IAEA and International Laboratories Confirm Japanese Monitoring Data for ALPS Treated Water Discharge under Additional Measures

The International Atomic Energy Agency (IAEA) today published three new reports on the analytical results of the Additional Measures, confirming the consistency of independent assessments conducted by laboratories in China, France, the Republic of Korea, the Russian Federation and Switzerland – as well as by the IAEA’s and Japanese laboratories. 

The measurement results are consistent with the conclusions of the IAEA Comprehensive Report, which found that the discharges as planned would have a negligible radiological impact on people and the environment, the reports state.

The Additional Measures was introduced to permit third-party laboratories to independently verify that the discharge of ALPS treated water, which Tokyo Electric Power Company Holdings (TEPCO), operator of the Fukushima Daiichi Nuclear Power Station (FDNPS), began in August 2023 continues to be consistent with international safety standards. The measures focus on expanding international participation and transparency in the IAEA’s sampling and independent analysis. 

Two reports issued today cover two missions conducted in February when IAEA Director General Rafael Mariano Grossi presided over the Additional Measures to collect seawater in the vicinity of FDNPS and when experts selected fish samples and samples of ALPS treated water prior to its dilution with seawater. The third report covers an expert mission in April when experts collected samples of ALPS treated water diluted with seawater prior to the discharge into the sea. These reports follow the Additional Measures report published on 2 June 2025, which covered the IAEA mission to participate in marine sampling near FDNPS in October 2024, bringing the total number of reports to four.

All samples were analysed independently by the participating laboratories – in the case of these four reports, in China, France, the Republic of Korea, the Russian Federation and Switzerland – as well as by the IAEA’s laboratories and Japanese laboratories conducting analysis of marine environment monitoring. All third-party laboratories are members of the IAEA’s Analytical Laboratories for the Measurement of Environmental Radioactivity (ALMERA) network, selected for their high level of expertise and analytical proficiency. These reports – and Additional Measures generally – cover all key steps of the discharge process: ALPS treated water before dilution with seawater, ALPS treated water diluted with seawater, and sampling of seawater and fish close to the discharge outlet. 

Each report includes the results from all laboratories involved and an IAEA evaluation to assess comparability and consistency of data. The reports can be found at the links below: