As Smythe pointed out , the INES scale ends at 7 ; a more severe accident than Fukushima in 2011 or Chernobyl in 1986 can not be measured by that scale . In addition , it is not continuous , not allowing a fine-grained comparison of nuclear incidents and accidents . But then , the most pressing item identified by Smythe is that INES conflates magnitude with intensity ; a distinction long made by seismologists to describe earthquakes . In that area , magnitude describes the physical energy released by an earthquake , while the intensity focuses on the effects of the earthquake . In analogy , a nuclear incident with a high magnitude ( e.g. a core meltdown ) may not result in an intense radioactive contamination , as the incident at the Swiss research reactor in Lucens shows – but yet it resides in INES category 5 , together with the Windscale fire of 1957 , which has caused significant contamination outside of the facility
Windscale fire
Windscale fire
International Nuclear Event Scale