Isotopic analysis of single uranium and plutonium particles by chemical treatment and mass spectrometry

化学処理と質量分析の組合せによる単一ウラン及びプルトニウム粒子の同位体分析

篠永 妙子*; 江坂 文孝  ; 間柄 正明  ; Klose, D.*; Donohue, D.*

Shinonaga, Taeko*; Esaka, Fumitaka; Magara, Masaaki; Klose, D.*; Donohue, D.*

単一のウラン及びプルトニウム微粒子の同位体比分析を可能とする方法の開発を行った。電子顕微鏡による観察で選択した粒径数マイクロメートルの個々のウラン及びプルトニウム微粒子をそれぞれ溶解し、誘導結合プラズマ質量分析(ICPMS)及び表面電離型質量分析(TIMS)の2種類の方法により同位体比を分析した。その結果、両分析方法において保証値と一致した結果を得ることができた。以上より、単一微粒子の同位体比分析法として本法が有効であることが示された。

The isotopic composition of single uranium and plutonium particles was measured with an inductively coupled plasma mass spectrometer (ICP-MS) and a thermal ionization mass spectrometer (TIMS). The particles prepared on a carbon planchet were first analyzed with an energy dispersive X-ray spectrometer (EDX) attached to a scanning electron microscope (SEM) and then transferred on to a silicon wafer using a manipulator. The particle on the silicon wafer was dissolved with nitric acid and the isotopic ratios of U and Pu were measured with ICP-MS and TIMS. The results obtained by both methods showed good agreement with the certified values within the expected uncertainty. The measurement uncertainties obtained in this study were similar for both mass spectrometric methods. This study was performed to establish the method of particle analysis with SEM, EDX, the particle manipulation technique, and the measurement of isotope ratios of U and Pu in a single particle by mass spectrometry.