Corrosion evaluation of thermally treated Alloy 600 tubing in primary and faulted secondary water environments. [Alloy 600]

Technical Report · Fri Jun 01 00:00:00 EDT 1990

OSTI ID:6852487

Jacko, R J ^[1]

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1. Westinghouse Electric Corp., Pittsburgh, PA (USA)

The project compared the corrosion resistance of thermally treated (TT) Alloy 600 tubing with mill annealed (MA) tubing. In primary water, the TT extended the stress corrosion cracking (SCC) initiation time by at least 4 fold at 360{degree} (680{degree}F) and by greater than 10 fold in an accelerated 400{degree}C (752{degree}F) steam test. SCC initiation times in highly strained laboratory specimens indicated that SCC initiation followed a log-normal probability distribution with time. The variable SCC initiation time for MA tubing decreased with decreasing grain size,with decreasing intergranular carbide precipitation, increasing intragranular carbides and increasing cold work. SCC test were performed on C-ring specimens of Alloy 600 tubing in 1, 10 and 50 wt% NaOH solutions over the temperature range from 288 to 343{degree}C (550 to 650{degree}F). Both SCC initiation and growth were evaluated. For NaOH concentrations of 10% and less, and temperatures at or below 316{degree}C, the TT both increased the initiation time and decreased the observed depth of SCC. The improvement associated with thermal treatment was approximately an order of magnitude. With increasing temperature and caustic concentration, the advantage of TT gradually diminished. The influence of several sludge constituents on the corrosion properties of Alloy 600 was examined in deaerated NaOH solutions.

• Research Organization: Electric Power Research Inst., Palo Alto, CA (USA); Westinghouse Electric Corp., Pittsburgh, PA (USA)
• Sponsoring Organization: EPRI
• OSTI ID: 6852487
• Report Number(s): EPRI-NP-6721-M
• Country of Publication: United States
• Language: English

Related Subjects

22 GENERAL STUDIES OF NUCLEAR REACTORS
36 MATERIALS SCIENCE
INCONEL ALLOYS
INTERGRANULAR CORROSION
STRESS CORROSION
PRIMARY COOLANT CIRCUITS
SECONDARY COOLANT CIRCUITS
ANNEALING
CRACKS
GRAIN BOUNDARIES
HEAT TREATMENTS
SLUDGES
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STEAM GENERATORS
TEMPERATURE EFFECTS
TUBES
WATER CHEMISTRY
ALKALI METAL COMPOUNDS
ALLOYS
BOILERS
CHEMICAL REACTIONS
CHEMISTRY
COOLING SYSTEMS
CORROSION
CRYSTAL STRUCTURE
ENERGY SYSTEMS
HYDROGEN COMPOUNDS
HYDROXIDES
MICROSTRUCTURE
NICKEL ALLOYS
NICKEL BASE ALLOYS
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REACTOR COMPONENTS
REACTOR COOLING SYSTEMS
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220200* - Nuclear Reactor Technology- Components & Accessories
360103 - Metals & Alloys- Mechanical Properties
360105 - Metals & Alloys- Corrosion & Erosion