A selected composition of the initial fuel of the Molten Salt Fast Reactor (MSFR) is assessed by differential scanning calorimetry (DSC) for melting point determination and by Knudsen effusion mass spectrometry (KEMS) for vaporization behaviour. Partial vapour pressures and thermodynamic activities of the MSFR fuel mixture are discussed indicating departures from ideal behaviour, and further interpreted by phase equilibria calculations. The boiling point of the mixture is obtained extrapolating vapour pressure experimental results. New results on the vaporization behaviour of pure uranium tetrafluoride are presented, together with the ionization potentials of UF₄ by electron impact.

通过差示扫描量热法（DSC）评估熔点，并通过克努森渗流质谱（KEMS）评估汽化行为，来评估熔融盐快堆（MSFR）初始燃料的选定成分。讨论了MSFR燃料混合物的部分蒸气压和热力学活性，表明其偏离了理想行为，并通过相平衡计算进一步解释。混合物的沸点是通过外推蒸气压得到的实验结果。提出了关于纯四氟化铀的汽化行为的新结果，以及通过电子撞击产生的UF ₄的电离势。