Stress analysis of pressurized water reactor steam generator tube denting phenomena. Interim report

Technical Report · Sat Jul 01 04:00:00 EDT 1978

DOI:https://doi.org/10.2172/6803020· OSTI ID:6803020

Thomas, J. M.; Cipolla, R. C.; Ranjan, G. V.; Derbalian, G.

In some Pressurized Water Reactor (PWR) steam generators, a corrosion product has formed on the carbon steel support plate in the crevice between the tube and support plate. The corrosion product occupies more volume than the original metal; the tube-to-support plate crevice volume is thus consumed with corrosion product, and further corrosive action results in a radially inward force on the tube and a radially outward force on the corroding support plate. This has resulted in indentation (''denting'') of the tube, accompanied by occasional cracking. Large in-plane deformation and cracking of support plates has also been observed in the most severely affected plants along with some serious side effects, such as deformation and cracking of inner row tube U-bends caused by support plate movement. Mechanical aspects of the tube denting phenomena have been studied using analytical models. The models used ranged from closed form analytical solutions to state-of-the-art numerical elastic-plastic computer program for moderate strains. It was found that tube dents, such as those observed in operating steam generators, are associated with yielding of both the tubes and support plates. Also studied were the stresses in tube U-bends caused by support plate flow slot deformation.

• Research Organization: Failure Analysis Associates, Palo Alto, CA (USA)
• OSTI ID: 6803020
• Report Number(s): EPRI-NP-828
• Country of Publication: United States
• Language: English

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Light-Water Moderated
Nonboiling Water Cooled
BOILERS
CHEMICAL REACTIONS
CORROSION
CORROSION PRODUCTS
DEFORMATION
PWR TYPE REACTORS
REACTORS
STEAM GENERATORS
STRESS ANALYSIS
TUBES
VAPOR GENERATORS
WATER COOLED REACTORS
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