The development of uranium isotopic ratio analysis for uranium‐bearing particles by using oxygen flooding technique with SIMS

Abstract

The isotopic ratio of uranium‐bearing particles could be used to detect undeclared nuclear activities. How to strengthen the analyzing ability of secondary ion mass spectrometry (SIMS) was important to get certain information. For this purpose, the oxygen flooding technique was studied to enhance the ability of measuring isotopic ratio in uranium particles. The influence of oxygen flooding on the sensitivity of U+, UO+ and UO2+ was checked by using uranium metal and uranium particle (CRM U200) samples. The major and minor isotopic ratios of uranium bearing particles were measured by U+, UO+ and UO2+. The result shows that the use of oxygen flooding technique has no effect on the sensitivity of U+ and the isotopic ratio 234U/238U and 235U/238U. However, the intensity of UO+ and UO2+ increased several times with the oxygen flooding. Besides, the accuracy and precision of major isotopic ratio measured by uranium–oxygen ions were better than that measured by U+. For the minor isotopic ratio (234U/238U), it cannot be measured by uranium–oxygen ions because of the interference of polyatomic ions on carbon mat. After changing sample mat, for example, silicon mat, it can be measured by UO+ and get better results with oxygen flooding technique. Copyright © 2014 John Wiley & Sons, Ltd.