Experimental investigation on denting in PWR steam generators: causes and corrective actions
Denting studies have been undertaken in order to assess the influence of the most important parameters which could initiate corrosion of the carbon steel occurring in the tube-tube support plate crevices of some PWR steam generators. Tests have been carried out in model boilers where feedwater was polluted with sea or river water. Specific effects of chloride or sulfate and influence of oxygen content, magnetite addition and pH value were investigated. In magnetite prepacked crevices, denting is obtained within 1000 hrs for seawater pollution of 0.3 ppm chloride at the blowdown. In neutral chloride or in river water, denting is observed only with oxygen addition. Denting prevention is effective in the case of an on-line addition of phosphate, boric acid, or calcium hydroxide. For denting stopping, boric acid or calcium hydroxide is efficient even with a high seawater pollution. Soaks cannot stop denting if they are not followed by an on-line treatment (boric acid, calcium hydroxide). With quadrifoil holes, denting doesn't occur. In very severe test conditions, 13 percent Cr steel can be corroded, but the corrosion rate is low and oxide morphology is different from that growing on carbon steel.
- Research Organization:
- FRAMATOME, Groupe Chimie et Corrosion, Paris La Defense
- OSTI ID:
- 6697767
- Journal Information:
- J. Eng. Power; (United States), Journal Name: J. Eng. Power; (United States) Vol. 105:4; ISSN JEPOA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
210200* -- Power Reactors
Nonbreeding
Light-Water Moderated
Nonboiling Water Cooled
ALLOYS
BOILERS
CARBON STEELS
CORROSION DENTING
CORROSION PROTECTION
CORROSIVE EFFECTS
DEFORMATION
IRON ALLOYS
IRON BASE ALLOYS
MATERIALS TESTING
PWR TYPE REACTORS
REACTORS
STEAM GENERATION
STEAM GENERATORS
STEELS
TESTING
VAPOR GENERATORS
WATER COOLED REACTORS
WATER MODERATED REACTORS