Solvent Extraction Studies in Miniature Centrifugal Contactors

Abstract

Solvent extraction IFuelreprocessinglCentrifugal contactors! Ruthenium jZirconiumThe contactor was also tested for application to the Civex and Thorex processes. SummaryA miniature short-residence-time centrifugal solvent extraction contactor and an eight-stage laboratory minibank of centrifugal contactors were used for testing the possibility of utilizing kinetic effects for improving the Separation of uranium from ruthenium and zirconium in the Purex process. Results of these tests showed that a small improvement found in ruthenium and zirconium decontamination in single-stage solvent extraction tests was lost in the multistage extraction tests -in fact, the extent of Saturation of the solvent by uranium, rather than the stage residence time, controlled the extent of ruthenium and zirconium extraction. In applying the centrifugal contactor to the Purex process, the primary advantages would be less radiolytic damage to the solvent, high throughput, reduced solvent inventory, and rapid attainment of steady-state operating conditions. The multistage mini contactor was also tested to determine the suitability of short-residence-time contactors for use with the Civex and Thorex processes and was found to be compatible with the requirements of these processes.

Instability of Some Nitrosylruthenium Compounds in Nitric Acid

“…Figure 5 shows the infrared spectra of the RuN0(N0 3 ) 3 and RUNOC13. Figure 6 shows the infrared spectra of Na 2 RuNO (N0 2 ) 4 OH • 2 H 2 Ο and RuNO (OH) 3 . The spectra show a strong absorption band in the vicinity of 1900 cm" 1 .…”

“…Nitrosylruthenium hydroxide (RuNO(OH) 3 ) was prepared by the method described by FLETCHER et al [8] and labeled with 103 Ru by neutron irradiation in the same reactor.…”

“…The extraction of ruthenium along with uranium and plutonium by TBP makes purification of uranium and plutonium from this element complicated [2 -5], High extractability of ruthenium in the reprocessing of spent nuclear fuel had been attributed to the nitrosylruthenium trinitrate(RuN0(N0 3 ) 3 ) in the solution of spent nuclear fuel [6][7].…”

“…The variety of behavior of ruthenium in nitric acid solution has been considered to arise from interconversion of ligands in the nitrosylruthenium complex to others with various velocities depending on external conditions [6]. The general formula of the nitrosylruthenium complex in nitric acid solution has been postulated as follows [3]: RUN0(N0 3 XC (N0 2 )y (OH) z (H 2 0) ( 5 3 -7-7-Γ ζ 2) . (1) The Ru-NO bond has been considered to be extraordinarily stable and difficult to break by substitution even by boiling in concentrated mineral acids [6].…”

Extraction and Stripping Tests of Engineering-Scale Centrifugal Contactor Cascade System for Spent Nuclear Fuel Reprocessing

“…In many studies, high mass transfer efficiencies of uranium have been demonstrated by using miniature centrifugal contactors. [10][11][12] Kuzunetsov et al showed that the mass transfer efficiency of uranium could reach 0.95 within 2 s/stage of the mixing time. 12) In our contactor design, the mixing time was around 2 s/stage for a 10 kg-HM/h flowsheet, so it has sufficient mixing time for uranium extraction.…”