Feasibility Study of Isotope Ratio Analysis of Individual Uranium-Plutonium Mixed Oxide Particles with SIMS and ICP-MS

Isotope ratio analysis of nuclear materials in individual particles is of great importance for nuclear safeguards. Although secondary ion mass spectrometry (SIMS) and thermal ionization mass spectrometry (TIMS) are utilized for the analysisof individual uranium particles, few studies were conducted for the analysis of individual uranium-plutonium mixed oxide particles. In this study, we applied SIMS and inductively coupled plasma mass spectrometry (ICP-MS) to the isotope ratio analysis of individualU-Pu mixed oxide particles. In the analysis of individual U-Pu particles prepared from mixed solution of uranium and plutoniumstandard reference materials, accurate 235U/238U, 240Pu/239Pu and 242Pu/239Pu isotope ratios were obtained with both methods. However, accurate analysis of 241Pu/239Pu isotope ratio was impossible, due to the interference of the 241Am peak to the 241Pupeak. In addition, it was indicated that the interference of the 238UH peak to the 239Pu peak has a possibility to prevent accurateanalysis of plutonium isotope ratios. These problems would be avoided by a combination of ICP-MS and chemical separation ofuranium, plutonium and americium in individual U-Pu particles. KCI Citation Count: 2