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Mechanical Properties of Oxides Formed by Anaerobic Corrosion of Steel

Published online by Cambridge University Press:  21 March 2011

N.R. Smart
Affiliation:
AEA Technology plc, Culham Science Centre, Abingdon, Oxfordshire, OX14 3ED, United Kingdom, Email: [email protected]
A.E. Bond
Affiliation:
AEA Technology plc, Culham Science Centre, Abingdon, Oxfordshire, OX14 3ED, United Kingdom, Email: [email protected]
J.A.A. Crossley
Affiliation:
AEA Technology plc, Culham Science Centre, Abingdon, Oxfordshire, OX14 3ED, United Kingdom, Email: [email protected]
P.C. Lovegrove
Affiliation:
British Gyroplanes Ltd, Wallingford, Oxfordshire, OX10 OJA, United Kingdom
L. Werme
Affiliation:
SKB, Box 5864, SE-10240, Stockholm, Sweden
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Abstract

In Sweden, it is proposed that spent nuclear fuel should be encapsulated in sealed cylindrical canisters for disposal in a geologic repository. The canisters would consist of a thick ferrous inner container and a copper overpack. If mechanical failure of the copper overpack occurred, allowing water to enter, there would be a build up of ferrous corrosion product, which could induce stresses in the outer copper canister. This paper describes an apparatus, the ‘stress cell’, which was designed to measure the expansion caused by the anaerobic corrosion of steel under compressive loads. The apparatus consisted of a stack of steel and copper discs, which were immersed in simulated anoxic groundwater. A system of levers amplified the change in height of the stack, and the displacement was measured using sensitive transducers. Three cells were set up; two contained alternate mild steel and copper discs, and the third, a control cell, consisted of alternate stainless steel and copper discs. A slight contraction of the control cell was observed but no expansion was measured in the mild steel - copper cells.

In parallel, coupons of mild steel and cast iron were corroded in anoxic, artificial groundwater at 50°C and 80°C for several months. The coupons were examined by atomic force microscopy (AFM) to determine the mechanical properties and the structure of the corrosion product films, and X-ray photoelectron spectroscopy (XPS) to identify the chemical composition of the film.

Type
Research Article
Copyright
Copyright © Materials Research Society 2001

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References

REFERENCES

1. Smart, N.R., Blackwood, D.J. and Werme, L., submitted to Corrosion (2000).Google Scholar
2. Bond, A.E., Hoch, A.R., Jones, G.D., Tomczyk, A.J., Wiggins, R.M., Worraker, W.J., Assessment of a Spent Fuel Disposal Canister. Assessment Studies for a Copper Canister with Cast Steel Insert, SKB Technical Report TR-97-19, (1997).Google Scholar
3.SKB Deep repository for Spent Fuel Nuclear Fuel, SR 97 - Post-closure safety, SKB Technical Report TR-99-06, (1999).Google Scholar