TOKYO – Japan has restarted operations at the world’s largest nuclear power plant for the first time since the 2011 Fukushima disaster forced the country to shut all of its reactors.
The decision to restart reactor number 6 at Kashiwazaki-Kariwa north-west of Tokyo was taken despite local residents’ safety concerns.
It was delayed by a day because of an alarm malfunction and is due to begin operating commercially next month.
Japan, which had always heavily relied on energy imports, was an early adopter of nuclear power. But in 2011 all 54 of its reactors had to be shut after a massive earthquake and tsunami triggered a meltdown at Fukushima, causing one of the worst nuclear disasters in history.
This is the latest installment in Japan’s nuclear power reboot, which still has a long way to go.
The seventh reactor at Kashiwazaki-Kariwa is not expected to be brought back on until 2030, and the other five could be decommissioned. That leaves the plant with far less capacity than it once had when all seven reactors were operational: 8.2 gigawatts.
Triggered by the most powerful earthquake ever recorded in Japan, the meltdown in the reactors at Fukushima Daiichi, 220 km north-east of Tokyo on the coast, led to radioactive leakage. Local communities were evacuated, and many have not returned despite official assurances that it was safe to do so.
Critics say the plant’s owner Tokyo Electric Power Company, or Tepco, was not prepared, and the response from them and government was not well co-ordinated. An independent government report called it a “man-made disaster” and blamed Tepco, although a court later cleared three of their executives of negligence.
Still the fear and lack of trust fueled public opposition to nuclear power and Japan suspended all of its 54 reactors shortly after the Fukushima disaster.
It has now spent the past decade trying to wake up those power plants, as it seeks to reach net zero emissions by 2050.
Since 2015, Japan has restarted 15 out of its 33 operable reactors. The Kashiwazaki-Kariwa plant is the first of those owned by Tepco to be turned back on.
Before 2011, nuclear power accounted for nearly 30% of Japan’s electricity and the country planned to get that up to 50% by 2030. Its energy plan last year unveiled a tamer goal: it wants nuclear power to provide 20% of its electricity needs by 2040.
Even that may be tricky.
‘A drop on a hot stone’
Global momentum is building around nuclear energy, with the International Atomic Energy Agency estimating that the world’s nuclear power capacity could more than double by 2050. In Japan, as of 2023, nuclear power accounted for just 8.5% of electricity.
Prime Minister Sanae Takaichi, who took office in October 2025, has emphasized the importance of nuclear power for Japan’s energy self-sufficiency. Especially as it expects energy demand to surge because of data centers and semiconductor manufacturing.
Japan’s leaders and its energy companies have long pushed for nuclear power. They say it’s more reliable than renewable energy like solar and wind, and better suited for Japan’s mountainous terrain. But critics say the emphasis on nuclear energy has come at the cost of investing in renewables and cutting emissions.
Now, as Japan tries to revive its nuclear power ambitions, the costs of running the reactors have surged, partly because of new safety checks that require hefty investments from companies trying to restart plants.
“Nuclear power is getting much more expensive than they ever thought it would,” says Dr. Florentine Koppenborg, a senior researcher at the Technical University of Munich.
The government could subsidize the costs, or pass them on to consumers – both unpalatable options for Japan’s leaders, who have for decades been hailing the affordability of nuclear power. An expensive energy bill could also hurt the government at a time when households are protesting about rising costs.
The government’s “hands are tied when it comes to financially supporting nuclear power, unless it’s willing to go back on one of the main selling points,” Koppenborg says. “I think [Japan’s nuclear power revival] is a drop on a hot stone, because it does not change the larger picture of nuclear power decline in Japan.” (BBC)
