Takahama units cleared for extended operation

29 May 2024

Japan's Nuclear Regulation Authority (NRA) has approved the operation of units 3 and 4 at Kansai Electric Power Company's Takahama nuclear power plant in Fukui prefecture for a further 20 years. Both reactors are currently in operation and will reach their 40th anniversaries in January and June of 2025, respectively.

Takahama units 3 and 4 (Image: Kansai)

Under regulations which came into force in July 2013, Japanese reactors have a nominal operating period of 40 years. One extension to this - limited to a maximum of 20 years - may be granted, requiring amongst other things, a special inspection to verify the integrity of reactor pressure vessels and containment vessels after 35 years of operation.

The Takahama plant is home to four reactors. Takahama 1 and 2 - both 780 MWe (net) pressurised water reactors (PWRs) - entered commercial operation in 1974 and 1975 respectively, while units 3 and 4 - 830 MWe PWRs - both began commercial operation in 1985. Takahama 1 and 2 became the first Japanese units to be granted a licence extension beyond 40 years under the revised regulations.

In November 2022, Kansai announced it planned to apply for regulatory approval to extend the operating life of Takahama units 3 and 4 by a further 20 years. The company said it had carried out special inspections and evaluations of the two units, and had not found any issues likely to cause problems if the operating period were to be extended to 60 years. It also announced plans to replace the steam generators at the two units during scheduled outages, from June to October 2026 for unit 3 and October 2026 to February 2027 for unit 4.

Kansai applied to the NRA for the operating extension in April 2023.

The NRA has now approved the extension, making Takahama 3 and 4 the seventh and eighth Japanese reactors to be permitted to operate beyond 40 years.

"We will continue to strive to improve the safety and reliability of our nuclear power plants and utilise nuclear power generation as an important source of energy, with the understanding of local residents and others," Kansai said.

In December 2022, the NRA approved a draft of a new rule that would allow reactors to be operated for more than the current limit of 60 years. Under the amendment, the operators of reactors in use for 30 years or longer must formulate a long-term reactor management plan and gain approval from the regulator at least once every 10 years if they are to continue to operate. The new policy will effectively extend the period reactors can remain in operation beyond 60 years by excluding the time they spent offline for inspections from the total service life.

The legislation was approved by Japan's Cabinet in February and enacted in May 2023. It comes into effect in June 2025. Under the new policy - which describes nuclear power as "a power source that contributes to energy security and has a high decarbonisation effect" - Japan will maximise the use of existing reactors by restarting as many of them as possible and prolonging the operating life of aging ones beyond the current 60-year limit. The government also said the country will develop advanced reactors to replace those that are decommissioned.

Researched and written by World Nuclear News