The thermal decomposition of studtite: analysis of the amorphous phase

Abstract

Studtite is known to exist at the back-end of the nuclear fuel cycle as an intermediate phase formed in the reprocessing of spent nuclear fuel. In the thermal decomposition of studtite, an amorphous phase is obtained at calcination temperatures between 200 and 500 °C. This amorphous compound, referred to elsewhere in the literature as U2O7, has been characterised by analytical spectroscopic methods. The local structure of the amorphous compound has been found to contain uranyl bonding by X-ray absorption near edge (XANES), Fourier transform infrared and Raman spectroscopy. Changes in bond distances in the uranyl group are discussed with respect to studtite calcination temperature. The reaction of the amorphous compound with water to form metaschoepite is also discussed and compared with the structure of schoepite and metaschoepite by X-ray diffraction. A novel schematic reaction mechanism for the thermal decomposition of studtite is proposed.

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Item Type:	Article
Authors/Creators:	Thompson, N.B.A. Frankland, V.L. Bright, J.W.G. Read, D. Gilbert, M.R. Stennett, M.C. https://orcid.org/0000-0002-8363-9103 Hyatt, N.C.
Copyright, Publisher and Additional Information:	© The Author(s) 2021. Open Access: This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
Keywords:	Studtite; Thermal decomposition; Spectroscopy; Uranium oxide
Dates:	Published: March 2021 Published (online): 15 February 2021 Accepted: 15 January 2021
Institution:	The University of Sheffield
Academic Units:	The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Materials Science and Engineering (Sheffield)
Funding Information:	Funder Grant number ENGINEERING AND PHYSICAL SCIENCE RESEARCH COUNCIL EP/P013600/1 EPSRC EP/L015390/1 ENGINEERING AND PHYSICAL SCIENCE RESEARCH COUNCIL EP/S011935/1 Engineering and Physical Sciences Research Council EP/P02470X/1
Depositing User:	Symplectic Sheffield
Date Deposited:	16 Apr 2021 11:34
Last Modified:	16 Apr 2021 11:34
Status:	Published
Publisher:	Springer Science and Business Media LLC
Refereed:	Yes
Identification Number:	10.1007/s10967-021-07611-4
Open Archives Initiative ID (OAI ID):	oai:eprints.whiterose.ac.uk:173163

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The thermal decomposition of studtite: analysis of the amorphous phase

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