Japan's nuclear watchdog has said it plans to upgrade the status of a radioactive water leakage from the crippled Fukushima plant, saying it is "extremely concerned." The exact source of the leak has yet to be found.
The Nuclear Regulation Authority said Wednesday it will raise the status of the leak to a level three "serious incident." The incident is currently classified as one, which means "an anomaly" on the UN's International Nuclear Event Scale (INES).
The nuclear watchdog says that before changing the leak's classification, it will consult with the UN's nuclear regulatory agency to see if using the INES to evaluate the Fukushima plant is appropriate.
The INES runs from one to seven, with seven being the worst. Only two incidents have ever been rated a seven. The first was the Chernobyl disaster a quarter century ago and the second was the Fukushima plant, which had its reactor cooling systems knocked offline by an earthquake and tsunami in 2011, causing meltdowns.
The plant's operator, the Tokyo Electric Power Co. (TEPCO), said 300 tons (300,000 liters) of contaminated water has already escaped from one of the many steel tanks surrounding it. The exact spot of the leak has yet to be found, though a faulty seam or valve is suspected.
"We are removing the soil contaminated with the leaked water, while sucking the remaining water from the troubled tank," a TEPCO spokesman said. "We are trying our best not to spread the contamination to areas outside the facility, including the sea."
TEPCO has said that the tank's location 100 meters (330 feet) from the coastline means it poses no immediate danger to the sea. However Hideka Morimoto, a spokesman for Japan's nuclear watchdog, says the radioactive water could reach the sea via a drain gutter.
"We are extremely concerned," he told reporters.
Four other tanks of the same kind, which are used to store the continuous flow of contaminated water seeping from the plant, have had leaks since last year.
TEPCO has struggled to deal with the large and ever-increasing amount of contaminated water, which is used to cool the plant's reactors. After a series of problems, the Japanese government said it would become more directly involved in the clean-up process, rather than leaving responsibility solely with the company.
dr/hc (AP, AFP, Reuters, dpa)