Abstract
The design requirements for the engineered barrier system (EBS) and the disposal facility in general were clarified based on currently available technologies. Realistic and reliable data and analysis techniques were used to derive specifications for the EBS and the other components of the disposal facility, also taking economic aspects into consideration.
The practical feasibility of designing and emplacing the EBS and constructing the disposal facility was examined for a wide range of physical rock properties. The impact on barrier performance of different materials and overpack and buffer dimensions was investigated and the results of preliminary calculations were used to modify the design specifications. Bentonite mixed with quartz sand was selected as the buffer material, which could bring about a reduction in costs without compromising performance.
The mechanical stability of tunnels was investigated based on data obtained from relevant geological environments. Rough estimates were then made of the depth range in which construction of the disposal facility is feasible. In addition, a design concept for efficient emplacement of the vitrified waste and layout of the tunnels was developed based on thermal analyses. It was shown that construction of the disposal system, emplacement of the waste forms and backfilling of the tunnels can be realized using currently available technologies or technological advances which are expected in the near future.
One objective of management of the disposal site is to collect and evaluate technical information to support decisions on permanent closure of the repository. In addition, monitoring the effects of repository construction and operation on the geological environment, as well as assessing the quality of emplacement of the engineered barriers, are primary elements of operational phase management.
