The International Nuclear Event Scale
Developed by the International Atomic Energy
Association (IAEA) and the Organization for Economic
Cooperation and Development (OECD) for communicating
to the public the degree of nuclear incidents.
The scale runs from zero to seven, with zero signifying no
safety significance to seven signifying a major accident such
as Chernobyl. TMI was rated as five.
International Atomic Energy Agency, 2000