The discharge of ALPS (Advanced Liquid Processing System)-treated water from Japan’s Fukushima Daiichi Nuclear Power Station (FDNPS) is progressing in line with relevant international safety standards, the International Atomic Energy Agency (IAEA) Task Force confirmed this week following its latest five-day mission to Japan, conducted from 15 to 19 December. The mission included on-site inspections of the facilities used for the discharge at the FDNPS.
The IAEA Comprehensive Report on the Safety Review of the ALPS-Treated Water at the Fukushima Daiichi Nuclear Power Station, published in July 2023, concluded that Japan’s approach to discharging the treated water is consistent with international safety standards and that the planned discharge would have a negligible radiological impact on people and the environment.
This mission marks the tenth for the Task Force since the beginning of the IAEA’s multiyear safety review in 2021. The Task Force includes IAEA staff and 11 international experts from Argentina, Australia, Canada, China, France, the Marshall Islands, the Republic of Korea, the Russian Federation, the United Kingdom, the United States and Viet Nam.
“Japan has demonstrated continued effort and commitment to ensuring that the discharge of ALPS-treated water is implemented in line with relevant international safety standards,” said Gustavo Caruso, Chair of the Task Force. “The Task Force noted Japan’s ongoing work to carry out the discharge in accordance with these standards and underscored that the IAEA will continue its independent safety review throughout the process to provide transparency and compliance.”
During this week’s mission, the Task Force focused on activities conducted since the start of the discharge and followed up on technical topics important for safety. In Tokyo, the Task Force met with officials from the Ministry of Foreign Affairs, the Nuclear Regulation Authority, the Ministry of Economy, Trade and Industry, as well as representatives from Tokyo Electric Power Company Holdings (TEPCO), the operator of the FDNPS.
The Task Force also conducted its fifth visit to the ALPS-treated water discharge facilities at the FDNPS since the start of the discharge in August 2023. Through direct observations of facilities and equipment, including a visit to the TEPCO Chemical Analysis Building, the Task Force had the opportunity to observe the laboratory activities carried out by TEPCO related to tritium measurements on ALPS-treated water samples. The Task Force also visited the IAEA on-site laboratory, where the Agency conducts independent monitoring and corroboration of the radioactive concentration.
The Task Force observed the status of the tanks dismantling activities after discharge, which had been visited during the previous mission, and noted that TEPCO has continued to make progress in the decommissioning of these tanks that contained ALPS-treated water. The Task Force also noted that the equipment and facilities are installed and operated in accordance with Japan’s Implementation Plan and relevant international safety standards.
The IAEA’s interlaboratory comparisons – carried out since before the discharges – continue to provide a comprehensive verification of the accuracy and reliability of the monitoring data reported by TEPCO and the Government of Japan. Additionally, the IAEA’s onsite sampling and analysis – conducted at FDNPS since July 2023 – has confirmed that the tritium concentration in the first 17 batches of diluted ALPS treated water remains consistent with international safety standards, far below Japan’s operational limits. Radiation monitors and flow rate detectors at the site also feed live data to the IAEA’s dedicated real-time monitoring page.
Further, the IAEA conducts additional measures, which focus on expanding international participation and transparency, allowing hands-on independent measurements of the concentration level of the ALPS treated water. The latest mission carried out under the additional measures took place in December 2025.
As the main conclusion, the Task Force did not identify any inconsistencies with the requirements of relevant international safety standards, reaffirming the conclusions of the Task Force’s safety review as outlined in the Comprehensive Report of 4 July 2023. Detailed outcomes from the Task Force’s review mission this week will be summarized in a report to be made publicly available next year.
The reports on the first four review missions held by the Task Force since the start of the water discharge are available online.
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