On-line analyzer for monitoring uranium and technetium in the vent of a gaseous diffusion plant

An automated electrochemical analyzer to provide continuous on-line measurement of volatile uranium and technetium compounds in the vents of a gaseous diffusion plant has been developed. The analyzer uses square wave polarography to measure uranium and technetium concentrations in an alkaline solution that has been used to scrub a known volume of the diffusion cascade vent gases. Uranium can be determined down to 0.12 ..mu..g/mL solution sensitivity (0.093 ..mu..g/L gas sensitivity at a flow rate of 4 L/min and a sampling time of 30 min), and technetium can be determined to concentrations of 0.018 ..mu..g/mL (0.014 ..mu..g/L). A high-speed polarographic analyzer, a personal computer, and a controllable sampling and reagent handling system were used to develop the automated analyzer. A three-electrode system consisting of a dropping mercury electrode, a platinum working electrode, and a silver-silver chloride reference electrode was used. The computer controls all polarographic operating parameters, sampling times, valve sequencing for solution flows, data acquisition, and reporting of results to the cascade control room. Software routines were developed for computer graphics, for system diagnostics and analytical program monitoring, for data storage, and to control sample monitoring to ensure long-term field reliability. The system will incorporate an alarm that ismore » sounded in the control room if concentrations of uranium or technetium reach action values. The analyzer is capable of continuous operation for 14 days without operator assistance since all reagents are self-contained and control sample data is transmitted for control room examination. Analytical results are more timely and efficient than previously used manual sampling and analysis procedures. 8 refs., 1 fig., 2 tabs.« less