Editing Background radiation (section)

==Artificial background radiation==
[[File:Kozloduy Nuclear Power Plant - Background radiation displays.jpg|thumb|Displays showing ambient radiation fields of 0.120–0.130&nbsp;μSv/h (1.05–1.14&nbsp;mSv/a) in a nuclear power plant. This reading includes natural background from cosmic and terrestrial sources.]]

===Atmospheric nuclear testing===
[[Image:US fallout exposure.png|right|thumb|Per capita [[thyroid]] doses in the continental United States resulting from all exposure routes from all atmospheric [[nuclear testing|nuclear tests]] conducted at the [[Nevada Test Site]] from 1951 to 1962.]]

[[File:Radiocarbon bomb spike.svg|thumb|Atmospheric <sup>14</sup>C [[Bomb pulse]], [[New Zealand]]<ref>{{cite journal|url=http://cdiac.esd.ornl.gov/trends/co2/welling.html |title=Atmospheric δ<sup>14</sup>C record from Wellington |access-date=2007-06-11 |journal=Trends: A Compendium of Data on Global Change. Carbon Dioxide Information Analysis Center |year=1994 |url-status=dead |archive-url=https://web.archive.org/web/20140201222225/http://cdiac.esd.ornl.gov/trends/co2/welling.html |archive-date=1 February 2014 }}</ref> and [[Austria]].<ref>{{cite journal| url=http://cdiac.esd.ornl.gov/trends/co2/cent-verm.html| author=Levin, I.| title=δ<sup>14</sup>C record from Vermunt| journal=Trends: A Compendium of Data on Global Change. Carbon Dioxide Information Analysis Center| year=1994| display-authors=etal| access-date=4 January 2016| archive-url=https://web.archive.org/web/20080923105819/http://cdiac.esd.ornl.gov/trends/co2/cent-verm.html| archive-date=23 September 2008| url-status=dead}}</ref> The New Zealand curve is representative for the Southern Hemisphere, the Austrian curve is representative for the Northern Hemisphere. Atmospheric nuclear weapon tests almost doubled the concentration of <sup>14</sup>C in the Northern Hemisphere.<ref>{{cite web | url=http://www1.phys.uu.nl/ams/Radiocarbon.htm | publisher=University of Utrecht | title= Radiocarbon dating | access-date=2008-02-19}}</ref>]]

Frequent above-ground nuclear explosions between the 1940s and 1960s scattered a substantial amount of [[radioactive contamination]]. Some of this contamination is local, rendering the immediate surroundings highly radioactive, while some of it is carried longer distances as [[nuclear fallout]]; some of this material is dispersed worldwide. The increase in background radiation due to these tests peaked in 1963 at about 0.15&nbsp;mSv per year worldwide, or about 7% of average background dose from all sources. The [[Limited Test Ban Treaty]] of 1963 prohibited above-ground tests, thus by the year 2000 the worldwide dose from these tests has decreased to only 0.005&nbsp;mSv per year.<ref name="rrjhjx">{{Cite report |url=https://www.unscear.org/unscear/en/publications/2000_1.html |title=Sources and Effects of Ionizing Radiation - UNSCEAR 2000 Report to the General Assembly, with Scientific Annexes |last=United Nations Scientific Committee on the Effects of Atomic Radiation |date=2000 |language=en |access-date=2022-09-12}}</ref>

This [[global fallout]] has caused an estimated 200,000-460,000 deaths as of 2020.<ref name="s257">{{cite web | last=Adams | first=Lilly | title=Resuming Nuclear Testing a Slap in the Face to Survivors | website=The Equation | date=May 26, 2020 | url=https://blog.ucsusa.org/lilly-adams/resuming-nuclear-testing-a-slap-in-the-face-to-survivors/ | access-date=July 16, 2024}}</ref>

===Occupational exposure===
The [[ICRP|International Commission on Radiological Protection]] recommends limiting occupational radiation exposure to 50&nbsp;mSv (5 rem) per year, and 100&nbsp;mSv (10 rem) in 5 years.<ref name="ICRP103">{{cite book|title=The 2007 Recommendations of the International Commission on Radiological Protection|journal=Annals of the ICRP|year=2007|volume=37|series=ICRP publication 103|issue=2–4|url=http://www.icrp.org/publication.asp?id=ICRP%20Publication%20103|access-date=17 May 2012|isbn=978-0-7020-3048-2|author=ICRP}}</ref>

However, '''background radiation''' for occupational doses includes radiation that is not measured by radiation dose instruments in potential occupational exposure conditions. This includes both offsite "natural background radiation" and any medical radiation doses. This value is not typically measured or known from surveys, such that variations in the total dose to individual workers is not known. This can be a significant confounding factor in assessing radiation exposure effects in a population of workers who may have significantly different natural background and medical radiation doses. This is most significant when the occupational doses are very low.

At an [[IAEA]] conference in 2002, it was recommended that occupational doses below 1–2 mSv per year do not warrant regulatory scrutiny.<ref>{{Cite web |date=30 August 2002 |title=OCCUPATIONAL RADIATION PROTECTION: PROTECTING WORKERS AGAINST EXPOSURE TO IONIZING RADIATION |url=http://www-pub.iaea.org/MTCD/publications/PDF/Pub1145_web.pdf |archive-url=https://web.archive.org/web/20031129163031/http://www-pub.iaea.org/MTCD/publications/PDF/Pub1145_web.pdf |archive-date=2003-11-29 |url-status=live |access-date=21 October 2022 |website=International Atomic Energy Agency}}</ref>

===Nuclear accidents===
[[File:G radiation-level scale 01.png |thumb|right| Radiation level in a range of situations, from normal activities up to the nuclear accidents. Each step up the scale indicates a tenfold increase in radiation level.]]

Under normal circumstances, nuclear reactors release small amounts of radioactive gases, which cause small radiation exposures to the public. Events classified on the [[International Nuclear Event Scale]] as incidents typically do not release any additional radioactive substances into the environment. Large releases of radioactivity from nuclear reactors are extremely rare. To the present day, there were two major ''civilian'' accidents – the [[Chernobyl accident]] and the [[Fukushima I nuclear accidents]] – which caused substantial contamination. The Chernobyl accident was the only one to cause immediate deaths.

Total doses from the Chernobyl accident ranged from 10 to 50 mSv over 20 years for the inhabitants of the affected areas, with most of the dose received in the first years after the disaster, and over 100 mSv for [[Liquidator (Chernobyl)|liquidators]]. There were 28 deaths from [[acute radiation syndrome]].<ref>{{cite web|url=https://www.who.int/ionizing_radiation/chernobyl/backgrounder/en/index.html|author=World Health Organization|title=Health effects of the Chernobyl accident: an overview|date=April 2006|access-date=2013-01-24}}</ref>

Total doses from the Fukushima I accidents were between 1 and 15 mSv for the inhabitants of the affected areas. Thyroid doses for children were below 50 mSv. 167 cleanup workers received doses above 100 mSv, with 6 of them receiving more than 250 mSv (the Japanese exposure limit for emergency response workers).<ref>{{cite journal|title=Fukushima's doses tallied|journal=Nature|volume=485|issue=7399|pages=423–24|author=Geoff Brumfiel|date=2012-05-23|doi=10.1038/485423a|pmid=22622542|bibcode=2012Natur.485..423B|doi-access=free}}</ref>

The average dose from the [[Three Mile Island accident]] was 0.01 mSv.<ref>{{cite web|url=https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/3mile-isle.html|title=Backgrounder on the Three Mile Island Accident|author=U.S. Nuclear Regulatory Commission|date=August 2009|access-date=2013-01-24}}</ref>

'''Non-civilian''': In addition to the civilian accidents described above, several accidents at early nuclear weapons facilities – such as the [[Windscale fire]], the contamination of the [[Techa River]] by the nuclear waste from the [[Mayak]] compound, and the [[Kyshtym disaster]] at the same compound – released substantial radioactivity into the environment. The Windscale fire resulted in thyroid doses of 5–20 mSv for adults and 10–60 mSv for children.<ref>{{cite web|url=http://karws.gso.uri.edu/Marsh/Newsgroups/Wscal-is.htm|title=Radiological Consequences of the 1957 Windscale Fire|date=1997-10-10|access-date=2013-01-24|url-status=dead|archive-url=https://web.archive.org/web/20130517075421/http://karws.gso.uri.edu/Marsh/Newsgroups/Wscal-is.htm|archive-date=17 May 2013}}</ref> The doses from the accidents at Mayak are unknown.

===Nuclear fuel cycle===
The [[Nuclear Regulatory Commission]], the [[United States Environmental Protection Agency]], and other U.S. and international agencies, require that licensees limit radiation exposure to individual members of the public to 1&nbsp;[[sievert|mSv]] (100 m[[roentgen equivalent man|rem]]) per year.

=== Energy sources ===
Per [[United Nations Economic Commission for Europe|UNECE]] life-cycle assessment, nearly all sources of energy result in some level of occupational and public exposure to [[radionuclide]]s as result of their manufacturing or operations. The following table uses man·[[Sievert]]/GW-annum:<ref>{{Cite web|title=Life Cycle Assessment of Electricity Generation Options {{!}} UNECE|url=https://unece.org/sed/documents/2021/10/reports/life-cycle-assessment-electricity-generation-options|access-date=2021-11-08|website=unece.org}}</ref>
{| class="wikitable sortable"
|+
!Source
!Public
!Occupational
|-
|Nuclear power
|0.43
|4.5
|-
|Coal (modern)
|0.7
|11
|-
|Coal (older)
|1.4
|11
|-
|Natural gas
|0.1
|0.02
|-
|Oil
|0.0003
|0.15
|-
|Geothermal
|1–20
|0.05
|-
|Solar power
|
|0.8
|-
|Wind power
|
|0.1
|-
|Biomass
|
|0.01
|}

====Coal burning====
Coal plants emit radiation in the form of radioactive [[fly ash]] which is inhaled and ingested by neighbours, and incorporated into crops. A 1978 paper from [[Oak Ridge National Laboratory]] estimated that coal-fired power plants of that time may contribute a whole-body committed dose of 19&nbsp;μSv/a to their immediate neighbours in a radius of 500 m.<ref>{{cite journal|last1=McBride|first1=J. P.|last2=Moore|first2=R. E. |last3=Witherspoon|first3=J. P.|last4=Blanco|first4=R. E.|title=Radiological impact of airborne effluents of coal and nuclear plants|journal=Science|date=8 Dec 1978|volume=202|issue=4372|pages=1045–50|url= http://www.ornl.gov/info/reports/1977/3445605115087.pdf |access-date=15 November 2012|doi=10.1126/science.202.4372.1045|pmid=17777943|bibcode=1978Sci...202.1045M|s2cid=41057679|archive-url=https://web.archive.org/web/20120927045329/http://www.ornl.gov/info/reports/1977/3445605115087.pdf |archive-date=27 September 2012|url-status=dead}}</ref> The [[United Nations Scientific Committee on the Effects of Atomic Radiation]]'s 1988 report estimated the committed dose 1&nbsp;km away to be 20&nbsp;μSv/a for older plants or 1&nbsp;μSv/a for newer plants with improved fly ash capture, but was unable to confirm these numbers by test.<ref>{{cite book|last=United Nations Scientific Committee on the Effects of Atomic Radiation|title=Sources, Effects and Risks of Ionizing Radiation|series=Radiation Research|volume=120|issue=1|pages=[https://archive.org/details/sourceseffectsri0000unit/page/187 187–88]|year=1988|publisher=United Nations|location=New York|isbn=978-92-1-142143-9|chapter-url=http://www.unscear.org/unscear/en/publications/1988.html|access-date=16 November 2012|chapter=Annex A|bibcode=1989RadR..120..187K|doi=10.2307/3577647|jstor=3577647|s2cid=7316994 |url=https://archive.org/details/sourceseffectsri0000unit/page/187}}</ref> When coal is burned, uranium, thorium and all the uranium daughters accumulated by disintegration&nbsp;– radium, radon, polonium&nbsp;– are released.<ref>{{cite journal|first1=Alex |last1=Gabbard |year=1993 |title= Coal Combustion: Nuclear Resource or Danger? |journal=Oak Ridge National Laboratory Review |volume=26 |issue=3–4 |pages=18–19 |url=http://www.ornl.gov/info/ornlreview/rev26-34/text/colmain.html |url-status=dead |archive-url=https://web.archive.org/web/20070205103749/http://www.ornl.gov/info/ornlreview/rev26-34/text/colmain.html |archive-date=5 February 2007  }}</ref> Radioactive materials previously buried underground in coal deposits are released as fly ash or, if fly ash is captured, may be incorporated into concrete manufactured with fly ash.