Phase Diagram of the Quasibinary System LiF–NaF–KF–CeF 3

eutectic mixture of lithium, sodium, and potassium fluorides is considered as a fuel salt for molten-salt reactors. For this reason, information about the solubility in it of fluorides of fissile materials and fission products is the most important when choosing a salt composition for a molten-salt reactor. In this work, the liquidus and solidus temperatures of the LiF–NaF–KF–CeF 3 quasi-binary system are determined by thermal analysis and differential scanning calorimetry. The system has one eutectic point at CeF 3 content 3 mol.% and temperature 445°C and three peritectic points – 7.5, 15, and 20.5 mol.% at 472, 512, and 600°C, respectively. The solubility of CeF 3 in LiF–NaF–KF is 10 mol.% at 500°C and reaches 25 mol.% at 665°С.