According to an article in today’s New York Times, Japan has raised its assessment of the accident at the Fukushima Daiichi nuclear power plant from a 5 to a 7, indicating that this is a “major accident” that includes “major release of radioactive material with widespread health and environmental
effects requiring implementation of planned and extended countermeasures. ” A rating of 7 is the worst rating on the International Nuclear Event Scale; the only other nuclear disaster to receive a 7 was the 1986 accident at Chernobyl. The scale was developed by the International Atomic Energy Agency (IAEA).
A 4 page fact sheet about the International Nuclear Event Scale is available, although it has yet to be updated to include the Fukushima Daiichi nuclear power plant disaster.
The IAEA has been providing daily updates on Fukushima Daiichi nuclear power plant disaster since March 11.