The fluids in salt have been used as sources of information on the geological events leading to the formation of the enclosing salt beds, and the subsequent changes to which these beds have been exposed. In recent years, however, consideration of salt beds or domes as possible sites for long-term nuclear waste repositories has added new significance to the study of such fluids.
This paper reviews the current status of the study of the types of fluid present in salt, their origin and evolution, and their significance to understanding the geological processes that have occurred. These studies are pertinent to the engineering design of a nuclear waste storage site in salt in that they tell us what might happen in the future. The fluids in salt also introduce problems in the engineering design of a safe nuclear waste installation that must be carefully evaluated at each suggested site.