Determination of trace elements in uranium oxide by Total Reflection X-ray Fluorescence spectrometry

A study on the applicability of Total Reflection X-ray Fluorescence for the determination of multielements in trace amounts in U3O8 matrix has been made. The calibration of the Total Reflection X-ray Fluorescence spectrometer and the validation of the method were done using multielement standards. The trace elements present in U3O8 standards and samples were determined after separating the U matrix by solvent extraction using tri-n-butyl phosphate and trioctyl phosphine oxide as extractants. From the aqueous phase the elements K, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, Br, Rb, Sr, Y, Zr, Pb and Ba, etc., were determined by Total Reflection X-ray Fluorescence using Ga as an internal standard. An intercomparison of the Total Reflection X-ray Fluorescence determined concentrations of the trace elements specific to nuclear fuel, e.g. Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn in U3O8 standards/samples with certified concentrations for these elements in U3O8 standards and Inductively Coupled Plasma Atomic Emission Spectroscopy determined concentrations in real U3O8 samples was also made. The method shows a precision and accuracy better than 5% (1σ) for most elements in concentration range of ng/mL with a sample size of 10 μL.