RD&D-Programme 2004 - SKB

Newfound knowledge since RD&D 2001
No new knowledge has been forthcoming. The pilot tests that were conducted of the possibility
of studying SCC by measuring electrochemical noise gave negative results. The technique
turned out not to be applicable to measurements of stress corrosion cracking.
Programme
A study of SCC in acetate-containing water will be conducted during the coming three-year
period in cooperation with Posiva. In addition to this, a new pilot study is under way, this time
of the possibility of studying SCC by measuring acoustic emission from crack growth.
16.2.14 Grain growth in copper
Conclusions in RD&D 2001 and its review
The field was not judged to require any further research, development or demonstration; it
would be enough to monitor the field and take action when appropriate.
Newfound knowledge since RD&D 2001
No new knowledge has been forthcoming.
Programme
SKB makes the same judgement as in RD&D 2001, that it is enough to monitor developments
in the field.
16.2.15 Radionuclide transport
Radionuclide transport in the near-field is dealt with in section 18.3.
16.2.16 Integrated studies – evolution of damaged canister
If water enters a damaged canister, this leads to hydrogen gas generation, which increases the
pressure inside the canister, which in turn reduces the rate at which the water enters. At some
point when the pressure difference is small, inward diffusion of water vapour will be greater
than the inflow of water. The time until this occurs varies with assumptions concerning the size
of the hole and the corrosion rate, but is in most cases thousands of years. The inward diffusion
of water vapour means that corrosion will not cease completely. This will lead to a slow accumulation
of corrosion products and a pressure build-up inside the copper canister, which could
eventually damage the copper shell. To get a picture of the evolution of a damaged canister,
different processes must be modelled in an integrated fashion.
Conclusions in RD&D 2001 and its review
In SKI’s opinion, SKB’s previously reported model for a damaged canister shows that even
a defective canister has a significant barrier function. However, the authority is sceptical to
too literal an interpretation of the quantitative data obtained from the modelling of a damaged
canister and to the direct integration of the data into a consequence analysis.
Newfound knowledge since RD&D 2001
See section 16.2.7.
RD&D-Programme 2004 191