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4. The passivity and corrosion resistance of carbon steel in simulated boom clay HLNW environments

Title: 4. The passivity and corrosion resistance of carbon steel in simulated boom clay HLNW environments
Author(s): D.D. Macdonald, O. Azizi, A. Saleh
Paper category : conference
Book title: NUCPERF 2009 - Long Term Performance of Cementitious Barriers and Reinforced Concrete in Nuclear Power Plants and Waste Management
Editor(s): V. L'Hostis, R. Gens, C. Gallé
Print-ISBN: 978-2-35158-072-1
e-ISBN: 978-2-35158-087-5
Publisher: RILEM Publications SARL
Publication year: 2009
Pages: 35 - 44
Total Pages: 10
Nb references: 9
Language: English

Abstract: In this paper, we report on a comprehensive study of the electrochemistry and corrosion behavior of carbon steel in contact with simulated concrete pore water and sulfur species-containing environments as are envisioned to exist within super containers for the disposal of High Level Nuclear Waste in Belgium’s proposed Boom Clay repository. The relevant environments are considered to be saturated Ca(OH)2 + Cl- with pH from 13 to 13.5 (adjusted with NaOH), with and without S2- and/or S2O3 2-. The experiments have been performed at temperatures from 23oC to 80oC. The steady-state current density of passive carbon steel increases with increasing thiosulfate and sulfide concentration, indicating that the degree of passivity decreases in the presence of these anions. In addition, the results show that the effect of 500 mg/l S2- on increasing the passive current density of carbon steel is more than 60 mg/l S2O3 2-. Mott-Schottky analysis reveals that the passive film formed on carbon steel in the presence of thiosulfate and sulfide, regardless of pH, is n-type in electronic character, and that the donor density in the film decrease with increasing the concentrations of these anions in the solution.
This result is contrary to the results obtained previously in the presence of chloride ion, where the donor density was found to increase with increasing chloride concentration.

Online publication: 2009-11-16
Publication type : full_text
Public price (Euros): 0.00

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