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

粒子移送及び二次イオン質量分析法を用いた個々の粒子中のウランマイナー同位体分析法

江坂 文孝  ; 江坂 木の実; Lee, C. G.; 間柄 正明  ; 桜井 聡 ; 臼田 重和; 渡部 和男

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

環境試料中の個々のウラン粒子のU/U及びU/U同位体比を分析する方法として、電子顕微鏡観察下での粒子移送と二次イオン質量分析法を組合せた方法を開発した。本法の有効性を確認するために、ウラン標準粒子とPb粒子を混合して作成した模擬環境試料の分析を行った。その結果、粒子移送によりPb分子イオンによる影響を排除することができ、認証値とよく一致したウラン同位体比測定結果が得られた。本法は実試料の分析にも適用され、その有効性が確認された。

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).