Advantages of Synchrotron for High Sensitivity Single Particle Analysis in Nuclear Forensics

Elucidating the origin and intended use of nuclear materials by high-sensitivity chemical and structural analysis remains a challenge. High intensity and brightness of advanced synchrotron sources, such as National Synchrotron Light Source II (NSLS-II), coupled with state-of-the-art sample manipulation and detection tools, present a great opportunity to advance the nuclear forensics toolkit. Work at Brookhaven National Laboratory in collaboration with Savannah River National Laboratoryutilizeshighresolutionsynchrotron-basedX-RayFluorescence(XRF)and X-ray Absorption Near Edge Spectroscopy (XANES) to study the elemental distribution and chemical structure of both surrogate and actinide containing engineered microparticles on particle-laden swipes and planchets produced via the THermally Evaporated Spray for Engineered Uniform particulateS (THESEUS) production platform. Using the Sub-micron Resolution X-ray Spectroscopy (SRX) beam line at NSLS-II, particle impurities synthesized via volumetric spike of impurity elements intofeedstocksolutionsof100ppmand1%Ni inCeO2and1%ThinU3O8 were measured.XANESanalysisdeterminedoxidationstatesofuraniumintwotypes of uranium-laden engineered microparticles and could discern between U3O8 and depleted uranyl oxalate despite consistent compositions observed via XRF. Synchrotron-based analysis of the engineered microparticles is complemented by parallel analysis via Automated Particle Analysis- Scanning Electron Microscopy (APA-SEM) and energy dispersive spectroscopy(EDS)-based elemental mapping at SRNL of microparticles produced via the same feedstock solutions as those on the particle-laden swipes measured at NSLS-II. This work provides high-resolution elemental mapping and chemical structure analyses of surrogate and actinide-laden engineered microparticles and enables a significant increase insensitivity of elemental analysis compared to utilization of only laboratory-based methods. Since synchrotron-based analysis is non-destructive, the samples can be utilized for subsequent isotopic analysis after synchrotron investigation, which is a unique and promising approach for micron size single particle analysis.