Tepco starts releasing second batch of treated radioactive water from Fukushima nuclear plant

Tokyo Electric Power Company (Tepco) started releasing more treated radioactive water from the wrecked Fukushima Daiichi Nuclear Power Plant on Thursday morning, continuing a move that has caused tensions between China and Japan.

The release will last for about 17 days starting Thursday, during which some 7,800 cubic metres of wastewater will be released into the Pacific Ocean.

Nuclear authorities, including the United Nations nuclear watchdog, have said the plan will have a negligible impact on humans and the environment, but it has still angered some neighbours, especially China.

The initial release of the water in late August triggered a blanket ban on Japanese seafood products by China and a deluge of harassment calls to businesses and offices, believed to originate from China.

Junichi Matsumoto, who is overseeing the water release at Tepco, said on Wednesday during a news conference that Tepco had received more than 6,000 calls from abroad between August 24-27. Many appeared to originate from China, but Tepco did not track the exact number of such calls.

Japan started the water discharge in August in a key step towards decommissioning the Fukushima plant, which suffered meltdowns after being hit by a tsunami in 2011 in the world's worst nuclear plant disaster since Chernobyl 25 years earlier.

Japan says the water is treated to remove most radioactive elements except tritium, a hydrogen isotope that must be diluted because it is difficult to filter.

Tritium levels in the surrounding waters since the initial discharge have met pre-determined standards, according to tests conducted by Tepco, and no issues have been identified with the first water release, Matsumoto said.