Abstract. Since 2005, the Institutul de Fizica si Inginerie Nucleara–"Horia Hulubei" (IFIN-HH) of Romania and the National Metrology Institute of Japan (NMIJ) have each submitted samples of known activity of ¹³³Ba to the International Reference System (SIR). The values of the activity submitted were about 1.4 MBq and 6.6 MBq. The IFIN result is their first contribution to the SIR for this radionuclide and for the NMIJ this key comparison result has replaced their earlier result dating from 1986. Each of these two new results has contributed to the updating of the KCRV for this radionuclide and is included in the matrix of degrees of equivalence in the key comparison database that now contains nine results for the comparison identified as BIPM.RI(II)-K1.Ba-133.

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).