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- Smart, N.R., et al.
(författare)
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Further studies of in situ corrosion testing of miniature copper-cast iron nuclear waste canisters
- 2011
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Ingår i: Corrosion Engineering Science and Technology. - 1478-422X. ; 46:2, s. 142-147
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Tidskriftsartikel (refereegranskat)abstract
- To ensure the safe disposal of spent fuel in Sweden, SKB is planning to use the copper-iron canister in a granitic deep geological repository, surrounded by a compacted bentonite engineered barrier. In order to develop a deeper understanding of the internal corrosion behaviour of the design should a leak occur in the outer copper canister, a set of model canisters was set up in the Äspöunderground laboratory in contact with bentonite with a range of densities. The environmental conditions and electrochemical corrosion behaviour were monitored using a range of techniques. Water analysis and electrochemical measurements indicated an increase in the corrosion rate of both iron and copper in contact with low density bentonite, and of iron only in experiments with no bentonite present. This behaviour may be attributable to microbial activity. The measured corrosion rate depends on the technique used and it will be necessary to confirm the measurements by removal and examination of weight loss coupons. © 2011 Institute of Materials, Minerals and Mining.
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| 2. |
- Smart, N.R., et al.
(författare)
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In situ evaluation of model copper-cast iron canisters for spent nuclear fuel: A case of microbiologically influenced corrosion (MIC)
- 2014
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Ingår i: Corrosion Engineering Science and Technology. - 1478-422X. ; 49:6, s. 548-553
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Tidskriftsartikel (refereegranskat)abstract
- © 2014 AMEC Nuclear UK Limited. The Swedish method for disposal of spent nuclear fuel in a deep geological repository (KBS-3) relies on the stability of the granitic bed-rock and two engineered barriers: a copper-cast iron canister and highly compacted bentonite clay. In order to develop a better understanding of the internal corrosion processes that could take place if a leak were to occur in the outer copper canister, five miniaturised copper cast iron canisters were installed at a depth of 450 m at the ä spö Hard Rock Laboratory, in Sweden. The experiments differed in the density of the surrounding bentonite buffer, as well as in the number and position of leak points that were introduced in the copper shell. Several electrochemical techniques (e.g. AC impedance, linear polarisation resistance and electrochemical noise) were used to monitor the corrosion of different components of the experiment. Copper specimens were installed for post-test evaluation of the rate of general corrosion, localised corrosion and stress corrosion cracking (SCC). In addition, mechanical and environmental parameters, such as surface strain, hydrostatic pressure, redox potential, pH, water chemistry, dissolved gases, and microbial numbers, diversity, and activity were measured regularly. After five years of in situ exposure one of the canisters was retrieved and analysed to characterise and evaluate the corrosion processes that had occurred during the experiment. Extensive sulphide production by sulphate reducing bacteria led to rapid corrosion of iron, and the formation of iron sulphide deposits on the copper and iron electrodes disturbed the electrochemical measurements. This paper describes the various analyses that were carried out on the model canister and summarises the conclusions that can be drawn.
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