Radiation-induced nanostructure evolution models for Fe alloys

Neutron irradiation induces structural nano-scale changes in steels that in the long term cause degradation of the mechanical properties of the materials. These processes are important to understand to e.g ensure the integrity of the steel wall of the reactor pressure vessel during the operational life-time of a nuclear power plant. In this thesis, some of the irradiation defects have been studied by using as a model alloy the iron-carbon (Fe-C) system, as iron and carbon are the basic elements in any steel. Using the results from the MD studies of the characterisation of irradiation defects and the latest data collected from other MD, ab initio, Atomistic Kinetic Monte Carlo and rate theory studies in the literature, an OKMC model for the irradiation-induced nanostructure evolution in Fe-C has been constructed. The model was validated by reproducing experimental data in terms of vacancy and SIA cluster densities and mean sizes from irradiation experiments at low (340 K) and high operational temperature of light water reactors (560 K), as well as reproducing experimental data from an experiment of post-irradiation annealing up to 700 K.