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Melting behaviour of uranium-americium mixed oxides under different atmospheres

Epifano, E.; Prieur, D.; Martin, P.M.; Guéneau, C.; Dardenne, K.; Rothe, J.; Vitova, T.; Dieste, O.; Wiss, T.; Konings, R.J.M.; Manara, D.

Abstract:
In the context of a comprehensive campaign for the characterisation of transmutation fuels for next generation nuclear reactors, the melting behaviour of mixed uranium-americium dioxides has been experimentally studied for the first time by laser heating, for Am concentrations up to 70 mol. % under different types of atmospheres. Extensive post-melting material characterisations were then performed by X-ray absorption spectroscopy and electron microscopy. The melting temperatures observed for the various compositions follow a markedly different trend depending on the experimental atmosphere. Uranium-rich samples melt at temperatures significantly lower (around 2700 K) when they are laser-heated in a strongly oxidizing atmosphere compressed air at (0.300 ± 0.005) MPa, compared to the melting points (beyond 3000 K) registered for the same compositions in an inert environment (pressurised Ar). This behaviour has been interpreted on the basis of the strong oxidation of such samples in air, leading to lower-melting temperatures. Thus, the melting temperature trend observed in air is characterized, in the purely pseudo-binary dioxide plane, by an apparent maximum melting temperature around 2850 K for 0.3 < x(AmO2) < 0.5. ... mehr

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Verlagsausgabe §
DOI: 10.5445/IR/1000097740
Veröffentlicht am 15.11.2019
Coverbild
Zugehörige Institution(en) am KIT Institut für Nukleare Entsorgung (INE)
Publikationstyp Zeitschriftenaufsatz
Jahr 2019
Sprache Englisch
Identifikator ISSN: 0021-9614
KITopen-ID: 1000097740
HGF-Programm 32.01.04 (POF III, LK 01)
Erschienen in The journal of chemical thermodynamics
Band 140
Seiten 105896
Vorab online veröffentlicht am 08.08.2019
Externe Relationen Abstract/Volltext
Schlagworte Uranium americium dioxide, Melting, Transmutation targets, CALPHAD
Nachgewiesen in Web of Science
Scopus
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