TOKYO - Japan started discharging treated radioactive water from the wrecked Fukushima Daiichi nuclear power plant into the sea Thursday, amid persistent concerns among local fishermen and some neighboring countries about the environmental impact.

The disposal of the water, treated and stored in tanks after cooling melted nuclear fuel, is an integral part of the decommissioning of the power plant devastated by a catastrophic earthquake and tsunami in 2011, the government said.

The water discharge, commenced by the plant operator Tokyo Electric Power Company Holdings Inc. around 1 p.m., is expected to last around 30 years or more.

The water has been treated through an advanced liquid processing system capable of removing most radionuclides except tritium.

The start of the water discharge prompted an immediate response from local fisheries communities and neighboring countries and regions that hold safety concerns.

The crippled Fukushima Daiichi nuclear power plant is pictured from Namie, Fukushima Prefecture, on the morning of Aug. 24, 2023. (Kyodo) 

China suspended imports of all seafood products from Japan, calling the water release "an extremely selfish and irresponsible act." Hong Kong began imposing restrictions on seafood imports from Tokyo and nine Japanese prefectures including Fukushima.

"We have requested the withdrawal (of China's ban) through diplomatic channels. We strongly encourage discussion among experts based on scientific grounds," Japanese Prime Minister Fumio Kishida told reporters at his office.

TEPCO President Tomoaki Kobayakawa assured that the plant operator is committed to providing appropriate compensation if companies doing business in Japan experience export losses due to import limitations enforced by foreign governments over the water discharge.

Economy, Trade and Industry Minister Yasutoshi Nishimura, who oversees the utility industry, pledged to ensure transparency in presenting environmental monitoring data when he met reporters after the start of the discharge.

The first batch of such data will be publicly released on Friday at the earliest, according to TEPCO.

TEPCO dispatched a ship to take samples of seawater at 10 spots in waters off the power plant to monitor the level of tritium.



The discharge came as tanks installed at the Fukushima complex, currently containing about 1.34 million tons of treated water, were expected to reach their capacity limit as early as 2024 unless TEPCO initiated the release of the water.

Shinsuke Yamanaka, chairman of Japan's Nuclear Regulation Authority, said at a press conference on Wednesday that the discharge is a "significant step forward" toward the decommissioning of the Fukushima Daiichi power plant.

The water is diluted with seawater to one-40th of the concentration permitted under Japanese safety standards before being released via an underwater tunnel 1 kilometer from the seaside plant.

A total of 31,200 tons of treated water containing 5 trillion becquerels of tritium, about one-fourth of the annual maximum limit allowed for release into the environment, is slated for dumping in the sea in four runs through next March, TEPCO has said.

TEPCO will release the first batch of the water, totaling 7,800 tons, into the sea in a period of about 17 days.

Shortly before the start of the water release, TEPCO announced it had measured the maximum concentration of tritium in the diluted water at 63 becquerels per liter, far below the limit of 1,500 becquerels.

Measurements by the Japan Atomic Energy Agency and the International Atomic Energy Agency showed similar results, according to the agencies.

The IAEA set up a web page to provide live data on the water disposal, such as radiation monitoring data from the water transfer line, the flow rate in the water line and the concentration of tritium in the diluted water prior to the sea disposal.

In July, the IAEA concluded that the discharge plan aligned with global safety standards and would have a "negligible" impact on people and the environment, prompting the Japanese government to proceed with the water disposal plan set forth in 2021.

The South Korean government has said it respects the outcome of the IAEA's review based on its own analysis of Japan's plan, but it will not endorse or support the water discharge in consideration of persisting concerns among the public.

The IAEA said it will regularly inform South Korea about the discharge of treated water to address public concerns in the country.

Seoul said after the start of the discharge that it is not overly concerned so long as the water release goes as planned, calling on Japan to disclose information transparently and responsibly.

Besides Japan's fishing community, an organization of fishermen in the Philippines has also voiced concern over the water disposal.

Japan's Fisheries Agency will monitor concentration levels of radioactive materials in fish caught within a 10-km radius of the power plant every day for the time being.

The first results are expected to be released on the agency's website starting Saturday, according to the agency.

The Environment Ministry will also analyze the concentration level of tritium in seawater off parts of the eastern and northeastern coasts.

Nuclear power plants worldwide routinely release treated water containing low-level concentrations of tritium and other radionuclides into the environment as part of normal operations, according to the IAEA.

Fishing boats are moored at a fishing port in Namie, Fukushima Prefecture, on Aug. 24, 2023, with the crippled Fukushima Daiichi nuclear power plant seen in the background. (Kyodo) 

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