Effects of different transition metal elements on the thermodynamic properties of thorium-based carbide nuclear fuels: A first-principles study

Multicomponent carbides, as a novel type of nuclear fuel, have attracted significant attention both domestically and internationally due to their excellent physical and chemical properties, such as high melting point, high hardness, and high-temperature stability. However, experimental measurements are expensive, complex, and subject to many uncertainties. In this work, high-throughput first-principles calculations were employed to systematically investigate the thermodynamic properties of (ThNb)C, (ThTa)C, and (ThZr)C. In addition, data from transition metal monocarbides of group IV and V were used for comparison. The impact rules of adding different elements to ThC on fundamental properties such as volume modulus, entropy, Gibbs free energy, and lattice thermal conductivity. With increasing temperature, the heat capacity value of (ThTa)C reached 35.06 J/(mol·K) and the entropy contribution of (ThTa)C was higher than that of (ThNb)C and (ThZr)C, indicating that (ThTa)C was more stable at high temperatures. Due to its larger volume modulus and lattice thermal conductivity, (ThZr)C has been found to have extensive application potential in the engineering field.