MARMOT simulations of Xe segregation to grain boundaries in UO2

Andersson, Anders D.¹  Tonks, Michael²  Casillas, Luis¹  Millett, Paul²  Vyas, Shyam¹  Uberuaga, Blas P.¹  Nerikar, Pankaj³ 

[1]Los Alamos National Laboratory

[2]Idaho National Laboratory

[3]IBM

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

DOI  :  10.2172/1044127
RP-ID  :  LA-UR-12-22368
PID  :  OSTI ID: 1044127
Others  :  TRN: US201214%%640

学科分类：材料科学（综合）

美国|英语

来源: SciTech Connect

【 摘 要 】

Diffusion of Xe and U in UO{sub 2} is controlled by vacancy mechanisms and under irradiation the formation of mobile vacancy clusters is important. We derive continuum thermodynamic and diffusion models for Xe and U in UO{sub 2} based on the vacancy and cluster diffusion mechanisms established from recent density functional theory (DFT) calculations. Segregation of defects to grain boundaries in UO{sub 2} is described by combining the diffusion model with models of the interaction between Xe atoms and vacancies with grain boundaries derived from separate atomistic calculations. The diffusion and segregation models are implemented in the MOOSE/MARMOT (MBM) finite element (FEM) framework and we simulate Xe redistribution for a few simple microstructures. In this report we focus on segregation to grain boundaries. The U or vacancy diffusion model as well as the coupled diffusion of vacancies and Xe have also been implemented, but results are not included in this report.