In this paper we review the current status of our efforts to model the Fe–Cr system, which is a model alloy for high-Cr ferritic–martensitic steels, using large-scale atomistic methods. The core of such methods are semi-empirical interatomic potentials. Here we discuss their performance with respect to the features that are important for an accurate description of radiation effects in Fe–Cr alloys. We describe their most recent improvements regarding macroscopic thermodynamic properties as well as microscopic point-defect properties. Furthermore we describe a new type of large-scale atomistic kinetic Monte Carlo (AKMC) approach driven by an artificial neural network (ANN) regression method to generate the local migration barrier for a defect accounting for the local chemistry around it. The results of the thermal annealing of the Fe–20Cr alloy modelled using this AKMC approach, parameterized by our newly developed potential, were found to be in very good agreement with experimental data. Furthermore the interaction of a 1/2 〈1 1 1〉 screw dislocation with Cr precipitates as obtained from the AKMC simulations was studied using the same potential. In summary, we critically discuss our current achievements, findings and outline issues to be addressed in the near future development.