Thermal conductivity of buffer material is crucial for the design and performance assessment of high-level radioactive waste (HLW) repository. Large amount of decay heat will increase the maximum temperature in bentonite buffer, which threatens the safety of HLW repository. One possible method to relieve such problem is adding graphite to bentonite for increasing its thermal conductivity. Therefore, the thermal conductivities of a bentonite with different graphite contents were measured by the heat flow meter method and the results showed that the thermal conductivity was a function of graphite content, water content and void ratio, while the temperature had ignorable influence for dry bentonite or bentonite-graphite mixture. The volume fraction of air and degree of saturation were strongly linear with the thermal conductivity. Based on experimental data, the Cote-Konrad model, geometric mean model and two Maxwell-like models were introduced and improved, and the suggested predictive methods proved to be effective by literature data.

缓冲材料的热导率对于高放废物（HLW）储存库的设计和性能评估至关重要。大量的衰变热会增加膨润土缓冲液的最高温度，从而威胁到高放废物处置库的安全。解决该问题的一种可能的方法是将石墨添加到膨润土中以增加其热导率。因此，用热流量计方法测量了不同石墨含量的膨润土的导热系数，结果表明，导热系数是石墨含量，水含量和空隙率的函数，而温度对干膨润土的影响可忽略不计。或膨润土-石墨混合物。空气的体积分数和饱和度与热导率呈强线性关系。