Six workers have been splashed with highly radioactive water after mistakenly detaching a hose of a treatment system in the newest mishap at the crippled Fukushima power plant.
According to Tokyo Electric Power Company (Tepco), 7 tonnes of water with radiation levels of 34 million becquerels per litre escaped from the salt-removing system. However, authorities have said the radiation dosage wasn’t dangerous for the exposed workers.
"It is serious in that it was another problem caused by carelessness, but I do not believe it is a seriously troubling dosage," Shunichi Tanaka, chairman of Japan's Nuclear Regulation Authority, said on Wednesday.
"But the fact that there has been a string of incidents occurring on a daily basis that could have been avoided – I think that is the large problem."
Tepco has been struggling to contain radioactive water at the plant ever since the March 2011 earthquake, which resulted in triple meltdowns and hydrogen explosions.
Tanaka urged Tepco to improve its handling of contaminated water, but stopped short of saying if it faced any penalties.
Tanaka said the leaked water has already been treated to remove caesium, which emits strong gamma radiation harmful to humans.
Earlier this week, Tepco admitted a plant worker accidentally halted power to pumps used to cool the damaged reactors. A backup system kicked in immediately, but the event was another reminder of the precarious situation at the plant.
Last week, Tepco said 430 litres of contaminated water had spilled out of a storage tank at Fukushima and probably flowed to the ocean.
Japan's nuclear regulator said on Wednesday that the incident was equivalent to "Level 0" on the International Nuclear and Radiological Events Scale (INES), but gave no official rating.
In August, a leak of 300 tonnes of highly radioactive water from a hastily built site tank was given a "Level 3" or "serious incident" rating on the INES scale.
Tepco has been criticised by the Japanese government and the country’s Nuclear Regulation Authority for sloppy handling of the situation and was urged to improve its clean-up strategy.
Despite doubts over Tepco’s abilities being stirred by the company’s failure to keep the situation under control, Tepco plans to restart its only remaining viable plant – Kashiwazaki Kariwa, the world's largest nuclear power station, to cut high fuel costs and restore its finances.