The search for a site that could hold final repository for spent fuel presents itself as a great challenge to modern societies. Various different actors are part of this process and are communicating to solve the problem at hand. The communication includes the exchange of different kinds of knowledge concerning this complex endeavor. The thesis looks closely at the development of the Swedish radioactive waste management concept (KBS-3) and the interplay of different actors and their knowledge perspectives. In this respect the relevance of knowledge and non-knowledge are equally of interest.