South Korea has sent a letter to the International Atomic Energy Agency to convey concerns about a possible Japanese plan to release treated radioactive water from the damaged Fukushima Daiichi nuclear plant into the sea.
South Korea's science and technology ministry explained the letter at a news conference on Thursday.
This followed a briefing on the issue given by Japan's government on the previous day for foreign embassy officials, including those from South Korea.
The wastewater contains tritium, with most other radioactive substances filtered out. The water volume has been increasing by about 170 tons a day, and tanks for storing it may become full in summer of 2022.
Japanese officials at the briefing explained several measures being discussed by an expert panel as possible ways to deal with the problem. They include releasing the water into the sea after diluting it, and adding storage tanks.
An official of South Korea's science ministry said on Thursday said that the letter expresses the country's serious concerns about the environment impact of such a release. The official also said South Korea asked the international nuclear watchdog to play a more active role on the issue.
The official added that the country will raise the issue at a general meeting of the IAEA in Vienna that starts on September 16.