Impurity analysis in chloride salts using various analytical techniques

Mixtures of alkali and alkaline-earth fluoride and chloride melts are ideal candidates as heat-transfer and storage media in molten-salt reactors (MSRs) and in concentrated solar power (CSP) applications due to their low melting points and relatively high thermochemical stability. However, their utilization at elevated temperatures (500 – 800 °C) is currently limited due to impurity-driven corrosion of salt-facing structural alloys such as stainless steels. For this work, several analytical techniques were used to quantify trace impurities such as water, hydroxides, oxides and alloying elements in chloride salts, to better understand their chemistry and their effects on corrosion of salt-facing materials. Elemental analysis by ICP-OES and combustion were done to quantify alloying element, water and oxide impurities. Synchrotron X-ray diffraction was performed to quantify crystalline phases at varying purities of salts. This talk reports new insights into the chemistry of impurities in molten chloride salts and how they might affect the corrosion experiments.