A South Korean delegation of experts will continue their analysis back home on Japan's plan to discharge treated radioactive water into the sea from the disaster-hit Fukushima nuclear power plant, the group said Thursday after inspecting it.

The delegation of 21 experts from agencies and affiliated organizations of the South Korean government with expertise in radiation and nuclear reactors, among other fields, held a meeting with Japanese officials to summarize their observations following the 2-day inspection, telling the Japanese side they still needed to confirm several things before releasing their conclusion on the plan's safety.

They requested additional materials, such as protocols for a power outage and a long-term management plan for an advanced liquid processing system capable of removing radionuclides other than tritium in water.

Yoo Guk Hee, chairman of South Korea's Nuclear Safety and Security Commission, speaks to reporters in Tokyo on May 25, 2023. (Kyodo)

Officials of the Foreign Ministry, industry ministry, Nuclear Regulation Authority and the plant operator, Tokyo Electric Power Company Holdings Inc., represented Japan in the meeting.

At the Fukushima Daiichi power complex, which suffered core meltdowns triggered by a massive earthquake and tsunami in 2011, the delegation observed the ALPS water treatment system and confirmed the location and function of emergency isolation valves, among other equipment, on Tuesday and Wednesday.

The valves are installed to immediately halt the discharge of ALPS-treated water into the sea in the event of an abnormality, a mandatory function of the discharge facilities, according to Tokyo Electric.

"We confirmed things such as how to control facilities and those valves function when the power is out during an emergency," delegation chief Yoo Guk Hee, chairman of the Nuclear Safety and Security Commission, told reporters after the meeting.

"We provided thorough explanations and showed them as many facilities as possible," an official of the Economy, Trade and Industry Ministry told reporters.

Separately, the International Atomic Energy Agency is reviewing the process of the water release, which is planned to begin in the summer and continue for decades, as well as its possible

The experts have not collected any sample of ALPS-treated water during the inspection, but a South Korean institute already received one from the IAEA, as the agency has provided samples to selected third-party laboratories in France, South Korea, Switzerland and the United States that have been involved in interlaboratory comparison for ALPS treated water.

Yoo suggested that the group will release the outcome of its inspection after the IAEA issues a comprehensive report about its findings, which is expected by the end of June.

Japan plans to eject the treated water after diluting it with seawater to below one-40th of the concentration permitted under Japanese safety standards. The water will be released 1 kilometer off the plant via an underwater pipeline.

Japanese Prime Minister Fumio Kishida and South Korean President Yoon Suk Yeol agreed on Seoul's dispatch of the delegation at their summit earlier in May, amid worries among the South Korean public about how the discharged water could affect health and the ocean environment.

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