Corrosion behavior of Alloy 690 after cessation of zinc addition in simulated PWR primary water at 330 °C

The purpose of this work is to quantify the effect of zinc cessation on corrosion and release rates from Alloy 690 steam generator tubes that were previously oxidized in zinc-containing water. The corrosion tests were performed in 2 ppm Li and 1000 ppm B water with and without 60 ppb zinc at 330 °C. The corrosion rates, release rates, and oxide thicknesses were determined based on descaling and gravimetric analysis methods and the results showed only a slight increase even after cessation of zinc addition. This is attributed to the zinc-containing chromium-rich inner oxide layer still remaining after the cessation of zinc addition.