Fukushima Daiichi nuclear disaster on the International Nuclear Event Scale (INES). This scale runs from 0, indicating an abnormal situation with no safety consequences, to 7, indicating an accident causing widespread contamination with serious health and environmental effects. Prior to Fukushima, the Chernobyl disaster was the only level 7 event on record, while the Three Mile Island accident was rated as level 5. A 2012 analysis of the intermediate and long-lived radioactivity released found about 10–20% of that released from the Chernobyl disaster. Approximately 15 PBq of caesium-137 was released, compared with approximately 85 PBq of caesium-137 at Chernobyl, indicating the release of of
Radiation effects from the Fukushima Daiichi nuclear disaster from the Fukushima plant. Rain accumulated the caesium in the soil. Measured radioactivity per kilogram reached 250 becquerels in eastern Hokkaido, and 25 becquerels in the mountains of western Japan. According to the research group, these levels were not high enough to require decontamination. Professor Tetsuzo Yasunari of the University of Nagoya called for a national soil-testing program because of the nationwide spread of radioactive material, and suggested identified hotspots, places with high radiation levels, should be marked with warning signs. The first study concentrated on caesium-137. Around the nuclear plant, places were found containing up to 40.000 becquerels/kg, 8