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International Nuclear and Radiological Event Scale

The International Nuclear and Radiological 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 for promptly communicating the safety significance of reported nuclear and radiological incidents and accidents. The scale can be applied to any event associated with nuclear facilities, as well as the transport, storage and use of radioactive material and radiation sources. Use of INES serves to promote a common understanding of the significance of reported events among governments, the nuclear community, the media and the public.

Internaional Nuclear and Radiological Event Scale

The INES consists of a 7-level event classification system. Events of greater safety significance (Levels 4-7) are termed "accidents" and events of lesser safety significance (Levels 1-3) are termed "incidents." Events without safety significance are termed "deviations" and are classified below Level 0.  A description of INES, including an explanation of the various levels and a copy of the IAEA INES User’s Manual (2008 edition) can be found at NRC’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 according to the agreed criteria in “The International Nuclear and Radiological Event Scale (INES) User’s Manual, 2008 Edition” which are— (a) Events rated at level 2 or above, or (b) Events attracting international public interest.

Page Last Reviewed/Updated Thursday, May 15, 2014