Enrichment processes

De-enrichment of HEU from approximately 93% to 3% can be accompHshed using the depleted tails from the original enrichment process. These tails contain on the average 0.20% U. The de-enrichment of 11 of HEU uses 32 t of tads, yielding approximately 33 t of fuel having an enrichment of 3% U. Producing the same amount of 3% enriched uranium from natural sources would requite approximately 180 t of natural uranium metal. Therefore, 1 t of HEU is equivalent to 180 t of natural uranium. 

G. F. Mailing and E. Von H.a]le,Merocfnamic Isotope Separation Processes for Cranium Enrichment Process Requirement, paper presented at the Symposium on New Advances ia Isotope Separation, Div. of Nuclear Chemistry and Technology, American Chemical Society, San Francisco, Calif., Aug. 1976 CCC-ND Report K/OM-2872, Oak Ridge Gaseous Diffusion Plant, Oak Ridge, Term., Oct. 7, 1976. 

Britton, L. G. 1996. Operating Atmospheric Vent Collection Headers Using Methane Gas Enrichment. Process Safety Progress, 15(4), 194-212. 

During the conversion process, the object is to create uranium hexafluoride (UF ), a highly corro-sh e substance that is gaseous at high temperatures, but is a white crystalline solid at lower temperatures. Uranium hexafluoride is easily transported in its ciystalline form to an enrichment facility (the step taken after conversion), but the gaseous form is well suited for the enrichment process, itself. First, the... 

Hawkesworth CJ, Kempton PD, Rogers NW, Ellam RM, van Calsteren PW (1990) Continental mantle lithosphere, and shallow level enrichment processes in the Earth s mantle. Earth Planet Sci Lett 96 256-... 

Practicable isotopic enrichment has the following prerequisites adequately short time for the enrichment process, acceptable asymptotic enrichment factor, and adequate accuracy for the estimation of the enrichment factor. (When total activity, rather than specific activity, is limiting, one must also pay attention to losses during enrichment.) For the argon and carbon enrichments referred to above, enrichment factors of about 100 and 500 were obtained within a week and a few hours, respectively and enrichment factors were deduced from direct observations of adjacent, stable isotopes. The 14C enrichment process provided extra dividends for AMS measurement the sample was implanted in an ideal form for the accelerator ion source, and it was spatially localized (depth) which gave added signal-to-noise enhancement. 

Solid-phase microextraction (SPME) is also a useful alternative to conventional sample cleanup with LLE or SPE. SPME is based on the enrichment of analytes by a partitioning process between a polymeric phase coated on a fused-silica fiber and its surrounding aqueous solution. SPME combines sample preparation in terms of extraction from a matrix of interfering compounds with an enrichment process in a single step. A method for the determination of metazachlor in wastewater samples is described in the literature [34]. In this study, SPME was shown to be a suitable and simple sample preparation method for the determination of metazachlor in wastewater by GC-AED. 

Uranium carbonates, 25 430-432 Uranium chlorides, 25 438-439 Uranium compounds, 25 421-434 handling, 17 529 Uranium dioxide, 25 422-423 Uranium-enrichment process gas centrifuge, 25 413-415 Uranium exploration, 25 398 URanium Extraction (UREX) process, 25 420... 

Ballhaus, C. Sylvester, P. 2001. Nobel metal enrichment processes in the Merenksy Reef, Bushveld Complex. Journal of Petrology, 41, 545-561. 

The GS enriching process is a counter-current gas-liquid extraction done at a pressure of 2000 kPa in a sieve tray tower with the upper half operating at 30 C and the lower at 130 C. ( 5) In the top half of the tower, feedwater extracts deuterium from the upflowing cold H2S, reaching a maximum at the centre of the tower. The recycled lean H2S entering the lower hot half of the tower strips deuterium from the water, which then leaves the system depleted in deuterium. A cascade of several stages is used to reach the desired feed concentration for the final water distillation or finishing unit. Transfer between cascades can be either by gas or liquid from the centre of the tower. 

Figure 11.3 is a starting point for comparing MS and IMS detectors in an overall screening system. Following the enrichment process described in Section 11.2.2,... 

Figure 10.17 Schematic representation of the systematic evolution of ligands by exponential (SELEX) enrichment process. (See the color version of this figure in Color Plates Section.)...

Figure 10.17 Schematic representation of the systematic evolution of ligands by exponential (SELEX) enrichment process.

As is well known, ammunition containing depleted uranium (DU) was used by NATO, for example, in the former Yugoslavia. To evaluate the origin of DU (enrichment process of natural uranium or reprocessing of exhausted nuclear fuel) it is necessary to directly detect the presence... 

Long-lived radionuclides occur at extremely low concentrations, especially in environmental samples, therefore several authors have proposed matrix separation and enrichment of the analytes before analysis.21,24,26,3 39 Radiochemical methods often require very careful and time consuming separation and enrichment processes and measurement procedures of a-, (3- and -emitting radioactive species at the trace and ultratrace level using conventional radioanalytical techniques 40-43 Trace/matrix separation, which is performed offline or online in order to avoid possible isobaric interferences, matrix effects and to reduce the detection limits for the determination of long-lived radionuclides, is also advantageous before ICP-MS measurements as the most widely applied mass spectrometric technique. 

UF6 ( hex ) is the only readily available uranium compound that is volatile at room temperature. It is a colorless solid that is used in the uranium enrichment process. It sublimes at room temperature without melting. UF6 is rapidly hydrolyzed by water and is a fluorinating agent. This latter property means that one must carefully choose the materials to contain UF6. 

For the LC separation, 10 ml of sample was injected through a loop. The LC flow-rate was 1000 pi min-1 and at the end of the enrichment process this was reduced to 100 pi min-1. The mobile phase composition was optimized to eliminate matrix polar compounds and elute the phthalates in a small fraction. 

Cell-enrichment processes not using fluorescent or magnetic technology are based on cell physicochemical properties, such as density, size, electrophoretic mobility, or surface composition (phenotype) (1). One of the earliest and still most commonly used methods is based on the use of centrifugal force to exploit density differences and deplete erythrocytes from whole blood. Further... 

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