Gas-pressure-induced integrity of salt formations

Abstract

Abstract Besides other host rocks, rock salt formations are considered for the long-term storage of radioactive waste to exclude any threat to the biosphere. This means that the host-rock's integrity has to be guaranteed during construction, operation and in the post-closure phase of a repository. Gas-transport properties are key issues in the long-term assessment of the storage of high-level radioactive or toxic waste in salt formations. In this context, the impacts of disturbance induced by the excavation of the underground facilities and long-term effects during recompaction of the excavation disturbed zone (EDZ) are important items but in the past significant progress has been made. However, significant gas quantities may be generated in the long term (e.g. due to anaerobic corrosion, if humidity is present), resulting in a time-dependent pressure build-up that may affect the barrier integrity if the acting minimal stress is exceeded. The objective of this paper is to review the current understanding of the gas-transport properties in a salt environment at increased gas pressures associated with a radioactive waste repository. This knowledge has mainly been developed by laboratory work and fieldwork over the last decade.