A team of scientists from the International Atomic Energy Agency (IAEA) will return to Japan next week to conduct marine sampling near the Fukushima Daiichi Nuclear Power Station (FDNPS). This mission is part of the Agency's extensive monitoring and assessment activities that support its ongoing safety review of the ALPS treated water discharges.
The IAEA conducts interlaboratory comparisons (ILCs) based on marine environment samples to verify the radiological data used by Japan in planning and implementing the water discharges. The ILCs also facilitate assessments of the application of relevant international safety standards in establishing and implementing monitoring programmes to accurately evaluate public exposure by Tokyo Electric Power Company (TEPCO) - operator of the plant - and the Government of Japan.
From 7 to 18 October, the IAEA team will observe the collection of seawater, marine sediment, fish and seaweed samples from coastal waters in the vicinity of the FDNPS. The mission will also include sampling at a local fish market and monitoring the preparation of samples for delivery to participating laboratories.
International experts from the Third Institute of Oceanography, China, the Korea Institute of Nuclear Safety, and the Spiez Laboratory, Switzerland-all members of the IAEA's Analytical Laboratories for the Measurement of Environmental Radioactivity (ALMERA) network - will participate in the mission to provide independent corroboration of Japan's environmental monitoring capabilities.
After collection, the samples will be sent to all participating laboratories for analysis for a range of radionuclides. The results of analyses from the IAEA Laboratories in Monaco and Vienna, the ALMERA member laboratories as well as the participating Japanese laboratories, will be submitted to the IAEA for evaluation, with a focus on identifying any statistically significant differences.
The results of the analyses of the samples can also be compared with those from previous ILCs to assess any changes in radionuclide levels in the marine environment since the discharge of ALPS-treated water began in August last year.
The findings will be publicly released to ensure transparency by September 2025.
This mission is part of the IAEA's extensive monitoring and assessment activities for the safety review of ALPS-treated water. In the series of ILCs, the Agency has already published several reports evaluating TEPCO's capabilities for accurately measuring the radionuclides in the treated water stored on site, and another analyzing radionuclides in seawater, sediment, fish, and seaweed samples collected in November 2022.
Additionally, IAEA experts stationed at the Agency's office at FDNPS conduct regular independent on-site analyses of the batches of treated water. In September this year, the Agency confirmed that the tritium level in the ninth batch of ALPS treated water was far below Japan's operational limit. The IAEA has earlier confirmed that the tritium concentrations in the previous eight batches, totalling approximately 64 500 cubic meters of water, were also far below operational limits.
Next week's mission will also provide samples for the Agency's ILC project initiated in 2014 to support the quality assurance of broader marine environmental monitoring by Japanese laboratories. The results for this segment of the work will be released in June 2025.
