Japan restarts 1st reactor at world’s largest nuclear plant since Fukushima

TEPCO brought back online the No. 6 reactor at the seven-unit Kashiwazaki-Kariwa complex in Niigata Prefecture -- northwest of Tokyo and the world's largest nuclear power plant by output when fully operational -- after a last-minute control-rod alarm failure during a test forced it to delay the resumption initially set for Tuesday.

The operator reassessed whether the unit can be restarted after the control-rod alarm, designed to sound when two or more control rods are withdrawn from the reactor fuel core, failed to activate during a test Saturday at the complex.

TEPCO reported to the nuclear regulators that it completed its final inspection of the control rods early Wednesday.

The restart comes as safety concerns over the nuclear plant's operation have reignited after Chubu Electric Power Co. was found to have selected favorable seismic ground-motion data when establishing earthquake-resistant standards for the Hamaoka plant in Shizuoka Prefecture, bringing the safety screening process back to square one for further investigation.

Following a regular checkup of the No. 6 unit in March 2012, none of the reactors at the Kashiwazaki-Kariwa complex -- which has the same type of boiling water reactors as the crippled Fukushima Daiichi complex -- could be restarted due to public concerns about nuclear power safety following the Fukushima disaster, as well as doubts about TEPCO's ability to operate the complex.

In 2013, TEPCO applied to the Nuclear Regulation Authority for inspections of Nos. 6 and 7 reactors under the stricter government safety standards imposed following the multiple meltdowns at the Fukushima Daiichi nuclear power complex, triggered by a massive earthquake and tsunami in 2011.

The regulators said the reactors met the standards in December 2017. However, TEPCO was banned from restarting the plant for over two and a half years due to flaws in its anti-terrorism measures, including unauthorized access to the main control room.

The process of obtaining the necessary local consent also progressed slowly. It took the Niigata prefectural government around a decade to compile its own investigations into the Fukushima accident before deciding to approve the restart.

In November, despite a survey showing that residents were split over the reboot, Niigata Gov. Hideyo Hanazumi declared his support for restarting the Nos. 6 and 7 units. The central government asked him to greenlight the resumption to ensure a stable electricity supply and to revamp TEPCO's businesses.

The resumption of the No. 6 unit marks the 15th reboot since the Fukushima accident among the country's 33 operable nuclear reactors.

The Japanese government has shifted its energy policy to maximize the use of nuclear power, viewing it as a stable and carbon-free energy source.

TEPCO faces massive compensation costs and other expenses related to the 2011 nuclear accident. The company believes that restarting the reactors will increase revenues, which can be used to compensate those affected by the Fukushima nuclear accident, while lowering utility costs.

Nearly 15 years after the March 11, 2011, Fukushima accident, many residents still cannot return home due to high radiation levels. Although TEPCO has stuck to its road map to decommission the Fukushima Daiichi plant by 2051, it has repeatedly postponed the process due to various difficulties.

At the Kashiwazaki-Kariwa complex, TEPCO ultimately decided to prioritize restarting the No. 6 reactor, while it is considering scrapping the Nos. 1 and 2 units.

As previously reported, Japan may consider reviewing 3 non-nuclear principles.