A strong social and technical divide plays a significant part in the predominant understanding of technological innovation in modern society, codifying the relationship between society and technology in terms of technological supremacy embedded in a more or less supportive social context. As such, this divide also influences the social sciences’ understanding of technological development, which often blackboxes the working of technological objects, allowing the delegation of responsibility almost entirely to technical experts. We call this separation of the technical and the social the first wave in understanding technological innovation. In contrast, the academic field of Science and Technology Studies (STS) has the ambition to overcome this divide. This second wave of understanding technological innovation is about focusing on the strong and continuously entwined relationships between the social and the technical, that is, sociotechnical combinations. While the second wave is correct in stating that the social and the technical are entangled, with the technical never being ‘purely technical’, the first wave is also correct insofar as some issues are more technical than others, that is, a technical problematisation is different to a social problematisation of the same issue. In this report we discuss the limitations of both of these understandings, proposing a third wave called problematisation: the process of defining what is a problem in a given situation, identifying the causes of this problem and proposing ways to resolve it. In order to democratise technological innovation, social scientists should be more focused on how technical problematisation occurs. To focus on divisions or combinations in this regard is of no help. The concept of technical problematisation aims to make technical democracy real – to make public participation and social science research related to technical activities more meaningful. The three waves are illustrated by examples from European radioactive waste management. The nuclear field is one where the social and the technical dimensions have traditionally been most distinctly separated, where the search for ‘pure’ and definitive technical solutions that can guarantee safety for thousands of years has been the ultimate goal and delegated to technical experts alone. However, during recent decades there has been a push for increasing participation and more democracy in decision- making, with much experimentation taking place. However, the only way these activities will successfully support the democratising process is for them to be integrated into the technical problematisation of proposed radwaste solutions.