A comparison of radiochemical methods for cesium-137 determination

The results are presented of a comparative study seeking an accurate and precise radiochemical method for 137Cs determination in burnup measurements. The methods taken up are chloroplatinate-precipitation (Method I), tetraphenylborate-precipitation (Method II), tetraphenylborate-extraction (Method III), potassium hexacyanocobalt(II) ferrate(II)-substitution (Method IV) and ion-exchange (Method V). A common sample, an aqueous solution obtained from dissolving irradiated uranium fuel and containing approximately 5μCi of 137Cs, was analyzed by seven analysts using the five methods. A statistical analysis of the results obtained (105 values in all) show that the expected precision, at the 0.05 probability level, of a single determination in non-rehearsed trials of each method are: Method I, ±3.0%; Method II, ±5.6%; Method III, ±5.3% Method IV, ±10.9%; Method V, ±4.2%. The accuracy follows the same pattern except Method III and Method IV. The advantages and disadvantages of the five methods are discussed from the standpoint of utilization in burnup measurements.