National comparison of activity measurements of ¹³¹I, ⁶⁰Co, and ¹³³Ba in Indonesia

National comparisons of radioactivity measurements of (131)I and (60)Co (in 2010) and of (133)Ba (in 2011) were carried out within the framework of the National Radiation Metrology Laboratory Program of Indonesia, coordinated by PTKMR-BATAN. Eleven laboratories took part in the comparison, and all measurements were made using gamma spectrometry, on point sources with an activity between 2000Bq and 6000Bq. Several laboratories reported values which were more than 10% different from the reference value for (131)I and (133)Ba. Possible reasons for these differences are discussed. This program will be continued with other radionuclides to maintain and control quality assurance for the local laboratories.