International Nuclear and Radiological Event Scale

The international nuclear event scale is used to communicate the safety significance of nuclear and radiological events to the public.

The International Nuclear and Radiological Event Scale (INES) is a seven point scale, with Level 1 being the least significant, and Level 7 the most significant. Where an event is classified as Level 0 or ‘below scale’, this means it has no nuclear or radiological safety significance. 

The International Nuclear and Radiological Event Scale (INES) is a seven point scale, with Level 1 being the least significant, and Level 7 the most significant. Where an event is classified as Level 0 or ‘below scale’, this means it has no nuclear or radiological safety significance.

INES classifies nuclear and radiological accidents and incidents by considering three areas of impact:

  • People and the Environment considers the radiation doses to people close to the location of the event and the widespread, unplanned release of radioactive material from an installation.
  • Radiological Barriers and Control covers events without any direct impact on people or the environment and only applies inside major facilities. It covers unplanned high radiation levels and spread of significant quantities of radioactive materials confined within the installation.
  • Defence-in-Depth also covers events without any direct impact on people or the environment, but for which the range of measures put in place to prevent accidents did not function as intended.

Information on recent events and their INES rating is available from IAEA NEWS service.