Nuclear power plant accidents: listed and ranked since 1952

But how serious are they? The International Atomic Energy Authority ranks them using a special International Nuclear Events Scale (INES) – ranging from ‘anomaly’ to ‘major accident’, numbered from 1 to 7.

The events at Fukushima are level 5, so far and there has only been one 7 in history: Chernobyl in 1986. You can see the full ranking system below and on the attached spreadsheet