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Investigation of a fossil geothermal system, Hamblin-Cleopatra Volcano, Clark County, Nevada. Final technical report

Description: The Hamblin-Cleopatra volcano, selected for study because erosion and fault displacement have exposed the entire volcanic succession, the intrusive core, a radial dike systems, and sedimentary and volcanic rocks that predate and postdate the volcano, was investigated to estimate the proportions of igneous materials forming lava flows, pyroclastic deposits, intrusive bodies, and reworked debris. Chemical changes in the magma throughout the active period of the volcano were documented. The geothermal system active within the pile after activity ceased was reconstructed. (ACR)
Date: July 28, 1986
Creator: Barker, D.S.
Partner: UNT Libraries Government Documents Department

Improvement and verification of fast reactor safety analysis techniques. Progress report, July 1-September 30, 1979

Description: The physical properties of the initial and final liquid phase of the Dimethyl Sulfoxide-Acetyl Chloride reaction system with either Acetone or Benzene as solvent are reported together with the method of collection. These properties include heat capacity, thermal conductivity, viscosity, density, heat of vaporization and thermal coefficient of volumetric expansion. A method of interpolation between initial and final liquid properties is described.
Date: January 1, 1979
Creator: Barker, D.H. & Wiberg, D.V.
Partner: UNT Libraries Government Documents Department

Improvement and verification of fast reactor safety analysis techniques. Progress report, April 1, 1979-June 30, 1979

Description: This report details a mathematical model for the dissipation of heat from an internally heated liquid pool which is contained in a hollow cylinder of finite inside and outside diameter. The model includes a temperature profile for the previously described cylinder, empirical correlations for Nusselt numbers at the walls of the container and a film theory correction of the heat transfer coefficients for mass transfer. Also included in this report is a description of the experimental work conducted as a preliminary step to verification or rejection of the proposed mathematical model. This experimental work consisted of reacting Dimethyl Sulfoxide (DMSO) with Acetyl Chloride (AC), using Acetone as a solvent, in a hollow wax cylinder and observing the geometry and dimensions of the melt.
Date: January 1, 1979
Creator: Barker, D.H. & Wiberg, D.V.
Partner: UNT Libraries Government Documents Department

Improvement and verification of fast reactor safety analysis techniques. Progress report, October 1, 1979-March 31, 1980. [LMFBR]

Description: Several of the time dependent properties of the dimethyl sulfoxide-acetyl chloride reaction system were determined. The volume of a wax cylinder melted by conducting a dimethyl sulfoxide-acetyl chloride reaction in the vessel was compared with the melted volume calculated using several different heat transfer correlations. It was found that a laminar flow at the wall model provided the most accurate calculation of the observed melted volume.
Date: January 1, 1980
Creator: Barker, D.H. & Wiberg, D.V.
Partner: UNT Libraries Government Documents Department

Improvement and verification of fast reactor safety analysis techniques. Progress report, October 1, 1977--December 31, 1977

Description: The critical superficial vapor velocity was measured for an open vessel system with chemically produced internal heat. The measured value was within experimental error of the value predicted by the Kutateladze stability criterion. The greatest error induced was in the measurement of the energy generation rate. The effects of mixtures were taken into account. Further work suggestions are also presented.
Date: January 1, 1977
Creator: Barker, D.H. & Wheeler, P.A.
Partner: UNT Libraries Government Documents Department

Device control at CEBAF

Description: CEBAF has undergone a major conversion of its accelerator control system from TACL to EPICS, affecting device control for the RF system, magnets, the machine protection system, the vacuum and valves, and the diagnostic systems including beam position monitors, harps, and the camera and solenoid devices (beam viewers, faraday cups, optical transition radiation viewers, synchrotron radiation monitor, etc.). Altogether these devices require approximately 125,000 EPICS database records. The majority of these devices are controlled through CAMAC; some use embedded microprocessors (RF and magnets), and newer interfaces are in VME. The standard EPICS toolkit was extended to include a driver for CAMAC which supports dual processors on one serial highway, custom database records for magnets and BPMs, and custom data acquisition tasks for the BPMs. 2 refs., 1 tab.
Date: August 1, 1996
Creator: Schaffner, S.; Barker, D. & Bookwalter, V.
Partner: UNT Libraries Government Documents Department

The Effects of Heterogeneities on Seismic Wave Propagation in the Climax Stock

Description: The Comprehensive Nuclear Test-Ban Treaty requires the ability to detect low-yield (less than 150kton) nuclear events. This kind of monitoring can only be done seismically on a regional scale (within 2000km). At this level, it is difficult to distinguish between low-yield nuclear events and non-nuclear events of similar magnitude. In order to confidently identify a nuclear event, a more detailed understanding of nuclear seismic sources is needed. In particular, it is important to know the effects of local geology on the seismic signal. This study focuses on P-wave velocity in heterogeneous granitoid. The Source Physics Experiment (SPE) is currently performing low-yield tests with chemical explosives at the Nevada National Security Site (NNSS). The exact test site was chosen to be in the Climax Stock, a cretaceous granodiorite and quartz-monzonite pluton located in Area 15 of the NNSS. It has been used in the past for the Hard Hat and Pile Driver nuclear tests, which provided legacy data that can be used to simulate wave propagation. The Climax Stock was originally chosen as the site of the SPE partly because of its assumed homogeneity. It has since been discovered that the area of the stock where the SPE tests are being performed contains a perched water table. In addition, the stock is known to contain an extensive network of faults, joints, and fractures, but the exact effect of these structural features on seismic wave velocity is not fully understood. The SPE tests are designed to seismically capture the explosion phenomena from the near- to the far-field transition of the seismic waveform. In the first SPE experiment, 100kg of chemical explosives were set off at a depth of 55m. The blast was recorded with an array of sensors and diagnostics, including accelerometers, geophones, rotational sensors, short-period and broadband seismic sensors, Continuous Reflectometry ...
Date: December 1, 2011
Creator: Hagan Webb, C., Snelson, C. M., White, R., Emmitt, R., Barker, D., Abbott, R., Bonal, N.
Partner: UNT Libraries Government Documents Department

Effect of powder characteristics on the {alpha}-TO-{beta} Si{sub 3}N{sub 4} transformation kinetics

Description: {beta}-phase nucleation and growth is an important step in the microstructure development of Si{sub 3}N{sub 4} ceramics. Samples containing different powder types, sintering additives and {alpha}/{beta} ratios were heated at intermediate temperatures and times to monitor the phase changes taking place. The rate of transformation was mainly dependent on the powder surface area and starting {beta}-content. It was observed that additions of {beta}-Si{sub 3}N{sub 4} increased the rate of transformation.
Date: April 1, 1997
Creator: Tiegs, T.N.; Montgomery, F.C.; Schroeder, J.L.; Barker, D.L. & Menchhofer, P.A.
Partner: UNT Libraries Government Documents Department

Gas pressure sintering of silicon nitride to optimize fracture toughness

Description: Gas-pressure sintering (GPS) can be used to densify silicon nitride containing a wide variety of sintering additives. Parameters affecting the sintering behavior include densification temperature, densification time, grain growth temperature, grain growth time and heating rates. The Si{sub 3}N{sub 4}-6% Y{sub 2}O{sub 3}-2% A1{sub 2}O{sub 3} samples sintered to high densities at all conditions used in the present study, whereas the Si{sub 3}N{sub 4}-Sr{sub 2}La{sub 4}Yb{sub 4}(SiO{sub 4}){sub 6}O{sub 2} samples required the highest temperatures and longest times to achieve densities {ge}98 % T. D. The main effect on the fracture toughness for Si{sub 3}N{sub 4}-6% Y{sub 2}O{sub 3}-2% A1{sub 2}O{sub 3} samples was the use of a lower densification temperature, which was 1900C in the present study. For the Si{sub 3}N{sub 4}-Sr{sub 2}La{sub 4}Yb{sub 4}SiO4{sub 4}){sub 6}O{sub 2} composition, fracture toughness was sensitive to and improved by a slower heating rate (10c/min), a lower densification temperature (1900`), a higher grain growth temperature (2000C), and a longer grain growth time (2 h).
Date: June 1, 1995
Creator: Tiegs, T.N.; Nunn, S.D.; Beavers, T.M.; Menchhofer, P.A.; Barker, D.L. & Coffey, D.W.
Partner: UNT Libraries Government Documents Department

Radiation-Driven Shock and Debris Propagation Down a Partitioned Pipe

Description: Two experiments have been performed to measure the effects of pulsed radiation loads on the front of small tubular structures, using as an energy source the X-ray fluence produced by a Z-pinch at the Sandia National Laboratories Z Facility. The project had two major goals: to establish the feasibility of using the Z machine to study the phenomenology associated with debris generation and propagation down tubular structures with partitions; and to use the resultant experimental data to validate numerical hydrocodes (shock physics codes) so that we have confidence in their use in analyzing these types of situations. Two tubular aluminum structures (5 and 10 cm long and 1 cm inside diameter) were prepared, with aluminum partitions located at the front, halfway down the pipe, and at the rear. Interferometry (VISARS) provided multiple velocity histories for all of the partitions. In both experiments, the first barrier, which was exposed directly to the x-ray fluence, was launched into the pipe at a velocity of {approximately}2 km/s, accelerating to give a mean velocity of approximately 2.6 km/s. Loss of plate integrity is inferred from the dispersed launch of the second partition at approx. 1 km/s. Wall shocks propagating at 4.5 km/s were inferred, although strain gage measurements did not succeed. Post-test metallography showed evidence of melting and partial vaporization of the plates, and turbulent mixing with material from the walls. Calculations qualitatively agree with the observed results, but slightly overpredict debris velocity, possibly due to overestimates of total energy fluence. An application for this work is the study of techniques for line-of-sight shock and debris mitigation on high-power pulse-power facilities such as Z and its follow-on machines.
Date: June 13, 2000
Partner: UNT Libraries Government Documents Department

Effect of composition on the processing and properties of sintered reaction-bonded silicon nitride

Description: The type of silicon powder and sintering additive were found to influence the processing and final mechanical properties of sintered reaction bonded silicon nitride. High purity silicon powders produced low {alpha}-Si{sub 3}N{sub 4} content during nitridation. The Si powder type had no apparent effect on densification. More complete nitridation and higher room temperature mechanical properties were observed for the Si powders with higher Fe contents. However, the higher Fe contents resulted in greater high temperature strength degradation and so there was better high temperature strength retention with the higher purity Si. High {alpha}-Si{sub 3}N{sub 4} contents were found after nitridation with {alpha}-Si{sub 3}N{sub 4} seeded materials and with MgO-Y{sub 2}O{sub 3} as the sintering additive. Densification was inhibited by refractory additives, such as Y{sub 2}O{sub 3}-SiO{sub 2}. The highest room temperature strength and fracture toughness values correlated to high nitrided {alpha}-Si{sub 3}N{sub 4} contents. The high temperature strength behavior was similar for all additive types.
Date: April 1, 1996
Creator: Tiegs, T.N.; Kiggans, J.O.; Montgomery, F.C.; Lin, H.T.; Barker, D.L.; Snodgrass, J.D. et al.
Partner: UNT Libraries Government Documents Department

Development of diagnostics for high-energy petawatt pulses

Description: Applications accessed by high energy petawatt (HEPW) lasers require complete, single-shot characterization of pulse spatial, temporal, and energy characteristics. We describe techniques that enable single-shot characterization of the temporal shape and pulse contrast of HEPW pulses with >10{sup 8} dynamic range over a ns-temporal window. Approaches to measure pulse durations that span two orders of magnitude will be discussed. Finally, we describe a novel implementation of spectrally dispersed two-beam interferometry for measurement of the phase difference between two HEPW pulses. This technique can be applied to dispersion and B-integral measurements in a HEPW system, as well as to achieve precise timing of nanosecond pulses. Lastly, spectrally dispersed interferometry represents an ideal technique to enable coherent addition of HEPW pulses for production of ultrahigh intensities.
Date: June 15, 2006
Creator: Jovanovic, I; Hernandez, J; Appel, G; Barker, D; Betts, S; Brewer, W et al.
Partner: UNT Libraries Government Documents Department