Photo/Illutration Shinsuke Yamanaka, chairman of the Nuclear Regulation Authority, on Nov. 2 (Ryo Sasaki)

The Secretariat of the Nuclear Regulation Authority on Nov. 2 proposed extending the maximum operating life of nuclear reactors beyond the current 60 years through additional safety inspections.

The NRA, the government’s nuclear power industry watchdog, is expected to reflect the change in a draft revision of the Nuclear Reactor Regulation Law by the end of the year.

Although allowing aging reactors to continue running has already drawn public criticism, NRA Chairman Shinsuke Yamanaka said at a Nov. 2 news conference that the new proposal “is a regulation much stricter than the current one.”

He noted that the reactors will have to undergo more safety checks to continue operating.

Under current rules introduced after the 2011 Fukushima nuclear disaster, the operating life of a nuclear reactor is 40 years, in principle.

But reactors and their vessels that pass the NRA’s degradation inspections before reaching the 40-year mark can operate for an additional 20 years.

The extension is allowed only once, so reactors at 60 years old must be decommissioned.

Under the new proposal, reactors in operation for 30 years must undergo inspections for signs of degradation. If they pass the tests, they can run for 10 more years.

Every decade, these reactors will have to undergo the degradation safety tests to continue operating. They could stay in operation beyond the current 60-year limit under this arrangement.

During the Nov. 2 meeting, an official of the NRA Secretariat said, “The safety risk due to ‘aging degradation’ increases as time passes.”

NRA members did not object to the proposal, but some said the safety inspections will require more attention.

The NRA has said examples of aging degradation include the reactor pressure vessel becoming brittle through neutron exposure, corrosion of the outer containment vessel, and deterioration of concrete’s strength.

At a green-transformation council meeting in August, Prime Minister Fumio Kishida instructed the economy ministry to discuss extending the operating life of nuclear reactors.

In October, the ministry explained to the NRA the government’s policy of reviewing the law to change the operation period of nuclear reactors.

Chairman Yamanaka said nuclear power plant operators decide on the period of operation of their reactors, but he instructed the NRA Secretariat to review the current system.

The Nuclear Reactor Regulation Law was revised to include the current 60-year limit in 2012, when the NRA was established.

The goal of Kishida’s policy change is to ensure a stable supply of energy while reducing greenhouse gas emissions.

The central government is also considering building more new reactors and rebuilding old ones.

Four reactors in Japan have been in operation for more than 40 years.

All of them have received approval for the extensions, but only one of them, the No. 3 reactor at Kansai Electric Power Co.’s Mihama plant in Fukui Prefecture, has resumed operations.

(This article was written by senior staff writer Eisuke Sasaki, Takuro Yamano and Ryo Sasaki.)

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