LiCl-KCl eutectic is often used as the electrolyte in pyroprocessing of spent nuclear fuel. The corrosion of structural materials by LiCl-KCl eutectic is primarily affected by impurities. Purifying molten salt to reduce its corrosivity is one of the main ways to solve the material corrosion issue in pyroprocessing.

This study aims to investigate the effect of electrolytic purification on the corrosion of Inconel 600 by LiCl-KCl Eutectic molten salt.

The purification of LiCl-KCl salt was conducted by electrolysis method in this study and the cyclic voltammetry (CV) test was performed for monitoring the concentrations of impurities during the purification process. Inductively coupled plasma mass spectrometry (ICP-MS) measurement was performed for the salt to examine the impurity elements before and after purification. Inconel 600 alloy samples were subjected to a 500-h immersion corrosion test with purified and untreated LiCl-KCl salts under Ar atmosphere at 773 K. Scanning electron microscopy (SEM) and X-ray diffractometer (XRD) were employed to characterize the morphology and elemental distribution of the post-corrosion samples.

Experimental results show that the metal ion impurities are removed by electrolytic purification with the removal rates of Fe and Cr reach 46.1% and 51.4%. In argon protected environment, samples are corroded by untreated LiCl-KCl salts and LiCrO₂ generates on the surface of samples. Samples exposed to purified salts are less corroded than which exposed to untreated salts.

Electrolytic purification has a significant removal effect on metal ion impurities in LiCl-KCl salt, and effectively mitigates the corrosion of Inconel 600 by high-temperature molten salt.