Determination of mass transfer coefficients of 99Tc(VII) in forward and backward transport in PUREX-relevant systems by using analytical ultracentrifugation
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R. Ludwig
The lack of published data on the extraction kinetics of Tc(VII) in the system U(VI)/HNO3//TBP/dodecane prompted us to investigate its transport behaviour in detail. The aim was to improve the U(VI)/Tc(VII) separation in the PUREX process. We choose the method of analytical ultracentrifugation to determine the concentration gradient profile, the initial flux density and the integral mass transport for both sides of the unstirred liquid-liquid interface as well as the overall mass transfer coefficients as a function of Tc(VII)-, U(VI)-concentrations and temperature from time-dependent changes of the refractive index gradients. The results were supplemented by comparing the experimental with calculated concentration profiles, obtained by modeling a diffusion-limited extraction process. In some of the investigated systems, the transport at the interface is reaction-limited after phase contact. The determined values of Jmax, I, and α are discussed in terms of the extraction conditions.
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Artikel in diesem Heft
- Luminescence study on solvation of americium(III), curium(III) and several lanthanide(III) ions in nonaqueous and binary mixed solvents
- Isotope correlations for determining the isotopic composition of plutonium
- Chemical analysis of transuranium nuclides in the uranium solution of the JCO criticality accident
- Differential pulse voltammetric determination of U(VI)-Tc(VII) and U(VI)-Cr(VI) in alkaline solutions
- Radiocesium removal from high level liquid waste and immobilisation in sodium silicotitanate for geological disposal
- Hot test of partitioning strontium from high-level liquid waste (HLLW) by dicyclohexano-18crown-6 (DCH18C6)
- Study of Ru released under accidental conditions by overheated nuclear fuel: the emission of Ru and U
- Evaluation of resonance ionization mass spectrometry for the determination of 135Cs/137Cs isotope ratios in low-level samples
- Determination of mass transfer coefficients of 99Tc(VII) in forward and backward transport in PUREX-relevant systems by using analytical ultracentrifugation
- Evaluation of the natural and man-made radioactivity levels around the Egyptian nuclear facilities
