The EKRA Studies and the Formulation of the Swiss "Long term geological disposal" concept Reversibility of radioactive waste disposal was a demand of large parts of Swiss society in the 1990s. • A concept was developed by an interdisciplinary expert group, and introduced into the Swiss Law on Nuclear Energy in 2003, combining the safety requirements of finaldisposal, and the possibility of reversibility over the long term. • Key elements of reversibility are an appropriate layout of the repository and long-term monitoring of both the repository and the environment in a way that the decision of either sealing of the main repository or retrieval of waste is open to a future generation. • To be implemented, this concept needs a permanent public dialog on nuclear waste disposal and appropriate mechanisms of public involvement. Conservation of know-how has to be guaranteed by an open research and education programme.