Title
Assessment of solid/liquid equilibria in the (U, Zr)O2+y system
Author
Mastromarino, S. (TU Delft RST/Reactor Physics and Nuclear Materials; European Commission Joint Research Centre, Institute for Transuranium Elements Karlsruhe; Università“La Sapienza”)
Seibert, AF (European Commission Joint Research Centre, Institute for Transuranium Elements Karlsruhe)
Hashem, E. (European Commission Joint Research Centre, Institute for Transuranium Elements Karlsruhe)
Ciccioli, A. (Sapienza University of Rome)
Prieur, Damien (European Commission Joint Research Centre, Institute for Transuranium Elements Karlsruhe)
Scheinost, Andreas C. (Institute of Ion Beam Physics and Materials Research)
Stohr, S. (European Commission Joint Research Centre, Institute for Transuranium Elements Karlsruhe)
Lajarge, P (European Commission Joint Research Centre, Institute for Transuranium Elements Karlsruhe)
Boshoven, JG (European Commission Joint Research Centre, Institute for Transuranium Elements Karlsruhe)
Robba, D. (European Commission Joint Research Centre, Institute for Transuranium Elements Karlsruhe)
Ernstberger, M (European Commission Joint Research Centre, Institute for Transuranium Elements Karlsruhe)
Bottomley, D. (European Commission Joint Research Centre, Institute for Transuranium Elements Karlsruhe)
Manara, D (European Commission Joint Research Centre, Institute for Transuranium Elements Karlsruhe)
Date
2017-10-01
Abstract
Solid/liquid equilibria in the system UO2–ZrO2 are revisited in this work by laser heating coupled with fast optical thermometry. Phase transition points newly measured under inert gas are in fair agreement with the early measurements performed by Wisnyi et al., in 1957, the only study available in the literature on the whole pseudo-binary system. In addition, a minimum melting point is identified here for compositions near (U0.6Zr0.4)O2+y, around 2800 K. The solidus line is rather flat on a broad range of compositions around the minimum. It increases for compositions closer to the pure end members, up to the melting point of pure UO2 (3130 K) on one side and pure ZrO2 (2970 K) on the other. Solid state phase transitions (cubic-tetragonal-monoclinic) have also been observed in the ZrO2-rich compositions X-ray diffraction. Investigations under 0.3 MPa air (0.063 MPa O2) revealed a significant decrease in the melting points down to 2500 K–2600 K for increasing uranium content (x(UO2)> 0.2). This was found to be related to further oxidation of uranium dioxide, confirmed by X-ray absorption spectroscopy. For example, a typical oxidised corium composition U0.6Zr0.4O2.13 was observed to solidify at a temperature as low as 2493 K. The current results are important for assessing the thermal stability of the system fuel – cladding in an oxide based nuclear reactor, and for simulating the system behaviour during a hypothetical severe accident.
Subject
Core meltdown
Corium
Laser heating
Nuclear fuel
Uranium dioxide
Zirconium dioxide
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http://resolver.tudelft.nl/uuid:c9daf2b7-4854-4395-92ef-c087103e69e1
DOI
https://doi.org/10.1016/j.jnucmat.2017.07.045
ISSN
0022-3115
Source
Journal of Nuclear Materials, 494, 368-379
Part of collection
Institutional Repository
Document type
journal article
Rights
© 2017 S. Mastromarino, AF Seibert, E. Hashem, A. Ciccioli, Damien Prieur, Andreas C. Scheinost, S. Stohr, P Lajarge, JG Boshoven, D. Robba, M Ernstberger, D. Bottomley, D Manara