Stress corrosion cracking (SCC) of Inconel 600 tubing1 is a concern in nuclear reactor steam generators. Examination of the effect of SCC on remaining tube integrity requires representative defected specimens. Out-of-service specimens are not generally available and require handling of radioactive material. A laboratory method has therefore been devised to place controlled stress corrosion cracking in nonsensitized Inconel tubing.
Schematic representation of the equipment setup is shown in Figure 1. All components subject to the heated stress corrosion cracking medium, the autoclave, and adjacent fittings are made of Ni-200 which is shown to be resistant to SCC in caustic media.2,3 Other system components are Inconel 600 or 316 stainless steel. The solution developed for stress corroding the nonsensitized Inconel consists of 600 g/L NaOH, 0.1 g/L Cu (electrolytic dust) and 6 g/L CuO (as powder). The presence of copper is necessary for the SCC process.
Control of...
