An International Atomic Energy Agency safety review has concluded that Japan’s plans to release treated water stored at the Fukushima Daiichi nuclear power station (FDNPS) into the sea are consistent with IAEA safety standards. In a report formally presented by IAEA director general Rafael Mariano Grossi to Japanese prime minister Fumio Kishida during his recent visit to Tokyo, the IAEA also said discharges of the treated water would have a negligible radiological impact on people or the environment.

The report is the result of investigations over almost two years by an IAEA Task Force comprising top specialists from within the Agency advised by internationally recognised nuclear safety experts. The Task Force is chaired by a senior IAEA official and includes experts from the IAEA Secretariat alongside independent experts with extensive experience from a wide range of technical specialties from Argentina, Australia, Canada, China, France, the Marshall Islands, South Korea, Russia, the UK, the USA and Viet Nam. They reviewed Japan’s plans against IAEA Safety Standards which serve as a global reference for protecting people and the environment.

Japan’s Nuclear Regulation Authority, NRA, approved the plan to release treated water stored at the Fukushima Daiichi NPP in July 2022. The water, used to cool the melted reactor cores in the aftermath of the 2011 disaster, is stored in around 1000 tanks at the plant containing more than 1.3 m tonnes. Total storage capacity has been reached and NRA has deemed it safe to release the water following treatment, although it will still contain traces of tritium.

The contaminated cooling water and groundwater is treated by the Advanced Liquid Processing System (ALPS), which removes most of the radioactive contamination, with the exception of tritium. The government therefore plans to dilute the treated water so that tritium levels fall below national regulations before releasing it. Japan initially announced plans to discharge treated water into the sea over a period of about 30 years in April 2021, asking the IAEA to review these plans.

The IAEA’s review addressed all key safety elements of the water discharge plan in three major components: assessment of protection and safety; regulatory activities and processes; and independent sampling, data corroboration, and analysis.

The IAEA‘s safety review will continue during the discharge phase. The Agency will also have a continuous on-site presence and provide live online monitoring on its website from the discharge facility. “This will ensure the relevant international safety standards continue to be applied throughout the decades-long process laid out by the government of Japan and Tepco,” said DG Grossi.

Image: Tanks of treated water at the Fukushima Daiichi site (courtesy of IAEA)