from the view point of maintaining the facility safety. Its capability to maintenance planning was evaluated.