Press Releases

Publication of the IAEA Report on the Review of Handling ALPS Treated Water at TEPCO’s Fukushima Daiichi Nuclear Power Station

September 16, 2025
Japanese

On September 12, the IAEA published a report on its fourth review mission conducted in May 2025 after the start of the discharge of the ALPS treated water from TEPCO’s Fukushima Daiichi Nuclear Power Station (FDNPS) into the sea.

  1. This IAEA review is based on the Terms of Reference (TOR) on reviews of safety aspects of handling ALPS treated water signed in July 2021 with the IAEA.
  2. This IAEA report includes the following major conclusions;
    1. The Task Force did not identify anything that is inconsistent with the requirements in the relevant international safety standards. Therefore, the IAEA can reaffirm the fundamental conclusions of its safety review as outlined in the Comprehensive Report.
    2. The Task Force noted that the monitoring programmes carried out for the ALPS treated water are consistent with the relevant international safety standards and guidance. The programmes are well described and implemented, and results are consistent with the conclusions of the Radiological Environmental Impact Assessment (REIA) which states the discharges of ALPS treated water pose negligible risk to the public and environment.
  3. The independent review by the IAEA, an international organization with authority in the field of nuclear energy, is extremely important in ensuring reliability and transparency regarding the safety of the discharge of the ALPS treated water into the sea and fostering better understanding both domestically and internationally. The Government of Japan will continue to work firmly to gain further understanding of the ALPS treated water both domestically and internationally.

(Reference1) ALPS treated water

ALPS treated water is water which is processed by devices such as ALPS (Advanced Liquid Processing System) to ensure that the concentration of the radioactive materials other than tritium surely meets the regulatory standards for safety. In addition, ALPS treated water is sufficiently diluted with seawater before the discharge into the sea so that radioactive materials including tritium are far below the regulatory standards for safety.

(Reference2) Composition of IAEA Task Force

The IAEA Task Force includes 11 international experts, serving in an independent position, from Argentina, Australia, Canada, China, France, the Marshall Islands, Republic of Korea, Russia, the United Kingdom, the United States, and Vietnam.

(Reference3) Related links

  1. The IAEA Press ReleaseOpen a New Window
  2. Report on the Mission to Japan conducted in May 2025 (PDF) Open a New Window
  3. The 1st report (PDF) Open a New Window
    published on April 29, 2022, describes the details of IAEA’s review mission to METI and TEPCO conducted in February 2022, related to eight different technical areas, including the characterization of discharge and source term, the safety-related aspects of system and processes for controlling discharges, and the radiological environmental impact assessment.
  4. The 2nd report (PDF) Open a New Window
    published on June 16, 2022, describes the details of IAEA’s review mission to the Nuclear Regulation Authority conducted in March 2022, related to five technical topics, including the responsibilities and functions of the government, major principles and safety objectives, and authorization process.
  5. The 3rd report (PDF) Open a New Window
    published on December 29, 2022, describes the IAEA’s planned activities for the analysis and data corroboration of source monitoring of the ALPS treated water, environmental monitoring, and occupational radiation protection for workers at the FDNPS.
  6. The 4th report (PDF) Open a New Window
    published on April 5, 2023, describes the details of IAEA’s review mission to METI and TEPCO conducted in November 2022, related to eight different technical areas, including the characterization of discharge and source term, the safety-related aspects of system and processes for controlling discharges, and the radiological environmental impact assessment.
  7. The 5th report (PDF) Open a New Window
    published on May 4, 2023, describes the details of IAEA’s review mission to the Nuclear Regulation Authority conducted in January 2023, related to the five technical topics, including the responsibilities and function of the government, major principles and safety objectives, and authorization process.
  8. The report “IAEA Comprehensive Report on the Safety Review of the ALPS Treated Water at the Fukushima Daiichi Nuclear Power Station” (PDF) Open a New Window
    published on July 4, 2023, summarizes a series of reviews which were conducted by the IAEA before the start of the discharge of the ALPS treated water.
  9. The report” First Review Mission to Japan after the Start of ALPS Treated Water Discharge (October 2023)” (PDF) Open a New Window
    published on January 30, 2024, summarizes the results of the first review which was conducted by the IAEA after the start of the discharge of the ALPS treated water.
  10. The report” Report on the Mission to Japan conducted in April 2024” (PDF) Open a New Window
    published on July 18, 2024, summarizes the results of the second review which was conducted by the IAEA after the start of the discharge of the ALPS treated water.
  11. The report “Report on the Mission to Japan conducted in December 2024” (PDF) Open a New Window
    published on March 24, 2025, summarizes the results of the third review which was conducted by the IAEA after the start of the discharge of the ALPS treated water.

Related Links

Back to Press Releases