FUKUI, Japan (Kyodo) -- An aging nuclear reactor in central Japan's Fukui Prefecture was restarted Wednesday, becoming the country's first nuclear unit to operate beyond the government-mandated 40-year service period introduced under new rules set after the 2011 Fukushima disaster.
Kansai Electric Power Co. said it began operating the No. 3 unit at the Mihama plant for the first time in about 10 years, after completing final inspections. The reactor had stopped operations after the crisis at the Fukushima Daiichi plant, triggered by a massive earthquake and tsunami.
However, the Mihama No. 3 unit, which began commercial operation in 1976, is expected to be halted in about four months, before the Oct. 25 deadline for the implementation of counterterrorism measures that Kansai Electric is unlikely to meet, according to the company.
The Nuclear Regulation Authority granted approval in 2016 for the reactor to operate beyond the 40-year limit for an additional period of up to 20 years, after screening the company's safety measures for the unit.
In February, Mihama Mayor Hideki Toshima also gave his consent for the resumption, followed by approval from Fukui. Gov. Tatsuji Sugimoto on April 28, despite increasing worries about aging nuclear reactors among local residents.
On Monday, a group of nine people in Fukui as well as neighboring Kyoto and Shiga prefectures filed a lawsuit with the Osaka District Court seeking suspension of the Mihama No. 3 reactor.
They argued that aging reactors are prone to accidents when a massive earthquake occurs and that the 40-year operation period should be strictly applied in the country, which could be hit by a natural disaster anytime.
The Nos. 1 and 2 units of the Mihama plant were terminated in April 2015 in line with the 40-year limit.
Two other Kansai Electric reactors in Fukui Prefecture have also secured nuclear watchdog approval and local consent to operate beyond the 40-year limit.
But the Nos. 1 and 2 reactors at the Takahama plant will not resume operation, as the utility failed to meet a June 9 deadline to complete the implementation of counterterrorism measures.