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Cr2+ solid solution in UO2 evidenced by advanced spectroscopy

DOI: 10.1038/s42004-022-00784-3 DOI Help

Authors: Hannah Smith (The University of Sheffield) , Luke T. Townsend (The University of Sheffield) , Ritesh Mohun (The University of Sheffield) , Théo Cordara (The University of Sheffield) , Martin C. Stennett (The University of Sheffield) , J. Frederick W. Mosselmans (Diamond Light Source) , Kristina Kvashnina (Helmholtz-Zentrum Dresden-Rossendorf (HZDR); ESRF – The European Synchrotron) , Claire L. Corkhill (The University of Sheffield)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Communications Chemistry , VOL 5

State: Published (Approved)
Published: December 2022
Diamond Proposal Number(s): 20872 , 24074 , 28515

Open Access Open Access

Abstract: Advanced Cr-doped UO2 fuels are essential for driving safe and efficient generation of nuclear energy. Although widely deployed, little is known about their fundamental chemistry, which is a critical gap for development of new fuel materials and radioactive waste management strategies. Utilising an original approach, we directly evidence the chemistry of Cr(3+)2O3–doped U(4+)O2. Advanced high-flux, high-spectral purity X-ray absorption spectroscopy (XAS), corroborated by diffraction, Raman spectroscopy and high energy resolved fluorescence detection-XAS, is used to establish that Cr2+ directly substitutes for U4+, accompanied by U5+ and oxygen vacancy charge compensation. Extension of the analysis to heat-treated simulant nuclear fuel reveals a mixed Cr2+/3+ oxidation state, with Cr in more than one physical form, explaining the substantial discrepancies that exist in the literature. Successful demonstration of this analytical advance, and the scientific underpinning it provides, opens opportunities for an expansion in the range of dopants utilised in advanced UO2 fuels.

Subject Areas: Chemistry, Materials, Energy

Instruments: B18-Core EXAFS , I20-Scanning-X-ray spectroscopy (XAS/XES)

Other Facilities: BM20 at ESRF

Added On: 08/12/2022 09:32


Discipline Tags:

Earth Sciences & Environment Radioactive Materials Energy Chemistry Materials Science Nuclear Waste Inorganic Chemistry

Technical Tags:

Spectroscopy X-ray Absorption Spectroscopy (XAS) Extended X-ray Absorption Fine Structure (EXAFS) X-ray Absorption Near Edge Structure (XANES)