Particle isolation for analysis of uranium minor isotopes in individual particles by secondary ion mass spectrometry

Esaka, Fumitaka  ; Esaka, Konomi; Lee, C. G.; Magara, Masaaki  ; Sakurai, Satoshi ; Usuda, Shigekazu; Watanabe, Kazuo

A new technique to measure U/U and U/U isotope ratios for individual particles in safeguards environmental samples was developed, which was a combination of particle isolation under scanning electron microscope (SEM) and secondary ion mass spectrometry (SIMS). In order to verify the effectiveness of the technique, the U/U and U/U isotope ratios were measured for individual particles in a simulated environmental sample containing uranium standard (NIST CRM U010) and Pb metal particles. The deviations of the U/U and U/U isotope ratios from the certified values increased with increasing the signal intensity ratio of Pb to U, which was due to the interferences by Pb molecular ions. By the isolation of individual uranium particles prior to SIMS analysis, the interferences were eliminated. The effectiveness of the technique was also confirmed by the analysis of a real sample taken at a laboratory in Japan Atomic Energy Agency (JAEA).