UN-U_(3)Si_(2)复合燃料的多尺度蠕变行为研究  

Research on multi-scale creep behaviors of UN-U_(3)Si_(2) composite fuels

作　　者：杨青峰 谢哲骁 陈平[1] 张静 高士鑫 丁国琛 周毅[1] 尹春雨[1] 丁淑蓉 何梁 孙丹 YANG Qingfeng;XIE Zhexiao;CHEN Ping;ZHANG Jing;GAO Shixin;DING Guochen;ZHOU Yi;YIN Chunyu;DING Shurong;HE Liang;SUN Dan(Science and Technology on Reactor System Design Technology Laboratory,Nuclear Power Institute of China,Chengdu 610213,China;Institute of Mechanics and Computational Engineering,Department of Aeronautics and Astronautics,Fudan University,Shanghai 200433,China)

机构地区：[1]中国核动力研究设计院核反应堆系统设计技术重点实验室,成都610213 [2]复旦大学航空航天系力学与工程仿真研究所,上海200433

出　　处：《核技术》2022年第12期57-64,共8页Nuclear Techniques

基　　金：国家重点研发计划(No.2019YFB1901000);国家自然科学基金重点项目(No.12132005,No.12135008)资助。

摘　　要：UN-U_(3)Si_(2)复合燃料在未来先进耐事故燃料元件中具有良好的发展前景,其堆内运行所产生的辐照蠕变及热蠕变对元件的辐照热力耦合行为及安全性会产生重要影响。基于文献中的宏观蠕变实验结果,分别针对UN和U_(3)Si_(2)多晶燃料主控的蠕变机制进行分析,通过拟合得到考虑空位扩散和位错运动机制的蠕变率模型,该模型的预测结果与实验结果吻合很好,证明了模型的合理性;基于均匀化理论建立了去除辐照肿胀效应后UN-U_(3)Si_(2)复合燃料宏观蠕变与各组分贡献的关联模型。基于文献上的复合燃料金相结构图,发展了随机建模方法,对UN-U_(3)Si_(2)复合燃料(20%U_(3)Si_(2))辐照条件下单轴拉伸蠕变实验进行了数值模拟,获得了组分材料对复合燃料宏观等效蠕变所产生的贡献,并分析了蠕变机制。分析结果表明:UN和U_(3)Si_(2)存在的辐照肿胀差异,导致复合燃料内部产生了强烈的力学相互作用;在裂变密度达到4.32×10^(27)fissions·m^(−3)时,颗粒与基体相界面处的最大von Mises应力约为外部施加的均布拉力的6倍,但由于存在低应力区,两种材料的辐照肿胀对复合燃料宏观等效蠕变应变的影响可以忽略不计。[Background]UN-U_(3)Si_(2) composite fuels have a promising prospect in advanced future accident tolerant fuel elements.Its irradiation creep and thermal creep caused by in-reactor operation have an important influence on the irradiation-induced thermo-mechanical coupling behavior and safety of the fuel elements.[Purpose]This study aims to develop a stochastic modeling method according to the metallographic structure of composite fuel and numerical simulation of the uniaxial tensile creep test of the UN-U_(3)Si_(2) composite fuel(20% U_(3)Si_(2)).[Methods]Based on the data of creep experiments from literatures,the dominated creep mechanisms of UN and U_(3)Si_(2) polycrystalline fuels were analyzed,and their creep rate models considering vacancy diffusion and dislocation motion mechanisms were obtained by curve fitting.Then,the correlation model between the macroscopic creep of composite fuel and the contribution of each component was established on the basis of the homogenization theory and the removal of irradiation swelling effect.Finally,based on the metallographic structure diagram of composite fuels in the literatures,stochastic modeling method was developed and applied to the numerical simulation of the uniaxial tensile creep test of the UN-U_(3)Si_(2) composite fuel(20% U_(3)Si_(2)).[Results]The model predictions of UN and U_(3)Si_(2)creep rates are in good agreement with the experimental results,validating the effectiveness of the model.The contribution of the component fuels to the macroscopic equivalent creep of the composite fuel is obtained by analysis of the underlying creep mechanism.When the fission density reaches 4.32×10^(27) fissions·m^(−3),the maximum von Mises stress at the interface between particles and matrix is about 6 times of the homogeneous tensile stress applied externally.[Conclusions]The research results indicate that the difference in the irradiation swelling of UN and U_(3)Si_(2) will result in the strong internal mechanical interaction in the composite fuel whilst the existenc

关 键 词：UN-U_(3)Si_(2) 蠕变机制 辐照肿胀 均匀化理论 宏观等效蠕变 

分 类 号：TB321[一般工业技术—材料科学与工程]