PNNL

Abstract

Nuclear energy is a promising low-carbon energy candidate to meet the increased demand for green energy, where the integration of fuel recycling can have significant benefits on material usage and waste reduction. Utilizing in situ monitoring tools can provide ample opportunities to better control and safeguard nuclear material recycle processes while also offering knowledge and insight into real time solution properties. The simultaneous measurement of analytical targets in multiple process locations can enable real-time mass balance and material accountancy calculations. This is demonstrated here with a mass balance study of Nd3+ on a countercurrent aqueous/organic metal extraction within a single centrifugal contactor. The Nd3+ concentration was simultaneously monitored at the inlets and outlets of both aqueous and organic phases using a visible absorbance detector that allowed for simultaneous measurement of up to six locations. The Nd3+ concentration was calculated using chemical data science algorithms, where model training sets were collected on a single track of the detector. Discussion includes addressing the challenges of using a model collected on a single track and applying it as a model across the other tracks on the detector. Each track of the detector corresponds to one measurement location on the contactor. The difference in the integrated moles of Nd3+ between the inlet and outlet at the end of the experiment was near zero, indicating that the mass balance of this experiment was maintained. Overall, the on-line spectroscopic monitoring was able to follow changing solution conditions and accurately measured the concentration of Nd3+ in different locations within the contactor system.