RD&D-Programme 2004 - SKB

A3.2 Facility design
A3.2.1 Encapsulation plant
As early as RD&D-Programme 92, SKB stipulated a siting adjacent to Clab as the main
alternative for siting of the encapsulation plant. During the period 1994–1996, planning and
preliminary design of the plant was carried out for this siting. To some extent, further planning
has awaited the results of the siting work for the deep repository. With the start of the site
investigations, however, the design of an encapsulation plant at Clab could be resumed as a
part of the work of compiling supporting material for a permit application, see Chapter 8.
There are several advantages of a location directly adjacent to Clab, for example that the
experience of fuel handling that exists at Clab can be taken advantage of, and that several of
the existing systems and plant components at Clab can be utilized. As an alternative, a siting
at a deep repository in Forsmark will be examined.
In view of the development situation and the plans for canister sealing technology, a decision
on a welding method will probably not be able to be made before early 2005. This choice affects
the design of the encapsulation plant. For the time being, the plant will therefore be designed
for both methods. Design of the encapsulation plant will continue after an application has been
submitted.
A3.2.2 Canister fabrication
Capacity for serial production of canisters should exist approximately one year before the
encapsulation plant is put into operation, i.e. about 2016. Most of the background material for
the crucial decisions as to where canister fabrication is to be located will become available in
5–6 years, according to the current timetable, i.e. after the application for the encapsulation
plant. Some background material on the planned canister factory will, however, be appended
to the permit application for the encapsulation plant, including a technical description. But the
siting work is not expected to have begun at the time of the application.
A3.3 Canister development
A3.3.1 Sealing
SKB is currently working on two alternative methods for sealing of the canister: EBW (electron
beam welding) and FSW (friction stir welding). A detailed description of the methods and the
development work is provided in Chapter 6. Full-scale equipment for both is on hand at the
Canister Laboratory. The intention is to decide in early 2005 which method is to comprise the
main alternative in the application. It is believed today that both methods can be used successfully.
Development of the welding methods is taking place at the Canister Laboratory with the support
of TWI (The Welding Institute) in the UK. The main stages in the work are:
• Process development.
• Process verification.
• Demonstration.
• Presentation/reporting of results.
• Compilation.
The most important steps in process development have already been taken for both welding
methods. The work has entailed building up an understanding of both welding processes, modifications
and improvements of equipment, and studies of how individual parameters control and
affect the welding results.
380 RD&D-Programme 2004