中国物理B ›› 2025, Vol. 34 ›› Issue (2): 26102-026102.doi: 10.1088/1674-1056/ad9c42
High-burn-up structure evolution in polycrystalline UO2: Phase-field modeling investigation
Dan Sun(孙丹)1,†, Yanbo Jiang(姜彦博)2,†, Chuanbao Tang(唐传宝)1, Yong Xin(辛勇)1, Zhipeng Sun(孙志鹏)1, Wenbo Liu(柳文波)2, and Yuanming Li(李垣明)1,‡
- 1 National Key Laboratory of Nuclear Reactor Technology, Nuclear Power Institute of China, Chengdu 610213, China;
2 School of Nuclear Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China
High-burn-up structure evolution in polycrystalline UO2: Phase-field modeling investigation
Dan Sun(孙丹)1,†, Yanbo Jiang(姜彦博)2,†, Chuanbao Tang(唐传宝)1, Yong Xin(辛勇)1, Zhipeng Sun(孙志鹏)1, Wenbo Liu(柳文波)2, and Yuanming Li(李垣明)1,‡
- 1 National Key Laboratory of Nuclear Reactor Technology, Nuclear Power Institute of China, Chengdu 610213, China;
2 School of Nuclear Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China
摘要： Understanding the evolution of microstructures in nuclear fuels under high-burn-up conditions is critical for extending fuel refueling cycles and enhancing nuclear reactor safety. In this study, a phase-field model is proposed to examine the evolution of high-burn-up structures in polycrystalline UO$_{2}$. The formation and growth of recrystallized grains were initially investigated. It was demonstrated that recrystallization kinetics adhere to the Kolmogorov-Johnson-Mehl-Avrami (KJMA) equation, and that recrystallization represents a process of free-energy reduction. Subsequently, the microstructural evolution in UO$_{2}$ was analyzed as the burn up increased. Gas bubbles acted as additional nucleation sites, thereby augmenting the recrystallization kinetics, whereas the presence of recrystallized grains accelerated bubble growth by increasing the number of grain boundaries. The observed variations in the recrystallization kinetics and porosity with burn-up closely align with experimental findings. Furthermore, the influence of grain size on microstructure evolution was investigated. Larger grain sizes were found to decrease porosity and the occurrence of high-burn-up structures.
中图分类号: (Theory and models of radiation effects)
- 61.80.Az