Solution of trivalent cations into uranium dioxide

• Published in: Journal of nuclear materials Vol. 420; no. 1; pp. 258 - 261
• Main Authors: Middleburgh, S.C., Parfitt, D.C., Grimes, R.W., Dorado, B., Bertolus, M., Blair, P.R., Hallstadius, L., Backman, K.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 2012; Elsevier
• Subjects: Accommodation; Applied sciences; Cations; Clusters; Controled nuclear fusion plants; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fission nuclear power plants; Fuels; Installations for energy generation and conversion: thermal and electrical energy; Mathematical analysis; Nuclear fuels; Oxides; Preparation and processing of nuclear fuels; Simulation; Solubility; Uranium dioxide; Uranium; Solubility; Nuclear fuel; Vacancy cluster; Uranium dioxide; Uranium oxide; Oxygen ion; Nuclear reactor
• DOI: 10.1016/j.jnucmat.2011.10.006
• ISSN: 0022-3115

► Change in solubility limit of sesquioxides in uranium dioxide with excess oxygen. ► Larger trivalent cations found to be soluble regardless of stoichiometry and limit mainly temperature dependent. ► Iron and chromium cation solution limit strongly dependent on stoichiometry, only soluble with excess oxygen. ► Addition of trivalent cations removes oxygen excess. The accommodation of trivalent oxides (M 2O 3) in uranium dioxide has been investigated using atomic scale simulation. Calculations suggest that all trivalent oxides studied preferentially enter UO 2 by associating the substitutional ion with an oxygen vacancy, larger cations forming the cluster { 2 M U ′ : V O } × . Solution into hyper-stoichiometric UO 2+ x was accompanied by the formation of the { M U ′ : U U } × cluster and smaller solution energies than into stoichiometric UO 2. Solubility is a particularly strong function of hyper-stoichiometry for smaller cations such as Cr 3+, which has implications for the use of Cr 2O 3 as a grain enlarger but not so for larger cations such s Gd 3+.