Manufacturing method for meter-scale buffer material blocks

In the high-level radioactive waste (HLW) repository, the canisters are usually surrounded by buffer materials in the form of blocks. The manufacturing method for large-scale buffer blocks is regarded as a difficult problem to be solved in the in-situ tests and the safety operation of HLW repository. The manufacturing of large-scale buffer blocks with Gaomiaozi (GMZ) bentonite and the physical properties of blocks are studied. The buffer blocks are compacted under three loading rates and holding time, and the effects of the loading rates and holding time on the integrity and homogeneity of the buffer blocks are analyzed. By cutting and coring different sections of the buffer blocks, it is found that the dispersion of physical properties such as dry density and water content is small, indicating that the buffer blocks are quite homogeneous. The key manufacturing technology of large-scale buffer blocks is established by considering the integrity, homogeneity and productivity of the blocks comprehensively. Then, the meter-scale buffer blocks which are suitable for the engineering conditions are well produced. The research results may provide a technical support and scientific basis for the in-situ tests of buffer materials in the underground research laboratory.