Nuclear extract applications

Polarized light photomicrographs were taken of the green and calcined cokes, as well as their corresponding test graphites. The untreated extract cokes are characterized by very small amsotropic domains on the order of 3 microns or less. This type of optical structure is believed to be highly desirable for nuclear graphite applications. 

Erlinger, C.V. 1998. Towards a physical interpretation of third phase formation in liquid-liquid extraction. Application to the DIAMEX process for the treatment of high radioactive nuclear wastes. Thesis. University Paris XI, Paris. 

The chemistry of heterogeneous systems is far from restricted to nuclear technological applications. In heterogeneous catalysis, corrosion science, surface polymerization, biochemistry and many industrial applications such as liquid-liquid extraction, interfacial processes are of vital importance. In nuclear technological applications, the presence of ionizing radiation increases the complexity further. 

An interesting possible further extension is the functionalization of bispidine ligands with hydrophobic groups, for example, for metal ion selective extractions (69, 339). biopolymers for nuclear medicinal applications (340), solids for heterogeneous catalysis and sensors, or additional coordination sites for the synthesis of heterodinuclear complexes with applications in biomimetic chemistry, catalysis, and as luminescence sensors. There is a variety of possible sites for ligand modification. Of particular interest is the C9 position, which has been selectively and stereospecifically reduced to an alcohol (190), and the two hydrolyzed C1,C5 ester groups (167). 

Retinoic acid receptors (RARs) have been detected m nuclear extracts from various cell types on the basis of their ability to bind radiolabeled retinoic acid (1 3). Prior to the isolation of RAR cDNAs in 1987 (4,5), biochemical evidence for the existence of nuclear retinoic-acid binding proteins distinct from cytoplasmic CRABP had been obtained (1). The techniques used in these experiments can be used to study the biochemical properties of the RARs and may also be applicable to the study of the related receptors known as RXRs, which bind 9-cis retinoic acid with high affinity (6). 

Large efforts were given to assess compatibility of refractory alloys with liquid Li in space nuclear power applications. The compatibility issue has commonality with that of V-alloys with liquid Li. Those alloys which easily oxidize may have the benefit of using Li as a coolant because Li may remove impurity O in the alloys. However, high O level in the matrix of the refractory alloys may induce reduction corrosion [75]. Addition of O getters such as Hf, Zr, or Y were recommended for Nb-alloys [76]. Corrosion in liquid Li proceeds by dissolution of elements followed by mass transfer and impurity pick-up/extraction. Both processes are highly influenced by the circulation condition (delta T and flow distribution) and impurity levels of both Li and the alloy being tested. 

SAIC provided much of the data used in this book from its proprietary files of previously analyzed and selected information. Since these data were primarily from the nuclear power industry, a literature search and industry survey described in Chapter 4 were conducted to locate other sources of data specific to the process equipment types in the CCPS Taxonomy. Candidate data resources identified through this effort were reviewed, and the appropriate ones were selected. Applicable failure rate data were extracted from them for the CCPS Generic Failure Rate Data Base. The resources that provided failure information are listed in Table 5.1 with data reference numbers used in the data tables to show where the data originated. 

Depleted Uranium. In the natural state U is a mixt of isotopes from which two, U23s and U238> are extracted for use in nuclear reactors and weapons. What remains after the extraction is known as depleted uranium which now exists in large quantities and for which few uses have so far been found. One property of U is its high d -it is heavier than Pb — and this has led to the investigation of its military applications... 

Before leaving ionic liquids it is worth mentioning their potential value in separation processes. Organic solvents are frequently used in multiphase extraction processes and pose the same problems in terms of VOC containment and recovery as they do in syntheses, hence ionic liquids could offer a more benign alternative. Interesting applications along this line which have been studied include separation of spent nuclear fuel from other nuclear waste and extraction of the antibiotic erythromycin-A. 

Commercial-scale application of solvents coming under the category of neutral reagents is largely found as applied to the nuclear industry materials, as in example, for the separation and refining of uranium, plutonium, thorium, zirconium, and niobium. A process flowsheet for extracting niobium and tantalum from various resources is shown in Figure 5.23. It will... 

One of the more important considerations in determining the end use of synthetic graphite is its contamination with metallic components Metals such as iron, vanadium, and especially in nuclear applications, boron are deleterious to the performance of graphite Table 3 presented the extraction yields of NMP-soluble material for three bituminous coals. For these coals, mineral matter and insoluble coal residue were separated from the extract by simple filtration through 1-2 pm filter paper fable 13 lists the high-temperature ash content in the dry coal, and in their corresponding NMP-insoluble and NMP-soluble products. The reduced ash content of the extract is typically between 0.1 to 0.3 wt% using traditional filtration techniques for the small-scaled extraction experiments... 

Extraction of Spectral Information from a Short-Time Signal Using Filter-Diagonalization Recent Developments and Applications to Semiclassical Reaction Dynamics and Nuclear Magnetic Resonance Signals. 

Spectroscopic applications usually require us to go beyond single-point electronic energy calculations or structure optimizations. Scans of the potential energy hypersurface or at least Taylor expansions around stationary points are needed to extract nuclear dynamics information. If spectral intensity information is required, dipole moment or polarizability hypersurfaces [202] have to be developed as well. If multiple relevant minima exist on the potential energy hyper surface, efficient methods to explore them are needed [203, 204],... 

A recent and extremely important development lies in the application of the technique of liquid extraction to metallurgical processes. The successful development of methods for the purification of uranium fuel and for the recovery of spent fuel elements in the nuclear power industry by extraction methods, mainly based on packed, including pulsed, columns as discussed in Section 13.5 has led to their application to other metallurgical processes. Of these, the recovery of copper from acid leach liquors and subsequent electro-winning from these liquors is the most extensive, although further applications to nickel and other metals are being developed. In many of these processes, some form of chemical complex is formed between the solute and the solvent so that the kinetics of the process become important. The extraction operation may be either a physical operation, as discussed previously, or a chemical operation. Chemical operations have been classified by Hanson(1) as follows ... 

The extraction of deuterium from natural water feed forms an excellent case study of the application of large scale distillation and exchange distillation to isotope separation. The principal historical demand for deuterium has been as heavy water, D20, for use in certain nuclear reactors. Deuterium is an excellent neutron moderator, and more importantly, it has a low absorption cross section for slow neutrons. Therefore a reactor moderated and cooled with D20 can be fueled with natural uranium thus avoiding the problems of uranium isotope enrichment. This was the... 

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