Japan plans to release more than 1 million metric tonnes of treated radioactive water from the Fukushima nuclear plant into the Pacific Ocean by the end of August. After years of debate, and despite a green light from the International Atomic Energy Agency (IAEA), the plan continues to stoke fears among the local population and in nearby countries.
Twelve years after the triple catastrophe – earthquake, tsunami, reactor meltdown – that struck the Fukushima Daiichi nuclear power station in 2011, Japan is preparing to release part of the treated wastewater from the stricken plant into the Pacific Ocean this month. A recent article from the daily Japanese newspaper Asahi Shimbun revealed the upcoming release without specifying a date.
The release of contaminated water by the Tokyo Electric Power Co. (TEPCO) has been on the cards since 2018 but it was repeatedly postponed until it finally received endorsement from the International Atomic Energy Agency in early July. After a two-year review, five review missions to Japan, six technical reports and five missions on the ground, the international nuclear watchdog said the discharges of the treated water were consistent with the agency’s safety standards, with “negligible radiological impact to people and the environment”. The green light, which cleared the path for the completion of the project, was greeted with scepticism by some members of the scientific community and with animosity by many local fishermen who fear that consumers will shun their products.
Storage capacities reaching their limit
On March 11, 2011, the three reactor cores of the Fukushima Daiichi nuclear power plant experienced a meltdown, leaving northeast Japan devastated and adding a nuclear emergency to the devastation caused by the earthquake and tsunami. Since then, massive quantities of water have been used to cool down the nuclear reactors’ fuel rods every day, while hundreds of thousands of litres of rainwater or groundwater have entered the site.
Japanese authorities initially decided to store the contaminated water in huge tanks, but are now running out of space. Some 1,000 tanks were built to contain what is now 1.3 million tonnes of wastewater. Japanese authorities have warned that storage capacities are nearing their limit and will reach saturation by 2024. The power plant is also located in a region with a high earthquake risk – meaning that a new tremor could cause the tanks to leak.
Read moreFukushima fallout: A decade after Japan's nuclear disaster
Filtering the contaminated water
To avoid such an accident, the Japanese government has decided to gradually discharge millions of tonnes of water into the Pacific Ocean over the next 30 years. The process is simple: the water is set to be released one kilometre away from the coast of Fukushima Prefecture via underwater tunnel.
Releasing treated wastewater into the ocean is a routine practice for nuclear plants all over the world. Water is usually made to circulate around a nuclear reactor to absorb heat, making it possible to trigger turbines and produce electricity. In the process, the water becomes loaded with radioactive compounds, but it is then treated before being released into the sea or rivers.
"In Fukushima, however, the situation is very different since it is a damaged plant,” said Jean-Christophe Gariel, deputy director in charge of health and the environment at France's Institute for Radiological Protection and Nuclear Safety (IRSN).
"This time, part of the stored water was poured directly onto the reactors in order to cool them,” Gariel added. “Unlike the water from our [French] nuclear plants, [theirs] became loaded with many radioactive compounds, known as radionuclides."
Before discharging the water into the sea, the challenge is therefore to remove most of the radioactive materials. To do this, Fukushima's operator, Tepco, uses a powerful filtration system called ALPS (Advanced Liquid Processing System). "This makes it possible to eliminate a large part of these radioactive substances, which are only present as traces," said Gariel.
“On the other hand, as in our own power plants, one component remains: tritium, which cannot be eliminated,” he added. This substance is routinely produced by nuclear reactors and released by power plants around the world. While it is considered relatively harmless, it is often blamed for increasing the risk of cancer. “To limit the risks even further, the water will be diluted in a large quantity of seawater to lower the concentration of tritium as much as possible,” Gariel explained.
During the most recent test of the water tanks in March, the Japan Atomic Energy Agency detected 40 radionuclides. After treatment, the concentration in the water was lower than accepted standards for 39 – all of them, except for tritium. The level of the latter reached 140,000 becquerels per litre (Bq/L) – while the regulatory concentration limit for release into the sea is set at 60,000 Bq/L in Japan. After the final dilution step, however, the tritium level was reduced to 1,500 Bq/L.
"To put it simply, while the water from the Fukushima reservoirs is more contaminated than the water from [French] power stations, after treatment and dilution, it is the same as anywhere else," said Jean-Christophe Gariel.
‘It's like diluting whiskey in Coke’
Yet these standards and figures must be nuanced and taken with caution, with set thresholds varying greatly from one country to another. For example, France sets its tritium limit at 100 Bq/L, while the WHO sets it at 10,000 Bq/L.
When it comes to diluting tritium, some environmentalists argue that it is like "diluting whiskey in coke": the presence of coke does not mean there is less alcohol. Similarly, the quantity of tritium in the ocean remains the same; it is simply distributed in a greater quantity of water.
Within the scientific community, the validity of the safety of Japan’s planned water release is thus widely debated. The Woods Hole Oceanographic Institution (WHOI), based in the United States, has regularly voiced concerns about the project’s impact on the environment. The Institute expressed its opposition once again to Japan’s project in December 2022, lamenting the failure to measure concentration rates in all the the reservoirs of the plant.
Yet for Jim Smith, professor of environmental sciences at the University of Portsmouth in the United Kingdom, releasing the wastewater into the ocean "is the best option". The professor, who studies the consequences of radioactive pollutants, argued in an article published on The Conversation that “on the grand scale of the environmental problems we face, the release of wastewater from Fukushima is a relatively minor one.”
An eminently political subject
"This subject is eminently political. It reflects the desire of the Japanese government to make the Fukushima region an example of resilience after a nuclear accident,” said Cécile Asanuma-Brice, a researcher at the CNRS in France and co-director of the MITATE Lab, which studies the consequences of the Fukushima disaster.
“This is the background of the Japanese government's reconstruction policy, which includes dismantling the plant and reopening the area to housing,” Asanuma-Brice explained. “The plant can only be dismantled once they have got rid of these contaminated waters, according to the latest statements by the Minister of Economy and Industry, Yasutoshi Nishimura.”
To carry out the project, the government must also deal with persistent opposition from the local population, especially that of the fishermen's unions. "For [the fishermen's unions], who represent an important part of the country's economy, the question is not so much whether their concerns are justified or not," said Asanuma-Brice. "After the accident, they suffered from a negative image for years, both in the region and internationally. They had just started recovering and regaining a dynamic economic activity. With the project to release the contaminated water, they fear their image will be damaged again and their products shunned by consumers."
Over the years, several alternative solutions have been examined with varying degrees of attention by the authorities. "One of them seems to have gained approval from the local population – that of building new reservoirs or even installing them underground and continuing to store contaminated water until it loses radioactivity in the coming years," said Asanuma-Brice. The idea was rapidly dismissed by the government, which deemed it too expensive.
In addition to the local opposition, the Japanese government will also have to deal with mistrust from other Pacific countries, particularly from China. Following the green light granted by the IAEA in early July, Beijing announced a forthcoming ban on the import of food products from certain Japanese prefectures, including Fukushima, for "security reasons".
This article has been translated from the original in French.
