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PRINCIPAL PUBLICATION AND AUTHORS

Deconvoluting Cr states in Cr-doped UO2 nuclear fuels via bulk and single crystal spectroscopic studies, G.L. Murphy (a), R. Gericke (b), S. Gilson (b), E.F. Bazarkina (b,c), A. Rossberg (b,c), P. Kaden (b), R. Thümmler (a), M. Klinkenberg (a), M. Henkes (a), P. Kegler (a), V. Svitlyk (b,c), J. Marquardt (d), T. Lender (e), C. Hennig (b,c), K.O. Kvashnina (b,c), N. Huittinen (b), Nat. Commun. 14(1), 2455 (2023); https:/doi.org/10.1038/s41467-023-38109-0 (a) Institute of Energy and Climate Research (IEK-6), Forschungszentrum Jülich GmbH (Germany) (b) Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf (Germany) (c) ESRF (d) Institut für Geowissenschaften, Goethe-Universität Frankfurt (Germany) (e) Institut für Kristallographie, RWTH Aachen University (Germany)

REFERENCES

[1] C. Riglet-Martial et al., J. Nucl. Mater. 447(1-3), 63-72 (2014). [2] C. Mieszczynski et al., J. Phys: Condens. Matter 26(35), 355009- 355017 (2014).

in addition to lattice-incorporated (Cr+3xU+41-x)O2-0.5x. The measurement of extracted single crystals enabled the actual lattice matrix Cr chemical state to be clearly and unambiguously determined while accounting for secondary Cr states in the investigations of the bulk powder sample. This further allowed discrepancies in the literature, which proposed other Cr redox states in the UO2 matrix, to be understood and corrected. The quantitative identification and deconvolution of Cr chemical states in Cr-doped UO2 was further found to be consistent with proposed thermodynamic models [1].

The findings of this investigation provide the first direct, incontrovertible description of the chemical states of Cr within fresh Cr-doped UO2 nuclear fuel. Additionally, by cross-comparing the results of the investigation against previous studies examining spent reactor irradiated Cr-UO2 nuclear fuel [2], the Cr chemical states and chemistry therein were further identified and resolved. Consequently, this investigation has created significant guidance for the safe application of Cr-doped UO2 nuclear fuels for power generation and for their correct disposal when discharged from a reactor as spent nuclear fuel.

Fig. 113: HERFD-XANES spectra and simulated iterative transformation factor analysis components of (a) a single-crystal grain and (b) bulk Cr-doped UO2, where the former sample is extracted from the latter. Fourier transformations in R-space derived from EXAFS

analysis of both samples respectively are given in (c) and (d).