Thermal conductivity of UO2 pellets enhanced by a semi-continuous structure of Ti3SiC2

The current distribution structure of the thermal conductivity (TC) enhancements in UO2 matrix can be divided into three categories: dispersed structure, continuous structure and oriented structure. This paper develops a new semi-continuous structure to improve the TC of UO2. Ti3SiC2 is selected as the enhancement in this paper due to its excellent irradiation resistance and high TC at elevated temperature. The semi-continuous structure of Ti3SiC2 is formed through a simple centrifugal spheroidization of UO2 and a followed powder mixing process. Both the theoretical prediction and experimental results indicate the semi-continuous structure has a close TC enhancing efficiency to the continuous structure. Meanwhile, the semi-continuous structure has the advantages of simplifying the fabrication process and can be applied to more kinds of enhancements compared to the continuous structure. The TC of Ti3SiC2/UO2 is remarkably improved at elevated temperature compared with pure UO2, which is beneficial to the fuel safety.