Weld region corrosion during chemical cleaning of PWR (pressurized-water reactor) steam generators: Volume 2, Tests and analyses: Final report

Technical Report · Wed Jul 01 00:00:00 EDT 1987

OSTI ID:6175582

Barna, J L; Bozeka, S A; Jevec, J M; Miglin, B P; Scott, M E; Turner, C R; Beineke, T A; Fortier, M L; Machnicki, J P; Strohm, E O

The potential for preferential corrosion of steam generator weld regions during chemical cleaning using the generic SGOG solvents was investigated. The investigations included development and use of a corrosion assessment test facility which measured corrosion currents in a realistic model of the steam generator geometry in the vicinity of a specific weld during a simulated chemical dissolution of sludge consisting of essentially pure magnetite. A corrosion monitoring technique was developed and qualified. In this technique free corrosion rates measured by linear polarization techniques are added to corrosion rates calculated from galvanic current measured using a zero resistance ammeter to give an estimate of total corrosion rate for a galvanically corroding material. An analytic modeling technique was developed and proved useful in determining the size requirements for the weld region mockup used in the corrosion assessment test facility. The technique predicted galvanic corrosion rates consistent with that observed in a corrosion assessement test when polarization data used as model input were obtained on-line during the test. The test results obtained during this investigation indicated that chemical cleaning using the SGOG magnetite dissolution solvent can be performed with a small amount of corrosion of secondary side internals and pressure boundary welds. The maximum weld region corrosion measured during a typical chemical cleaning cycle to remove essentially pure magnetite sludge was about 8 mils. However, additional site specific weld region corrosion assessment testing and qualification will be required prior to chemical cleaning steam generators at a specific plant. Recommendations for site specific qualification of chemical cleaning processes and for use of process monitors and on-line corrosion instrumentation are included in this report.

• Research Organization: Babcock and Wilcox Co., Alliance, OH (USA). Research and Development Div.; Combustion Engineering, Inc., Windsor, CT (USA); Westinghouse Research and Development Center, Pittsburgh, PA (USA); Electric Power Research Inst., Palo Alto, CA (USA)
• OSTI ID: 6175582
• Report Number(s): EPRI-NP-5267-Vol.2; ON: TI87920520; TRN: 87-028096
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
36 MATERIALS SCIENCE
42 ENGINEERING
PWR TYPE REACTORS
STEAM GENERATORS
TUBES
CLEANING
WELDED JOINTS
CORROSION
MATERIALS TESTING
MICROSTRUCTURE
BOILERS
CHEMICAL REACTIONS
CRYSTAL STRUCTURE
JOINTS
REACTORS
TESTING
VAPOR GENERATORS
WATER COOLED REACTORS
WATER MODERATED REACTORS
210200* - Power Reactors
Nonbreeding
Light-Water Moderated
Nonboiling Water Cooled
360105 - Metals & Alloys- Corrosion & Erosion
420500 - Engineering- Materials Testing