Tokyo: Tokyo Electric Power Company Holdings Inc. on Thursday started the third round of treated water release from its meltdown-stricken Fukushima No. 1 nuclear power plant into the ocean.

As in the first and second rounds, conducted between August and October, TEPCO will dilute some 7,800 tons of the treated water, which still contains tritium, a radioactive substance, with a large amount of seawater before releasing it at a point about 1 kilometer off the coast via an underground tunnel.

The third round will run until Nov. 20. The fourth round of treated water release is expected to be conducted early next year or later.

By the March 31 end of fiscal 2023, a total of 31,200 tons of treated water will be released into the Pacific from the nuclear plant in Fukushima Prefecture, northeastern Japan.

But TEPCO expects that it will take about 30 years to complete the mission because treated water is generated continuously at the plant, which was severely damaged in the March 2011 powerful earthquake and tsunami.

After the end of the second round, TEPCO examined related facilities including the pipework and a pump for any abnormality. The company checked by Wednesday some of the diluted water before discharge and confirmed that the concentration of tritium was below its voluntary safety standards.

TEPCO checks the tritium concentration in nearby waters every day. Also, the Environment Ministry and others including the Fisheries Agency conduct inspections of seawater sampled and aquatic products caught off the plant.

These inspections confirmed that the tritium concentration levels were substantially below the state standards.

JIJI Press