Simple determination of ⁹⁰Sr in highly radioactive liquid waste by alkaline precipitation separation/liquid scintillation counting technique

An analytical method with a liquid scintillation counting technique for the determination of ⁹⁰Sr in the presence of other elements was developed by deriving a calculation formula to remove their influences. The analysis of ⁹⁰Sr has been performed using the radioactive equilibrium of a generation process of ⁹⁰Y with ⁹⁰Sr separated from a sample. In this study, a new disintegration calculating formula that enable us to remove the influences by the coexistence nuclides to analyze ⁹⁰Sr in highly radioactive liquid wastes of spent-fuel reprocessing plants was derived, and the formula was validated by experimental approaches. It was found that ⁹⁰Sr could be analyzed without any influences when a sample contained nuclides that had a long half life, and the radioactive equilibrium was small enough compared to the generation of ⁹⁰Y. The relative standard deviation of the analysis by the proposed method was equal to, or less than, 3%.