Structural studies of the phase separation in the UO2–PuO2–Pu2O3 ternary system

Truphémus, Thibaut; Belin, Renaud C.; Richaud, Jean-Christophe; Reynaud, Muriel; Martinez, Marie-Annick; Felines, I.; Arredondo, Antoine; Miard, A.; Dubois, Thierry; Adenot, F.; Rogez, J.

doi:10.1016/j.jnucmat.2012.07.034

Cited by 45 publications

(32 citation statements)

References 32 publications

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“…23,24 Characterization of Substoichiometric MOX. The substoichiometric MOX U 0.7 Pu 0.3 O 2-x sample presents a biphasic composition (Figure 4), in agreement with previously reported experimental data 2,5,26,27 and the thermodynamic model. 28 While U 0.7 Pu 0.3 O 2-x is monophasic at high temperature during the sintering process, a phase separation occurs during the cooling step at relatively low temperature (ca.…”

Section: ■ Introductionsupporting

confidence: 91%

Structural Investigation of (U_0.7Pu_0.3)O_2-x Mixed Oxides

et al. 2015

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Uranium-plutonium mixed oxide containing 30% of plutonium is a candidate fuel for several fast neutron and accelerator driven reactor systems. In this work, a detailed structural investigation on sol-gel synthesized stoichiometric U0.7Pu0.3O2.00 and substoichiometric U0.7Pu0.3O2-x, using X-ray diffraction (XRD), oxygen 17 magic angle spinning nuclear magnetic resonance ((17)O MAS NMR) and X-ray absorption spectroscopy is described. As observed by XRD, the stoichiometric U0.7Pu0.3O2.00 is monophasic with a lattice parameter in good agreement with Vegard's law, while the substoichiometric U0.7Pu0.3O2-x material is biphasic. Solid solution ideality in terms of a random distribution of metal atoms is proven for U0.7Pu0.3O2.00 with (17)O MAS NMR. X-ray absorption near-edge structure (XANES) spectroscopy shows the presence of plutonium(III) in U0.7Pu0.3O2-x. Extended X-ray absorption fine-structure (EXAFS) spectroscopy indicates a similar local structure around both cations, and comparison with XRD indicates a close similarity between uranium and plutonium local structures and the long-range ordering.

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Section: ■ Introductionsupporting

confidence: 91%

Structural Investigation of (U_0.7Pu_0.3)O_2-x Mixed Oxides

et al. 2015

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“…A change to a hyperstoichiometric phase in PuO 2 -rich compositions, as one might expect from the higher oxygen potential of PuO 2 compared to ThO 2 , was not found. A reduction as seen by Truphmus et al [26] to three distinct phases for nonstoichiometric (U,Pu)O 2 could not be seen in that extent for (Pu,Th)O 2 . To explain the effects seen in this study only with oxygen related phenomena, one has to assume a slightly non stoichiometric section in the (Pu + Th + O) phase diagram as already suggested for mixed (U, Pu)O 2 [27,1], with a miscibility gap for non-stoichiometric material only for intermediate compositions.…”

Section: Powder X-ray Diffractionmentioning

confidence: 65%

High temperature phase transition of mixed (PuO 2 + ThO 2 ) investigated by laser melting

Böhler

Cakir

Beneš

et al. 2015

The Journal of Chemical Thermodynamics

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a b s t r a c tA laser heating approach combined with fast pyrometry in a thermal arrest method was used to provide new data for the melting/solidification phase transition in mixed (PuO 2 + ThO 2 ) at high temperature. At low concentration of ThO 2 in PuO 2 a minimum in the solidification temperature in the pseudo binary (PuO 2 + ThO 2 ) was observed. The minimum was found around a composition with 5 mol% ThO 2 . Phase transition temperatures of other compositions are closer to an ideal solution behaviour. To detect changes in the material a complete investigation with electron microscopy, Raman spectroscopy and powder X-ray diffraction was done. Raman vibration modes were found, that are characteristic for materials containing PuO 2 , and high temperature segregation effects during solidification were described. The results obtained in the present work are compared to other mixed actinide dioxides and compared to the ideal solution case for this system. The presented results show the importance of the hightemperature oxygen chemistry in this actinide oxide phase.

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“…Thus, determining the oxygen stoichiometry is of main interest for various applications, including production of nuclear oxide fuels [2]. In the UO 2 -PuO 2 -Pu 2 O 3 sub-system, U 1-y Pu y O 2-x mixed oxides with high plutonium content (> 0.20) are multiphasic at room temperature [3][4][5][6][7][8][9][10][11][12][13]. The miscibility gap is composed of two f.c.c.…”

Section: Introductionmentioning

confidence: 99%