Abstract. Since 2005, five national metrology institutes (NMIs) have submitted four new samples of known activity of ¹³¹I to the International Reference System (SIR) for activity comparison at the Bureau International des Poids et Mesures (BIPM). The latest activities ranged from about 2.8 MBq to 73 MBq. The submission of the CMI was to update an earlier submission. The key comparison reference value has been re-evaluated following the recommendations of the CCRI in May 2007. The degrees of equivalence between each equivalent activity measured in the SIR and the key comparison reference value (KCRV), and between each pair of participants have been calculated and the results are given in the form of a matrix for sixteen NMIs, including the previous participants. 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).