Fluorine has only a single naturally occurring stable isotope, so isotopologues of Template:Chem2 differ in their molecular weight based solely on the uranium isotope present.[11] This difference is the basis for the physical separation of isotopes in enrichment.
All the other uranium fluorides are nonvolatile solids that are coordination polymers.
Gaseous diffusion requires about 60 times as much energy as the gas centrifuge process: gaseous diffusion-produced nuclear fuel produces 25 times more energy than is used in the diffusion process, while centrifuge-produced fuel produces 1,500 times more energy than is used in the centrifuge process.
In addition to its use in enrichment, uranium hexafluoride has been used in an advanced reprocessing method (fluoride volatility), which was developed in the Czech Republic. In this process, spent nuclear fuel is treated with fluorine gas to transform the oxides or elemental metals into a mixture of fluorides. This mixture is then distilled to separate the different classes of material. Some fission products form nonvolatile fluorides which remain as solids and can then either be prepared for storage as nuclear waste or further processed either by solvation-based methods or electrochemically.
Uranium enrichment produces large quantities of depleted uranium hexafluoride (DTemplate:Chem2 or D-Template:Chem2) as a waste product. The long-term storage of D-Template:Chem2 presents environmental, health, and safety risks because of its chemical instability. When Template:Chem2 is exposed to moist air, it reacts with the water in the air to produce Template:Chem2 (uranyl fluoride) and HF (hydrogen fluoride) both of which are highly corrosive and toxic. In 2005, about 686,000 tonnes of D-Template:Chem2 was housed in 57,122 storage cylinders located near Portsmouth, Ohio; Oak Ridge, Tennessee; and Paducah, Kentucky.[13][14] Storage cylinders must be regularly inspected for signs of corrosion and leaks. The estimated lifetime of the steel cylinders is measured in decades.[15]
Accidents and disposal
There have been several accidents involving uranium hexafluoride in the US, including a cylinder-filling accident and material release at the Sequoyah Fuels Corporation in 1986 where an estimated 29,500 pounds of gaseous Template:Chem2 escaped.[16][17] The US government has been converting DTemplate:Chem2 to solid uranium oxides for disposal.[18] Such disposal of the entire DTemplate:Chem2 stockpile could cost anywhere from $15 million to $450 million.[19]Script error: No such module "Gallery".
↑J. C. Taylor, P. W. Wilson, J. W. Kelly: „The structures of fluorides. I. Deviations from ideal symmetry in the structure of crystalline UF6: a neutron diffraction analysis", Acta Crystallogr., 1973, B29, p. 7–12; Script error: No such module "doi"..
