A team of experts from the International Atomic Energy Agency has arrived in Japan to inspect the project to release treated water from the damaged Fukushima Daiichi nuclear power plant into the sea.
The IAEA has been asked by the Japanese government to assess the safety of the release. This is the agency's second mission following one in February.
The visiting team is made up of experts from 11 countries, including China, South Korea and the United States, as well as IAEA officials.
The members exchanged views with officials of the industry ministry and the plant's operator, Tokyo Electric Power Company, on Monday morning.
They include the IAEA director and coordinator for nuclear safety and security, Gustavo Caruso.
Caruso said it is the Japanese government's responsibility to ensure the safety of the Fukushima treated water, but the IAEA will also make an objective and scientific assessment.
Water is used to cool molten nuclear fuel at the plant. It mixed with groundwater and rainwater that flows into damaged reactor buildings.
The plant operator is treating the water by filtering out most of the radioactive substances. But treated water still contains radioactive tritium and some other radioactive substances.
The government and Tokyo Electric hope to start releasing treated water around next spring after diluting the tritium levels to below national regulations.
But concerns about its safety have been voiced at home and abroad.
The IAEA mission is to stay in Japan through Friday. The experts will visit the Fukushima plant on Wednesday to inspect the construction of an undersea tunnel to be used for releasing the water about 1 kilometer offshore.
They also plan to confirm the types of radioactive substances other than tritium that are to be removed before the release.
The IAEA plans to issue a report on its inspections at an early date in 2023.