Simulations of Xe and U diffusion in UO2

Andersson, Anders D.¹  Vyas, Shyam¹  Tonks, Michael R.²  Casillas, Luis¹  Uberuaga, Blas P.¹  Millett, Paul² 

[1]Los Alamos National Laboratory

[2]Idaho National Laboratory

关键词: ATOMS;    DEFECTS;    DIFFUSION;    FUNCTIONALS;    GRAIN BOUNDARIES;    IRRADIATION;    SEGREGATION;    THERMODYNAMICS;    URANIUM;    VACANCIES;    XENON;   

DOI  :  10.2172/1050508
RP-ID  :  LA-UR-12-24591
PID  :  OSTI ID: 1050508
Others  :  TRN: US201218%%1032

学科分类：材料科学（综合）

美国|英语

来源: SciTech Connect

【 摘 要 】

Diffusion of xenon (Xe) and uranium (U) in UO{sub 2} is controlled by vacancy mechanisms and under irradiation the formation of mobile vacancy clusters is important. Based on the vacancy and cluster diffusion mechanisms established from density functional theory (DFT) calculations, we derive continuum thermodynamic and diffusion models for Xe and U in UO{sub 2}. In order to capture the effects of irradiation, vacancies (Va) are explicitly coupled to the Xe and U dynamics. Segregation of defects to grain boundaries in UO{sub 2} is described by combining the bulk diffusion model with models of the interaction between Xe atoms and vacancies with grain boundaries, which were derived from atomistic calculations. The diffusion and segregation models were implemented in the MOOSE-Bison-Marmot (MBM) finite element (FEM) framework and the Xe/U redistribution was simulated for a few simple microstructures.