Thermal expansion of the nuclear fuel-sodium reaction product Na3(U0.84(2),Na0.16(2))O4 - Structural mechanism and comparison with related sodium-metal ternary oxides

Marie Claire Illy, Anna L. Smith, Gilles Wallez, Philippe E. Raison, Roberto Caciuffo, Rudy J.M. Konings

Research output: Contribution to journalArticleScientificpeer-review

1 Citation (Scopus)

Abstract

Na3.16(2)UV,VI 0.84(2)O4 is obtained from the reaction of sodium with uranium dioxide under oxygen potential conditions typical of a sodium-cooled fast nuclear reactor. In the event of a breach of the steel cladding, it would be the dominant reaction product forming at the rim of the mixed (U,Pu)O2 fuel pellets. High-temperature X-ray diffraction measurements show that a distortion of the uranium environment in Na3.16(2)UV,VI 0.84(2)O4 results in a strongly anisotropic thermal expansion. A comparison with several related sodium metallates Nan-2Mn+On-1 - including Na3SbO4 and Na3TaO4, whose crystal structures are reported for the first time - has allowed us to assess the role played in the lattice expansion by the Mn+ cation radius and the Na/M ratio. On this basis, the thermomechanical behavior of the title compound is discussed, along with those of several related double oxides of sodium and actinide elements, surrogate elements, or fission products.

Original languageEnglish
Pages (from-to)101-107
Number of pages7
JournalJournal of Nuclear Materials
Volume490
DOIs
Publication statusPublished - 1 Jul 2017

Keywords

  • Crystal structures
  • Sodium-cooled fast reactors
  • Thermal expansion

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