Separation and quantification of Sr-90 from ion-exchange resin radioactive waste: methods and techniques of analysis

摘要

Four methods for Sr-90 separation from spent ion-exchange resin samples were carried out, offering a useful methodology to achieve interferences free Sr-90 fractions. The four methods consist in resin sample decomposition, pre-treatment and selective separation of Sr-90 by using: (a) a single chromatographic extraction process, (b) double chromatographic extraction, (c) a single chromatographic extraction process followed in sequence by two precipitations, and (d) ion-exchange chromatography, followed by extraction chromatography and precipitation. Mineralization by microwave acid digestion and the four Sr-90 separation methods thoroughly presented are available. Data processing methods (adjustable modified efficiency tracing - a new improved approach for the efficiency tracing LSC technique, non-linear regression and alpha-beta discrimination) to obtain the activities values of alpha, beta-gamma, pure beta emitters and the evaluation of chemical recovery yield of strontium were presented. A discussion about activity assessment in Sr-90 purified fractions, providing a convincing argument to support the accuracy of the Sr-90 separation methods, is also offered.