Damage characterization of displacement cascades in (U,PU)O$_2$ fuels by MD

Abstract

International audiencePlutonium based MOX fuels (U,Pu)O$_2$ are one of the most commonly used fuel in actual nuclear plants in France. However, little is known on its microscopic behaviour during irradiation. This is mainly resulting from the fact that experiments are difficult and expensive to set up with such compounds at such scales and conditions. Hence, atomistic simulations can bring valuable information and increase the scope of knowledge in this field. Molecular dynamics simulations have proved to be an excellent tool to study point defects creation, because of its intrinsic length and time scales. Therefore, we will present in this paper the first, to our knowledge, molecular dynamics simulations of displacement cascades in (U,Pu)O$_2$ solid solution. We will first present the assessment of four of the most recent rigid ions pair interactions for (U,Pu)O$_2$ solid solution by comparing their thermo-mechanical and thermophysical properties at different temperatures and plutonium contents. Then, the primary damage state under irradiation will be discussed by analysing the results of displacement cascades initiated with energies up to 500 keV and for different plutonium contents