342 Matching Results

Search Results

Advanced search parameters have been applied.

REMOTE PLASTIC BAG PASSOUT UNIT FOR HIGH-LEVEL RADIOCHEMICAL OPERATIONS

Description: A system is designed for making remote sealed-bag passouts from a multicurie-level chemistry processing enclosure. The polyethylene bags are changed remotely without exposing contaminated surfaces while always maintaining a low leak rate seal. The system employs an interchange box (passout box) attached to the chemistry enclosure. Integrated with the box is a hydraulically operated jack that raises and lowers the bags, and a welder-cutter for sealing them. A single master-slave manipulator teamed with the above units handles all operations. (auth)
Date: August 1, 1961
Creator: Fleischer, E.S.; Parsons, T.C. & Howe, P.W.
Partner: UNT Libraries Government Documents Department

Multiple melting peak analysis with gel-spun ultra-high molar mass polyethylene

Description: The multiple melting peaks observed on differential scanning calorimetry (DSC) of ultrahigh molar-mass PE fibers are analyzed as a function of sample mass. Using modern DSC capable of recognizing single fibers of microgram size, it is shown that the multiple peaks are in part or completely due to sample packing. Loosely packed fibers fill the entire volume of the pan with rather large thermal resistance to heat flow. On melting, the fibers contract and flow to collect ultimately at the bottom of the pan. This process seems to be able to cause an artifact of multistage melting dependent on the properties of the fibers. A method is proposed to greatly reduce, or even eliminate, errors of this type. The crucial elements of the analysis of melting behavior and melting temperature are decreasing the sample size and packing the individual fibers in a proper geometry, or to introduce inert media to enhance heat transport.
Date: December 31, 1996
Creator: Boller, A. & Wunderlich, B.
Partner: UNT Libraries Government Documents Department

Study of low-lying resonant states in 16F using an 15O radioactiveion beam

Description: A 120 MeV {sup 15}O radioactive ion beam with an intensity on target of 4.5 x 10{sup 4} pps has been developed at the 88-inch cyclotron at the Lawrence Berkeley National Laboratory. This beam has been used to study the level structure of {sup 16}F at low energies via the p({sup 15}O,p) reaction using the thick target inverse kinematics method on a polyethylene target. The experimental excitation function was analyzed using R-matrix calculations. Significantly improved values for the level widths of the four low-lying states in 16F are reported. Good agreement with the theoretical spectroscopic factors is also obtained.
Date: January 22, 2007
Creator: Lee, D.W.; Perajarvi, K.; Powell, J.; O'Neil, J.P.; Moltz, D.M.; Goldberg, V.Z. et al.
Partner: UNT Libraries Government Documents Department

EFFECTS OF TRITIUM ON UHMW-PE, PTFE, AND VESPEL POLYIMIDE

Description: Samples of ultrahigh molecular weight polyethylene (UHMW-PE), polytetrafluoroethylene (PTFE), and the polyimide Vespel{reg_sign} were exposed to tritium gas in closed containers initially at 101 kPa (1 atmosphere) pressure and ambient temperature for various times up to 2.3 years. Tritium exposure effects on the samples were characterized by dynamic mechanical analysis (DMA) and radiolysis products were characterized by measuring the total final pressure and composition in the exposure containers at the end of exposure period.
Date: November 1, 2006
Creator: Clark, E & Kirk Shanahan, K
Partner: UNT Libraries Government Documents Department

Understanding High Voltage Vacuum Insulators for Microsecond Pulses

Description: High voltage insulation is one of the main areas of pulsed power research and development since the surface of an insulator exposed to vacuum can fail electrically at an applied field more than an order or magnitude below the bulk dielectric strength of the insulator. This is troublesome for applications where high voltage conditioning of the insulator and electrodes is not practical and where relatively long pulses, on the order of several microseconds, are required. Here we give a summary of our approach to modeling and simulation efforts and experimental investigations for understanding flashover mechanism. The computational work is comprised of both filed and particle-in-cell modeling with state-of-the-art commercial codes. Experiments were performed in using an available 100-kV, 10-{micro}s pulse generator and vacuum chamber. The initial experiments were done with polyethylene insulator material in the shape of a truncated cone cut at +45{sup o} angle between flat electrodes with a gap of 1.0 cm. The insulator was sized so there were no flashovers or breakdowns under nominal operating conditions. Insulator flashover or gap closure was induced by introducing a plasma source, a tuft of velvet, in proximity to the insulator or electrode.
Date: August 15, 2007
Creator: J.B., J; D.A., G; T.L., H; E.J., L; R.D., S; L.K., T et al.
Partner: UNT Libraries Government Documents Department

Evaluation of a novel UHMWPE bearing for applications in precision slideways

Description: This paper presents a novel slideway bearing design comprised of a thin-film (0.1 mm-0.2 mm) of ultra-high molecular weight polyethylene (UHMWPE) bound to a rigid hemispherical substrate. Two prototype bearing designs were fabricated and tested to characterize the coefficient of friction (dynamic and static) and wear of the polymer. In addition, similar bearings were incorporated into a kinematically constrained rectilinear carriage to determine the repeatability of motion during multiple traverses. The first bearing had a radius of curvature on the order of 2.38 mm incorporating an UHMWPE film thickness between 0.1 mm and 0.2 mm. The friction coefficient was measured to be between 0.155 and 0.189 for normal loads of 11.5 N and 2.2 N, respectively at a surface speed of 4.2 mm {center_dot} s{sup -1}. This bearing failed after a traverse of approximately 700 m at a load of 11.5 N. A similar evaluation procedure was carried out on a bearing of radius 6.35 mm resulting in a friction coefficient between 0.125 and 0.185 at loads of 27.8 N and 2.2 N, respectively, and the bearing endured a traverse of over 2.2 km at a load of approximately 28 N (in both air and vacuum conditions) with a surface speed of 4.2 mm {center_dot} s{sup -1}. The second bearing prototype was further subjected to a repeatability test. In this setup, a carriage incorporating five bearings was traversed in a nominally linear path while vertical deviations for multiple traverses were measured by a custom built displacement sensor. Deviations from a linear path were observed to repeat to within a few nanometers about nominal variations of less than 10 nm for a traverse distance of 10 mm. This system and other subsystems used to characterize the friction coefficient and noise of the polymer bearing are presented.
Date: March 8, 2005
Creator: Buice, E S; Yang, H; Smith, S T; Hocken, R J & Seugling, R M
Partner: UNT Libraries Government Documents Department

Structure and Evolution of Ordered Domains in Deeply Quenched Polyrthelene Melt

Description: Solidification of polymeric materials, a complex process in which the entangled polymer melt becomes a composite of amorphous and crystalline domains, strongly depends on how the melt is cooled below its crystallization temperature. If cooling is at moderate rates, the most common and well. understood mechanism is via nucleation and growth of spherulites, but special cases exist where crystallization is preceded by a pre pre-transition state induced by density fluctuations. Such multi-step crystallization scenarios are suggested by many experiments, and recent theoretical and simulation work. Via energetic and geometric analyses, we have examined the structure of mesomorphic domains and the dynamics of their formation and evolution, including atomic scale details of molecular addition to ordered domains, as well as particle dynamics in the system, including high mobility jumps in the ordered domains at wavelengths matching the monomer spacing.
Date: April 25, 2007
Creator: Lacevic, N; Fried, L & Gee, R
Partner: UNT Libraries Government Documents Department

SiO2 - polyethylene reflected critical assembly

Description: The Planet universal critical assembly machine was used to perform a series of three critical experiments. This experiment used HEU foils reflected by polyethylene and interleaved with plates of SiO{sub 2} glass and polyethylene. Only the experiment performed using the SiO{sub 2} matrix material is evaluated in this report. The assembly was delayed critical with 33 HEU foils or 17 units (sets of HEU foils). The critical assembly has an intermediate neutron spectrum, with 51.2% of the fissions occurring between 0.625 eV and 100 keV. The calculational results show good agreement with the experimental results.
Date: January 1, 2001
Creator: Brewer, R. W. (Roger W.) & Sanchez, R. G. (Rene G.)
Partner: UNT Libraries Government Documents Department

Development of a Remote External Repair Tool for Damaged or Defective Polyethylene Pipe

Description: Current procedures for repairing polyethylene (PE) gas pipe require excavation, isolation, and removal of the damaged section of pipe followed by fusing a new section of pipe into place. These techniques are costly and very disruptive. An alternative repair method was developed at Timberline Tool with support from Oregon State University (OSU) and funding by the U. S. Department of Energy National Energy Technology Laboratory (DOE/NETL). This project was undertaken to design, develop and test a tool and method for repairing damaged PE pipe remotely and externally in situ without squeezing off the flow of gas, eliminating the need for large-scale excavations. Through an iterative design and development approach, a final engineered prototype was developed that utilizes a unique thermo-chemical and mechanical process to apply a permanent external patch to repair small nicks, gouges and punctures under line pressure. The project identified several technical challenges during the design and development process. The repair tool must be capable of being installed under live conditions and operate in an 18-inch keyhole. This would eliminate the need for extensive excavations thus reducing the cost of the repair. Initially, the tool must be able to control the leak by encapsulating the pipe and apply slight pressure at the site of damage. Finally, the repair method must be permanent at typical operating pressures. The overall results of the project have established a permanent external repair method for use on damaged PE gas pipe in a safe and cost-effective manner. The engineered prototype was subjected to comprehensive testing and evaluation to validate the performance. Using the new repair tool, samples of 4-inch PE pipe with simulated damage were successfully repaired under line pressure to the satisfaction of DOE/NETL and the following natural gas companies: Northwest Natural; Sempra Energy, Southwest Gas Corporation, Questar, and Nicor. However, initial ...
Date: June 30, 2006
Creator: Green, Kenneth H.; Rochefort, Willie E.; Wannenmacher, Nick; Clark, John A. & Harris, Kevin
Partner: UNT Libraries Government Documents Department

PORTSMOUTH ON-SITE DISPOSAL CELL HIGH DENSITY POLYETHYLENE GEOMEMBRANE LONGEVITY

Description: It is anticipated that high density polyethylene (HDPE) geomembranes will be utilized within the liner and closure cap of the proposed On-Site Disposal Cell (OSDC) at the Portsmouth Gaseous Diffusion Plant. The likely longevity (i.e. service life) of HDPE geomembranes in OSDC service is evaluated within the following sections of this report: (1) Section 2.0 provides an overview of HDPE geomembranes, (2) Section 3.0 outlines potential HDPE geomembranes degradation mechanisms, (3) Section 4.0 evaluates the applicability of HDPE geomembrane degradation mechanisms to the Portsmouth OSDC, (4) Section 5.0 provides a discussion of the current state of knowledge relative to the longevity (service life) of HDPE geomembranes, including the relation of this knowledge to the Portsmouth OSDC, and (5) Section 6.0 provides summary and conclusions relative to the anticipated service life of HDPE geomembranes in OSDC service. Based upon this evaluation it is anticipated that the service life of HDPE geomembranes in OSDC service would be significantly greater than the 200 year service life assumed for the OSDC closure cap and liner HDPE geomembranes. That is, a 200 year OSDC HDPE geomembrane service life is considered a conservative assumption.
Date: January 31, 2012
Creator: Phifer, M.
Partner: UNT Libraries Government Documents Department

MEASUREMENT OF AVERAGE NEUTRON ENERGIES FOR ($alpha$,n) NEUTRON SOURCES

Description: A method is presented for measuring the average energy of the neutrons from a source. The attenuation of the neutrons by polyethylene is measured by the use of a long counter in good geometry. The attenuation length is a sensitive function of the neutron energy. The average neutron energies from several ( alpha ,n) sources were measwed and agree well with values obtained by other techniques. (auth)
Date: April 1, 1959
Creator: Hess, W.N. & Smith, A.R.
Partner: UNT Libraries Government Documents Department

Relative Biological Effectiveness of HZE Fe Ions for Induction of Micro-Nuclei at Low Doses

Description: Dose-response curves for induction of micro-nuclei (MN) was measured in Chinese hamster V79 and xrs6 (Ku80-) cells and in human mammary epithelial MCF10A cells in the dose range of 0.05-1 Gy. The Chinese Hamster cells were exposed to 1 GeV/u Fe ions, 600 MeV/u Fe ions, and 300 MeV/u Fe ions (LETs of 151, 176 and 235 keV/{micro}m respectively) as well as with 320 kVp X-rays as reference. Second-order polynomials were fitted to the induction curves and the initial slopes (the alpha values) were used to calculate RBE. For the repair proficient V79 cells the RBE at these low doses increased with LET. The values obtained were 3.1 (LET=151 keV/{micro}m), 4.3 (LET = 176 keV/{micro}m) and 5.7 (LET = 235 keV/{micro}m), while the RBE was close to 1 for the repair deficient xrs6 cells regardless of LET. For the MCF10A cells the RBE was determined for 1 GeV/u Fe ions and found to be 5.4, slightly higher than for V79 cells. To test the effect of shielding, the 1 GeV/u Fe ion beam was intercepted by various thickness of high-density polyethylene plastic absorbers, which resulted in energy loss and fragmentation. It was found that the MN yield for V79 cells placed behind the absorbers decreased in proportion to the decrease in dose both before and after the Fe ion Bragg peak (excluding the area around the Fe-ion Bragg peak itself), indicating that RBE did not change significantly due to shielding. At the Bragg peak the effectiveness for MN formation per unit dose was decreased, indicating an 'overkill' effect by low-energy very high-LET Fe ions.
Date: January 16, 2007
Creator: Groesser, Torsten; Chun, Eugene & Rydberg, Bjorn
Partner: UNT Libraries Government Documents Department

Void morphology in polyethylene/carbon black composites

Description: A combination of small angle neutron scattering (SANS) and contrast matching techniques is used to determine the size and quantity of voids incorporated during fabrication of polyethylene/carbon black composites. The analysis used to extract void morphology from SANS data is based on the three-phase model of microcrack determination via small angle x-rayscattering (SAXS) developed by W.Wu{sup 12} and applied to particulate reinforced composites.
Date: December 31, 1996
Creator: Marr, D.W.M.; Wartenberg, M. & Schwartz, K.B.
Partner: UNT Libraries Government Documents Department

Shielding materials for high-energy neutrons

Description: The authors used the Monte Carlo transport code Los Alamos High-Energy Transport (LAHET) to study the shielding effectiveness of common shielding materials for high-energy neutrons. The source neutron spectrum was from the interaction of an 800-MeV proton beam and iron target. In a normal incident, the neutrons collided with walls made of six common shielding materials: water, concrete, iron, lead, polyethylene, and soil. The walls were of four different thicknesses: 25, 50, 75 and 100 cm. They then tallied the neutron spectra on the other side of the shielding wall and calculated the neutron doses. For the high-Z materials--iron and lead--they find that many neutrons with energies between 1--10 MeV are created when high-energy neutrons interact with shielding materials. For materials containing low-Z elements--water, soil, concrete, and polyethylene--the spectra show higher energy peaks at about 100 MeV. The studies show that for a given wall thickness, concrete is more effective than the other materials. They also studied the effectiveness of combinations of materials, such as concrete and water, concrete and soil, iron and polyethylene, or iron polyethylene and concrete.
Date: May 1, 1997
Creator: Hsu, H.H.
Partner: UNT Libraries Government Documents Department

Melting by temperature-modulated calorimetry

Description: Well-crystallized macromolecules melt irreversibly due to the need of molecular nucleation, while small molecules melt reversibly as long as crystal nuclei are present to assist crystallization. Furthermore, imperfect crystals of low-molar-mass polymers may have a sufficiently small region of metastability between crystallization and melting to show a reversing heat-flow component due to melting of poor crystals followed by crystallization of imperfect crystals which have insufficient time to perfect before the modulation switches to heating and melts the imperfect crystals. Many metals, in turn. melt sharply and reversibly as long as nuclei remain after melting for subsequent crystallization during the cooling cycle. Their analysis is complicated, however, due to thermal conductivity limitations of the calorimeters. Polymers of sufficiently high molar mass, finally, show a small amount of reversible. local melting that may be linked to partial melting of individual molecules. Experiments by temperature-modulated calorimetry and model calculations are presented. The samples measured included poly(ethylene terephthalate)s, poly(ethylene oxide)s, and indium. Two unsolved problems that arose from this research involve the origin of a high, seemingly stable, reversible heat capacity of polymers in the melting region, and a smoothing of melting and crystallization into a close-to-elliptical Lissajous figure in a heat-flow versus sample-temperature plot.
Date: September 1, 1997
Creator: Wunderlich, B.; Okazaki, Iwao; Ishikiriyama, Kazuhiko & Boller, A.
Partner: UNT Libraries Government Documents Department

Innovative Composites Through Reinforcement Morphology Design - a Bone-Shaped-Short-Fiber Composite

Description: This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The objective of this project is to improve the strength and toughness of conventional short-fiber composites by using innovative bone-shaped-short (BSS) fibers as reinforcement. We fabricated a model polyethylene BSS fiber-reinforced polyester-matrix composite to prove that fiber morphology, instead of interfacial strength, solves the problem. Experimental tensile and fracture toughness test results show that BSS fibers can bridge matrix cracks more effectively, and consume many times more energy when pulled out, than conventional-straight-short (CSS) fibers. This leads to both higher strength and fracture toughness for the BSS-fiber composites. A computational model was developed to simulate crack propagation in both BSS- and CSS-fiber composites, accounting for stress concentrations, interface debonding, and fiber pullout. Model predictions were validated by experimental results and will be useful in optimizing BSS-fiber morphology and other material system parameters.
Date: June 29, 1999
Creator: Zhu, Y.T.; Valdez, J.A.; Beyerlain, I.J.; Stout, M.G.; Zhou, S.; Shi, N. et al.
Partner: UNT Libraries Government Documents Department

A Simple, Inexpensive in Situ Method for Assessing Acute Toxicity of Effluents to Fish

Description: Test chambers for conducting in situ fish bioassays were constructed from 8L polyethylene bottles. Yearling fathead minnows (Pimephales promelas) and young-of-the-year bluegill (Lepomis macrochirus) demonstrated greater than 50 percent survival in the chambers after 65 days of exposure in a reservoir, river, and creek. Fathead minnow survival was substantially greater than that of bluegills. The chambers provide a simple, inexpensive, sensitive technique to screen effluents for toxicity.
Date: May 29, 2001
Creator: Wilde, E.W.
Partner: UNT Libraries Government Documents Department

FUELS IN SOIL TEST KIT: FIELD USE OF DIESEL DOG SOIL TEST KITS

Description: Western Research Institute (WRI) is commercializing Diesel Dog Portable Soil Test Kits for performing analysis of fuel-contaminated soils in the field. The technology consists of a method developed by WRI (U.S. Patents 5,561,065 and 5,976,883) and hardware developed by WRI that allows the method to be performed in the field (patent pending). The method is very simple and does not require the use of highly toxic reagents. The aromatic components in a soil extract are measured by absorption at 254 nm with a field-portable photometer. WRI added significant value to the technology by taking the method through the American Society for Testing and Materials (ASTM) approval and validation processes. The method is designated ASTM Method D-5831-96, Standard Test Method for Screening Fuels in Soils. This ASTM designation allows the method to be used for federal compliance activities. In FY 99, twenty-five preproduction kits were successfully constructed in cooperation with CF Electronics, Inc., of Laramie, Wyoming. The kit components work well and the kits are fully operational. In the calendar year 2000, kits were provided to the following entities who agreed to participate as FY 99 and FY 00 JSR (Jointly Sponsored Research) cosponsors and use the kits as opportunities arose for field site work: Wyoming Department of Environmental Quality (DEQ) (3 units), F.E. Warren Air Force Base, Gradient Corporation, The Johnson Company (2 units), IT Corporation (2 units), TRC Environmental Corporation, Stone Environmental, ENSR, Action Environmental, Laco Associates, Barenco, Brown and Caldwell, Dames and Moore Lebron LLP, Phillips Petroleum, GeoSyntek, and the State of New Mexico. By early 2001, ten kits had been returned to WRI following the six-month evaluation period. On return, the components of all ten kits were fully functional. The kits were upgraded with circuit modifications, new polyethylene foam inserts, and updated instruction manuals.
Date: May 31, 2001
Partner: UNT Libraries Government Documents Department