A green analytical approach for the direct non-destructive compositional analysis of (Th, U)O2 fuel pellets by the X-Ray Fluorescence technique using single universal calibration

Abstract

(Th, U)O₂-based mixed oxide (MOX) fuel is the proposed fuel for advanced heavy water reactors (AHWRs), which belong to the third stage of the three-stage Indian nuclear power programme. The composition of these types of mixed oxide fuels is one of the key parameters in chemical quality control. In the present work, a green analytical methodology has been developed utilizing the micro-X-Ray Fluorescence (micro-XRF) technique for the compositional analysis of these types of fuel pellets. Two different sample preparation methods have been proposed in this work. In Method 1, ≈500–600 μg powder sample scratched from the surface of the pellets was dispersed homogeneously in 1% TRITON solution, and a few hundred nanograms of the sample was deposited on a sample support for micro-XRF analysis. In Method 2, different portions of the pellet made contact with a Scotch tape sample support to transfer a few hundred nanograms of the sample, which was further used for micro-XRF measurements. Both of these methodologies do not require a cumbersome dissolution process in corrosive acids. Moreover, only a few hundred nanograms of the sample amount are sufficient for both methods. Using both sample preparation methodologies, 8 samples in the form of MOX fuel pellets were analyzed, and the results were compared with those obtained from the previously established total reflection X-ray fluorescence (TXRF) technique. The accuracy and precision obtained using Method 1 are 3.06% and 0.99%, respectively, and for Method 2, they are 3.79% and 2.96%, respectively. These methodologies require only a single calibration (or relative sensitivity measurement) for the analysis of all MOX fuel pellets regardless of the composition.