Examination of pits in Trojan nuclear power plant steam generator tubes: Final report
This report presents the results from examination of defects, oxides, and corrosion products on three steam generator tubes removed from the Trojan Nuclear Plant of Portland General Electric. In-generator eddy current inspection of the steam generator tubes suggested the probability of pits in one tube, located several inches above the tubesheet, within the height of the sludge pile. A weak indication was reported in the second tube, also within the height of the sludge pile. Copper signals were reported above the tubesheet and first support plate for the third tube which was removed. Destructive examination revealed numerous pits in a band several inches above the tubesheet. The depth of the pits corresponded to those anticipated by field eddy current testing. The pits contained a chromium rich iron and nickel depleted corrosion product with traces of copper and zinc. Intergranular penetrations were present at the base of the pits. Traces of sulfur and chlorine were found within the penetrations. Additionally, nickel sulfide and copper sulfide ribbons were present within the corrosion products of the pits. Sulfate and chloride anions were also observed in concentrations of hundreds of parts per million (each) within the exterior surface oxides. Hence, the pitting corrosion was attributed to acid forms of sulfur, acting synergistically with chlorides. The oxides on the external surfaces of the steam generator tubes were found to consist of magnetite (Fe/sub 3/O/sub 4/) with minor components of franklinite (ZnFe/sub 2/O/sub 4/). Embedded within this composite were numerous particles of copper in the elemental form. 8 refs.
- Research Organization:
- Electric Power Research Inst., Palo Alto, CA (USA); Combustion Engineering, Inc., Windsor, CT (USA). Nuclear Power Businesses
- OSTI ID:
- 6012139
- Report Number(s):
- EPRI-NP-6362-M
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
TROJAN REACTOR
CORROSION
DESTRUCTIVE TESTING
NONDESTRUCTIVE TESTING
PIPES
PROGRESS REPORT
STEAM GENERATORS
WATER CHEMISTRY
BOILERS
CHEMICAL REACTIONS
CHEMISTRY
DOCUMENT TYPES
ENRICHED URANIUM REACTORS
MATERIALS TESTING
POWER REACTORS
PWR TYPE REACTORS
REACTORS
TESTING
THERMAL REACTORS
VAPOR GENERATORS
WATER COOLED REACTORS
WATER MODERATED REACTORS
210200* - Power Reactors
Nonbreeding
Light-Water Moderated
Nonboiling Water Cooled