On the calculation of phase equilibrium of Thorium using van der Waals model

Thorium is an actinide substance with an atomic number of 90. Natural thorium is radioactive and, although not fissile, it undergoes a nuclear reaction (n, γ) and then beta radiation into a fissile material of the uranium. In this paper, some thermodynamic properties of the thorium have been investigated. On the other hand, the Equation of State (EOS) is an essential and suitable tool for studying the thermo-physical behavior of the materials and predicting them in different conditions in terms of pressure, temperature and amount. At present, there are different equations of state that can be categorized as theoretically, empirically, and semi-empirical. The purpose of this paper is to study some thermodynamic functions of thorium in liquid-vapor equilibrium such as vapor pressure, saturated liquid and vapor density, enthalpy and internal energy of vaporization using equations of state in the van der Waals model. In this model, the thermodynamic behavior of the materials is due to the contribution of the attractive and repulsive forces, which itself  is represented as a sum of the aforementioned statements mentioned above in a compressibility factor. In this research, we use the van der Waals equation, Berthelot equation, and the Radilich- Kwang equation. Our studies show the data obtained from Berthelot equation is in better agreement with experimental data for the studied thermodynamic functions quantitatively and qualitatively.