The International Atomic Energy Authority (IAEA) coordinates the development of the International Nuclear and Radiological Event Scale (INES) in cooperation with the OECD Nuclear Energy Authority, supported by more than 70 member states which each have an officially designated INES National Officer.
International Nuclear and Radiological Event Scale (INES)
The INES was devised in 1990 to be a worldwide means of communicating the safety significance of nuclear and radiological events to the public in a consistent manner.
The current version of the INES was adopted on July 1st 2008, and it is anticipated it will become the world wide scale for reporting such events.
Incidents that are reported using the INES range from industrial and medical use of radiation sources, operations at nuclear facilities, and the transport of radioactive material.
The INES Scale
The INES Scale is a seven point scale, with levels 1 to 3 being classified as incidents and levels 4 to 7 being classified as accidents. The INES is a logarithmic scale, which means that the severity of an event at one level is ten times greater than that of the level below it on the scale.
Events that do not have a safety significance are called deviations, and are classified as level 0.
The levels in the scale take account of three areas of impact:
- people and the environment
- radiological barriers and control
- defence in depth
The levels of the scale are defined as:
- anomaly
- incident
- Serious incident
- accident with local consequences
- Accident with wider consequences
- Serious accident
- Major accident
Chernobyl Disaster 1986: Level 7 Major Accident
The Chernobyl, Ukraine, disaster that happened on April 26th 1986 is the only level 7 event that has ever occurred. A power surge occurred during a test procedure which led to a powerful steam explosion and fire. A significant proportion of the reactor's core material was released into the environment, killing 56 people and leading to an estimated 4,000 additional cancer fatalities.
Fukushima 2011: Level 7 Major Accident
The Fukushima, Japan, accident followed the offshore earthquake of March 11th 2011, which measured 9.8 on the Richter scale, and the resultant tsunami. The reactors survived the earthquake as they were designed to do, but the tsunami damaged the backup diesel generators leading to the reactors overheating and radioactive materials being released into the environment. The accident was raised from a level 4 accident to a level 5 accident on March 18th 2011, and to a level 7 accident on April 12, 2011.
Kyshtym Disaster 1957: Level 6 Serious Accident
The Kyshtym, Russia, disaster that occurred in September 1957 is the only level 6 event that has ever occurred. The cooling system at a military nuclear waste reprocessing facility failed, causing a steam explosion that released nearly 80 tons of highly radioactive material into the environment.
Windscale 1957: Level 5 Accident with Wider Consequences
The Windscale, United Kingdom, fire that occurred on October 10th 1957 was caused when the annealing of the graphite moderator at a military air-cooled reactor caused a fire in the graphite and the metallic uranium fuel. Radioactive pile material was released as dust into the environment.
Three Mile Island 1979: Level 5 Accident with Wider Consequences
The Three Mile Island, Harrisburg, Pennsylvania, United States, accident that occurred on March 28th 1979 was caused by the combination of both design and human operator errors. They caused a gradual loss of coolant, leading to a partial meltdown, with radioactive gases being released into the atmosphere.
Sources:
International Atomic Energy Authority
International Nuclear and Radiological Event Scale
Mark Tibbits - A professional writer and educator who writes about Astrology, South Asia/China, the UK, the British Royal Family, and Religion.
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