RD&D-Programme 2004 - SKB

10 Deep repository – technology
Developing and demonstrating methods and technology for construction, operation and closure
of the deep repository is an important part of SKB’s work. This development work is aimed at
ensuring that methods and materials, as well as the technology needed to build the deep repository,
are available and that they meet stipulated requirements. It is also an important basis for
planning. The choice of materials, deposition technology etc is dependent on the requirements
that are made on the facility during different phases, for example with regard to reliability and
long-term safety. SKB is also investigating the possibilities of modifying the reference method
by depositing the canisters horizontally.
SKB conducts its own technology development, participates actively in various joint European
projects and follows others’ work in the field. Development, testing and demonstration in
preparation for the construction and operation of the deep repository are being conducted at the
Äspö HRL. Various technical solutions are being applied there on a full scale and in a realistic
environment.
10.1 Rock excavation technology
10.1.1 Requirements and premises
The choice of rock excavation technology will be made in the light of the following
requirements:
• Construction and operation shall have a limited impact on the safety functions of the rock
and the other barriers.
• Technical properties relating to loadbearing capacity and strength, fire protection, health and
environment, and accident prevention shall ensure safety for users and visitors.
• Rock investigations, rock works and deposition operation shall be possible simultaneously,
but in separate areas.
• Extention of the underground area shall be able to proceed at the desired pace and in a
cost-effective manner.
• Environmental impact shall be limited.
• Nearby residents shall be disturbed as little as possible.
The requirements influence both system and material choice and choice of methods for
execution. The choices can be influenced by information obtained from the site investigations.
10.1.2 Technology for rock extraction
As the deep repository is built out, large volumes of rock will be extracted during the excavation
of ramp, shaft, central area, main tunnels, deposition tunnels and deposition holes. Stress
redistributions and deformations will occur around the cavities that are created in the rock.
Conclusions in RD&D 2001 and its review
In RD&D 2001, SKB concluded that:
• Tunnelling can be done by conventional drill-and-blast or by mechanical excavation.
Both methods have been used with good results in tunnelling at the Äspö HRL.
• The damaged zone created during rock excavation by means of the two methods was
investigated, and the conclusion was that mechanical excavation created a smaller damaged
zone.
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