Alloys with uranium

A series of zirconium- and titanium-base alloys have been prepared as possible clad materials. These alloys are of interest because they do not form low melting point alloys with uranium, as do the iron- and nickel-base alloys. The thermal conductivities of several of these alloys have been measured, and they have been found to be quite low. The investigation of possible clad materials including the re-evaluation of iron- and nickel-base alloys under anticipated conditions of operation, is continuing. 

Alloys with Yttrium compounds Uranium compounds Plutonium compounds ... 

Electrometric Methods have been applied for the estimation of vanadium alone and alloyed with other metals, e.g. iron, chromium, uranium. The reduced solution is either gradually oxidised by means of a suitable oxidising agent (potassium permanganate, ammonium persulphate, nitric acid), or the vanadate solution is gradually reduced with ferrous sulphate solution the changes in the E.M.F. of a suitable cell indicate the end point.8... 

The fuel which was used in these SSBNs is based on a UZr metallic alloy with highly enriched uranium for which no reprocessing process has been developed. 

Metallurgically, uranium metal may exist in three allotropic forms orthorhombic, tetragonal, or body-centered cubic (EPA 1991), and may be alloyed with other metals to alter its structural and physical properties to suit the application. Like aluminum metal powder, uranium metal powder is autopyrophoric and can burn spontaneously at room temperature in the presence of air, oxygen, and water. In the same manner, the surface of bulk metal, when first exposed to the atmosphere, rapidly oxidizes and produces a thin surface layer of UO2 which resists oxygen penetration and protects the inner metal from oxidation. 

Pyrophoric Uranium.—It has already been mentioned (p. 278) that uranium, in a very finely divided condition, takes fire on exposure to air. The black powder obtained by reduction of the oxide by means of magnesium exhibits this property. Chesneau observed that the sparks detached from uranium by friction with hard steel would ignite mixtures of methane and air, as well as such inflammable liquids as alcohol and benzene, and he concluded that their temperature could not be below 1000° C. The jjroduct obtained by Eeree (see p. 279) by heating uranium amalgam in vacuo burned spontaneously in the air. Alloys of uranium and iron containing more than 20 per cent, of uranium are pyrophoric, the activity increasing with increase in uranium content. 

Another potential use for holmium is a result of its very unusual and strong magnetic properties. It has been used in alloys with other metals to produce some of the strongest magnetic fields ever produced. Holmium also has some limited use in the manufacture of control rods for nuclear power plants. Control rods limit the number of neutrons available to cause the fission of uranium in nuclear reactors, thus controlling the amount of energy produced in the plant. 

The necessary nonproliferation constraints are provided by the high radioactivity of each product stream, and the remote handling requirement of each process step. In addition, both the fissile uranium and plutonium are coprocessed with thorium. Pure plutonium cannot be obtained because both thorium and plutonium have a large solubility in the solvent alloy. Pure uranium could in principle be obtained by repeatedly washing the uranium-... 

Standard penetrator material [6.29]. Nevertheless, recent environmental considerations have put a strong emphasis on substituting depleted uranium by heavy metals because of its radioactivity. Efforts to improve the ballistic performance through proper processing and compositional modifications have failed [6.29,6.39]. Recent research has therefore focused on alternative matrix alloys, such as tungsten-hafhium, tungsten-uranium composites [6.29], or heavy metal alloys with a spiculating core of WC [6.41]. 

The dithizone method has been applied in determining cadmium in food products [12], natural waters [19], organic materials [76], zinc sulphide [23], beryllium [17], zirconium alloys [8], uranium compounds [77], Cd-Se and Cd-Te thin films [78]. The flow-injection technique (FIA) has also been applied in determining Cd with dithizone [79,80]. 

The thiocyanate method has been used for determining niobium in steels [35,118], tantalum and its compounds [6,7,119], cobalt alloys [37], uranium [120], rocks and minerals [1,121], sodium metal [122], and thin Nb-Ti films [123]. Niobium has been determined in various metals and alloys with the use of Bromopyrogallol Red [124]. 

Zireonium has been determined in niobium by using Pyrocatechol Violet [71]. Hafnium has been determined in uranium alloys with the use of PAN [27]. 2-(2-Pyridylmethylenamino)phenol has been applied for determination of Zr in the presence of Cr (in bronzes) by derivative spectrophotometry [108]. 

As the third most abundant metal in Earths crust, calcium is widespread in a large number of mineral deposits, relatively inexpensive to recover, and useful in a number of applications. In industry, calcium is used in the refining of metals like lead, aluminum, zirconium, and uranium. Calcium alloyed with iron in steel production reduces surface defects. When alloyed with lead in the manufacture of maintenance-free automobile batteries, it increases battery life. The metal is also used to produce vitamin B5, calcium pantothenate. 

The lithium is in the form of an alloy with magnesium or aluminium which retains much of the tritium until it is released by treatment with acid. Alternatively the tritium can be produced by neutron irradiation of enriched LiF at 450° in a vacuum and then recovered from the gaseous products by diffusion through a palladium barrier. As a result of the massive production of tritium for thermonuclear devices and research into energy production by fusion reactions, tritium is available cheaply on the megacurie scale for peaceful purposes. The most convenient way of storing the gas is to react it with finely divided uranium... 

For reactor fuel, the ternary uranium-plutonium-carbon monocarbide is prepared by reduction of (U, Pu)02 with graphite [FI], by melting a uranium-plutonium alloy with graphite, or by melting separately prepared individual carbides in an electric arc [K2]. Even though at low temperatures UC exists in the stoichiometric composition, the need for excess carbon for the... 

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. 

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