Assessment of Tectonic Effects on Radwaste Isolation in Underground Repositories

Underground repositories for radwaste must secure reliable isolation from the biosphere for several thousand years. The possibility of tectonic disturbances during such a long period of time becomes real even in seismically calm regions. The influence of tectonic disturbances, occurring after a repository is sealed, on the reliability of the isolation of radwaste disposed in this repository was analyzed. The most dangerous case of a tectonic fault passing through the repository itself is considered. The analysis was based on a two-dimensional model of the flow of groundwater and the transport of the constituent radionuclides of the waste. It is noted that the degree to which the fault affects the safety of the repository increases with decreasing half-life of the radionuclides.