International Atomic Energy Agency (IAEA) experts have confirmed that the tritium concentration in the 11th batch of diluted ALPS treated water, which the Tokyo Electric Power Company (Tepco) began discharging on 12 March, is far below Japan’s operational limit.
Contaminated water, used to cool the melted reactor cores in the aftermath of the 2011 nuclear disaster at Fukushima, is stored in around 1,000 huge tanks at the plant containing more than 1.3m tonnes and total storage capacity has been reached. The contaminated cooling water and groundwater is treated by the Advanced Liquid Processing System (ALPS), which removes most of the radioactive contamination, with the exception of tritium.
The treated water is then stored in tanks before being diluted with seawater to one-fortieth of the concentration permitted under Japanese safety standards before being released one kilometre off the power plant. As a result, tritium levels fall below national regulations. The water is being discharged in batches over a period of approximately 30 years. The first discharge began in August 2023.
As for the previous ten batches, IAEA experts stationed at the Agency’s office at the site of the Fukushima NPP conducted an independent on-site analysis of samples from the treated water. The IAEA confirmed that the tritium concentration in the diluted water is far below the operational limit of 1500 becquerels per litre and is in line with international safety standards. The IAEA confirmed that the tritium concentrations in the previous ten batches, totalling approximately 78.200 cubic meters of water, were also far below operational limits.
In a comprehensive report issued on 4 July 2023 before the discharge began, the IAEA’s safety review found that Japan’s plan for handling the treated water was consistent with international safety standards and that the release as planned would have a negligible radiological impact to people and the environment.
