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International Nuclear Event Scale

The International Nuclear Event Scale (INES) was introduced by the International Atomic Energy Agency (IAEA) and the Nuclear Energy Agency (NEA) of the Organization for Economic Cooperation and Development (OECD) in 1990 as a tool to communicate the safety significance of reported events at nuclear installations or involving nuclear materials to the international community. Use of the INES by IAEA and OECD Member States (a number of whom have their own nuclear event classification scales) serves to promote a common understanding of the significance of reported events among governments, the nuclear community, the media and the public.

The INES consists of a 7-level event classification system. Events of greater safety significance (levels 4-7) are termed "accidents," events of lesser safety significance (levels 1-3) are termed "incidents," and events of no safety significance (level 0 or below scale) are termed "out-of-scale deviations." A description of the INES, including an explanation of the various levels can be found at the IAEA's INES web page .

The NRC does not require its licensees to classify events or to provide off-site notifications using the INES scale. The NRC has committed to transmit to the IAEA an INES-based rating for an applicable event occurring in the United States.