Abstract: A method for reducing the corrosion potential of steel vessels and piping used in nuclear reactors, in particular steel vessels and piping carrying high temperature water and/or steam which has a concentration of oxygen therein. A metal hydride is added to the water, the hydrogen of such metal hydride combining with oxidizing agents, typically oxygen, present in the water to reduce the concentration of such oxidizing agents. In the preferred embodiment the metal of the metal hydride is a metal that is capable of reacting with oxygen to form a substantially non-water soluble and substantially electrically insulating compound on the surface of the steel, and in particular is one that may react with and become deposited or incorporated into a pre-existing thin oxide film layer on the surface of the steel to thereby render such thin oxide layer substantially non-electrically conducting.

Abstract: An electrochemical corrosion potential sensor includes a sensor tip electrically joined to a conductor, and a ceramic insulator joined to the tip around the conductor. A sleeve is joined to the insulator around the conductor, and is electrically insulated from the tip by the ceramic insulator. The insulator has an exposed surface axially separating the tip and sleeve, and a ceramic coating is bonded thereto for preventing dissolution of the insulator by reactor water. In a preferred embodiment, the ceramic insulator is sapphire, and the ceramic coating is yttria-stabilized-zirconia or magnesia-stabilized-zirconia which may be plasma sprayed over the insulator.

Abstract: A method for mitigating crack initiation and propagation on the surface of metal components in a water-cooled nuclear reactor. A metal coating having an electrically insulating outer layer is applied on the surfaces of IGSCC-susceptible reactor components. The preferred metal coating is a zirconium alloy with a zirconia outer layer. The presence of an electrically insulating layer on the surface of the metal components shifts the corrosion potential in the negative direction without the addition of hydrogen and in the absence of a noble metal catalyst. Corrosion potentials.ltoreq.-0.5 V.sub.SHE can be achieved even at high oxidant concentrations and in the absence of hydrogen.

Abstract: A method for improving the performance and longevity of coatings of metal deposited from aqueous solutions of inorganic, organic or oraganometallic metal compounds. The method involves co-deposition of noble metal or corrosion-inhibiting non-noble metal during growth of oxide film on a component made of alloy, e.g., stainless steels and nickel-based alloys. The result is a metal-doped oxide film having a relatively longer life in the reactor operating environment. In particular, incorporation of palladium into the film provides greatly increased catalytic life as compared to palladium coatings which lie on the oxide surface.

Abstract: A method for mitigating initiation or propagation of a crack in a surface of a metal component in a boiling water reactor. The method includes the step of injecting a solution or suspension of a pH-adjusting compound into the bulk water of the reactor. The compound has the property of changing the pH of high-temperature water inside the crack from a value outside a predetermined pH range (namely, pH 6.0 to 8.0) to a value within the predetermined pH range without causing any significant change of the bulk water pH. The growth rate of the crack when the crack pH is outside the predetermined pH range is greater than the growth rate of the crack when the crack pH is within the predetermined pH range.