The international relevance of learning from nuclear waste management in Sweden cannot be underestimated as the planning process for the final disposal of spent nuclear fuel in Sweden has been underway for more than thirty years. During this time the same types of actors—private, public, and NGO representatives—and even the same individuals have interacted with each other throughout. Based on a review of the implementer’s Research, Development and Demonstration programmes (RD& Ds) of methods for the management and disposal of nuclear waste and interviews with representatives of the implementer, regulator, and NGOs, this paper analyses the outcomes of these long-term interactions. It then discusses the potentially serious problems this creates in relation to knowledge production in the planning and environmental impact assessment process and problems now the regulator is set to review the final application. The tendency of the values and priorities of implementer and regulator to converge over time, due to sustained social interaction, is a new phenomenon, which could not only impede the safety of nuclear waste management, but also risks occurring in other countries embarking on similar long-term processes.