Tanks containing treated radioactive wastewater at the Fukushima Daiichi nuclear power plant. Japan is looking to ditch efforts to lessen its reliance on nuclear power, despite the Fukushima disaster.

More than a decade after the triple meltdown at the Fukushima Daiichi power plant, Japan is again turning to nuclear power as it struggles to reach its emissions targets and bolster its energy security.

In a draft strategic energy plan due to be approved by the cabinet this month, the trade and industry ministry signalled it was ditching attempts to lessen Japan’s reliance on nuclear power in the wake of the Fukushima disaster – the world’s worst nuclear accident since Chornobyl 25 years earlier.

The document dropped a reference to “reducing reliance” on nuclear energy that had appeared in the three previous plans, and instead called for a “maximisation” of nuclear power, which will account for about 20% of total energy output in 2040, based on the assumption that 30 reactors will be in full operation by then.

The plan envisages a share of between 40% and 50% for renewable energy – compared with just under a third in 2023 – and a reduction in coal-fired power from the current 70% to 30-40%.

The push to restart reactors idled since the plant was struck by a tsunami triggered by a magnitude-9.0 earthquake has been condemned by climate campaigners as costly and dangerous.

“Nuclear plants are not where the Japanese government should be investing its money,” says Aileen Smith, executive director of the Kyoto-based group Green Action. “Many nuclear plants are old, and the technology they use is even older. The costs of retrofitting are high, so even operating existing plants is no longer commercially viable.”

Ageing reactors – those at least 40 years old – make up 40% of those in operation around the world, but only 20% in Japan, according to a recent study by the Yomiuri Shimbun. In the US, by contrast, 64 of the country’s 94 reactors – 68% of the total – will have been operating for at least 40 years by the end of the year, the newspaper added.

But unlike many other countries that use nuclear power, Japan is vulnerable to powerful earthquakes and tsunami of the kind that wrecked Fukushima Daiichi.

“Earthquakes are the biggest danger, and they could strike old or new reactors,” Smith says. “The more reactors you have in operation, the greater the risk. It’s as simple as that. Retrofitting would mean spending huge sums of money on all those old reactors when the government could instead be putting its money into renewables.”

Officials say reactors will need to be restarted if Japan is to meet an expected increase in demand for power, partly driven by AI-related data processing centres and semiconductor factories, as well as achieving net zero by the middle of the century.

But campaigners say government plans to persist with ageing reactors would leave Japan vulnerable to another major accident. “Ageing in nuclear power plants is a highly complex subject that has the potential to fundamentally challenge the safety and integrity of a nuclear reactor,” says Hisayo Takada at Greenpeace Japan.

“As reactors operate, they are subject to enormous pressures and temperatures, all of which contribute to major stresses. The prospect of Japan operating ever more reactors to 60 years and beyond is evidence of a major experiment being conducted on the country. It has the potential to be catastrophic.”

Instead, Takada adds, the government should do more to promote renewables.

“The climate crisis demands the rapid decarbonisation of society, with energy and the production of electricity a priority,” she says. “The only technologies that exist today that can deliver on the short timescale we face with the climate crisis are improved energy efficiency and expanding renewable energy.”

The triple meltdown at Fukushima Daiichi shook Japan’s confidence in nuclear power. Before the disaster, 54 reactors were in operation, supplying about 30% of the country’s electric power. Just 14 reactors have been restarted, while others are being decommissioned or awaiting permission to go back into service.

The accident caused a radiation leak, forcing more than 160,000 people living nearby to flee their homes and turning entire communities into ghost towns. Decommissioning the plant is expected to cost trillions of yen and take four decades.

The post-Fukushima closures of reactors forced Japan to rely more heavily on imported fossil fuels; it is now the world’s second-largest importer of liquefied natural gas after China and the third-largest importer of coal.

In the 14 years since, utilities have restarted 14 reactors, including one in the region destroyed by the 2011 tsunami, despite opposition from local residents. From June this year, nuclear plants can remain in operation beyond the previous limit of 60 years provided they undergo safety upgrades.

Last year the No 1 reactor at Takahama nuclear plant in central Japan became the first to receive approval to operate beyond 50 years. Four reactors have already been operating for more than 40 years, with three more due to reach the milestone this year.

Sections of the media have reacted with horror at the prospect of a significantly bigger role for nuclear, and accused politicians of hypocrisy.

Noting that the prime minister, Shigeru Ishiba, had promised to try to bring nuclear-power generation “to as close to zero as possible” during his campaign for the leadership of the ruling party last autumn, the Asahi Shimbun said: “If the government’s abrupt and irresponsible about-face in the draft plan isn’t an act of betrayal against the public, what is?”