Editing Americium (section)

==Occurrence==
{{See also|Nuclear reprocessing}}
[[File:Ivy Mike - mushroom cloud.jpg|thumb|Americium was detected in the fallout from the ''[[Ivy Mike]]'' nuclear test.]]
The longest-lived and most common isotopes of americium, <sup>241</sup>Am and <sup>243</sup>Am, have half-lives of 432.2 and 7,370 years, respectively. Therefore, any [[Primordial nuclide|primordial]] americium (americium that was present on Earth during its formation) should have decayed by now. Trace amounts of americium probably occur naturally in uranium minerals as a result of neutron capture and beta decay (<sup>238</sup>U → <sup>239</sup>Pu → <sup>240</sup>Pu → <sup>241</sup>Am), though the quantities would be tiny and this has not been confirmed.<ref>{{Cite web|url=https://www.livescience.com/39874-facts-about-americium.html|title=Facts About Americium|last=Earth|first=Rachel Ross 2017-05-23T02:31:00Z Planet|website=livescience.com|date=23 May 2017|language=en|access-date=2019-08-10}}</ref><ref>{{Cite web|url=http://www.rsc.org/periodic-table/element/95/americium|title=Americium - Element information, properties and uses {{!}} Periodic Table|website=www.rsc.org|access-date=2019-08-10}}</ref><ref name=ThorntonBurdette>{{cite journal |last1=Thornton |first1=Brett F. |last2=Burdette |first2=Shawn C. |date=2019 |title=Neutron stardust and the elements of Earth |url=https://www.nature.com/articles/s41557-018-0190-9 |journal=Nature Chemistry |volume=11 |issue=1 |pages=4–10 |doi=10.1038/s41557-018-0190-9 |pmid=30552435 |bibcode=2019NatCh..11....4T |s2cid=54632815 |access-date=19 February 2022}}</ref> Extraterrestrial long-lived <sup>247</sup>Cm is probably also deposited on Earth and has <sup>243</sup>Am as one of its intermediate decay products, but again this has not been confirmed.<ref name=ThorntonBurdette/>

Existing americium is concentrated in the areas used for the atmospheric [[nuclear weapons tests]] conducted between 1945 and 1980, as well as at the sites of nuclear incidents, such as the [[Chernobyl disaster]]. For example, the analysis of the debris at the testing site of the first U.S. [[hydrogen bomb]], [[Ivy Mike]], (1 November 1952, [[Enewetak Atoll]]), revealed high concentrations of various actinides including americium; but due to military secrecy, this result was not published until later, in 1956.<ref>{{cite journal|last1=Fields|first1=P. R.|last2=Studier|first2=M. H.|last3=Diamond|first3=H.|last4=Mech|first4=J. F.|last5=Inghram|first5=M. G.|last6=Pyle|first6=G. L.|last7=Stevens|first7=C. M.|last8=Fried|first8=S.|last9=Manning|first9=W. M.|last10=Ghiorso|first10=A.|last11=Thompson|first11=S. G.|last12=Higgins|first12=G. H.|last13=Seaborg|first13=G. T.|display-authors=3|title=Transplutonium Elements in Thermonuclear Test Debris|date=1956|journal=Physical Review|volume=102|issue=1|pages=180–182|doi=10.1103/PhysRev.102.180|bibcode=1956PhRv..102..180F}}</ref> [[Trinitite]], the glassy residue left on the desert floor near [[Alamogordo, New Mexico]], after the [[plutonium]]-based [[Trinity test|Trinity]] [[nuclear testing|nuclear bomb test]] on 16 July 1945, contains traces of americium-241. Elevated levels of americium were also detected at the [[1968 Thule Air Base B-52 crash|crash site]] of a US [[Boeing B-52]] bomber aircraft, which carried four hydrogen bombs, in 1968 in [[Greenland]].<ref>{{cite book|author=Eriksson, Mats |title=On Weapons Plutonium in the Arctic Environment |publisher=[[Lund University]] |date=April 2002 |location=Risø National Laboratory, Roskilde, Denmark |access-date=15 November 2008 |url=http://www.risoe.dk/rispubl/NUK/nukpdf/ris-r-1321.pdf |page=28 |archive-url=https://web.archive.org/web/20081218233551/http://www.risoe.dk/rispubl/NUK/nukpdf/ris-r-1321.pdf |archive-date=18 December 2008 |url-status=dead }}</ref>

In other regions, the average radioactivity of surface soil due to residual americium is only about 0.01&nbsp;[[picocuries]] per gram (0.37&nbsp;[[mBq]]/g). Atmospheric americium compounds are poorly soluble in common solvents and mostly adhere to soil particles. Soil analysis revealed about 1,900 times higher concentration of americium inside sandy soil particles than in the water present in the soil pores; an even higher ratio was measured in [[loam]] soils.<ref name="am">[http://www.ead.anl.gov/pub/doc/americium.pdf Human Health Fact Sheet on Americium] {{webarchive|url=https://web.archive.org/web/20110716164652/http://www.ead.anl.gov/pub/doc/americium.pdf |date=16 July 2011 }}, Los Alamos National Laboratory, Retrieved 28 November 2010</ref>

Americium is produced mostly artificially in small quantities, for research purposes. A tonne of spent nuclear fuel contains about 100&nbsp;grams of various americium isotopes, mostly <sup>241</sup>Am and <sup>243</sup>Am.<ref>Hoffmann, Klaus ''Kann man Gold machen? Gauner, Gaukler und Gelehrte. Aus der Geschichte der chemischen Elemente'' (Can you make gold? Crooks, clowns, and scholars. From the history of the chemical elements), Urania-Verlag, Leipzig, Jena, Berlin 1979, no ISBN, p. 233</ref> Their prolonged radioactivity is undesirable for the disposal, and therefore americium, together with other long-lived actinides, must be neutralized. The associated procedure may involve several steps, where americium is first separated and then converted by neutron bombardment in special reactors to short-lived nuclides. This procedure is well known as [[nuclear transmutation]], but it is still being developed for americium.<ref>Baetslé, L. [http://www.ictp.trieste.it/~pub_off/lectures/lns012/Baetsle.pdf Application of Partitioning/Transmutation of Radioactive Materials in Radioactive Waste Management] {{webarchive|url=https://web.archive.org/web/20050426092418/http://www.ictp.trieste.it/~pub_off/lectures/lns012/Baetsle.pdf |date=26 April 2005 }}, Nuclear Research Centre of Belgium Sck/Cen, Mol, Belgium, September 2001, Retrieved 28 November 2010</ref><ref>Fioni, Gabriele; Cribier, Michel and Marie, Frédéric [http://www.cea.fr/var/cea/storage/static/gb/library/Clefs46/pagesg/clefs46_30.html Can the minor actinide, americium-241, be transmuted by thermal neutrons?] {{webarchive|url=https://web.archive.org/web/20071111175005/http://www.cea.fr/var/cea/storage/static/gb/library/Clefs46/pagesg/clefs46_30.html |date=11 November 2007 }}, Department of Astrophysics, CEA/Saclay, Retrieved 28 November 2010</ref> The [[transuranic element]]s from americium to [[fermium]] occurred naturally in the [[natural nuclear fission reactor]] at [[Oklo]], but no longer do so.<ref name="emsley">{{cite book|last=Emsley|first=John|title=Nature's Building Blocks: An A-Z Guide to the Elements|edition=New|date=2011|publisher=Oxford University Press|location=New York, NY|isbn=978-0-19-960563-7}}</ref>

Americium is also one of the elements that have theoretically been detected in [[Przybylski's Star]].<ref name=gopka08>{{cite journal |last1=Gopka |first1=V. F. |last2=Yushchenko |first2=A. V. |last3=Yushchenko |first3=V. A. |last4=Panov |first4=I. V. |last5=Kim |first5=Ch. |title=Identification of absorption lines of short half-life actinides in the spectrum of Przybylski's star (HD 101065) |journal=Kinematics and Physics of Celestial Bodies |date=15 May 2008 |volume=24 |issue=2 |pages=89–98 |doi=10.3103/S0884591308020049 |bibcode = 2008KPCB...24...89G |s2cid=120526363 }}</ref>