Japan's Mihama Nuclear Power Station Unit 3 Plans Grid Connection on September 15

Kansai Electric Power announced on September 1, 2026, that work related to the periodic inspection of Unit 3 at Japan's Mihama Nuclear Power Station is progressing as planned. Based on the progress of the inspection and the status of corrective measures for the steam leakage issue in the high-pressure turbine, the unit is scheduled to be connected to the grid on September 15.

Unit 3 of Mihama Nuclear Power Station is a pressurized water reactor unit with a rated electrical output of 826 MW and a rated thermal output of 2,440 MW. On May 8 this year, the unit underwent a manual reactor shutdown after steam leakage was confirmed in the high-pressure turbine. From June 16, the unit entered its 29th periodic inspection.

Kansai Electric Power stated that, in response to the steam leakage in the high-pressure turbine, the upper cylinder sealing cover has been replaced based on the results of the cause investigation, and multiple measures such as the development of relevant guidelines are being advanced. Additionally, the company has re-verified all equipment through which high-temperature, high-pressure steam or water flows to confirm that appropriate maintenance has been implemented.

Based on the current situation, Kansai Electric Power will continue to advance reactor startup preparations and plans to achieve grid connection on September 15. The company stated that it will steadily proceed with the remaining work of the periodic inspection while ensuring safety remains the top priority.