Uranium (VI) fluoride

Structural formula
Crystal system	orthorhombic
Space group	Pnma (No. 62)
Lattice parameters	a = 990.0 pm b = 896.2 pm c = 520.7 pm
General
Surname	Uranium (VI) fluoride
other names	Uranium hexafluoride
Molecular formula	UF 6
Brief description	colorless crystals
External identifiers / databases
CAS number 7783-81-5 EC number 232-028-6 ECHA InfoCard 100.029.116 PubChem 24560 Wikidata Q408887
properties
Molar mass	351.99 g mol −1
Physical state	firmly
density	5.09 g cm −3 (20.7 ° C)
Sublimation point	56.5 ° C
Vapor pressure	153 hPa (25 ° C)
solubility	violent decomposition with water
Hazard and safety information
Radioactive
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary danger H and P phrases H: 330-300-373-411 P: ?
MAK	1 mg m −3
Thermodynamic properties
ΔH f 0	fixed: - (2197.7 ± 1.8)  kJ mol −1 gas: - (2148.1 ± 1.8) kJ mol −1
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Uranium (VI) fluoride (UF ₆ ), usually called uranium hexafluoride , is a chemical compound made up of the elements uranium and fluorine . It is a colorless, crystalline solid that is highly volatile , radioactive and extremely toxic. It is a very aggressive substance that attacks almost every substance and also every biological tissue . Uranium hexafluoride is stable in dry air, but reacts violently with water. In most cases it is obtained from uranium (IV) fluoride  (UF ₄ ) by reacting with elemental fluorine (F ₂ ).

At normal pressure and a temperature of 56.5 ° C, uranium hexafluoride changes directly from the solid to the gaseous state by sublimation . It is the only uranium compound that can easily be converted into the gas phase. Uranium (VI) fluoride is of particular technical importance in uranium enrichment . The uranium isotope ²³⁵ U, which is important and rare for nuclear applications, is separated from the much more common uranium isotope ²³⁸ U by means of gas diffusion processes or gas ultracentrifuges .

history

The initial synthesis of uranium hexafluoride was carried out by Otto Ruff and Alfred Heinzelmann at the Technical University of Danzig and submitted for publication on January 15, 1909. This synthesis took place in a platinum tube at −20 ° C with exclusion of moisture through the reaction of uranium (V) chloride with fluorine:

${\displaystyle {\ce {2 UCl5 + 5 F2 -> UF6 + UF4 + 5 Cl2}}}$

In the course of the completed dissertation of Alfred Heinzelmann with publication date June 27, 1911, Ruff and Heinzelmann submitted a first overview of uranium hexafluoride to the journal for inorganic chemistry on June 25, 1911 . In addition to the synthesis presented above, two further variants were presented and some properties and reactions were described.

The reaction of uranium (V) chloride with hydrogen fluoride  (HF) is not suitable for the preparation of pure UF ₆ because it is difficult to separate it from HF.

${\displaystyle {\ce {2 UCl5 + 10 HF -> UF6 + UF4 + 10 HCl}}}$

If uranium metal or uranium dicarbide  (UC ₂ ) is allowed to react with fluorine (in the presence of small amounts of chlorine as a catalyst), complete conversion to UF ₆ can be observed.

${\displaystyle {\ce {UC2 + 7 F2 -> UF6 + 2 CF4}}}$

As early as 1880, Alfred Ditte described the conversion of a green uranium oxide ( U ³ O ⁴ ) with an excess of concentrated hydrofluoric acid , which sometimes resulted in a yellow liquid that evaporated when heated and precipitated in the form of yellow transparent crystals with the formula U ² Fl ² , 4HFl . He also described an "Oxyfluorure" ( U ² OFl ² ), which is very volatile; on contact with atmospheric oxygen, the “white snow” decomposed into a black substance. These results were published again in a larger context in 1884. This information later turned out to be an error.

For a long time, uranium hexafluoride was only of interest for laboratory studies. Only with the discovery of nuclear fission in 1938 did this compound become more important, as it is the only clearly volatile and at the same time stable compound of uranium. In 1941, Aristid von Grosse summarized the properties known so far and also described the chemical behavior towards inorganic and organic substances and in glass vessels in the presence of impurities. The vapor pressure and triple point were measured by Bernard Weinstock and Ray Crist . The work was completed on February 9, 1942. The manuscript created in 1943 was released in 1947 and published in 1948. Isidor Kirshenbaum summarized the physical properties in 1943.

presentation

Uranium hexafluoride can basically be prepared from uranium metal and practically all uranium compounds by reaction with elemental fluorine and chlorine and bromine fluorides .

The educational methods can be divided into:

• Preparation from uranium (VI) compounds without changing the oxidation state , e.g. B. re-halogenation of uranium (VI) chloride  (UCl ₆ ), fluorination of uranyl fluoride  (UO ₂ F ₂ ) and the thermal decomposition of UOF ₄ , UO ₂ F ₂ or of fluorouranates (VI).
• Representation from uranium or uranium compounds with lower oxidation states, e.g. B. the oxidizing fluorination of uranium metal, uranium (V) chloride  (UCl ₅ ), the various uranium oxides , uranium carbides and uranium fluorides .
• Use of other fluorinating agents such as interhalogen compounds and noble gas fluorides.

Standard method

The common method for the preparation of uranium hexafluoride is the conversion of uranium (IV) fluoride  (UF ₄ ) with elemental fluorine  (F ₂ ). The reaction takes place at temperatures above 250 ° C and is usually carried out at 300 ° C; the reaction is endothermic :

${\displaystyle {\ce {UF4 + F2 -> UF6}}}$

If fluorine is used with a 50% excess, the reaction is complete. This process is also used technically. The fluorine is obtained from the anode process of electrolysis of a mixture of potassium fluoride and hydrogen fluoride .

In the same way, neptunium hexafluoride  (NpF ₆ ) is formed at 500 ° C from neptunium tetrafluoride  (NpF ₄ ) and F ₂ and plutonium hexafluoride  (PuF ₆ ) at 750 ° C from plutonium tetrafluoride  (PuF ₄ ) and F ₂ .

With other fluorine compounds

All uranium oxides react with chlorine trifluoride  (ClF ₃ ), bromine trifluoride  (BrF ₃ ) and bromine pentafluoride  (BrF ₅ ) to form UF ₆ . The reactivity of the halogen fluoride is higher than that of elemental fluorine. UO ₂ reacts with BrF ₃ at around 50 ° C, whereas the reaction with fluorine only takes place at around 400 ° C. The halogen fluorides react violently with uranium metal; reaction with BrF ₃ vapor can lead to explosion.

Even with noble gas fluorides such. B. Xenon difluoride  (XeF ₂ ) UF _{4 is} converted to UF ₆ at a higher temperature under pressure or in liquid HF .

Nitrogen trifluoride  (NF ₃ ) fluorinates uranium metal, UO ₂ , UF ₄ , UO ₃ , U ₃ O ₈ and UO ₂ F ₂  · 2 H ₂ O at temperatures between 100 and 550 ° C to form UF ₆ . NF ₃ is therefore seen as a potential replacement for previous fluorinating agents in the existing nuclear fuel cycle and in the reprocessing of volatile actinide compounds.

properties

Physical Properties

Uranium hexafluoride forms colorless crystals that sublime under normal pressure  (1,013.25  hPa ) at 56.54 ° C, i.e. change directly from the solid to the gaseous state.

Uranium hexafluoride crystals in a glass ampoule

It can be stored indefinitely at room temperature in quartz or Pyrex vials, provided that it is ensured that there are no traces of moisture, that the glass itself is free of all gas inclusions and that any hydrogen fluoride  (HF) present has been completely removed.

Phase diagram of UF ₆

Parameters for the Antoine equation lg P = A − B / (T + C); at 64-116 ° C
A.	B.	C.
6.99464	1126.288	221.963
lg P = A − B / (T + C); at> 116 ° C
A.	B.	C.
7,69069	1683.165	302.148

The triple point at which the three phases solid, liquid and gaseous are in equilibrium is at a temperature of 64.05 ° C and a pressure of 1133 ± 7 mmHg (approx. 1510  hPa ). A liquid phase is only possible above this pressure.

The critical point from which liquid and gas can no longer be distinguished from one another is at a temperature ( T _c ) of 230.2 ° C, a pressure ( p _c ) of 45.5  atm  (46.1 bar), a molar volume  ( V _{m, c} ) of 256.0  cm ³ · mol ^-1 and a density (ρ _C ) of 1.375 g · cm ^-3 . The vapor pressure at 25 ° C is 153 mbar (153 hPa).

The volatility of UF ₆ is similar to that of neptunium hexafluoride  (NpF ₆ ) and plutonium hexafluoride  (PuF ₆ ); together they belong to the three previously known hexafluorides of the actinide elements .

The Bildungsentropie  (S ⁰ _m ) is fixed for UF ₆ : -430.4 ± 1.5  J · K ^-1 · mol ^-1 , gaseous UF ₆ : -280.4 ± 1.5 J · ^{K -1} · mol ⁻¹ . The sublimation enthalpy  (ΔH _s ) at the sublimation point (56.54 ° C) is 48.23 kJ · mol ⁻¹ ; the enthalpy of vaporization  (ΔH _v ) at the triple point (64.05 ° C) is 28.76 kJ mol ⁻¹ .

Uranium hexafluoride is paramagnetic ; the molar magnetic susceptibility χ _mol is 43 · 10 ⁻⁶  cm ³ · mol ⁻¹ .

Crystal and molecular structure

Uranium hexafluoride is a covalent compound and not a salt. The UF ₆ molecule is octahedral  ( O _h ); in the gaseous state the U – F bond length is 199.6 pm.

• 

  Bond length and angle in gaseous uranium hexafluoride

• 

  Unit cell of uranium hexafluoride

Uranium hexafluoride crystallizes in the orthorhombic crystal system at 293 K (20 ° C) in the space group  Pnma (No. 62) with the lattice parameters a  = 990.0  pm , b  = 896.2 pm and c  = 520.7 pm with four formula units per unit cell . In the crystal, the molecules show a slight deviation from the regular octahedral coordination. At 293 K (20 ° C) the measured deviations from the librational movements of the fluorine atoms are +1.5 pm for the U – F and +2.0 pm for the F – F distances. The corrected distances for U – F are 199.2–200.4 pm, for F – F 280.4–282.6 pm and the F – U – F angle 89.42 (17) –90.20 (11 ) °.

When cooling to 193 K (−80 ° C), the lattice parameters decrease to a  = 984.3 pm, b  = 892.0 pm and c  = 517.3 pm. The hexagonal packing tends to be more regular, the F – F distances outside a UF ₆ octahedron are shortened. The octahedra of the molecules are almost regular with a mean U – F distance of 198 pm, a mean F – F edge length of 280 pm, and an F – U – F angle of 90.0 ° at 193 K.

Upon further cooling to 77 K (−196 ° C) the metal-fluorine bond lengths do not decrease significantly, but the atomic coordinates continue to approximate the ideal coordinates of the hexagonal packing of the fluorine atoms.

Spectroscopic properties

Uranium hexafluoride has six fundamental vibrations . ν ₁ and ν ₂ are stretching vibrations , ν ₅ and ν ₆ are bending vibrations . The normal coordinate of ν ₃ consists mainly of a stretching, that of ν ₄ mainly of a bend. Of these, ν ₁ , ν ₂ and ν _{5 are} Raman-active , ν ₃ and ν _{4 are} IR-active , ν ₆ is IR- and Raman-inactive.

Fundamental vibration	ν 1	ν 2	ν 3	ν 4	ν 5	ν 6
Term symbol	A 1g	E g	F 1u	F 1u	F 2g	F 2u
Wave number  (cm −1 )	667 ± 1	534 ± 1	626 ± 1	186 ± 1	200 ± 1	143 ± 2
IR active	-	-	+	+	-	-
Raman active	+	+	-	-	+	-

Chemical properties

Uranium hexafluoride is stable in dry air. On the other hand, it reacts very violently with water (due to humidity in the air), producing the water-soluble uranyl fluoride  (UO ₂ F ₂ ) and hydrogen fluoride  (HF). HF forms highly corrosive hydrofluoric acid in excess water .

${\displaystyle {\ce {UF6 + 2 H2O -> UO2F2 + 4 HF}}}$

UF ₆ is a powerful fluorinating and oxidizing agent . It reacts with most metals and alloys (e.g. iron, aluminum-magnesium alloys, stainless steels) with the formation of metal fluorides, very slowly at room temperature and somewhat faster at elevated temperatures. Since the fluorides formed are of low volatility, they form deposits on the surfaces in question, which can prevent further reaction. Nickel in particular is very chemically resistant. Synthetic high polymers, such as. B. Teflon and some copolymers also show good resistance to UF ₆ . Organic compounds , on the other hand, already react at room temperature by fluorination with UF ₆ ; in the process, HF and UF _{4 are formed} with the deposition of carbon . Oxygen-containing organic compounds such as. B. Ethanol or diethyl ether react quickly with the deposition of uranyl fluoride and formation of HF.

use

Cascade of gas centrifuges for uranium enrichment

→ Main article : Uranium enrichment

Uranium hexafluoride is used to separate the uranium isotopes using the gas diffusion process or by means of gas ultracentrifuges . It is ideally suited for this because, unlike most other uranium compounds, it can easily be converted into the gas phase and because fluorine is a pure element : There is only one isotope of fluorine ( ¹⁹ F) in nature; all natural fluorine atoms have exactly the same atomic mass . Therefore the mass differences of the uranium hexafluoride molecules, which are used in the isotope separation - as desired - can only be traced back to the mass differences of the uranium isotopes ²³⁸ U and ²³⁵ U. Uranium hexafluoride is therefore part of the nuclear fuel cycle . For further use in pressurized and boiling water reactors , enriched uranium hexafluoride is transported to fuel element factories, where it is first processed into uranium dioxide and finally into fuel elements .

For the reprocessing of spent fuel elements, it was suggested to separate the uranium (95% of the total mass) that the material should be finely shredded and treated with elemental fluorine (“direct fluorination”). The resulting volatile fluorides (mainly UF ₆ and small amounts of NpF ₆ ) can easily be removed from the non-volatile fluorides, e.g. B.  Separate plutonium (IV) fluoride (PuF ₄ ), americium (III) fluoride  (AmF ₃ ), curium (III) fluoride  (CmF ₃ ) and the fluorides of most of the cleavage products . Neptunium hexafluoride (NpF ₆ ) and plutonium hexafluoride (PuF ₆ ) are sensitive to UV light and decompose to form tetrafluorides and fluorine. They can therefore be removed photochemically from a mixture with UF ₆ .

Transport and Storage

UF ₆ tank

Since the production, isotope separation and processing sites are located in different locations, the transport and storage of uranium hexafluoride is necessary. It is transported by road, rail or ship. Special tanks are available for this, which must comply with the ANSI N14.1 or ISO 7195 standards. Steel tanks of the types 48 F or 48 Y are mainly used . They have a diameter of 48  inches  (approx. 122 cm), a wall thickness of 16 mm and can hold up to 12.5 tons. Smaller type 30 B containers are used to transport the enriched uranium hexafluoride . They are 30 inches in diameter with a capacity of 2.277 tons. The Hazardous Goods Ordinance on Road, Rail and Inland Shipping (GGVSEB) contains a regulation for the approval of the type of packaging for non-fissile or fissile exempt uranium hexafluoride .

The transports are regulated by the IAEA . However, they are controversial and led, among other things, to several inquiries in the German Bundestag and the state parliament of Baden-Württemberg . These transports are in the public discussion particularly after a fire broke out on the uranium hexafluoride cargo ship Atlantic Cartier in the port of Hamburg on May 1, 2013 and there were considerable difficulties in extinguishing it.

Uranium hexafluoride storage yard in Paducah (USA)

In the United States, at least 46,422 drums of uranium hexafluoride were stored in at least three locations in 2000: 4,683 drums were stored on the premises of the former uranium enrichment facility called K-25 near Oak Ridge , Tennessee, 28,351 in the uranium enrichment facility in Paducah , Kentucky, and 13,388 in the Uranium enrichment facility in Portsmouth , Ohio.

Leak in a uranium hexafluoride cylinder

There have been several uranium hexafluoride accidents in the United States. One occurred in 1986 at a Sequoyah Fuels Corporation facility near Gore , Oklahoma . When an overfilled tank was heated to remove spilled material, the tank burst open.

Physiological effects and safety information

Uranium hexafluoride acts on the human body mainly in three different ways:

• It is a very aggressive substance that attacks any tissue. When the gas comes into contact with body fluids, hydrofluoric acid is formed , which causes chemical burns on the skin and the mucous membranes of the respiratory tract . Human exposure to the gas initially affects the eyes and respiratory tract, causing irritation, loss of vision, coughing, and excessive saliva and sputum formation. After prolonged exposure, this leads to pneumonitis and pulmonary edema and can lead to death.
• Like all hexavalent uranium compounds, it is very toxic when inhaled and swallowed. In addition, there is a risk of accumulation in the human body, especially in the liver and kidneys.
• Like all uranium compounds, it is radioactive . The activity depends on the isotopic composition of the uranium. ²³⁸ U has a half-life of 4.468 billion years and, like the other natural isotopes ( ²³⁴ U and ²³⁵ U), is an α-emitter . The specific activity of ²³⁸ U is 12.35  Bq / mg . ²³⁵ U has a half-life of 704 million years. It is fissile and has a share of around 0.7% in natural uranium deposits. Enriched uranium hexafluoride is significantly more active due to its lower half-life.

For the workers in the Paducah plant, there are mortality studies available as part of a retrospective study on health problems and suicide risks .

literature

• Alfred Heinzelmann: The uranium hexafluoride, a contribution to the knowledge of hexavalent uranium (dissertation, Danzig, June 27, 1911), 55 p. ( Digitized version ). - Note in: Directory of the publications published at the technical universities of the German Reich up to the end of 1912 , p. 60 ( limited preview in the Google book search).
• Gmelin's Handbook of Inorganic Chemistry , System No. 55, Uranium, Part A, pp. 121-123.
• Gmelin's Handbook of Inorganic Chemistry , System No. 55, Uranium, Part C 8, pp. 71-163.
• R. DeWitt: Uranium hexafluoride: A survey of the physico-chemical properties , Technical report, GAT-280; Goodyear Atomic Corp., Portsmouth, Ohio; August 12, 1960, 164 pp. ( Doi: 10.2172 / 4025868 ).
• Ingmar Grenthe, Janusz Drożdżynński, Takeo Fujino, Edgar C. Buck, Thomas E. Albrecht-Schmitt, Stephen F. Wolf: Uranium ; in: Lester R. Morss, Norman M. Edelstein, Jean Fuger (Eds.): The Chemistry of the Actinide and Transactinide Elements , Springer, Dordrecht 2006; ISBN 1-4020-3555-1 , pp. 253-698 ( doi: 10.1007 / 1-4020-3598-5_5 ), here pp. 530-531, 557-564.

Individual evidence

1. ↑ ^{a b c d e f g} Entry on uranium hexafluoride in the GESTIS substance database of the IFA , accessed on February 10, 2020(JavaScript required) .
2. ↑ Gmelin's Handbook of Inorganic Chemistry , System No. 55, Uranium, Part C 8, p. 90.
3. ↑ Not explicitly listed in Regulation (EC) No. 1272/2008 (CLP) , but with the specified labeling it falls under the group entry uranium compounds with the exception of those specified elsewhere in this Annex in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA) , accessed on February 10, 2020. Manufacturers or distributors can expand the harmonized classification and labeling .
4. ↑ The hazards emanating from radioactivity do not belong to the properties to be classified according to the GHS labeling.
5. ↑ ^{a b c} Gerald K. Johnson: The Enthalpy of Formation of Uranium Hexafluoride ; in: The Journal of Chemical Thermodynamics , 1979, 11  (5), pp. 483-490 ( doi: 10.1016 / 0021-9614 (79) 90126-5 ).
6. ↑ Otto Ruff: About some new fluorides ; in: Chem. Ber. , 1909, 42  (1), pp. 492-497, here pp. 495-497 ( doi: 10.1002 / cber.19090420175 ).
7. ↑ Alfred Heinzelmann: Das Uranhexafluorid, a contribution to the knowledge of hexavalent uranium (dissertation, Danzig, June 27, 1911), 55 pp. ( Digitized version ).
8. ↑ ^{a b c} Otto Ruff, Alfred Heinzelmann: About the uranium hexafluoride ; in: Zeitschrift für inorganic Chemie , 1911, 72  (1), pp. 63-84 ( doi: 10.1002 / zaac.19110720106 ).
9. ↑ ^{a b c} Original spelling (!).
10. ↑ A. Ditte: Sur les composés fluorés de l'uranium ; in: Compt. Rend. , 1880, 91 , pp. 115-118 ( digitized on Gallica ).
11. ^ Alfred Ditte: Recherches sur l'uranium ; in: Ann. Chim. Phys. , 1884, 6  (1), pp. 338-358 ( digitized on Gallica ).
12. ↑ Arthur Smithells: On some fluorine compounds of uranium ; in: J. Chem. Soc., Trans. , 1883, 43 , pp. 125-135 ( doi: 10.1039 / CT8834300125 ).
13. ↑ Gmelin's Handbook of Inorganic Chemistry , System No. 55, Uran, Part A, pp. 121–123.
14. ↑ Gmelin's Handbook of Inorganic Chemistry , System No. 55, Uranium, Part C 8, p. 71.
15. ↑ Aristid v. Large: Chemical Properties of Uranium Hexafluoride, UF ₆ ; Technical Report, A-83; Columbia University, New York, NY; June 25, 1941 ( doi: 10.2172 / 962915 ).
16. ↑ ^{a b c} B. Weinstock, RH Crist: The Vapor Pressure of Uranium Hexafluoride ; in: J. Chem. Phys. , 1948, 16 , pp. 436-441 ( doi: 10.1063 / 1.1746915 ; Maschinoscript (April 12, 1943) ).
17. ↑ ^{a b} I. Kirshenbaum: The Physical Properties of Uranium Hexafluoride ; Technical Report, 2M-503; 2R-464; A-753; SAM Labs; July 1, 1943 ( doi: 10.2172 / 4416966 ).
18. ↑ Gmelin's Handbook of Inorganic Chemistry , System No. 55, Uran, Part C 8, pp. 72-85.
19. ↑ US Patent 2535572: Preparation of UF ₆ , December 26, 1950 ( PDF ).
20. ↑ Gmelin's Handbook of Inorganic Chemistry , System No. 55, Uranium, Part C 8, p. 80.
21. ^ ^{A b c} John G. Malm, Bernard Weinstock, E. Eugene Weaver: The Preparation and Properties of NpF ₆ ; a comparison with PuF ₆ ; in: J. Phys. Chem. , 1958, 62  (12), pp. 1506-1508 ( doi: 10.1021 / j150570a009 ).
22. ↑ ^{a b} Gmelin's Handbook of Inorganic Chemistry , System No. 55, Uranium, Part C 8, pp. 78–80.
23. ↑ Gmelin's Handbook of Inorganic Chemistry , System No. 55, Uranium, Part C 8, p. 76.
24. ↑ Bruce McNamara, Randall Scheelea, Anne Kozeliskya, Matthew Edwards: Thermal Reactions of Uranium Metal, UO ₂ , U ₃ O ₈ , UF ₄ , and UO ₂ F ₂ with NF ₃ to produce UF ₆ ; in: Journal of Nuclear Materials , 2009, 394  (2-3), pp. 166-173 ( doi: 10.1016 / j.jnucmat.2009.09.004 ).
25. ↑ ^{a b c} George D. Oliver, HT Milton, JW Grisard: The Vapor Pressure and Critical Constants of Uranium Hexafluoride ; in: J. Am. Chem. Soc. , 1953, 75  (12), pp. 2827-2829 ( doi: 10.1021 / ja01108a011 ).
26. ↑ Ferdinand G. Brickwedde, Harold J. Hoge, Russell B. Scott: The Low Temperature Heat Capacities, Enthalpies, and Entropies of UF ₄ and UF ₆ ; in: J. Chem. Phys. , 1948, 16 , pp. 429-436 ( doi: 10.1063 / 1.1746914 ).
27. ↑ Gmelin's Handbook of Inorganic Chemistry , System No. 55, Uranium, Part C 8, p. 95.
28. ↑ Gmelin's Handbook of Inorganic Chemistry , System No. 55, Uranium, Part C 8, p. 97.
29. ↑ Joseph F. Masi: The Heats of Vaporization of Uranium Hexafluoride ; in: J. Chem. Phys. , 1949, 17 , pp. 755-758 ( doi: 10.1063 / 1.1747395 ).
30. ↑ Gmelin's Handbook of Inorganic Chemistry , System No. 55, Uran, Part C 8, pp. 100-101.
31. ^ Paul Henkel, Wilhelm Klemm : Magnetochemical Investigations. XII. The Magnetic Behavior of Some Volatile Fluorides ; in: Zeitschrift für inorganic Chemie , 1935, 222 , pp. 70-72 ( doi: 10.1002 / zaac.19352220110 ).
32. ^ Woldemar Tilk, Wilhelm Klemm: Magnetochemical investigations. XXXI. About the paramagnetism of compounds of hexavalent chromium, molybdenum, tungsten and uranium ; in: Zeitschrift für inorganic Chemie , 1939, 240 , pp. 355-368 ( doi: 10.1002 / zaac.19392400408 ).
33. ↑ Gmelin's Handbook of Inorganic Chemistry , System No. 55, Uranium, Part C 8, p. 119.
34. ↑ ^{a b} Masao Kimura, Werner Schomaker, Darwin W. Smith, Bernard Weinstock: Electron-Diffraction Investigation of the Hexafluorides of Tungsten, Osmium, Iridium, Uranium, Neptunium, and Plutonium ; in: J. Chem. Phys. , 1968, 48  (8), pp. 4001-4012 ( doi: 10.1063 / 1.1669727 ).
35. ^ ^{A b} J. C. Taylor, PW Wilson, JW Kelly: The Structures of Fluorides. I. Deviations from Ideal Symmetry in the Structure of Crystalline UF ₆ : A Neutron Diffraction Analysis ; in: Acta Cryst. , 1973, B29 , pp. 7-12 ( doi: 10.1107 / S0567740873001895 ).
36. ^ ^{A b c} John H. Levy, John C. Taylor, Paul W. Wilson: Structure of Fluorides. Part XII. Single-crystal Neutron Diffraction Study of Uranium Hexafluoride at 293 K ; in: J. Chem. Soc., Dalton Trans. , 1976, pp. 219-224 ( doi: 10.1039 / DT9760000219 ).
37. ^ ^{A b} J.C. Taylor, PW Wilson: The Structures of Fluorides X. Neutron Powder Diffraction Profile Studies of UF ₆ at 193 ° K and 293 ° K ; in: Journal of Solid State Chemistry , 1975, 14  (4), pp. 378-382 ( doi: 10.1016 / 0022-4596 (75) 90059-6 ).
38. ^ JH Levy, JC Taylor, AB Waugh: Neutron Powder Structural Studies of UF ₆ , MoF ₆ and WF ₆ at 77 K ; in: Journal of Fluorine Chemistry , 1983, 23  (1), pp. 29-36 ( doi: 10.1016 / S0022-1139 (00) 81276-2 ).
39. Jump up ↑ Howard H. Claassen, Gordon L. Goodman, John H. Holloway, Henry Selig: Raman Spectra of MoF ₆ , TcF ₆ , ReF ₆ , UF ₆ , SF ₆ , SeF ₆ , and TeF ₆ in the Vapor State ; in: J. Chem. Phys. , 1970, 53  (1), pp. 341-348 ( doi: 10.1063 / 1.1673786 ).
40. ↑ B. Weinstock, EE Weaver, JG Malm: Vapor Pressures of NpF ₆ and PuF ₆ ; Thermodynamic Calculations with UF ₆ , NpF ₆ and PuF ₆ ; in: Journal of Inorganic and Nuclear Chemistry , 1959, 11  (2), pp. 104-114 ( doi: 10.1016 / 0022-1902 (59) 80054-3 ).
41. ^ Ezra Bar-Ziv, Mira Freiberg, Shmuel Weiss: The Infrared Spectrum of UF ₆ ; in: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy , 1972, 28  (11), pp. 2025-2028 ( doi: 10.1016 / 0584-8539 (72) 80176-4 ).
42. ↑ Robin S. McDowell, Larned B. Asprey, Robert T. Paine: Vibrational Spectrum and Force Field of Uranium Hexafluoride ; in: J. Chem. Phys. , 1974, 61  (9), pp. 3571-3580 ( doi: 10.1063 / 1.1682537 ).
43. ↑ ER Bernstein, GR Meredith: Vibrational Spectra of Transition Metal Hexafluoride Crystals: III. Exciton Band Structures of MoF ₆ , WF ₆ and UF ₆ ; in: Chemical Physics , 1977, 24  (3), pp. 311-325 ( doi: 10.1016 / 0301-0104 (77) 85091-X ).
44. ^ KC Kim, RN Mulford: Vibrational Properties of Actinide (U, Np, Pu, Am) Hexafluoride Molecules ; in: Journal of Molecular Structure: THEOCHEM , 1990, 207  (3-4), pp. 293-299 ( doi: 10.1016 / 0166-1280 (90) 85031-H ).
45. ↑ Gmelin's Handbook of Inorganic Chemistry , System No. 55, Uranium, Part C 8, p. 126.
46. ↑ RW Kessie: Plutonium and Uranium Hexafluoride Hydrolysis Kinetics ; in: Ind. Eng. Chem. Proc. Of. Dev. , 1967, 6  (1), pp. 105-111 ( doi: 10.1021 / i260021a018 ).
47. ↑ ^{a b} Gmelin's Handbook of Inorganic Chemistry , System No. 55, Uranium, Part C 8, pp. 146–148.
48. ↑ Gmelin's Handbook of Inorganic Chemistry , System No. 55, Uranium, Part C 8, p. 160.
49. ↑ Jan Uhlíř, Martin Marečeka: Fluoride Volatility Method for Reprocessing of LWR and FR Fuels ; in: Journal of Fluorine Chemistry , 2009, 130  (1), pp. 89-93 ( doi: 10.1016 / j.jfluchem.2008.07.002 ).
50. ↑ James V. Beitz, Clayton W. Williams: Photochemical Removal of NpF ₆ and PuF ₆ from UF ₆ Gas Streams , international symposium to commemorate the 50th anniversary of discovery of transuranium elements, Washington, DC (USA), 26.-31. August 1990 ( abstract ; PDF ); accessed on February 10, 2020.
51. ↑ US Patent 5723837: Uranium Hexafluoride Purification , March 3, 1998 ( PDF ).
52. ↑ Business Association for the Nuclear Fuel Cycle and Nuclear Technology e. V .: Uranium hexafluoride transports ( Memento from July 14, 2014 in the Internet Archive ).
53. ↑ Ben G. Dekker: Transport of UF ₆ in Compliance with TS-R-1. (PDF) 2004, accessed on February 10, 2020 (English). 
54. ↑ ^{a b} DUF ₆ Guide: UF ₆ Cylinder Data Summary (US Department of Energy); accessed on February 10, 2020.
55. ↑ Julia Beißwenger: Interim storage facility through uranium enrichment , dradio.de, Deutschlandfunk, Forschung Aktuell , July 28, 2011; accessed on February 10, 2020.
56. ↑ Federal Office for Radiation Protection : Permits according to § 3 Paragraph 1. StrlSchV or § 6 AtG for the interim storage of depleted or natural and enriched uranium in the form of uranium hexafluoride (UF ₆ ) ; Approval requirements and requirements ; accessed on February 10, 2020.
57. ↑ Federal Ministry of Justice: Ordinance on the domestic and cross-border transport of dangerous goods by road, rail and inland waterways (Hazardous Goods Ordinance on Road, Rail and Inland Shipping - GGVSEB); § 8 Responsibilities of the Federal Institute for Materials Research and Testing; Sentence 2 (as of January 22, 2013); accessed on February 10, 2020.
58. ↑ IAEA-TECDOC-608: Interim guidance on the safe transport of uranium hexafluoride ; July 1991 (PDF; 2.7 MB); accessed on February 10, 2020.
59. ^ Gerhard Piper: International uranium hexafluoride tourism through Germany ; Telepolis, June 30, 2007; accessed on February 10, 2020.
60. ↑ German Bundestag Printed Matter 14/435: transport of uranium hexafluoride ; March 23, 1999 (PDF; 213 kB); accessed on February 10, 2020.
61. ↑ German Bundestag Printed Matter 14/6692: transportation and storage of uranium hexafluoride in the Federal Republic of Germany ; July 16, 2001 (PDF; 375 kB); accessed on February 10, 2020.
62. ↑ German Bundestag Printed Matter 16/5174: transportation and storage of uranium hexafluoride ; April 27, 2007 (PDF; 114 kB); accessed on February 10, 2020.
63. ↑ German Bundestag, printed matter 17/253: Uranium hexafluoride - Safe storage and proper handling to avoid environmental risks ; December 16, 2009 (PDF; 2.3 MB); accessed on February 10, 2020.
64. ↑ German Bundestag Printed Matter 18/1726: transportation and storage of uranium hexafluoride and uranium oxide related to uranium enrichment in Gronau ; June 11, 2014 (PDF); accessed on February 10, 2020.
65. ↑ State Parliament of Baden-Württemberg, printed matter 14/4880: Security of uranium hexafluoride transports through Baden-Württemberg ; July 21, 2009 (PDF; 39 kB); accessed on February 10, 2020.
66. ^ Zeit online: Burning freighter loaded radioactive material , May 17, 2013; accessed on February 10, 2020.
67. ^ Mary Byrd Davis: What's Ahead for the Nation's Depleted Uranium Hexafluoride? ( Memento of March 10, 2013 in the Internet Archive ), November 5, 2000; Yggdrasil Institute (a project of the Earth Island Institute); accessed on February 10, 2020.
68. Jump up ↑ Assessment of the Public Health Impact From the Accidental Release of UF ₆ at the Sequoyah Fuels Corporation Facility at Gore, Oklahoma (PDF; 3.1 MB); Docket No. 40-8027. License No. SUB-1010. Manuscript Completed: March 1986; Date Published: March 1986. Ad Hoc Interagency Public Health Assessment Task Force, US Nuclear Regulatory Commission; Washington, DC 20555.
69. ↑ Stephen A. McGuire: Chemical Toxicity of Uranium Hexafluoride Compared to Acute Effects of Radiation , NUREG-1391, US Nuclear Regulatory Commission, 1991 ( PDF ); accessed on February 10, 2020.
70. ^ ^{A b} G. Audi, O. Bersillon, J. Blachot, AH Wapstra: The NUBASE evaluation of nuclear and decay properties. In: Nuclear Physics. Volume A 729, 2003, pp. 3-128. doi : 10.1016 / j.nuclphysa.2003.11.001 . ( PDF ; 1.0 MB).
71. ↑ Federal Institute for Risk Assessment : BfR recommends deriving a European maximum value for uranium in drinking and mineral water , Joint Statement No. 20/2007 of the BfS and the BfR of April 5, 2007, p. 7 (Table 1: Specific activities of U 234 , U 235 and U 238 based on 1 mg of natural uranium); accessed on February 10, 2020.
72. ↑ C. Chan, TS Hughes, S. Muldoon, T. Aldrich, C. Rice, R. Hornung, G. Brion, DJ Tollerud: Mortality patterns among Paducah Gaseous Diffusion Plant workers ; in: J Occup Environ Med , 2010, 52  (7), pp. 725-732 ( PMID 20595915 ; PMC 2983475 (free full text)).
73. ↑ LW Figgs, H. Holsinger, SJ Freitas, GM Brion, RW Hornung, CH Rice, D. Tollerud: Increased suicide risk among workers following toxic metal exposure at the Paducah gaseous diffusion plant from 1952 to 2003: a cohort study ; in: Int J Occup Environ Med , 2011, 2  (4), pp. 199-214 ( PMID 23022839 ).

Web links

Commons : Uranium Hexafluoride  - Collection of Pictures, Videos and Audio Files

• Simon Cotton (Uppingham School, Rutland, UK): Uranium Hexafluoride ; accessed on February 10, 2020.
• DUF ₆ Guide: Uranium Hexafluoride (UF ₆ ) - Physical and chemical properties of UF ₆ , and its use in uranium processing - Uranium Hexafluoride and Its Properties (US Department of Energy); accessed on February 10, 2020.

This article was added to the list of articles worth reading on November 9, 2011 in this version .