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High-temperature annealing of natural UO{sub 2+x}

Description: Four powdered samples of natural UO{sub 2+x} (uraninite) were annealed in a reducing atmosphere up to 1200 C. Initial unit cell parameters ranged from a{sub o}=0.5463 to 0.5385 nm. Small amounts of UO{sub 2.25} occur in all samples after annealing. Annealing curves show effects of recovery of point defects in the oxygen sublattice, ordering of U{sup 4+} and U{sup 6+}, vacancy migration in the cation sublattice, and second order phase transformations. Difference in annealing behavior of UO{sub 2+x} with x<0.15 as compared to x=0.25 between 400 and 700 C is due to ordering of U{sup 4+} and U{sup 6+}. Density increased after annealing except for one sample in which a large number of cavities (1-2{mu}m) formed. Oxidation and chemical composition have a more dramatic effect on the structural state of natural UO{sub 2+x} than self-irradiation caused by {alpha}-decay damage.
Date: December 31, 1990
Creator: Janeczek, J. & Ewing, R.C.
Partner: UNT Libraries Government Documents Department


Description: A detailed description of the processing of pitchblende ores used at the Port Hope, Canada, refinery is given including both the recovery and purification of U and Fu. The health hazards present in the processing are discussed, and recommendations are made which will insure adequate health protection. (L.T.W.)
Date: February 26, 1945
Creator: Anonsen, S.H.
Partner: UNT Libraries Government Documents Department

U-Sries Disequilibra in Soils, Pena Blanca Natural Analog, Chihuahua, Mexico

Description: The Nopal I uranium deposit located in the Sierra Pena Blanca, Mexico. The deposit was mined in the early 1980s, and ore was stockpiled close by. This stockpile area was cleared and is now referred to as the Prior High Grade Stockpile (PHGS). Some of the high-grade boulders from the site rolled downhill when it was cleared in the 1990s. For this study soil samples were collected from the alluvium surrounding and underlying one of these boulders. A bulk sample of the boulder was also collected. Because the Prior High Grade Stockpile had no ore prior to the 1980s a maximum residence time for the boulder is about 25 years, this also means that the soil was at background as well. The purpose of this study is to characterize the transport of uranium series radionuclides from ore to the soil. Transport is characterized by determining the activities of individual radionuclides and daughter to parent ratios. Isotopes of the uranium series decay chain detected include {sup 210}Pb, {sup 234}U, {sup 230}Th, {sup 226}Ra, {sup 214}Pb, and {sup 214}Bi. Peak areas for each isotope are determined using gamma-ray spectroscopy with a Canberra Ge (Li) detector and GENIE 2000 software. The boulder sample is close to secular equilibrium when compared to the standard BL-5 (Beaver Lodge Uraninite from Canada). Results for the soils, however, indicate that some daughter/parent pairs are in secular disequilibrium. These daughter/parent (D/P) ratios include {sup 230}Th/{sup 234}U, which is greater than unity, {sup 226}Ra/{sup 230}Th, which is also greater than unity, and {sup 210}Pb/{sup 214}Bi, which is less than unity. The gamma-ray spectrum for organic material lacks {sup 230}Th peaks, but contains {sup 234}U and {sup 226}Ra, indicating that plants preferentially incorporate {sup 226}Ra. Our results, combined with previous studies require multistage history of mobilization of the uranium series ...
Date: March 16, 2006
Creator: French, D.; Anthony, E. & Goodell, P.
Partner: UNT Libraries Government Documents Department


Description: Three groups of experiments were carried out to determine ihe disiribuiion of Ra in HNO/sub 3/ digesiion of rich pitchblende ores. The various experimenis were designed to determine the effect of washing on the removal of Ra from the gangue, effect of excess HNO/sub 3/ and time of digestion on the removal of Ra from the ore, and effect of the concentration of HNO/sub 3/ on the extraction of Ra. (W.L.H.)
Date: October 31, 1958
Creator: Thomas, H.C.; Tomcufcik, A.S. & Miller, J.L.
Partner: UNT Libraries Government Documents Department


Description: U{sup 6+}-minerals commonly form during the alteration of uraninite and spent nuclear fuel under oxidizing conditions. By the incorporation of actinides and fissiogenic elements into their structures, U{sup 6+}-minerals may be important in retarding the migration of radionuclides released during corrosion of spent nuclear fuel. Thus, the stability and the structural transformation of the U{sup 6+}-minerals in radiation fields are of great interest.
Date: July 7, 2005
Creator: Utsunomiya, S. & Ewing, R.C.
Partner: UNT Libraries Government Documents Department


Description: Investigations on problems related to the use of MgX and other feed materials in the Plant 6 U refinery at St. Louis, Mo., have continued, with emphasis on the extraction of process feeds by neutral ether. Results of Scheibel column extraction tests wtth neutral ether on a variety of pitchblende, MgX, and V-20 soda salt feed materials indicate that the addition of Fe to complex interfering elements can reduce U losses in raffinates to lower levels than are attainable with acid ether in the absence of Fe. The beneficial effect of neutral ether on transfer of contaminants, especially Mo, to the ether extract was substantiated. It is indicated that the inclusion of V-20 soda salt in a feed tends to increase U losses in extraction; the addition of Fe was shown to be advantageous here also. Sources and costs of added Fe are considered. (G.Y.)
Date: June 30, 1951
Creator: Ewing, R.A.; Kiehl, S.J. Jr.; Sharpe, R.E. & Bearse, A.E.
Partner: UNT Libraries Government Documents Department

Composition, Reactivity, and Regulations of Extracellular Metal-Reducing Structures (Bacterial Nanowires) Produced by Dissimilatory Metal Reducing Bacteria

Description: This research proposal seeks to describe the composition and function of electrically conductive appendages known as bacterial nanowires. This project targets bacterial nanowires produced by dissimilatory metal reducing bacteria Shewanella and Geobacter. Specifically, this project will investigate the role of these structures in the reductive transformation of iron oxides as solid phase electron acceptors, as well as uranium as a dissolved electron acceptor that forms nanocrystalline particles of uraninite upon reduction.
Date: June 1, 2006
Creator: Scholten, Johannes
Partner: UNT Libraries Government Documents Department


Description: The formation of high sludge strength agglomerates is a key concern to the Sludge Treatment Project (STP) to ensure the sludge can be retrieved after planned storage for up to 10 years in Sludge Transport and Storage Containers (STSC) at T Plant. This report addresses observations of agglomerate formation, conditions that the data shows lead to agglomeration, the frequency of agglomerate formation and postulated physiochemical mechanisms that may lead to agglomeration. Although the exact underlying chemistry of K Basin sludge agglomerate formation is not known, the factors that lead to agglomeration formation, based on observations, are as follows: (1) High Total Uranium Content (i.e., sample homogeneity and influence from other constituents); (2) Distribution of Uranium Phases (i.e., extent of conversion from uraninite to uranium oxide hydroxide compounds); (3) Sample Dry-out (loss of cover water); (4) Elevated temperature; (5) Solubility ofU(IV) phases vs. U(VI) phases; and (6) Long storage times. Agglomerated sludge has occurred infrequently and has only been observed in four laboratory samples, five samples subjected to hydrothermal testing (performed for 7 to 10 hours at {approx}185 C and 225 psig), and indirectly during six sampling events in the KE Basin. In the four laboratory samples where agglomerates were observed, the agglomerates exhibited high shear strength and the sample container typically had to be broken to remove the solids. The total uranium content (dry basis) for the four samples (KE Pit, KC-2/3 SS, KC-2/3 M250 and 96-13) were {approx}8 wt%, {approx}59.0 wt%, 68.3 wt% and 82 wt%. The agglomerates that were present during the six sampling events were undoubtedly disturbed and easily broken apart during sample collection, thus no agglomerates were observed in subsequent laboratory analyses. The highest shear strengths measured for K Basin sludge samples were obtained after hydrothermal treatment (7 to 10 hr at 185 C) of high-uranium-content ...
Date: June 10, 2010
Creator: SR, HILL
Partner: UNT Libraries Government Documents Department