Direct isotope ratio analysis of individual uranium-plutonium mixed particles with various U/Pu ratios by thermal ionization mass spectrometry

Suzuki, Daisuke   ; Esaka, Fumitaka  ; Miyamoto, Yutaka   ; Magara, Masaaki  

Isotope ratios of uranium and plutonium in individual U-Pu mixed particles with various U/Pu ratios were determined by thermal ionization mass spectrometry with a continuous heating method without chemical separation. Prior to the measurements, micron-sized U-Pu mixed particles with U/Pu ratios of 1, 5, 10, 18 and 70 were produced by using certified reference materials CRM U-010 (1%U enriched, NBL) and SRM 947 (NBS) solutions. As a result of isotope ratio analysis, accurate values for U and Pu ratios, except for Pu/Pu, were successfully determined for the particles with all U/Pu ratios. Although some pre-treatment such as chemical separation would need for accurate determination of Pu/Pu isotope analysis, it was shown that this analytical technique has a potential of powerful tool for nuclear safeguards and forensics.