How Fukushima crisis rates on nuclear disaster scale
The nuclear crisis at Japan’s Fukushima plant is already considered the second worst nuclear accident in history, behind Chernobyl.
French experts now rate it as a six on the International Atomic Energy Agency (IAEA)’s seven-point scale, despite the Japanese insisting it remains a four.
The International Nuclear Events scale (INES) was introduced in 1990 by the IAEA to aid public understanding on the significance of such events.
The scale is designed so incidents classified at one level are 10 times more severe than those at the level below. Here is our guide:
A major accident which releases radioactive material with widespread health and environmental effects. The 1986 Chernobyl disaster in Ukraine is the only level seven incident to have taken place.
A serious accident with the likely release of significant amounts of radioactive material.
An accident with wider consequences, and several expected deaths.
An accident with local consequences and at least one death.
A serious incident in which exposure exceeds ten times the statutory annual limit for workers.
An incident in which a member of the public or a worker is exposed to a certain level and level one is an anomaly involving minor problems with safety components.