Depletion
Depletion is a term used in nuclear technology . It generally refers to the removal of one or more isotopes of a chemical element from the natural isotope mixture. Although this term is commonly associated with uranium, the technique of waste depletion, which results in enrichment in the actual product, is also used for other elements, e.g. B. for the separation of heavy hydrogen ( deuterium ).
Depleted uranium
The best-known depleted product is depleted uranium called Tails , also known as DU ( depleted uranium ); this is uranium, in which the proportion of the fissile isotopes 234 U and 235 U is lower than in the naturally occurring isotope mixture. It is a waste product of uranium enrichment . With the enrichment of about 3% 235 U, which is usual for power plant fuel rods, about 5.5 tons of depleted uranium are produced in today's enrichment plants per ton of nuclear fuel.
Because of its low price as a waste product in connection with a very high density - about 19.2 g / cm³ compared to 7.85 g / cm³ for steel and 11.34 g / cm³ for lead ; Tungsten is just as dense as depleted uranium, but much more expensive - it is used as uranium ammunition in armor-piercing projectiles, which, due to their uranium core, have a high mass and therefore enormous penetration power due to their small size. Using depleted uranium makes them less radioactive than previous uranium projectiles that contained undepleted uranium. These projectiles were used to a greater extent in the US war against Iraq and during the Kosovo war in 1998/99. Furthermore, until the discussion that had been triggered by the crash of a cargo plane in Amsterdam ( El-Al flight 1862 ), depleted uranium was used for counterweights in aircraft construction. Uranium was used so that the weights take up as little space as possible. To avoid contamination and radiation exposure , the uranium was welded into a housing made of sheet steel or aluminum.
However, only a small part of the accumulated depleted uranium could be used for these applications. Around 95% of the depleted uranium accrued to date, estimated around 1.1 million tons worldwide, is still stored in the form of uranium hexafluoride (UF 6 ) in large, special steel tanks, mostly (but not exclusively) in the immediate vicinity of the enrichment facilities in which it originally occurred. This type of interim storage is officially approved by the IAEA and can be continued until the depleted uranium is put to use. However, it should be viewed critically that uranium hexafluoride reacts very violently with water and forms toxic hydrofluoric acid as a reaction product .