Development of an analytical methodology for the determination of trace metal constituents in U-Zr alloy by ICP-AES

摘要

Since uranium-zirconium (U-Zr) alloys are one of the advanced fuels for future fast reactors, it is desirable to develop a method for the determination of trace constituents in U-Zr alloys as an integral part of chemical quality control of nuclear materials. A methodology was developed involving the simultaneous and selective extraction of U and Zr into the organic phase containing 30% tributyl phosphate (TBP)CCl _4, followed by the analysis of the raffinate for trace metallic constituents by inductively coupled plasma atomic emission spectrometry. The extraction profiles of U and Zr at various feed nitric acid concentrations revealed that 7M HNO 3 was the optimum feed acidity for the simultaneous extraction of U and Zr using 30% TBP-CCl _4 as the organic phase. Due to the emission-rich spectra of U and Zr, a systematic study on the spectral interferences of U and Zr on the analytes of interest was carried out which revealed that 10 μg/mL of U and 1000 ug/mL of Zr can be tolerated by the specified analytical wavelengths for the trace level determination of these analytes. Five sequential extractions of 30% TBP-CCl _4 were found to be sufficient to bring down the residual matrix concentration in the raffinate within tolerable limits. The methodology developed was validated using synthetic samples and found to be satisfactory for the 16 analytes of interest (Al, B, Cd, Co, Cr, Cu, Dy, Eu, Gd, Fe, Mn, Na, Ni, Sm, and Zn), including common impurities and rare earth elements (REEs), even at trace levels.