Application of local bentonite as buffer and backfill material in low-level radioactive waste disposal facility

摘要

Bentonite has been extensively used as buffer and backfill materials in artificial engineering barriers system in radioactive waste (Radwatse) disposal facility. Due to the low hydraulic conductivity of bentonite, the hazardous radionuclide in the radwastes could be retarded for hundred or thousand years, which ensures radioactivity of radionuclide degrades to a relatively low level. It provides a safe solution for the disposal of poisonous radwastes. Bentonite material used in disposal facilities could be imported or produced locally. This study aims to evaluate the feasibility of adopting bentonite mined in Taiwan. In this work, bentonite of Wyoming imported from the USA and Zhishin clay produced in Taiwan were selected. The buffer and backfill material were made by mixing bentonite with different aggregates. Tested samples was compacted into size of Φ50 mm × h20mm under different compaction energies. Soil properties tests, swelling tests, and hydraulic conductivity tests were performed to evaluate the performance of buffer and backfill materials. Based on the test result, the feasibility of using local bentonite as buffer and backfill materials was evaluated in this study. The results showed that the local bentonite was only suitable for backfill materials.