Use of secondary ion mass spectrometry in nuclear forensic analysis for the characterization of plutonium and highly enriched uranium particles

The application of secondary ion mass spectrometry (SIMS) analysis is descr ibed for the characterization of plutonium and highly enriched uranium (HEU ) particles with a diameter to 10 mu m. Applying a method previously descri bed, particles of HEU could be detected in a scrap material, together with natural uranium. The isotopic composition of the particles was measured wit h a typical accuracy and precision of 0.5%. The spectrum of the trace eleme nts in the uranium particles was also recorded. From the results it was pos sible to deduce that the uranium oxide, as UO2, was produced via a pyrochem ical process. In a sample consisting of a mixture of three different specie s of particles, two of these were identified as plutonium particles. They w ere characterized according to their isotopic ratio 239/240 as well as to t heir dimension and shape. The results obtained by SIMS for the isotopic rat io were compared with those obtained analyzing the particles by Thermal Ion ization Mass Spectrometry (TIMS). The shape and dimensions were confirmed b y the analysis with Scanning Electron Microscopy (SEM). In both the cases t he results obtained by SIMS were in good agreement with those from TIMS and SEM.