The International Atomic Energy Agency (IAEA) says it has been informed by Japan’s Tokyo Electric Power Company (Tepco), operator of the Fukushima Daiichi NPP, that localised corrosion and flaking of paint had been discovered on three tanks used to store treated contaminated water at the site.
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 so that tritium levels fall below national regulations before it is released through an undersea tunnel into the Pacific Ocean.
During a routine walkdown of the tanks that had been emptied after transferring the water Tepco staff noted the corrosion and flaking on three tanks. These three tanks are currently empty, and an assessment determined that the corrosion bore no impact on the structural integrity of the tanks, and no water had leaked. The corrosion does not pose any safety risk, and there is no environmental impact. The event is not related to the discharge of the ALPS treated water. The damaged section will be repaired prior to using the tanks again to store ALPS treated water, Tepco said. Japan’s Nuclear Regulatory Authority has been informed, and inspectors at the plant are conducting an on-site investigation.
Image: An IAEA task force inspects tanks of treated water at the Fukushima Daiichi nuclear power plant (courtesy of Tepco)
