Spent nuclear fuel from pressurized water reactors represents a valuable nuclear material, since it still has a higher content of 235U than natural uranium, moreover, there are also new fission isotopes 239Pu and 241Pu. That is why some countries reprocess SF. The result is a new nuclear fuel and highly active residues. In this way spent nuclear material returns back to the fuel cycle and it is energetically effectively used. One ton of reprocessed nuclear fuel represents saving of two tons of natural uranium.

Reprocessing of spent nuclear fuel represents a complex chemical process serving for separation of uranium from plutonium and removal of fission products. Before its execution it is necessary to store SF for several months to years in basins, while expressive decrease of activity of the fission products with the short half-life period takes place.

At present time several tens of technological methods of SF reprocessing are elaborated. In practice, the most prevalent is the purex method (PUREX — Plutonium Uranium Extraction). High radioactivity of fuel forces the whole reprocessing process to be executed by remote controlled manipulators and robots. First protective film made of zircon is removed from fuel assemblies. Spent fuel is dissolved in nitric acid and individual components are chemically separated from this solution. Resulting effect of the reprocessing process is uranium, which is in form of oxide or hexafluoride, and plutonium, usually as oxide. Plutonium and uranium will be further used as fuel for different types of reactors. The remains of metallic cladding of fuel rods are processed as a middle active waste. Fission products are concentrated by evaporation, they are temporarily stored in a liquid form, and they are fixated before their final storage, usually by vitrification. In this way only 115 liters of highly active waste originate from one ton of SF in vitrificated form.

Only economically strong countries can afford reprocessing. Commercial reprocessing plants are for example in La Hague and in Marcoule in France, in Sellafield in Britain, Tokai-Mura in Japan and also reprocessing complex Majak in Ural is well known. Capacity of these plants makes it possible to reprocess only a smaller part of SF from present nuclear power plants, however, other plants are under construction. But, at present time, offer of reprocessing exceeds the demand for it. Reprocessing is executed on the base of commercial contracts, while the customer can be also from abroad. However, it is true in all the cases that the customer receives back not only material for new fuel, but also highly active remains, he has to take care of in due course.