International Nuclear and Radiological Event Scale

The International Nuclear and Radiological Event Scale (INES) is used by GNPS and LNPS to classify an event occurred at the plants in accordance with its safety significant to facilitate better understanding of the event by the media and public. The INES is designed by an international group of experts convened jointly by the International Atomic Energy Agency (IAEA) and the Nuclear Energy Agency (NEA) of the Organisation for Economic Co-Operation and Development (OECD). The use of INES is monitored by the IAEA. In practice, a provisional rating may be given to an event shortly after its occurrence with confirmation at a later date. It is also possible that an event may need to be re-classified later as a result of further analysis or information. The Fukushima and Chernobyl accidents were classified at Level 7 and the Three Mile Island accident at Level 5 under the INES scale.