Oxide characterization for the mechanistic understanding of the initiation behaviors of Alloy 182 weld in various water chemistry conditions

A systematic program was initiated to mechanistically understand the crack initiation behaviors of Alloy 182 weld, which is known to be susceptible to PWSCC in PWR primary water environment. Both in-situ and ex-situ analysis techniques have been used to characterize the oxides on Alloy 182 welds formed in simulated PWR environments with varying DH (5 to 50 cc/kg) and Zn (0 to 30 ppb). For ex-situ analysis, SEM, TEM, EDS and XRD techniques were considered for surface and cross-sectional observation and characterization. For in-situ analysis, high-energy X-ray diffraction, Laser Raman Spectroscopy, EIS (Electrochemical Impedance Spectroscopy), and CER (Contact Electrode Resistance) techniques would be applied. The results of the oxide characterization by various methods would be correlated with the PWSCC initiation test results in simulated PWR environments. In this paper, the status and interim results of the program are described. (author)