Mesoscale Benchmark Demonstration Problem 1: Mesoscale Simulations of Intra-granular Fission Gas Bubbles in UO2 under Post-irradiation Thermal Annealing

Li, Yulan ; Hu, Shenyang Y. ; Montgomery, Robert ; Gao, Fei ; Sun, Xin ; Tonks, Michael ; Biner, Bullent ; Millet, Paul ; Tikare, Veena ; Radhakrishnan, Balasubramaniam ; Andersson , David

关键词: ANNEALING;    ATOMS;    BENCHMARKS;    BUBBLE GROWTH;    BUBBLES;    DEFECTS;    DIFFUSION;    EFFICIENCY;    FISSION;    FREE ENERGY;    KINETICS;    MICROSTRUCTURE;    MONTE CARLO METHOD;    VACANCIES Mesoscale benchmark;    Phase-field approach;    Kinetic Monte Carlo approach;    Potts Model;    Fission gas bubbles;    Uranium dioxide;    Post-irradiation thermal annealing.;   

DOI  :  10.2172/1049667
RP-ID  :  PNNL-21295
PID  :  OSTI ID: 1049667
Others  :  Other: NT0108060
Others  :  TRN: US1204568

学科分类：社会科学、人文和艺术（综合）

美国|英语

来源: SciTech Connect

【 摘 要 】

A study was conducted to evaluate the capabilities of different numerical methods used to represent microstructure behavior at the mesoscale for irradiated material using an idealized benchmark problem. The purpose of the mesoscale benchmark problem was to provide a common basis to assess several mesoscale methods with the objective of identifying the strengths and areas of improvement in the predictive modeling of microstructure evolution. In this work, mesoscale models (phase-field, Potts, and kinetic Monte Carlo) developed by PNNL, INL, SNL, and ORNL were used to calculate the evolution kinetics of intra-granular fission gas bubbles in UO2 fuel under post-irradiation thermal annealing conditions. The benchmark problem was constructed to include important microstructural evolution mechanisms on the kinetics of intra-granular fission gas bubble behavior such as the atomic diffusion of Xe atoms, U vacancies, and O vacancies, the effect of vacancy capture and emission from defects, and the elastic interaction of non-equilibrium gas bubbles. An idealized set of assumptions was imposed on the benchmark problem to simplify the mechanisms considered. The capability and numerical efficiency of different models are compared against selected experimental and simulation results. These comparisons find that the phase-field methods, by the nature of the free energy formulation, are able to represent a larger subset of the mechanisms influencing the intra-granular bubble growth and coarsening mechanisms in the idealized benchmark problem as compared to the Potts and kinetic Monte Carlo methods. It is recognized that the mesoscale benchmark problem as formulated does not specifically highlight the strengths of the discrete particle modeling used in the Potts and kinetic Monte Carlo methods. Future efforts are recommended to construct increasingly more complex mesoscale benchmark problems to further verify and validate the predictive capabilities of the mesoscale modeling methods used in this study.