Photo/Illutration The No. 3 reactor, left, and No. 4 reactor at the Takahama nuclear power plant in Takahama, Fukui Prefecture (Toshiyuki Hayashi)

The Nuclear Regulation Authority on May 29 approved extending the operating lives of two reactors in Fukui Prefecture to 60 years, the seventh and eighth such requests accepted by the nuclear industry watchdog.

The decisions concerning the No. 3 and 4 reactors at the Takahama nuclear power plant came despite a government policy of limiting reactor lifespans to 40 years in principle. That policy was adopted after the triple meltdown at the Fukushima No. 1 nuclear power plant in 2011.

The NRA has now approved all requests from plant operators to extend the lives of eight reactors across four plants to 60 years.

Kansai Electric Power Co., operator of the Takahama plant, applied in April last year for the lifespan extension for the two reactors, which went online in 1985.

With the reactors’ operating lives nearing the age limit, Kansai Electric used legal amendments approved in 2012 that allow a one-time 20-year extension to the 40-year operating limit for reactors, subject to NRA approval.

In its regular meeting on May 29, the NRA concluded that the extensions at the Takahama plant were appropriate. It said no issues with the reactor vessels and other critical facilities have been detected through ultrasonic and visual inspections.

It also confirmed Kansai Electric’s plans to replace damaged heat transfer tubes in steam generators used to drive turbines.

After the Fukushima nuclear disaster, the government, under the leadership of the Democratic Party of Japan, stated that operating-life extensions for reactors would be “limited to extremely exceptional cases.”

However, all applications submitted so far for 60-year operations have been approved.

They include the No. 1 and 2 reactors also at the Takahama plant, the No. 3 reactor at the Mihama nuclear power plant in Fukui Prefecture, the No. 1 reactor at the Tokai No. 2 nuclear power plant in Ibaraki Prefecture, and the No. 1 and 2 reactors at the Sendai nuclear power plant in Kagoshima Prefecture.

Fourteen other reactors around Japan are scheduled to exceed 40 years of operation within the next decade.

A new system to be fully introduced in June next year will allow for extending reactor operations beyond 60 years. This system allows operators to exclude from official lifespan calculations the periods when the reactors are idle due to NRA inspections.

A panel of experts at the industry ministry is currently discussing the calculation method for the exclusion periods.

According to a March 2023 report from the ministry, the periods that could be excluded are five years and nine months for the Takahama plant’s No. 3 reactor and six years and four months for the No. 4 reactor.

(This article was written by Shoko Tamaki and Fumi Yada.)

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