高庙子膨润土及其混合材料导热性能研究

导热性能是高放废物地质处置库缓冲/回填材料的重要性能之一。采用瞬变平面热源法,研究了我国高放废物地质处置首选缓冲/回填材料高庙子膨润土,及以其为主料,添加不同含量石英砂、北山花岗岩碎屑组成的混合材料的导热性能。分析了添加剂种类和含量、干密度、饱和度等因素对导热系数的影响。研究结果表明:高庙子膨润土及其混合材料的导热系数、热扩散系数都随干密度和含水量的增大而增大;石英砂、北山花岗岩碎屑能够不同程度提高膨润土的导热系数,石英砂的作用优于北山花岗岩碎屑;饱和度对添加剂发挥其提高缓冲/回填材料导热性能的作用影响明显,饱和度越高,添加剂的作用越显著。

Thermal Property of GMZ Bentonite and Bentonite-based Mixtures

Thermal property is one of the most important characters of buffer/backfill material for high-level radioactive waste (HLW) disposal repository. Transient plane source method was employed to measure the thermal properties of GMZ bentonite and bentonite-based mixtures, which is considered to be the potential choice as buffer/backfill material in the Chinese program of HLW disposal. Silica sand and crushed Beishan granite were selected as an additive to enhance the thermal properties of GMZ bentonite. The effect of type and mass fraction of additives, dry density, degree of saturation, etc. on the thermal conductivity of GMZ bentonite and bentonite-based mixtures were analyzed. Test results show that the thermal conductivity and thermal diffusivity of GMZ bentonite and bentonite-based mixtures increase with dry density and water content. Thermal properties of GMZ bentonite could be improved by the addition of silica sand and crushed Beishan granite, and silica sand was more effective than crushed Beishan granite. Degree of saturation had a significant influence on the effect of additives. The improvement of the thermal conductivity of mixtures by additives was more obvious when the degree of saturation was higher.