The International Atomic Energy Agency (IAEA) Task Force, which is conducting a safety review of Japan’s discharge of treated water to the sea from the Fukushima Daiichi NPP (FDNPP), has issued its first full report since the discharge began in 2023. The Task Force found the discharge to be consistent with international safety standards and reaffirmed the conclusions from the Agency’s comprehensive safety report issued in July last year.

During its mission from 24 to 27 October 2023, the Task Force reviewed the facilities and equipment installed at FDNPP to discharge the ALPS (Advanced Liquid Processing System) treated water. It also met with plant operator Tokyo Electric Power Company (Tepco), Japan’s Ministry of Economy, Trade & Industry (Meti) and the Nuclear Regulation Authority (NRA).

The IAEA’s comprehensive report – issued before the discharge began – found Japan’s plan for handling the treated water was consistent with international safety standards and that the planned discharge would have a negligible radiological impact to people and the environment. Japan started to discharge the water on 24 August 2023 and has so far completed the release of three batches totalling 23 400 cubic metres of water.

The Task Force, comprising IAEA and independent experts from 11 countries, was appointed by IAEA Director General Rafael Mariano Grossi in 2021 to review the safety of Japan’s plan for the water stored at the Fukushima Daiichi NPS against international safety standards. Based on their assessments made during the October mission, the Task Force concluded the following:

  • A robust regulatory infrastructure is in place in Japan to provide operational safety oversight of the discharge of ALPS treated water, and the Task Force was able to witness first-hand the onsite presence of the NRA and its activities in this regard.
  • Based on its observations, the Task Force confirmed that the equipment and facilities are installed and operated in a manner consistent with Japan’s plan for the release of the water and the relevant international safety standards.
  • The Task Force reiterated the finding from the IAEA’s comprehensive report that optimisation of protection needs to be considered as part of the overall decommissioning of the FDNPP site. However, the Task Force recognised that the discharges are in the early stages and that more time and operational experience are required before progress can be made on this issue.

As part of its ongoing multiyear safety review, the IAEA will continue to conduct Task Force review missions. The Agency also maintains its continuous presence at the IAEA Fukushima Daiichi NPS Office to monitor and assess the ongoing water discharge.

Separately, IAEA also issued two reports as part of its safety review of the water discharge detailing the latest findings of its ongoing corroboration of the measurement data underpinning Japan’s plan for the discharge of the ALPS treated water.

The IAEA is conducting a series of inter-laboratory comparisons (ILCs) to corroborate the source and environmental monitoring conducted by Tepco and other relevant Japanese authorities for the ALPS treated water discharge. Consistent with relevant IAEA international safety standards, Tepco is required to monitor the characteristics and activity of the treated water. It is also required to establish and implement monitoring programmes to accurately evaluate public exposure due to the discharge and to comply with its national regulatory authorisation.

The first report describes an ILC that assessed Tepco’s capabilities for accurate and precise measurements of the radionuclides present in the treated water stored on site. Water samples were taken in October 2022 from two tanks. In the second report, IAEA details an inter-comparison of radionuclides analyses in samples of seawater, sediment, fish and seaweed taken in November 2022 from offshore locations and a fish market close to FDNPP.

This exercise, which was carried out before the start of the water discharge, corroborates monitoring intended to establish a baseline for activity concentrations in the marine environment against which any future impact can be measured.

The ILCs involved laboratories from the IAEA Nuclear Sciences & Applications Department, an external laboratory in the Republic of Korea and laboratories in Japan separately analysing samples. This was followed by a quantitative comparison of the results by IAEA. The results of both ILCs provide confidence in Japan’s capability for undertaking accurate and precise measurements related to the discharge of ALPS treated water. Additional ILCs will be conducted in the future for ALPS treated water, as well as environmental samples, and occupational radiation protection.

Image: Data from Fukushima Daiichi ALPS Treated Water Discharge (courtesy of IAEA)