The standardization of standardless NAA

This review describes how the original 'standardless' (absolute and single-comparator) NAA-calibration methods, introduced in the mid-1960's were stepwise upgraded with respect to their accuracy and manageability, leading to the launching of the k0-method in the mid 1970s. Next, an account is given of the achievements in the continuous development of the k0-standardization of NAA up to the present. Topics highlighted are: the k0-data library, the development of dedicated calibration procedures, extensions and limitations, computerization and quality control/assurance. Finally, a short outline is given of the international dissemination of the k0-methodology. (author)