Year
2008
Abstract
Identification and quantification of specific alpha- and beta-emitting radionuclides in complex liquid matrices is highly challenging, and is typically accomplished through laborious wet chemical sample preparation and separations followed by analysis using a variety of detection methodologies (e.g., liquid scintillation, gas proportional counting, alpha energy analysis, mass spectrometry). Analytical results may take days or weeks to report. Chains of custody and sample security measures may also complicate or slow the analytical process. When an industrial process-scale plant requires the monitoring of specific radionuclides as an indication of the composition of its feed stream or of plant performance, radiochemical measurements must be fast, accurate, and reliable. Scientists at Pacific Northwest National Laboratory have assembled a fully automated prototype Process Monitor instrument capable of a variety of tasks: automated sampling directly from a feed stream, sample digestion / analyte redox adjustment, chemical separations, radiochemical detection and data analysis / reporting. The system is compact, its components are fluidically inter-linked, and analytical results could be immediately transmitted to on- or off-site locations. The development of a rapid radiochemical Process Monitor for 99Tc in Hanford tank waste processing streams, capable of performing several measurements per hour, will be discussed in detail. More recently, the automated platform was modified to perform measurements of 90Sr in Hanford tank waste simulant. The system exemplifies how automation could be integrated into reprocessing facilities to support international nuclear safeguards needs.