大晶粒UO_(2)-SiC燃料芯块制备及高温氧化性能研究  

Study on preparation of large-grain UO_(2)-SiC fuel pellets and high-temperature oxidation resistance

作　　者：严超[1,2] 于小河 黄鹤 侯可可[1,2] 曹长青 林俊 朱智勇[1] YAN Chao;YU Xiaohe;HUANG He;HOU Keke;CAO Changqing;LIN Jun;ZHU Zhiyong(Shanghai Institute of Applied Physics,Chinese Academy of Sciences,Shanghai 201800,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院上海应用物理研究所,上海201800 [2]中国科学院大学,北京100049

出　　处：《核技术》2022年第4期81-87,共7页Nuclear Techniques

基　　金：中国科学院战略科技先导专项(No.XDA02030000、No.XDA02030200)资助。

摘　　要：通过在UO_(2)基体中添加第二相来提高燃料热导率是耐事故燃料的一个重要研究方向。该研究以大晶粒UO_(2)颗粒为原料,采用放电等离子烧结(Spark Plasma Sintering,SPS)工艺在较低烧结温度下获得高密度的大晶粒UO_(2)-SiC复合燃料芯块,对复合燃料芯块的性能进行了表征,并研究了其在空气环境中的抗高温氧化性能。结果显示:SPS低温烧结可有效避免高温下发生的UO_(2)-SiC界面反应,制备出的芯块密度>95%TD(理论密度)。与传统UO_(2)燃料芯块及常规UO_(2)粉末SPS烧结的UO_(2)-SiC芯块相比,大晶粒复合燃料芯块热导率明显提高。复合燃料芯块在高温氧化初期的氧化增重相较传统芯块明显减弱,但当氧化温度达到350℃时,SiC无法进一步阻止UO_(2)氧化。[Background] The Uranium dioxide(UO_(2)) is currently the most widely used nuclear fuel for commercial nuclear reactors. However, the Fukushima Daiichi nuclear disaster revealed the primary safety risks of this fuel in an accident, so various international programs were launched to develop accident tolerant fuel(ATF), a new generation of fuel system developed to enhance the capability of nuclear fuel assemblies in severe accidents.[Purpose] This study aims to improve the thermal conductivity of fuel pellets by adding a second material to the UO_(2)matrix, an important research direction for ATF. [Methods] First of all, large-grain UO_(2)particles were used as raw materials, and the high-density large grain UO_(2)-SiC composite fuel pellets were obtained by Spark Plasma Sintering(SPS) sintering process at lower sintering temperature. Then, the properties, such as microstructure and chemical composition, of the composite fuel pellets were characterized by using metallographic microscope(MM), scanning electron microscope(SEM), X-ray diffraction(XRD) and energy dispersive spectrometer(EDS). Finally, the high-temperature oxidation resistance in air environment was studied. [Results] The results show that the UO_(2)-Si C interfacial reaction can be avoided by the SPS sintering at lower temperature, and the density of the prepared pellets is more than 95% theoretical density(TD). Compared with traditional UO_(2)fuel pellets and SPS sintered UO_(2)-Si C pellets using conventional UO_(2)powders, the thermal conductivity of large-grain composite fuel pellets is significantly improved. Oxidation tests results indicate that the oxidation weight gain of the composite fuel pellets is significantly weaker than that of traditional pellets when the temperature is lower than 350 ℃. However, when the temperature reaches 350 ℃, the oxidation of UO_(2)cannot be further prevented by Si C. [Conclusions] This study provides reference for improving the thermal conductivity of UO_(2)matrix by adding a second phase with high thermal co

关 键 词：耐事故燃料 二氧化铀 复合燃料芯块 

分 类 号：TL99[核科学技术—核技术及应用]