Determination of trace impurities in advanced metallic nuclear fuels by inductively coupled plasma time-of-flight mass spectrometry (ICP-TOF-MS)

Abstract

Binary and/or ternary metallic alloys of uranium (U) and plutonium (Pu) with transition metals are considered to be promising fuels for fast breeder reactors due to their high fissile atom content, high breeding ratio with lower doubling time, dimensional stability at high burn-up and high thermal conductivity, etc. Hence, the development of new and promising analytical methodologies for the characterization of trace impurities in advanced metallic fuels is always appreciated. In the present work, a number of trace impurities viz., B, Ce, Cd, Co, Eu, Dy, Gd, Mn, Nd, Ni, Sm and Tb in U–Ti, U–Zr and U–Mo alloys were determined by inductively coupled plasma mass spectrometry (ICP-MS). Solvent extraction using tributylphosphate (TBP) in carbon tetrachloride (CCl₄) was used for the partial removal of matrix elements so as to reduce the matrix effect on these analytes during mass spectrometric analysis. The common analyte internal standard (CAIS) technique was refined and utilized to account for the effect of the remaining matrix elements. The proposed refined CAIS technique was validated by standard addition using synthetic samples and the analyte recoveries were found to be ≥92%. Real samples of U–Ti, U–Zr and U–Mo alloys were analyzed for trace elements and the relative standard deviations (RSDs) were found to be between 5 and 8%. Cross-validation of the proposed method was carried out by isotope dilution mass spectrometry (IDMS) and recovery studies employing gamma spectrometry. The method detection limit (MDL) lies in the range of 3–15 ng mL⁻¹.