Spectroscopic monitoring of spent nuclear fuel reprocessing streams: an evaluation of spent fuel solutionsviaRaman, visible, and near-infrared spectroscopy

Abstract

The potential of using optical spectroscopic techniques, such as Raman and visible/near infrared (Vis/NIR), for on-line process control and special nuclear materials accountability applications at a spent nuclear fuel reprocessing facility was evaluated. The availability of on-line, real-time techniques that directly measure process concentrations of nuclear materials will enhance the performance and proliferation resistance of the solvent extraction processes. Further, on-line monitoring of radiochemical streams will also improve reprocessing plant operation and safety. This paper reviews the current state of development of the spectroscopic on-line monitoring techniques for such solutions. To further examine the applicability of optical spectroscopy for this application, segments of a spent nuclear fuel, with approximate burn-up values of 70 MW d/kg M, were dissolved in concentrated nitric acid and adjusted to varying final concentrations of HNO 3 . The resulting spent fuel solutions were batch-contacted with tributyl phosphate/n-dodecane organic solvent. The feed and equilibrium aqueous and loaded organic solutions were subjected to optical measurements. The obtained spectra showed the presence of quantifiable Raman bands due to NO 3 − and UO 2 2+ and Vis/NIR bands due to multiple species of Pu(IV), Pu(VI), Np(V), the Np(V)-U(VI) cation-cation complex, and Nd(III) in fuel solutions. This result justifies spectroscopic techniques as a promising methodology for monitoring spent fuel processing solutions in real-time. The fuel solution was quantitatively evaluated based on spectroscopic measurements and was compared to inductively coupled plasma-mass spectroscopy analysis and Oak Ridge Isotope Generator (ORIGEN)-based estimates.

Plutonium (IV) Quantification in Technologically Relevant Media Using Potentiometric Sensor Array

“…The RMSEP values for plutonium The same samples were also measured with a UV-Vis-NIR spectrometer. The observed spectral shapes were similar to those reported in the literature [8]. The same 20-fold random split cross-validation procedure returned an average RMSEP of 6.1 mg/L of plutonium (compared to 3.9 mg/L by multisensor array).…”

“…In recent years, a novel approach towards analysis of PUREX process streams has emerged. It is based on the use of modern fiber optic probe UV-Vis-NIR and Raman spectrometers combined with chemometric data processing [4][5][6][7][8]. It was shown to be applicable for on-line determination of uranium, plutonium, nitric acid and lanthanides [9][10][11][12][13].…”

Detection and identification of solids, surfaces, and solutions of uranium using vibrational spectroscopy

“…Formation of the [UO 2 (NO 3 )] + complex results in a simple spectra with a band centered at ~870 cm −1 [160]. When the nitrate to uranyl ratio increases, the formation of nitrate species causes the valence electron from ${\text{NO}}_3^{2-}$ to shift to ${\text{UO}}_2^{2+}$.…”

Electrochemistry and Spectroelectrochemistry of the Pu (III/IV) and (IV/VI) Couples in Nitric Acid Systems

“…Waste concerns can be alleviated by closing the fuel cycle and recycling used nuclear fuel . The follow‐on safeguards and safety concerns can then be alleviated by introducing on‐line real‐time monitoring throughout the processing scheme for recycling .…”