Uranium-236 enrichment

The balance of hydrogen fluoride is used ia appHcations such as stainless steel pickling inorganic fluoride production, alkylation (qv), uranium enrichment, and fluorine production. Hydrogen fluoride is used to convert uranium oxide to UF which then reacts with elemental fluorine to produce volatile UF. ... 

Gaseous diffusion cascades for uranium enrichment have also been built in the United Kingdom, France, the former USSR, China, and, more recendy, in Argentina. 

S. ViUani, ed.. Uranium Enrichment, Topics in MppliedPhysics, Vol. 35, Springer-Vedag, New York, 1979. 

MO fuel designed for use in existing LWRs is typically exposed to bum-ups greater than 40 x 10 MW-d/t. The discharged MO fuel has essentially the same uranium enrichment as uranium oxide fuel, but has a greater total amount of plutonium. 

Uranium oxide [1344-57-6] from mills is converted into uranium hexafluoride [7783-81-5] FJF, for use in gaseous diffusion isotope separation plants (see Diffusion separation methods). The wastes from these operations are only slightly radioactive. Both uranium-235 and uranium-238 have long half-Hves, 7.08 x 10 and 4.46 x 10 yr, respectively. Uranium enriched to around 3 wt % is shipped to a reactor fuel fabrication plant (see Nuclear REACTORS, NUCLEAR FUEL reserves). There conversion to uranium dioxide is foUowed by peUet formation, sintering, and placement in tubes to form fuel rods. The rods are put in bundles to form fuel assembHes. Despite active recycling (qv), some low activity wastes are produced. 

In plutonium-fueled breeder power reactors, more plutonium is produced than is consumed (see Nuclearreactors, reactor types). Thus the utilisa tion of plutonium as a nuclear energy or weapon source is especially attractive to countries that do not have uranium-enrichment faciUties. The cost of a chemical reprocessing plant for plutonium production is much less than that of a uranium-235 enrichment plant (see Uranium and uranium compounds). Since the end of the Cold War, the potential surplus of Pu metal recovered from the dismantling of nuclear weapons has presented a large risk from a security standpoint. 

Refining to a High Purity Product. The normal yeUowcake product of uranium milling operations is not generaUy pure enough for use ia most nuclear appHcations. Many additional methods have been used to refine the yeUowcake iato a product of sufficient purity for use ia the nuclear iadustry. The two most common methods for refining uranium to a high purity product are tributyl phosphate (TBP) extraction from HNO solutions, or distiUation of UF, siace this is the feedstock for uranium enrichment plants. 

National Research Council (U.S.). Committee on Decontamination and Decommissioning of Uranium Enrichment Affordable Cleanup ... 

Opportunities for Cost deduction in the Ttecontamination and Decommissioning of the Nation s Uranium Enrichment Facilities,V3.tLoaA Academy Press, Washington, D.C., 1996. 

Production in Fission of Heavy Elements. Tritium is produced as a minor product of nuclear fission (47). The yield of tritium is one to two atoms in 10,000 fissions of natural uranium, enriched uranium, or a mixture of transuranium nucHdes (see Actinides and transactinides Uranium). 

D. G. Avery and E. Davies, Uranium Enrichment by Gas Centrifuge Mills Boon Ltd., London, 1973. 

Uranium Information Centre, Ltd. (1997). Uranium Enrichment. Melbourne Author. 

Another, more modern, route of processing the yellow cake is shown in Figure 5.38, accomplishes the production of enriched uranium oxide entirely by pyroprocessing. Thus, uranium is finally obtained in three forms metallic uranium, enriched uranium dioxide, and natural uranium dioxide. As the flowsheet shows, and as briefly described herein, these are essentially the products of hydro and pyro-based processing schemes. 

Enrichment, Isotopic—An isotopic separation process by which the relative abundances of the isotopes of a given element are altered, thus producing a form of the element that has been enriched in one or more isotopes and depleted in others. In uranium enrichment, the percentage of uranium-235 in natural uranium can be increased from 0.7% to >90% in a gaseous diffusion process based on the different thermal velocities of the constituents of natural uranium (234U, 235U, 238U) in the molecular form UF6. 

In the last twenty odd years, almost all nuclear endeavors in the U.S. have run into bureaucratic and litigious delays, making their schedules and costs unpredictable. In addition to reactor construction, there are the bureaucratic delays in the waste repository programs. Another example is the attempt to build a new uranium enrichment plant in the state of Louisiana, a plant which uses advanced technology demonstrated in several countries in Europe. Licensing started over seven years ago and is still held up by issues without relevance to technology or safety. It is approaching the point where the delays, and costs may lead to the abandonment of a potential asset... 

Uranium carbonates, 25 430-432 Uranium chlorides, 25 438-439 Uranium compounds, 25 421-434 handling, 17 529 Uranium dioxide, 25 422-423 Uranium-enrichment process gas centrifuge, 25 413-415 Uranium exploration, 25 398 URanium Extraction (UREX) process, 25 420... 

Fishman, A. M. A. I. Chem. E. Symposium Series No. 169, 73 (1977). Developments in Uranium enrichment, 43. The centar gas centrifuge enrichment project Economics and engineering considerations. 

Fig. 8.2 Gaseous diffusion cell for uranium enrichment, schematic (http //www.globalsecuiity.

Fig. 8.4 Ideal cascade for uranium enrichment. The height of each section is roughly proportional to the number of stages in that section and the width at any stage to the amount of material being processed in that stage (Modified from Spindel in Rock, P. A., ACS Symposium Series 11. Isotopes and Chemical Principles 1975)...

Fig. 8.12 Schematic cross section of a supersonic nozzle isotope separator of radial design (Modified from Becker, E. W. Uranium Enrichment, Villani, S.,...

Uranium enrichment using LIS has been exhaustively studied and the conceptual outlines of two different methods can be found in the open literature. These methods are multi-photon dissociation of UF6 (SILEX, or Separation of Isotopes by Laser Excitation) and laser excitation of monatomic uranium vapor (Atomic Vapor Laser Isotope Separation, or AVLIS). Following an enormous investment, AVLIS was used by the United States DOE in the 1980s and early 1990s, but due to the present oversupply of separated uranium, the plant has been shut down. 

Avery, D. G., Davies, E., 1973 Uranium Enrichment by Gas Centrifuge (London, Mills Boon, Ltd.)... 

Many aspects of the development of uranium enrichment membranes were, and to a large extent still are classified, the scanty traces in the public domain only being a number of patents (CEA 1958, Clement, Grangeon and Kayser 1973, Miszenti and Mannetti 1971, Veyre et al. 1977). Much of the work done at present to develop new and improved inorganic membranes is also more or less classified. 

After the oil crisis in 1973, the need for large enrichment capacities for supply of fuel to the nuclear power plants became obvious and several European countries (Belgium, France, Italy and Spain) decided to build the huge Eurodif gas diffusion plant. This plant is located in France, in the Rhone valley, a few kilometers away from the Pierrelatte plant. Simultaneously, England, West Germany and the Netherlands (the Troika) chose to jointly develop the centrifugation process for uranium enrichment, which does not use membranes. 

The enrichment capacity of Eurodif is 10,800,(XX) UTS (units of separation work). This corresponds to the fuel consumption of 90 nuclear reactors of the 900 MW class. In view of all the programs for building nuclear power plants hastily set up by many countries shortly after the 1973 oil crisis, it was clear that another uranium enrichment plant of similar size would have to be built immediately after Eurodif was completed. This was the Coredif project. 

In today s world, it is obvious that uranium enrichment by Knudsen diffusion has no future. Uranium enrichment by using laser technology can be accomplished much more efficiently. Such plants are expected to be ready for industrial-scale production by the year 2000 or 2005, when, according to current estimates, new uranium enrichment plants will be needed. 

This concept later evolved into the Ucarsep membrane made of a layer of nonsintered ceramic oxide (including Zr02) deposited on a porous carbon or ceramic support, which was patented by Union Carbide in 1973 (Trulson and Litz 1973). Apparently, the prospects for a significant industrial development of these membranes were at the time rather limited. In 1978, Union Carbide sold to SPEC the worldwide licence for these membranes, except for a number of applications in the textile industry in the U.S. At that time, SPEC recognized the potential of inorganic membranes, but declassification of the inorganic membrane technology it had itself developed for uranium enrichment was not possible. 

Ceraver s entry into the microfiltration and ultrafiltration field followed a completely different approach. In 1980, it became apparent that the type of product made by Ceraver for uranium enrichment, which was a tubular support and an intermediate layer with a pore diameter in the microfiltration range, might be declassified. Ceraver therefore developed a range of a-AljOj microfiltration membranes on an a-AljOs support with two key features first, the multichannel support and second, the possibility to backflush the filtrate in order to slow down fouling. 

A completely different type of inorganic membrane also has its origin in the nuclear industry the asymmetric alumina membranes obtained by the anodic oxidation of an aluminum sheet were first developed for uranium enrichment... 

In summary, the development of inorganic membranes was initially oriented towards uranium enrichment which is still by very far their most significant application. Some of the key participants involved in the nuclear programs further developed them into cross-flow filtration membranes. The recent years have seen the start of a much broader exploration of the manyfold potentialities of inorganic membranes, both in terms of materials and applications. Thus, a multifaceted new field of technology is emerging. 

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