Japan restarts largest nuclear power plant post Fukushima disaster

Japan has restarted a nuclear reactor at the world’s largest atomic power plant for the first time since the 2011 Fukushima disaster, marking a significant milestone in the country’s long and cautious return to nuclear energy.

Tokyo Electric Power Co. (Tepco) began restarting Unit No. 6 at the Kashiwazaki-Kariwa nuclear power plant in Niigata prefecture on Wednesday, according to a company spokesperson.

The move had been scheduled for the previous day but was delayed after an alarm failed to activate during testing.

TEPCO said subsequent checks found no issues with the control rods.

The restart is the first for a Tepco-owned reactor since Fukushima and comes nearly 15 years after the disaster that reshaped Japan’s energy policy and public attitudes toward nuclear power.

A turning point for Japan’s energy policy

Kashiwazaki-Kariwa is the world’s biggest nuclear power plant, with seven reactors and a total capacity of 8.2 gigawatts when fully operational.

Unit No. 6 is the first to be restarted, while Unit No. 7 has also received regulatory approval but is not expected to come online until later.

The remaining five reactors may ultimately be decommissioned.

Before Fukushima, nuclear power accounted for nearly 30% of Japan’s electricity generation, and the government aimed to raise that share to 50% by 2030.

After the meltdown, Japan shut down its entire fleet of 54 reactors and became more reliant on imported fossil fuels.

Since 2015, the country has restarted 15 of its 33 operable reactors. Nuclear power currently supplies about 8.5% of electricity, and Japan’s latest energy plan targets a 20% share by 2040.

Japan’s renewed interest in nuclear energy aligns with a broader global trend.

Governments are seeking low-carbon power sources to decarbonize electricity grids, while companies face surging demand from data centers and artificial intelligence.

The International Atomic Energy Agency estimates global nuclear capacity could more than double by 2050.

Safety reforms and regulatory scrutiny

Following Fukushima, Japan established an independent Nuclear Regulation Authority (NRA) in 2012.

Restart approvals have taken years, reflecting stricter safety standards and local opposition.

Unit No. 6 at Kashiwazaki-Kariwa is the 15th reactor restarted under post-Fukushima rules.

Tepco said the restart process will involve further inspections of pumps, turbines and other equipment, with final regulatory clearance required before commercial operations can begin at the end of February.

“Based on the new safety standards, [Japan's nuclear plants] could survive even a similar earthquake and tsunami like the one we had in 2011,” said Hisanori Nei, a former senior nuclear safety official.

The plant has added 15-metre-high seawalls, watertight doors, and other protections.

Still, confidence remains fragile. In recent years, the facility has faced security lapses, including lost and mishandled confidential documents, which Tepco reported to regulators.

Economic realities and public opposition

Despite the restart, Japan’s nuclear revival faces financial and political hurdles.

New safety requirements have significantly raised operating costs. “Nuclear power is getting much more expensive than they ever thought it would,” said Florentine Koppenborg of the Technical University of Munich.

Public opposition also persists. Surveys after Fukushima showed support for reducing nuclear power rose sharply, and protests have continued near Kashiwazaki-Kariwa.

“If something was to happen at the plant, we would be the ones to suffer the consequences,” one protester said.

As Japan balances energy security, decarbonization goals, and public trust, the restart of Kashiwazaki-Kariwa signals progress — but also underscores how complex and constrained the path forward remains.