Processing of monazite sands

For the past ten years, much effort has been expended by several research teams to develop an economic process for recovering thorium, rare earths and uranium from monazite sands. Recently, a process was developed at the Ames Laboratory which possessed many attractive features. The major disadvantage inherent to the process was the large cost for oxalic acid. The oxalic acid was used to precipitate rare earth and thorium oxalates from a sulfate and phosphate solution of these elements. The object of the oxalate precipitation was to separate the thorium and rare earths from uranium, sulfate and phosphate ions. Since this method for processing monazite sands was so attractive, concerted effort was made to discover a method whereby the oxalic acid could be recycled

Development of mandibular, hyoid and hypobranchial muscles in the zebrafish: homologies and evolution of these muscles within bony fishes and tetrapods

<p>Abstract</p> <p>Background</p> <p>During vertebrate head evolution, muscle changes accompanied radical modification of the skeleton. Recent studies have suggested that muscles and their innervation evolve less rapidly than cartilage. The freshwater teleostean zebrafish (<it>Danio rerio</it>) is the most studied actinopterygian model organism, and is sometimes taken to represent osteichthyans as a whole, which include bony fishes and tetrapods. Most work concerning zebrafish cranial muscles has focused on larval stages. We set out to describe the later development of zebrafish head muscles and compare muscle homologies across the Osteichthyes.</p> <p>Results</p> <p>We describe one new muscle and show that the number of mandibular, hyoid and hypobranchial muscles found in four day-old zebrafish larvae is similar to that found in the adult. However, the overall configuration and/or the number of divisions of these muscles change during development. For example, the undivided adductor mandibulae of early larvae gives rise to the adductor mandibulae sections A0, A1-OST, A2 and Aω, and the protractor hyoideus becomes divided into dorsal and ventral portions in adults. There is not always a correspondence between the ontogeny of these muscles in the zebrafish and their evolution within the Osteichthyes. All of the 13 mandibular, hyoid and hypobranchial muscles present in the adult zebrafish are found in at least some other living teleosts, and all except the protractor hyoideus are found in at least some extant non-teleost actinopterygians. Of these muscles, about a quarter (intermandibularis anterior, adductor mandibulae, sternohyoideus) are found in at least some living tetrapods, and a further quarter (levator arcus palatini, adductor arcus palatini, adductor operculi) in at least some extant sarcopterygian fish.</p> <p>Conclusion</p> <p>Although the zebrafish occupies a rather derived phylogenetic position within actinopterygians and even within teleosts, with respect to the mandibular, hyoid and hypobranchial muscles it seems justified to consider it an appropriate representative of these two groups. Among these muscles, the three with clear homologues in tetrapods and the further three identified in sarcopterygian fish are particularly appropriate for comparisons of results between the actinopterygian zebrafish and the sarcopterygians.</p

A PROCESS FOR THE RECOVERY OF URANIUM FROM NUCLEAR FUEL ELEMENTS USING FLUID-BED DRYING AND VOLATILITY TECHNIQUES

A process scheme for the recovery of uranium from fuel elements has been developed. The scheme combines continuous fluid-bed drying and fluoride volatility techniques after initial dissolution of the fuel element in the appropriate aqueous system, hence the designation ADF, Aqueous Dry Fluorination Process. The application of this process to the recovery of uranium from highly enriched, low uranium-zirconium alloy plate-type fuels is described. ln the process, the feed solution is sprayed horizontally through a two-fluid nozzle and is atomized directly in the heated fluidized bed. The spray droplets are dried on the fluidized particles and form a dense coating. Excessive particle growth was limited by the use of air attrition-jets inserted directly in the bed. Aqueous hydrofluoric acid solutions containing l.2 to 3.6 M zirconiuni, 0.007 to 0.03 M uranium, and free acid concentrations from 1 to about l0 M were successfully processed in a 6-in.-diameter Inconel fluid-bed spray dryer. Rates equivalent to about 3.l kg/hr of zirconium were achieved, 160 ml/min with the most concentrated feed solution. Experiments were successfully carried out from 240 to 450 deg C. A new design for a two-fluid nozzle was developed. Extensive work was done to identify the various zirconium fluoride compounds formed. The granular dryer product was subsequently fluorinated at temperatures to 600 deg C in fluid beds and to 700 deg C in static beds to remove the uranium as the volatile hexafluoride. About 90 to 95% uranium removal was consistently achieved near 600 deg C. The relatively low uranium recovery under these conditions is a disadvantage for the application to zirconium-base fuels. It was found necessary to resort to static beds and higher temperatures to achieve greater removal. Since the fluorine attack on nickel, the material of construction, is prohibitive at temperatures above 600 deg C, a disposable fluorinator concept for use with static beds is described. Results of corrosion studies are reported. A preliminary chemical flowsheet with a design capacity of 1l00 kg of uranium (93% enriched) annually is presented. (auth

Argonne National Laboratory Reports

The idea for this meeting evolved from interest expressed by members of the Chicago Section of the Electrochemical Society in convening a symposium on the development of high-energy secondary batteries. The relevance of this subject is evidenced by the several research programs that have been initiated recently in the United States and Europe to develop advanced batteries for use as energy storage devices on electric utility networks and as power sources for electric automobiles

Argonne National Laboratory Reports

From Summary: "The work described in this report is the application of this process to the recovery of uranium from highly enriched, low uranium-zirconium alloy plate-type fuels.