The Nuclear and Industrial Safety Agency on Friday raised its assessment of the situation at the Fukushima No. 1 nuclear power plant to 5 on the 7-level International Nuclear and Radiological Event Scale (INES).
The Nuclear and Industrial Safety Agency on Friday raised its assessment of the situation at the Fukushima No. 1 nuclear power plant to 5 on the 7-level International Nuclear and Radiological Event Scale (INES).
The level 5 ranking, which is defined as an "accident with wider consequences," was given to the Three Mile Island nuclear plant accident of 1979.
NISA officials said the severity level at the Fukushima plant was raised a notch because large amounts of radioactive materials were released within the No. 1 to No. 3 reactors, and the possibility is high that the reactor cores had been damaged.
The previous highest INES ranking in Japan was level 4 for the criticality accident at a Tokai, Ibaraki Prefecture, facility of JCO Co., a nuclear fuel reprocessing company. A level 4 ranking means an "accident with local consequences."
The highest ranking of level 7, or a "major accident," was given to the Chernobyl nuclear disaster of 1986.