The continuously testing of stability of some dosimeter standards which used as reference dosimeter for calibrating survey meters have been carried out in Radiation Metrology Laboratory, P3KRBiN – BATAN. The testing is needed to know the accuracy and precision of dosimeter standard which fit the criteria as a SSDL (Secondary Standard Dosimetry Laboratory). Beside that this testing is a form of quality assurance of Radiation Metrology Laboratory as National Reference Laboratory or as a SSDL. Standard sources that used for the testing are Sr-90 with 6427 BA and 0941 BA serial numbers, from Buchler, Germany. The dosimeter standards, which tested, are Ion Chamber 2571/3154, 2581/327 and 2575/135 types with couple Farmer Dosimeters of 2570A/531 and 2570B/1319 types. The testing has been carried out routinely every month to make the standard apparatus is always ready for use. The result of the testing is fairly well and the standard apparatus is very stable.
