Comments on a proposed mechanism of internal oxidation for alloy 600 as applied to low potential SCC

R. W. Staehle, Z. Fang

Research output: Chapter in Book/Report/Conference proceedingConference contribution

29 Scopus citations

Abstract

Internal oxidation (IO) has been proposed as a mechanism for the occurrence of low potential stress corrosion cracking (LPSCC) in Alloy 600. This proposal is analyzed here first by considering the possible diffusion of oxygen into metal as affected by potential. The results of this analysis show no correlation between the potential-dependent solubility of oxygen and the occurrence of LPSCC. A second analysis compares the occurrence of IO with direct measurements of oxygen diffusion in grain boundaries of nickel; here, the diffusion was determined to be negligible at steam generator operating temperatures. In a third analysis, the bulk diffusion of oxygen in nickel was analyzed to determine whether there could be any basis for a change in the diffusion kinetics of oxygen at lower temperatures. This analysis showed that there is no basis for deviating from the extrapolation of direct measurements of oxygen in grain boundaries measured at higher temperatures. A possible acceleration by a brittle film rupture model was analyzed, and it was found that such a mechanism associated with the IO mechanism is not reasonable. Various data suggested to support the IO model are considered briefly and found not to provide any unique support for the IO mechanism.

Original languageEnglish (US)
Title of host publicationProceedings of the Ninth International Symposium on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors -
EditorsS. Bruemmer, P. Ford, G. Was
PublisherMinerals, Metals and Materials Society
Pages69-78
Number of pages10
ISBN (Print)0873394755, 9780873394758
DOIs
StatePublished - Jan 1 1999
EventProceedings of the Ninth International Symposium on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors - - New Portbeach, CA, United States
Duration: Aug 1 1999Aug 5 1999

Publication series

NameProceedings of the Ninth International Symposium on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors -

Other

OtherProceedings of the Ninth International Symposium on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors -
CountryUnited States
CityNew Portbeach, CA
Period8/1/998/5/99

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