Investigation of Optical Spectroscopy Techniques for On-Line Materials Accountability in the Solvent Extraction Process
Abstract
The goal of this project is to evaluate the application of optical spectroscopy techniques to the on-line, real-time measurement of the actinide elements and “cold” chemicals in the process streams of a solvent extraction process. Based on the experience gained through this effort, engineers will have the information necessary to decide if these technologies should be advanced to the prototype stage and tested at the pilot plant level. Through the experimental work planned as part of this effort, researchers will also develop a better understanding of the chemical interactions of the actinide elements, providing additional data for the development of first-principles based models of the solvent extraction process, expanding current thermochemical databases for the solvent extraction process, particularly in the off-normal operating regimes.
Recent efforts have focused on reducing measurement uncertainty in the determination of uranium concentrations under process conditions and on measuring the nitrate concentration spectroscopically for process monitoring applications. Previous work exploring the application of UV-Vis spectroscopy in the UREX and PUREX separation processes demonstrated that the nitrate concentration in the sample significantly impacted the measured absorption spectra, requiring that any spectrometer system be calibrated for the expected process conditions. Deviations in nitrate concentration from the expected process chemistry result in an increase in uncertainty in the measured uranium concentration. Not only do these deviations in process chemistry increase measurement uncertainty, but they also reveal a systemic bias on the measurement that could be exploitable in a potential diversion scenario.