Formation, Diffusion, and Growth of Gas Bubbles in γ-Uranium with the Excess of Interstitial Atoms: Relation between Molecular Dynamics and Kinetics

EA Lobashev and AS Antropov and VV Stegailov, JOURNAL OF EXPERIMENTAL AND THEORETICAL PHYSICS, 136, 174-184 (2023).

DOI: 10.1134/S1063776123020103

The formation of gas nanobubbles through the merging of individual fission products of uranium is an important process for the evolution of nuclear fuels. The theoretical description of this process is very difficult because both the dynamics of individual atoms in the lattice and the kinetics of evolution of an ensemble of bubbles should be taken into account within a unified model. Such a model is constructed in this work on the basis of molecular dynamics simulations for xenon bubbles in bcc uranium in the case of the excess of interstitial atoms in the crystal matrix. The analysis is based on the molecular dynamics simulation of the nonequilibrium process of formation of xenon nanobubbles from individual Xe atoms dissolved in the crystal matrix. A relation between the size of bubbles and the number of gas atoms in them, as well as the dependence of the diffusion coefficient of bubbles on their radius and the number of interstitial atoms in the gamma-U matrix, has been analyzed. A kinetic model of evolution of the ensemble of bubbles has been proposed to describe the molecular dynamics results and to extrapolate them to long times.

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