RD&D-Programme 2004 - SKB

welding and nondestructive testing is an important step that must be taken before production can
begin at the encapsulation plant, see Chapter 7.
SKB has started a project to design and plan for the construction of the encapsulation plant. It
can be sited adjacent to either Clab or the deep repository. It is an advantage if the plant can be
coordinated with existing activities, and SKB’s main alternative is therefore to co-site the plant
with Clab. Design of the plant will be based on the results of technology development and will
be coordinated with environmental impact assessment (EIA) – which leads to an environmental
impact statement (EIS) – as well as safety assessment and system analysis, see Chapter 8.
Transportation of the finished canisters from the encapsulation plant to the deep repository
is dealt with in Chapter 9.
The deep repository will be designed and engineered prior to the permit application.
Technology will be developed for mining of tunnels and sealing the rock around them,
fabricating and emplacing the buffer, handling the canisters, and finally backfilling and
plugging the deposition tunnels. Other areas being studied are sealing of boreholes and
technology for retrieving canisters after initial operation, if this should prove necessary. The
programme is described in Chapter 10. Design of the deep repository will be based on the
results of technology development and the site investigations, and coordinated with the EIA
work as well as safety assessment and system analysis, see Chapter 11. The reference design,
KBS-3V, consists of vertical deposition holes in horizontal tunnels. An alternative design will
also be investigated during the coming years, namely horizontal deposition of copper canisters,
KBS-3H. This will be done in close cooperation with the Finnish organization Posiva.
The deep repository must be safe even without supervision and maintenance, but some kind of
surveillance or monitoring may nevertheless be justified, for example to gain a better scientific
understanding of the site and the repository. Another important task is to ensure that no fissile
material can leave the facility while it is in operation. What requirements may be made and how
this can be handled is discussed in Chapter 12.
Safety assessment and research. The long-term safety of the repository is examined and
evaluated by means of the safety assessment. The first step is to describe the initial state of the
repository, after which possible long-term changes are explored, and finally the consequences
for man and the environment are described. Knowledge regarding long-term changes is obtained
from the research, whose purpose is to support the safety assessment and furnish it with the
necessary models and data. Input data for the safety assessment are also obtained from the
investigations of possible repository sites and the details of the technical systems. Conversely,
the needs of the safety assessment drive the need for research in the field and are essential for
both design studies and site investigations.
The safety assessment utilizes models that are developed in the research work and devises
special modelling tools for integrated modelling, see Chapter 14. The repository’s evolution
is simulated by system models. Transport of released radionuclides is calculated using both
numerical and analytical models.
The immediate goal of the safety assessment is a safety report that deals with deep disposal of
spent fuel and will be included in the permit application for an encapsulation plant. The project
is called SR-Can and will later be followed by SR-Site, aimed at an application for a deep
repository.
SKB’s research is largely aimed at analyzing the long-term safety of a deep repository with
spent fuel. The research programmes for the fuel, the canister as a barrier, the buffer, the backfill
and the geosphere are described in Chapters 15 to 19. Each part deals first with the research
on the initial state and then all processes, subdivided into radiation-related, thermal, hydraulic,
mechanical and chemical (including microbial), as well as processes related to radionuclide
transport. Chapters 20 and 21 deal with research aimed at charting the changes to which the
evolution of the biosphere and the climate give rise.
6 RD&D-Programme 2004