The design and installation of the PRACLAY In-site Experiment

For 40 years Belgium has been actively studying the long-term management of high-level and/or long-lived radioactive waste. A research programme was launched by the Belgian Nuclear Research Centre SCK•CEN at Mol in the early 1970s, and followed international recommendations to isolate radioactive waste from humans and the environment by means of geological disposal. This means that the waste is disposed of in a repository located in a geologically stable formation with appropriate characteristics. SCK•CEN chose to concentrate its efforts on investigating the poorly indurated Boom Clay layer because of the potentially favourable characteristics of this host rock. Because of the lack of experience in excavating underground facilities at a depth of some 200 metres in this type of clay, one of the main objectives of the initial research and development (R&D) programme was to assess and demonstrate the feasibility of building such a repository. This is why work on the underground research facility known as HADES (High-Activity Disposal Experimental Site) got under way in 1980 (Figure 1-1).