Leak of toxic water at Fukushima nuclear plant

The operator of the ruined Fukushima Daiichi nuclear plant has said highly toxic water is leaking from a storage tank, the latest problem to plague the immensely complex clean-up of the facility.

Tokyo Electric Power Co (Tepco) said the leak of about 300 tonnes is the most serious since a huge earthquake and tsunami knocked out power to the plant’s cooling system in March 2011.

Masked workers found puddles with radiation of 100 millisieverts an hour near makeshift tanks that store contaminated water – enough to induce radiation sickness in less than 12 hours. “This means you are exposed to the level of radiation in an hour that a nuclear plant worker is allowed to be exposed to in five years,” a Tepco spokesman said yesterday.

The news follows the recent admission that the complex is leaking 300 tonnes of radioactive water per day into the Pacific. Japan’s Nuclear Regulation Authority (NRA) said it could not rule out the possibility that the leak had been going on since the disaster started 30 months ago. Tepco had denied the leak for months.

Last week, it said a team of workers had been accidently sprayed with contaminated water. Work at the plant has been dogged by power failures and technical problems that have underlined the difficulties of cleaning up from the world's worst nuclear disaster since the 1986 Chernobyl accident.

Cover-up
"The situation is getting worse," Michiaki Furukawa, a nuclear chemist told reporters. Many experts believe Japan's government continues to underestimate the cost and complexity of the decommissioning, and that Tepco has been systematically covering up problems.

Tepco insisted yesterday that the latest leak had not reached the ocean, about 500m away. But it said it had yet to pinpoint exactly where the water was coming from and added only four tonnes has been recovered and returned to a sealed tank. An NRA official told reporters yesterday there had been no detectable rise in radiation levels outside the plant complex.

Engineers are pouring hundreds of tonnes of water a day on to melted uranium fuel rods at the plant to keep them from overheating. The toxic water is stored in more than 1,000 huge onsite tanks, awaiting decontamination. The joints of the makeshift tanks are sealed with plastic and prone to leaks.

The string of setbacks and growing public alarm forced the government last week to promise it would get more directly involved in the effort to dismantle the six-reactor plant. “It is an urgent problem,” prime minister Shinzo Abe said, promising a fresh government strategy to end the crisis.

Tepco engineers are trying to build an artificial underground wall between the plant and the Pacific in a bid to stop radioactive groundwater from reaching the sea. The leaks have become a diplomatic issue: Japan’s neighbour South Korea again publicly expressed concern this week about the impact of the contamination on fishing stocks.