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{{Short description|Branch of chemistry
[[File:Alpha Decay.svg|thumb|[[Alpha decay]] is one type of radioactive decay, in which an atomic nucleus emits an [[alpha particle]], and thereby transforms (or "decays") into an atom with a [[mass number]] decreased by 4 and [[atomic number]] decreased by 2.]]
'''Nuclear chemistry''' is the sub-field of [[chemistry]] dealing with [[radioactivity]], nuclear processes, and transformations in the nuclei of atoms, such as [[nuclear transmutation]] and nuclear properties.
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It includes the study of the chemical effects resulting from the absorption of radiation within living animals, plants, and other materials. The [[radiation chemistry]] controls much of [[radiation biology]] as radiation has an effect on living things at the molecular scale. To explain it another way, the radiation alters the biochemicals within an organism, the alteration of the bio-molecules then changes the chemistry which occurs within the organism; this change in [[chemistry]] then can lead to a biological outcome. As a result, nuclear chemistry greatly assists the understanding of medical treatments (such as [[cancer]] [[radiotherapy]]) and has enabled these treatments to improve.
It includes the study of the production and use of radioactive sources for a range of processes. These include [[radiotherapy]] in medical applications; the use of [[radioactive tracer]]s within industry, science and the environment, and the use of radiation to modify materials such as [[polymer]]s.<ref>{{cite
It also includes the study and use of nuclear processes in ''non-radioactive'' areas of human activity. For instance, [[nuclear magnetic resonance]] (NMR) spectroscopy is commonly used in synthetic [[organic chemistry]] and [[physical chemistry]] and for structural analysis in [[macromolecular chemistry|macro-molecular chemistry]].
==History==
After [[Wilhelm Röntgen]] discovered [[X-ray]]s in
[[Ernest Rutherford]], working in Canada and England, showed that radioactive decay can be described by a simple equation (a linear first degree derivative equation, now called [[Rate equation#First
In 1934, [[Marie Curie]]'s daughter ([[Irène Joliot-Curie]]) and son-in-law ([[Frédéric Joliot-Curie]]) were the first to create [[artificial radioactivity]]: they bombarded [[boron]] with alpha particles to make the neutron-poor isotope [[nitrogen-13]]; this isotope emitted [[positron]]s.<ref>{{cite web|url=http://nobelprize.org/nobel_prizes/chemistry/laureates/1935/joliot-fred-bio.html|title=Frédéric Joliot - Biographical|website=nobelprize.org|access-date=1 April 2018}}</ref> In addition, they bombarded [[aluminium]] and [[magnesium]] with [[neutrons]] to make new radioisotopes.
In the early 1920s [[Otto Hahn]] created a new line of research. Using the "emanation method", which he had recently developed, and the "emanation ability", he founded what became known as "applied radiochemistry" for the researching of general chemical and physical-chemical questions. In 1936 Cornell University Press published a book in English (and later in Russian) titled ''[[Applied Radiochemistry]]'', which contained the lectures given by Hahn when he was a visiting professor at [[Cornell University]] in [[Ithaca, New York]], in 1933. This important publication had a major influence on almost all nuclear chemists and physicists in the United States, the United Kingdom, France, and the Soviet Union during the 1930s and 1940s, laying the foundation for modern nuclear chemistry.<ref>{{cite book|title=Otto Hahn: A Scientific Autobiography |editor-last1=Ley|editor-first1=Willy |publisher=C. Scribner's Sons|last1=Hahn|first1=Otto|date=1966|pages=ix–x}}</ref>
==Main areas==
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===Radiation chemistry===
[[Radiation chemistry]] is the study of the chemical effects of radiation on
Initial experiments were focused on understanding the effects of radiation on matter. Using a X-ray generator, [[:de:Hugo Fricke|Hugo Fricke]] studied the biological effects of radiation as it became a common treatment option and diagnostic method.<ref name=":0" /> Fricke proposed and subsequently proved that the energy from X - rays were able to convert water into activated water, allowing it to react with dissolved species.<ref>{{Cite journal|last=Allen|first=A. O.|date=September 1962|title=Hugo Fricke and the Development of Radiation Chemistry: A Perspective View|url=https://www.osti.gov/biblio/12490813|journal=Radiation Chemistry|volume=17|issue=3|pages=254–261|doi=10.2307/3571090|osti=12490813|jstor=3571090|bibcode=1962RadR...17..254A}}</ref>
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{{see also|nuclear physics|nuclear reactions}}
A combination of
=== The nuclear fuel cycle ===
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A complex bond is formed between the metal cation, the nitrates and the tributyl phosphate, and a model compound of a dioxouranium(VI) complex with two nitrate anions and two triethyl phosphate ligands has been characterised by [[X-ray crystallography]].<ref>J.H. Burns, "Solvent-extraction complexes of the uranyl ion. 2. Crystal and molecular structures of catena-bis(.mu.-di-n-butyl phosphato-O,O')dioxouranium(VI) and bis(.mu.-di-n-butyl phosphato-O,O')bis[(nitrato)(tri-n-butylphosphine oxide)dioxouranium(VI)]", ''Inorganic Chemistry'', 1983, '''22''', 1174-1178</ref>
When the nitric acid concentration is high the extraction into the organic phase is favored, and when the nitric acid concentration is low the extraction is reversed (the organic phase is ''stripped'' of the metal). It is normal to dissolve the used fuel in nitric acid, after the removal of the insoluble matter the uranium and plutonium are extracted from the highly active liquor. It is normal to then back extract the loaded organic phase to create a ''medium active'' liquor which contains mostly uranium and plutonium with only small traces of fission products. This medium active aqueous mixture is then extracted again by tributyl phosphate/hydrocarbon to form a new organic phase, the metal bearing organic phase is then stripped of the metals to form an aqueous mixture of only uranium and plutonium. The two stages of extraction are used to improve the purity of the [[actinide]] product, the organic phase used for the first extraction will suffer a far greater dose of radiation. The radiation can degrade the tributyl phosphate into dibutyl hydrogen phosphate. The dibutyl hydrogen phosphate can act as an extraction agent for both the actinides and other metals such as [[ruthenium]]. The dibutyl hydrogen phosphate can make the system behave in a more complex manner as it tends to extract metals by an [[ion exchange]] mechanism (extraction favoured by low acid concentration), to reduce the effect of the dibutyl hydrogen phosphate it is common for the used organic phase to be washed with [[sodium carbonate]] solution to remove the acidic degradation products of the tributyl
=====New methods being considered for future use=====
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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 this is a process which 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 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.
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]]. 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. In common with PUREX this process operates by a solvation mechanism.<ref>
Selective Actinide Extraction (SANEX). As part of the management of minor actinides, it has been proposed that the [[lanthanides]] and trivalent minor [[actinides]] should be removed from the PUREX [[raffinate]] by a process such as DIAMEX or TRUEX. In order 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.
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Other systems such as the dithiophosphinic acids are being worked on by some other workers.
This is the ''UNiversal'' ''EX''traction process which was developed in Russia and the Czech Republic, it is a process designed to remove all of the most troublesome (Sr, Cs and [[minor actinides]]) [[radioisotopes]] from the raffinates left after the extraction of uranium and plutonium from used [[nuclear fuel]].<ref>{{cite web |url=http://www.usembassy.it/file2001_12/alia/a1121910.htm |title=
====Absorption of fission products on surfaces====
Another important area of nuclear chemistry is the study of how fission products interact with surfaces; this is thought to control the rate of release and migration of fission products both from waste containers under normal conditions and from power reactors under accident conditions. Like [[Chromate ion|chromate]] and [[molybdate]], the '''<sup>99</sup>TcO<sub>4</sub>''' anion can react with steel surfaces to form a [[corrosion]] resistant layer. In this way, these metaloxo anions act as [[anode|anodic]] [[corrosion inhibitor]]s. The formation of <sup>99</sup>TcO<sub>2</sub> on steel surfaces is one effect which will retard the release of <sup>99</sup>Tc from nuclear waste drums and nuclear equipment which has been lost before decontamination (e.g. [[submarine]] reactors lost at sea). This <sup>99</sup>TcO<sub>2</sub> layer renders the steel surface passive, inhibiting the [[anodic]]
<sup>99</sup>Tc in nuclear waste may exist in chemical forms other than the <sup>99</sup>TcO<sub>4</sub> anion, these other forms have different chemical properties.<ref>
Similarly, the release of iodine-131 in a serious power reactor accident could be retarded by absorption on metal surfaces within the nuclear plant.<ref>Glänneskog H (2004) Interactions of [[Iodine|I]]<sub>2</sub> and [[Methyl iodide|CH]]<sub>3</sub>I with reactive metals under BWR severe-accident conditions. ''Nuclear Engineering and Design'' '''227''':323-9</ref><ref>Glänneskog H (2005) Iodine chemistry under severe accident conditions in a nuclear power reactor, PhD thesis, Chalmers University of Technology, Sweden</ref><ref>{{cite web|url=http://www.sbf.admin.ch/htm/services/publikationen/international/frp/eu-abstracts/html/fp/fp5/5eu99.0423.html|title=Im Brennpunkt|first=Staatssekretariat für Bildung, Forschung und Innovation|last=SBFI|website=www.sbf.admin.ch|access-date=1 April 2018}}</ref><ref>{{Cite web|url=http://www.nea.fr/html/nsd/docs/2000/csni-r2000-12.pdf|title = Workshop on Iodine Aspects of Severe Accident Management - Summary and Conclusions,18-20 May 1999, Vantaa, Finland}}</ref><ref>{{cite web |url=http://www.ing.unipi.it/~dimnp/CD/supporto/pdf/paci03.pdf |title=Archived copy |access-date=2007-11-13 |archive-url=https://web.archive.org/web/20070710105844/http://www2.ing.unipi.it/~dimnp/CD/supporto/pdf/paci03.pdf |archive-date=2007-07-10
== Education ==
Despite the growing use of nuclear medicine, the potential expansion of nuclear power plants, and worries about protection against nuclear threats and the management of the nuclear waste generated in past decades, the number of students opting to specialize in nuclear and radiochemistry has decreased significantly over the past few decades. Now, with many experts in these fields approaching retirement age, action is needed to avoid a workforce gap in these critical fields, for example by building student interest in these careers, expanding the educational capacity of universities and colleges, and providing more specific on-the-job training.<ref>{{Cite book|title = Assuring a Future U.S.-Based Nuclear and Radiochemistry Expertise|publisher = Board on Chemical Sciences and Technology|year = 2012|isbn = 978-0-309-22534-2}}</ref>
Nuclear and Radiochemistry (NRC) is mostly being taught at university level, usually first at the Master- and PhD-degree level. In Europe, as substantial effort is being done to harmonize and prepare the NRC education for the industry's and society's future needs. This effort is being coordinated in a project funded by the Coordinated Action supported by the European Atomic Energy Community's 7th Framework Program.<ref>{{cite web|url=http://cinch-project.eu/index.php|title=www.cinch-project.eu|website=cinch-project.eu|access-date=1 April 2018|archive-url=https://web.archive.org/web/20150813134018/http://cinch-project.eu/index.php|archive-date=13 August 2015
==Spinout areas==
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