Uranium trioxide production

An initial charge of several hundred kilograms of uranium trioxide is fed into the reactor from a storage hopper, the first charge having been produced in a small pilot plant. The uranium trioxide product is withdrawn... 

Me Kibben, J.M. 1976. Explosion and fire in the uranium trioxide production facilities at the SRS plant on February 12,1975, E.I DuPont SRS DPSU 76-11-1. Aiken, SC Savannah River Plant. 

Since the uranium from the milling process is still in an unusable form, the yellow cake is broken down once again. The uranium trioxide is reduced to uranium dioxide at veiy high temperatures. Refining of the product also takes place. Now the uranium product consists almost entirely of UO,. 

The aerosol by-products of exploded DU munitions are primarily the uranium oxides with varying dissolution rates. Uranium trioxide (UO3) is soluble like uranyl salts, and systemic absorption accounts for more than 20% of the exposure burden, with 20% of the excreted uranium being in the urine (Morrow et al, 1964, 1972, 1982). UO3, being soluble, has a fast dissolution rate (Type F), and is rapidly removed from the lung (half-life of 4.7 days). Uranium... 

Uranium Trioxide, Uranic Oxide, Uranic Anhydride, or Uranyl Oxide, UO3, is obtained when uranic acid, ammonium diuranate, or ammonium uranyl carbonate is heated to a temperature not exceeding 300° Cd When uranyl nitrate is similarly heated the product always contains basic nitrate, but if this product is heated in a current of oxygen at 500° C. it yields pure uranium trioxide. ... 

Uranium trioxide is a key precursor to UF4 and UFg, which are used in the isotopic enrichment of nuclear fuels. It is also used in the production of UO2 fuel, and microspheres of UO3 can themselves be used as nuclear fuel. Fabrication of UO3 microspheres has been accomplished using sol-gel or internal gelation processes.Finally, UO3 is also a support for catalytic oxidative destructive of organics. 

Uranium trioxide or uranic oxide, UOs, may be prepared in pure form by long continued heating of uranyl-ammonium carbonate at 300° or of ammonium uranate at 250° uranyl nitrate also yields UOs on ignition, but the product contains basic nitrates unless the heating is done thoroughly. The color of the oxide varies from orange to red, depending on the method... 

The process of calcination of oxides, hydrogen reduction of oxides to lower oxides, hydrofluorination and hydrochlorination of oxides, etc., can often be carried out by conventional chemical engineering methods. However, the high standards of purity usually required for rare metal extraction at least necessitate novel materials of construction. In addition, a considerable development and pioneering effort has been devoted to the improvement of these techniques, particularly applied to the intermediates in the production of uranium metal, uranium trioxide, dioxide and tetrafluoride. It is possible, therefore, that the resulting processes can be more widely employed in the rare metal extraction field in the future. 

The uranium trioxide feed passes to the reduction reactor by means of a reciprocating feeder. The dioxide product is metered in a suitable vessel after withdrawal from the reactor. A special type of poppet valve is used on these lines conveying solids. 

With regard to UO2 conversion supply, Cameco s plant is by far the largest supplier, with a licensed annual capacity of 2800 tU. In addition, smaller plants exist to meet the local needs in India, Argentina, and Romania. Cameco Corporation owns and operates ma-nium refinery and conversion facilities located respectively at Blind River and Port Hope. The Blind River plant refines natural uranium concentrates (U3O8) into uranium trioxide (UO3) and was commissioned in 1983. The intermediate product is shipped to the Port Hope plant (commissioned 1984) where further processing produces natural UFg. 

At a conversion facility, uranium trioxide is converted into a specific uranium end product according to the nuclear power reactor class. Actually, there are three uranium compounds used in nuclearpower reactors ... 

Alternatively, the uranium concentrate may be treated with nitric acid and fed to an extraction column, the eventual product being uranyl nitrate hexahydrate. This is then decomposed by heating to form uranium trioxide, UO3 ( organe oxide ). By reaction with hydrogen in a fluidized-bed reactor, the UO3 is reduced to UO2, which is of sufficient purity to be used directly in the fabrication of natural uranium oxide fuel elements. 

Fodor, M., Z. Poko, and J. Mink, 1966. Investigation of hydrolysis products from uranium trioxide and uranyl salts by derivatography and infrared spectroscopy. Mikrochim. Acta 865. 

Tc is available through the /l -decay of Mo (Fig. 2.1.B), which can be obtained by irradiation of natural molybdenum or enriched Mo with thermal neutrons in a nuclear reactor. The cross section of the reaction Mo(nih,v) Mo is 0.13 barn [1.5], Molybdenum trioxide, ammonium molybdate or molybdenum metal are used as targets. This so-called (n,7)-molybdenum-99 is obtained in high nuclidic purity. However, its specific activity amounts to only a few Ci per gram. In contrast, Mo with a specific activity of more than in Ci (3.7 10 MBq) per gram is obtainable by fission of with thermal neutrons in a fission yield of 6.1 atom % [16]. Natural or -enriched uranium, in the form of metal, uranium-aluminum alloys or uranium dioxide, is used for the fission. The isolation of Mo requires many separation steps, particularly for the separation of other fission products and transuranium elements that arc also produced. 

Weiss and Downs described the use of vanadium pentoxide for the catalytic oxidation of toluene and naphthalene. Subsequently, Graver suggested a mixed oxide catalyst derived from uranium oxide and molybdenum trioxide in molar ratios ranging from 3-13 1. Copper oxide was also suggested as a possible promoter. When using the vanadium pentoxide catalyst, benzoic acid was the main product at temperatures below 400°C, with some benzaldehyde formed at higher temperatures. Selectivity was only about 50% at 5% conversion. 

---