High entropy alloys (HEAs), a new type of material system, have potential application as a structural material in advanced nuclear energy systems due to their impressive mechanical properties. The goal of my project is to evaluate and understand ion and neutron irradiation effects in a FeCrMnNi HEA through comprehensive experimental characterization (XRD, TEM, Tensile test, hardness, etc) and state-of-art modeling techniques (Ab initio methods, Molecular Dynamics, Monte Carlo, etc).