![INES en](https://upload.wikimedia.org/wikipedia/commons/2/24/INES_en.svg)
The International Nuclear and Radiological Event Scale (INES) was introduced in 1990 by the
International Atomic Energy Agency
The International Atomic Energy Agency (IAEA) is an intergovernmental organization that seeks to promote the peaceful use of nuclear energy and to inhibit its use for any military purpose, including nuclear weapons. It was established in 1957 ...
(IAEA) in order to enable prompt communication of
safety
Safety is the state of being "safe", the condition of being protected from harm or other danger. Safety can also refer to risk management, the control of recognized hazards in order to achieve an acceptable level of risk.
Meanings
There are ...
significant information in case of
nuclear accident
A nuclear and radiation accident is defined by the International Atomic Energy Agency (IAEA) as "an event that has led to significant consequences to people, the environment or the facility. Examples include lethal effects to individuals, lar ...
s.
The scale is intended to be
logarithmic, similar to the
moment magnitude scale
The moment magnitude scale (MMS; denoted explicitly with or Mw, and generally implied with use of a single M for magnitude) is a measure of an earthquake's magnitude ("size" or strength) based on its seismic moment. It was defined in a 1979 pape ...
that is used to describe the comparative magnitude of earthquakes. Each increasing level represents an accident approximately ten times as severe as the previous level. Compared to earthquakes, where the event intensity can be quantitatively evaluated, the level of severity of a
man-made disaster
Anthropogenic hazards are hazards caused by human action or inaction. They are contrasted with natural hazards. Anthropogenic hazards may adversely affect humans, other organisms, biomes, and ecosystems. They can even cause an omnicide. The fre ...
, such as a nuclear accident, is more subject to interpretation. Because of this subjectivity the INES level of an incident is assigned well after the fact. The scale is therefore intended to assist in disaster-aid deployment.
Details
A number of criteria and indicators are defined to assure coherent reporting of
nuclear events by different official authorities. There are seven nonzero levels on the INES scale: three ''
incident
Incident may refer to:
* A property of a graph in graph theory
* ''Incident'' (film), a 1948 film noir
* Incident (festival), a cultural festival of The National Institute of Technology in Surathkal, Karnataka, India
* Incident (Scientology), a ...
''-levels and four ''
accident
An accident is an unintended, normally unwanted event that was not directly caused by humans. The term ''accident'' implies that nobody should be blamed, but the event may have been caused by unrecognized or unaddressed risks. Most researcher ...
''-levels. There is also a level 0.
The level on the scale is determined by the highest of three scores: off-site effects, on-site effects, and
defense in depth
Defence in depth (also known as deep defence or elastic defence) is a military strategy that seeks to delay rather than prevent the advance of an attacker, buying time and causing additional casualties by yielding space. Rather than defeating ...
degradation.
Out of scale
There are also events of no safety relevance, characterized as "out of scale".
:Examples:
:* 5 March 1999:
San Onofre, United States: Discovery of suspicious item, originally thought to be a bomb, in nuclear power plant.
:* 29 September 1999:
H.B. Robinson, United States: A tornado sighting within the protected area of the
nuclear power plant
A nuclear power plant (NPP) is a thermal power station in which the heat source is a nuclear reactor. As is typical of thermal power stations, heat is used to generate steam that drives a steam turbine connected to a electric generator, generato ...
.
:* 17 November 2002, Natural Uranium Oxide Fuel Plant at the
Nuclear Fuel Complex in Hyderabad, India: A chemical explosion at a fuel fabrication facility.
Criticism
Deficiencies in the existing INES have emerged through comparisons between the 1986
Chernobyl disaster
The Chernobyl disaster was a nuclear accident that occurred on 26 April 1986 at the No. 4 reactor in the Chernobyl Nuclear Power Plant, near the city of Pripyat in the north of the Ukrainian SSR in the Soviet Union. It is one of only two nuc ...
, which had severe and widespread consequences to humans and the environment, and the 2011
Fukushima Daiichi nuclear accident
The was a nuclear accident in 2011 at the Fukushima Daiichi Nuclear Power Plant in Ōkuma, Fukushima, Japan. The proximate cause of the disaster was the 2011 Tōhoku earthquake and tsunami, which occurred on the afternoon of 11 March 2011 a ...
, which caused no fatalities and comparatively small (10%) release of radiological material into the environment. The Fukushima Daiichi nuclear accident was originally rated as INES 5, but then upgraded to INES 7 (the highest level) when the events of units 1, 2 and 3 were combined into a single event and the combined release of radiological material was the determining factor for the INES rating.
One study found that the INES scale of the IAEA is highly inconsistent, and the scores provided by the IAEA incomplete, with many events not having an INES rating. Further, the actual accident damage values do not reflect the INES scores. A quantifiable, continuous scale might be preferable to the INES, in the same way that the antiquated
Mercalli scale
The Modified Mercalli intensity scale (MM, MMI, or MCS), developed from Giuseppe Mercalli's Mercalli intensity scale of 1902, is a seismic intensity scale used for measuring the intensity of shaking produced by an earthquake. It measures the eff ...
for earthquake magnitudes was superseded by the continuous physically-based
Richter scale
The Richter scale —also called the Richter magnitude scale, Richter's magnitude scale, and the Gutenberg–Richter scale—is a measure of the strength of earthquakes, developed by Charles Francis Richter and presented in his landmark 1935 ...
.
The following arguments have been proposed: firstly, the scale is essentially a discrete qualitative ranking, not defined beyond event level 7. Secondly, it was designed as a public relations tool, not an objective scientific scale. Thirdly, its most serious shortcoming is that it conflates magnitude and intensity. An alternative nuclear accident magnitude scale (NAMS) was proposed by British nuclear safety expert
David Smythe to address these issues.
Nuclear Accident Magnitude Scale
The Nuclear Accident Magnitude Scale (NAMS) is an alternative to INES, proposed by David Smythe in 2011 as a response to the
Fukushima Daiichi nuclear disaster
The was a nuclear accident in 2011 at the Fukushima Daiichi Nuclear Power Plant in Ōkuma, Fukushima, Japan. The proximate cause of the disaster was the 2011 Tōhoku earthquake and tsunami, which occurred on the afternoon of 11 March 2011 and ...
. There were some concerns that INES was used in a confusing manner, and NAMS was intended to address the perceived INES shortcomings.
As Smythe pointed out, the INES scale ends at 7; a more severe accident than Fukushima in 2011 or
Chernobyl
Chernobyl ( , ; russian: Чернобыль, ) or Chornobyl ( uk, Чорнобиль, ) is a partially abandoned city in the Chernobyl Exclusion Zone, situated in the Vyshhorod Raion of northern Kyiv Oblast, Ukraine. Chernobyl is about no ...
in 1986 would also be measured as INES category 7. In addition, it is not continuous, not allowing a fine-grained comparison of nuclear incidents and accidents. But then, the most pressing item identified by Smythe is that INES conflates magnitude with intensity; a distinction long made by
seismologist
Seismology (; from Ancient Greek σεισμός (''seismós'') meaning "earthquake" and -λογία (''-logía'') meaning "study of") is the scientific study of earthquakes and the propagation of elastic waves through the Earth or through other ...
s to describe
earthquake
An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from ...
s. In that area,
magnitude
Magnitude may refer to:
Mathematics
*Euclidean vector, a quantity defined by both its magnitude and its direction
*Magnitude (mathematics), the relative size of an object
*Norm (mathematics), a term for the size or length of a vector
*Order of ...
describes the physical energy released by an earthquake, while the
intensity
Intensity may refer to:
In colloquial use
*Strength (disambiguation)
*Amplitude
* Level (disambiguation)
* Magnitude (disambiguation)
In physical sciences
Physics
*Intensity (physics), power per unit area (W/m2)
*Field strength of electric, ma ...
focuses on the effects of the earthquake. In analogy, a nuclear incident with a high magnitude (e.g. a core meltdown) may not result in an intense
radioactive contamination
Radioactive contamination, also called radiological pollution, is the deposition of, or presence of radioactive substances on surfaces or within solids, liquids, or gases (including the human body), where their presence is unintended or undesirab ...
, as the incident at the Swiss
research reactor in Lucens shows – but yet it resides in INES category 4, together with the
Windscale fire
The Windscale fire of 10 October 1957 was the worst nuclear accident in the United Kingdom's history, and one of the worst in the world, ranked in severity at level 5 out of a possible 7 on the International Nuclear Event Scale. The fire was in ...
of 1957, which has caused significant contamination outside of the facility.
Definition
The definition of the NAMS scale is:
: NAMS = log
10(20 × R)
with R being the radioactivity being released in
terabecquerels, calculated as the equivalent dose of
iodine-131
Iodine-131 (131I, I-131) is an important radioisotope of iodine discovered by Glenn Seaborg and John Livingood in 1938 at the University of California, Berkeley. It has a radioactive decay half-life of about eight days. It is associated with nuc ...
. Furthermore, only the atmospheric release affecting the area ''outside'' the nuclear facility is considered for calculating the NAMS, giving a NAMS score of 0 to all incidents which do not affect the outside. The factor of 20 assures that both the INES and the NAMS scales reside in a similar range, aiding a comparison between accidents. An atmospheric release of any radioactivity will only occur in the INES categories 4 to 7, while NAMS does not have such a limitation.
The NAMS scale still does not take into account the
radioactive contamination
Radioactive contamination, also called radiological pollution, is the deposition of, or presence of radioactive substances on surfaces or within solids, liquids, or gases (including the human body), where their presence is unintended or undesirab ...
of liquids such as an ocean, sea, river or
groundwater pollution
Groundwater pollution (also called groundwater contamination) occurs when pollutants are released to the ground and make their way into groundwater. This type of water pollution can also occur naturally due to the presence of a minor and unwanted ...
in proximity to any
nuclear power plant
A nuclear power plant (NPP) is a thermal power station in which the heat source is a nuclear reactor. As is typical of thermal power stations, heat is used to generate steam that drives a steam turbine connected to a electric generator, generato ...
.
An estimation of its magnitude seems to be related to the problematic definition of a radiological equivalence between different type of involved
isotope
Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbers) ...
s and the variety of
paths by which activity might eventually be ingested,
e.g. eating fish or through the
food chain
A food chain is a linear network of links in a food web starting from producer organisms (such as grass or algae which produce their own food via photosynthesis) and ending at an apex predator species (like grizzly bears or killer whales), det ...
.
See also
*
Nuclear meltdown
A nuclear meltdown (core meltdown, core melt accident, meltdown or partial core melt) is a severe nuclear reactor accident that results in core damage from overheating. The term ''nuclear meltdown'' is not officially defined by the Internation ...
**
Core damage frequency
Core damage frequency (CDF) is a term used in probabilistic risk assessment (PRA) that indicates the likelihood of an accident that would cause severe damage to a nuclear fuel in a nuclear reactor core.
Core damage accidents are considered extreme ...
**
Fuel element failure
A fuel element failure is a rupture in a nuclear reactor's fuel cladding that allows the nuclear fuel or fission products, either in the form of dissolved radioisotopes or hot particles, to enter the reactor coolant or storage water.
The '' ...
**
Loss-of-coolant accident
A loss-of-coolant accident (LOCA) is a mode of failure for a nuclear reactor; if not managed effectively, the results of a LOCA could result in reactor core damage. Each nuclear plant's emergency core cooling system (ECCS) exists specifically t ...
*
Nuclear power
Nuclear power is the use of nuclear reactions to produce electricity. Nuclear power can be obtained from nuclear fission, nuclear decay and nuclear fusion reactions. Presently, the vast majority of electricity from nuclear power is produced b ...
*
Nuclear power debate
The nuclear power debate is a long-running controversy about the risks and benefits of using nuclear reactors to generate electricity for civilian purposes. The debate about nuclear power peaked during the 1970s and 1980s, as more and more reac ...
*
Radioactive contamination
Radioactive contamination, also called radiological pollution, is the deposition of, or presence of radioactive substances on surfaces or within solids, liquids, or gases (including the human body), where their presence is unintended or undesirab ...
*
Radioactive waste
Radioactive waste is a type of hazardous waste that contains radioactive material. Radioactive waste is a result of many activities, including nuclear medicine, nuclear research, nuclear power generation, rare-earth mining, and nuclear weapons r ...
*
Vulnerability of nuclear plants to attack
The vulnerability of nuclear plants to deliberate attack is of concern in the area of nuclear safety and security. Nuclear power plants, civilian research reactors, certain naval fuel facilities, uranium enrichment plants, fuel fabrication plants, ...
*
NRC Emergency Classifications
*
Nuclear and radiation accidents and incidents
A nuclear and radiation accident is defined by the International Atomic Energy Agency (IAEA) as "an event that has led to significant consequences to people, the environment or the facility. Examples include radiation poisoning, lethal effects ...
**
Lists of nuclear disasters and radioactive incidents
These are lists of nuclear disasters and radioactive incidents.
Main lists
* List of attacks on nuclear plants
* List of Chernobyl-related articles
* List of civilian nuclear accidents
* List of civilian radiation accidents
* List of cri ...
**
List of civilian nuclear accidents
This article lists notable civilian accidents involving fissile nuclear material or nuclear reactors. Military accidents are listed at List of military nuclear accidents. Civil radiation accidents not involving fissile material are listed at List ...
**
List of civilian radiation accidents
This article lists notable civilian accidents involving radioactive materials or involving ionizing radiation from artificial sources such as x-ray tubes and particle accelerators. Accidents related to nuclear power that involve fissile materia ...
**
List of military nuclear accidents
This article lists notable military accidents involving nuclear material. Civilian accidents are listed at List of civilian nuclear accidents. For a general discussion of both civilian and military accidents, see nuclear and radiation accidents. Fo ...
***
United States military nuclear incident terminology
The United States Armed Forces uses a number of terms to define the magnitude and extent of nuclear and radiation accidents and incidents in order to reduce the time taken to report the type of incident, thus streamlining the radio communications ...
*
List of nuclear reactors
A ''list'' is any set of items in a row. List or lists may also refer to:
People
* List (surname)
Organizations
* List College, an undergraduate division of the Jewish Theological Seminary of America
* SC Germania List, German rugby union ...
*
Nuclear safety and security
Nuclear safety is defined by the International Atomic Energy Agency (IAEA) as "The achievement of proper operating conditions, prevention of accidents or mitigation of accident consequences, resulting in protection of workers, the public and the ...
*
Criticality accident
A criticality accident is an accidental uncontrolled nuclear fission chain reaction. It is sometimes referred to as a critical excursion, critical power excursion, or divergent chain reaction. Any such event involves the unintended accumulation ...
*
List of hydroelectric power station failures
This is a list of major hydroelectric power station failures due to damage to a hydroelectric power station or its connections. Every generating station trips from time to time due to minor defects and can usually be restarted when the defect h ...
Notes and references
External links
Nuclear Events Web-based System (NEWS) IAEA
International Nuclear Event Scale factsheet IAEA
* International Nuclear Event Scale, User's manual, IAEA, 2008
{{Nuclear technology
*
*
Nuclear safety and security
Nuclear
Nuclear may refer to:
Physics
Relating to the nucleus of the atom:
* Nuclear engineering
*Nuclear physics
*Nuclear power
*Nuclear reactor
*Nuclear weapon
*Nuclear medicine
*Radiation therapy
*Nuclear warfare
Mathematics
*Nuclear space
*Nuclear ...