Japan's nuclear safety agency has formally raised the severity level of the crisis at the earthquake and tsunami-hit Fukushima Daiichi nuclear power plant to the highest level of 7 -- equal to the severity of the 1986 disaster at Chornobyl in the former Soviet Union.
The Japanese disaster has until now been rated at level 5 on the International Nuclear And Radiological Event Scale -- the same as the 1979 incident at Three Mile Island in the United States.
According to the international scale, level 7 incidents are ones with a "major release of radioactive material with widespread health and environmental effects."
Japan's Nuclear And Industrial Safety Agency said it estimates that the amount of radioactive materials released so far from Fukushima are only about 10 percent of what was eventually emitted from Chornobyl in Ukraine.
"Based on data we've collected since March 18th, we've given this a preliminary rating of seven,” Hidehiko Nishiyama, a senior official of the agency, told a news conference in Tokyo. “However, the emission of radioactive substances is about 10 percent of the amount of Chornobyl, which is rated at a similar level."
Reactors at the Fukushima plant have been releasing radioactive substances into the air and surrounding Pacific Ocean since cooling systems were knocked out by the March 11 9.0-magnitude earthquake and subsequent tsunami that devastated Japan.
compiled from agency reports