Journal article: Cigéo aims to store the most hazardous radioactive waste in a deep geological repository. The Socio-Economic Assessment (SEA) of the project is intended to analyse the gains and costs for the community, particularly in comparison with long-term storage, which will be the responsibility of future generations. This SEA has raised various methodological questions due to the duration of the project, the difficulties in monetising certain costs and benefits, the uncertainties about future societies and the choice of the discount rate. One conclusion is that Cigéo provides, through the safe burial of the waste, an ‘‘insurance benefit’’ in the face of a risk of degradation of future societies.