Discharge of radioactive water of the Fukushima Daiichi Nuclear Power Plant
Radioactive water from a 2011 nuclear accident in Japan / From Wikipedia, the free encyclopedia
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Radioactive water from the Fukushima Daiichi Nuclear Power Plant in Japan began being discharged into the Pacific Ocean on 11 March 2011, following the Fukushima Daiichi nuclear disaster triggered by the Tōhoku earthquake and tsunami. Three of the plant's reactors experienced meltdowns, leaving behind melted fuel debris. Water was introduced to prevent the meltdowns from progressing further. When cooling water, groundwater, and rain came into contact with the melted fuel debris, they became contaminated with radioactive nuclides, such as iodine-131, caesium-134, caesium-137, and strontium-90.[3][4]
Over 500,000 tonnes of untreated wastewater (including 10,000 tonnes released to free up storage space) escaped into the ocean shortly after the accident. In addition, persistent leakage into groundwater was not admitted by the plant operator until 2013. The radioactivity from these sources exceeded legal limits.[5][6]
Since then, contaminated water has been pumped into storage units and gradually treated using the Advanced Liquid Processing System (ALPS) to eliminate most radionuclides,[3][7] except notably tritium with a half-life of 12.32 years.[8][9] In 2021, the Japanese cabinet approved the release of ALPS-treated water containing 1.8 g (0.1 oz) of tritium.[10][11] Because it is still radioactive immediately after treatment, the solution will be diluted by sea water to a lower concentration before being discharged.[12]
A review report by the International Atomic Energy Agency (IAEA) shows that the plan of discharging diluted ALPS-treated water into the sea is consistent with relevant international safety standards. It also emphasizes that the release of the treated water is a national decision by the Government of Japan and its report is neither a recommendation nor an endorsement of the decision.[13]
On 24 August 2023, the power plant started releasing the treated portion of its wastewater into the Pacific Ocean. At the time, its storage units held over a million tonnes of wastewater in total. Because new wastewater is constantly being formed and even treated water must be discharged slowly by diluting it with more sea water, the entire process could take more than 30 years.[14] The decision to release this water into the ocean has faced concerns and criticism from other countries and international organisations.
On 11 September 2023, the IAEA stated that the seawater adjacent to Fukushima Daiichi had no rise in tritium levels since discharges began and values remained below Japan's operational limits.[15][16]