Determination of the isotopic ratio ~(234)U/~(238)U in liquid scintillation and environmental applications

摘要

We describe a procedure to measure the isotopic ratio ~(234)U/~(238)U in liquid samples. This method combines an extractive technique, liquid scintillation counting with α/β discrimination and a fit procedure of α ADC spectra. Its main advantages are: high detection efficiencies for α emissions, energy sensitivity, rapid and easy preparation of the samples. This makes the technique suitable for environmental survey. We tested the method on a wide set of NBS standards, considering ~(235)U enrichments up to 5% (the maximum value allowed for civil uses). Results on samples collected on field were validated by a comparison with ICP mass spectrometry.