A comparative study on determination of uranium and thorium in their mixed oxides by EDXRF using tube and radioisotope X‐ray sources

Abstract

Studies on the matrix effects of uranium and thorium on the determinations of each other in their mixed oxides using energy dispersive X‐ray fluorescence (EDXRF) spectrometry with tube and radioisotope excitations of U Lα and Th Lα are reported. An internal standard method for the determination of uranium and thorium in these mixed oxides is found suitable. Comparison of the analytical results of EDXRF determinations of uranium and thorium using tube and radioisotope excitation sources has been made. The analytical methodology involves preparation of mixed oxide calibration/sample mixtures of uranium and thorium oxides, mixing of internal standard yttrium in these mixtures, pelletizing the mixtures after thorough mixing and grinding using boric acid binder and measuring EDXRF spectra of the specimens thus prepared using Rh X‐ray tube as well as 109Cd radioisotope source. The samples were analyzed for uranium and thorium on the basis of the calibration plots obtained by plotting the intensity ratios of the analyte and internal standard characteristic X‐ray lines and their corresponding amount ratios. An average precision of 1.2% (1 s RSD) was observed for the determination of U and Th and the results deviated from the corresponding expected values by 3% on average. Due to the refractory nature of thorium oxide, comparatively more grinding time was required for thorium determinations. Copyright © 2011 John Wiley & Sons, Ltd.

Synchrotron‐induced EDXRF determination of uranium and thorium in mixed uranium–thorium oxide pellets

“…It can be seen that the precision observed in the present case for uranium determinations (0.3%, 1 σ ) is much better compared with our earlier reported values in similar case using laboratory source of excitation . Similarly, the deviation of the EDXRF determined results with the expected value calculated on the basis of preparation of these pellets is 0.9% that is far better compared with our earlier reported values . The data for thorium determinations are comparable with those of uranium determination (deviation = 1% and precision = 0.2%).…”

“…A live time of 300 s was used for spectrum measurement. The details of this instrument are described elsewhere . The spectrometer EX3600 TEC uses a Peltier‐cooled semiconductor premium Si PIN diode detector with a measured resolution of 155 eV at 5.9 keV (Mn Kα), whereas for synchrotron measurements, a silicon drift detector with a measured resolution of 138 eV at 5.9 keV (Mn Kα) was used.…”

“…Thus, methods giving accurate and precise composition are essential for the compositional certification of the fuel materials at fabrication as well as at final stage. Previously, we have reported development of analytical methods using laboratory‐based energy dispersive X‐ray fluorescence (EDXRF) for the determination of uranium and thorium in solution and solid samples . Although solution‐based methods are better in terms of specimen uniformity, they require dissolution of the (U,Th)O 2 fuel that is very cumbersome .…”