Stress corrosion cracking (SCC) is a potential threat to the integrity of the double shell tanks at the Hanford site, which store legacy waste from the nuclear weapons program. The SCC behavior of carbon steels similar in composition to the tank steels was investigated in a series of environments designed to simulate the chemistry of these wastes. Both slow strain rate tests using tensile specimens and constant load tests using compact tension specimens were performed. Based on the tests conducted, nitrite was found to be a strong SCC inhibitor. The cracking behavior also was a strong function of potential, and, in the majority of simulants, anodic polarization was required to promote SCC. These findings have driven the development of a field program at Hanford to measure corrosion potentials of the waste tanks and compare the results with the results of the laboratory SCC testing. The information obtained to date has shown that the tanks being monitored are operating at potentials out of the cracking ranges.

Subject
Test methods, Crack growth, Intergranular stress corrosion cracking, Stress intensity, Nitrites, Free corrosion potential, Stress cracking, Constants, Nitrates, Steel, Wastes, Stress corrosion cracking, Electrode potential
Keywords:
stress corrosion cracking, carbon steel, nitrate, nitrite, pH, Hanford, nuclear waste
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2014
Association for Materials Protection and Performance (AMPP)
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