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

The sealing performance of buffer material in a high-level waste repository depends largely upon the hydraulic conductivity, the swelling pressure, an d the dissolution of organic carbon in the buffer material. Temperature eff ects on these properties were evaluated. The hydraulic conductivity and the swelling pressure of compacted bentonite increase with increasing temperat ure, but the affect of temperature elevation is not large. The dissolution of organic carbon in bentonite also increases with increasing temperature, but the resultant aqueous concentrations of organic carbon in bentonite sus pensions are less than those of deep groundwater in granite. Therefore, the organic carbon dissolved from the bentonite will not cause a significant i ncrease in the organic carbon content of deep groundwater in the repository environment. Overall, temperature effects on the sealing performance of bu ffer material in a waste repository is not important, if the maximum temper ature is maintained below 100 degrees C. (C) 2000 Elsevier Science Ltd. All rights reserved.