Fabrication of UO2-BeO composite pellets with superior thermal conductivity based on multi-parameter theoretical analyses.

• Combing theoretical analyses and experimental investigations, the fabrication process of UO 2 -BeO was optimized. • Through this method, BeO density was effectively improved and UO 2 /BeO interfacial thermal resistance was decreased. • The thermal conductivity of UO 2 -BeO fabricated by this optimized method was improved by 89%. In this paper, the fabrication process of UO 2 -BeO composite pellets was optimized for improving the thermal conductivity based on multi-parameter theoretical analyses and experimental investigations. It was found that the density of BeO and UO 2 /BeO interfacial thermal resistance (ITR) are crucial parameters that affect the thermal conductivity of UO 2 -BeO. To effectively increase BeO density and decrease UO 2 /BeO ITR, the fabrication method of pressureless sintering with a spheroidizing process was proposed. Through this method, UO 2 -BeO composite with high thermal conductivity was obtained. 89.2% and 71.4% enhancements of the thermal conductivity over UO 2 were achieved at room temperature and 673 K, respectively. This enhancement is higher than all the reported results in the previous literatures that fabricated UO 2 -BeO using normal sintering temperatures (<2023 K). The results of finite element modelling showed that the centerline temperatures of our fabricated pellets in the reactor decreased remarkably compared with UO 2 fuel, which would significantly improve the safety of the reactor. [ABSTRACT FROM AUTHOR]