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319,268 Matching Results
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Modeling the post-yield flow behavior after neutron and electron irradiation of steels and iron-base alloys.
Irradiation hardening is an issue of practical importance as it relates to the remanent life and the nature of failure of reactor components exposed to displacement-producing radiation. For example, irradiation-induced yield strength increases in pressure vessel steels are directly related to increases in the ductile-to-brittle-transition-temperature of these materials. Other issues associated with hardening, such as reductions in ductility, toughness and fatigue life of structural steels are also of concern. Understanding these phenomena requires studies of fundamental microstructural mechanisms of hardening. Because of the limited supply of neutron-irradiated surveillance material, difficulties posed by the radioactivity of neutron-exposed samples and the uncertainty of irradiation conditions in this case, fundamental studies are often conducted using well-controlled experiments involving irradiation by electrons instead of neutrons. Also, in such studies, simple model alloys are used in place of steels to focus on the influence of specific alloy constituents. It is, therefore, important to understand the relationship between the results of this kind of experiment and the effects of in-reactor neutron exposure in order to use them to make predictions of significance to reactor component life. In this paper, we analyze the tensile behavior of pressure vessel steels (A212B and A350) irradiated by neutrons and electrons. …
Date:
January 13, 1999
Creator:
Dimelfi, R. J.
Object Type:
Article
System:
The UNT Digital Library
Bond Strength of Cementitious Borehole Plugs in Welded Tuff
Axial loads on plugs or seals in an underground repository due to gas, water pressures and temperature changes induced subsequent to waste and plug emplacement lead to shear stresses at the plug/rock contact. Therefore, the bond between the plug and rock is a critical element for the design and effectiveness of plugs in boreholes, shafts or tunnels. This study includes a systematic investigation of the bond strength of cementitious borehole plugs in welded tuff. Analytical and numerical analysis of borehole plug-rock stress transfer mechanics is performed. The interface strength and deformation are studied as a function of Young`s modulus ratio of plug and rock, plug length and rock cylinder outside-to-inside radius ratio. The tensile stresses in and near an axially loaded plug are analyzed. The frictional interface strength of an axially loaded borehole plug, the effect of axial stress and lateral external stress, and thermal effects are also analyzed. Implications for plug design are discussed. The main conclusion is a strong recommendation to design friction plugs in shafts, drifts, tunnels or boreholes with a minimum length to diameter ratio of four. Such a geometrical design will reduce tensile stresses in the plug and in the host rock to a level …
Date:
February 1, 1991
Creator:
Akgun, H. & Daemen, J. J. K.
Object Type:
Report
System:
The UNT Digital Library
Vapor space characterization of waste Tank 241-TY-101: Results from samples collected on 4/6/95
This report describes inorganic and organic analyses results from samples obtained from the headspace of the Hanford waste storage Tank 241-TY-101 (referred to as Tank TY-101). The results described here were obtained to support safety and toxicological evaluations. A summary of the results for inorganic and organic analytes is listed in Table 1. Detailed descriptions of the results appear in the text. Quantitative results were obtained for the inorganic compounds ammonia (NH{sub 3}), nitrogen dioxide (NO{sub 2}), nitric oxide (NO), and water vapor (H{sub 2}O). Sampling for hydrogen cyanide (HCN) and sulfur oxides (SO{sub x}) was not requested. In addition, quantitative results were obtained for the 39 TO-14 compounds plus an additional 14 analytes. Off these, 5 were observed above the 5-ppbv reporting cutoff. One tentatively identified compound (TIC) was observed above the reporting cutoff of (ca.) 10 ppbv and are reported with concentrations that are semiquantitative estimates based on internal-standard response factors. The six organic analyses identified are listed in Table 1 and account for approximately 100% of the total organic components in Tank TY-101. Two permanent gases, carbon dioxide (CO{sub 2}) and nitrous oxide (N{sub 2}O), were also detected. Tank TY-101 is on the Ferrocyanide Watch List.
Date:
November 1, 1995
Creator:
Klinger, G. S.; Clauss, T. W.; Ligotke, M. W.; Pool, K. H.; McVeety, B. D.; Olsen, K. B. et al.
Object Type:
Report
System:
The UNT Digital Library
Progress and future plans for MPC and A at Chelyabinsk-70
This paper describes that portion of the Nuclear Materials Protection, Control, and Accounting (MPC and A) program that is directed specifically to the needs of the All Russian Scientific Research Institute of Technical Physics (VNIITF), also called Chelyabinsk-70. Chelyabinsk-70 is located in the Ural Mountains, approximately 2000 km east of Moscow and 100 km south of Ekaterinburg. The MPC and A work that has been completed, is underway and planned at the facility will be described. During the first two years of the VNIITF project, emphasis was on the Pulse Research Reactor Facility (PRR), which contains one metal and two liquid pulse reactors and associated nuclear material storage rooms and a control center. A commissioning of the PRR was held in May of 1998. With the completion of the MPC and A work in the PRR, new physical protection work is focusing on other areas. VNIITF-wide physical protection initiatives underway include access control and computerized badging systems, and a central MPC and A control system. Measured physical inventory taking is a high priority for the VNIITF Project Team. A VNIITF-wide computerized accounting system is also being developed for the large and diverse inventory of nuclear material subject to MPC and …
Date:
July 8, 1999
Creator:
Apt, K.; Blasy, J.; Bukin, D.; Cahalane, P.; Churikov, Y.; Curtis, D. et al.
Object Type:
Article
System:
The UNT Digital Library
Microbial effects on colloidal agglomeration
Colloidal particles are known to enhance the transport of radioactive metals through soil and rock systems. This study was performed to determine if a soil microorganism, isolated from the surface samples collected at Yucca Mountain, NV, could affect the colloidal properties of day particles. The agglomeration of a Wyoming bentonite clay in a sterile uninoculated microbial growth medium was compared to the agglomeration in the medium inoculated with a Pseudomonas sp. In a second experiment, microorganisms were cultured in the succinate medium for 50 h and removed by centrifugation. The agglomeration of the clay in this spent was compared to sterile uninoculated medium. In both experiments, the agglomeration of the clay was greater than that of the sterile, uninoculated control. Based on these results, which indicate that this microorganism enhanced the agglomeration of the bentonite clay, it is possible to say that in the presence of microorganisms colloidal movement through a rock matrix could be reduced because of an overall increase in the size of colloidal particle agglomerates. 32 refs.
Date:
November 1, 1995
Creator:
Hersman, L.
Object Type:
Report
System:
The UNT Digital Library
Preparation of multilayered materials in cross-section for in situ TEM tensile deformation studies
The success of in-situ transmission electron microscopy experimentation is often dictated by proper specimen preparation. We report here a novel technique permitting the production of cross-sectioned tensile specimens of multilayered films for in-situ deformation studies. Of primary importance in the development of this technique is the production of an electron transparent micro-gauge section using focused ion beam technology. This microgauge section predetermines the position at which plastic deformation is initiated; crack nucleation, growth and failure are then subsequently observed.
Date:
May 13, 1997
Creator:
Wall, M. A.
Object Type:
Article
System:
The UNT Digital Library
Nuclear Regulatory Commission Issuances. Volume 42, No. 1, Pages 1--45
This report includes the issuances received during the specified period from the Commission (CLI), the Atomic safety and Licensing Boards (LBP), the Administrative Law Judges (ALJ), the Directors` Decisions (DD), and the Decisions on Petitions for Rulemaking (DPRM).
Date:
July 1, 1995
Creator:
unknown
Object Type:
Report
System:
The UNT Digital Library
Technology Base Studies of Long-Term MCFC Performance
Cathode dissolution into the electrolyte matrix and endurance of current collector/separator plate materials are the main life-limiting factors of the state-of-the art MCFC. These components are also major contributors to the total system cost. Therefore, to reduce capital cost, it is necessary to minimize hardware corrosion and increase cell life. This study consists of experimental evaluation of corrosion processes with the objective to further practical; understanding of corrosion behavior of alloys and alloy components under cathodic gas conditions. Nickel, iron, cobalt and stainless steels 310 and 316L are analyzed. The experimental study consists of: (1) Observation of open circuit potential (OCP) changes. Surface reactions occurring without net passage of current are proposed based on this measurement. (2) Applying cyclic voltammetry, which provides information about the possible electrode reactions at different stages of polarization. (3) Applying AC impedance to support the result of tasks 1 and 2 at different stages of oxidation, and data analysis by means of equivalent circuits. Open circuit conditions as well as positive and negative polarization are used in the impedance measurements. (4) Surface analysis of the electrodes by SEM-EDX and X-ray diffraction. To obtain more information from electrochemical measurements a novel approach has been applied in …
Date:
December 1, 1995
Creator:
Selman, J.R. & Yazici, M.S.
Object Type:
Article
System:
The UNT Digital Library
A study of turbulence in an evolving stable atmospheric boundary layer using large-eddy simulation
A study is made of the effects of stable stratification on the fine-scale features of the flow in an evolving stable boundary layer (SBL). Large-eddy simulation (LES) techniques are used so that spatially and temporally varying and intermittent features of the turbulence can be resolved; traditional Reynolds-averaging approaches are not well suited to this. The LES model employs a subgrid turbulence model that allows upscale energy transfer (backscatter) and incorporates the effects of buoyancy. The afternoon, evening transition, and nighttime periods are simulated. Highly anisotropic turbulence is found in the developed SBL, with occasional periods of enhanced turbulence. Energy backscatter occurs in a fashion similar to that found in DNS, and is an important capability in LES of the SBL. Coherent structures are dominant in the SBL, as the damping of turbulent energy occurs more at the smaller, less organized scales.
Date:
May 1, 1999
Creator:
Cederwall, R & Street, R L
Object Type:
Article
System:
The UNT Digital Library
Triaxial- and uniaxial-compression testing methods developed for extraction of pore water from unsaturated tuff, Yucca Mountain, Nevada
To support the study of hydrologic system in the unsaturated zone at Yucca Mountain, Nevada, two extraction methods were examined to obtain representative, uncontaminated pore-water samples from unsaturated tuff. Results indicate that triaxial compression, which uses a standard cell, can remove pore water from nonwelded tuff that has an initial moisture content greater than 11% by weight; uniaxial compression, which uses a specifically fabricated cell, can extract pore water from nonwelded tuff that has an initial moisture content greater than 8% and from welded tuff that has an initial moisture content greater than 6.5%. For the ambient moisture conditions of Yucca Mountain tuffs, uniaxial compression is the most efficient method of pore-water extraction. 12 refs., 7 figs., 2 tabs.
Date:
1989
Creator:
Mower, T. E.; Higgins, J. D. & Yang, I. C.
Object Type:
Article
System:
The UNT Digital Library
An update on projection methods for transient incompressible viscous flow
Introduced in 1990 was the biharmonic equation (for the pressure) and the concomitant biharmonic miracle when transient incompressible viscous flow is solved approximately by a projection method. Herein is introduced the biharmonic catastrophe that sometimes occurs with these same projection methods.
Date:
July 1, 1995
Creator:
Gresho, P.M. & Chan, S.T.
Object Type:
Article
System:
The UNT Digital Library
A novel condenser for EUV lithography ring-field projection optics
A condenser for a ring-field extreme ultra-violet (EUV) projection lithography camera is presented. The condenser consists of a gently undulating mirror, that we refer to as a ripple plate, and which is illuminated by a collimated beam at grazing incidence. The light is incident along the ripples rather than across them, so that the incident beam is reflected onto a cone and subsequently focused on to the arc of the ring field. A quasistationary illumination is achieved, since any one field point receives light from points on the ripples, which are distributed throughout the condenser pupil. The design concept can easily be applied to illuminate projection cameras with various ring-field and numerical aperture specifications. Ray-tracing results are presented of a condenser for a 0.25 NA EUV projection camera.
Date:
July 15, 1999
Creator:
Chapman, H. & Nugent, K. A.
Object Type:
Article
System:
The UNT Digital Library
Neutron spectroscopy of high-density amorphous ice.
Vibrational spectra of high-density amorphous ice (hda-ice) for H{sub 2}O and D{sub 2}O samples were measured by inelastic neutron scattering. The measured spectra of hda-ice are closer to those for high-pressure phase ice-VI, but not for low-density ice-Ih. This result suggests that similar to ice-VI the structure of hda-ice should consist of two interpenetrating hydrogen-bonded networks having no hydrogen bonds between themselves.
Date:
July 17, 1998
Creator:
Kolesnikov, A. I.
Object Type:
Article
System:
The UNT Digital Library
Production of heavy quark states at CDF
In this paper the author presents results on quarkonia production, B-meson production and b{bar b} correlations in p{bar p} collisions at {radical}s = 1.8 TeV. These results were obtained from data taken with the CDF detector at Fermilab. The author covers recently completed analyses of the 1992-95 collider run. Prospects for the near and more distant future are also discussed.
Date:
July 1, 1995
Creator:
Papadimitriou, V.
Object Type:
Article
System:
The UNT Digital Library
Detection of explosive events by monitoring acoustically-induced geomagnetic perturbations
The Black Thunder Coal Mine (BTCM) near Gillette, Wyoming was used as a test bed to determine the feasibility of detecting explosion-induced geomagnetic disturbances with ground-based induction magnetometers. Two magnetic observatories were fielded at distances of 50 km and 64 km geomagnetically north from the northernmost edge of BTCM. Each observatory consisted of three separate but mutually orthogonal magnetometers, Global Positioning System (GPS) timing, battery and solar power, a data acquisition and storage system, and a three-axis seismometer. Explosions with yields of 1 to 3 kT of TNT equivalent occur approximately every three weeks at BTCM. We hypothesize that explosion-induced acoustic waves propagate upward and interact collisionally with the ionosphere to produce ionospheric electron density (and concomitant current density) perturbations which act as sources for geomagnetic disturbances. These disturbances propagate through an ionospheric Alfven waveguide that we postulate to be leaky (due to the imperfectly conducting lower ionospheric boundary). Consequently, wave energy may be observed on the ground. We observed transient pulses, known as Q-bursts, with pulse widths about 0.5 s and with spectral energy dominated by the Schumann resonances. These resonances appear to be excited in the earth-ionosphere cavity by Alfven solitons that may have been generated by the …
Date:
October 7, 1999
Creator:
Lewis, J P; Rock, D R; Shaeffer, D L & Warshaw, S I
Object Type:
Report
System:
The UNT Digital Library
Mechanisms, chemistry, and kinetics of anaerobic biodegradation of cis-dichloroethylene and vinyl chloride. 1998 annual progress report
'The objectives of this study are to: (1) determine the biochemical pathways for reductive dehalogenation of cis-1,2-dichloroethene (cDCE) and vinyl chloride (VC), including identification of the enzymes involved, (2) determine the chemical requirements, especially the type and quantity of electron donors needed by the microorganisms for reductive dehalogenation, and (3) evaluate the kinetics of the process with respect to the concentration of both the electron donors and the electron acceptors (cDCE and VC). Progress has been made under each of the three primary objectives. One manuscript related to the first objective has been published. Manuscripts related to the other two objectives have been submitted for publication. Findings related to the three objectives are summarized.'
Date:
June 1, 1998
Creator:
McCarty, P.L. & Spormann, A.M.
Object Type:
Report
System:
The UNT Digital Library
Plasma Rotation, Dynamo, and Nonlinear Coupling in the Reversed Field Pinch
Two important effects of MHD fluctuations in the RFP and tokamak are current generation (the dynamo effect) and mode locking. In the T1 and MST RFP experiments new results reveal the mode dynamics underlying these phenomena. In T1 the effect of specific magnetic Fourier modes on the current density profile is evident. In MST, the MHD dynamo term ({delta}v x {delta}B) is measured in the plasma edge, and found to account for the time dependence of the edge current throughout a sawtooth cycle. As edge resistivity is increased in T1 the fluctuation amplitude increases to maintain the dynamo-driven current, as expected from MHD computation. The modes responsible for the dynamo often lock to the local magnetic field error at the vertical cut in MST. The plasma rotation velocity has been measured with a fast Doppler spectrometer to a time resolution of 1 {mu}s. The plasma rotation and mode phase velocity are remarkably well-correlated, with both slowing, in the presence of an impulsive field error, in a 100 {mu}s timescale.
Date:
July 1, 1995
Creator:
Prager, S. C.; Almagri, A. F. & Cekic, M.
Object Type:
Article
System:
The UNT Digital Library
Decontamination of metals by melt refining/slagging. An annotated bibliography: Update on stainless steel and steel
The following presentation is an update to a previous annotation, i.e., WINCO-1138. The literature search and annotated review covers all metals used in the nuclear industries but the emphasis of this update is directed toward work performed on mild steels. As the number of nuclear installations undergoing decontamination and decommissioning (D&D) increases, current radioactive waste storage space is consumed and establishment of new waste storage areas becomes increasingly difficult, the problem of handling and storing radioactive scrap metal (RSM) gains increasing importance in the DOE Environmental Restoration and Waste Management Program. To alleviate present and future waste problems, Lockheed Idaho Technologies Co (LITCO) is managing a program for the recycling of RSM for beneficial use within the DOE complex. As part of that effort, Montana Tech has been awarded a contract to help optimize melting and refining technology for the recycling of stainless steel RSM. The scope of the Montana Tech program includes a literature survey, a decontaminating slag design study, small wide melting studies to determine optimum slag compositions for removal of radioactive contaminant surrogates, analysis of preferred melting techniques, and coordination of large scale melting demonstrations (100--2,000 lbs) to be conducted at selected facilities. The program will support …
Date:
January 1, 1995
Creator:
Worchester, S. A.; Twidwell, L. G.; Paolini, D. J.; Weldon, T. A. & Mizia, R. E.
Object Type:
Report
System:
The UNT Digital Library
Above and beyond basic public participation
This paper evolved out of a discussion about public participation as it is currently being brought to the fore-front of clean-up activities at hazardous waste sites. There exists much official and unofficial documentation pertaining to the need for public involvement. The purposes for public involvement efforts in Environmental Restoration are: to enable substantive input to the clean-up process; methods for establishing formal, and now informal, mechanisms for public input and awareness of on-going facility activities; and the opening of better channels for communication and conflict resolution between the public and the facility. This presentation will briefly outline the regulatory approach for public outreach because many of these terms are used with such frequency, their meanings tend to get forgotten or misconstrued. Then, the authors will critique the most common methods for conducting public involvement as attempted through advisory boards and public meetings. For illustrative purposes, they will be referring to the site they are most familiar with, which is Los Alamos National Laboratory (LANL).
Date:
July 1, 1995
Creator:
Mathai, L. P.; Lefkoff, M. S. & Kelly, E. J.
Object Type:
Article
System:
The UNT Digital Library
OUT Success Stories: Advanced Airfoils for Wind Turbines
New airfoils have substantially increased the aerodynamic efficiency of wind turbines. It is clear that these new airfoils substantially increased energy output from wind turbines. Virtually all new blades built in this country today use these advanced airfoil designs.
Date:
August 31, 2000
Creator:
Jones, J. & Green, B.
Object Type:
Book
System:
The UNT Digital Library
Procyon: 18-MJ, 2-{mu}s pulsed power system
The Procyon high explosive pulsed power (HEPP) system was designed to drive plasma z-pinch experiments that produce Megajoule soft x-ray pulses when the plasma stagnates on axis. In the proceedings of the Ninth IEEE Pulsed Power Conference, we published results from system development tests. At this time, we have fielded seven tests in which the focus was on either vacuum switching or load physics. Four of the tests concentrated on the performance of a Plasma Flow Switch (PFS) which employed a 1/r mass distribution in the PFS barrel. Of the four tests, two had dummy loads and one had an implosion load. In addition, one of the tests broke down near the vacuum dielectric interface, and the result demonstrated what Procyon could deliver to an 18 nH load. We will summarize PFS results and the 18 nH test which is pertinent to upcoming solid/liquid liner experiments. On our other three tests, we eliminated the PFS switching and powered the z-pinch directly with the HEPP system. From the best of these direct drive tests we obtained 1.5 MJ of radiation in a 250 ns pulse, our best radiation pulse to date. We will also summarize direct drive test results. More details …
Date:
August 1, 1995
Creator:
Goforth, J.H.; Anderson, B.G. & Anderson, W.E.
Object Type:
Article
System:
The UNT Digital Library
Slimhole Handbook: Procedures and Recommendations for Slimhole Drilling and Testing in Geothermal Exploration
None
Date:
October 1, 1999
Creator:
Finger, John T.; Combs, Jim; Goranson, Colin; Hickox, Charles; Jacobson, Ronald D. & Polk, Gene
Object Type:
Report
System:
The UNT Digital Library
Vapor pressures and heats of vaporization of primary coal tars. Quarterly technical progress report, 1 January 1995--31 March 1995
The vapor pressure correlations that exist at present for coal tars are very crude and they are not considered reliable to even an order of magnitude when applied to tars. Sophisticated general correlative approaches are slowly being developed, based upon group contribution methods, or based upon some key functional features of the molecules. These are as yet difficult to apply to coal tars. The detailed group contribution methods, in which fairly precise structural information is needed, do not lend themselves well for application to very complex, poorly characterized coal tars. The methods based upon more global types of characterizations have not yet dealt much with the question of oxygenated functional groups. In short, only very limited correlations exist, and these are not considered reliable to even an order of magnitude when applied to tars. The present project seeks to address this important gap in the near term by direct measurement of vapor pressures of coal tar fractions, by application of well-established techniques and modifications thereof. The principal objectives of the program are to: (1) obtain data on the vapor pressures and heats of vaporization of tars from a range of ranks of coal, (2) develop correlations based on a minimum …
Date:
August 1, 1995
Creator:
Suuberg, E.M.; Oja, V. & Lilly, W.D.
Object Type:
Report
System:
The UNT Digital Library
Strontium isotopes in carbonate deposits at Crater Flat, Nevada
Strontium isotope studies of carbonates from soils, veins, eolian dust and Paleozoic basement samples near Crater Flat, southwest of Yucca Mountain, provide evidence for the origins of these materials. Vein and soil carbonates have nearly identical ranges of {sup 87}Sr/{sup 86}Sr ratios at the lower end of the pedogenic range. The average {sup 87}Sr/{sup 86}Sr of Paleozoic basement from Black Marble Hill is similar to the {sup 87}Sr/{sup 86}Sr in the eolian dust, perhaps indicating a local source for this material. Possible spring deposits have generally higher {sup 87}Sr/{sup 86}Sr than the other carbonates. These data are compared with similar data from areas east of Yucca Mountain. 7 refs., 5 figs.
Date:
January 1, 1991
Creator:
Marshall, B.D.; Futa, K.; Peterman, Z.E. & Stuckless, J.S.
Object Type:
Article
System:
The UNT Digital Library