A reactor returns after 15 years: what Japan’s restart really means

Japan’s energy landscape flickered back to life this week when Tokyo Electric Power Company (TEPCO) restarted Reactor No. 6 at the Kashiwazaki-Kariwa nuclear power plant — the first time a TEPCO-run reactor has been brought back into operation since the 2011 Fukushima disaster. The move is heavy with symbolism: nearly 15 years after one of the worst nuclear accidents in modern history, Japan is again turning toward large-scale nuclear generation to meet climate and energy-security goals. (ans.org)

Quick takeaways

• The No. 6 reactor at Kashiwazaki-Kariwa was restarted on 21 January 2026; the operator later suspended operations briefly after a control-rod-related glitch, saying there was no immediate safety impact. (ans.org)
• Kashiwazaki-Kariwa is the world’s largest nuclear generating complex by capacity; restarting even one unit adds substantial output to Japan’s grid. (ans.org)
• Restarts reflect a national policy pivot: Japan is re-embracing nuclear power to cut emissions and reduce reliance on imported fossil fuels, even as local opposition and seismic safety concerns persist. (theguardian.com)

The moment and the backdrop

On 21 January 2026 TEPCO withdrew control rods from Unit 6, bringing the reactor to criticality and initiating the carefully staged process of producing steam and testing systems before commercial operation. The plant — located in Niigata prefecture on the Sea of Japan coast — has seven reactors and a combined potential capacity that makes it the largest single nuclear site in the world. (ans.org)

That scale matters politically and practically. Japan’s energy mix has been reshaped by the 2011 earthquake, tsunami and ensuing meltdown at Fukushima Daiichi; nearly all reactors were shut down for safety overhauls, public trust eroded, and the country leaned on imported gas and coal. In recent years, under pressure from high fossil-fuel costs and climate targets, Tokyo has shifted back toward reactivating reactors that meet updated safety rules. (theguardian.com)

Why this restart matters

• Energy and emissions: Restarting Unit 6 can add gigawatts of low-carbon baseload power to the grid, helping the government pursue carbon neutrality goals while reducing costly fuel imports. That’s a major driver of the policy reversal toward “maximizing” nuclear capacity through 2040. (theguardian.com)
• TEPCO’s reputation and finances: TEPCO still manages the long, expensive Fukushima decommissioning. Bringing a flagship plant back online helps its bottom line — but also reopens questions about the company’s stewardship and transparency. (apnews.com)
• Local trust and seismic risk: Many residents near Kashiwazaki-Kariwa oppose the restart; surveys and protests reflect anxieties about earthquakes, evacuation readiness and whether local communities truly consented. Seismic safety remains a top concern in any Japanese nuclear debate. (aljazeera.com)

The hiccup: why the suspension matters

Hours after the restart began, TEPCO suspended operations to investigate an electrical malfunction related to control-rod equipment. The company emphasized the reactor remained stable and there was no release or visible safety threat — but the interruption underlines two realities: nuclear systems require near-perfect coordination of complex controls, and public confidence is fragile; even small technical issues are newsworthy and politically charged. (aljazeera.com)

That suspension won’t be judged solely on engineering grounds. In the court of public opinion, it feeds narratives on whether nuclear restarts truly resolved the problems that followed Fukushima: maintenance rigor, independent oversight, and evacuation planning.

Broader implications

• Energy security vs. social license: Japan faces a classic policy trade-off: nuclear offers reliable, low-carbon power but requires broad local trust and robust safety culture. The national goal of increasing nuclear’s share by 2040 makes restarts politically attractive — but local opposition and history complicate implementation. (theguardian.com)
• Global ripple effects: Japan is the world’s third-largest economy. Its nuclear policy choices influence global markets for LNG and coal, and signal how advanced economies balance decarbonization with energy resilience. (theguardian.com)
• Technical and regulatory watch: The Nuclear Regulation Authority and TEPCO will be scrutinized at every step — from post-restart inspections to the ramp-up to commercial operation — and any further malfunctions could stall public and political support. (ans.org)

My take

Restarting Unit 6 at Kashiwazaki-Kariwa is not just a technical milestone; it’s a test of whether Japan can reconcile climate goals, energy security and community consent after a traumatic chapter in its modern history. The engineering checks and regulatory approvals matter — but so do transparent communication, honest acknowledgement of past failures, and demonstrable local protections. If Japan’s next steps prioritize both rigorous safety and genuine engagement with affected communities, this restart could be part of a pragmatic, low-carbon pathway. If not, it risks reopening the social wounds left by Fukushima while adding political volatility to the energy transition.

What to watch next

• TEPCO’s investigation results and whether the reactor resumes stable operation and moves to commercial generation (TEPCO had signalled a target for commercial operation after additional checks). (ans.org)
• Niigata local politics and any legal or regulatory challenges from citizen groups and prefectural bodies. (theguardian.com)
• Japan’s national energy roadmap and whether the government adjusts timelines or safety conditions in response to operational lessons and public feedback. (theguardian.com)

Sources

• Japan edges closer to restarting world's biggest nuclear power plant. BBC News. https://feeds.bbci.co.uk/news/articles/cev8j9ylr14o. (feeds.bbci.co.uk)
• TEPCO restarts Kashiwazaki-Kariwa Unit 6. American Nuclear Society / ANS. https://www.ans.org/news/2026-01-21/article-7689/. (ans.org)
• Japan shuts reactor at world’s biggest nuclear plant a day after restart. Al Jazeera. https://www.aljazeera.com/news/2026/1/22/japan-shuts-reactor-at-worlds-biggest-nuclear-plant. (aljazeera.com)
• Nuclear reactor owned by Fukushima plant operator TEPCO suspends hours-old restart. Associated Press via ABC News. https://abcnews.go.com/Technology/wireStory/nuclear-reactor-owned-fukushima-plant-operator-tepco-suspends-129445073. (abcnews.go.com)
• 'An act of betrayal': Japan to maximise nuclear power 14 years after Fukushima disaster. The Guardian. https://www.theguardian.com/world/2025/feb/12/japan-nuclear-power-plan-emissions-targets-fukushima. (theguardian.com)