Determination of 137Cs in irradiated uranium

137Cs in irradiated uranium sample was separated from the other fission products with 10 mg isotopic carrier by using connected columns of silica gel and Ionite C (zirconium phosphate), and was determined by γ-counting whereby the chemical yield was measured by precipitating and weighing of cesium tetraphenyl borate.Pass 10 ml of 2 N nitric acid solution of the sample with 10 mg Cs carrier through silica gel-Ionite C columns (volume: 3 ml each), and wash the column with 6 ml of 2 N HNO3. Disconnect the Ionite C column from the silica gel column, wash the Ionite C column with 15 ml of 2 N HNO3, and with 5ml of 6N HNO3. Elute Cs adsorbed on the Ionite C column with 10 N HNO3, evaporate the eluate and take up the residue with 1 N HNO3. Precipitate Cs three times as tetraphenyl borate. Weigh, and measure the γ-activity.The recovery test proved that the error was within ±3% and the decontamination factor of Cs from the other fission products at the column separation step alone was >2×104.