Editing Nuclear fallout (section)

== Determining extent of nuclear fallout ==
The [[International Nuclear Event Scale|International Nuclear and Radiological Event Scale]] (INES) is the primary form of categorizing the potential health and environmental effects of a nuclear or radiological event and communicating it to the public.<ref name=":0">{{Cite web|url=https://www.iaea.org/topics/emergency-preparedness-and-response-epr/international-nuclear-radiological-event-scale-ines|title=International Nuclear and Radiological Event Scale (INES)|date=2017-11-22|website=www.iaea.org|access-date=2019-04-19|archive-date=2019-04-19|archive-url=https://web.archive.org/web/20190419165057/https://www.iaea.org/topics/emergency-preparedness-and-response-epr/international-nuclear-radiological-event-scale-ines|url-status=live}}</ref> The scale, which was developed in 1990 by the [[International Atomic Energy Agency]] and the Nuclear Energy Agency of the [[OECD|Organization for Economic Co-operation and Development]], classifies these nuclear accidents based on the potential impact of the fallout:<ref name=":0" /><ref name=":1">{{Cite web|url=https://www.iaea.org/sites/default/files/ines.pdf|title=INES: The International Nuclear and Radiological Event Scale|website=The International Atomic Energy Agency|access-date=2019-04-19|archive-date=2019-06-28|archive-url=https://web.archive.org/web/20190628203331/https://www.iaea.org/sites/default/files/ines.pdf|url-status=live}}</ref>

* Defence-in-Depth: This is the lowest form of nuclear accidents and refers to events that have no direct impact on people or the environment but must be taken note of to improve future safety measures. 
* Radiological Barriers and Control: This category refers to events that have no direct impact on people or the environment and only refer to the damage caused within major facilities.
* People and the Environment: This section of the scale consists of more serious nuclear accidents. Events in this category could potentially cause radiation to spread to people close to the location of the accident. This also includes an unplanned, widespread release of the radioactive material.

The INES scale is composed of seven steps that categorize the nuclear events, ranging from anomalies that must be recorded to improve upon safety measures to serious accidents that require immediate action.

'''Chernobyl'''

The 1986 nuclear reactor explosion at [[Chernobyl disaster|Chernobyl]] was categorized as a Level 7 accident, which is the highest possible ranking on the INES scale, due to widespread environmental and health effects and "external release of a significant fraction of reactor core inventory".<ref name=":1" /> The nuclear accident still stands as the only accident in commercial nuclear power that led to radiation-related deaths.<ref name=":2">{{Cite web|url=http://www.world-nuclear.org/information-library/safety-and-security/safety-of-plants/chernobyl-accident.aspx|title=Chernobyl {{!}} Chernobyl Accident {{!}} Chernobyl Disaster - World Nuclear Association|website=www.world-nuclear.org|access-date=2019-04-19|archive-date=2016-07-16|archive-url=https://web.archive.org/web/20160716045843/http://www.world-nuclear.org/information-library/safety-and-security/safety-of-plants/chernobyl-accident.aspx|url-status=live}}</ref> The steam explosion and fires released approximately 5200 PBq, or at least 5 percent of the reactor core, into the atmosphere.<ref name=":2" /> The explosion itself resulted in the deaths of two plant workers, while 28 people died over the weeks that followed of severe radiation poisoning.<ref name=":2" /> Furthermore, young children and adolescents in the areas most contaminated by the radiation exposure showed an increase in the risk for [[thyroid cancer]], although the [[United Nations Scientific Committee on the Effects of Atomic Radiation]] stated that "there is no evidence of a major public health impact" apart from that.<ref name=":2" /><ref>{{Cite web|url=https://www.who.int/ionizing_radiation/chernobyl/backgrounder/en/|title=WHO {{!}} Health effects of the Chernobyl accident: an overview|website=WHO|access-date=2019-04-19|archive-date=2019-04-20|archive-url=https://web.archive.org/web/20190420143912/https://www.who.int/ionizing_radiation/chernobyl/backgrounder/en/|url-status=live}}</ref> The nuclear accident also took a heavy toll on the environment, including contamination in urban environments caused by the deposition of radionuclides and the contamination of "different crop types, in particular, green leafy vegetables ... depending on the deposition levels, and time of the growing season".<ref>{{Cite web|url=https://www-ns.iaea.org/downloads/rw/meetings/environ-consequences-report-wm-08.05.pdf|title=Environmental Consequences of the Chernobyl Accident and Their Remediation: Twenty Years of Experience|date=August 2005|website=The International Atomic Energy Agency|access-date=2019-04-19|archive-date=2019-02-03|archive-url=https://web.archive.org/web/20190203205859/http://www-ns.iaea.org/downloads/rw/meetings/environ-consequences-report-wm-08.05.pdf|url-status=live}}</ref>

'''Three Mile Island'''

The nuclear meltdown at [[Three Mile Island accident|Three Mile Island]] in 1979 was categorized as a Level 5 accident on the INES scale because of the "severe damage to the reactor core" and the radiation leak caused by the incident.<ref name=":1" /> Three Mile Island was the most serious accident in the history of American commercial nuclear power plants, yet the effects were different from those of the Chernobyl accident.<ref name=":3">{{Cite web|url=https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/3mile-isle.html|title=NRC: Backgrounder on the Three Mile Island Accident|website=www.nrc.gov|access-date=2019-04-19|archive-date=2021-11-15|archive-url=https://web.archive.org/web/20211115101945/https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/3mile-isle.html|url-status=live}}</ref> A study done by the [[Nuclear Regulatory Commission]] following the incident reveals that the nearly 2 million people surrounding the Three Mile Island plant "are estimated to have received an average radiation dose of only 1 millirem above the usual background dose".<ref name=":3" /> Furthermore, unlike those affected by radiation in the Chernobyl accident, the development of thyroid cancer in the people around Three Mile Island was "less aggressive and less advanced".<ref>{{Cite journal|last1=Goyal|first1=Neerav|last2=Camacho|first2=Fabian|last3=Mangano|first3=Joseph|last4=Goldenberg|first4=David|date=March 22, 2012|title=Thyroid cancer characteristics in the population surrounding Three Mile Island|journal=The Laryngoscope|volume=122|issue=6|pages=1415–21|doi=10.1002/lary.23314|pmid=22565486|s2cid=5132110}}</ref>

'''Fukushima'''
[[File:Fukushima- Panache-25-mars.svg|thumb|250px|Calculated [[caesium-137]] concentration in the air, 25 March 2011]]
Like the Three Mile Island incident, the incident at [[Fukushima Daiichi nuclear disaster|Fukushima]] was initially categorized as a Level 5 accident on the INES scale after a tsunami disabled the power supply and cooling of three reactors, which then suffered significant melting in the days that followed.<ref name=":4">{{Cite web|url=http://www.world-nuclear.org/information-library/safety-and-security/safety-of-plants/fukushima-accident.aspx|title=Fukushima Daiichi Accident - World Nuclear Association|website=www.world-nuclear.org|access-date=2019-04-19|archive-date=2019-04-17|archive-url=https://web.archive.org/web/20190417103109/http://www.world-nuclear.org/information-library/safety-and-security/safety-of-plants/fukushima-accident.aspx|url-status=live}}</ref> However, after combining the events at the three reactors rather than assessing them individually, the accident was upgraded to an INES Level 7.<ref>{{Cite web|url=https://www.iaea.org/newscenter/news/fukushima-nuclear-accident-update-log-15|title=Fukushima Nuclear Accident Update Log|date=2011-04-12|website=www.iaea.org|access-date=2019-04-19|archive-date=2019-04-19|archive-url=https://web.archive.org/web/20190419212715/https://www.iaea.org/newscenter/news/fukushima-nuclear-accident-update-log-15|url-status=live}}</ref> The radiation exposure from the incident caused a recommended evacuation for inhabitants up to 30&nbsp;km away from the plant.<ref name=":4" /> However, it was also hard to track such exposure because 23 out of the 24 radioactive monitoring stations were also disabled by the tsunami.<ref name=":4" /> Removing contaminated water, both in the plant itself and run-off water that spread into the sea and nearby areas, became a huge challenge for the Japanese government and plant workers. During the containment period following the accident, thousands of cubic meters of slightly contaminated water were released in the sea to free up storage for more contaminated water in the reactor and turbine buildings.<ref name=":4" /> However, the fallout from the Fukushima accident had a minimal impact on the surrounding population. According to the [[Institut de radioprotection et de sûreté nucléaire|Institut de Radioprotection et de Sûreté Nucléaire]], over 62 percent of assessed residents within the Fukushima prefecture received external doses of less than 1 mSv in the four months following the accident.<ref name=":5">{{Cite web|url=https://www.irsn.fr/EN/publications/thematic-safety/fukushima/fukushima-2016/Pages/Fukushima-in-2016-Health-impact.aspx|title=Health impact in 2016 of the Fukushima Daiichi accident|website=www.irsn.fr|access-date=2019-04-19|archive-date=2019-04-19|archive-url=https://web.archive.org/web/20190419212656/https://www.irsn.fr/EN/publications/thematic-safety/fukushima/fukushima-2016/Pages/Fukushima-in-2016-Health-impact.aspx|url-status=live}}</ref> In addition, comparing screening campaigns for children inside the Fukushima prefecture and in the rest of the country revealed no significant difference in the risk of thyroid cancer.<ref name=":5" />