Formation energies and swelling of uranium dioxide by point defects

► Ab initio full potential quantum mechanical study of rare gases in uranium dioxide. ► Octahedral interstitial and oxygen and uranium substitution sites are considered. ► Anti-ferromagnetic UO2 phase with and without spin-orbit coupling are considered. ► Lattice constants and formation energies increase with the rare gasesʼ radii. ► The octahedral interstitial position is the most favorable occupation site.