Flow laboratory investigation of ``F-type`` pitting of slugs and tubes

Technical Report · Mon Jun 01 04:00:00 EDT 1953

DOI:https://doi.org/10.2172/10186054· OSTI ID:10186054

Wilson, C D

Between June and August, 1952, a series of leaking process tubes were discovered in F and D Piles. All of the tubes, six from F and two from D, were removed and found to be leaking from a pitting attack that progressed from inside the tube walls. During this same period a serious slug pitting attack, not previously observed, was found on many slugs discharged at F Pile. Two hypotheses were presented that were considered that most likely explanations of the observed corrosion effects. The first mechanism-presented involved the process of cavitation. Briefly this hypothesis proposed that an obstruction to the water flow in the slug-tube annulus, such as a cocked slug or partially plugged annulus, caused the formation of a low pressure area capable of sustaining water vapor formation. The water vapor thus formed moved into the undisturbed, or higher pressure, regions of the annulus with the subsequent collapse of the vapor bubbles. This mechanism weakened or destroyed the protective oxide coat on the slugs and tubes, producing a localized corrosion phenomenon. The second hypothesis proposed to explain the observed effects was the erosion-corrosion hypothesis. This hypothesis presented the mechanism of protective aluminum oxide coat removal by the abrasive action of small particles in the water with succeeding corrosion of the unprotected aluminum metal. To obtain corrosion on the tubes and all over the slugs, as was the case with pitted slugs at F Pile, areas of extreme turbulence were considered necessary. Therefore cocked slugs, other restrictions in the annulus and extreme turbulence at slug junctions were prime requisites for this mechanism to be valid under normal operating conditions of flow rate and temperature. These two hypotheses were severely tested in flow laboratory equipment. This document is a report on the results of the laboratory experiments and the correlation of these data to in-pile corrosion data.

• Research Organization: General Electric Co., Richland, WA (United States). Hanford Atomic Products Operation
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 10186054
• Report Number(s): HW--28207; ON: DE95000696
• Country of Publication: United States
• Language: English

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