Uranium fluorides

Magnesium fluoride is a by-product of the manufacture of metallic beryllium and uranium. The beryllium or uranium fluorides are intimately mixed with magnesium metal in magnesium fluoride-lined cmcibles. On heating, a Thermite-type reaction takes place to yield the desired metal and Mgp2 (13). Part of the magnesium fluoride produced in this reaction is then used as a lining for the cmcibles used in the process. 

The rate (kinetics) and the completeness (fraction dissolved) of oxide fuel dissolution is an inverse function of fuel bum-up (16—18). This phenomenon becomes a significant concern in the dissolution of high bum-up MO fuels (19). The insoluble soHds are removed from the dissolver solution by either filtration or centrifugation prior to solvent extraction. Both financial considerations and the need for safeguards make accounting for the fissile content of the insoluble soHds an important challenge for the commercial reprocessor. If hydrofluoric acid is required to assist in the dissolution, the excess fluoride ion must be complexed with aluminum nitrate to minimize corrosion to the stainless steel used throughout the facility. Also, uranium fluoride complexes are inextractable and formation of them needs to be prevented. 

Fluorides. Uranium fluorides play an important role in the nuclear fuel cycle as well as in the production of uranium metal. The dark purple UF [13775-06-9] has been prepared by two different methods neither of which neither have been improved. The first involves a direct reaction of UF [10049-14-6] and uranium metal under elevated temperatures, while the second consists of the reduction of UF [10049-14-6] by UH [13598-56-6]. The local coordination environment of uranium in the trifluoride is pentacapped trigonal prismatic with an 11-coordinate uranium atom. The trifluoride is... 

The following reactions can be considered for the preparation of uranium fluorides (UF4 or UF6) starting from urania (U02) at a temperature of 500 °C ... 

Figure 4.24 Reactor for uranium fluoride reduction with calcium.

B) R. DeWitt, Uranium Hexafluoride A Survey of the Physico-Chemical Properties , GAT-280, Goodyear Atomic Corp, Portsmouth, Contract AT<33-2>1 (1960) C) L.S. Allen, A Parametric Survey of Criticality-Limited Fast Reactors Employing Uranium Fluoride Fuels , TR32-198, Jet Propulsion Lab, Contract NAS-7-100 (1962) D) C.A. Geffen et al, Assessment of the Risk of Transporting Uranium Hexafluoride by Truck and Train , Battelle, Richland, Contract EY-76-C-06-1830 (1978)... 

Uranium hexafluoride is probably the most interesting of the uranium fluorides. Under ordinary conditions, it is a dense, white solid with a vapor pressure of about 120 hull ai room temperature. It can readily be sublimed or distilled, and it is by far the most volatile uranium compound known. Despite its high molecular weight, gaseous UFg is almost a perfect gas, and many of the properties of the vapor can be predicted from kinetic theory. 

Finally, a question obviously arises at the end of this chapter on oxyfluorinated open frameworks. Does open frameworks exist with only fluoride anions The recent discovery of two-dimensional uranium fluorides templated by alkyldiamines by O Hare et al. [81,82] is a first answer to the question, and no doubt that in a few years, the discovery of purely fluorinated solids with an open framework will be claimed. 

Finally, some DOE sites also have stored hexavalent uranium fluoride (UFs). The approach to stabilize this compound is to calcine it to form stable uranium oxide. There is no study reported in the literature on treatment of fluorides using a CBPC matrix, but considering that fluroapatites are stable minerals, they should be applicable to stabilization of actinide compounds. 

An example of a common situation that leads to greater radiation exposure levels than would be expected occurs with some uranium compounds. Depleted uranium is an a-emitting isotope with an extremely long half-hfe, 4 billion years. As a result of this long half-life, is generally not considered to present a significant radiation hazard. However, uranium fluorides, a typical synthetic starting material, can... 

SYNS URANIUM FLUORIDE OXIDE URANYL FLUORIDE... 

In animal studies, mice injected with doses ranging from 0.05 to 1.0 jg U/testis as enriched uranium fluoride showed a general tendency for an increase in chromosome breaks with an increasing dose of enriched uranyl fluoride. At high-dose levels, the statistically significant difference of break frequencies between treated and control mice disappeared 60 days after treatment (Hu and Zhu 1990). 

Synonyms Common names Uranium 1 Uranium oxide Brown oxide Uranyl oxide Orange oxide Uranium octaoxide Yellow cake Block oxide Uranium fluoride ... 

Synonyms UN2977 uranium fluoride (fissle) Uranium (IV) chloride Uranium oxyfluoride uranium fluoride oxide bis(Acetate-B) dioxouranium bis(Nitrate-O) dioxouranium hexahydrate... 

CsFeU (s) Cesium Uranium Fluoride CsUFe (s) CsFeU (s) CsUFs (s)... 

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