Nuclear Restarts After Fukushima: The Global Timeline
Nuclear restarts after Fukushima: Japan brought back 15 reactors, Belgium and South Korea reversed phase-outs, and 2025 set a record for nuclear power.
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Fifteen years after the Fukushima Daiichi accident forced Japan’s entire nuclear fleet offline and pushed Germany to accelerate its exit, the story has turned. Nuclear restarts after Fukushima are now a measurable global trend: Japan has brought 15 reactors back online, Belgium and South Korea have reversed phase-out policies, and global nuclear electricity generation hit a record high in 2025 for the second year running. But the picture is not one-directional — Germany completed its own nuclear exit in April 2023, and Taiwan went nuclear-free in May 2025. This timeline separates reactor restarts, lifetime extensions and new construction, and tracks exactly which countries reversed course, which didn’t, and why.
☢️ What’s Happening With Nuclear Restarts Right Now?
The March 2011 Fukushima Daiichi accident pushed Japan’s nuclear fleet to zero operating reactors by May 2012 and led Germany to accelerate a full phase-out, completed on 15 April 2023. Fourteen years later, the picture has shifted. Japan has restarted 15 reactors since Fukushima, with the 15th — Kashiwazaki-Kariwa Unit 6, the world’s largest nuclear plant by installed capacity — reaching commercial operation on 16 April 2026, the first TEPCO reactor to do so since the accident. Belgium agreed in 2022 to extend two reactors by 10 years, South Korea reversed a nuclear phase-down policy the same year, and more than 20 countries pledged at COP28 in December 2023 to triple global nuclear capacity by 2050. Global nuclear electricity generation reached a record high in 2025, the second consecutive record year, according to the IEA. But the trend is not universal: Germany’s exit stands, and Taiwan shut its last reactor in May 2025.
Fast Answers to the Questions Everyone Asks
What Actually Matters Here
- A “nuclear comeback” is really three different things. Restarting a suspended reactor (Japan), extending an operating reactor’s life (Belgium, the U.S.), and building an entirely new reactor (China, India) are distinct processes with different costs, timelines and risks.
- Japan’s restart took 15 years to reach 15 reactors. From zero operating reactors in September 2013 to Kashiwazaki-Kariwa 6’s commercial restart in April 2026, each return required new safety reviews, seismic and flood upgrades, and often court challenges.
- The direction is not universal. Germany completed its phase-out in April 2023 and has not reversed it; Taiwan shut its last reactor in May 2025. The “world is returning to nuclear” framing glosses over real exits.
- 2022 was the pivot year for policy reversal, not restarts. Russia’s invasion of Ukraine drove Belgium to extend Doel 4 and Tihange 3 by 10 years and South Korea’s new government to reverse a nuclear phase-down policy — both energy-security decisions, not safety reassessments.
- Kashiwazaki-Kariwa is symbolically loaded. It is operated by TEPCO, the utility behind Fukushima Daiichi, and is historically described as the world’s largest nuclear power station by installed capacity. Its Unit 6 reaching commercial operation on 16 April 2026 was TEPCO’s first commercial restart since the accident.
- COP28’s nuclear declaration keeps growing. More than 20 countries signed the pledge to triple global nuclear capacity by 2050 on 2 December 2023; the IEA reports over 40 countries now have policies supporting an expanded nuclear role.
- 2025 was nuclear’s second consecutive record year for generation. Global nuclear electricity output reached an all-time high, driven by Japanese restarts, stronger French output and new reactors coming online elsewhere.
- New construction has shifted east. Of the reactors that started construction worldwide since 2017, the IEA says 94% are of Chinese or Russian design — a geopolitical shift, not just a numbers one.
- AI and data-centre electricity demand is a new driver, not the original one. Rising demand from AI infrastructure has added momentum to U.S. efforts to revive closed reactors, on top of the older energy-security and climate arguments.
- Fukushima’s regulatory legacy is why restarts take years. Every returning reactor now requires enhanced flood barriers, backup power and severe-accident equipment under rules written in direct response to the accident.
The 3 Defining Moments Since Fukushima
One collapse, one policy reversal, one restart — each reshaped what came next.
The Full Timeline: Fukushima to the 2026 Restart Milestone
Newest first. Covers the decisions that actually shut down, restarted, extended or built nuclear capacity — not every policy statement.
Kashiwazaki-Kariwa 6 Reaches Commercial Operation Milestone
What happened: TEPCO’s Kashiwazaki-Kariwa Unit 6 officially resumed commercial operation at 16:00 local time, after commissioning tests confirmed no abnormalities in the reactor, generator or turbine. The reactor had been offline since March 2012.
Why it matters: TEPCO operates Fukushima Daiichi. This is the first time any TEPCO reactor has returned to commercial operation since the 2011 accident, and Kashiwazaki-Kariwa is historically described as the world’s largest nuclear power station by installed capacity.
Japan’s 15th Reactor Restarts Restart
What happened: Kashiwazaki-Kariwa Unit 6 was restarted at 14:00 local time after nearly 14 years offline, becoming the 15th Japanese reactor to resume operation since Fukushima forced the entire fleet to a halt.
Why it matters: With 15 reactors back online, Japan’s operating nuclear fleet reaches roughly 33 gigawatts of combined capacity — still well below the pre-Fukushima fleet, but enough to materially displace imported LNG.
Taiwan Shuts Its Last Reactor, Goes Nuclear-Free Exit
What happened: Taiwan Power Co. shut down Maanshan Unit 2, its last operating commercial reactor, completing a “nuclear-free homeland” policy the Democratic Progressive Party had pursued since taking office in 2016.
Why it matters: Taiwan is proof the global trend isn’t one-directional. Days after the shutdown, Taiwan’s legislature passed a proposal for a referendum on restarting the plant — and by March 2026 the government had opened a process that could lead to restarting Maanshan and another closed plant.
Global Nuclear Generation Hits a Record High — Second Year Running Record
What happened: Global nuclear electricity generation reached an all-time high in 2025, breaking the record set the previous year, according to the IEA and the World Nuclear Association.
Why it matters: The growth came from a combination of factors — Japanese restarts, stronger French reactor output, and new reactors entering operation in China, India, the UAE and elsewhere — not from any single country’s turnaround.
Shimane 2 Restarts Restart
What happened: Chugoku Electric Power restarted Shimane Unit 2, the second boiling-water reactor (the Fukushima design type) to return to service after Fukushima.
Why it matters: Boiling-water reactors were viewed as harder to restart politically because Fukushima Daiichi itself used that design. Shimane 2’s restart, five weeks after Onagawa 2, showed the BWR restart pathway was becoming routine.
Onagawa 2 Restarts — First BWR Back Online Restart
What happened: Onagawa Unit 2 restarted, becoming the first boiling-water reactor — the reactor type used at Fukushima Daiichi — to return to operation anywhere in Japan since 2011.
Why it matters: Onagawa’s plant actually withstood the 2011 tsunami and served briefly as an evacuation shelter. Its restart became one of the most symbolically significant of Japan’s entire programme, given both the reactor type and the location.
New Reactors Add Over 7 GW Worldwide New Build
What happened: More than 7 gigawatts of new nuclear capacity came online globally during 2024, with large reactors completed in China, France, India, the United Arab Emirates and the United States.
Why it matters: This is the “new build” strand of the comeback, distinct from Japan’s restarts — new nuclear capacity is genuinely being added, not just brought back from suspension.
COP28 Nuclear Tripling Declaration Signed Policy
What happened: More than 20 countries, including the U.S., France, Japan, South Korea and the UK, launched a declaration at COP28 backing the goal of tripling global nuclear energy capacity by 2050 from a 2020 baseline.
Why it matters: This was the clearest signal yet that nuclear had shifted from an accident-risk-only framing to a climate-and-energy-security framing at the multilateral level. The IEA later reported the coalition had grown to more than 40 countries.
Germany Shuts Its Final Three Reactors Exit Complete
What happened: Germany shut down its last three operating reactors, completing the nuclear phase-out it accelerated in the immediate aftermath of Fukushima.
Why it matters: Germany’s exit is the clearest counter-example to any “everyone is coming back to nuclear” narrative. Unlike Belgium or South Korea, Germany has not reversed this decision.
South Korea Reverses Its Nuclear Phase-Down Policy Reversal
What happened: A new South Korean administration reversed the previous government’s policy of gradually reducing reliance on nuclear power, restoring nuclear to the centre of national energy strategy.
Why it matters: South Korea was one of the clearest post-Fukushima phase-down cases to fully reverse, resuming both domestic reactor construction and nuclear technology exports.
Belgium Agrees to Extend Doel 4 and Tihange 3 by 10 Years Extension
What happened: The Belgian federal government decided to keep its two newest reactors, Doel 4 and Tihange 3, operating for an additional 10 years instead of closing them under the country’s 2003 phase-out law — the agreement with Engie was formally finalised in February 2025, with the reactors due back online in November 2025.
Why it matters: This is a lifetime extension, not a restart of a suspended reactor — but it is a direct reversal of a legally mandated phase-out, driven by the same energy-security shock as South Korea’s policy reversal.
Russia Invades Ukraine Catalyst
What happened: Russia’s invasion of Ukraine disrupted European gas supplies and sent energy prices sharply higher, forcing governments to reassess dependence on imported fossil fuels.
Why it matters: This is the single event most directly linked to the 2022 wave of nuclear policy reversals in Belgium and South Korea, and to Japan’s own more assertive restart language that year.
Sendai Unit 1 Restarts — Japan’s Restart Era Begins First Restart
What happened: Sendai Unit 1 became the first Japanese reactor to restart under the stricter safety standards introduced by the newly created Nuclear Regulation Authority, after more than two years with zero reactors operating nationwide.
Why it matters: This marked the actual start of Japan’s restart programme, three and a half years after the Fukushima accident and after a complete overhaul of the country’s nuclear regulator.
Japan Builds a New Regulator, Then Returns to Zero Reset
What happened: Japan established the Nuclear Regulation Authority to replace weaker pre-Fukushima oversight, and briefly restarted Ohi Units 3 and 4 to ease electricity shortages — before those reactors shut again for inspection, returning Japan to zero operating reactors by September 2013.
Why it matters: Any reactor wanting to return after this point had to pass the NRA’s new, much stricter requirements covering earthquakes, tsunamis, backup power and severe-accident response — the regulatory foundation every later restart, including Kashiwazaki-Kariwa, had to clear.
Japan Reaches Zero Operating Reactors Collapse
What happened: With Tomari Unit 3’s shutdown, Japan had zero operating nuclear reactors for the first time in decades, as the rest of the fleet had progressively gone offline for inspections and safety reviews following Fukushima.
Why it matters: Before Fukushima, nuclear supplied roughly 30% of Japan’s electricity. Losing all of it at once forced a rapid shift to LNG, coal and oil imports, reshaping Japan’s energy economics for over a decade.
The Fukushima Daiichi Accident Origin
What happened: A magnitude-9.0 earthquake and subsequent tsunami knocked out power and cooling at Fukushima Daiichi, causing reactor core damage, hydrogen explosions and a rating of INES Level 7 — the same top category as Chernobyl.
Why it matters: This single event triggered Japan’s fleet-wide shutdown, Germany’s accelerated phase-out, Switzerland’s long-term policy shift, and a global regulatory reset whose safety requirements still govern every restart discussed in this timeline.
Country by Country: Who Restarted, Extended, Built or Exited
The same accident produced at least four different national responses.
Japan
Zero reactors by 2013; restart era began 2015; 15 reactors back online by February 2026, with Kashiwazaki-Kariwa 6 reaching commercial operation in April.
Germany
Accelerated its phase-out immediately after Fukushima; shut its final three reactors on 15 April 2023. No reversal since.
Belgium
Reversed a legal phase-out mandate in March 2022; agreed a 10-year extension for Doel 4 and Tihange 3, finalised February 2025.
South Korea
Reversed a nuclear phase-down policy in 2022; resumed reactor construction and nuclear technology exports.
United States
Large existing fleet receiving lifetime extensions; several projects explore returning previously closed reactors to service, partly driven by AI data-centre demand.
China
The centre of global new-build activity; about half of global nuclear capacity currently under construction is in China.
France
Kept its nuclear-heavy grid throughout; combines lifetime extensions of its existing fleet with a new-build programme.
Taiwan
Shut its last reactor in May 2025, becoming nuclear-free; by March 2026 the government had opened a process that could lead to restarting two closed plants.
Restart, Extension, New Build: Not the Same Thing
Headlines often collapse all three into “nuclear comeback.” They involve very different costs, timelines and risks.
| Type | What it means | Typical timeline | Example |
|---|---|---|---|
| Restart | A suspended reactor with an existing licence is brought back online after regulatory review | Years per reactor, plus court/political delay | Japan, Sendai 1 to Kashiwazaki-Kariwa 6 |
| Lifetime extension | An operating reactor’s licence is extended past its originally planned retirement date | Negotiated in advance of retirement | Belgium, Doel 4 & Tihange 3 |
| New build | A newly constructed reactor enters commercial operation for the first time | A decade or more from construction start | Vogtle Unit 4, Georgia, U.S. |
Six Reasons Reactors Are Coming Back
No single cause explains the trend — these six forces are compounding.
The Drivers Behind the Comeback
- Energy security: Russia’s 2022 invasion of Ukraine showed how quickly imported energy can become expensive or politically unreliable.
- Climate targets: Nuclear generation produces electricity with very low operational carbon emissions, and countries pursuing net-zero goals are weighing the cost of losing existing low-carbon capacity.
- Rising electricity demand: AI data centres, electric vehicles, heat pumps and industrial electrification are all adding load that needs new generation.
- Existing infrastructure is valuable: A suspended reactor already has grid connections, land, trained staff and licensing history — often cheaper to restart than to build new capacity from scratch, if safety requirements can be met.
- Fossil-fuel price volatility: When gas and oil prices spike, nuclear plants reduce exposure to that volatility since fuel costs are a much smaller share of total generation cost.
- The post-Fukushima safety system itself: Ironically, the stricter regulatory framework built after 2011 gives governments a defensible basis to argue restarted reactors meet a higher safety bar than before the accident.
The Risks That Didn’t Disappear
A comeback in generation numbers doesn’t erase the underlying trade-offs.
The Global Nuclear Snapshot, End of 2025
Figures from the IEA’s Global Energy Review 2026 and The Path to a New Era for Nuclear Energy.
| Metric | Figure |
|---|---|
| Global operating nuclear capacity | ~420 GW |
| Countries with operating reactors | 30+ |
| Capacity under construction | ~78 GW across 15 countries |
| Share of new-build capacity located in China | About half |
| Reactors started since 2017 using Chinese/Russian designs | 94% |
| Countries with policies supporting expanded nuclear role | 40+ |
| Japan’s restarted reactors (as of Feb 2026) | 15, ~33 GW |
Editorial Note
This page distinguishes reactor restarts (Japan), lifetime extensions (Belgium, and parts of the U.S. fleet), and new construction (China, India, France, the U.S.) throughout — treating them as one undifferentiated “nuclear comeback” obscures very different costs, risks and timelines. Facts are compiled from IEA reports, World Nuclear News, TEPCO’s own press releases and other publicly available sources, and are current as of publication. Figures such as reactor counts and capacity under construction change as new plants restart, retire or connect to the grid; check the cited sources for the latest official numbers.
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Sources & further reading
Every dated entry above was checked against these references. Last reviewed 19 September 2026.
- IEA — Global Energy Review 2026: Technology, Nuclear
- IEA — The Path to a New Era for Nuclear Energy, Executive Summary
- World Nuclear News — Kashiwazaki-Kariwa 6 Resumes Commercial Operation
- World Nuclear News — Fresh Record Set for Nuclear Generation in 2025
- World Nuclear News — Reactor Closure Marks Taiwan's Nuclear Exit
- World Nuclear News — Deal Finalised for Belgian Reactor Restarts in November
- OECD NEA — Countries Launch Joint Declaration to Triple Nuclear Energy Capacity by 2050 at COP28
- World Nuclear Association — Nuclear Power in Japan