IAEA Reports Fourth Interlaboratory Comparison of ALPS Treated Water Radionuclide Analysis
Overview
As part of its safety review of ALPS treated water, the IAEA released results of the fourth interlaboratory comparison for samples collected in July 2025. The report assessed TEPCO’s analytical results, sampling procedures, and analytical methods as appropriate, and concluded that it has the capability to conduct reliable, high-quality monitoring.
Key points
- The IAEA concluded that TEPCO has the capability to conduct reliable, high-quality monitoring of ALPS treated water.
- The samples for the fourth interlaboratory comparison were collected in July 2025 in the presence of the IAEA.
- The reported detection limits were below 1% of the applicable regulatory standards for every radionuclide included in the source term.
Overview
On October 5 (Monday, Vienna local time), the International Atomic Energy Agency (IAEA) released a report on the “Fourth Interlaboratory Comparison for Radionuclide Analysis of ALPS Treated Water.” It follows the third report, published in March 2025.
The report covers results of monitoring verification activities concerning sampling, independent analysis, and data corroboration as part of the safety review of the handling of ALPS treated water. The full review consists of three parts: assessment of protection and safety, regulatory activities and processes, and these verification activities.
Impact
The Japanese government says it will continue measures in accordance with international safety standards through the IAEA review and make every effort to ensure the safety of ocean discharge. It also says it will work with the IAEA to provide the international community with highly transparent information and promote understanding in Japan and abroad.
Details
In the comparison, results from the IAEA laboratory and laboratories in third countries selected by the IAEA were compared for samples collected in July 2025 in the presence of the IAEA from a measurement and confirmation tank. The tank is described as equipment that receives, circulates, and stirs ALPS treated water so that representative samples can be collected for analysis before dilution and discharge.
Among the main findings, TEPCO reported accurate results demonstrating a high level of capability, and its sampling procedures followed appropriate methodological standards for obtaining representative samples. The radionuclide analysis methods used were also deemed appropriate and fit for purpose.
The IAEA said these results confirm TEPCO’s source monitoring capabilities. Based on its observations, it concluded that TEPCO is building a sustainable and robust analytical system to support the technical needs of the Fukushima Daiichi Nuclear Power Station during discharge. Here, “source term” refers to the types and quantities of radioactive materials that may be discharged; in this report, it means information on radionuclides in the discharge water as assumed by TEPCO.