Material Development and Corrosion Study in Electrolytic Reduction Process of Spent Oxide Fuel

In order to explore the corrosion resistance of different structural materials in the process of electrolytic reduction and the effect of low concentration of Li2O on the corrosion behavior of materials, the corrosion behavior of Haynes C276, Inconel 600, Incoloy 800 and SS 316 in LiCl-Li₂O molten salt under the condition of Ar atmosphere and 650 ℃ was studied. The corrosion product and morphology were characterized by X-ray diffraction, scanning electron microscope and energy dispersive spectrometer techniques. The results indicate that all tested alloys exhibit selective dissolution of active alloy elements and different degrees of grain boundary attacks. The resistance to oxidation ranks in the order of Haynes C276>Inconel 600>Incoloy 800>SS 316. In the concentration (mass fraction) range of 1%-3.5%Li₂O, the detrimental effect of Li₂O by forming lithium chromium or nickel oxides are more pronounced. With the increase of Li₂O concentration, the oxidation corrosion of Inconel 600 is significantly enhanced, resulting in the increase of oxidation layer thickness from 2.3 μm up to 150 μm.