Update of the BIPM comparison BIPM.RI(II)-K1.Ra-223 of activity measurements of the radionuclide ²²³Ra to include the 2021 result of the POLATOM (Poland)

Since 2014, 4 laboratories have submitted 4 samples of ²²³Ra to the International Reference System (SIR) for activity comparison at the Bureau International des Poids et Mesures (BIPM), with comparison identifier BIPM.RI(II)- K1.Ra-223. Recently, the POLATOM (Poland) participated in the comparison and the key comparison reference value (KCRV) has been updated. The degrees of equivalence between each equivalent activity measured in the SIR and the updated KCRV have been calculated and the results are given in the form of a table. A graphical presentation is also given. (author)