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

An attempt to recover and purify 4.66 TBq(126Ci) 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.