Japan’s decision to dump more than one million tonnes of treated radioactive water – equivalent to around 500 Olympic swimming pools – into the sea from the tsunami-ravaged Fukushima nuclear power plant has sparked much controversy.
The first water discharge is not expected for about two years, during which time the plant owner, Tokyo Electric Power (TEPCO), will filter the water, build the infrastructure and obtain regulatory approval.
Here are some questions and answers about the plan, which is expected to take decades.
What is the treated water?
Radioactive water has accumulated at the plant since the 2011 tsunami destroyed the plant’s electricity and cooling systems, triggering the worst nuclear accident since Chernobyl.
Some of it was used to cool the three damaged reactors, while the rest came from rain that fell on the contaminated site and groundwater.
An extensive pumping and filtration system called “ALPS (Advanced Liquid Processing System)” ensures that the molten uranium fuel rods stay cold and extracts tons of newly contaminated water every day, filtering out most of the radioactive elements.
The operator of the Tokyo Electric Power (TEPCO) plant has built more than 1,000 tanks to hold around 1.25 million tonnes of treated water at the site, but they will be full by the second half of 2022.
In 2018, the company admitted it hadn’t filtered all of the hazardous material out of the water, although it had said for years that it had been removed.
What radioactive isotopes are found in water?
The ALPS process removes most radioactive isotopes to ensure wastewater meets international safety guidelines.
But it cannot remove from it, including tritium, a radioactive isotope of hydrogen.
Tritium is considered relatively harmless because it does not emit enough energy to penetrate human skin. But once ingested, it can increase cancer risk, according to a Scientific American magazine article in 2014.
The half-life of tritium – the time it takes for half the atoms of a radioactive isotope to decay – is 12.3 years. In humans, its biological half-life is estimated at 7 to 10 days.
How will the water be released?
The government says the publication process will meet international standards and has been approved by the International Atomic Energy Agency (IAEA).
Water containing tritium is regularly released from nuclear power plants around the world and the release of Fukushima water into the ocean is supported by regulatory authorities.
“The discharge into the ocean is done elsewhere. It is not something new. There is no scandal here, ”said IAEA Director General Rafael Mariano Grossi.
Government spokesman Katsunobu Kato said the dilution would reduce tritium levels to well below standards set nationally and by the World Health Organization (WHO) for drinking water, and will take place under IAEA supervision.
Why is the plan controversial?
Many people have questioned TEPCO’s plans as there is a high level of distrust of the company after years of leaks, spills, equipment malfunctions and breaches of safety.
Environmental groups such as Greenpeace, which opposes nuclear power, say that radioactive material like carbon-14 that remains in water can “be easily concentrated in the food chain.”
They allege that doses accumulated over time could damage DNA and want to see the water stored until technology is developed to improve filtration, accusing TEPCO of taking “the cheaper option.”
Local fishing communities fear that years of working to convince consumers that Fukushima seafood is safe will be wiped out by the publication.
“The government’s message that the water is safe is not reaching the public, that’s the huge problem,” an official from the Fukushima Fishermen’s Union Association told AFP news agency.
He said business partners warned they would stop selling their products and consumers said they would stop eating Fukushima seafood if the water was released.
“Our efforts over the past decade to restore the fishing industry will be in vain.”
China has also expressed concern over the plan, calling it “highly irresponsible.”
South Korea continues to impose restrictions on Japanese products in the wake of the Fukushima disaster, and a foreign ministry spokesman said the country was “seriously concerned” about the move to move from there. ‘forward with the release of water, which she said “could have a direct and indirect impact on the safety of our staff and their environment”.
The city councils of Busan and Ulsan, South Korean towns near the sea, have called for the liberation plan to be abandoned.
What about Fukushima seafood?
The government says radioactive elements in water are well below international standards, pointing out that wastewater is routinely discharged from nuclear power plants elsewhere.
Even releasing all stored water in a single year would produce “no more than a thousandth of the impact of natural radiation exposure in Japan,” the Foreign Ministry said in a response to a report. of ONU.
For food, Japan sets a national standard not exceeding 100 becquerels of radioactivity per kilogram (Bq / kg), against 1,250 Bq / kg in the European Union and 1,200 in the United States.
But for Fukushima’s products, in an effort to gain consumer confidence, the level is even lower, at only 50 Bq / kg. Hundreds of thousands of food products have been tested in the region since 2011.
What are the scientists saying?
Michiaki Kai, a radiological risk assessment expert at the Japanese University of Nursing and Health in Oita, said it was important to control the dilution and volume of the water being released.
But “there is a consensus among scientists that the impact on health is minimal,” he told AFP.
However, “we cannot say that the risk is zero, which is causing controversy”.
Geraldine Thomas, President of Molecular Pathology at Imperial College and radiation expert, said tritium “poses no health risk – especially considering the Pacific Ocean dilution factor.”
She said carbon-14 was not a health risk either, arguing that chemical contaminants in seawater such as mercury should be of concern to consumers “more than anything from the Fukushima site.” .
“I would have no hesitation” eating Fukushima seafood, she added.