CORROSION POTENTIALS AND CORROSION BEHAVIOR OF AISI 304 STAINLESS-STEEL IN HIGH-TEMPERATURE WATER CONTAINING BOTH DISSOLVED HYDROGEN AND OXYGEN

The corrosion potential in high-temperature water is affected by the absolute and relative concentrations of dissolved hydrogen and oxygen as well as by mass transport of these species to the metal surface. The fact that the effects are more pronounced in water containing a stoichiometric excess of hydrogen suggests that the electrochemical oxidation of hydrogen on an oxide covered steel electrode is inhibited. The work also implies that when hydrogen injection is used to control the corrosion potentials, monitoring and maintaining low oxygen concentrations in the circulating cooling water is more important than maintaining a specific hydrogen level if the latter is in stoichiometric excess of the oxygen. These results have implications regarding corrosion potential control in boiling water reactors.