Effect of Water Chemistry on the Erosion-Corrosion of Aluminum in High Temperature High Velocity Water^⋆

Laboratory experiments were conducted to simulate the erosion-corrosion of aluminum fuel cladding in water-cooled, plutonium producing, nuclear reactors. Water quality was demonstrated to be critical in causing erosion-corrosion attack on aluminum in high temperature pressurized water. Very little attack occurred in distilled water, whereas attack was progressively worse in river water and well water. The extreme attack in well water was simulated by dissolving 50 ppm CaCO₃ and 10 ppm SiO₂ in distilled water. A distinct corrosion enhancing synergism was apparent between dissolved bicarbonate and silicate ions. In situ recordings of electrochemical potential vs time were characteristic of the extent of erosion-corrosion which was occurring on a particular specimen. Polarization resistance measurements did not have the expected sensitivity to erosion-corrosion, probably because of the complex cell geometry imposed by the erosion-corrosion testing apparatus.