Solution of trivalent cations into uranium dioxide

Middleburgh, Simon C.; Parfitt, David; Grimes, Robin W.; Dorado, Boris; Bertolus, Marjorie; Blair, Paul; Hallstadius, Lars; Backman, K.

doi:10.1016/j.jnucmat.2011.10.006

Cited by 44 publications

(30 citation statements)

References 22 publications

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“…In the latter case, although configurational long-range order is absent on the cation and anion sublattices, experimental studies based on advanced structural characterization and thermochemistry techniques (e.g., refs 4, 5, 6, 7, 8 and references therein) have documented in several systems the presence of significant short-range order, i.e., local association and clustering of the different ionic species and oxygen vacancies. These experimental studies have been augmented by atomic-scale computational investigations (e.g., refs 9, 10, 11, 12, 13, 14, 15, 16 and references therein), which have established preferred structural motifs and associated energetic driving forces for defect association and compositional ordering across a broad range of chemistries.…”

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confidence: 99%

Chemical ordering in substituted fluorite oxides: a computational investigation of Ho2Zr2O7 and RE2Th2O7 (RE=Ho, Y, Gd, Nd, La)

Solomon

Shamblin

Lang

et al. 2016

Sci Rep

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Fluorite-structured oxides find widespread use for applications spanning nuclear energy and waste containment, energy conversion, and sensing. In such applications the host tetravalent cation is often partially substituted by trivalent cations, with an associated formation of charge-compensating oxygen vacancies. The stability and properties of such materials are known to be influenced strongly by chemical ordering of the cations and vacancies, and the nature of such ordering and associated energetics are thus of considerable interest. Here we employ density-functional theory (DFT) calculations to study the structure and energetics of cation and oxygen-vacancy ordering in Ho2Zr2O7. In a recent neutron total scattering study, solid solutions in this system were reported to feature local chemical ordering based on the fluorite-derivative weberite structure. The calculations show a preferred chemical ordering qualitatively consistent with these findings, and yield values for the ordering energy of 9.5 kJ/mol-cation. Similar DFT calculations are applied to additional RE2Th2O7 fluorite compounds, spanning a range of values for the ratio of the tetravalent and trivalent (RE) cation radii. The results demonstrate that weberite-type order becomes destabilized with increasing values of this size ratio, consistent with an increasing energetic preference for the tetravalent cations to have higher oxygen coordination.

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confidence: 99%

Chemical ordering in substituted fluorite oxides: a computational investigation of Ho2Zr2O7 and RE2Th2O7 (RE=Ho, Y, Gd, Nd, La)

Solomon

Shamblin

Lang

et al. 2016

Sci Rep

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“…The solution energy for Zr 3 Si to enter amorphous U 3 Si was calculated to be 0.78 eV. This is a moderate energy, consistent with a small concentration of Zr held within the amorphous U 3 Si structure with a small entropic contributions (similar to the partially soluble fission products such as La in UO 2 [22]) and the remainder forming a Zr containing precipitate (Zr 3 Si being the likely binary compound).…”

Section: Accommodation In Amorphous U 3 Simentioning

confidence: 80%

“…A huge amount of work has been carried out to understand the behaviour of fission products in UO 2 , both experimentally [18,19] and theoretically [20][21][22]. To qualify new fuels for use in commercial reactors, equivalent data is required for the development of a safety case.…”

Section: Introductionmentioning

confidence: 99%

Structural stability and fission product behaviour in U3Si

Middleburgh

Burr

King

et al. 2015

Journal of Nuclear Materials

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“…Partition energy calculations for FPs show that Ce 4+ and Y 3+ will remain in the UO 2 phase, whereas, Ru 4+ , Mo 4+ , Nd 3+ and La 3+ will preferentially segregate to the BaZrO 3 phase. [8,10,11]. This trend is slightly different for SrZrO 3 , where partition energies predict than Nd 3+ and La 3+ prefer to be dissolved into UO 2 .…”

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confidence: 90%

Preparation and characterization of UO₂-based AGR SIMFuel

2014

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Preparation and characterization of a Simulated Spent Nuclear Fuel (SIMFuel), which replicates the chemical state and microstructure of Spent Nuclear Fuel (SNF) discharged from UK Advanced Gas-cooled Reactor (AGR) after a cooling time of 100 years is described. Thirteen stable elements were added to depleted UO 2 and sintered to simulate the composition of fuel pellets after burn-ups of 25 and 43 GWd/tU and, as a reference, pure UO 2 pellets were also investigated. The fission product distribution was calculated using the Fispin code provided by NNL. SIMFuel pellets exhibit a microstructure up to 92% TD. During the sintering process in H 2 atmosphere Mo-Ru-Rh-Pd metallic precipitates and grey-phase ((Ba, Sr)(Zr, RE)O 3 oxide precipitates) formed within the UO 2 matrix. These secondary phases are present in real PWR and AGR SNF, although they are smaller in size than those examined in this study. The grain size of the produced SIMFuel is in good agreement with literature references.

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Solution of trivalent cations into uranium dioxide

Cited by 44 publications

References 22 publications

Chemical ordering in substituted fluorite oxides: a computational investigation of Ho2Zr2O7 and RE2Th2O7 (RE=Ho, Y, Gd, Nd, La)

Chemical ordering in substituted fluorite oxides: a computational investigation of Ho2Zr2O7 and RE2Th2O7 (RE=Ho, Y, Gd, Nd, La)

Structural stability and fission product behaviour in U3Si

Preparation and characterization of UO₂-based AGR SIMFuel

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Solution of trivalent cations into uranium dioxide

Cited by 44 publications

References 22 publications

Chemical ordering in substituted fluorite oxides: a computational investigation of Ho2Zr2O7 and RE2Th2O7 (RE=Ho, Y, Gd, Nd, La)

Chemical ordering in substituted fluorite oxides: a computational investigation of Ho2Zr2O7 and RE2Th2O7 (RE=Ho, Y, Gd, Nd, La)

Structural stability and fission product behaviour in U3Si

Preparation and characterization of UO2-based AGR SIMFuel

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Preparation and characterization of UO₂-based AGR SIMFuel