Latest improvements in isotopic uranium particle analysis by large geometry–secondary ion mass spectrometry for nuclear safeguards purposes

Abstract

Large geometry secondary ion mass spectrometry can be efficiently used to analyze uranium aerosol particles from dust samples in the search for undeclared nuclear activities. Automated sample screening measurements are followed by more precise and accurate microbeam measurements of both the major and minor uranium isotopes on selected individual particles. The quality of this work is essential in order to be able to draw valuable safeguards conclusions. This paper describes the latest developments that have been undertaken to enhance the detection limits and to reduce the uranium isotope measurement uncertainty. It includes improvements in the analytical protocol as well as in the instrument acquisition software and data reduction method. Recent useful yield measurements have been performed on uranium monodispersed particles using different primary bombardment conditions to compare to previously obtained data. Comparison of uranium isotope measurements when using pyrolytic graphite or silica planchets as a sample substrate will also be presented.

240Pu/239Pu isotopic ratio measurements in micrometric Pu and MOX particles using Secondary Ion Mass Spectrometry

“…The development of the Automated Particle Measurement software by Cameca [11,12] allowed the SIMS method to detect and locate U bearing-particles in the whole sample, like the FT-TIMS method. The implementation of the large geometry -SIMS (LG-SIMS) has further improved the performance of isotopic measurements thanks to the increase of the mass resolution (to separate ions of interest from interfering species) and to the use of several detectors for the simultaneous collection of ion beams (multi-collection) [13][14][15].…”