Equation of State of Uranium Dioxide

1 Introduction.- 1.1 Reactor Accident Analysis and Fuel Equation of State.- 1.2 The Role of Equation of State.- 1.3 Equation of State for Liquid UO2: Historical.- 1.4 Summary of the New Equation of State Features.- 1.5 General Notations.- 2 Governing Equations and Fundamental Formulae.- 2.1 Introduction.- 2.2 The Concept of Equation-of-State.- 2.3 Model Equations of State.- 2.4 Physical and Chemical Models in Thermodynamics of Reacting Fluids.- 2.5 Conclusions.- 3 Ionic Models for Liquid Urania.- 3.1 Restricted Primitive Ionic Model.- 3.2 Extended Ionic Model.- 3.3 Local Equations of State for the Liquid Phase: General Requirements.- 3.4 Improved Restricted Primitive Ionic Model.- 3.5 Compatibility Conditions.- 3.6 Determination of the Coulomb Contribution.- 3.7 Conclusions.- 4 Gas-Liquid Coexistence in Uranium Dioxide.- 4.1 General Conditions of the Phase Equilibrium.- 4.2 Calculation of the Equilibrium Composition and Thermodynamic Functions.- 4.3 General Structure of the Liquid-Vapour Phase Boundaries in UO2±x.- 4.4 Equilibrium Properties and Composition of UO2±x.- 5 Application of the Chemical Model within the van der Waals Approximation.- 5.1 Non-Congruent Evaporation over UO2±x.- 5.2 Oxygen Potential.- 5.3 Composition of the Liquid Phase.- 5.4 Discussion.- 5.5 Justification of the MIX Models.- 6 New Equation of State for Fluid Uranium Dioxide Based on Thermodynamic Perturbation Theory.- 6.1 Thermodynamic Perturbation Theory.- 6.2 Fluids Composed of Molecules with Anisotropic Interaction.- 6.3 Conclusions.- 7 Thermodynamic Properties of UO2, as Predicted by the New Equation of State.- 7.1 Summary of the Model Features.- 7.2 Calibration.- 7.3 Validation of the INTAS-99-EOS.- 7.4 Non-Congruent Equilibrium and Critical Point.- 7.5 Concluding Remarks.- A Appendix.-A.1.2 Volume Changes on Melting.- A.1.3 Thermal Expansion.- A.1.4 Elastic Properties and Adiabatic Compressibility.- A.1.6 Enthalpy and Entropy of Fusion.- A.1.8 The Congruently Vaporising Compositions of Urania.- A.2 Individual Components. Tables of Thermodynamic Functions.- A.3 Estimated Molecular and Ionic Interaction Constants.- A.3.1 Polarisability of Atomic O and U.- A.3.3 Dispersion Constants.- A.3.6 Conclusions.- A.4 Thermodynamic Tables.- References.