Search

The electrolytic reduction of a spent oxide fuel involves the liberation of oxygen in a molten salt LiCl–Li2O electrolyte, which creates a corrosive environment for typical structural materials. In this study, the corrosion behaviors of Al–Y-coated specimens in a Li molten salt kept under an oxidizing atmosphere at 650 °C for 72 and 168 h were investigated. The weight loss fraction of the coated specimen to bare specimen was approximately 60% for 3% Li2O and 54% for 8% Li2O at 72 h, and approximately 38% for 3% Li2O and 30% for 8% Li2O at 168 h. Corrosion was induced in the LiCl–Li2O molten salt by the basic oxide ion O2− via the basic flux mechanism, and the corrosion product was found to be dependent on the activity of the O2− ion. The increase in weight loss may have been caused by the increase in the O2− concentration due to the increase in the Li2O concentration rather than being because of the increased reaction time. The Al–Y coating was found to be beneficial for hot corrosion resistance, which can be useful for handling high-temperature lithium molten salt under an oxidizing atmosphere. [ABSTRACT FROM AUTHOR]

Highlights • Corrosion mechanism of Ni-Co-based alloys in LiCl-Li 2 O molten salt is proposed. • Weight loss of alloys with low cobalt was less compared to those with high. • High content of Cr caused intergranular corrosion in the corrosion layer. • Excess Cr has a deleterious effect on kinetics during the hot corrosion process. Abstract In this study, hot corrosion behaviours of Haynes 282 (H282), Nimonic 90 (N90), and Haynes HR160 (HR160) in LiCl-Li 2 O molten salt were investigated at 650 °C under argon atmosphere. The corrosion rate was in the order of H282 < N90 < HR160, depending on the morphology and structure of the scale. H282 showed a localised corrosion behaviour, while N90 showed a uniform corrosion behaviour. For HR-160, intergranular corrosion was observed. The high Cr content caused intergranular corrosion in the corrosion layer. Thus, excess Cr has a deleterious effect on the corrosion kinetics during hot corrosion in LiCl-Li 2 O molten salt. [ABSTRACT FROM AUTHOR]

Spent nuclear fuel is electro-reduced in a chemically aggressive atmosphere wherein oxygen is generated at the anode in the presence of lithium molten salt containing a strong basic oxide, Li 2 O. Herein, the effect of the Li 2 O concentration on the hot corrosion behaviour of Haynes 263 and Inconel X-750 was investigated by immersion in molten LiCl–Li 2 O salt (1, 3, and 5 wt% Li 2 O) for 72–288 h at 650 ℃ under oxidizing atmosphere. For Li 2 O concentrations of approximately 3%, the weight loss and the products formed by the basic fluxing mechanism differed due to the dependence on the O2− concentration. • Effect of Li2O concentration on corrosion of Ni-based alloys was investigated. • Corrosion occurred by basic fluxing with O2 − ; products varied with ≥ 3 wt% Li2O. • Dense and continuous Cr-rich oxide layer prevented the inward diffusion of oxygen. • Ni-rich layer hindered outward diffusion of the alloying elements in the base metal. • Excess Fe appeared to be deleterious to the overall corrosion resistance. [ABSTRACT FROM AUTHOR]