Japan's Mihama Nuclear Power Plant Unit 3 Receives Preliminary Approval for Operation Plan Beyond 50 Years

On August 25, Japan's Nuclear Regulation Authority (NRA) gave preliminary approval to Kansai Electric Power Co. (KEPCO) for the long-term facility management plan for Unit 3 of the Mihama Nuclear Power Plant. Located in Mihama Town, Fukui Prefecture, the unit will mark its 50th anniversary of commercial operation on December 1.

In May of this year, the metal top cover of the high-pressure turbine at Mihama Unit 3 suffered damage, resulting in steam leakage. At the NRA meeting held that day, KEPCO explained that the cause of the incident was believed to be thinning of the inner wall of the top cover due to steam flow. The company stated that this phenomenon falls under previously anticipated aging and degradation management for turbine equipment, and that the existing plan already includes corresponding management measures. Visual inspection and other examination methods were also deemed applicable, thus no revision to the long-term facility management plan was required.

The Nuclear Regulation Authority has required KEPCO to prevent similar incidents from recurring through periodic inspections. Under the current procedure, the plan is expected to receive formal approval in the near future.

If approved for operation beyond 50 years, Mihama Unit 3 will become Japan's third nuclear unit to operate for more than 50 years, following KEPCO's Takahama Nuclear Power Plant Units 1 and 2.