In a single afternoon, a billion-dollar industry was brought to its knees.
On March 11, 2011, a magnitude-9.0 earthquake sent a tsunami hurtling towards Japan's east coast, killing 20,000 people, wiping out 120,000 buildings and sparking a partial meltdown at the Fukushima Daiichi nuclear power plant.
The meltdown and mass evacuation triggered a global panic, with countries as far away as Germany vowing to shut their nuclear plants.
Japan also switched off its reactors in the wake of the disaster.
But as the years passed and new crises emerged, nuclear power started to make a comeback.
How global fears helped nuclear make a comeback
Prior to the Fukushima disaster, Japan had 54 nuclear reactors providing nearly 30 per cent of the nation's energy.
Only 14 of those have been switched back on, with nuclear providing less than 9 per cent of power in 2023, according to the International Energy Agency.
But the Japanese government wants to rapidly expand the industry and build the "next generation" of reactors.
Its latest Strategic Energy Plan has dropped calls for less reliance on nuclear power and has set a target for nuclear to provide a 20 per cent share of the nation's grid by 2040.
Climate change, energy security, rising demand and industry encouragement are all helping push nuclear back onto the agenda.
The invasion of Ukraine and subsequent disruption of global energy markets also helped highlight the risk of Japan's heavy reliance on imported fossil fuels, according to visiting researcher at Tokyo's Institute for Future Initiatives, Parul Bakshi.
"Almost 90 per cent of fuel is imported," she said.
"So while Japan is not heavily reliant on Russia for gas … Japan is re-evaluating how it perceives energy security."
Japan would still need to import the uranium from countries like Australia to power its nuclear plants. However, much less material is required compared to other fossil fuels like coal and gas.
Green tech gives nuclear a second chance
As Japan seeks to reinforce its power supply, the country is bracing for a boom in demand due to the rapid increase of data centres.
These power-hungry facilities are essential for operating growth industries like cloud computing and artificial intelligence.
Hokkaido Electric said it could meet this growing demand by restarting its reactors while Google-owner Alphabet has thrown its support behind nuclear power to help decarbonise its sprawling technological empire.
Chair of the Atomic Energy Society of Japan Dr Hiroyuki Oigawa said the global support for net zero and energy security concerns were "big factors for changing the people's mind" about nuclear power.
"But most Japanese people will not forget the Fukushima accident," he said.
"We have a responsibility to continually enhance the safety of nuclear power and make every effort to restore Fukushima."
Will nuclear live up to its green credential?
Nuclear advocates often argue that because these power plants don't produce greenhouse gases during operation, they are essential in the fight against climate change.
But these green credentials are challenged by those who point out that nuclear plants require huge volumes of water, produce toxic waste and are vulnerable to natural and geopolitical disasters.
Anti-nuclear advocate Aileen Mioko Smith says nuclear power ultimately delays climate action, as seen after the signing of the world's first emissions reduction treaty, The Kyoto Protocol, in 1992.
"That would have been an excellent opportunity to end nuclear power and really work on renewables, efficiency and conservation," she said.
"Instead, the government said, no, we're going to build 21 new nuclear power plants by 2010."
"Only eight reactors got built and, in the meantime, we lost a whole decade working on more assertive use of renewables."
Alongside the long-term delay to climate action, Ms Mioko Smith has been raising the alarm about the short-term impact of nuclear accidents since the 1980s.
"Our last warning was when there was an earthquake at the largest nuclear power plant in the world, Kashiwazaki-Kariwa (in 2007)," she said.
"The local people had been fighting to stop this huge plant ever since the mid-1970s and they went to Tokyo to try to warn that the next time will be serious.
"So when Fukushima hit, my first reaction was, here it comes, we weren't able to stop it."
Legal battles to stop the reactor restarts
Today, Ms Mioko Smith and her advocacy group Green Action is one of many organisations who have launched lawsuits against almost every single reactor restart.
"We have won multiple lawsuits, including injunctions, but then losing in appellate court," she said.
"It's a struggle, but I think that it's successful in delaying restarts."
Energy policy researcher Florentine Koppenborg wrote a book about how the Fukushima disaster impacted the politics of safety governance and said activism had become much more organised.
"There have always been lawyers fighting nuclear power plants," she said.
"But what they did after the accident is they formed an association to cooperate nationwide and to share the lessons learned, to look at what works, what doesn't."
As advocates work with local citizens, some communities struggling with population and economic decline are calling for their reactors switched back on to help rejuvenate their region.
Tougher safety standards are breaking the business
While advocates fight in court, power companies are often battling regulators.
In the wake of Fukushima, Japan established an independent safety authority to set tougher standards and oversee the restarts.
This has created headaches for power companies, who now must deal with an independent regulator rather than Japan's pro-nuclear Ministry of Economy, Trade and Industry.
Before being granted approval for a restart, power companies need to complete an array of safety upgrades, from backup power supplies to massive tsunami walls.
Ms Koppenborg said many nuclear power plant operators "completely underestimated" the cost of meeting the new standards.
"Safety costs have just skyrocketed, something that is of course impacting the economic viability of nuclear power as a business," she said.
"The government still has a pro-nuclear policy line.
"But the ones that are bearing the brunt of the costs, the operators, some of them are silently exiting the nuclear power business."
What about the nuclear reactors of the future?
These economic and legal challenges help explain why Japan's nuclear industry has been slow to bounce back after Fukushima.
Of the 54 nuclear reactors operating at the time of the disaster, 27 have been decommissioned or have not applied for a license to restart.
Meanwhile, Japan's government hopes power companies will invest in a new generation of reactors.
Five key technologies have been identified, from small modular reactors, designed to be fast and cheap to construct; to high temperate gas cooled reactors, to power energy-intensive industries like steel production.
Dr Oigawa said Japan was also collaborating with France and the United States on sodium-cooled fast reactors, which uses liquid metal rather than water for coolant.
"We have a (600 megawatt) experimental fast reactor in Joyo [in Kyoto], which is under modification to meet the new regulation," he said.
Can Japan meet its climate goals without nuclear?
As investment in new nuclear technology continues, experts say Japan is running out of time to meet its net zero goals.
Under the country's targets for 2040, 40 to 50 per cent of energy will come from renewables, 20 per cent from nuclear and the rest from thermal sources, like coal, oil and gas.
If Japan fails to meet its targets on renewables or nuclear, the country will likely be forced to burn fossil fuels to make up the shortfall.
Dr Koppenborg suspects the government keeps backing nuclear because "they simply lack a plan B".
"It's not a very politically sexy topic to say that the past decade of betting on nuclear power has not worked out," she said.
When it comes to renewables, Dr Oigawa said Japan's geography and limited land made it "challenging to make renewables available cheaply, safely and without being affected by the weather".
"At this moment, our stance is to use everything that is available with paying attention to price and domestic supply chain," he said.
But Ms Mioko Smith said if Japan wanted to tackle climate change, it needed solutions that were "fast, cheap and reliable".
"Fast means you can't be talking about new reactors that are a pie in the sky, know, 20, 30 years down the line," she said.
"That's just going to be too late."
