Molar heat capacity of uranium-rich U−Zr−Nb and U−Zr−Mo alloys

•Measurement of molar heat capacity of U−6(Zr+Nb) and U−6(Zr+Mo) alloys using DSC.•Molar heat capacity decreases with addition of 6wt% alloying element (Zr/Nb/Mo).•Replacement of Zr in U−Zr alloy with Nb/Mo reduces molar heat capacity.•Measured molar heat capacities are lower than that estimated by Neumann-Kopp rule.•Evaluation of molar enthalpy and entropy increments using molar heat capacity. Uranium-rich U−Zr−Nb and U−Zr−Mo alloys are considered to be good alternative fuel for fast reactors. From that prospective, number of selected uranium rich binary and ternary U−6X (X= Zr + Nb/Mo) alloy samples (i.e., U–6Zr, U−6Nb, U−2Zr−4Nb, U−4Zr−2Mo, U−2Zr−4Mo) with total alloying content of 6 wt% were prepared and characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) equipped with energy dispersive spectroscope (EDS) and differential thermal analyzer (DTA). Molar heat capacity is considered as one of the most important thermophysical properties of nuclear fuel. The molar heat capacity measurements of U–6Zr, U−2Zr−4Nb, U−6Nb, U−4Zr−2Mo and U−2Zr−4Mo alloys were carried out using differential scanning calorimeter (DSC) in the temperature range of 323−823 K. The U−6Zr alloy is considered here as the reference composition and the effect of Nb or Mo addition on the molar heat capacity data of U−6X alloys has been highlighted. The thermodynamic functions such as molar enthalpy increment Hm0(T)−Hm0(298.15K) and molar entropy increment Sm0(T)−Sm0(298.15K) of the alloy samples have been evaluated using measured molar heat capacity Cp,m0(T) data.