Level 4 nuclear emergency / classifications: America (NRC) vs. International (INES)

There are rumors that Fort Calhoun Nuclear Plant in Nebraska is under a Level 4 emergency classification. Fort Calhoun is currently under a “Notification of Unusual Event (NOUE)” — which is the 4th (and lowest) emergency classification in the US. This is completely different from a Level 4 event on the International Nuclear and Radiological Event Scale (INES). There’s a HUGE difference between the NRC’s Emergency Classifications and the INES’s Emergency Classifications.

Neither Fort Calhoun or Cooper Nuclear Station are being classified by the INES scale. (NOTE: Fort Calhoun was on “Alert” classification in addition to the NOUE classification  for one day this month.) Here are the definitions and links:

Emergency Classification in America:

Emergency Classification is a set of plant conditions which indicate a level of risk to the public. Nuclear power plants use the four emergency classifications listed below in order of increasing severity.

  • Notification of Unusual Event - Under this category, events are in process or have occurred which indicate potential degradation in the level of safety of the plant. No release of radioactive material requiring offsite response or monitoring is expected unless further degradation occurs.
  • Alert - If an alert is declared, events are in process or have occurred that involve an actual or potential substantial degradation in the level of safety of the plant. Any releases of radioactive material from the plant are expected to be limited to a small fraction of the Environmental Protection Agency (EPA) protective action guides (PAGs).
  • Site Area Emergency - A site area emergency involves events in process or which have occurred that result in actual or likely major failures of plant functions needed for protection of the public. Any releases of radioactive material are not expected to exceed the EPA PAGs except near the site boundary.
  • General Emergency - A general emergency involves actual or imminent substantial core damage or melting of reactor fuel with the potential for loss of containment integrity. Radioactive releases during a general emergency can reasonably be expected to exceed the EPA PAGs for more than the immediate site area.


The International Nuclear and Radiological Event Scale (INES):

Level 4: Accident with local consequences:

Impact on people and environment: 

Minor release of radioactive material unlikely to result in implementation of planned countermeasures other than local food controls.

At least one death from radiation.

Impact on radiological barriers and control:

Fuel melt or damage to fuel ­resulting in more than 0.1% release of core inventory.

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


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