What is the International Nuclear Event Scale? Wildlife & Humanity Explored

What is the International Nuclear Event Scale? 

The International Nuclear and Radiological Event Scale (INES) was introduced in 1990[1] by the International Atomic Energy Agency (IAEA) in order to enable prompt communication of safety significant information in case of nuclear accidents. 

However, considering that it can be difficult to interpret during a disaster, the disaster’s level is typically assigned long AFTER a nuclear disaster has occured. 

The scale ranges from 0 to 7, 0 representing a problem with no safety significance, and 7 representing a nuclear disaster akin to that of Chernobyl.

For more information on the Chernobyl disaster, check out our YouTube video on the subject right HERE, which has garnered over 800k views as of September 2020! 

In today’s post, we will be exploring the INES scale in depth, as well as examples of what has occurred at each level. 

Check out the video version of this post by clicking right HERE now. 

You can also download the radiation-free audio-only podcast by clicking HERE. 

Before Proceeding: Important Note About the Scale

The scale is “logarithmic.” This means that it grows “exponentially.” 

For example, going from a level 6 to level 7 disaster isn’t the same as going from “60 cookies” to “70 cookies.” The change would be the equivalent of going from “60 cookies” to “600 cookies.” 

Therefore changes in one level are extreme and highly dangerous. 

Radiation & Wildlife

Nuclear disasters like Chernobyl have severe effects on humanity and wildlife. A little radiation can turn a beautiful forest into a desolate wasteland, or a thriving city into a ghost town. 

While the Chernobyl exclusion zone isn’t too large today and doesn’t affect anyone too much, the initial effects during the disaster were far-reaching, with contamination spreading to several countries in Europe. 

This most famous nuclear disaster has prompted extreme safety concerns and focus in order to prevent future accidents from spreading. 

While wildlife has returned to the high-radiation Chernobyl exclusion zone, it is nothing of its former glory, and many wild animals suffer from deformities and sickness due to sudden mutations in genes. 

Now let’s take a look at the range of nuclear disasters and how they can affect wildlife: 

Level 0: Deviation

A deviation is a problem which holds “no safety significance.” There is no damage caused to humans, the plant, or wildlife nearby. 

Level 1: Anomaly

An anomaly on this scale represents a few different issues such as: 

  • Overexposure of a member of the public in excess of statutory annual limits.
  • Minor problems with safety components with significant defence-in-depth remaining.
  • Low activity lost or stolen radioactive source, device or transport package.

These are dangerous situations that typically have no severe consequences. 

Level 2: Incident

Incidents are when the danger level starts to pick up. Some things that can be classified as incidents include: 

  • Exposure of a member of the public in excess of 10 mSv (the level of radiation inside them) 
  • Exposure of a worker in excess of the statutory annual limits.
  • Significant contamination or abnormally high radiation levels within the facility not expected or designed for

Here are 2 examples of an “incident” occurring: 

  • Sellafield Magnox Reprocessing Facility (United Kingdom) 2017; confirmed exposure to radiation of individuals which exceed or are expected to exceed, the dose limits (2 incidents in this year).[21]
  •     Gundremmingen Nuclear Power Plant (Germany) 1977; weather caused short-circuit of high-tension power lines and rapid shutdown of reactor

Level 3: Serious Incident

While a level 2 incident isn’t that severe for the public, level 3 is when things reach dangerous levels for public safety. 

Some of the impacts of a serious incident on the people & environment include: 

  • Exposure in excess of ten times the statutory annual limit for workers.
  • Non-lethal deterministic health effects (e.g., burns) from radiation.

Some things which can cause it: 

  • Near-accident at a nuclear power plant with no safety provisions remaining.
  • Lost or stolen highly radioactive sealed source.
  • Misdelivered highly radioactive sealed source without adequate procedures in place to handle it.

2 Examples of a serious incident: 

  • THORP plant, Sellafield (United Kingdom), 2005; very large leak of a highly radioactive solution held within containment.
  • Vandellòs I Nuclear Incident in Vandellòs (Spain), 1989; fire destroyed many control systems; the reactor was shut down.

Level 4: Accident with Local Consequences

The impact of a level 4 accident typically involves at least one human death. According to the official scale, here’s the impact on wildlife & humans: 

  • Minor release of radioactive material unlikely to result in implementation of planned countermeasures other than local food controls.
  • At least one death from radiation exposure
  • Release of significant quantities of radioactive material within an installation with a high probability of significant public exposure.

Some examples of a level 4 accident include: 

  • Tokaimura nuclear accident (Japan) – 1999, three inexperienced operators at a reprocessing facility caused a criticality accident; two of them died.[11]
  • Mayapuri (India) – 2010, a university irradiator was sold for scrap and dismantled by dealers unaware of the hazardous materials.
  • Buenos Aires (Argentina) – 1983, criticality accident on research reactor RA-2 during fuel rod rearrangement killed one operator and injured two others.

Level 5: Accident with Wider Consequences

This is when things start to get severe and can affect the public from farther away: 

Some of the impacts on wildlife and humans include: 

  • Limited release of radioactive material likely to require implementation of some planned countermeasures.
  • Several deaths from radiation.

What “planned countermeasures” specifically means is a coordinated plan to fight the radiation and hazard. 

Some examples of this level of incident include: 

Level 6: Serious Accident

The big differentiator between level 5 and level 6 is that level 6 requires serious countermeasures and organized efforts of the government and people in order to contain and fix the damage that was caused. 

Note: this was NOT the level of the Chernobyl incident…

According to the scale a level 6 accident IS “Significant release of radioactive material likely to require implementation of planned countermeasures.”

As of September 2020 there has only been one level 6 accident: 

Kyshtym disaster at Mayak Chemical Combine (MCC) Soviet Union, 29 September 1957. A failed cooling system at a military nuclear waste reprocessing facility caused an explosion with a force equivalent to 70–100 tons of TNT.[10] About 70 to 80 metric tons of highly radioactive material were carried into the surrounding environment. The impact on the local population is not fully known, however reports of a unique condition known as chronic radiation syndrome is reported due to the moderately high dose rates that 66 locals were continually exposed to. At least 22 villages were evacuated.

Level 7: Major Accident

A level 7 major accident is Major release of radioactive material with widespread health and environmental effects requiring implementation of planned and extended countermeasures.

To date, there have only been 2 level 7 major accidents, and it’s likely that you’ve heard of both of them. 

Chernobyl disaster, 26 April 1986. Unsafe conditions during a test procedure resulted in a 
criticality accident, leading to a powerful steam explosion and fire that released a significant fraction of core material into the environment, resulting in an eventual death toll of 4,000-93,000.[2][3][3][4][5][6] As a result of the plumes of radioisotopes, the city of Chernobyl (pop. 14,000) was largely abandoned, the larger city of Pripyat (pop. 49,400) was completely abandoned, and a 30 kilometres (19 mi) exclusion zone around the reactor was established

Fukushima Daiichi nuclear disaster, a series of events beginning on 11 March 2011. Major damage to the backup power and containment systems caused by the 2011 Tōhoku earthquake and tsunami resulted in overheating and leaking from some of the Fukushima I nuclear plant's reactors.[7] A temporary exclusion zone of 20 kilometres (12 mi) was established around the plant,[8] and officials considered evacuating Tokyo, Japan's capital and the world's most populous metropolitan area, 225 kilometres (140 mi) away. 


The International Nuclear Event Scale determines just how severe a particular nuclear accident was. 

The 2 level 7 incidents in history - Fukushima & Chernobyl - have prompted extreme safety measures in order to prevent this level of accident from ever happening again. 

Level 7 incidents have the potential to vastly change regions of the Earth, as seen in the Chernobyl exclusion zone. While nuclear power is great, it’s important that we as a species use this power wisely. 

Got Wildlife or Pests? 

While it’s important to live radiation-free, it’s also important to keep your home free of wildlife and pests. 

Contact us at 855-WILDLIFE or by visiting www.wildlifexteam.com if you think that you have an animal or pest infestation inside of or near your home.

We will be sure to safely remove the wildlife, restore it to the wild, undo the damage caused, and prevent it from happening again - all radiation free! 

-Wildlife x Team International 


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