INES levels
The International Nuclear Event Scale (INES), which comprises seven levels, is now applied throughout the world.
An incident is an event in which a plant deviates from operation as specified, with impairment of its safety. To ensure that the nature and level of severity of incidents in nuclear power plants are universally described in the same way, the International Atomic Energy Agency (IAEA), together with the Organisation for Economic Co-operation and Development (OECD), have developed an international event scale for nuclear plants.