The Japanese government raised its assessment of the month-long crisis at its Fukushima Daiichi nuclear power plant to the highest severity level by international standards. The rating only conferred so far upon the Chernobyl accident.
The accident’s severity rating on the International Nuclear Event scale was raised to a 7 from 5, the same level reached by the Chernobyl nuclear disaster in the former Soviet Union, which struck almost exactly 25 years ago, on April 26, 1986.
The International Nuclear Event scale, whose development is coordinated by the International Atomic Energy Agency, measures the severity of accidents based on how much radiation is released, the degree of damage to the nuclear cores and how widespread and long-lasting the effects are likely to be.
