An X-ray absorption spectroscopy study of yttrium and zirconium complexes in molten lithium chloride / Volkovich V.A., May I., Griffiths T.R., Charnock J.M., Lewin B. // Proceedings - Electrochemical Society. - 2006. - V. PV 2004-24, l. . - P. 162-170.

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Conference Paper

Abstract:

Pyrochemical reprocessing of spent nuclear fuels in molten salts is a promising and potential alternative to the modern day extraction technology. A key factor for developing a safe and effective process is the understanding of the behaviour and basic chemistry of the components of irradiated fuels, including fission products. Inorganic melts have high radiation stability and this allows reprocessing of fuels after a relatively short cooling time. Yttrium and zirconium isotopes are formed with high yields as fission products and as products of the β-decay of isotopes of Sr and Y, respectively. We have investigated LiCl-based melts containing chlorides of yttrium or zirconium by X-ray absorption spectroscopy, XAS, (both EXAFS and XANES) at 750°C. Yttrium-containing melts were prepared by reacting Y2O3 with HCl and analysis of EXAFS data showed that each Y atom was surrounded by six Cl atoms at ca. 2.62 Å and two Y atoms at ca. 4 Å. At the concentration employed, neighbouring YCI6 3- octahedra share two Cl ligands and the Cl-Y-Cl angle is around 80°. Zirconium has two stable oxidation states in chloride melts, Zr(II) and Zr(IV). Zr(IV)-containing melts, from dissolving anhydrous ZrCl4 in LiCl, contained ZrCl 6 2- species with Zr-Cl distances of 2.27 Å. Melt samples containing only Zr(II) could not be prepared but by slowly reacting Zr metal with Cl2 in molten LiCl, and then holding the melt in contact with excess Zr; 25% of the zirconium in the melt was reduced to Zr(II). The energy of Zr K-edge for such samples was shifted towards lower values by ca. 6 eV, compared to Zr(IV), but was still 6 eV higher than for Zr(O). The analysis of EXAFS data showed that the first coordination sphere of zirconium for the mixed Zr(II,IV) containing melts is filled by six Cl ligands with an average Zr-Cl distance of 2.45 Å.

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Index keywords:

Absorption spectroscopy; Concentration (process); Fission products; Lithium compounds; Molten materials; Nuclear fuels; Zirconium compounds; Molten lithium chloride; Pyrochemical reprocessing; Zirconi

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Link	https://www.scopus.com/inward/record.uri?eid=2-s2.0-40249112232&partnerID=40&md5=2005b8aaad5b48c2eda915dfedd92d25
Affiliations	Department of Rare Metals, Ural State Technical University - UPI, Ekaterinburg, 620002, Russian Federation; Centre for Radiochemistry Research, University of Manchester, Manchester, M13 9PL, United Kingdom; Redston Trevor Consulting Ltd., University of Leeds, Leeds, LS2 9JT, United Kingdom; CLRC Daresbury Laboratory, Warrington, WA4 4AD, United Kingdom; British Nuclear Fuels Plc., Sellafield, Cumbria, CA20 1PG, United Kingdom
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Correspondence Address	Volkovich, V.A.; Department of Rare Metals, Ural State Technical University - UPI, Ekaterinburg, 620002, Russian Federation
Sponsors	Electrochemical Society Inc, Physical Electrochemistry Division;Electrochemical Society Inc, High Temperature Materials Division;Electrochemical Society Inc, Electrodeposition Division
Conference name	206th ECS Meeting
Conference date	3 October 2004 through 8 October 2004
Conference location	Honolulu, HI
Conference code	71459
ISBN	9781566775144
Language of Original Document	English
Abbreviated Source Title	Proc. Electrochem. Soc.
Source	Scopus