INES scale
INES - International Nuclear Event Scale is designed to enable prompt communication to the public of safety significance information in case of nuclear 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.
How INES scale was created. The scale was designed by an international group of experts first convened jointly in 1989 by the IAEA and the Nuclear Energy Agency of the Organisation for Economic Co-operation and Development - OECD/NEA. Since then, the IAEA has overseen its development in cooperation with the OECD/NEA and with the support of more than 70 designated INES National Officers who officially represent the INES Member States in biennial technical meetings.
Why use INES. INES, to facilitate understanding, uses a numerical rating to explain the significance of nuclear or radiological events. This is just like using ratings for earthquakes or temperature, which would be difficult to understand without the Richter or Celsius scales.
INES applies to any event associated with the transport, storage and use of radioactive material and radiation sources. Such events can include industrial and medical uses of radiation sources, operations at nuclear facilities, or the transport of radioactive material.
Seven levels of classification. Events are classified at seven levels:
- major accident (level 7)
- serious accident (level 6)
- accident with wider consequences (level 5)
- accident with local consequences (level 4)
- serious incident (level 3)
- incident (level 2)
- anomaly (level 1)
These levels consider three areas of impact: people and the environment, radiological barriers and control, and defence in depth. The scale is designed so that the severity of an event is about ten times greater for each increase in level on the scale. Events without safety significance are called “deviations” and are classified Below Scale/Level 0.
(Image: IAEA web site)