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Fukushima nuclear disaster and water release
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The Japanese government said releasing the contaminated water would allow the plant to be decommissioned. Photo: Kyodo

Explainer | Why is Japan going to dump radioactive water from Fukushima nuclear plant in the sea? What are the risks and is there an alternative?

  • Decision to release waste water from the nuclear plant hit by a devastating earthquake and tsunami in 2011 has triggered a backlash from neighbouring countries
  • Many scientists believe it is the only realistic option, but governments, fishing groups and environmentalists have also expressed concern

Japan’s decision on Tuesday to release treated radioactive water from the damaged Fukushima nuclear plant into the sea was met with fierce opposition from its neighbours, including China, as well as the local fishing industry. 

Prime Minister Yoshihide Suga said ocean release was the most realistic option for Fukushima’s recovery, a decade after a massive earthquake and tsunami triggered a nuclear meltdown in March 2011. 

Here we examine some of the biggest questions raised by the decision.

What exactly does the waste water contain? 

Following the 9.0-magnitude earthquake on March 11 2011, three out of the six reactors at the Fukushima Daiichi Nuclear Power Plant overheated. The damage to the reactors meant that the water used to cool them down became contaminated.

A protestor holds a slogan which reads “don’t release the radioactive water” at a rally outside the prime minister’s office in Tokyo. Photo: AFP

Although most of the radioactive elements can be filtered out by a system known as the ALPS (Advanced Liquid Processing System), tritium, a mildly radioactive form of hydrogen, cannot be removed.

Nigel Marks, an associate professor of physics and astronomy at Curtin University in Perth, said: “It takes around 60-100 years to completely convert into harmless helium. In the spectrum of radioactive elements, tritium is at the mild end.”

China warns of action over Japan’s decision to dump radioactive Fukushima water into the sea

But some other radioactive substances might still be present in the waste water. “There is a long list of other radioactive substances that could be present like caesium-137 and strontium-90. They may be present at high levels,” said Luk Bing-lam, chairman of The Hong Kong Nuclear Society.

Greenpeace suggested carbon-14, a radioactive isotope of carbon, might also remain in the water.

Are there any health concerns? 

Most scientists agree that the presence of tritium is not a major concern.

“The health impact will be almost zero,” said Marks. “We are surrounded by radiation in our daily life, and this release will not affect humans, marine life or the ocean itself.”

Luk said it would be further diluted by seawater. “Tritium can cause cancer, the same as other radioactive substances,” he continued. “But the dosage is so low that it is not likely to cause cancer in the long term.

“The biological half-life of tritium is around 10 days. [Which means] the tritium will not accumulate in our body over a long period of time.”

02:58

Japan’s plan to release radioactive water from Fukushima nuclear plant into sea sparks outrage

Japan’s plan to release radioactive water from Fukushima nuclear plant into sea sparks outrage

The Japanese government plans to dilute the tritium to less than 1,500 becquerels per litre, the unit used to measure radioactivity. 

That is about a seventh of the limit recommended in drinking water by the World Health Organization’s guidelines. Or one-40th of the concentration allowed under Japanese safety standards. 

Is Japan downplaying the danger Fukushima water poses to human health?

But Luk said there was a need to monitor the other radioactive elements. He said that if caesium-137 and strontium-90 are present, they could have a much greater impact on health.

He warned that stringent monitoring by the international community was required to ensure the isotopes are not present at high levels.

Why is Japan doing this?

Space to store the waste water is running out. Currently about 1.25 million tonnes of radioactive water are being stored at Fukushima and the site is expected to reach full capacity next year, according to the plant’s operator Tokyo Electric Power Company (Tepco). 

Tepco wants to decommission the plant between 2041 to 2051, but it cannot move forward with the plans if more storage tanks have to be built to contain the waste water.

02:36

Meet the man saving cats abandoned in Fukushima nuclear zone for a decade after the disaster

Meet the man saving cats abandoned in Fukushima nuclear zone for a decade after the disaster

Suga said, “We have no choice but to take on the waste water issue, as we need to proceed with decommissioning of the nuclear reactors.”

Marks said advanced purification technologies have already removed the most dangerous radioactive material and the tritium mixture “has to go somewhere”.

What is the release process? 

Under the plan adopted by Japanese ministers on Tuesday, Tepco will start discharging the radioactive water in two years’ time. The gradual release of water will take about 30 years and is expected to end before the decommissioning process is complete. 

The plan has been endorsed by the International Atomic Energy Agency (IAEA). “The water disposal method Japan has chosen is both technically feasible and in line with international practice, even though the large amounts of water makes it a unique and complex case”, said IAEA director general Rafael Mariano Grossi.

“Controlled water discharges into the sea are routinely used by operational nuclear power plants in the world and are done under … strict safety and environmental standards,” Grossi said in a video published on the IAEA’s website.

Storage tanks holding the contaminated water. Photo: EPA-EFE

Who opposes the plan? 

Japan’s decision drew swift condemnation from some of its neighbours and environmental groups.

China blasted the Japanese government for being “extremely irresponsible”, saying it had not considered the health of people in neighbouring countries, which had not been consulted about the plan. Warning that it might take action in response, Beijing called on Tokyo to reverse the decision.

South Korea expressed “strong regret” and asked for further details about how the water will be treated and its safety is verified. The country also plans to strengthen radiation checks on imported foods. 

China raises concerns over Japan’s plan to dispose of Fukushima water

Greenpeace Japan accused the government of disregarding human rights and interests of the people in Fukushima and in the wider Asia-Pacific. 

Japan’s local fishing industry also opposes the release, worried that consumers might shun their seafood as a result.

Taiwan’s government and fishing industry also expressed concern about the plans.

Is there an alternative? 

The other option is simply to wait until the waste water has evaporated, according to the Japanese economy, trade and industry ministry. Both methods were seen as technically feasible by the IAEA.

But Marks from Curtin University said releasing it at sea was “the only sensible option”. He said evaporation is “not controlled as the moisture could go anywhere”.

“From a technological point, there are excellent separation/purification schemes for many radioactive elements, but there is nothing that works for tritium on an industrial scale,” said Marks. 

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