Editing Nuclear reprocessing (section)

====Modifications of PUREX====
Many of these concepts, particularly those that separate the [[minor actinides]] once U and Pu have been extracted, are summarised in the [[advanced reprocessing of spent nuclear fuel]]. 

=====UREX=====
The PUREX process can be modified to make a '''UREX''' ('''UR'''anium '''EX'''traction) process which could be used to save space inside high level [[nuclear waste]] disposal sites, such as the [[Yucca Mountain nuclear waste repository]], by removing the uranium which makes up the vast majority of the mass and volume of used fuel and recycling it as [[reprocessed uranium]].

The UREX process is a PUREX process which has been modified to prevent the plutonium from being extracted. This can be done by adding a plutonium [[reductant]] before the first metal extraction step. In the UREX process, ~99.9% of the uranium and >95% of [[technetium]] are separated from each other and the other fission products and [[actinide]]s. The key is the addition of [[acetohydroxamic acid]] (AHA) to the extraction and scrub sections of the process. The addition of AHA greatly diminishes the extractability of plutonium and [[neptunium]], providing somewhat greater proliferation resistance than with the plutonium extraction stage of the PUREX process.{{citation needed|date=December 2012}}

=====TRUEX=====
Adding a second extraction agent, octyl(phenyl)-N, N-dibutyl carbamoylmethyl phosphine oxide (CMPO) in combination with tributylphosphate, (TBP), the PUREX process can be turned into the '''TRUEX''' ('''TR'''ans'''U'''ranic '''EX'''traction) process. TRUEX was invented in the US by [[Argonne National Laboratory]] and is designed to remove the transuranic metals (Am/Cm) from waste. The idea is that by lowering the [[Alpha decay#Toxicity|alpha activity]] of the waste, the majority of the waste can then be disposed of with greater ease. In common with PUREX this process operates by a [[solvation]] mechanism.

=====DIAMEX=====
As an alternative to TRUEX, an extraction process using a malondiamide has been devised. The DIAMEX ('''DIAM'''ide '''EX'''traction) process has the advantage of avoiding the formation of organic waste which contains elements other than [[carbon]], [[hydrogen]], [[nitrogen]], and [[oxygen]]. Such an organic waste can be burned without the formation of acidic gases which could contribute to [[acid rain]] (although the acidic gases could be recovered by a scrubber). The DIAMEX process is being worked on in Europe by the French [[Commissariat à l'énergie atomique|CEA]]. The process is sufficiently mature that an industrial plant could be constructed with the existing knowledge of the process.<ref>{{cite web|title=Nuclear Energy: Fuel of the Future? |url=http://blogs.princeton.edu/chm333/f2006/nuclear/05_reprocessing/possible_methods_of_reprocessing/ |publisher=Princeton University |access-date=6 April 2013 |url-status=dead |archive-url=https://web.archive.org/web/20121001033741/http://blogs.princeton.edu/chm333/f2006/nuclear/05_reprocessing/possible_methods_of_reprocessing/ |archive-date=1 October 2012 }}</ref> In common with PUREX this process operates by a solvation mechanism.

=====SANEX=====
'''S'''elective '''A'''cti'''N'''ide '''EX'''traction. As part of the management of minor actinides it has been proposed that the [[lanthanide]]s and trivalent minor [[actinide]]s should be removed from the PUREX [[raffinate]] by a process such as DIAMEX or TRUEX. To allow the actinides such as americium to be either reused in industrial sources or used as fuel, the lanthanides must be removed. The lanthanides have large neutron cross sections and hence they would poison a neutron driven nuclear reaction. To date the extraction system for the SANEX process has not been defined, but currently several different research groups are working towards a process. For instance the French [[Commissariat à l'énergie atomique|CEA]] is working on a [[bis-triazinyl pyridine]] (BTP) based process.<ref><!-- These preprints need to be replaced with appropriate peer-reviewed articles. -->C. Hill, D. Guillaneux, X. Hérès, N. Boubals and L. Ramain [http://www-atalante2004.cea.fr/home/liblocal/docs/atalante2000/P3-26.pdf SANEX-BTP PROCESS DEVELOPMENT STUDIES] {{webarchive|url=https://web.archive.org/web/20121115151847/http://www-atalante2004.cea.fr/home/liblocal/docs/atalante2000/P3-26.pdf|date=15 November 2012}}</ref><ref>C. Hill, L. Berthon, P. Bros, J-P. Dancausse and D. Guillaneux [http://www.nea.fr/html/pt/docs/iem/jeju02/session2/Session%20II-19.pdf SANEX-BTP PROCESS DEVELOPMENT STUDIES] {{Webarchive|url=https://web.archive.org/web/20090905052047/http://www.nea.fr/html/pt/docs/iem/jeju02/session2/Session%20II-19.pdf |date=5 September 2009 }}. Commissariat à l'Énergie Atomique</ref><ref>Béatrice Rat, Xavier Hérès [http://www-atalante2004.cea.fr/home/liblocal/docs/atalante2000/P3-24.pdf Modelling and achievement of a SANEX process flowsheet for trivalent actinides/lanthanides separation using BTP extractant (bis-1,2,4-triazinyl-pyridine).] {{webarchive|url=https://web.archive.org/web/20051016074429/http://www-atalante2004.cea.fr/home/liblocal/docs/atalante2000/P3-24.pdf |date=16 October 2005 }}</ref>
Other systems such as the dithiophosphinic acids are being worked on by some other workers.

=====UNEX=====
The '''''UN'''iversal'' '''EX'''traction process was developed in Russia and the [[Czech Republic]]; it is designed to completely remove the most troublesome [[radioisotopes]] (Sr, Cs and [[minor actinides]]) from the raffinate remaining after the extraction of uranium and plutonium from used [[nuclear fuel]].<ref>{{cite web |url=http://www.usembassy.it/file2001_12/alia/a1121910.htm |archive-url=https://web.archive.org/web/20140728001906/http://www.usembassy.it/file2001_12/alia/a1121910.htm |archive-date=28 July 2014 | title=U.S.-Russia Team Makes Treating Nuclear Waste Easier |publisher=U.S. embassy press release(?) | date=19 December 2001 |access-date=14 June 2007}}</ref><ref>{{cite web |url=http://www.osti.gov/bridge/product.biblio.jsp?osti_id=765723 |title=INTEC High-Level Waste Studies Universal Solvent Extraction Feasibility Study |publisher=INEEL Technical report |date=1 September 2001 |author=J. Banaee |display-authors=etal |access-date=28 January 2006 |archive-date=13 May 2013 |archive-url=https://web.archive.org/web/20130513122509/http://www.osti.gov/bridge/product.biblio.jsp?osti_id=765723 |url-status=live }}</ref> The chemistry is based upon the interaction of [[caesium]] and [[strontium]] with [[polyethylene glycol]]<ref>{{cite journal|doi=10.1081/SEI-100001371|title=The Universal Solvent Extraction (Unex) Process. Ii. Flowsheet Development and Demonstration of the Unex Process for the Separation of Cesium, Strontium, and Actinides from Actual Acidic Radioactive Waste|year=2001|last1=Law|first1=Jack D.|last2=Herbst|first2=R. Scott|last3=Todd|first3=Terry A.|last4=Romanovskiy|first4=Valeriy N.|last5=Babain|first5=Vasily A.|last6=Esimantovskiy|first6=Vyatcheslav M.|last7=Smirnov|first7=Igor V.|last8=Zaitsev|first8=Boris N.|journal=Solvent Extraction and Ion Exchange|volume=19|page=23|s2cid=98103735}}</ref><ref>{{cite journal|doi=10.1081/SEI-100001370|title=The Universal Solvent Extraction (Unex) Process. I. Development of the Unex Process Solvent for the Separation of Cesium, Strontium, and the Actinides from Acidic Radioactive Waste|year=2001|last1=Romanovskiy|first1=Valeriy N.|last2=Smirnov|first2=Igor V.|last3=Babain|first3=Vasily A.|last4=Todd|first4=Terry A.|last5=Herbst|first5=R. Scott|last6=Law|first6=Jack D.|last7=Brewer|first7=Ken N.|journal=Solvent Extraction and Ion Exchange|volume=19|page=1|s2cid=98166395}}</ref> and a [[cobalt]] [[carborane]] [[anion]] (known as chlorinated cobalt dicarbollide). The actinides are extracted by CMPO, and the [[diluent]] is a polar [[aromatic]] such as [[nitrobenzene]]. Other diluents such as ''meta''-nitrobenzotri[[fluoride]]<ref>{{Cite conference |last=Smirnov |first=Igor |date=2–6 March 2014 |title=UNEX-T Solvent for Cs, Sr and Actinides Separation from PUREX Raffinate – 14154 |url=https://archivedproceedings.econference.io/wmsym/2014/papers/14154.pdf |conference=Waste Management Symposium |via=econference.io}}</ref> and phenyl trifluoromethyl [[sulfone]]<ref>{{cite web| url=http://www.wmsym.org/Abstracts/2001/62/62-7.pdf | archive-url=https://web.archive.org/web/20070928141036/http://www.wmsym.org/Abstracts/2001/62/62-7.pdf | archive-date=28 September 2007 | title=Flowsheet testing of the universal solvent extraction process for the simultaneous separation of caesium, strontium, and the actinides from dissolved INEEL calcine |author=J.D. Law| publisher=WM 2001 conference proceedings| date=1 March 2001|access-date=17 June 2006|display-authors=etal}}</ref> have been suggested as well.