Tokyo Electric Power Company Holdings Inc.’s initial ocean discharge of 7,800 tons of treated water from the Fukushima No. 1 nuclear power plant was completed Monday.
Tests carried out in the surrounding waters have detected no abnormalities, and the water-release equipment has been functioning smoothly. The second discharge will begin early October after the results of the first release have been scrutinized, TEPCO said.
TEPCO began releasing the treated water on Aug. 24. On Monday morning, fresh water was used to flush the pipes connecting storage tanks and the discharge facility.
Following the start of the release, the government and TEPCO collected seawater and fish samples from the surrounding areas to check concentration levels of tritium, among other substances. Almost all the results were below the minimum detectable limit.
On one occasion, water sampled near the discharge outlet on Aug. 31 detected tritium at a level of 10 becquerels per liter — far below the national drinking water standard of 60,000 becquerels per liter and the World Health Organization’s drinking water standard of 10,000 becquerels — meaning there is no impact on the environment or health.
The treated water is aqua that has been purified using the Advanced Liquid Processing System by removing multiple radionuclides — except tritium — from contaminated water that was used to cool molten nuclear fuel from the 2011 meltdown.
According to TEPCO, the treated water is diluted with large amounts of seawater before being released into the sea via an undersea tunnel about 1 kilometer offshore from the plant. By the end of March, about 31,200 tons — or about 2% of the water being held in the tanks — is planned to be discharged over four separate release periods.