Abstract. In 2006, two national metrology institutes (NMI) submitted samples of known activity of ⁵¹Cr solution to the International Reference System (SIR) for activity comparison at the Bureau International des Poids et Mesures (BIPM). Consequently, 28 samples have been submitted since 1977, from nine NMI and three other laboratories. The activities ranged from about 3 MBq to 90 MBq. The key comparison reference value (KCRV) has been updated and the degrees of equivalence between each equivalent activity measured in the SIR and the KCRV have been calculated. The results are given in the form of a matrix for eight laboratories to which the APMP.RI(II)-K2.Cr-51 results have been added. A graphical presentation is also given.

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 kcdb.bipm.org/.

The final report has been peer-reviewed and approved for publication by the CCRI Section II, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).