Since 1978, seven national metrology institutes have submitted 15 samples of known activity of ⁵⁸Co to the International Reference System (SIR) for activity comparison at the Bureau International des Poids et Mesures. The activities ranged from about 0.3 MBq to 9 MBq. The degrees of equivalence between each equivalent activity measured in the SIR and the key comparison reference value (KCRV) have been calculated and the results are given in the form of a matrix for six NMIs. A graphical presentation is also given.

The results of an APMP regional comparison, comparison identifier APMP.RI(II)-K2.Co-58 held in 2000 for this radionuclide have been linked to the SIR results through that of the NMIJ. This has enabled six other NMIs to have degrees of equivalence in the KCBD.

Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database www.bipm.org/kcdb.

The final report has been peer-reviewed and approved for publication by Section II of the Consultative Committee for Ionizing Radiation (CCRI(II)), comparison identifier BIPM.RI(II)-K1.Co-58, according to the provisions of the Mutual Recognition Arrangement (MRA).