Influence of temperature elevation on the sealing performance of a potential buffer material for a high-level radioactive waste repository

The sealing performance of bu€er material in a high-level waste repository depends largely upon the hydraulic conductivity, the swelling pressure, and the dissolution of organic carbon in the bu€er material. Temperature e€ects on these properties were evaluated. The hydraulic conductivity and the swelling pressure of compacted bentonite increase with increasing tem- perature, but the e€ect of temperature elevation is not large. The dissolution of organic car- bon in bentonite also increases with increasing temperature, but the resultant aqueous concentrations of organic carbon in bentonite suspensions are less than those of deep groundwater in granite. Therefore, the organic carbon dissolved from the bentonite will not cause a signi®cant increase in the organic carbon content of deep groundwater in the reposi- tory environment. Overall, temperature e€ects on the sealing performance of bu€er material in a waste repository is not important, if the maximum temperature is maintained below 100 C