The operator of the crippled Fukushima Daiichi nuclear power plant will begin releasing a fourth round of treated radioactive water into the ocean on Wednesday, the last release for the fiscal year ending in March.
The move comes after the central government and Tokyo Electric Power Company Holdings Inc. confirmed that the latest batch of water met radioactivity levels within standards set by TEPCO on Monday. Despite the opposition of countries like China, the discharge of waste water started in August last year.
As with the previous three rounds, a total of 7,800 tons of processed liquid will flow into the Pacific Ocean over about 17 days.
TEPCO and the federal government's removal of treated water was key to decommissioning the nuclear plant, which suffered a reactor fuel meltdown in 2011 following a devastating earthquake and tsunami disaster. The water release is expected to last for about three decades.
A photo taken from a Kyoto News helicopter on February 11, 2024 shows the Fukushima Daiichi nuclear power plant.(Kyoto)
Massive amounts of contaminated water are generated in the process of cooling the molten fuel. Tanks installed at the site have been watered through a liquid processing system that removes most radionuclides except tritium, but they are nearing capacity.
The treated water is diluted with seawater to 40th of the concentration allowed under Japanese safety standards before being released through an underwater tunnel 1 kilometer from the power plant.
According to TEPCO, no abnormal levels of tritium have been detected in the sea's nearby waters following three previous discharges.
The operator plans to skip a process after diluting the treated water from the fourth batch with seawater into a large container to make sure the tritium level is a last-minute check before releasing it.
Instead, it will take a sample of the diluted water as it is discharged, making measurements of the tritium concentration once daily.
During the discharge and for one week after its completion, the operator will take daily seawater samples from four locations within 3 km of the plant. The results will be published next day.
A total of 31,200 tons of treated wastewater is expected to be discharged in fiscal year 2023, resulting in the release of 5 trillion becquerels of tritium, or less than a quarter of the annual peak limit of 22 trillion becquerels, TEPCO said.
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