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ISSN 2753-7757 (Online)

Japan begins release of Fukushima waste water to the sea


Workers at the Fukushima nuclear plan sampling the treated and diluted waste water Photo: Tepco/IAEA Image Bank
IAEA experts at the Fukushima nuclear plant sampled the treated and diluted waste water to confirm that the tritium concentration was below the operational limit prior to release to the Pacific Ocean

Photo: Tepco/IAEA Image Bank

Tokyo Electric Power Company (Tepco) began releasing treated waste water stored at the Fukushima Daiichi nuclear power plant into the Pacific Ocean on 24 August.

Over a million tonnes of treated waste water, which was used to cool Fukushima’s nuclear reactors, has been stored at the site since it was severely damaged and closed down after a tsunami hit the facility in 2011. Japan’s plan for the release of waste water to the sea caused an outcry from environmental organisations and local communities, including the fishing and seafood industries, when announced and was opposed by neighbouring China, South Korea, North Korea and Taiwan. However, a safety review conducted by the UN nuclear watchdog, the International Atomic Energy Agency (IAEA), concluded that the plan was ‘consistent with IAEA safety standards’ and would have a ‘negligible radiological impact to people and the environment’.


The waste water has been stored in more than 1,000 tanks at Fukushima, but the site was expected to reach full storage capacity by the end of this year/early 2024. It is to be released to the Pacific Ocean over the next 30 years, closely monitored by the IAEA. According to Tepco, prior to its release, the waste water is treated by an advanced liquid processing system (ALPS) that removes most of the radioactive contamination, with the exception of tritium.


On 24 August, the company initially transferred a very small amount of ALPS-treated water – about 1 m3 – to the dilution facility, which was then diluted with about 1,200 m3 of seawater and allowed to flow into the discharge vertical shaft (upstream water tank). The water stored in the discharge vertical shaft was then sampled.


Analysis by Tepco and the Japan Atomic Energy Agency, confirmed by independent IAEA analysis, showed that the level of tritium in the treated water was below the operational limit of 1,500 becquerels per litre.


Tepco then moved to the second stage of the water release plan – continuous discharge into the sea. At the same time, the company began uploading real-time data regarding the discharge of the ALPS-treated water, including water flow rates, radiation monitoring data and the concentration of tritium after dilution, to its website and for IAEA monitoring.


The IAEA is also expected to organise periodic review missions to observe activities on-site Fukushima and to request updates and additional data from Japanese authorities to ensure discharge activities remain ‘consistent with relevant international safety standards’.