METHOD OF DOPING OR COATING METAL SURFACES WITH METALLIC ELEMENTS TO IMPROVE OXIDE FILM INSULATING CHARACTERISTICS

摘要

A method for mitigating general corrosion and crack initiation and growth on the surface of metal components in a water-cooled nuclear reactor. A compound containing a non-noble metal such as zirconium or titanium is injected into the water of the reactor in the form of a solution or suspension. This compound decomposes under reactor thermal conditions to release ions/atoms of the non-noble metal which incorporate in or deposit on the surfaces of the components, including the interior surfaces of any cracks formed therein. The compound may be organic, organometallic or inorganic in nature. Zirconium deposited inside a crack will reduce the electrochemical potential inside the crack even if the bulk surface zirconium is depleted under high fluid flow conditions. As a result, the electrochemical potential inside the crack is decreased to a level below the critical potential to protect against intergranular stress corrosion cracking.