SiC复合包壳在辐照后LOCA工况下的热力耦合行为及其影响机制研究  

On the Thermo⁃Mechanical Coupling Behaviors and Influencing Mechanisms of SiC Composite Cladding Tubes Under Post⁃Irradiation LOCA Conditions

作　　者：王金强 陈露宁 卢志威 王诗槐 任啟森 薛佳祥 丁淑蓉 WANG Jinqiang;CHEN Luning;LU Zhiwei;WANG Shihuai;REN Qisen;XUE Jiaxiang;DING Shurong(Institute of Mechanics and Computational Engineering,Department of Aeronautics and Astronautics,Fudan University,Shanghai 200433,China;China Nuclear Power Technology Research Institute,Shenzhen 518028,Guangdong,China)

机构地区：[1]复旦大学航空航天系,力学与工程仿真研究所,上海200433 [2]中广核研究院有限公司,广东深圳518028

出　　处：《力学季刊》2024年第3期625-637,共13页Chinese Quarterly of Mechanics

基　　金：国家自然科学基金(12132005,12135008,12102094)。

摘　　要：碳化硅(SiC)复合包壳的热-力学性能和抗辐照性能较强,是一种优异的轻水堆事故容错燃料包壳,其结构完整性对反应堆安全运行至关重要.本文综合考虑各层材料的辐照效应,开展了SiC复合包壳在轻水反应堆稳态运行1146天后发生失水事故(Loss of Coolant Accident,LOCA)期间的热-力耦合行为数值模拟,获得了CVD-SiC单质层的第一主应力分布和演化规律,并对应力演化的影响机制开展了分析.结果表明:LOCA期间内部CVD-SiC单质层的最大拉应力先迅速增加,后缓慢增加,存在开裂的风险;包壳外压降低是内部CVD-SiC单质层最大拉应力及复合材料层损伤因子快速增加的重要原因;内压随着温度的升高而增大,是内部CVD-SiC单质层最大拉应力及复合材料层损伤因子继续增加到峰值的原因;复合包壳管在稳态运行阶段存在较大的径向温差,由于LOCA初期温差的降低引起的热应力对内部CVD-SiC单质层的最大拉应力也产生了显著的影响,有望通过提高碳化硅纤维增强复合材料的热导率来降低复合包壳管的失效风险.The SiC composite cladding,composed of the monolithic SiC and the SiCf/SiC composite,has emerged as a leading structure for accident tolerant fuel cladding due to its exceptional thermodynamic properties and radiation resistance.Ensuring the structural integrity of the SiC composite cladding is crucial for reactor safety.In this study,the irradiation effects of monolithic SiC and SiC f/SiC composite were considered.Numerical simulation of the thermo-mechanical coupling behaviors of the SiC triplex composite cladding during a loss of coolant accident(LOCA)of the light water reactor after 1146 days of safe operation was carried out.The distribution and evolution of the first principal stress of the monolithic SiC was obtained and the influencing factors were analyzed.The results show that in the early stage of LOCA,the first principal stress of the monolithic SiC increases rapidly,then slowly increases and finally decreases,with a risk of cracking.The decrease in coolant pressure is an important reason for the initial increase of stress of the monolithic SiC,while the increase in internal pressure and the damage of the SiC f/SiC composite,are the dominated reasons for the later increase of the first principal stress of the interior monolithic SiC layer.In the steady-state condition,there is a significant temperature difference along the radial direction of the cladding.The thermal stress caused by the decrease in the temperature difference in the early stage of LOCA also has a significant impact on the maximum stress of the monolithic SiC.It is feasible to reduce the failure risk of the SiC composite cladding by improving the thermal conductivity of the SiC f/SiC composite.

关 键 词：失水事故 SiC复合包壳 热-力耦合 辐照效应 数值模拟 

分 类 号：TL352.1[核科学技术—核技术及应用]