Effects of Zinc Concentration on Oxide Films of Alloy 690 in PWR Primary Water

The effects of zinc concentration on the oxide films of alloy 690 were investigated in simulated pressurized water reactor(PWR) primary water. After exposed in 320 ℃ solutions with the zinc concentration of 10, 60, 120 μg/L, respectively, for 600 h , oxide films developed on the surface of specimens were analyzed by X-ray photoelectron spectroscopy (XPS). The results show that with the increase of zinc concentration, the weight gain rate decreased, and the oxide film became thinner. The range of effective zinc concentration to reduce corrosion rate was advised between 10 to 60 μg/L. The main compontents of the oxide film after exposure in zinc addition solutions were ZnCr2O4 and Cr2O3.