A combined cesium-strontium extraction/recovery process

A new solvent extraction process for the simultaneous extraction of cesium and strontium from acidic nitrate media is described. This process uses a solvent formulation comprised of 0.05 M di-t-butylcyclohexano-18-crown-6 (DtBuCH18C6), 0.1 M Crown 100{prime} (a proprietary, cesium-selective derivative of dibenzo-18-crown-6), 1.2 M tributyl phosphate (TBP), and 5% (v/v) lauryl nitrile in an isoparaffinic hydrocarbon diluent. Distribution ratios for cesium and strontium from 4 M nitric acid are 4.13 and 3.46, respectively. A benchtop batch countercurrent extraction experiment indicates that >98% of the cesium and strontium initially present in the feed solution can be removed in only four extraction stages. Through proper choice of extraction and strip conditions, extracted cesium and strontium can be recovered either together or individually

Uptake of actinides and other ions by Diphosil, a new silica-based chelating ion exchange resin

After adsorption of actinides on a phosphonic acid resin, it may be desirable to leave the actinides on the resin. It may be preferable that the polymeric resin matrix be replaced by an inorganic material, in order to prevent formation of radiolytic gases from the organic polymer. A new version of the Diphonix resin has been prepared, where the chelating diphosphonic acid groups are grafted to a silica support. This material is called Diphosil, for Diphonix on silica. This paper reports some results on equilibrium and kinetics of uptake of a number of actinide species and other metal ions of nuclear, environmental, or hydrometallurgical interest by Diphosil

TUCS: A new class of aqueous complexing agents for use in solvent extraction processes

The 1-hydroxyethyl-1,1-diphosphonic (HEDPA) and vinylidene-1,1-disphosphonic (VDPA) acids have been studied as stripping agents for Am, Pu, and U from TRUEX process solvent (0.2 M CMPO-1.2 M TBP-dodecane). Both disphosphonic acids have been shown to be highly effective stripping agents using pristine process solvent as well as radiolytically degraded solvent. The actinide-HEDPA and -VDPA complexes are more soluble than the corresponding oxalate complexes and are readily destroyed by metal-catalyzed H{sub 2}O{sub 2}. 12 refs., 4 figs., 2 tabs

Statistical mechanics of two-dimensional vortices and stellar systems

The formation of large-scale vortices is an intriguing phenomenon in two-dimensional turbulence. Such organization is observed in large-scale oceanic or atmospheric flows, and can be reproduced in laboratory experiments and numerical simulations. A general explanation of this organization was first proposed by Onsager (1949) by considering the statistical mechanics for a set of point vortices in two-dimensional hydrodynamics. Similarly, the structure and the organization of stellar systems (globular clusters, elliptical galaxies,...) in astrophysics can be understood by developing a statistical mechanics for a system of particles in gravitational interaction as initiated by Chandrasekhar (1942). These statistical mechanics turn out to be relatively similar and present the same difficulties due to the unshielded long-range nature of the interaction. This analogy concerns not only the equilibrium states, i.e. the formation of large-scale structures, but also the relaxation towards equilibrium and the statistics of fluctuations. We will discuss these analogies in detail and also point out the specificities of each system.Comment: Chapter of the forthcoming "Lecture Notes in Physics" volume: ``Dynamics and Thermodynamics of Systems with Long Range Interactions'', T. Dauxois, S. Ruffo, E. Arimondo, M. Wilkens Eds., Lecture Notes in Physics Vol. 602, Springer (2002

Process for the extraction of strontium from acidic solutions

The invention is a process for selectively extracting strontium values from aqueous nitric acid waste solutions containing these and other fission product values. The extractant solution is a macrocyclic polyether in an aliphatic hydrocarbon diluent containing a phase modifier. The process will selectively extract strontium values from nitric acid solutions which are up to 6 molar in nitric acid

Inductively coupled plasma-atomic emission spectrometry (ICP-AES) in support of nuclear waste management. [HHDECMP (hexyl hexyl-N,N diethylcarbamolymethylphosphonate) and n-octyl(phenyl)-N,N diisobutylcarbamoylmethylphosphine oxide]

Simulated complex nuclear waste solutions are characterized by Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AEC). The system uses and ICP source focused on both a polychromator and a computer-controlled scanning monochromator for intensity measurements. This instrumentation allows for simultaneous and sequential measurements of liquid extraction distribution coefficients needed in the development of process flow sheets for component separations. A large number of elements are determined rapidly with adequate sensitivity and accuracy. The focus of this investigation centers on the analysis of nuclear fission products. 13 references, 13 tables

Extraction chromatography: Progress and opportunities

Extraction chromatography provides a simple and effective method for the analytical and preparative-scale separation of a variety of metal ions. Recent advances in extractant design, particularly the development of extractants capable of metal ion recognition or of strong complex formation in highly acidic media, have significantly improved the utility of the technique. Advances in support design, most notably the introduction of functionalized supports to enhance metal ion retention, promise to yield further improvements. Column instability remains a significant obstacle, however, to the process-scale application of extraction chromatography. 79 refs