The operator of the crippled Fukushima Daiichi nuclear power plant on Friday started a sixth release of treated radioactive water into the sea amid opposition from China and Russia.

Tokyo Electric Power Company Holdings Inc. said it plans to discharge 7,800 tons of water through June 4, after confirming that the radioactivity levels meet both its own and the government's standards.

File photo taken from a drone on March 4, 2024, shows the Fukushima Daiichi nuclear power station in Fukushima Prefecture. (Kyodo)

Since the operation began on Aug. 24 last year, about 39,000 tons of treated water have been released over five previous rounds. The utility plans to discharge a total of about 54,600 tons on seven occasions this fiscal year, which started in April.

During the release of the previous five batches, TEPCO said it detected up to 29 becquerels of radioactive tritium per liter of seawater in samples taken from areas near the power complex, well below the World Health Organization's limit of 10,000 becquerels for drinking water.

China and Russia, which oppose the water release due to safety concerns, have banned Japanese seafood imports in response to the discharges.

The utility sees the discharge as a key step in the ongoing decommissioning of the Fukushima Daiichi plant, which suffered fuel meltdowns in three reactors following a massive earthquake and tsunami in 2011.

The wastewater, generated in the process of cooling melted reactor fuel, has gone through a liquid processing system that removes most radionuclides except tritium, considered less harmful than other radioactive materials.

==Kyodo