Yellowcake
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Yellowcake ( English 'yellow cake' or 'yellow cake') is a powdery mixture of uranium compounds . The name comes from the original yellow color of the powder from earlier manufacturing processes. Due to the higher temperatures used today to process uranium ore , modern yellow cake is actually more brown to black.
Uranium ore contains up to 0.1% uranium in the form of oxides. After ore mining, the first processing stage is the production of yellow cake. The uranium oxides can be extracted from the mined ore with acids. About one kilogram of yellow cake is extracted from two tons of mined ore in uranium mills. It consists of more than 80% uranium compounds.
Yellowcake is the raw material for the manufacture of fuel elements . The further processing steps depend on the type of reactor in which the uranium is to be used. If enrichment is required, yellow cake is converted in a chemical process into uranium hexafluoride (UF 6 ), which is crystalline under normal conditions and gaseous from 56 ° C. Otherwise it is processed into uranium dioxide or uranium metal .
The residues from the extraction of yellow cake (so-called tailings ) are still radioactive despite the uranium separation and must therefore be properly disposed of. Because of their large amount and the long half-life of the remaining thorium , radium and uranium isotopes , they represent an environmental problem for a long time. The contamination of the groundwater is particularly problematic .
literature
- Donald M. Hausen: Characterizing and Classifying Uranium Yellow Cakes: A Background , in: JOM , 1998 , 50 (12), pp. 45-47; doi : 10.1007 / s11837-998-0307-5 ; bibcode : 1998JOM .... 50l..45H .
Individual evidence
Web links
- For the problem of "extraction of yellow cake" see the film Uranium - is it a Country?
- Documentary Yellow Cake: The Lie of Clean Energy , 2010 by Joachim Tschirner
- chemie-master.de, photo Yellowcake