Sample preparation for actinide isotopic analysis using FIB-SEM

Abstract Capabilities to extract and analyse nanogram-scale uranium dioxide (UO 2 ) samples to allow spatial isotopic analysis were established by the development of techniques from wider literature. A Helios 5CX Focussed Ion Beam Scanning Electron Microscope (FIB-SEM) adapted for alpha-emitting radioactive material was used to extract samples of 2–80 ng from a depleted UO 2 pellet. These were analysed by Thermal Ionisation Mass Spectrometry (TIMS) and Triple Quadrupole Inductively Coupled Mass Spectrometry (ICP-QQQ-MS). TIMS produced measurements for 234 U, 235 U, 236 U, and 238 U weight-percent (wt%) with relative standard uncertainties (RSU) of between 0.26 and 11%. ICP-QQQ-MS measured the 235 U/ 238 U ratio with an RSU of 37.4%.