[en] We evaluated the accelerator beam power and the neutron-induced radioactivity of "9Be(p, n) boron neutron capture therapy (BNCT) neutron sources having a MgF_2, CaF_2, or AlF_3 moderator and driven by protons with energy from 8 MeV to 30 MeV. The optimal moderator materials were found to be MgF_2 for proton energies less than 10 MeV because of lower required accelerator beam power and CaF_2 for higher proton energies because of lower photon dose rate at the treatment position after neutron irradiation. - Highlights: • We examined moderators depending on proton energy about accelerator-based sources. • We evaluated γ-dose rate due to neutron-induced radioactivity about the sources. • MgF_2 was best for energy less than 10 MeV due to a lower accelerator beam power. • CaF_2 was best for energy more than 10 MeV due to a lower dose at a patient place.