Thermodynamic optimization of the constitutive binaries of the LiCl/RbCl/CaCl2-NaCl-UCl3-PuCl3 systems

• Published in: Calphad 2022-06, Vol.77, p.102427, Article 102427
• Main Authors: Yin, Huiqin, Wu, Xiaomin, Ling, Changjian, Lai, Xing, Hu, Biao, Tang, Zhongfeng
• Format: Article
• Language: English
• Subjects: Calcium chloride; CALPHAD; LiCl/RbCl/CaCl2-NaCl-UCl3-PuCl3; Liquid phases; Liquidus; Lithium chloride; Mathematical models; Melt temperature; Molten salt; Molten salt nuclear reactors; Nuclear fuels; Optimization; Parameters; Phase diagrams; Solid solutions; Systems analysis; Thermodynamics
• ISSN: 0364-5916; 1873-2984
• DOI: 10.1016/j.calphad.2022.102427

This study is aiming at building a set of self-consistent thermodynamic database of the constitutive binaries of the LiCl/RbCl/CaCl2-NaCl-UCl3-PuCl3 systems, and evaluating whether LiCl, RbCl or CaCl2 is an appropriate additive of NaCl-UCl3-PuCl3 matrix fuel of Molten Salt Reactor in terms of CALculation of PHAse Diagrams (CALPHAD) method. Substitutional solution model was adopted to describe the liquid phase and solid solution phase, while compound energy formalism was used to depict the intermediate phases. The model parameters were optimized based on the experimental data and theoretical predicted values. The thermodynamic parameters for describing the constitutive binaries of LiCl/RbCl/CaCl2-NaCl-UCl3-PuCl3 were ultimately obtained. Phase diagram information such as liquidus surface projections, isothermal sections and vertical sections of the LiCl/RbCl/CaCl2-NaCl-UCl3-PuCl3 system were predicted from the models with the optimized parameters. The effect of LiCl, RbCl and CaCl2 on the isothermal sections and melting temperature of NaCl-UCl3-PuCl3 matrix fuel was also investigated. The results show that RbCl is suitable as the candidate additive component of NaCl-UCl3-PuCl3 matrix fuel from the thermodynamic viewpoint, while LiCl and CaCl2 not. This work not only enriches the thermodynamic databases of NaCl-UCl3-PuCl3 matrix fuel, but also provides a direct guidance for the design and preparation of nuclear fuel in the Molten Salt Reactor. •The thermodynamic databases of RbCl-AnCl3 (An = U and Pu) were firstly built.•Effect of LiCl, RbCl and CaCl2 on the thermodynamic behavior of NaCl–UCl3-PuCl3 was studied.•Liquid surface projection, isothermal section and vertical section were analyzed.•RbCl is an appropriate candidate additive of NaCl–UCl3-PuCl3 fuel, while LiCl and CaCl2 not.