Uranium dioxide spent nuclear fuel

It is apparent from the foregoing discussion that both ILs and supercritical carbon dioxide do indeed offer promise as alternative solvents in the reprocessing of spent nuclear fuel and the treatment of nuclear wastes. It is equally apparent, however, that considerable additional work lies ahead before this promise can be fully realized. Of particular importance in this context is the need for an improved understanding of the fundamental aspects of metal ion transfer into ILs, for a thorough evaluation of the desirability of extractant functionalization of ILs, and for the development of new methods for both the recovery of extracted ions (e.g., uranium) and the recycling of extractants in supercritical C02-based systems. Only after such issues have been addressed might these unique solvents reasonably be expected to provide the basis of improved approaches to An or FP separations. 

These mixed oxides can also be manufactured by mixing the uranium and nitrate solutions produeed during the reprocessing of spent nuclear fuels and converting these metal nitrate mixtures into a mixed oxide (coprecipitation). In this process the plutonium is first reoxidized, then gaseous ammonia and carbon dioxide are introduced into the aqueous nitrate mixture, whereupon ammonium uranyl-plutonyl carbonate is precipitated. This can be calcined to... 

Oversby, V. M. 1999. Uranium Dioxide, SIMFUEL, and Spent Fuel Dissolution Rates - A Review of Published Data. Swedish Nuclear Fuel and Waste Management Co., Stockholm, Sweden, TR-99-22. 

Nuclear power plants in the United States use light water moderated nuclear reactors (LWR) that produce the steam to generate electricity. The fuel elements for boiling water reactors and pressurized water reactors (PWR) are nearly the same. The fuel is uranium dioxide enriched with 3 % and this produces a nearly uniform spent fuel, which would be the feed for domestic fuel reprocessing. 

Spent fuel rods from nuclear power stations are a major source of nuclear waste. Nuclear fuel is composed of uranium dioxide, UO2. After some years of use, when 1—4% of the uranium has undergone fission, the performance of the fuel rods falls, and these are then replaced. The spent fuel rods consist of uranium dioxide together with fission products. 

Several hundred uranium dioxide fuel assemblies make up the core of a reactor. For a reactor with an output of 1,000 MWe, a typical core contains about 75 t of low-enrichment uranium ( 3.5% U). During the operating cycle of a nuclear reactor, several competing processes determine the final radionuclide inventory in the spent fuel. These processes are... 

Due to the current low costs of natural uranium and uranium enrichment, the use of uranium dioxide fuel with postponed reprocessing and spent fuel storage on the nuclear power plant site, are economically preferable for SVBR-75/100 at the moment. The duration of the benefits of this fuel cycle option depends on the available uranium resources and nuclear power deployment scale. In any case, the existing uranium resources are sufficient to achieve the realistic scenario of nuclear power development until the year 2050. The costs of natural gas could be expected to increase more intensively than the costs of natural uranium. This will ensure the NPP competitiveness even with a considerable increase in uranium prices, because the structure of electricity cost is different for NPPs and fossil-fuelled heat power plants. 

Nuclear energy, which is obtained when nucleons (protons and neutrons) are allowed to adopt lower energy arrangements and to release the excess energy as heat, does not contribute to the carbon dioxide load of the atmosphere, but it does present pollution problems of a different land radioactive waste. Optimists presume that this waste can be contained, in contrast to the burden of carbon dioxide, which spreads globally. Pessimists doubt that the waste can be contained—for thousands of years. Nuclear power depends directly on the discipline of chemistry in so far as chemical processes are used to extract and prepare the uranium fuel, to process spent fuel, and to encapsulate waste material in stable glass blocks prior to burial. Nuclear fusion, in contrast to nuclear fission, does not present such serious disposal-related problems, but it has not yet been carried out in an economic, controlled manner. 

Bruno, J., Casas, L, Cera, E., De Pablo, J., Gimenez, j. Torrero, M. E. 1995. Uranium (IV) dioxide and simfuel as chemical analogues of nuclear spent fuel matrix dissolution. A comparison of dissolution results in a standard NaCl/ NaHCOi solution. In Murakami, T. Ewing, R. C. (eds) Scientific Basis of Nuclear Waste Management, XVIII, 601-608. 

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