Investigations of site suitability for the final disposal of low- and intermediate-level radioactive wastes. Status report of phase I investigations for the feasible Piz Pian Grand site (communities Mesocco and Rossa, GR)

On 30th September 1985, the Federal Government granted Nagra permission to investigate the three potential sites Bois de la Glaive, Oberbauenstock and Piz Pian Grand with a view to assessing their suitability for disposal of low- and intermediate-level radioactive waste. This report summarises the investigations carried out at Piz Pian Grand, together with the results obtained during the course of the programme. The first chapter discusses the key aspects of planning and performing the work and outlines the general objectives of the research. It also gives a brief time-schedule for the investigations. The results of the geological investigations are detailed in chapter 2. Starting with an overview of existing data on the area, the report goes on to give as comprehensive as possible a picture of the geological and hydrogeological conditions found to exist on analysis of the investigation results. The modelling studies and a provisional engineering concept for a potential repository for low-and intermediate-level waste are described in chapter 3. The fourth and final chapter summarises all the aforementioned results. It can be concluded that there are no grounds for ruling out Piz Pian Grand as a potential site. The data required for a more detailed assessment of the suitability of the area for low- and intermediate-level waste disposal can only be obtained by constructing an exploratory drift. 37 refs., 34 figs., 14 tabs