Preparation of 137Cs and 60Co sealed sources based on inorganic sorbents for radiometric calibration purposes

Sealed sources of 183.15 ± 5% kBq (4.95 ± 5% μCi) 137Cs and 38.48 ± 5% kBq (1.04 ± 5% μCi) 60Co based on inorganic sorbents were easily prepared, standardized, and successfully passed quality control tests. 137Cs (t1/2 = 30.07 y) radionuclides were sorbed by equilibration of 137CsNO3 solution with 6-tungstocerate(IV) inorganic ion-exchanger at pH 3 for 48 h at 25 ± 1 °C, whereas 60Co (t1/2 = 5.27 y) radionuclides were retained by coprecipitation from 60Co(NO3)2 solution with Al(OH)3 at pH 9.5. Then, the matrices retaining 137Cs and 60Co were washed and dried to be ready for use as cores of the sealed sources of the corresponding radionuclides. A calibrated amount of each matrix was separately packed in a stainless steel capsule in the form of round disc. After radiometric standardization and encapsulation, the sealed sources were submitted to quality control tests and finally checked radiometrically before release to the local market for calibration purposes of radiation measurement and identification instruments.