Japan ups Fukushima threat warning

Japan will dramatically raise its warning about the severity of a toxic water leak at the Fukushima nuclear plant, its nuclear watchdog said Wednesday, its most serious action since the plant was destroyed by an earthquake and tsunami in 2011.

The deepening crisis at the Fukushima plant will be upgraded from a level 1 "anomaly" to a level 3 "serious incident" on an international scale for radiological releases, a spokesman for Japan's Nuclear Regulation Authority (NRA) said.

That will mark the first time Japan has issued a warning on the International Nuclear Event Scale (INES) since three reactor meltdowns after the massive quake in March 2011.

The new warning comes less than 24 hours after Fukushima operators Tokyo Electric Power Co. (TEPCO) revealed a steel storage tank had leaked 300 metric tons of radioactive water, and less than two weeks after the company announced an additional 300 tons of contaminated water were spilling into the sea daily.

Japan's nuclear regulator said it believed more tanks were leaking contaminated water, and also said it feared the disaster exceeded the ability of the plant's operator to cope "in some respects".

A maximum level 7 was declared at the battered plant after explosions led to a loss of power and cooling two years ago, confirming Fukushima as the worst nuclear accident since Chernobyl a quarter of a century earlier.

Contaminated water with dangerously high levels of radiation is leaking from a storage tank at Fukushima, TEPCO said on Tuesday. The leak was classified as an "anomaly" earlier this week.

The NRA's impending assessment upgrade came in a document posted on the agency's website on Wednesday, with formal adoption to follow a meeting that is being held by the authority's commissioners, the NRA spokesman said by telephone.

"Judging from the amount and the density of the radiation in the contaminated water that leaked ... a level 3 assessment is appropriate," the document said.

Each step up the INES incident scale represents a tenfold increase in severity, according to a factsheet on the website of the International Atomic Energy Agency. The level 3 rating is assigned when there is exposure of more than 10 times the limit for workers, according to the factsheet.

Level 3 is the highest stage than can still be termed an "incident." Level 4 and above are each classified as an "emergency."

The leak, which has not been plugged, is so contaminated that a person standing 1.6 feet away would, within an hour, receive a radiation dose five times the average annual global limit for nuclear workers.

After 10 hours, a worker in that proximity to the leak would develop radiation sickness with symptoms including nausea and a drop in white blood cells.

Al Jazeera and Reuters