Quality control of indirect measure method for calibration of radioactive sources at a secondary standard dosimetry laboratory

In this work, a quality control program is illustrated with data obtained by a calibration system with an indirect method provided with an hyperpure germanium detector, normalized by the data obtained in a 4 π β-γ system as a direct method, consisting of proportional counter in coincidence with a NaI(T1) detector, or by activity values of the standard sources, certified and calibrated in a primary laboratory. The results obtained, for activities ranging from 10 sup(3) to 10 sup(6)Bq and many radionuclides, show that the accuracy of the measurements performed in a period of 4 years was better than 2%. When only one radionuclide is used, such as sup(137)Cs, the accuracy during a period of 3 years, was better than 0,5%. (author)