Effect of dissolved hydrogen on the electrochemical behaviour of Alloy 600 in simulated PWR primary water at 290°C

With an increase in dissolved hydrogen (DH) content from 0 to 5 cm(3) STP H(2)/kg H(2)O the electrochemical behaviour of Alloy 600 in deaerated PWR primary water at 290 degrees C was investigated, using corrosion potential (E(corr)) monitoring, potentiodynamic polarization, cyclic voltammetry and electrochemical impedance spectroscopy (EIS). DH content controls the E(corr), of Alloy 600. Raising DH content directly promotes the cathodic process and reduces the passivity of Alloy 600 significantly. EIS results show that increasing DH content results in a thinner inner-layer oxide film and ions diffusion becomes easier. The mechanism of these DH effects is discussed. (C) 2011 Elsevier Ltd. All rights reserved.