Editing Thorium (section)

===Nuclear weapons===
When gram quantities of [[plutonium]] were first produced in the [[Manhattan Project]], it was discovered that a minor isotope ([[plutonium-240|<sup>240</sup>Pu]]) underwent significant [[spontaneous fission]], which brought into question the viability of a plutonium-fuelled [[Gun-type fission weapon|gun-type nuclear weapon]]. While the [[Project Y|Los Alamos]] team began work on the [[Nuclear weapon design#Implosion-type weapon|implosion-type weapon]] to circumvent this issue, the [[Metallurgical Laboratory|Chicago team]] discussed reactor design solutions. [[Eugene Wigner]] proposed to use the <sup>240</sup>Pu-contaminated plutonium to drive the conversion of thorium into <sup>233</sup>U in a special converter reactor. It was hypothesized that the <sup>233</sup>U would then be usable in a gun-type weapon, though concerns about contamination from <sup>232</sup>U were voiced. Progress on the implosion weapon was sufficient, and this converter was not developed further, but the design had enormous influence on the development of nuclear energy. It was the first detailed description of a highly enriched water-cooled, water-moderated reactor similar to future naval and commercial power reactors.<ref name="First Nuclear Era">{{cite book |last=Weinberg |first=Alvin |author-link=Alvin Weinberg |year=1994 |title=The First Nuclear Era: The life and times of a technological fixer |pages=36–38 |location=New York |publisher=AIP Press |isbn=978-1-56396-358-2}}</ref>

During the [[Cold War]] the United States explored the possibility of using <sup>232</sup>Th as a source of <sup>233</sup>U to be used in a [[nuclear bomb]]; they fired [[Operation Teapot#MET|a test bomb]] in 1955.<ref name="World Nuclear Association Thorium">{{cite web |title=Thorium |publisher=[[World Nuclear Association]] |year=2017 |url=http://www.world-nuclear.org/information-library/current-and-future-generation/thorium.aspx |access-date=21 June 2017 |archive-date=8 May 2017 |archive-url=https://web.archive.org/web/20170508215033/http://www.world-nuclear.org/information-library/current-and-future-generation/thorium.aspx |url-status=live }}</ref> They concluded that a <sup>233</sup>U-fired bomb would be a very potent weapon, but it bore few sustainable "technical advantages" over the contemporary uranium–plutonium bombs,<ref>{{cite report |last=Woods |first=W.K. |date=1966 |title=LRL Interest in U-233 |publisher=[[Battelle Memorial Institute]] |doi=10.2172/79078 |osti=79078 |language=en |url=https://digital.library.unt.edu/ark:/67531/metadc720752/m2/1/high_res_d/79078.pdf |archive-date=10 September 2023 |access-date=24 August 2019 |archive-url=https://web.archive.org/web/20230910145607/https://digital.library.unt.edu/ark:/67531/metadc720752/m2/1/high_res_d/79078.pdf |url-status=live }}</ref> especially since <sup>233</sup>U is difficult to produce in isotopically pure form.<ref name="World Nuclear Association Thorium" />

Thorium metal was used in the [[hohlraum|radiation case]] of at least one nuclear weapon design deployed by the United States (the [[W71]]).<ref>{{cite web |title=Classification Bulletin WNP-118 |publisher=U.S. Department of Energy |date=12 March 2008 |url=https://www.osti.gov/opennet/servlets/purl/1052069/1052069.pdf |access-date=13 September 2019 |archive-date=3 February 2017 |archive-url=https://web.archive.org/web/20170203132623/https://www.osti.gov/opennet/servlets/purl/1052069/1052069.pdf |url-status=live }}</ref>