In a series of corporate communications and status reports issued yesterday and today, Tokyo Electric Power Co. (TEPCO) announced that several hundred tons of radioactive water that leaked from a storage tank at its Fukushima Daiichi nuclear power plant may have drained out to sea. Japan’s Nuclear Regulation Authority (NRA) proposed raising the severity status of the recent radioactive water leak from a tank at the Fukushima nuclear power plant to ‘level three’ from an earlier ‘level one,’ Japan Times reports. On the eight-level International Nuclear and Radiological Event Scale, ‘level three’ equates to a 'serious incident.'

According to the NRA, the nearly 300 tons of highly radioactive water released into the environment have been estimated to total, Japan Times states, several thousand terabecquerels; terabecquerels are a standard unit of radioactivity.

The NRA stated it will consult with the International Atomic Energy Agency (IAEA) to determine if its level assessment is appropriate since the leak occurred in the wake of the meltdown crisis. In March 2011, a tsunami resulting from an earthquake damaged reactor cooling systems and sparked three meltdowns at the plant. This accident has been recognized globally as the worst nuclear plant calamity since Chernobyl in 1986.

The IAEA issued a statement noting its awareness “of media reports” that Japan's NRA intends to categorize the leaks at ‘level three.’ "Japanese authorities continue to provide the Agency with information on the situation at the plant, and Agency experts are following the issue closely. The IAEA views this matter seriously and remains ready to provide assistance on request," the IAEA further stated. Japan Times reports that TEPCO is desperately trying to seal the tank, considered temporary and made of steel plates bolted together with sealed seams, and the energy company is “hurriedly checking” to learn if 350 similar tanks are also leaking.

Raising the severity rating would be one of the most serious actions taken since the 2011 three-reactor meltdown.

“NRA chief Shunichi Tanaka voiced deep worry Wednesday about the plant, which now has about 1,060 massive tanks containing highly radioactive water,” Japan Times reports.