In 2004, the NMIJ, Japan and the NPL, UK submitted two new samples of known activity of ⁵¹Cr to the International Reference System (SIR) for activity comparison at the Bureau International des Poids et Mesures, with comparison identifier BIPM.RI(II)-K1.Cr-51. The activities were about 3.8 MBq and 7.9 MBq. The measurements update earlier submissions. The degrees of equivalence have been calculated between each of the equivalent activity results for the nine national metrology institutes measured in the SIR and the key comparison reference value (KCRV). At the same time as their submission to the SIR, the NMIJ sent an ampoule to the VNIIM to participate in the APMP.RI(II)-K2.Cr-51 comparison. The results of the VNIIM as described in this report are consequently linked to the BIPM comparison through the NMIJ. All the results are given in the form of a matrix with a graphical presentation.

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 Section II of the Consultative Committee for Ionizing Radiation (CCRI(II)), according to the provisions of the Mutual Recognition Arrangement (MRA).