World’s Biggest Nuclear Plant: Here’s all you need to know as Japan plans restart 15 years after Fukushima
The development marks a significant step in Japan’s long-running reassessment of nuclear energy following the earthquake and tsunami that triggered reactor meltdowns and widespread evacuations.
What is the Kashiwazaki-Kariwa plant and why is it important?
The Kashiwazaki-Kariwa plant, located in Niigata Prefecture, approximately 220 km northwest of Tokyo, consists of seven reactors and is operated by Tokyo Electric Power Company (TEPCO). It is the largest nuclear power plant in the world, with a total capacity exceeding 8,000 megawatts.
The plant has been offline since March 2011, when Japan shut down all nuclear reactors following the Fukushima Daiichi accident.
Since then, nuclear facilities across the country have been subject to new regulatory standards implemented by the Nuclear Regulatory Authority, including stricter requirements for tsunami protection, emergency power supplies and evacuation planning.
Its size and its operator’s association with the Fukushima disaster have made Kashiwazaki-Kariwa one of the most closely scrutinized and politically sensitive facilities in Japan’s nuclear fleet.
Why is Japan considering restarting now?
Japan’s move comes at a time when there has been a gradual return to nuclear energy production over the past decade. Fourteen of the country’s reactors, deemed compliant under revised safety rules, have restarted after going through regulatory reviews and local approval processes. Government energy policy documents say nuclear power is expected to play a role in stabilizing electricity supply and reducing dependence on imported fossil fuels. Japan imports the vast majority of its energy needs, making electricity prices vulnerable to fluctuations in the global fuel market.
Electricity demand has also increased in recent years, driven by industrial activity, digital infrastructure and the broader economic recovery.
According to Japan’s current energy strategy, nuclear energy is projected to account for approximately 20-22% of electricity production by 2030, alongside renewable energy sources and thermal energy.
The restart of Kashiwazaki-Kariwa would represent one of the largest additions to nuclear capacity since 2011.
How close is the restart?
Technical safety inspections by regulators at the Kashiwazaki-Kariwa facility have been completed and necessary improvements have been made.
In recent months, political processes at the local level have made progress, including decisions by the Niigata prefectural legislature advancing the ratification process.
At least one of the plant’s reactors could be restarted in early 2026, depending on final operational preparations and procedural steps, officials said.
TEPCO said it plans to invest significantly in safety measures, infrastructure and regional initiatives related to the plant’s operations in the coming years.
The restart schedule remains conditional and final decisions depend on coordination between the operator, regulators and local authorities.
What security reviews and public consultations have been carried out?
Government energy policy documents state that nuclear energy is intended to work alongside renewable energy sources in Japan’s electricity mix.
Restarting requires clearance from the nuclear regulator and completion of safety checks. Local authorities are also involved through approval procedures and coordination of preparatory measures.
With input from Reuters
