Tokyo Electric Power Company has admitted that much of the water stored at its Fukushima Daiichi nuclear plant had not been treated completely enough for release into the environment.
How to dispose of an ever-increasing amount of radioactive water at the plant is a big issue. The contaminated water is generated daily in the process of cooling the damaged reactors.
Before being stored in tanks at the plant, the water undergoes treatment that is supposed to get rid of all radioactive substances but tritium. Tritium is difficult to remove.
One of the disposal ideas is to release the water still containing tritium into the sea.
But many at a public hearing in August opposed to the plan. Some people pointed that the water in question also contains other radioactive elements.
At a meeting of experts in Tokyo on Monday, the utility officials reported that as of August, there was 890,000 tons of such water at the plant.
They said they suspect that more than 80 percent of the water contained not only tritium but also other radioactive substances, such as iodine and strontium, and that their levels exceeded the limits for release into the environment.
A senior Tokyo Electric official apologized, saying his company was too focused on the issue of tritium and failed to provide a full explanation.