On 12 April 2011 , the IAEA reported that the nuclear accident at Fukushima I is now rated as a Level 7 " major accident " on the INES scale . Level 7 is the most serious level on INES and is used to describe an event consisting of " a major release of radioactive material with widespread health and environmental effects requiring implementation of planned and extended countermeasures . " Over the previous month , some scientists in the United States and the head of France 's Nuclear Safety Authority argued that the accident was , at that time , already worse than the 1979 Three Mile Island accident in Pennsylvania , which was rated a 5
Three Mile Island accident
Three Mile Island accident
International reactions to the Fukushima Daiichi nuclear disaster