Atomistic simulations of the small xenon bubble behavior in U–Mo alloy

• An equation relating the bubble radii to the contained atoms is established.
• Critical temperature of coalescence increases with the distance between bubbles.
• Critical temperature of release increases with the distance from bubble to surface.
• Surface energy of U–Mo alloy is estimated between 0.45 and 0.5 J/m2.

The behavior of small xenon (Xe) bubble in U–Mo alloy fuel is investigated by the classical molecular dynamics (MD) simulations. The results indicate that the pressure in the Xe bubble is initially quite high and then rapidly decreases with the increasing Xe atoms until it reaches a minimum, and then slowly increases. The radius of Xe bubble increases rapidly with the increase of the number of Xe atoms at beginning and slows down at a high number of Xe atoms. The evolution processes of Xe bubbles coalescence in U–Mo alloy matrix and Xe gas atoms release near U–Mo alloy surface show that the critical temperature of the bubbles coalescence increases with increasing the initial distance between the centers of two bubbles and the critical temperature of the Xe atoms release increases with the initial distance from the center of bubble to the surface of the U–Mo alloy, respectively. The evolution processes of small Xe bubbles in the U–Mo alloy are similar although the Xe bubbles under the different initial conditions. The surface energy of U–Mo alloy is estimated between 0.45 and 0.50 J/m2, which is in accordance with the theoretical values of 0.43 and 0.5 J/m2 used in the literature.

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