Analysis of plutonium isotope ratios in individual particles with ICP-MS for nuclear safeguards

Esaka, Fumitaka  ; Magara, Masaaki  ; Suzuki, Daisuke   ; Miyamoto, Yutaka   ; Lee, C. G.; Kimura, Takaumi 

In this study, inductively coupled plasma - mass spectrometry (ICP-MS) is applied to the analysis of plutonium isotope ratios in individual particles. Prior to the measurement, individual plutonium particles in samples are identified by using scanning electron microscope (SEM) and are transferred to each Si chip by a micro-manipulator attached to the SEM system. After removed from the SEM chamber, each particle is dissolved with HF-HNO solution for subsequent ICP-MS analysis. As a result, the Pu/Pu plutonium isotope ratios in individual particles with the diameter of around 1 micro-meter are successfully determined with good precision. A remaining subject to be solved is the mass interferences by co-existing elements such as americium. In order to remove the interferences, we are developing methods for chemical separation of americium and plutonium, based on anion exchange and capillary electrophoresis systems.