Calorimetric investigations of UPb3 compound

• First time reporting of enthalpy increment and heat capacity data of UPb3 compound.
• First time reporting of high temperature calorimetric determination of enthalpy of formation of UPb3 compound.
• Miedema model was used to calculate enthalpies of formation of UPb3 and UPb.
• Thermodynamic table of the compound UPb3 was generated.

Interaction of uranium based metallic fuels and lead coolant can lead to formation of intermetallic compounds of U-Pb system. To understand U-Pb interactions, it is important to know thermodynamic properties of intermetallic compounds present in this system, UPb3 and UPb. In the present work, enthalpy increment, heat capacity and enthalpy of formation of UPb3 intermetallic compound were determined. The enthalpy increment was determined by high temperature Calvet calorimeter and heat capacity was determined using DSC. The heat capacity data was used to calculate thermodynamic parameters of the compound as a function of temperature. The enthalpy of formation at 843 K was determined using successive precipitation method, by direct reaction calorimetry. The enthalpy of formation at 843 K, from Pb(l) and U(l), was −28.9 kJ at-mol−1 and after adjusting enthalpy increments of pure elements and compound, the enthalpy of formation of the compound at 298 K, from Pb(s) and U(α) was found to be −20.0 kJ at-mol−1.