Sustainability has over the last decade gained great weight in decision-making. Society is struggling with the question of how to introduce value-laden sustainable development principles into practice. Recently a framework for sustainability assessment has been put forward. Application of this framework to the Belgian proposal for high-level radioactive waste management allows us to get an overview of forces and problems that obstruct the development of the programme and to formulate clear recommendations. Pluralism, flexibility and social learning emerge as key concepts for a sustainable management of high-level waste, pointing at the importance of retrievability for future concepts.