Abstract
Sulphur species in oxidation states between S2− and S6+ are known to interfere with the protective oxide films that form on steam generator tubing materials. By assisting in the breakdown of passive films, intermediate oxidation state sulphur species can cause intergranular attack and pitting of steam generator tubing over a wide pH range. Intermediate oxidation state sulphur species have also been observed to induce stress corrosion cracking of sensitized Alloy 600 at low temperatures.
This work employed electrochemical methods to investigate the effect of thiosulphate on the degradation of steam generator alloys (Alloy 600, Alloy 690, and Alloy 800). The effect of thiosulphate on steam generator tubing degradation was investigated at 150°C in crevice chemistries containing 0.0015 M sodium thiosulphate simulating the local chemistry environments developed in steam generator crevices or under sludge. The detrimental effect of thiosulphate on the boundary conditions of the recommended ECP/pH zone of Alloy 800 was discussed. Accelerated corrosion tests were also performed at selected potentials to confirm the detrimental effects of thiosulphate on the ECP/pH domain.
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References
Proceedings: Workshop on the Role of Sulphur Species on the Secondary-Side Degradation of Alloy 600 and Related Alloys”, Edited by U.E. Gustafsson and C.E. Shoemaker, NP-6710-SD, 1985 October.
W. Zhang, C. Lasowy and R. Newman, “Low Temperature SG Tubing Corrosion by Sulfur Species” (Proceedings of International Association for the Properties of Water Steam (IAPWS) Symposium, Niagara Falls, Ontario, Canada, July 21, 2010).
D. Durance, K. Sedman, J. Roberts, and J. Gorman, “FFS Issues for Steam Generator Tube (Top of Tubesheet) Intergranular Attack/Stress Corrosion Cracking” (Proceedings of the 17th International Conference on Nuclear Engineering (ICONE 17–75599), Brussels, Belgium, July 12–16, 2009).
C.M. Chen, K. Aral, and G.J. Theus, “Computer-Calculated Potential pH Diagrams to 300°C”, EPRI NP-3137, Volume 2 (1983).
A. Garner, “Thiosulphate Corrosion in Paper-Machine White Water”, Corrosion, 41(10), 587 (1985).
R.C. Newman, W.P. Wong, H. Ezuber, and A. Garner, “Pitting of Stainless Steels by Thiosulphate Ions”, Corrosion, 45(4), 282 (1989).
W. Zhang and R. Newman, “Localized Corrosion of Steam Generator Alloys at Low temperature in Mixed Solutions of Sulfate and Thiosulfate” (14th International Conference on Environmental Degradation of Materials in Nuclear Power Systems, Virginia Beach, VA, August 23–27, 2009).
M. Mirzai, C. Maruska, S. Pagan, O. Lepik, G. Ogundele, M. Wright and G. Kharshafdjian, “Stress Corrosion Cracking/Corrosion Fatigue/Fatigue in Alloy 600”, (Proceeding of 8th International Symposium on Environmental Degradation of Metals in Nuclear Power Systems-Water Reactors, Vol. 1, P. 11, American Nuclear Soc, Inc., La Grange Park, Illinois 1997).
A. Anderko, P. Wang, and M. Rafal, “Electrolyte Solutions: From Thermodynamic and Transport Property Models to the Simulation of Industrial Processes”, Fluid Phase Equilibria, 194–197, 1–20 (2002).
R.S. Greeley, W.T. Smith, Jr., R.W. Stoughton, and M.H. Lietzke, “Electromotive Force Studies in Aqueous Solutions at Elevated Temperatures, I: The Standard Potential of the Silver-Silver Chloride Electrode”, Journal of Physical Chemistry, 64, 652 (1960).
Z. Fang and R.W. Staehle, “Effects of the Valence of Sulfur on Passivation of Alloys 600, 690, and 800 at 25°C and 95°C”, Corrosion, Volume 55(4), 355–379 (1999).
Yucheng Lu, “Minimize Corrosion Degradation of Steam Generator Tube Materials”, (5th CNS International Steam Generator Conference, Toronto, Ontario, Canada, November 16–19, 2006).
Y.C. Lu, “Define Optimum Conditions for Steam Generator Tube Integrity And An Extended Steam Generator Service life”, (15th International Conference on Nuclear Engineering, Nagoya, Japan, April 22–26, 2007).
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© 2011 TMS (The Minerals, Metals & Materials Society)
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Chi, L., Lu, Y. (2011). Electrochemical Studies of Steam Generator Tube Degradation in the Presence of Thiosulphate. In: Busby, J.T., Ilevbare, G., Andresen, P.L. (eds) Proceedings of the 15th International Conference on Environmental Degradation of Materials in Nuclear Power Systems — Water Reactors. Springer, Cham. https://doi.org/10.1007/978-3-319-48760-1_64
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DOI: https://doi.org/10.1007/978-3-319-48760-1_64
Publisher Name: Springer, Cham
Online ISBN: 978-3-319-48760-1
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