Sources of errors and uncertainty in the prediction of the geologic behaviour of a nuclear waste repository

Groundwater models have now been used for more than 20 years to predict the behaviour of aquifer systems; only recently, and in some cases, however, have these predictions been compared with what actually happened in the system. A few of these comparisons are summarized with the objective of emphasizing the conclusions that can be drawn from them for waste disposal purposes, i.e. to point out the sources of the errors that make the predictions differ from reality in groundwater flow analysis. Special mention is made of the behaviour of low-permeability media. 14 refs