Nickel Alloy Stress Corrosion Cracking in Neutral and Lightly Alkaline Sulfate Environments

Bouvier, O. de; Prieux, B.; Vaillant, François Le; Bouchacourt, M.; Lemaire, P.

doi:10.1002/9781118787618.ch72

Cited by 9 publications

(2 citation statements)

References 2 publications

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“…The behavior of alloy 800 NG secondary water chemistry of PWR with sulfates in a neutral or slightly alkaline environment has been studied by Bouvier of EDF [13]. The dilution used was intended to be representative of existing environments in flow restricted areas and consisted of deionized water with additions of sulfuric acid and caustic soda to achieve pH between 5 and 9.5 at 320°C and sulfate concentrations of 100ppm, 5000ppm (0.05M), and 57000ppm (0.6M).…”

Section: Failure Analysis Discussionmentioning

confidence: 99%

Failure Analysis of Steam Generator Tubes

Diego¹,

Merino²

2023

Failure Analysis - Structural Health Monitoring of Structure and Infrastructure Components

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Steam generator fabricated of alloy 600 tubes has been replaced in the last decades by newer versions built with alloy 690 or alloy 800 tubes. At first, it was thought that both alloys were resistant to SCC mechanisms but after several years of operation, some NPPs developed denting processes and IGSCC, especially in alloy 800. Corrosion products accumulated in the crevice area between tube-sheet and secondary tube surface of SG increase the stresses and produce a chemical more aggressive to the environment. These two points are the main factor to occur “denting” and increase the possibility of ODSCC can be developed. This chapter describes the failure analysis of an alloy 800 SG tube with only nine years of operation. Microstructural characterization of sludge was carried out after the cleaning by mechanical tube sheet water lancing. SEM/EDX, surface analysis by Auger, and XPS spectroscopy were used to identify chemical species over the OD surface and the fracture surface of some open cracks. \"Denting\" mechanism is related to flow accelerated corrosion and oxidant particles introduced into secondary side of SG. Therefore, it is convenient to prevent the impurities intake into SG and perform a chemical cleaning process to avoid the hard sludge formation.

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Section: Failure Analysis Discussionmentioning

confidence: 99%

Failure Analysis of Steam Generator Tubes

Diego¹,

Merino²

2023

Failure Analysis - Structural Health Monitoring of Structure and Infrastructure Components

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“…Sulfate ions are involved in the deposition as the corrosion of loops generates colloidal particles, due to the solubility limits of corrosion products or detachment of small pieces of material [64][65][66]. Previous studies found that the deposition on the SG tubes was mainly composed of magnetite and sulfate ions, especially in flow restricted areas they were likely to promote corrosion [67,68].…”

Section:  Sulfate Ionsmentioning

confidence: 99%

Corrosion and deposition on the secondary circuit of steam generators

Xie

Zhang

2016

Journal of Nuclear Science and Technology

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This study conducts a critical review on the studies of material corrosion and deposition on the secondary circuit of a pressurized water reactor, especially on the steam generators (SGs). Available knowledge has shown that the structural materials in the environment of the secondary circuit are susceptible to flow-accelerated corrosion and deposition-induced degradation. The deposition of the non-volatile impurities, especially the corrosion products, on the SG surfaces can be a primary cause of material degradations, including stress corrosion cracking. The review will analyze the fouling mechanisms and behaviors, the source of impurities, corrosion mechanisms, and the factors that affect the deposition and corrosion behaviors.

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