Multi-Isotope determination of uranium-rich material using accelerator mass spectrometry

Environmental detection of trace isotopes 233 U and 236 U are important forensic signatures for identifying uranium ore materials or tracking anthropogenic releases from weapons fallout or nuclear reprocessing. Currently, Accelerator Mass Spectrometry (AMS) is the only method sensitive enough to detect signatures of 233 U/U and 236 U/U at the natural level due to the molecular interferences of 232 ThH and 235 UH, respectively, often present in conventional mass spectrometry. In this work, we detail the AMS capabilities of actinides developed at the University of Notre Dame’s Nuclear Science Laboratory (NSL). For the first time in our laboratory, we have measured isotopic ratios of 236 U/U and explored additional signatures of 233 U and decay chain products 231 Pa and 230 Th in both natural ore material and two National Bureau of Standards samples. In this work we estimate a system sensitivity for 236 U/U of 1.4×10-11 and characterize the simultaneous detection of 233 U, 231 Pa, and 230 Th.