EFFECT OF DISSOLVED HYDROGEN, SURFACE CONDITIONS AND COMPOSITION ON THE ELECTRONIC PROPERTIES OF THE OXIDE FILMS FORMED ON NICKEL-BASE ALLOYS IN PWR PRIMARY WATER

摘要

Photoelectrochemical ex-situ technique has been used to investigate the effects of dissolved hydrogen, surface conditions and chromium content on the semiconducting properties of the oxide films formed on nickel-base alloys in Pressurized Water Reactors (PWR) primary water. For this purpose, two hydrogen contents were used, the first one a low content of < 1 cm~3.kg~(-1) and the second one a high content of 43 cm~3 .kg~(-1). Also two nickel-base alloys were chosen, alloy 600 and alloy 690, and three kinds of surface preparations were applied 1200 abrasive paper, 1 μm diamond paste and colloidal silica. The main result concerns the effects of dissolved hydrogen on the semiconducting type of the oxide phase at the higher energies. This oxide phase, associated to the protective internal subscale, shifts from n-type at lower content of hydrogen to insulating behaviour while the content of hydrogen increases. The two other parameters chromium content and surface preparations have no influence on the electronic properties of the oxide scale.