In this paper, the fabrication process of UO₂-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 UO₂/BeO interfacial thermal resistance (ITR) are crucial parameters that affect the thermal conductivity of UO₂-BeO. To effectively increase BeO density and decrease UO₂/BeO ITR, the fabrication method of pressureless sintering with a spheroidizing process was proposed. Through this method, UO₂-BeO composite with high thermal conductivity was obtained. 89.2% and 71.4% enhancements of the thermal conductivity over UO₂ were achieved at room temperature and 673 K, respectively. This enhancement is higher than all the reported results in the previous literatures that fabricated UO₂-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 UO₂ fuel, which would significantly improve the safety of the reactor.

本文基于多参数理论分析和实验研究，对UO ₂ -BeO复合颗粒的制备工艺进行了优化，以提高其导热系数。发现BeO和UO ₂ / BeO界面热阻（ITR）的密度是影响UO ₂ -BeO的热导率的关键参数。为了有效地提高BeO的密度并降低UO ₂ / BeO ITR，提出了采用球化工艺进行无压烧结的制备方法。通过这种方法，获得了具有高导热率的UO ₂ -BeO复合材料。与UO _2相比，导热率提高了89.2％和71.4％分别在室温和673 K下达到。这种增强高于使用常规烧结温度（<2023 K）制造UO ₂ -BeO的先前文献中的所有报道结果。有限元建模的结果表明，与UO ₂燃料相比，反应堆中制造的颗粒的中心线温度显着降低，这将显着提高反应堆的安全性。