Recently it was found that wavelengths of some spectral lines well coincided with those of the radioactive elements with quite short lifetime. The origin of the appearance of short-lived isotopes in the Przybylski star atmosphere remains unclear. We consider the scenario explaining the appearance of heavy nuclei of some radioactive elements in the Przybylski star atmosphere as a result of its permanent irradiation by γ-quanta (photonuclear reactions) or by direct interaction between free neutrons formed there with seed nuclei of lighter elements (so-called r-process). In both cases the cause of the γ-quanta and free neutrons appearance can be a neutron star forming together with the Przybylski star the binary system. The neutron star is a source of fast electrons and positrons. The γ-quanta can appear due to the braking irradiation of the fast electrons and positrons in the stellar atmosphere after their interactions with the atomic nuclei that appear in the atmospheric plasma, while free neutrons can be formed during reactions of the direct capture of fast electrons by atmospheric protons (nuclei of hydrogen).