Age determination of uranium samples by inductively coupled plasma mass spectrometry using direct measurement and spectral deconvolution

Abstract

A simple and rapid method has been developed for the direct determination of the age (i.e. the production date) of uranium-containing nuclear materials by inductively coupled plasma mass spectrometry based on the measurement of the ²³⁰Th/²³⁴U radionuclide ratio. The concentration of the trace-level ²³⁰Th in the samples was measured directly without the need for prior chemical separation. The tailing of the highly abundant ²³⁸U peak, which is typically around 10 orders of magnitude higher than that of the ²³⁰Th signal, was eliminated by the mathematical deconvolution of the measured mass spectrum. The ²³⁰Th and ²³⁴U contents were quantified by isotope dilution method. The developed method was validated using reference materials of known production date.