A summary of k0-based R&D work on neutron activation analysis (NAA), internal mono standard NAA (IM-NAA) and prompt gamma-ray NAA (PGNAA)
is presented. The k0-based NAA was standardized by characterizing irradiation sites of research reactors, validated using reference materials
and applied to samples of different origin. Recently IM-NAA method was developed, validated for small and large size samples
and applied for the analysis of large size as well as non-standard geometry samples. Studies on PGNAA included characterization
of neutron beam, determinations of detection efficiency and prompt k0-factors, and analytical applications.