无损检测技术在缓冲材料砌块压制质量检测中的应用

Application of Nondestructive Testing Technology in Quality Detection of Buffer Material Block Compaction

缓冲材料是高放废物地质处置库的最后一道人工屏障,通常是以高压实预制砌块的形式堆砌在废物罐周围,砌块压制质量将极大地影响其工程性质。以缓冲材料压实砌块为研究对象,使用超声波测试、热传导测试和激光三维扫描3种无损检测方法,对不同尺寸和干密度的小型试样、大型砌块的不同位置进行了质量检测和分析。结果表明:小型试样的纵波波速随干密度和含水率的增大而增大,纵波波速与干密度呈近似线性关系,大型砌块的纵波波速随压制面距离的增加而减小;大型砌块顶面各个位置的导热系数变化不明显,砌块高度方向导热系数随压制面距离的增加而减小,且与纵波波速测试结果具有一致性。激光三维扫描技术可以快速、全面获取砌块的线、面和体等各种数据参数。因此,超声波测试、热传导测试和激光三维扫描可为缓冲材料大型砌块制备工艺的优化和砌块压制均匀性的评价提供重要的参数依据和技术支撑。

Buffer material is the last engineering barrier material of high-level radioactive waste geological repository.The canisters are usually surrounded by the buffer material in the form of compacted blocks.The quality of compacted blocks will greatly affect its engineering properties.In this paper,three non-destructive testing methods,ultrasonic testing,heat conduction testing and threedimensional laser scanning,were used to detect and analyze the quality of independent small samples and small specimens from different positions of large compacted buffer blocks with different sizes and dry densities.The results show that for independent small samples,the longitudinal wave velocity increases with the increase of dry density and water content,and the longitudinal wave velocity is approximately linear with the dry density.The longitudinal wave velocity of large blocks decreases with the increase of the distance of the pressing surface.The thermal conductivity of each position on the top surface of the block does not change significantly,and the thermal conductivity in the height direction decreases with the increase of the distance from the pressing surface,which is consistent with the longitudinal wave velocity test results.The laser three-dimensional scanning technology can quickly and comprehensively obtain various data parameters related to the line,surface and body of the block.The ultrasonic test,heat conduction test and laser three-dimensional scanning test can provide basic parameters and technical methods,which are needed in the optimization of manufacturing process and in the homogeneity detection of compacted buffer block.