Japan mulls air, sea release of water from Fukushima nuclear plant

TOKYO — The Japanese government released a draft report on how to dispose of treated water at the Fukushima No. 1 nuclear power plant on Monday.

The draft includes two methods, narrowed down from five that had been under consideration.

An expert panel, chaired by Ichiro Yamamoto, professor emeritus at Nagoya University, has been calling for the government to decide how and when to dispose of treated water — contaminated water that has undergone purification — at Tokyo Electric Power Company Holdings Inc.’s Fukushima plant.

Releasing the water into the sea after diluting it, releasing it through evaporation and a combination of both options were discussed at Monday’s meeting.

The operation to cool down the melted nuclear fuel in the reactors generates contaminated water, which is then processed with purification equipment that removes radioactive contaminants apart from tritium.

About 1.1 million tons of treated water is being stored in nearly 1,000 tanks at the site. Contaminated water is increasing by about 170 tons a day.

Since autumn 2016, the panel has been studying possible methods for releasing treated water.

Among the five disposal methods studied, the two methods that have delivered proven results and a combination of both have been included in the draft report.

Of the two methods, releasing treated water into the sea after diluting it to a level within the national safety standard is widely conducted at nuclear power plants in Japan.

Under the other method, treated water is evaporated at high temperatures and released via an exhaust stack into the atmosphere, while ensuring radioactive levels are within national air safety standards. A similar method was used after the Three Mile Island nuclear accident in the United States.

Of the five methods, the remaining three ideas, including one in which treated water is buried underground after being hardened with cement, have never been done before, therefore it was concluded they would be difficult in terms of technology and time, the government said.

Regarding the timing and duration of the release, the report states, “The government should make decisions in a responsible way.”

The duration of the release will change depending on when it starts and how much treated water is to be disposed of annually, but it is expected to take at least about 10 years.

“It is necessary to make sure to finish the release of treated water by the time the decommissioning is completed,” according to the draft.

To mitigate against the possible spread of misinformation in affected communities, it also referred to an option of “storing treated water if necessary” and “reducing the impact caused by releasing the water.”

The panel urged the government to listen carefully to the opinions of a wide range of people, including local residents.