Editing Technetium (section)

===Fission product for commercial use===
The [[Metastability|metastable]] isotope technetium-99m is continuously produced as a [[fission product]] from the fission of uranium or [[plutonium]] in [[nuclear reactor]]s:

<chem display="block"> ^{238}_{92}U ->[\ce{sf}] ^{137}_{53}I + ^{99}_{39}Y + 2^{1}_{0}n</chem>
<chem display="block"> ^{99}_{39}Y ->[\beta^-][1.47\,\ce{s}] ^{99}_{40}Zr ->[\beta^-][2.1\,\ce{s}] ^{99}_{41}Nb ->[\beta^-][15.0\,\ce{s}] ^{99}_{42}Mo ->[\beta^-][65.94\,\ce{h}] ^{99}_{43}Tc ->[\beta^-][211,100\,\ce{y}] ^{99}_{44}Ru</chem>

Because used fuel is allowed to stand for several years before reprocessing, all molybdenum-99 and technetium-99m is decayed by the time that the fission products are separated from the major [[actinide]]s in conventional [[nuclear reprocessing]]. The liquid left after plutonium–uranium extraction ([[PUREX]]) contains a high concentration of technetium as {{chem|TcO|4|-}} but almost all of this is technetium-99, not technetium-99m.{{sfn|Schwochau|2000|p=39}}

The vast majority of the technetium-99m used in medical work is produced by irradiating dedicated [[enriched uranium#Highly enriched uranium (HEU)|highly enriched uranium]] targets in a reactor, extracting molybdenum-99 from the targets in reprocessing facilities,<ref name="nuclmed">{{cite journal|last=Moore |first=P. W.|title=Technetium-99 in generator systems|journal=Journal of Nuclear Medicine |date=April 1984 |volume=25 |issue=4|pages=499–502 |pmid=6100549|url=http://jnm.snmjournals.org/content/25/4/499.full.pdf |access-date=2012-05-11}}</ref> and recovering at the diagnostic center the technetium-99m produced upon decay of molybdenum-99.<ref>{{cite patent|country=US |number=3799883|title=Silver coated charcoal step |invent1=Hirofumi Arino|assign1= Union Carbide Corporation|gdate=March 26, 1974}}</ref><ref>{{cite book| title = Medical Isotope Production Without Highly Enriched Uranium| author=Committee on Medical Isotope Production Without Highly Enriched Uranium| publisher=National Academies Press|page=vii |isbn=978-0-309-13040-0|date=2009}}</ref> Molybdenum-99 in the form of molybdate {{chem|MoO|4|2-}} is [[adsorption|adsorbed]] onto acid alumina ({{chem|Al|2|O|3}}) in a [[radiation shielding|shielded]] [[column chromatography|column chromatograph]] inside a [[technetium-99m generator]] ("technetium cow", also occasionally called a "molybdenum cow"). Molybdenum-99 has a half-life of 67&nbsp;hours, so short-lived technetium-99m (half-life: 6&nbsp;hours), which results from its decay, is being constantly produced.<ref name="blocks" /> The soluble [[pertechnetate]] {{chem|TcO|4|-}} can then be chemically extracted by [[elution]] using a [[saline solution]]. A drawback of this process is that it requires targets containing uranium-235, which are subject to the security precautions of fissile materials.<ref>{{cite news |last=Lützenkirchen |first=K.-R. |title=Nuclear forensics sleuths trace the origin of trafficked material |url=http://arq.lanl.gov/source/orgs/nmt/nmtdo/AQarchive/4thQuarter07/page1.shtml |publisher=Los Alamos National Laboratory |access-date=2009-11-11 |url-status=dead |archive-url=https://web.archive.org/web/20130216114404/http://arq.lanl.gov/source/orgs/nmt/nmtdo/AQarchive/4thQuarter07/page1.shtml |archive-date=2013-02-16}}</ref><ref>{{cite conference|last1=Snelgrove|first1=J. L.|first2=G. L. |last2=Hofman |url=http://www.rertr.anl.gov/MO99/JLS.pdf|title=Development and Processing of LEU Targets for Mo-99 Production| date=1995| access-date=2009-05-05 |work=ANL.gov |conference=1995 International Meeting on Reduced Enrichment for Research and Test Reactors, September 18–21, 1994, Paris, France}}</ref>
[[File:First technetium-99m generator - 1958.jpg|thumb|upright|The first [[technetium-99m generator]], unshielded, 1958. A Tc-99m [[pertechnetate]] solution is being eluted from Mo-99 [[molybdate]] bound to a chromatographic substrate]]
Almost two-thirds of the world's supply comes from two reactors; the [[National Research Universal Reactor]] at [[Chalk River Laboratories]] in Ontario, Canada, and the [[Petten nuclear reactor|High Flux Reactor]] at [[Nuclear Research and Consultancy Group]] in Petten, Netherlands. All major reactors that produce technetium-99m were built in the 1960s and are close to the [[End-of-life (product)|end of life]]. The two new Canadian [[Multipurpose Applied Physics Lattice Experiment]] reactors planned and built to produce 200% of the demand of technetium-99m relieved all other producers from building their own reactors. With the cancellation of the already tested reactors in 2008, the future supply of technetium-99m became problematic.<ref>{{cite journal | last1 = Thomas | first1 = Gregory S. | last2 = Maddahi | first2 = Jamshid | title = The technetium shortage | journal = [[Journal of Nuclear Cardiology]] | volume = 17 | pages = 993–8 | date = 2010 | doi = 10.1007/s12350-010-9281-8 | issue = 6 | pmid=20717761| s2cid = 2397919 }}</ref>