Atomic scale analysis of defect clustering and predictions of their concentrations in UO2+x

JOURNAL OF NUCLEAR MATERIALS

卷:541

Article

Caglak, Emre^1,2  Govers, Kevin^2,4  Lamoen, Dirk³  Labeau, Pierre-Etienne¹  Verwerft, Marc² 

[1] Univ Libre Bruxelles, Serv Metrol Nucl, CP 165-84,50 Av FD Roosevelt, B-1050 Brussels, Belgium

[2] SCK CEN, Nucl Mat Sci Inst, Belgian Nucl Res Ctr, Boeretang 200, B-2400 Mol, Belgium

[3] Univ Antwerp, Dept Phys, EMAT, Groenenborgerlaan 171, B-2020 Antwerp, Belgium

[4] Fed Agcy Nucl Control FANC, Brussels, Belgium

关键词: Uranium dioxide;    Point defects;    Defect clustering;    Defect chemistry;    Deviation from stoichiometry;   

DOI  :  10.1016/j.jnucmat.2020.152403

来源: Elsevier

【 摘 要 】

The physical properties of uranium dioxide vary greatly with stoichiometry. Oxidation towards hyper-stoichiometric UO2 - UO2+x - might be encountered at various stages of the nuclear fuel cycle if oxidative conditions are met; the impact of stoichiometry changes upon physical properties should therefore be properly assessed to ensure safe and reliable operations. These physical properties are intimately linked to the arrangement of atomic defects in the crystalline structure. The evolution of the defect concentration with environmental parameters - oxygen partial pressure and temperature - were evaluated by means of a point defect model where the reaction energies are derived from atomic-scale simulations. To this end, various configurations and net charge states of oxygen interstitial clusters in UO2 have been calculated. Various methodologies have been tested to determine the optimum cluster configurations and a rigid lattice approach turned out to be the most useful strategy to optimize defect configuration structures. Ultimately, results from the point defect model were discussed and compared to experimental measurements of stoichiometry dependence on oxygen partial pressure and temperature. (C) 2020 Elsevier B.V. All rights reserved.

【 授权许可】

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