High performance cement-based grouts for use in a nuclear waste disposal facility

Abstract National and international agencies have identified cement-based materials as prime candidates for sealing vaults in which nuclear fuel wastes will be isolated from the biota. Insufficient information is currently available to allow for reasonable analysis of the long-term performance of these sealing materials in a vault. This paper details some of the major findings from combined laboratory and modelling research programs intended to provide the necessary information for a specially developed high-performance cement-grout. The results indicate that acceptable performance is likely for at least thousands of years and probably for much longer periods. The materials, which have been proven to be effective in field applications, are shown to be virtually impermeable and highly leach resistant under vault conditions. Special plasticizing additives used in the material formulation enhance physical characteristics without detriment to chemical resilience. Neither modelling nor laboratory testing has as yet provided for definitive assessment of longevity. However, none of the results of the studies, to date, have contra-indicated the use of high-performance cement-based grouts in vault sealing applications.