Atomistic simulations of fission gas bubbles in nuclear fuels

This master thesis investigates the role of nano-bubbles porosity on some of the main thermo-physical properties of the (U,Pu)O2 nuclear fuel using atomistic simulations. In the last years the role of mixed oxides fuels became increasingly relevant for current and fourth generation reactors, and better understanding the properties of the compound is crucial, especially the consequences of its irradiation. The goal of this work is thus to calculate, using molecular dynamics simulations, the specific heat, the linear thermal expansion coefficient, the elastic coefficients and the thermal conductivity of porous (U,Pu)O2, covering a wide range of plutonium contents, temperatures and bubbles characteristics. The effect of the nano-bubbles is presented for every simulation and a general law is proposed for each property by fitting the results obtained. The newly proposed laws are suitable to be implemented in the fuel performance codes, which study the materials’ behaviour at a larger scale.