APPLICATION OF OPTICAL TECHNIQUES FOR ON-LINE MATERIALS ACCOUNTABILITY IN THE UREX SOLVENT EXTRACTION PROCESS

To support the demonstration of a more proliferation-resistant fuel processing plant, techniques and instrumentation to allow the real-time, on-line determination of special nuclear material concentrations in-process must be developed. Optical spectroscopy techniques, such as Ultraviolet and Visible Spectroscopy and Time Resolved Laser Induced Fluorescence Spectroscopy, are being evaluated to meet this need. These techniques are commonly used in the laboratory setting for the measurement of actinide concentrations in the ranges of interest to nuclear fuel recycling, and as non-nuclear techniques, show potential for use in high radiation environments for the direct measurement of constituent concentrations in process streams for the UREX solvent extraction process. Current work is focused on evaluating the impact of process chemistry on the detection and evaluation of uranium concentrations in process streams typical of the PUREX and UREX+ processes, with parallel studies using neptunium and plutonium to follow. The limits of quantization, including the impact of process chemistry (e.g. nitrate concentration, acid concentration) will be explored to determine suitability of these techniques for real-time interrogation of the process streams. As part of this work, the potential for applying the qualitative spectroscopic information to evaluate the chemical environment of the process stream will also be examined.