Analysis: The legacy of the Fukushima nuclear disaster

§ Nuclear heat

When the earthquake hit, there were 11 reactors operating at four nuclear power plants in the affected Miyagi region.

These were the four reactors at Fukushima Daini, three reactors at Onagawa, one reactor at Tokai, and three reactors at Fukushima Daiichi. Daiichi’s three other units were not in operation at the time, with the fourth reactor down for refuelling.

All the units shut down automatically when the quake hit — but this is not enough to stop a plant from generating heat. Even after a plant has shut down it continues to produce “decay heat”, which amounts to 6-7% of the heat power produced by a fully operating plant.

This heat quickly diminishes. But to avoid nuclear meltdown, it is imperative that the reactor is kept cool in the first day or so after the reaction has stopped taking place.

This was what happened at the eight reactors sited at the Daini, Onagawa and Tokai plants, which were able to access the back-up power needed to run the cooling process.

At Fukushima Daiichi, however, the process failed. The result was the largest nuclear disaster since the Chernobyl accident in 1986 in what is now Ukraine.

§ A seismic country

Japan is located in one of the most seismic areas in the world. It has a long history of dealing with earthquakes.

The Sandai-jitsuroku is an historical Japanese text that contains the following passage:

What it describes is the Jogan tsunami, named after Japan’s emperor at the time, which hit northeast Japan on 13 July, 869 AD. It was in the same region that would be struck again by the Great East Japan Earthquake in 2011.

A study of the event found that “gigantic tsunamis” hit Japan every 800 to 1,100 years. With unfortunate accuracy, the scientists concluded:

This is not the only evidence of abnormally large tsunamis hitting the Japanese coast. One compilation of historical tsunamis lists 12 tsunamis since 1498 of more than 10 metres. Six of these were more than 20 metres.

The Fukushima Daiichi nuclear plant, located on the coastline, was designed to withstand a 5.7m tsunami. The one that struck the plant was around 15m high.

The fact that Fukushima was obviously ill-equipped to withstand a force of this nature has led some experts to conclude that the nuclear meltdown that followed was preventable.

§ Radiation is released

The sequence of events that took place over the following days would leave a scar on Japan’s people, environment and climate policies that is still present today.

The central challenge was keeping the reactors cool. Failure to do this means that the nuclear fuel can melt and, in a worst-case scenario, burn through the containment vessel and subsequent barriers, releasing radiation to the outside world. Experts are still uncertain where the melted nuclear fuel at Fukushima has gone.

To cool many types of nuclear reactor, you need power. With its reactors shut down, and the grid connection damaged, the Fukushima plant had to rely on backup diesel generators.

These were located in the basement of the turbine buildings, while the sea pumps required to cool them were located just four metres above sea level. When the tsunami hit, these were inundated with water, and could no longer operate. The batteries that were supposed to provide power in the case of a blackout were also rendered inoperable by flooding.

One by one, the three reactors lost their ability to cool, which caused the nuclear fuel to melt.

Radiation was subsequently released into the environment over the coming days, both on purpose and by accident, as radioactive steam was released into the air, either through leaks or in an attempt to reduce the rising pressure.

Further radiation was released by explosions caused by the release of hydrogen in the four days following the tsunami. Radioactive water also leaked into the Pacific ocean.

§ The human impact

The earthquake and the tsunami that followed caused a humanitarian disaster in Japan. More than 19,000 people were killed, and 465,000 were evacuated. Damage also cost the national economy hundreds of billions of dollars.

The nuclear disaster at Fukushima has also caused a great deal of human suffering, much of which will continue to unfold in the years to come. Around 150,000 people living nearby the damaged reactors were evacuated because of the threat of radioactivity. This in itself has caused mental strain and evacuation-related deaths, according to reports.

Accounts of the physical impact caused by the released radiation vary.

A UN report released in 2013 says that there were no radiation-related deaths among the workers and public in the surroundings following the disasters, and there is not expected to be any increase in radiation-caused illnesses.

A report by Greenpeace released this month, however, says that the impact of Fukushima will continue to impact nearby ecosystems for centuries.

§ Japan’s energy supply

Another area where Fukushima has had a lasting impact is on Japan’s energy mix.

Japan has little in the way of domestic fossil fuel resources. In 1973, the government made the development of nuclear power a national strategic priority, off the back of the global oil price shock, and invested heavily in a major nuclear construction programme.

Before Fukushima, nuclear power represented almost 30% of Japan’s power generation, and was one of its cheapest sources of electricity. In comparison, 25% of electricity was provided by coal, 29% by liquified natural gas (LNG), 8% by oil and 10% by renewables.

It also saw nuclear power playing a growing role in its future energy mix. The government had planned to increase its share to 41% by 2017, and 50% by 2030, at the same time as reducing its emissions. Fukushima changed these aspirations almost overnight.

Before the earthquake and tsunami hit, Japan had 54 nuclear reactors, with a capacity of around 47 gigawatts (GW). It was the third largest nuclear power generator after the US and France. Over the following years, this dwindled to nothing.

Japan lost 10GW of nuclear capacity instantly when the earthquake hit, shutting down facilities at Fukushima, Onagawa and Tokai. The serious damage to the Fukushima Daiichi plants in the accident meant that all six of its reactors were officially decommissioned.

The Japanese government then proceeded to disable its nuclear fleet one-by-one. As the plants came offline for general maintenance, tougher safety rules and a hostile public meant that they were not restarted. May 2012 marked the first time that Japan was generating no nuclear power for the first time in 40 years.

§ Japan reneges on climate targets

Japan was left with a gaping hole in its energy mix. In the following years, this was largely plugged with energy efficiency savings and fossil fuels, primarily liquified natural gas and oil. Coal also started playing a larger role in 2013, as more capacity came online.

This switch wasn’t cheap. Japan’s limited domestic resources meant that a farewell to nuclear precipitated a shopping trip for fossil fuels abroad. For instance, Japan’s imports of LNG rose by more than 25% between 2010 and 2013. Coal imports have also risen, from 185m tonnes in in 2012 to 191m in 2013.

In the three years following the disaster, Japan spent around $270bn on fossil fuel imports — an increase of around 58% on previous years. The country found its $65bn trade surplus declining and then reversing. By 2013, it had a deficit of $112bn.

In its 2014 budget, the government set aside $3bn for energy, including energy conservation and renewable energy. The reason it cited was not climate change, but high energy costs, which it said had risen by about 25% for households and 40% for industry since Fukushima.

Japan’s reputation on climate change was another thing that was arguably damaged by the earthquake and all that followed. With the loss of low-carbon nuclear power and the increase in fossil fuels, Japan’s greenhouse gas emissions predictably spiked.

At 1.2% above 2012 levels, and 10.8% higher than 1990 levels, Japan’s emissions in 2013 were its highest to date. In 2014, they dipped by 3% due to decreasing energy consumption and improving carbon intensity, the government said.

This increase in emissions sat uncomfortably alongside UN targets set by the Japanese government, including a 6% reduction of emissions compared to 1990 levels by 2012, and a reduction of 25% by 2020.

Japan consequently revised its emissions pledge in November 2013. Instead of reducing its emissions on 1990 levels, the government announced that it would instead cut them by 3.8% on 2005 levels — which amounts to a 3.1% increase on 1990 levels.

The country has also come under fire for its plans to significantly grow its fleet of coal-fired power plants, putting it at odds with many of its G7 compatriots, including the UK, where the direction is towards a phase-out of coal. Japan has plans to construct around 50 new coal plants, with a capacity of more than 30GW, compared to its current 41GW.

The latest climate target that Japan has submitted to the UN, as part of last year’s Paris climate change agreement, accommodates this expansion. Carbon Brief analysis shows that Japan’s goal would allow it to grow its coal consumption by 30% in the next 15 years, at the same time as pledging to reduce emissions 26% by 2030, compared to 2013 levels.

§ Goodbye, nuclear renaissance?

Ten years before Fukushima, many had started to hope that the time had come for a nuclear renaissance. Fears over nuclear safety following the disasters at Chernobyl and Three Mile Island meant that new nuclear capacity plummeted in the 1990s.

But, by the next decade, memories were fading and there was widespread pressure to reduce carbon emissions. Some countries started warming to the idea of constructing a new, state-of-the-art fleet of nuclear reactors.

Finland led the way in Europe, with a new breed of nuclear technology at its proposed plant at Olkiluoto. In the US, George W Bush launched a nuclear program in 2002, with proposals for 36 reactors subsequently coming forward. By 2006, the UK had also committed to a new nuclear program.

But the meltdown at Fukushima quelled this excitement. Despite the fact that there were no deaths immediately linked to the release of radiation at Fukushima, some have claimed that media coverage of the meltdown eclipsed the 19,000 deaths caused by the tsunami.

“It is an invisible hazard, mysterious and not understood, associated with dire consequences such as cancer and birth defects. It feels unnatural,” the BBC attempted to explain at the time.

Fukushima had a direct impact on many governments that had previously been enthusiastic about the prospect of a nuclear rebirth. Antony Froggatt, a senior research fellow at Chatham House, tells Carbon Brief:

While this reawakening of the public’s fear of nuclear power may alone not have been enough to throw the nuclear renaissance back into the dark ages, economic considerations delivered an additional blow.

Peter Bradford, a former member of the US Nuclear Regulatory Commission, and now an adjunct professor at Vermont Law School, tells Carbon Brief:

§ Looking to the future

Despite Fukushima and the increasing viability of alternative sources of energy, including renewables and shale gas, the embers of the nuclear renaissance burn on.

In its long-term energy strategy, Japan outlines a future with a clear role for nuclear, with its re-opened reactors providing between 20-22% of its power by 2030, even as campaigners have called for a transition to renewable energy and public opposition remains high.

Meanwhile, it envisages renewables providing 22-24% of its power — while coal would get a 26% slice of its future mix.

“It learned nothing from the Fukushima disaster and it’s moving from nuclear disaster to climate disaster,” Naoyuki Yamagishi of WWF-Japan tells Carbon Brief.

Other countries are also pushing on with nuclear plans. In the UK, the new reactor proposed at Hinkley Point in Somerset has at least one enthusiastic supporter in the Treasury. Recent statistics released by China showed that the country’s nuclear generation capacity increased by 30% in 2015.

Among environmentalists, the role for nuclear power in a low-carbon future continues to divide. And while some governments are vigorously pursuing a new nuclear age, others have turned away from its perceived risks, expense and complications.

When the tsunami slammed into the Fukushima nuclear power plant, it also began to topple a domino chain of climate change, energy and fear. Five years on, these dominoes continue to fall.

Main image: A view of a building of the tsunami-crippled Fukushima daiichi nuclear power plant from bus window, June 12 2013.