Uranium Fuel

The raw material for nuclear reactor fuel, uranium, exits the mining—milling sequence as uranium oxide. Because of its color, it is called yellow cake. The yellow cake is converted to uranium hexafluoride and enriched in 235u... 

The main technological uses for UO2 are found in the nuclear fuel cycle as the principal component for light and heavy water reactor fuels. Uranium dioxide is also a starting material for the synthesis of UF [10049-14-6] 6 (both critical for the production of pure uranium metal and... 

One of the many problems of nuclear power is the availability of fuel uranium-235 reserves are only about 0.7% those of the nonfissile uranium-238, and the separation of the isotopes is costly (Section 17.12). One solution is to synthesize fissile nuclides from other elements. In a breeder reactor, a reactor that is used to create nuclear fuel, the neutrons are not moderated. Their high speeds result in... 

Catalyst in alkylation and polymerization reactions Additives to liquid rocket fuels Uranium refining Cyclosarin (GF) 9.01... 

Uranium-235 is the most important uranium isotope for nuclear fuel. Uranium-238, although not fissionable itself, can be converted into the fissionable plutonium-239 in a breeder reactor by the following nuclear reaction ... 

Uranium is best known as a fuel for nuclear power plants. To prepare this fuel, uranium ores are processed to extract and enrich the uranium. The process begins by mining uranium-rich ores and then crushing the rock. The ore is mixed with water and thickened to form a slurry. The slurry is treated with sulfuric acid and the product reacted with amines in a series of reactions to give ammonium diuranate, (NH4)2U20 . Ammonium diuranate is heated to yield an enriched uranium oxide solid known as yellow cake. Yellow cake contains from 70—90% U3Og in the form of a mixture of U02 and U03. The yellow cake is then shipped to a conversion plant where it can be enriched. 

Fig. 7.1. Schematic presentations of (a) the once-through cycle (b) the thermal reactor cycle and (c) the fast reactor cycle. UjO, = yellowcake, UF = uranium hexafluoride, MOX = mixed oxide fuel (uranium/...

Although not used as a reactor fuel, uranium mononitride (UN) possesses desirable properties a face-centered-cubic NaCl structure, a high melting point (2850°C for... 

Similarly, the nuclear fuel uranium-233 can be made when ordinary thorium. (Th-232) captures a neutron to produce thorium-233 the thorium-233 decays to produce uranium-233. 

B. Depleted Uranium (DU). During the enrichment process for nuclear fuel, Uranium-235 is removed from uranium ore. The by-product of this process is DEPLETED URANIUM (DU). The US Army and many other nations use DU in armor and munitions. As used by the US Army, DU is typically about 98.8% Uranium-238, 0.2% Uranium-235, and 0.0006% Uranium-234. The external radiation hazard from DU is roughly 40% less than an equal amount of natural uranium. 

The production of power from controlled nuclear fission of heavy elements is the most important technical application of nuclear reactions at the present time. This is so because the world s reserves of energy in the nuclear fuels uranium and thorium greatly exceed the energy reserves in all the coal, oil, and gas in the world [HI], because the energy of nuclear fuels is in a form far more intense and concentrated than in conventional fuels, and because in many parts of the world power can be produced as economically from nuclear fission as from the combustion of conventional fuels. 

The uranium and plutonium complexes are strong enough to remain in the organic phase during stripping. In reprocessing LWR fuel, uranium is mainly affected because of its great... 

The energy sources considered for distillation are fossil fuels, uranium... 

CHEMICAL PROPERTIES nonflammable gas contains odd number of electrons and is paramagnetic combines with oxygen to form nitrogen dioxide (NO2), a brown gas combines with chlorine and bromine to form the nitrosyl halides, such as nitrosyl chloride (NOCl) reacts with water to form nitric acid rapidly converted in air to nitrogen dioxide reacts with boron, carbon disulfide, chlorine monoxide, chromium, fluorine, fuels, uranium hydrocarbons, nitrogen trichloride, and phosphine FP (NA) LFL/UFL (NA) AT (NA) HF (-21.5 kcal/mole at 18°C) HK 2.3 kJ/mol at 109.5 K). 

Since UO2 is the most common uranium oxide found in nuclear fuels, uranium extraction from UO2 is indispensable in the nuclear fuel reprocessing and uranium waste treatment. From solid UO2, however, uranium extraction is not possible with this method because TTA nor TBP form complexes with UO2 directly. If we introduce acid homogeneously in SF-CO2, we can expect UO2 dissolution and conversion into U02, which can be complexed with TBP by the charge neutralization as TBP2U02(N03)2. For example, concentrated nitric acid is widely used to dissolve UO2 in aqueous solution forming U02(N03)2. 

Fuel Uranium metal. To conserve neutrons and allow ... 

Fuel Uranium dioxide In stainless steel cladding. Moderator Graphite. 

Fuel Uranium dioxide clad in an alloy of zirconium (Zircaloyl. 

There are several different kinds of nuclear reactors that use diverse types of fuel (uranium compounds) that are placed in different sorts of fuel elements and these in turn are arranged in varions fuel assemblies. A detailed survey of these is beyond the scope of this book however an elementary understanding of nuclear fuel and its characterization is highly relevant. Figure 1.14 depicts the main nuclear reactor, types of fuel, moderator, and coolants in service. 

When comparing the data for the two different types of fuel, uranium fuel and mixed-oxide fuel, one can see the main differences in the region of the lighter platinum elements ruthenium, rhodium and palladium where the higher fission yields in the Pu fission lead to higher concentrations of these elements in the irradiated mixed-oxide fuel. 

Fuel Uranium-zirconium metal-ceramic (cermet) ... 

The use of a fuel (uranium dioxide in a silumin matrix) with the enrichment by not more than 20 weight % ... 

Cermet fuel (uranium dioxide in silumin matrix) ... 

Type of fuel Uranium dioxide. The core is based on micro fuel elements of 1.8 mm outer diameter. The diameter of UO2 kernel is 1.4 mm, the cumulative thickness of a multi-layer coating is 0.2 mm... 

As for electricity from wind and directly from the sun, development will be more dispersed than is common practice with conventional fuels such as the fossil fuels, uranium, and hydropower. In each case today, electricity is generated at large centralized power plants. If either wind or solar electricity is to become a significant contributor in the near future, it will be generated from a dispersed network of decentralized smaller power plants. Likewise, the impacts from these activities will also be dispersed. 

The georeactor, as it is now called, is comparably simple in structure, as shown schematically in Fig. 123.1. Thought to reside within the inner core at the center of the earth, the georeactor sub-core consists of the actinide fuel, uranium and the heaver fissionable elements, such as plutonium, formed by the breeding process. 

There is currently a lot of interest worldwide in the development and deployment of modular high temperature gas cooled reactors. Besides in China, similar design and technology development activities are underway in France, Japan, Russia, South Africa, the USA, etc. [XVII-5-7]. Main differences between the programmes are related to fuel technology (pebble fuel versus prismatic fuel, uranium versus plutonium) and to power conversion technology (steam turbine versus gas turbine). 

The maximum possible uranium density (the reference fuel noted previously) was found to be less than the densities assumed in Sect. 4.1.1. To achieve a C/ U ratio of 50, an enrichment of 11% would be required rather than the value of 8.4 reported in Table 4.1. To achieve a C/ U ratio of 20, an enrichment of 27% would be required rather than the value of 9.0 reported in Table 4.1. Note that Table 4.1 shows that the mass of uranium required for a C/ U ratio of 50 is 21 times greater than the amount required at a C/235u ratio of 20. An eeonomic assessment of the cost of these two fuels revealed that the cost of fuel for the lower C/ U ratio was more than a factor of 10 less than that for the higher ratio. Furthermore, the significant increase in core mass and thus an increase in transportation costs for moving the reactor from the production to deployment site seemed to make it apparent that the C/ U ratio should be kept to the minimum possible value. Because it is the policy of the United States that fuel for reactors deployed outside the borders of the United States have an enrichment no greater than 20 wt % U, the value of 20% enrichment at the reference fuel uranium density would provide the lowest possible C/ U ratio. The assumption of 20% enriched uranium leads to a C/ U ratio of 39.28 (based on an assumed density for UC2 of 13.63 g/cm ). 

Pebble bed and prismatic reactor are the two major design variants. Both are in use today. In either case, the basic fuel construction is the TRISO-coated particle fuel. Uranium, thorium, and plutonium fuel cycle options have been investigated and some have been operated in the reactors. Spent fuel may be direct disposed or recycled. The unique constmction and high bumup potential of the TRISO fuel enhances proliferation resistance. 

Reactor type Main countries Number GWe Fuel Uranium enrichment, wt% Coolant/ moderator Neutron spectrum... 

The Plutonium Recycle Program concentrated mainly on mixed oxide fuels (uranium and plutonium) however, some efforts were devoted to the fabrication and testing of zircaloy-cladded, plutonium-aluminum fuels in the Plutonium Recycle Test Reactor and the Experimental Boiling Water Reactor at the INEL. 

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