Effects of 10 MeV electron and fast reactor neutron irradiations on carrier removal rate and deep traps spectra were compared for undoped n-GaN samples. It is shown that for electron irradiation the carrier removal rate is well accounted for by the difference in introduction rates of nitrogen-vacancy-related donors with activation energy 0.2 eV and of nitrogen-interstitial-related acceptors at Ec-1.2 eV. In the case of neutron irradiation the introduction rate of all deep traps was much lower than the carrier removal rate indicating that the main contribution to electron removal was due to disordered regions. These regions give rise to a marked persistent photocapacitance signal and a hole-trap-like feature in deep traps spectra. The Fermi level position in the core of disordered regions is located near Ec-(0.85-1) eV.