Hydrogeological characterization of fractured rock for Sweden's nuclear waste storage

During the past 25 years Sweden has conducted research on the feasibility of storing spent nuclear fuel in an underground repository. A concept of engineered barriers surrounded by natural rock barriers was proposed as the main alternative for storage. The barrier concept is a necessary requirement for containment and delay of potential radioactive leakage. The process of finding a suitable site has now reached the stage where a generic site characterization programme has been set up. Once a potential site have been identified a site specific programme will be formulated. Efforts are focused to produce all necessary programme for the site characterization by the end of the year 2001. The characterization programme is based on a hydrogeological concept where the rock is divided into different hydraulically conducting features (e g fracture zones) hosted in rock possessing a background transmissivity. The paper presents possible strategies, methods and concepts to be employed within the hydrogeological site characterization program.