Kansai Electric has submitted an application to Japan’s Nuclear Regulation Authority (NRA) for a 20-year operating extension for the units 3&4 of the Takahama NPP in Fukui Prefecture.

The two reactors will reach the end of their 40-year operating lives in 2025. Kamsai completed the special inspection required for an operating extension between September and November 2022 and no problems were found.

However, damage to heat-transfer pipes of the steam generator was discovered in both reactors. The Fukui prefectural and Takahama municipal governments have both consented to the replacement of the generators and replacement work will take place between June 2026 and February 2027.

The two reactors have also faced other problems. In January, unit 4 automatically stopped after a sensor detected a problem. Utility officials believe a loose connection in an electrical cable led to the control rods being inserted into the reactor core. Company officials attributed the incident to bad workmanship rather than degradation of the equipment due to ageing. The unit resumed operations in late March.

After the 2011 Fukushima Daiichi accident, regulations were tightened and the operating life of reactors was restricted to 40 years, with a single 20-year extension allowable with NRA approval. So far, four reactors have been approved for such extensions, including the Takahama 1&2, Kansai’s Mihama NPP unit 3 and unit 2 at JAPC’s Tokai NPP. The application Takahama 1&2 was submitted in April 2015 and approved by the NRA in June 2016.

Japan's Diet (parliament) is considering legislation that would allow NPPs to operate beyond their 60-year limit after the new policy was approved by both NRA and the government. However, Kansai Electric plans to proceed with the extension application under the current system.

Image: Takahama nuclear power plant (courtesy of Kansai Electric)