A rapid method for measuring strontium-90 activity in crops in China

With historical nuclear explosion and accidents, a large number of radionuclides such as fission product strontium have been released in the atmosphere. Due to its long half-life of about 28.5 years, it still exists in the environment and is likely to be found in some plants. A rapid method for measuring Sr⁹⁰ activity in crop ashes is presented. Liquid scintillation counting, combined with ion exchange columns 4', 4''(5'')-di-t-butylcyclohexane-18-crown-6, is used to determine the activity of Sr⁹⁰ in crops. The yields of chemical procedure are quantified using gravimetric analysis. The conventional method that uses ion-exchange resin with HDEHP could not completely remove all the bismuth when comparatively large lead and bismuth exist in the samples. This is overcome by the rapid method. The chemical yield of this method is about 60% and the MDA for Sr⁹⁰ is found to be 2.32 Bq/kg. The whole procedure together with using spectrum analysis to determine the activity only takes about one day, which is really a large improvement compared with the conventional method. A modified conventional method is also described here to verify the value of the rapid one. These 2 methods can meet different needs of daily monitoring and emergency situation. (authors)