Technischer Bericht NTB 91-19

As a follow-up to the interim report of 1988 on the sediment study (NTB 88-25), which contained a general discussion of sediment options and relevant siting possibilities in Switzerland, this Technical Report provides a summary of investigations carried out by Nagra during the period 1988 to 1990 into sedimentary formations, namely the Lower Freshwater Molasse (Untere Süsswassermolasse) and the Opalinus Clay (Opalinus-Ton). Strategy guidelines and concepts for future investigations are also defined. The report consists of two parts: the first contains a summary overview based on the research reports which have been compiled since 1988, a description of the starting-point for the 1991 programme, together with the key questions which require to be answered, and a discussion of related procedures and investigation techniques. The second part (in the form of an appendix) gives a brief overview of the essential results from the different research reports.