Fukushima nuclear accident, Japan

Chernobyl nuclear accident, Soviet Union

Scale INES - International Nuclear Event Scale

Alert levels of the INES scale. International Nuclear Event Scale. The INES scale is a tool to quantify the severity of a nuclear and radiological event (either accidents or nuclear incidents).

INES is the acronym for International Nuclear Events Scale.

It is used worldwide to systematically inform the public about the importance of the nuclear and radiological events from the point of view of safety.

Just as the Richter scale is used to quantify the intensity of an earthquake or the Celsius scale to measure temperature, the INES scale indicates the importance of events derived from a wide range of activities, covering the industrial and medical radiation sources, the exploitation of nuclear energy facilities and transport of radioactive material.

The nuclear events can be classified into the INES scale in seven levels. The events of levels 1-3 are called "incidents", while in the case of levels 4-7 are called "accidents." Each level rise in the scale indicates that the severity of the events is approximately ten times higher. When events are not important from the point of view of safety they are called "deviations" and are classified "Below Scale / Level 0".

Description by levels of INES

Serious accident - Level 7

People and the environment

Major release of radioactive material with widespread effects on health and the environment, which requires the implementation and extension of planned countermeasures.

Major accident - Level 6

People and the environment

Significant release of radioactive material likely to require implementation of planned countermeasures.

Accident with wider consequences - Level 5

People and the environment

Limited release of radioactive material likely to require implementation of some planned countermeasures.

Several deaths from radiation.

Radiological barriers and controls

Severe damage to the reactor core.

Release of large quantities of radioactive material within an installation with a high probability of exposure to the public; possibly caused by a fire or severe criticality accident.

Accident with local consequences - Level 4

People and the environment

Minor release of radioactive material, with little likelihood of having to apply countermeasures under unless local food controls.

At least one death from radiation.

Radiological barriers and controls

Fusion fuel or fuel damage, which causes liberation top 0.1% of the core inventory.

Release of significant quantities of radioactive material within an installation with a high probability of significant public exposure.

Major incident - Level 3

People and the environment

Exposure ten times the annual limit for exposure of workers.

Effect non-lethal of radiation health (eg burns).

Radiological barriers and controls

Rates above 1 Sv / h exposure in an operating area.

Severe contamination in an area not expected by design, with a low probability of significant exposure the public.

Defense in depth

Near accident at a nuclear power plant without provision of security pending application.

Lost or stolen of highly radioactive sealed sources.

Wrong delivery of highly radioactive sealed source without adequate procedures to manipulate.

Incident - Level 2

People and the environment

Exhibition of an audience above 10 mSv.

Exposure of a worker in excess of statutory annual limits.

Radiological barriers and controls

Radiation levels exceeding 50 mSv / h in an area of operation.

Significant contamination inside a facility in an area not expected by design.

Defense in depth

Significant failures in safety provisions, but without real consequences.

Finding of an orphaned sealed source of a device or packaging for the transport of highly radioactive, indicating security arrangements, there has been no impairment.

Inadequate packaging of a highly radioactive sealed source.

Anomaly - Level 1

Defense in depth

Overexposure to an audience in excess of statutory annual limits.

Minor problems in safety components with significant defense measures pending application in depth.

Lost or stolen radioactive source, device or transport packaging of low activity.

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References

IAEA - International Atomic Energy Agency
http://www.iaea.org/Publications/Factsheets/

Last review: January 8, 2014