Abstract
Uranium silicides are envisaged as potential nuclear materials for the next generation. U3Si is featured by the high actinide density and the better thermal conductivity relative to UO2. To properly and safely utilize nuclear materials, it is crucial to understand their chemical and physical properties. First-principles in theory is mostly used to analyze the point defect structures for uranium silicides nuclear fuels. The lattice parameters of U3Si and USi2 are calculated and the stability of different types of point defects are predicted by their formation energies. The results show that silicon vacancies are more prone to be produced than uranium vacancies in β-USi2 matrix. The most favorable sites of fission products are determined in this work as well. According to the current data, rare earth elements cerium and neodymium are found to be more stable than alkaline earth metals strontium and barium in a given nuclear matrix. It is also determined that in USi2 crystal lattice fission products tend to be stabilized in uranium substitution sites, while they are likely to form precipitates from the U3Si matrix. It is expected that this work may provide new insight into the mechanism for structural evolutions of silicide nuclear materials in a reactor as well as to provide valuable clues for fuel designers.
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