Thermodynamic assessment of NaCl-MgCl2 eutectic composition

Abstract

Chloride salts have been proposed as promising candidates for both fuel and coolant salts in several small modular reactor (SMR) designs. The design and safety analysis of these reactor concepts relies on accurate data for molten salt thermophysical properties such as melting point. One salt mixture being considered is NaCl-MgCl₂ . There are limited experimental data available for this system and discrepancies have been identified in the reported melting points for the eutectic composition. To address this knowledge gap, a collaboration between University of New Brunswick’s Centre for Nuclear Energy Research (UNB-CNER) and the Canadian Nuclear Laboratories (CNL) was initiated. In this context, several compositions of NaCl-MgCl₂ were prepared and analyzed using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) to determine their melting points and thermal stability. This paper compares measurements of the melting point and thermal stability of NaCl-MgCl₂ near the eutectic composition to those reported in the literature. The DSC measurements performed at both CNL and UNB-CNER confirm that the melting point is lower than reported previously.