Nuclear Power Plant Isar, Germany

Spent nuclear fuel pool

Turbine of a nuclear plant

How Are Nuclear Accidents Classified?

A nuclear accident is an accident that causes or could cause the release of radioactive material.

How are nuclear accidents classified?

There are many ways to classify this type of event. In a very simple first classification we could distinguish between civil nuclear accidents and nuclear accidents of military origin.

Within the scope of civil nuclear technology, not all nuclear accidents occur in nuclear power plants. Nuclear disasters can be generated in any field that works with this technology: hospitals, research centers, etc.

Another way to classify nuclear accidents is according to their severity and the consequences generated. In this sense, the INES scale was created.

INES Scale

To determine the severity of a nuclear accident, a scale with seven levels was created, with the highest value implying greater severity. This scale is the well-known INES scale.

The INES scale or international scale of nuclear and radiological events (International Scale of Nuclear and Radiological Events) has been developed since 1989 by the IAEA, the international atomic energy agency, with the objective of classifying nuclear and radiological accidents and allowing The severity of nuclear or radiological accidents is immediately noticeable to the public, without referring to technical data that is more difficult to understand.

The INES scale applies to events associated with the transport, storage and use of radioactive materials or sources, regardless of whether the event occurs in an industrial plant or abroad (for example, during transport).

The INES scale includes 7 levels (plus a level 0 below the scale) and is divided into two parts: the incidents (from the 4th to the 7th level) and the failures (from the 1st to the 3rd). Level 0 is classified as a diversion. It is a logarithmic scale and, therefore, the passage from one level to another means an increase in damage of approximately ten times.

So far the two most serious nuclear accidents have been the Chernobyl nuclear accident and the Fukushima nuclear disaster. Both were classified at level 7 on the INES scale.


Published: January 25, 2020
Last review: January 24, 2020