The IAEA is conducting independent analysis and data corroboration related to the discharge of treated water from the Fukushima Daiichi Nuclear Power Station to validate data reported by Japan. These activities are one component of the three-pronged safety review being conducted by the IAEA Task Force, which was established by Director General Rafael Mariano Grossi in 2021, comprising 11 international experts from around the world, as well as IAEA staff. The other two components are the technical assessment of public safety and protection and the review of regulatory activities and processes, both of which are ongoing and expected to culminate with a comprehensive report in 2023, prior to the discharge of the treated water.
The ongoing analysis of the treated water is intended to corroborate the radiological characterization provided by Tokyo Electric Power Company (TEPCO), the operator of Fukushima Daiichi. TEPCO is responsible for determining that the water is suitable for discharge into the surrounding sea after its treatment to remove 62 radionuclides from the water. Since the 2011 Fukushima Daiichi accident, water that has been used to cool the melted fuel and fuel debris has been treated and stored on site. The IAEA’s corroboration work will continue even after starting the release of the treated water, planned for 2023, as part of Mr Grossi’s commitment to remain involved before, during and after the discharge of treated water.
“Through this safety review, the IAEA is leveraging the robust capabilities of our laboratories to enhance transparency and to provide confidence to the international community,” said Gustavo Caruso, Director at the IAEA and Chair of the Task Force.
IAEA laboratories provide comprehensive analysis
Three of the four IAEA laboratories involved are environmental labs: the Isotope Hydrology Laboratory in Vienna; the Terrestrial Environmental Radiochemistry Laboratory in Seibersdorf, 35 kilometres south of Vienna; and the Radiometrics Laboratory in Monaco. The other laboratory is the Radiation Safety Technical Services Laboratory in Vienna.
From 29 August to 2 September, the Task Force met in Vienna and travelled to Seibersdorf and Monaco to visit all four laboratories. They discussed the analytical techniques to assess the radionuclide content of the samples, the timeline for the work and future analyses for additional samples.
IAEA experts briefed the Task Force on preparations to conduct the analysis of more than 30 different radioisotopes in each water sample with the support of advanced instrumentation. The experts explained the differences in how each radioisotope is measured and how samples are prepared. Joint development work at the laboratories combined with individual separate analysis will ensure best possible results even for challenging analyses of otherwise uncommon radionuclides. “The IAEA laboratories are working together to ensure a comprehensive scientific analysis and to corroborate the data from TEPCO. We are working hard to ensure these initial results can be provided to the international community prior to the start of the water discharge in 2023,” Caruso said.
The Task Force also discussed methods and preparations for the corroboration of the occupational radiation protection capabilities of TEPCO and the Fukushima Daiichi Nuclear Power Station. The proposed technical review and assessment are based on the requirements for assessment of occupational exposure specified in General Safety Guide No. GSG-7.
Earlier this year, the IAEA facilitated two sampling campaigns of treated water from Fukushima Daiichi for analysis by the Agency and third-party laboratories. Additional sampling campaigns from Fukushima Daiichi and the surrounding marine environment are planned over the coming months and years. The IAEA conducts regular performance tests for about 500 laboratories measuring radionuclides in the environment each year, which serve as scientific baselines for assessing the quality and capabilities of participating laboratories.
About the Fukushima Daiichi treated water and IAEA safety review
In April 2021, Japan announced the Basic Policy on handling of the treated water stored at the Fukushima Daiichi site, which is to gradually discharge the treated water into the sea surrounding the plant, subject to domestic regulatory approvals. Water accumulating at the site since the 2011 accident has been treated through a filtration process known as Advanced Liquid Processing System (ALPS) using a series of chemical reactions to remove 62 radionuclides from the water. However, ALPS is not able to remove tritium from the contaminated water (see The Science). The country’s authorities requested assistance from the IAEA to monitor and review plans and activities related to the discharge of the treated water to ensure that these will be implemented in a safe and transparent way. Mr Grossi established the Task Force in 2021 to provide Japan and the international community with an objective and science-based safety review of the discharge activities at the site. Since then, the group of more than 25 experts, including from the region, have met eight times and have completed five site visits to Fukushima Daiichi.
Earlier this year, the IAEA Task Force released its first report on safety of the planned water discharge, and in June, a second report on regulatory aspects was released. A third report is expected to be released later this year and will provide a comprehensive overview of the IAEA’s planned activities to corroborate relevant radiological data under its broader safety review.
Learn more about the Fukushima Daiichi treated water discharge.
What is tritium?
Tritium is a naturally occurring radioactive form of hydrogen that is produced in the atmosphere when cosmic rays collide with air molecules and has the lowest radiological impact of all naturally occurring radionuclides in seawater. Tritium is also a by-product of operating nuclear power plants to produce electricity.
Tritium is an isotope of hydrogen, and water containing tritium has chemical features almost identical to water with ordinary hydrogen. It is technically very difficult to remove tritiated water from water.
Tritium has a radioactive half-life of 12.32 years. This means that for any given amount of tritium, only half will remain after 12.32 years due to radioactive decay. Tritiated water has a relatively short biological half-life in the human body of 7 to 14 days. The biological half-life of a chemical (e.g., a drug) in a living organism is the time it takes for half of that chemical to be depleted or eliminated from the body.