MARIOS: Irradiation of UO2 containing 15% americium at well defined temperature

Elio, D'agata; Hania, P.R.; Béjaoui, S.; Sciolla, C.; Wyatt, T. R.; Hannink, M.H.C.; Herlet, Nathalie; Jankowiak, A.; Klaassen, F.M.; Bonnerot, J.M.

doi:10.1016/j.nucengdes.2011.10.016

Cited by 14 publications

(5 citation statements)

References 8 publications

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“…In the case of hypostoichiometric oxides, oxygen vacancies are expected to be the dominant defects. For both materials, the coordination value of the Me−Me shell is equal to 11.9 (5), indicating that the cation sublattice is not significantly affected by the sintering atmosphere, which would be expected.…”

Section: Resultsmentioning

confidence: 70%

“…Thus, Am is fissioned into short-lived isotopes in neutron flux. Because UO 2 is the most widely used fuel and there is already a strong database on its behavior under neutron irradiation, U 1– y Am y O 2– x materials have been studied for this purpose in the past few years , and test irradiation programs are ongoing. , Generally, Am contents of about 20% are considered because higher compositions can result in unsatisfactory sodium compatibility. Two recent X-ray absorption spectroscopy (XAS) studies have indicated that Am is strictly Am III in Am-bearing UO 2 solid solutions.…”

Section: Introductionmentioning

confidence: 99%

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Charge Distribution and Local Structure of Americium-Bearing Thorium Oxide Solid Solutions

Carvajal-Nunez

Prieur

Vitova³

et al. 2012

Inorg. Chem.

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The electronical and structural properties of Th(0.80)Am(0.20)O(2-x) materials have been studied by the coupling of X-ray diffraction and X-ray absorption spectroscopy techniques. A substoichiometric fluorite Th(IV)(0.80)Am(III)(0.20)O(1.90) solid solution is found following sintering in moisturized Ar-H(2). In contrast, heating of this sample in air leads to a nondefective fluorite Th(IV)(0.80)Am(IV)(0.20)O(2.00) solid solution. The structures of these solid solution compounds were fully characterized by assessing the interatomic distances, the coordination numbers, and the structural disorder. The effect of the sintering atmosphere on these crystallographical parameters and on the cation valences has been determined and the capability of ThO(2) to accommodate tri- and tetravalent actinides in the fluorite structure assessed.

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Section: Resultsmentioning

confidence: 70%

Section: Introductionmentioning

confidence: 99%

Charge Distribution and Local Structure of Americium-Bearing Thorium Oxide Solid Solutions

Carvajal-Nunez

Prieur

Vitova³

et al. 2012

Inorg. Chem.

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“…The structure of such compounds can thus be approximatively described based on those respectively reported for PuO 2−δ and UO 2+ε domains. Recent studies showed, however, that the case of U 1– x Am x O 2±δ compounds (currently investigated for potential use as americium-bearing transmutation targets for nuclear waste long-term radiotoxicity attenuation) − was different. Despite the similarities between plutonium and americium oxides (both exist for O/M ratios ranging from 1.5 to 2 with similar phase diagrams in the corresponding domains) and thus the stability of americium as both Am III+ and Am IV+ , several studies showed that Am III+ and U V+ cations coexist in single-phase U 1– x Am x O 2±δ compounds. − Using X-ray absorption near-edge spectroscopy (XANES), Prieur et al.…”

Section: Introductionmentioning

confidence: 99%

Peculiar Behavior of (U,Am)O_2−δ Compounds for High Americium Contents Evidenced by XRD, XAS, and Raman Spectroscopy

et al. 2015

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In U(1-x)Am(x)O(2±δ) compounds with low americium content (x ≤ 20 atom %) and oxygen-to-metal (O/M) ratios close to 2.0, Am(III+) cations are charge-balanced by an equivalent amount of U(V+) cations while the fluorite structure of pure U(IV+)O2 is maintained. Up to now, it is unknown whether this observation also holds for higher americium contents. In this study, we combined X-ray diffraction with Raman and X-ray absorption spectroscopies to investigate a U(0.5)Am(0.5)O(2±δ) compound. Our results indicate that americium is again only present as Am(III+), while U(V+) remains below the amount required for charge balance. Unlike lower americium contents, this leads to an overall oxygen hypostoichiometry with an average O/M ratio of 1.92(2). The cationic sublattice is only slightly affected by the coexistence of large amounts of reduced (Am(III+)) and oxidized (U(V+)) cations, whereas significant deviations from the fluorite structure are evidenced by both extended X-ray absorption fine structure and Raman spectroscopies in the oxygen sublattice, with the observation of both vacancies and interstitials, the latter being apparently consistent with the insertion of U6O12 cuboctahedral-type clusters (as observed in the U4O9 or U3O7 phases). These results thus highlight the specificities of uranium-americium mixed oxides, which behave more like trivalent lanthanide-doped UO2 than U(1-x)Pu(x)O(2±δ) MOX fuels.

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“…This option abates the long time scale influence of MAs in the waste by their separation from the spent fuel, their incorporation in new fuels and their irradiation in fast neutron reactors, where they are converted by fission to fission products, with in the main a much shorter half life. In this framework, U 1 À x Am x O 2 7 δ compounds are studied increasingly as promising materials for americium recycling in fast reactor systems [2,3]. The Am content will most likely be x r0.…”

Section: Introductionmentioning

confidence: 99%

Comparative XRPD and XAS study of the impact of the synthesis process on the electronic and structural environments of uranium–americium mixed oxides

Prieur

Lebreton

Martin

et al. 2015

Journal of Solid State Chemistry

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MARIOS: Irradiation of UO2 containing 15% americium at well defined temperature

Cited by 14 publications

References 8 publications

Charge Distribution and Local Structure of Americium-Bearing Thorium Oxide Solid Solutions

Charge Distribution and Local Structure of Americium-Bearing Thorium Oxide Solid Solutions

Peculiar Behavior of (U,Am)O_2−δ Compounds for High Americium Contents Evidenced by XRD, XAS, and Raman Spectroscopy

Comparative XRPD and XAS study of the impact of the synthesis process on the electronic and structural environments of uranium–americium mixed oxides

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MARIOS: Irradiation of UO2 containing 15% americium at well defined temperature

Cited by 14 publications

References 8 publications

Charge Distribution and Local Structure of Americium-Bearing Thorium Oxide Solid Solutions

Charge Distribution and Local Structure of Americium-Bearing Thorium Oxide Solid Solutions

Peculiar Behavior of (U,Am)O2−δ Compounds for High Americium Contents Evidenced by XRD, XAS, and Raman Spectroscopy

Comparative XRPD and XAS study of the impact of the synthesis process on the electronic and structural environments of uranium–americium mixed oxides

Contact Info

Product

Resources

About

Peculiar Behavior of (U,Am)O_2−δ Compounds for High Americium Contents Evidenced by XRD, XAS, and Raman Spectroscopy