In just three years the Fukushima Dai-ichi site will have no more room to make the specialised tanks that are used store water that has been used to cool the melted reactors, or has seeped through the site from the surrounding hills. There’s currently over 1.15 million tons of this radioactive water being stored at the facility in 960 tanks and it’s continuing to accumulate at a rate of about 150 tons a day, meaning the tanks could reach full capacity by the summer of 2022.

TEPCO gas put forward a number of ideas to deal with this problem, including the evaporation of the water, injecting it deep underground, or the construction of more long-term storage tanks.

They have also floated the idea of gradually pumping the treated water into the Pacific Ocean. This is the option favored by the International Atomic Energy Agency and Japan’s Nuclear Regulation Authority, however, this is a hugely unpopular choice among local residents and fishermen.

Tepco installed equipment to pump out and decontaminate the water. But the treated water still contains tritium, a radioactive hydrogen isotope that also occurs in minute amounts in nature.

Tritium is the mildly radioactive isotope of hydrogen that has two neutrons and one proton, with radioactivity so low that no environmental or human problems have ever come from it, even though it is a common radioactive element in the environment. Tritium is formed naturally by atmospheric processes as well as in nuclear weapons testing and in nuclear power plants.

But with the 2020 Summer Olympics in Tokyo approaching, the government is worried about a potential blow to its international reputation by releasing the water into the sea. It appears to be dragging its feet on a decision.