The governor of Japan's Fukui Prefecture on 28 April  approved the restart of three reactors owned by Kansai Electric Power Company - Takahama units 1 and 2, and Mihama unit 3. His consent was the final approval needed for the reactors - all aged over 40 years old - to resume operation.

Kansai's four-unit Takahama plant (Image: NRA)

At a press conference, Fukui Governor Tatsuji Sugimoto said he reached the decision after considering the matter based on the prefecture's three nuclear principles of securing safety, gaining residents' understanding and improving welfare, Jiji Press reported. "Taking all circumstances into account, I agreed to the restarts," he said.

In a statement today, Kansai said: "We would like to express our deep gratitude to the Governor for making his decision in consideration of this. In addition, the Governor of Fukui Prefecture and other Fukui citizens have been involved in the nuclear power business. Thank you for your understanding and support, and for your efforts in the stable supply of electric power."

Kansai is now discussing the exact schedule for bringing the reactors back online, the Japan Times said, but other media reports suggest it could be within two months.

Sugimoto's approval for the reactor restarts followed that of the Fukui prefectural assembly on 23 April.

Under revised regulations which came into force in July 2013, Japanese reactors have a nominal operating period of 40 years. Extensions may be granted once only and are limited to a maximum of 20 years, contingent on exacting safety requirements.

In June 2016, Takahama 1 and 2 - both 780 MWe (net) pressurised water reactors (PWRs) - became the first Japanese units to be granted a licence extension beyond 40 years under the revised regulations. The units began operating in 1974 and 1975, respectively. In November 2016, the Nuclear Regulation Authority approved an extension to the operating period for Mihama 3, also a 780 MWe PWR, which entered commercial operation in 1976.

Kansai recently completed upgrades aimed at preparing the three units for operation beyond 40 years. At Takahama 1 and 2, work has been carried out to reinforce their containment buildings. Kansai has reinforced the existing concrete wall surrounding the containment vessel of each unit, as well as installed secondary domes. Most of the work at Mihama 3 was related to improving the unit's seismic resistance.

Researched and written by World Nuclear News