A highly precise micro-analytical XRF method for compositional characterization of fast breeder reactor fuels

Abstract

Accurate and precise determination of plutonium and uranium in Fast Breeder Reactor (FBR) fuels is one of the most important steps in the chemical quality control of these fuels. Along with high precision, minimization of radioanalytical waste generated during measurements is of equal importance. Till date, routine wet radioanalytical techniques used for this purpose produce a lot of radioactive waste which needed an extensive recovery procedure. This paper describes a novel and simple micro-analytical method for determination of the Pu percentage with respect to uranium in fast reactor nuclear fuels, both carbide and oxide, using micro X-Ray Fluorescence (μ-XRF) spectrometry. The developed methodology requires ∼200 ng of sample for analysis and the radioactivity in such sample specimens is below 500 becquerel. Therefore, these sample specimens could be isolated with a layer of Scotch tape and analyzed. The detection limit for U and Pu, obtained using the developed methodology was ∼60–64 ng mL⁻¹. Using a single calibration plot, the Pu percentage in fuel samples could be determined in the entire concentration range from 10 to 90% for both the fuels. The average precision obtained was 0.23% (1σ; n = 3) for samples having a (U/Pu) concentration of <100 μg mL⁻¹ in the final aliquot (sample deposition volume was 2 μL) and the deviations from the expected results (calculated on the basis of sample preparation) were within 0.21%. The developed methodology minimizes radiological waste to a great extent and reduces radiotoxic burden on the environment. Due to high precision and accuracy of the obtained analytical results, this micro-analytical methodology can evolve as a potential alternative to wet chemical methods used routinely.