Uranium impurities

Uranium impurities in most natural solids generally occur in very low concentration. The density of tracks is, therefore, extremely low, usually too low to be measured. Thus, the fission track method is generally appli-... 

Minerals and rocks of similar composition but of different geographic or geologic origin generally include different relative amounts of thorium and uranium impurities after generally long periods of time they also include, therefore, different relative amounts of the isotopes of lead. The... 

In addition to the black spot contrast, most crystals of neutron-irradiated amethyst quartz showed black lines, which were subsequently identified as the tracks of particles produced by the fission of uranium impurity atoms (see Section 8.13.3),... 

The presence of uranium in a sample exposed to a flux of thermal neutrons can cause errors if the nuclide or nuclides determined are fission products or are isotopic with them. Hudgens and Dabagian (39) determined zirconium in zirconium-hafnium mixtures by separating the Nb , daughter of Zr formed by n,y reaction, after the addition of carrier. Contributions from fission product niobium (Nb ) can be allowed foi by irradiating a further sample, isolating fission product Ba ° and from the fission yield curve making allowance for radioactive niobium derived from any uranium impurity. 

Fig. 1.3 Setup for first chemical experiments with element 104 - now Rf Dubna, the mid-1960s [10]. The broken frames outline the placement of resistive heaters, paraffin and cadmium shielded the detectors from neutrons to prevent induced fission of uranium impurities in mica. Thermal decomposition of NaNbClg was the source of NbC E vapor. A Faraday cup was placed inside the target chamber (not shown).

Extraction of Bertrandite. Bertrandite-containing tuff from the Spor Mountain deposits is wet milled to provide a thixotropic, pumpable slurry of below 840 p.m (—20 mesh) particles. This slurry is leached with sulfuric acid at temperatures near the boiling point. The resulting beryUium sulfate [13510-49-1] solution is separated from unreacted soflds by countercurrent decantation thickener operations. The solution contains 0.4—0.7 g/L Be, 4.7 g/L Al, 3—5 g/L Mg, and 1.5 g/L Fe, plus minor impurities including uranium [7440-61-1/, rare earths, zirconium [7440-67-7] titanium [7440-32-6] and zinc [7440-66-6]. Water conservation practices are essential in semiarid Utah, so the wash water introduced in the countercurrent decantation separation of beryUium solutions from soflds is utilized in the wet milling operation. 

Action of chlorine on uranium oxide to recover volatile uranium chloride Removal of iron oxide impurity from titanium oxide by volatilization hy action of chlorine... 

The paper describes the different chemical sensors and mathematical methods applied and presents the review of electronic tongue application for quantitative analysis (heavy metals and other impurities in river water, uranium in former mines, metal impurities in exhaust gases, ets) and for classification and taste determination of some beverages (coffee, bear, juice, wines), vegetable oil, milk, etc. [1]. 

The compound MgGa204, when activated by divalent impurities such as Mn +, is used in ultraviolet-activated powders as a brilliant green phosphor. Another very important application is to improve the sensitivity of various bands used in the spectroscopic analysis of uranium. Minor uses are as high-temperature liquid seals, manometric fluids and heat-transfer media, and for low-temperature solders. 

For example, consider the chemical composition of a very old crystal of pitchblende, U308. We may presume that this crystal was formed at a time when chemical conditions for its formation were favorable. For example, it may have precipitated from molten rock during cooling. The resulting crystals tend to exclude impurities. Yet, careful analysis shows that every deposit of pitchblende contains a small amount of lead. This lead has accumulated in the crystal, beginning at the moment the pure crystal was formed, due to the radioactive decay of the uranium. 

Uranium is a heavy element that has a number of isotopes (see Textbox 16). Minerals and rocks as well as human made materials such as ceramics and glass often contain trace amounts of uranium as impurities. The most abundant isotope of this element, uranium-238, is radioactive and most of it decays into thorium-234 by the emission of alpha particles ... 

The four isotopes, as those of any element, have the same chemical properties. The four are not, however, uniformly distributed in the earth s crust the occurrence of three of them, in minerals and rocks, is associated with the radioactive decay of isotopes of thorium and uranium. In most minerals and rocks the relative amounts (or the isotopic ratios) of the isotopes of lead (often expressed relative to the amount of stable lead-204) are generally within well-known ranges, which are independent of the composition of the mineral or rock they are, however, directly related to the amounts of radioactive thorium and uranium isotope impurities in them. 

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