Radioactive Contamination Under Applied Potentials in High Temperature Water

Experiments show that radioactive contamination of carbon steel and stainless steel by Co-60 in flowing, pressurized water at 573 K and pH 10.6 is affected by applied anodic or cathodic potentials. With no applied potential and under anodic potentials, Co-60 contaminates the surfaces mainly by incorporation in the growing oxide film. The rate of contamination of carbon steel is significantly decreased under anodic potentials because a more protective film is formed. A buildup of Co-60 activity is also observed under cathodic potentials where no film growth is expected; the major mechanism is postulated to be the reduction of dissolved Co ions to Co metal on the surface.