Corrosion tests of various alloys in fluorides of lithium, sodium and potassium (FLiNaK) medium for molten salt reactors in the temperature range of 550-750ºC using electrochemical techniques

Abstract

Hydrogen (H₂) is an alternative to petroleum based environment polluting transport fuel. High temperature process heat in the range of 500-1000°C is needed for (H₂) production by water splitting. This heat can be generated in molten salt nuclear reactors. Compatibility of materials is a bottle neck problem in this process. Corrosion behaviours of different alloys have been evaluated in fluoride eutectic FLiNaK in the temperature range of 550-750°C under static and dynamic conditions. Electrochemical polarization and impedance techniques have been used to estimate corrosion rate. The results show that the corrosion process is controlled by activation and in some cases by formation of passive layer. In static mode, the corrosion rates followed the order: Inconel 625 > Inconel 617 > Inconel 600 > Incoloy 800 > Ni 220 > Hastelloy N > Incoloy 800 HT. In dynamic mode, Haselloy N and Incoloy 800 show better corrosion resistance in comparison to other alloys.