Uranyl fluoride

Are caustic materials processed If these are released and contact people either as a vapor or liquid severe health hazards result. For example, uranyl fluoride forms hydrofluoric acid in the lungs. 

Figure 3. Distribution of uranyl complexes as a function of pH at 25°C in presence of typical ligands in surface and ground waters (PCO2 = 10 atm, E F = 0.3 ppm, E Cl = 10 ppm, E SO4 = 100 ppm, E PO4 = 0.1 ppm, E Si02 = 30 ppm). Below pH 4-5 uranyl (U02 ) ion and uranyl fluoride complexes predominate, at intermediaiy pHs (4.5 < pH < 7.5) U02(HP04)2 is the predominant species, whereas at higher pH uranyl is complexed with carbonates. [Used with permission of Elsevier Science, from Langmuir (1978) Geochim Cosmochim Acta, Vol. 42, Fig. 11, p. 558].

Excer A process for making uranium tetrafluoride by electrolytic reduction of a uranyl fluoride solution, precipitation of a uranium tetrafluoride hydrate, and ignition of this. 

The three-dimensional structure of insulin remained recalcitrant in spite of the knowledge of its primary sequence. The early crystals had been found by Scott (1936) to contain zinc which could be replaced by other divalent metals. The zinc atom is not heavy enough to be unambiguously distinguishable. Eventually it proved possible to introduce uranyl acetate and uranyl fluoride into the insulin molecule and to obtain the three-dimensional structure, first at 2.8 A resolution and then at 1.9 A (see Blundell, Dodson, Hodgkin, and Mercola, 1972). 

Ferris, L.M. Ammonium fluoride-uranyl fluoride-water system, J. Chem. Eng. Data, 5(3) 241,1960. 

Ferris, L.M. Solubility of uranyl fluoride in hydrofluoric acid-nitric acid solutions at 25°, J. Am. Chem. Soc., 87(23) 5377-5379, 1965. 

Synonyms Soluble Uranyl nitrate, uranyl fluoride, uranium hexafluoride insoluble uranium dioxide, uranium tetrafluoride... 

Enriched UF6 is processed into U02 powder at fuel fabrication facilities using one of several methods. In one process uranium hexafluoride is vaporized and then absorbed by water to produce uranyl fluoride, U02F2, solution. Ammonium hydroxide is added to this solution and ammonium diuranate is precipitated. Ammonium diuranate is dried, reduced, and milled to make uranium dioxide powder. The powder is pressed into fuel pellets for nuclear reactors. 

Ammonium hydroxide is added to the uranyl fluoride solution to quantitatively precipitate ammonium diuranate... 

The dioxide difluorides of U, Np, Pu, and Am have all been isolated. Uranyl fluoride, being an important intermediate in the conversion of enriched UF6 to UO2 for the production of fuel rods for Advanced Gas-Cooled Nuclear Reactors, is undoubtedly the most studied. The majority of papers on UO2F2, therefore, are concerned with its formation from the reaction of UF6 with steam or its conversion to UO2 by reduction with hydrogen. 

In the laboratory, anhydrous uranyl fluoride may be prepared by a variety of methods, the most favored being by the reaction of uranium... 

Uranyl fluoride is a pale-yellow solid, which, on exposure to moist air, readily forms the dihydrate. It is stable in air up to 400°C and up to 700°C in a closed system. Above 760°C it dissociates to give U3O8, UF6, and O2 (244, 245). It is very soluble in water and UF6 and is usually present in the latter. 

Other actinide(VI) oxide fluorides exist. The thermal decomposition of UOF4 at 290°C (226) and the reaction of uranyl fluoride with SeF4 (275) yield a yellow solid, which is U203F6. The compound U205F2 is formed as the dihydrate in the U03-HF-H20 system (276) and when UF6 reacts with a small quantity of water, U305F8 is the product (275). 

Diamond, G.L., Morrow, P.E., Parmer, B.J., Gelein, R.M., Baggs, R.B. (1989). Reversible uranyl fluoride nephrotoxicity in the Long Evans rat. Fundam. Appl. Toxicol. 13 65-78. 

SYNS URANIUM FLUORIDE OXIDE URANYL FLUORIDE... 

URANYL CHLORIDE see URAOOO URANYL FLUORIDE see UQAOOO URANYL NITRATE (soHd) see URA200 URANYL NITRATE HEXAHYDRATE see URSOOO URANYL NITRATE HEXAHYDRATE, solution (DOT) see URSOOO... 

Uranium hexafluoride is hydrolyzed to uranyl fluoride and hydrogen fluoride. Hydrogen fluoride is highly toxic in acute exposures and causes pulmonary edema, which may be immediately life-threatening. 

Deaths occurred after accidental releases of uranium hexafluoride at uranium-processing facilities in 1944 and 1986, but these deaths were not attributed to the uranium component of this compound (Kathren and Moore 1986 Moore and Kathren 1985 USNRC 1986). These releases resulted in the generation of concentrated aerosols of highly toxic hydrofluoric acid and uranyl fluoride. In the 1944 incident exposure time was estimated to be only 17 seconds, deaths occurred in 2 of 20 workers within an hour and were attributed to severe chemical burns of the lungs. In the 1986 incident, 1 of 23 workers died from massive pulmonary edema, indicating that inhalation of hydrofluoric acid was responsible for death. Estimated airborne concentrations were 20 mg uranium hexafluoride/m for a 1-minute exposure and 120 mg uranium hexafluoride/m for a 60-minute exposure (15.2 and 91 mg U/m, respectively). 

Uranium hexafluoride rapidly dissociates into hydrofluoric acid and uranyl fluoride on contact with moisture in the air. 

An exposure to 9.5 mg U/m (as uranyl nitrate hexahydrate) for 8 hours per day, 5 days per week for 30 days caused 10% mortality in rats and guinea pigs, and 75% mortality in dogs. Exposure to 2 mg U/m killed all four cats tested (Roberts 1949). Exposure to 9.2 mg U/m (as uranyl fluoride)... 

The pulmonary toxicity of uranium compounds varies in animals. Reports of pulmonary toxicity in animals after acute-duration exposure to uranium are limited to experiments with uranium hexafluoride. Gasping and severe irritation to the nasal passages were reported after 10 minute exposures at 637 mg U/mg in rats and mice (Spiegl 1949) and nasal hemorrhage in rats after a 5 minute exposure to 54,503 mg/m (Leach et al. 1984). Uranium hexafluoride promptly hydrolyzes on contact with water to uranyl fluoride and hydrofluoric acid. Thus, the animals were potentially exposed to hydrofluoric acid, a potent toxicant to respiratory tract epithelium, which probably contributed to pulmonary tissue destruction (Leach et al. 1984 Spiegl 1949 Stokinger et al. 1953). In addition, exposure to fluoride ions can result in hypocalcemia, hypomagnesemia, pulmonary edema, metabolic acidosis, ventricular arrhythmia, and death (Meditext 1998). 

Renal effects can be produced in animals after acute-duration inhalation exposures to uranium. A 10-minute exposure to 637 mg U/m as uranium hexafluoride produced severe degeneration of the cortical tubules 5-8 days later in rats (Spiegl, 1949). These same effects were observed in dogs 1-3 days after a 1-hour exposure to 250 mg U/m as uranyl fluoride (Morrow et al. 1982). Proteinuria and glucosuria were also observed in rats after 2-10-minute exposures to uranium hexafluoride (Leach et al. 1984). 

No effects on body weight were observed after several intermediate-duration dosing studies that lasted 4—5 weeks. These studies researched exposures by the inhalation route as follows 16 mg U/m as uranium trioxide to rats, rabbits, dogs, and cats 19 mg U/m as uranium dioxide to mice 16 mg U/m as uranium dioxide to guinea pigs 9.2 mg U/m as uranyl fluoride to dogs and rabbits 2.2 mg U/m as uranyl fluoride to rats 9.2 mg U/m as uranium dioxide to dogs 19.2 mg U/m as uranium dioxide to rabbits ... 

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