Quantitative Calculation of Bubble Pinning to Grain Boundaries in Uo2: A Phase-Field Study

Abstract

A phase-field model was established to simulate the pinning effect of fission bubbles on moving grain boundaries (GBs) in UO2 nuclear fuel. It was found that the average velocity of the GB at different positions was obviously different during the movement of the GB with the participation of bubbles. The simulation results also showed that the maximum pinning force of bubbles to the GBs is related to the GB energy and the ratio of bubble diameter to bubble spacing (2r/L). The maximum pinning force decreases with the reduction of the 2r/L, which is consistent with the theoretical analysis results. In addition, the logarithm of the average grain size R has a linear relationship with the logarithm of the bubble volume fraction fv.

Keywords: Phase-field model, Pinning effect, Radiation-induced bubble, Uranium dioxide