This Monday, the International Atomic Energy Agency (IAEA) begins a five-day monitoring mission of the project to discharge radioactive water from the Fukushima nuclear power plant. For Japan, “taking a decision was urgent”, underlines Jean-Christophe Gariel, Deputy Director General at the Institute for Radiation Protection and Nuclear Safety (IRSN). More than ten years after the disaster, 1.2 million cubic meters of contaminated water, resulting from cooling, groundwater and rain, is collected on the site of the nuclear power plant. However, the maximum storage capacity is “1.3 million cubic meters”, specifies our expert in charge of the environment and health at IRSN.
Despite the urgency, the discharge of these contaminated waters continues to cause concern and reluctance. That’s why Tepco, the operator of the damaged nuclear power plant, and the Japanese government hope that the IAEA’s oversight of the process will boost confidence. This five-day mission – which is due to end on Friday with a press conference – will offer them a form of “guarantee” by checking the processes for controlling the tritium content, the checkpoints in the environment or the methods envisaged. for rejection.
Between radionuclides and tritium
After the tsunami that devastated the Fukushima nuclear power plant in 2011, Tokyo implemented a myriad of decontamination and site management procedures. The molten reactor cores are still cooled every day by about 200 cubic meters of water. A water that fills up with radioactive elements during its mission. So, for years, Tokyo has been filtering this water which has been contaminated after coming into contact with the reactors or molten elements of the latter. “A device enables them to filter all the radionuclides contained in the water, with the exception of tritium”, explains Jean-Christophe Gariel.
Tritium is an isotope of hydrogen, an atom whose composition is close to hydrogen. In water, it therefore easily replaces hydrogen and scientists do not know how to isolate it. “Filtering water always gives water”, image the DGA of IRSN. If it is an integral part of the radioactive elements, it “is not the most dangerous”.
Especially since its radioactivity decreases by half every twelve years, a rather rapid ratio compared to other radioactive elements. Even better, as the International Atomic Energy Agency has repeatedly said, the plan to dump this filtered water into the ocean is similar to disposing of wastewater from an active nuclear power plant. “The planned releases will be equivalent to those that would have occurred if the plant was still in operation,” confirms Jean-Christophe Gariel.
No health or environmental concerns
Moreover, in order to prevent this tritium from coming back to settle on the coasts and encouraging a strong dilution, the Japanese government has planned the construction of an underwater tunnel one kilometer long. The contaminated water will thus gradually be diluted in the Pacific Ocean from March 2023 to quickly reach the same levels of effectiveness as homeopathy. This spill, which will take place over years, presents “no health problem, neither for humans nor for the environment”, repeats the IRSN member.
Other solutions had been considered, such as burying the contaminated water in concrete blocks, evaporating it or injecting it into basements. In each of the scenarios, the same quantity of tritium would have been released into the environment, but dilution in water was preferred because it is already used everywhere in the world and the “fallouts are easier to understand”.
The radioactive pokemon
In the hope of calming people’s minds, the Japanese government has developed treasures of imagination and set up educational, reassuring and… sometimes awkward communication. In 2021, when the executive announced its intention to discharge the waters of Fukushima into the ocean, it coupled the announcement with a communication campaign in which tritium was represented by a Pokémon-like mascot. The “kawaï” mascot had to be withdrawn after only a few days of existence and a wave of indignation on social networks.
Concerns remain strong and some organizations, like Greenpeace, oppose this rejection. Japanese fishermen also fear that the contaminated water will ruin years of work to restore confidence in their products, while also internationally the decision has provoked many reactions, in particular from the direct neighbors of the Japanese archipelago. .
Because if, concretely, the rejections of the Japanese government are the same as for any plant in operation, conceptually, they remain the consequence of a nuclear accident.