CORROSION STUDIES IN SIMULATED N-REACTOR SECONDARY SYSTEM WATER ENVIRONMENT

Technical Report · Wed May 01 04:00:00 EDT 1963

OSTI ID:4659364

Larrick, A P

Uniform corrosion and stress-corrosion-cracking tests were made in an out-of-reactor carbon steel pressurized water loop (TF-8) using simulated N- Reactor secondary system water. Materials tested were A212 carbon steel, AISI 304 stainless steel, 70-30 Cupro-Nickel alloy, Admiralty metal, and silicon bronze. Uniform corrosion rates were 0.08, 0.015, 0.05, 0.11, and 0.15 mil/yr, respectively. Stress-corrosion cracking was not observed on any of the alloys. A high initial corrosion of the carbon steel resulted in large amounts of corrosion product crud during the first two weeks of testing; crud levels were sufficiently high to plug the loop filter several times. After a protective oxide formed on the carbon steel surfaces, the corrosion rate and crud release rate were reduced to low values. The much higher blowdown rates attainable in the N-Reactor secondary system are expected to be sufficiert to maintain a tolerable crud level during initial startup. The hydrazine levels in the loop varied from 10 to 70 ppb compared to 10 to 20 ppb specified for N-Reactor. The excess hydrazine did not affect the resultant corrosion rates or water quality as verified by a short run where the hydrazine was intentionally maintained at 120 to 250 ppb. Additional testing of stressed AISI 304 stainless steel alternately dried and wetted in an N-Reactor secondary system-type environment failed to produce stress corrosion cracking, even when the water was contaminated with 5% Columbia River water. (auth) Alkaline permanganate solutions cause dendritic pitting in some hard-facing alloys. The magnitude of the pitting observed varied from 2 to 5 mils after 6 two-hour exposure periods in the laboratory tests. Variations in the concentration of either the potassium permanganate or the sodium hydroxide did little to alleviate the pitting corrosion. The pitting attack was not apparent at the lower temperatures; pitting first appeared at 50 deg C and increased in magnitude as the temperature increased and approaches 105 deg C, the maximum temperature studied. Chromium and iron were determined as the elements in the selectively dissolved alloyed phase. It was concluded that, if a system is decontaminated repeatedly, the critical valve surfaces such as in drain valves and/or isolation valves must eventually be replaced if a lesk tight system is to be maintained. (auth)

• Research Organization: General Electric Co. Hanford Atomic Products Operation, Richland, Wash.
• DOE Contract Number: AT(45-1)-1350
• NSA Number: NSA-17-037480
• OSTI ID: 4659364
• Report Number(s): HW-76358
• Country of Publication: United States
• Language: English

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