Abstract
U3Si2C2 is expected to be a new nuclear fuel as a ternary compound of uranium, silicon and carbon. However, the relevant research on U3Si2C2 under accident conditions is rarely reported. Hence it is necessary to explore the service behavior of the potential U-Si-C ternary nuclear fuel in extreme environments. In this work, the structural characteristics, electronic behaviors and mechanical properties of U3Si2C2, such as stable crystalline structures, density of states, charge distributions, electron localization function, electronic thermal conductivity and elastic modulus under extreme high pressure are calculated by density functional theory. The calculation results show that the lattice volume sharply increases when the external stress reached 9.8 GPa. Ionic and metallic nature coexist as to the bonding characteristics of U3Si2C2, and the ionic takes the dominant position in bonding. The toughness of U3Si2C2 is predicted to be better compared to U3Si2. Our theoretical investigation may help with the application of U3Si2C2-based fuel and the design of ternary uranium fuels.
Highlights
Since the Fukushima nuclear accident, the safety of fuel pellet in working and accident conditions has been paid increasing attention
Pressure is an important variable for nuclear fuel systems because of the local extreme pressure environment appearing in working conditions, and the pressure may cause the transformations of electronic and crystalline structures [24,25]
The density functional theory (DFT) theoretical calculations in this paper are carried out using Vienna ab initio simulations package (VASP) [37,38]
Summary
Since the Fukushima nuclear accident, the safety of fuel pellet in working and accident conditions has been paid increasing attention. The accident tolerant fuel systems (ATFs) have become a major concern of nuclear material research, attributing to its abilities of tolerance for the extreme working and accident conditions (high temperature, extreme pressure, irradiation, etc.). Pressure is an important variable for nuclear fuel systems because of the local extreme pressure (in the GPa range) environment appearing in working conditions (such as near the fission gas bubbles [23]), and the pressure may cause the transformations of electronic and crystalline structures [24,25]. Little is yet known on its evolution behavior under extreme pressure environment
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