Separation of Th-234 from Y-90

A relatively simple procedure has been developed for the determination of S r-90 in natural aqueous samples. The method consists mainly of a Fe(III)-hy droxide co precipitation step, followed by the separation of Y-90 with the mixture of yttrium-oxalate and yttrium-ammonium-oxalate salts. This method was tested using a large number of natural water samples and Th-234 contami nation was observed in the prepared yttrium samples. The analysis has there fore been extended to include the separation of thorium from yttrium, which is made by DOWEX-50W-X8 cation exchange resin and citric acid as chelating agent. The experience and results of this new method are discussed.