[en] Radioactive waste introduces a new time dimension in the field of risk management. This is why, for more than 10 years, there have been reflections on the societal and organisational mechanisms allowing a responsible management over the long term of the risk associated with radioactive waste. These reflections lead one to ask questions regarding interactions between what is at stake for societal and radiation protection criteria, demanding a multidisciplinary approach to the problem. Within the framework of the European project C.O.W.A.M. 2, dedicated to the improvement of governance of radioactive waste management in Europe, a working group involving experts, authorities, waste managers, locally elected representatives and N.G.O.s, discussed the stakes associated with the long term dimension. This article presents the main results of this working group, organised around four themes: meaning of the long term and what is at stake, the ethical dimension regarding long term issues, continuity and sustainability of the surveillance and control of radioactive waste facilities, effectiveness of financing schemes for the long term management of radioactive waste. (authors)