Tokyo: 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, France 24 reported.

Twelve years after the triple catastrophe, earthquake, tsunami, and 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, France 24 reported.

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.

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, France 24 reported.

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, France 24 reported.

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.

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 an 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), France 24 reported.

"This time, part of the stored water was poured directly onto the reactors in order to cool them,” Gariel added.

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).

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.

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.

To carry out the project, the government must also deal with persistent opposition from the local population, especially that of the fishermen's unions, France 24 reported.

Over the years, several alternative solutions have been examined with varying degrees of attention by the authorities.