Recovery and purification of 4.66 TBq(126Ci) of 137Cs from a 20-year-old spent sealed source.

Abstract An attempt to recover and purify 4.66 TBq(126 Ci) of 137 Cs as solution from a 20-year-old doubly encapsulated sealed source containing 137 CsCl was made successfully. The primary capsule was first cut open to retrieve the secondary capsule. The top end of the secondary SS capsule was then cut to render it as an open cylinder and the 137 CsCl pellet inside was dissolved in small aliquots of water. Each aliquot of the 137 CsCl solution was dispensed into glass vials, sealed, assayed and stored. Barium formed during the radioactive decay of 137 Cs was removed by carbonate precipitation. Chloride was removed by heating with HNO 3 and evaporation. About 91.8% of the total activity could be recovered and used subsequently for making brachytherapy sources.