Athermal dislocation strengthening in UO2

Understanding the mechanical behavior of uranium dioxide (UO2) at high-temperature is of great interest to predict the behavior of the nuclear fuel under incidental operating conditions. Here, strengthening elementary processes and dislocation hardening coefficients are studied by the mean of Dislocation Dynamics (DD) simulations in UO2. The three slip modes of the fluorite structure i.e., ½<110>{100}, ½<110>{110} and ½<110>{111} are modelled and all the possible dislocation configurations are analyzed and discussed. Averaged hardening coefficients are derived and their sensitivity to the sample orientation is discussed in the light of the seminal experimental work of Sawbridge and Sykes. This DD study gives rise to new insights about UO2 mechanical behavior at high-temperature.