This paper reports the spectroscopic properties of praseodymium-doped phosphates, KLuP2O7, Sr9Sc(PO4)7, K3Lu(PO4)2 doped with Pr3+ ions. Spectra of photoluminescence (PL) upon selective UV photon excitation, PL excitation spectra as well as luminescence spectra and decay kinetics upon pulse synchrotron X-ray excitation were studied. Recordings of luminescence spectra were done with pure samples and after irradiating with fast electrons (E = 10 MeV) using linear electron accelerator. The absorbed dose varied in the range of 150–300 kGy. Pure samples demonstrated three typical channels of emission: interconfigurational d – f transitions, intraconfigurational f – f transitions and defect-related luminescence. After irradiating, two scenarios of changing optical properties were investigated: increasing of defect-related luminescence impact in total light output and “suppressing” of defect-located energy emission.