Editing Depleted uranium (section)

==Production==
Most depleted uranium arises as a [[by-product]] of the production of [[enriched uranium]] for use as fuel in [[nuclear reactor]]s and in the manufacture of [[nuclear weapon]]s. Enrichment processes generate uranium with a higher-than-natural concentration of lower-[[atomic mass number|mass-number]] uranium isotopes (in particular <sup>235</sup>U, which is the uranium isotope supporting the [[Nuclear fission|fission]] [[chain reaction]]) with the bulk of the feed ending up as depleted uranium.

[[Natural uranium]] metal contains about {{percentage|0.71|100|2}} <sup>235</sup>U, {{percentage|99.28|100|2}} <sup>238</sup>U, and about {{percentage|0.0054|100|4}} <sup>234</sup>U. The production of enriched uranium using [[isotope separation]] creates ''depleted uranium'' containing only 0.2% to 0.4% <sup>235</sup>U. Because natural uranium begins with such a low percentage of <sup>235</sup>U, enrichment produces large quantities of depleted uranium. For example, producing {{convert|1|kg}} of {{percentage|5|100}} enriched uranium requires {{convert|11.8|kg}} of natural uranium, and leaves about {{convert|10.8|kg}} of depleted uranium having only {{percentage|0.3|100|1}} <sup>235</sup>U.

Depleted uranium is further produced by recycling [[spent nuclear fuel]],<ref>{{Cite web |date=2003-01-24 |title=Depleted Uranium |url=http://www.who.int/mediacentre/factsheets/fs257/en/ |access-date=2024-06-04 |series=WHO Fact sheet N°257, Revised |archive-date=24 January 2003 |archive-url=https://web.archive.org/web/20030124030930/http://www.who.int/mediacentre/factsheets/fs257/en/ |url-status=bot: unknown }}</ref> in which case it contains traces of [[neptunium]] and [[plutonium]].<ref>[http://www.nukewatchinfo.org/Quarterly/2007spring/07sprp11.pdf Plutonium in DU Weapons, a Chronology] {{Webarchive|url=https://web.archive.org/web/20130510011456/http://www.nukewatchinfo.org/Quarterly/2007spring/07sprp11.pdf|date=10 May 2013}} Dr. [[Michael Repacholi]], WHO.</ref> These quantities are so small that they are not considered to be of serious radiological significance by the [[ECRR|European Committee on Radiation Risk]].<ref>{{cite web |author=Busby, Chris |date=2010 |title=Uranium and Health: The Health Effects of Exposure to Uranium and Uranium Weapons Fallout |url=http://www.euradcom.org/publications/ecrruraniumrept.pdf |url-status=dead |archive-url=https://web.archive.org/web/20111104145155/http://www.euradcom.org/publications/ecrruraniumrept.pdf |archive-date=4 November 2011 |publisher=The European Committee on Radiation Risk}} Documents of the ECRR 2010 No. 2, Brussels, Belgium, 2010.</ref> DU from [[nuclear reprocessing]] has different isotopic ratios from enrichment-by-product DU, from which it can be distinguished by the presence of [[Uranium-236|<sup>236</sup>U]].<ref>{{cite press release |url=https://www.un.org/News/Press/docs/2001/unep81.doc.htm |title=UN Environment Programme Confirms Uranium 236 found in depleted uranium penetrators |date=16 January 2001 |id=UNEP/81 |publisher=United Nations |archive-url=https://web.archive.org/web/20010717004828/https://www.un.org/News/Press/docs/2001/unep81.doc.htm |archive-date=17 July 2001 |access-date=28 April 2020}}</ref>

The only known natural source of uranium with a {{chem|235|U}} content significantly different from 0.71% is found in the [[natural nuclear fission reactor]] at [[Oklo|Oklo, Gabon]]. It can be "fingerprinted" as different in origin from manmade depleted uranium by the {{chem|234|U}} content, which is 55 [[parts per million|ppm]] in uranium from the [[Oklo Mine]] as well as all other natural sources, but will be lower in depleted uranium in accordance with the degree of depletion.