Nuclear energy represents one of the strongercandidates to meet the worlds’ ever-growing energyneeds. However, the nuclear fuel cycle faces manychallenges; in particular improved methods formonitoring radioactive materials throughout the cycle areneeded to maintain proper safeguards and ensure safeand efficient processing of materials. Development ofmore effective, reliable, and fast methods for monitoringradioactive materials is integral to the continueddevelopment of the nuclear fuel cycle.The advancement of microfluidics and lab-on-a-chipdesigns has provided a pathway of experimentation thatutilizes volumes which are orders of magnitude less thanprevious techniques. For radioactive applications thebenefits of lower dose to workers and equipment, smallerfeedstock volumes, and less waste make these techniquesof significant interest. With these benefits come thecomplication of solution analysis, as conventionalspectroscopic techniques require much larger volumes.An example is Raman spectroscopy, which has been usedextensively for solution analysis; of key interest to thenuclear field is measurement of species such as actinidedioxocations, organic solvent components andcomplexants, inorganic oxo-anions (NO_3~-, CO_3~(2-), OH~-,SO_4~(2-), etc), and pH/acid concentration.Typical Raman probes require a minimum solutionvolume on the order of mLs in order to obtainquantifiable measurements of solution components,especially those with low concentrations. A new micro-Raman probe has been developed which significantlyreduces the focal region of the excitation beam andallows for the interrogation of reduced sample volumes.The micro-Raman probe focal region readily fits intomost microfluidic chip channels as well as micro flowcells.Instrument performance was tested on a variety ofsolution systems including a flowing stream of uranylnitrate in nitric acid. A micro-Raman probe was used tomeasure the uranyl nitrate and nitric acid sequentiallyinjected through the microfluidic cell. The application ofchemometric analysis was performed to quantify theuranyl, nitric acid, and total nitrate within the systembased on the Raman spectra. Probe performance formonitoring two-phase systems including complicationswith interfering species was also explored. Overall, thisnovel spectroscopic probe has successfully enabled theon-line analysis of a variety of streams on the microscale.This paper focuses on our current progress in on-line,real-time process monitoring. Advances in spectroscopictechnology and our analytical approach will be discussed.An overview of the successful application withinmicrofluidic systems will be discussed.
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