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.

A representation of the INES levels

The scale is intended to be logarithmic, similar to the moment magnitude scale 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, such as a nuclear accident, is more subject to interpretation. Because of the difficulty of interpreting, the INES level of an incident is assigned well after the incident occurs. Therefore, the scale is not intended to assist in disaster-aid deployment.

Criticism

Deficiencies in the existing INES have emerged through comparisons between the 1986 Chernobyl disaster, which had severe and widespread consequences to humans and the environment, and the 2011 Fukushima Daiichi nuclear accident, 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.[38]

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scale might be preferable to the INES, in the same way that the antiquated Mercalli scale for earthquake magnitudes was superseded by the continuous physically-based Richter scale.[39]

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.[40]

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. 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 in 1986 cannot be measured by that scale. 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 seismologists to describe earthquakes. In that area, magnitude describes the physical energy released by an earthquake, while the intensity 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, as the incident at the Swiss research reactor in Lucens shows – but yet it resides in INES category 5, together with the Windscale fire of 1957, which has caused significant contamination outside of the facility.

Definition

The definition of the NAMS scale is:

NAMS = log10(20 × R)

with R being the radioactivity being released in terabecquerels, calculated as the equivalent dose of iodine-131. 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 does still not take into account the radioactive contamination of liquids such as an ocean, sea, river or groundwater pollution in proximity to any nuclear power plant.
An estimation of its magnitude seems to be related to the problematic definition of a radiological equivalence between different type of involved isotopes and the variety of paths by which activity might eventually be ingested,[41] e.g. eating fish or through the food chain.

See also

Notes and references
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  2. Parfitt, Tom (26 April 2006). "Opinion remains divided over Chernobyl's true toll". The Lancet. pp. 1305–1306. Retrieved 8 May 2019.
  3. Ahlstrom, Dick (2 April 2016). "Chernobyl anniversary: The disputed casualty figures". The Irish Times. Retrieved 8 May 2019.
  4. Mycio, Mary (26 April 2013). "How Many People Have Really Been Killed by Chernobyl? Why estimates differ by tens of thousands of deaths". Slate. Retrieved 8 May 2019.
  5. Ritchie, Hannah (24 July 2017). "What was the death toll from Chernobyl and Fukushima?". Our World in Data. Retrieved 8 May 2019.
  6. Highfield, Roger (21 April 2011). "How many died because of the Chernobyl disaster? We don't really know (Article updated May 7, 2019)". New Scientist. Retrieved 10 May 2019.
  7. "Japan: Nuclear crisis raised to Chernobyl level". BBC News. 12 April 2011. Retrieved 12 April 2011.
  8. "Japan's government downgrades its outlook for growth". BBC News. 13 April 2011. Retrieved 13 April 2011.
  9. Krista Mahr (29 February 2012). "Fukushima Report: Japan Urged Calm While It Mulled Tokyo Evacuation". Time.
  10. "Kyshtym disaster | Causes, Concealment, Revelation, & Facts". Encyclopedia Britannica. Retrieved 11 July 2018.
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  12. Richard Black (18 March 2011). "Fukushima - disaster or distraction?". BBC. Retrieved 7 April 2011.
  13. Spiegelberg-Planer, Rejane. "A Matter of Degree" (PDF). IAEA Bulletin. IAEA. Retrieved 24 May 2016.
  14. Canadian Nuclear Society (1989) The NRX Incident by Peter Jedicke
  15. The Canadian Nuclear FAQ What are the details of the accident at Chalk River's NRX reactor in 1952?
  16. Webb, G A M; Anderson, R W; Gaffney, M J S (2006). "Classification of events with an off-site radiological impact at the Sellafield site between 1950 and 2000, using the International Nuclear Event Scale". Journal of Radiological Protection. IOP. 26 (1): 33–49. doi:10.1088/0952-4746/26/1/002. PMID 16522943.
  17. Сафонов А, Никитин А (2009). Ядерная губа Андреева (PDF).
  18. Lermontov, M.Yu. The death of officer Kalinin S. V. from radiation overdose at Andreev Bay http://andreeva.1gb.ru/story/Kalinin.html The death of officer Kalinin S. V. from radiation overdose at Andreev Bay Check |url= value (help). Missing or empty |title= (help)
  19. Brian, Cowell. "Loss of Off Site Power: An Operator's Perspective, EDF Energy, Nuclear Generation" (PDF). The French Nuclear Energy Company (SFEN). Retrieved 14 May 2019.
  20. Information on Japanese criticality accidents,
  21. "Statement of civil incidents meeting the Ministerial Reportable Criteria (MRC) reported to ONR - Q1 2017". www.onr.org.uk. Retrieved 8 May 2019.
  22. "Sellafield Ltd incident reports and notices". www.gov.co.uk. Retrieved 12 October 2019.
  23. "Statement of civil incidents meeting the Ministerial Reportable Criteria (MRC) reported to ONR - Q1 2018". www.onr.org.uk. Retrieved 14 May 2019.
  24. "Statement of civil incidents meeting the Ministerial Reportable Criteria (MRC) reported to ONR - Q2 2018". www.onr.org.uk. Retrieved 14 May 2019.
  25. (ASN) - 5 April 2012. "ASN has decided to lift its emergency crisis organisation and has temporarily classified the event at the level 1". ASN. Archived from the original on 10 May 2012. Retrieved 6 April 2012.
  26. (AFP) – 10 août 2009. "AFP: Incident "significatif" à la centrale nucléaire de Gravelines, dans le Nord". Retrieved 13 September 2010.
  27. River use banned after French uranium leak | Environment. The Guardian (10 July 2008).
  28. "Sellafield Ltd incident reports and notices". www.gov.co.uk. Retrieved 19 October 2019.
  29. News | Slovenian Nuclear Safety Administration
  30. http://200.0.198.11/comunicados/18_12_2006.pdf%5B%5D (in Spanish)
  31. http://www.jaea.go.jp/02/press2005/p06021301/index.html (in Japanese)
  32. IAEA: "This event is rated as out of scale in accordance with Part I-1.3 of the 1998 Draft INES Users Manual, as it did not involve any possible radiological hazard and did not affect the safety layers."
  33. Archived 21 July 2011 at the Wayback Machine
  34. "NRC: SECY-01-0071 – Expanded NRC Participation in the Use of the International Nuclear Event Scale". US Nuclear Regulatory Commission. 25 April 2001. p. 8. Archived from the original on 27 October 2010. Retrieved 13 March 2011.
  35. "SECY-01-0071-Attachment 5 - INES Reports, 1995–2000". US Nuclear Regulatory Commission. 25 April 2001. p. 1. Archived from the original on 27 October 2010. Retrieved 13 March 2011.
  36. Tornado sighting within protected area | Nuclear power in Europe. Climatesceptics.org. Retrieved on 2013-08-22.
  37. Discovery of suspicious item in plant | Nuclear power in Europe. Climatesceptics.org. Retrieved on 2013-08-22.
  38. Geoff Brumfiel (26 April 2011). "Nuclear agency faces reform calls". Nature.
  39. Spencer Wheatley, Benjamin Sovacool, and Didier Sornette Of Disasters and Dragon Kings: A Statistical Analysis of Nuclear Power Incidents & Accidents, Physics Society, 7 April 2015.
  40. David Smythe (12 December 2011). "An objective nuclear accident magnitude scale for quantification of severe and catastrophic events". Physics Today. doi:10.1063/PT.4.0509.
  41. Smythe, David (12 December 2011). "An objective nuclear accident magnitude scale for quantification of severe and catastrophic events". Physics Today: 13. doi:10.1063/PT.4.0509.
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