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Oriented Dioxide Films on Uranium

Description: This report deals with the formation of oriented layers of an oxide which form during oxidation without any evident relationship to the parent and underlying metal. It is offered without explanation or proposed mechanism.
Date: July 6, 1954
Creator: Waber, James T. & O'Rourke, J. A.
Partner: UNT Libraries Government Documents Department

Thermal Conductivity of UO2

Description: Report discussing the thermal conductivity of uranium dioxide. The first part of the report includes the thermal effects on the substance's physical form, while the second part describes the experimental details.
Date: September 1962
Creator: Daniel, J. L. 1924-; Matolich, J., Jr. & Deem, H. W.
Partner: UNT Libraries Government Documents Department


Description: A description of hot laboratory metallography and techniques of operation are presented. These facilities and techniques provided a means of examining fuel elements that contain UO/sub 2/ after irradiation to high burnups. Some unusual irradiation characteristics of UO/sub 2/ were observed, and each effect is discussed. A complete explanation of the causes of such effects has not yet been obtained. (auth)
Date: January 15, 1958
Creator: Barney, W.K. & Wemple, B.D.
Partner: UNT Libraries Government Documents Department


Description: An investigation of the causes of observed explosive reaction of zirconium-coated uranium dioxide on dissolution in nitric acid was conducted. It was concluded that such a reaction is to be expected. Possible but unconfirmed methods of alleviating the problem are suggested. (J.R.D.)
Date: June 11, 1957
Creator: Robinson, M.T.
Partner: UNT Libraries Government Documents Department

The Nitric Acid Leaching of Uranium Dioxide in a Recirculating Dissolver

Description: A brief study of the nitric acid leaching of sheared Zircaloy and stainless-steel-clad UO/sub 2/ fuels was carried out. The study was intended to demonstrate the leaching process and the use of a removable dissolver canister for transport and charge duty. In addition, the effect of sheared element length on leaching time cycles was studied. (L.T.W.)
Date: October 20, 1960
Creator: Smith, P. W.
Partner: UNT Libraries Government Documents Department


Description: Development of the boiling water UO/sub 2/ fueled Variable Moderator Reactor (VMR) is conducted under contract for the USAEC. The initiation and progress of work under Phase I of the contract, Physics and Kinetic Analysis and Initial Evaluation,'' and the preparation for Phase II, Critical Experiment and Analysis of Results,'' are reported. A hydrodynamic flow sheet representing the sequence of calculations for the BOCH program was prepared. A preliminary block diagram of the kinetics model of the VMR was prepared. Work is reported on the PUREE code which is designed to give an accurate representation of the physics of the VMR core. A fuel element fabrication speciftcation was prepared and released for quotations. A study was made to select the most appropriate material for void simulation throughout the range of interest in the VMR. (W.D.M.)
Date: August 31, 1959
Partner: UNT Libraries Government Documents Department


Description: ABS>A review of laboratory diffusion studies on uranium and its compounds and alloys is presented. Included are results and analysis of studies on diffusion in single-phase and in multiphase U alloys, diffusion of gases in U, and diffusion in UO/sub 2/. (J.R.D.)
Date: May 1, 1961
Creator: Rothman, S.J.
Partner: UNT Libraries Government Documents Department


Description: Urania rods 6-in. long and 0.475-in. in diameter were extruded and sintered to densities exceeding 94% of the theoratical urania density. The rods dropped freely through a straight metal tube 8-in. long with an internal diameter 0.004-in. greater than the diameter of the rods. All properties of the extruded and sintered rods relevant to their use as a nuclear fuel material were at least equal to the corresponding properties of pressed and sintered urania pellets. Extruded and sintered urania rods can be produced with standard ceramic-industry machinery. From preliminary estimates it appears that extrusions may be produced more cheaply than pellets. (auth)
Date: January 23, 1961
Partner: UNT Libraries Government Documents Department


Description: A survey was made of methods potentially useful for the determination of the oxygen to metal ratio in mixed oxides of uranium and plutonium. A gravimetric method was selected as being the most promising for adaptation in a short period of time. Development of the technique resulted in a reliable method which meets the requirements for unirradiated mixed oxide fuel samples. The method, based upon an equilibrium weight at 700 deg C in dry hydrogen, was shown to be capable of measurement of O/(Pu + U) ratios in 20% PuO/sub 2/--80% UO/sub 2/ pellets with a standard deviation of plus or minus 0.001. (auth)
Date: May 31, 1963
Creator: Lyon, W.L.
Partner: UNT Libraries Government Documents Department

Intergranular fracture in UO2: derivation of traction-separation law from atomistic simulations

Description: In this study, the intergranular fracture behavior of UO2 was studied by molecular dynamics simulations using the Basak potential. In addition, the constitutive traction-separation law was derived from atomistic data using the cohesive-zone model. In the simulations a bicrystal model with the (100) symmetric tilt E5 grain boundaries was utilized. Uniaxial tension along the grain boundary normal was applied to simulate Mode-I fracture. The fracture was observed to propagate along the grain boundary by micro-pore nucleation and coalescence, giving an overall intergranular fracture behavior. Phase transformations from the Fluorite to the Rutile and Scrutinyite phases were identified at the propagating crack tips. These new phases are metastable and they transformed back to the Fluorite phase at the wake of crack tips as the local stress concentration was relieved by complete cracking. Such transient behavior observed at atomistic scale was found to substantially increase the energy release rate for fracture. Insertion of Xe gas into the initial notch showed minor effect on the overall fracture behavior.
Date: October 1, 2013
Creator: Zhang, Yongfeng; Millett, Paul C; Tonks, Michael R; Bai, Xian-Ming & Biner, S Bulent
Partner: UNT Libraries Government Documents Department

X-Ray Absorption Spectroscopy of Uranium Dioxide

Description: After the CMMD Seminar by Sung Woo Yu on the subject of the x-ray spectroscopy of UO2, there arose some questions concerning the XAS of UO2. These questions can be distilled down to these three issues: (1) The validity of the data; (2) The monchromator energy calibration; and (3) The validity of XAS component of the figure shown. The following will be shown: (1) The data is valid; (2) It is possible to calibrate the monchromator; and (3) The XAS component of the above picture is correct. The remainder of this document is in three sections, corresponding to these three issues.
Date: December 10, 2010
Creator: Tobin, J G
Partner: UNT Libraries Government Documents Department

Stress-induced phase transformation in nanocrystalline UO2

Description: We report a stress-induced phase transfonnation in stoichiometric UO{sub 2} from fluorite to the {alpha}-PbO{sub 2} structure using molecular dynamics (MD) simulations and density functional theory (DFT) calculations. MD simulations, performed on nanocrystalline microstructure under constant-stress tensile loading conditions, reveal a heterogeneous nucleation of the {alpha}-PbO{sub 2} phase at the grain boundaries followed by the growth of this phase towards the interior of the grain. The DFT calculations confinn the existence of the {alpha}-PbO{sub 2} structure, showing that it is energetically favored under tensile loading conditions.
Date: January 1, 2009
Creator: Uberuaga, Blas Pedro & Desai, Tapan
Partner: UNT Libraries Government Documents Department

Fabrication by BelgoNucleiare of plutonium fuel rods for the SNR reactor

Description: From symposium on fuel and elements for fast reactors; Brussels, Belgium (2 Jul 1973). After having summarized the basic specifications of fuel rods for the first SNR core, this document briefly describes the fabrication process that will be used, sets out certain problems linked with the industrial operation of a plutonium fuel production unit, and comments on some fabrication stages of particular importance as regards obtaining the characteristics desired for the fuels. The facilities in which the fuel will be fabricated are briefly described. (auth)
Date: January 1, 1973
Creator: Leblanc, J.M.
Partner: UNT Libraries Government Documents Department


Description: Research on a welding process for closing the ends of pathfinder fuel elements is reported. Optimum parameters for certain variables (amperage, weld travel, preheat, etc.) affecting weld quality were determined, and two modified end cap designs were investigated and found to reduce weld sensitivity to certain variables. Use of chills on the fuel tube greatly improved weld puddie geometry and microstructure. Optimum weld parameters for rods containing UO/sub 2/ fuel were experimentally established. (D.C.W.)
Date: July 30, 1963
Creator: Boschke, R.A. & Wiggins, R.J.
Partner: UNT Libraries Government Documents Department


Description: An occurrence at the SRE which caused approximately 7 fuel elements to part when being pulled from the reactor complicated reprocessing, however the bulk of the elements may still be reprocessed as planned. New or reworked pants for the mechanical decladder were supplied by the fabricators for rebuilding in ORNL shops. Administrative actions dictated by budgetary considerations include reduction of UO/sub 2/ pellet order to the quantity needed this fiscal year, reduction of Mark III prototype fuel element to 12, stoppage of all work by REE Division personnel, and stoppage of all work not related to SRE fuel element reprocessing. (auth)
Date: September 1, 1959
Creator: Klima, B.B.
Partner: UNT Libraries Government Documents Department