Determining the impact of sacrificial magnesium corrosion control for selected alloys in a Molten Salt Reactor

Abstract

Molten Salt Reactors (MSRs), a Generation IV nuclear reactor concept, provide low-pressure and high-temperature operation, while corrosion control and salt environment material compatibility remain challenging. This study continues static molten salt immersion experiments from previous research to evaluate long-term corrosion mechanism of molten chloride salt on 316 Stainless Steel and Nimonic® Alloy PE16, and to investigates using magnesium metal addition for corrosion control at 550℃. Significant apparatus design improvements and seal performance were accomplished. The experiments demonstrated Cr depletion and MgO formation on the alloy surface and theses are recognized as major corrosion mechanisms of Nimonic® Alloy PE16 in a molten eutectic NaCl and MgCl2 salt mixture. Mg-metal addition reduces molten salt impurities, but intermetallic compound formation between Mg and Ni causes dealloying. This research contributes to optimizing the experimental framework the molten chloride salt corrosion experiments and recommends selected alloys for compatibility in MSRs for research and development purposes.