High-burn-up structure evolution in polycrystalline UO_(2):Phase-field modeling investigation  

作　　者：Dan Sun Yanbo Jiang Chuanbao Tang Yong Xin Zhipeng Sun Wenbo Liu Yuanming Li 孙丹;姜彦博;唐传宝;辛勇;孙志鹏;柳文波;李垣明

机构地区：[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

出　　处：《Chinese Physics B》2025年第2期378-386,共9页中国物理B(英文版)

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.U20B2013 and 12205286);the National Key Research and Development Program of China(Grant No.2022YFB1902401)。

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.

关 键 词：high-burn-up structure phase field uranium dioxide gas bubble RECRYSTALLIZATION 

分 类 号：TG1[金属学及工艺—金属学]