Thorium-uranium oxide pellets with high densities were prepared at the Canadian Nuclear Laboratories (CNL) by co-milling, pressing, and sintering at 2023 K, with UO₂ mass contents of 0, 1.5, 3, 8, 13, 30, 60 and 100%. At the Joint Research Centre, Karlsruhe (JRC-Karlsruhe), thorium-uranium oxide pellets were prepared using the spark plasma sintering (SPS) technique with 79 and 93 wt. % UO₂. The thermal diffusivity of (Th_1-xU_x)O₂ (0 ≤ x ≤ 1) was measured at CNL and at JRC-Karlsruhe using the laser flash technique. ThO₂ and (Th,U)O₂ with 1.5, 3, 8 and 13 wt. % UO₂ were found to be semi-transparent to the infrared wavelength of the laser and were coated with graphite for the thermal diffusivity measurements. This semi-transparency decreased with the addition of UO₂ and was lost at about 30 wt. % of UO₂ in ThO₂. The thermal conductivity was deduced using the measured density and literature data for the specific heat capacity. The thermal conductivity for ThO₂ is significantly higher than for UO₂. The thermal conductivity of (Th,U)O₂ decreases rapidly with increasing UO₂ content, and for UO₂ contents of 60% and higher, the conductivity of the thorium-uranium oxide fuel is close to UO₂. As the mass difference between the Th and U atoms is small, the thermal conductivity decrease is attributed to the phonon scattering enhanced by lattice strain due to the introduction of uranium in ThO₂ lattice. The new results were compared to the data available in the literature and were evaluated using the classical phonon transport model for oxide systems.

通过在2023 K下共同研磨，压制和烧结，在加拿大核实验室（CNL）制备高密度的-铀氧化物颗粒，UO _2的质量含量为0、1.5、3、8、13、30、60和100％。在卡尔斯鲁厄（JRC-Karlsruhe）联合研究中心，使用火花等离子烧结（SPS）技术以79和93 wt。％的重量制备了-铀氧化物颗粒。％UO ₂。（Th _1-x U _x）O ₂（0≤x≤1 ）的热扩散率是使用激光闪光技术在CNL和JRC-Karlsruhe处测得的。具有1.5、3、8和13重量％的ThO ₂和（Th，U）O ₂。UO _2的百分比被发现对激光的红外波长是半透明的，并涂有石墨以进行热扩散率测量。随着UO ₂的添加，该半透明性降低，并且在约30wt。％时丧失。UO ₂在ThO _2中的百分比。使用测得的密度和比热容的文献数据推导热导率。ThO ₂的导热系数明显高于UO ₂的导热系数。（Th，U）O ₂的热导率随UO ₂含量的增加而迅速降低，并且当UO ₂含量为60％或更高时，or-铀氧化物燃料的电导率接近UO₂。当Th和U原子之间的质量差较小时，热导率的下降归因于由于铀在ThO ₂晶格中的引入而使晶格应变增强了声子散射。将新结果与文献中提供的数据进行比较，并使用经典的声子输运模型对氧化物系统进行评估。