Progress in developing very-high-density low-enriched-uranium fuels. (open access)

Progress in developing very-high-density low-enriched-uranium fuels.

Preliminary results from the postirradiation examinations of microplates irradiated in the RERTR-1 and -2 experiments in the ATR have shown several binary and ternary U-MO alloys to be promising candidates for use in aluminum-based dispersion fuels with uranium densities up to 8 to 9 g/cm{sup 3}. Ternary alloys of uranium, niobium, and zirconium performed poorly, however, both in terms of fuel/matrix reaction and fission-gas-bubble behavior, and have been dropped from further study. Since irradiation temperatures achieved in the present experiments (approximately 70 C) are considerably lower than might be experienced in a high-performance reactor, a new experiment is being planned with beginning-of-cycle temperatures greater than 200 C in 8-g U/cm{sup 3} fuel.
Date: February 19, 1999
Creator: Hayes, S. L.; Hofman, G. L.; Meyer, M. K; Snelgrove, J. L.; Strain, R. V. & Wiencek, T. C.
Object Type: Article
System: The UNT Digital Library
In situ spectroscopic ellipsometry as a surface sensitive tool to probe thin film growth. (open access)

In situ spectroscopic ellipsometry as a surface sensitive tool to probe thin film growth.

Sputtered thin film and multilayer x-ray mirrors are made routinely at the Advanced Photon Source (APS) for the APS users. Precise film growth control and characterization are very critical in fabricating high-quality x-ray mirrors. Film thickness calibrations are carried out using in situ and ex situ spectroscopic ellipsometry, interferometry, and x-ray scattering. To better understand the growth and optical properties of different thin film systems, we have carried out a systematic study of sputtered thin films of Au, Rh, Pg Pd, Cu, and Cr, using in situ ellipsometry. Multiple data sets were obtained in situ for each film material with incremental thicknesses and were analyzed with their correlation in mind. We found that in situ spectroscopic ellipsometry as a surface-sensitive tool can also be used to probe the growth and morphology of the thin film system. This application of in situ spectroscopic ellipsometry for metal thin film systems will be discussed.
Date: February 19, 1999
Creator: Liu, C.
Object Type: Article
System: The UNT Digital Library
THE STORY OF SIGMA HYPERNUCLEI - A MODERN FABLE. (open access)

THE STORY OF SIGMA HYPERNUCLEI - A MODERN FABLE.

The reality of {Sigma} hypernuclei has been the subject of intense concern among experimenters and theoreticians for more than 20 years. The possible existence of {Sigma} hypernuclei was first suggested by a pioneering experiment on a {sup 9}Be target at the CERN PS. There were reported to be two narrow ({Gamma} < 8 MeV) peaks in the continuum region. This finding was quite unexpected since the widths of {Sigma} states were believed to be large due to the strong conversion process. It is obvious that if such relatively long-lived systems were confirmed unambiguously by experiment, their masses and widths provide important constraints on the {Sigma}N effective interaction and its relation to the {Lambda}N and NN interactions. Since the {Sigma} carries isospin, the role of isospin and isospin conservation in hadronic reactions could be explored. This report stimulated a number of subsequent experiments at the BNL-AGS and KEK, along with further experiments with a specially created short kaon beam at the CERN PS. Experimental data were reported for different targets at different momenta and at different conditions. Various tagging techniques were employed to suppress backgrounds, but always at the expense of a reduction in statistical quality. Because of problems with resolution …
Date: February 19, 1999
Creator: CHRIEN,R.E.
Object Type: Article
System: The UNT Digital Library
3D dislocation dynamics: stress-strain behavior and hardening mechanisms in FCC and BCC metals (open access)

3D dislocation dynamics: stress-strain behavior and hardening mechanisms in FCC and BCC metals

A dislocation dynamics (DD) model for plastic deformation, connecting the macroscopic mechanical properties to basic physical laws governing dislocation mobility and related interaction mechanisms, has been under development. In this model there is a set of critical reactions that determine the overall results of the simulations, such as the stress-strain curve. These reactions are, annihilation, formation of jogs, junctions, and dipoles, and cross-slip. In this paper we discuss these reactions and the manner in which they influence the simulated stress- strain behavior in fcc and bcc metals. In particular, we examine the formation (zipping) and strength of dipoles and junctions, and effect of jogs, using the dislocation dynamics model. We show that the strengths (unzipping) of these reactions for various configurations can be determined by direct evaluation of the elastic interactions. Next, we investigate the phenomenon of hardening in metals subjected to cascade damage dislocations. The microstructure investigated consists of small dislocation loops decorating the mobile dislocations. Preliminary results reveal that these loops act as hardening agents, trapping the dislocations and resulting in increased hardening.
Date: February 19, 1999
Creator: Hirth, J P; Rhee, M; Zhib, H M & de la Rubia, T D
Object Type: Report
System: The UNT Digital Library
Overview of bunch length measurements. (open access)

Overview of bunch length measurements.

An overview of particle and photon beam bunch length measurements is presented in the context of free-electron laser (FEL) challenges. Particle-beam peak current is a critical factor in obtaining adequate FEL gain for both oscillators and self-amplified spontaneous emission (SASE) devices. Since measurement of charge is a standard measurement, the bunch length becomes the key issue for ultrashort bunches. Both time-domain and frequency-domain techniques are presented in the context of using electromagnetic radiation over eight orders of magnitude in wavelength. In addition, the measurement of microbunching in a micropulse is addressed.
Date: February 19, 1999
Creator: Lumpkin, A. H.
Object Type: Article
System: The UNT Digital Library
Preprocessing of backprojection images in the McClellan Nuclear Radiation Center tomography system (open access)

Preprocessing of backprojection images in the McClellan Nuclear Radiation Center tomography system

Neutron tomography is being investigated as a nondestructive technique for quantitative assessment of low atomic mass impurity concentration in metals. Neutrons maximize the sensitivity given their higher cross sections for low Z isotopes while tomography provides the three dimensional density information. The specific application is the detection of Hydrogen down to 200 ppm weight in aircraft engine compressor blades. A number of preprocessing corrections have been implemented for the backprojection images in order to achieve the detection requirements for a testing rate of three blades per hour. Among the procedures are corrections for neutron scattering and beam hardening. With these procedures the artifacts in tomographic reconstructions are shown to be less than the signal for 100 ppm hydrogen in titanium alloy samples.
Date: February 19, 1998
Creator: Gibbons, M. R., LLNL
Object Type: Report
System: The UNT Digital Library
A Novel Wire Scanner for High Intensity Pulsed Beams (open access)

A Novel Wire Scanner for High Intensity Pulsed Beams

A novel wire scanner has been developed with applications at linear accelerators where small beam spots or high intensities would otherwise destroy wires. A pattern of wires is supported on a thin membrane and remains in place even when punctured by the beam. Many scans can be made before the material needs to be replaced. Tests of the principle have been carried out at the Final Focus Test Beam at SLAC.
Date: February 19, 1999
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Solar system events at high spatial resolution (open access)

Solar system events at high spatial resolution

Until relatively recent advances in technology, astronomical observations from the ground were limited in image resolution by the blurring effects of earth's atmosphere. The blur extent, ranging typically from 0.5 to 2 seconds of arc at the best astronomical sights, precluded ground-based observations of the details of the solar system's moons, asteroids, and outermost planets. With the maturing of a high resolution image processing technique called speckle imaging the resolution limitation of the atmosphere can now be largely overcome. Over the past three years they have used speckle imaging to observe Titan, a moon of Saturn with an atmospheric density comparable to Earth's, Io, the volcanically active innermost moon of Jupiter, and Neptune, a gas giant outer planet which has continually changing planet-encircling storms. These observations were made at the world's largest telescope, the Keck telescope in Hawaii and represent the highest resolution infrared images of these objects ever taken.
Date: February 19, 1999
Creator: Baines, K H; Gavel, D T; Getz, A M; Gibbartd, S G; MacIntosh, B; Max, C E et al.
Object Type: Report
System: The UNT Digital Library
Mound Laboratory plutonium study: Presentation to the scientific review panel (open access)

Mound Laboratory plutonium study: Presentation to the scientific review panel

This paper describes the Mound plutonium study. The objectives of the project were to evaluate the inventory of plutonium 238 in the environment at Mound, determine the source, and alleviate potential health hazards. Analysis of soils, water, vegetation, fishes, and runoff were performed.
Date: February 19, 1975
Creator: Rogers, D. R.; Westendorf, W. H. & McClain, J. R.
Object Type: Report
System: The UNT Digital Library
DP: Parameter Display Page Program (open access)

DP: Parameter Display Page Program

The Parameter Display Page program (DP) is a Motif/X11-based program to allow easily configured, dynamic device and process variable monitoring and manipulation in the EPICS environment. DP provides a tabular data format for interactive viewing and manipulation of device and process variable statistics, as well as formatted PostScript output to files and printers. DP understands and operates in two (unfortunately disjoint at this time) namespaces in the EPICS environment ``devices`` and ``process variables``. The higher level namespace of devices includes Composite and Atomic Devices registered via the Device Access server; the lower level (flat) namespace is that of normal Process Variables accessible via Channel Access.
Date: February 19, 1994
Creator: Anderson, M.
Object Type: Report
System: The UNT Digital Library
Tank characterization report for single-shell tanks 241-T-201, 241-T-202, 241-T-203, and 241-T-204 (open access)

Tank characterization report for single-shell tanks 241-T-201, 241-T-202, 241-T-203, and 241-T-204

A major function of the Tank Waste Remediation System (TWRS) is to characterize waste in support of waste management and disposal activities at the Hanford Site. Analytical data from sampling and analysis, in addition to other available information about a tank are compiled and maintained in a tank characterization report (TCR). This report and its appendices serve as the TCR for the single-shell tank series consisting of 241-T-201, -T-202, -T-203, and -T-204. The objectives of this report are: (1) to use characterization data in response to technical issues associated with T-200 series tank waste and (2) to provide a standard characterization of this waste in terms of a best-basis inventory estimate. Section 2.0 summarizes the response to technical issues, Section 3.0 shows the best-basis inventory estimate, Section 4.0 makes recommendations about the safety status of the tank and additional sampling needs. The appendices contain supporting data and information. Appendix A contains historical information for 241-T-201 to T-204, including surveillance information, records pertaining to waste transfers and tank operations, and expected tank contents derived from a process knowledge-based computer program. Appendix B summarizes sampling events, sample data obtained before 1989, and the most current sampling results. Appendix C reports the statistical …
Date: February 19, 1998
Creator: Simpson, B.C.
Object Type: Report
System: The UNT Digital Library
Confidence Calculation with AMV+ (open access)

Confidence Calculation with AMV+

The iterative advanced mean value algorithm (AMV+), introduced nearly ten years ago, is now widely used as a cost-effective probabilistic structural analysis tool when the use of sampling methods is cost prohibitive (Wu et al., 1990). The need to establish confidence bounds on calculated probabilities arises because of the presence of uncertainties in measured means and variances of input random variables. In this paper an algorithm is proposed that makes use of the AMV+ procedure and analytically derived probability sensitivities to determine confidence bounds on calculated probabilities.
Date: February 19, 1999
Creator: Fossum, A. F.
Object Type: Article
System: The UNT Digital Library
Economic value of global weather measurements (open access)

Economic value of global weather measurements

Global sensor networks could support increased activity in a number of economic sectors. Potential benefits and the predicted time scales required to realize them are estimated. Benefits are particular compelling for fundamental reasons for aviation, hotels and restaurants, natural disasters, construction, agriculture, and apparel. These benefits can be captured by simple logistic approximations.
Date: February 19, 1999
Creator: Canavan, G. & Butterworth, J.
Object Type: Report
System: The UNT Digital Library
Supporting large-scale computational science (open access)

Supporting large-scale computational science

Business needs have driven the development of commercial database systems since their inception. As a result, there has been a strong focus on supporting many users, minimizing the potential corruption or loss of data, and maximizing performance metrics like transactions per second, or TPC-C and TPC-D results. It turns out that these optimizations have little to do with the needs of the scientific community, and in particular have little impact on improving the management and use of large-scale high-dimensional data. At the same time, there is an unanswered need in the scientific community for many of the benefits offered by a robust DBMS. For example, tying an ad-hoc query language such as SQL together with a visualization toolkit would be a powerful enhancement to current capabilities. Unfortunately, there has been little emphasis or discussion in the VLDB community on this mismatch over the last decade. The goal of the paper is to identify the specific issues that need to be resolved before large-scale scientific applications can make use of DBMS products. This topic is addressed in the context of an evaluation of commercial DBMS technology applied to the exploration of data generated by the Department of Energy`s Accelerated Strategic Computing …
Date: February 19, 1998
Creator: Musick, R.
Object Type: Article
System: The UNT Digital Library
WRAP low level waste (LLW) glovebox operational test report (open access)

WRAP low level waste (LLW) glovebox operational test report

The Low Level Waste (LLW) Process Gloveboxes are designed to: receive a 55 gallon drum in an 85 gallon overpack in the Entry glovebox (GBIOI); and open and sort the waste from the 55 gallon drum, place the waste back into drum and relid in the Sorting glovebox (GB 102). In addition, waste which requires further examination is transferred to the LLW RWM Glovebox via the Drath and Schraeder Bagiess Transfer Port (DO-07-201) or sent to the Sample Transfer Port (STC); crush the drum in the Supercompactor glovebox (GB 104); place the resulting puck (along with other pucks) into another 85 gallon overpack in the Exit glovebox (GB 105). The status of the waste items is tracked by the Data Management System (DMS) via the Plant Control System (PCS) barcode interface. As an item is moved from the entry glovebox to the exit glovebox, the Operator will track an items location using a barcode reader and enter any required data on the DMS console. The Operational Test Procedure (OTP) will perform evolution`s (described below) using the Plant Operating Procedures (POP) in order to verify that they are sufficient and accurate for controlled glovebox operation.
Date: February 19, 1998
Creator: Kersten, J.K.
Object Type: Report
System: The UNT Digital Library
High-power laser diodes at various wavelengths (open access)

High-power laser diodes at various wavelengths

High power laser diodes at various wavelengths are described. First, performance and reliability of an optimized large transverse mode diode structure at 808 and 941 nm are presented. Next, data are presented on a 9.5 kW peak power array at 900 nm having a narrow emission bandwidth suitable for pumping Yb:S-FAP laser materials. Finally, results on a fiber-coupled laser diode array at {approx}730 nm are presented.
Date: February 19, 1997
Creator: Emanuel, M. A.
Object Type: Article
System: The UNT Digital Library
The column density distribution of the Lyman-alpha forest: A measure of small scale power (open access)

The column density distribution of the Lyman-alpha forest: A measure of small scale power

Absorption lines in the Ly{alpha} forest can be thought of as peaks in neutral hydrogen density along lines of sight. The column density distribution (the number density of absorption lines as a function of column density) is then a statistic of density peaks, which contains information about the underlying power spectrum. In particular, we show that the slope of the distribution provides a measure of power on scales smaller than those probed by studies of present day large scale structure. 2 refs., 1 fig.
Date: February 19, 1997
Creator: Hui, Lam; Gnedin, Nickolay Y. & Zhang, Yu
Object Type: Report
System: The UNT Digital Library
Thermal Performance Analysis of Repository Codisposal Waste Packages Containing Aluminum-Clad Spent Nuclear Fuel (open access)

Thermal Performance Analysis of Repository Codisposal Waste Packages Containing Aluminum-Clad Spent Nuclear Fuel

The leading codisposal waste package (WP) design proposes that a central DOE Aluminum-clad Spent Nuclear Fuel (Al-SNF) canister be surrounded by five defense waste process facility (DWPF) glass log canisters, and placed into a WP in the Mined Geologic Disposal System (MGDS).
Date: February 19, 1999
Creator: Lee, Si Young
Object Type: Article
System: The UNT Digital Library
Analysis of Sr{Sub 5{Minus}X}Ba{Sub X}(Po{Sub 4}){Sub 3}F:Yb{Sup 3+} Crystals for Improved Laser Performance With Diode-Pumping (open access)

Analysis of Sr{Sub 5{Minus}X}Ba{Sub X}(Po{Sub 4}){Sub 3}F:Yb{Sup 3+} Crystals for Improved Laser Performance With Diode-Pumping

Crystals of Yb{sup 3+}:Sr{sub 1-x}Ba{sub x}(PO{sub 4}){sub 3}F (0 < x < 5) have been investigated as a means to obtain broader absorption bands than are currently available with Yb{sup 3+}:S-FAP [Yb{sup 3+}: Sr{sub 5}(PO{sub 4}){sub 3}F], thereby improving diode-pumping efficiency for high peak power applications. Large diode-arrays have a FWHM pump band of >5 nm while the FWHM of the 900 nm absorption band for Yb:S-FAP is 5.5 nm; therefore, a significant amount of pump power can be wasted due to the nonideal overlap. Spectroscopic analysis of Yb:Sr{sub 5-x}Ba{sub x}-FAP crystals indicates that adding barium to the lattice increases the pump band to 13-16 run which more than compensates for the diode-array pump source without a detrimental reduction in absorption cross section. However, the emission cross section decreases by approximately half with relatively no effect on the emission lifetime. The small signal gain has also been measured and compared to the parent material Yb:S-FAP and emission cross sections have been determined by the method of reciprocity, the Filchtbauer-Ladenburg method, and small signal gain. Overall, Yb{sup 3+}:Sr{sub 5-x}Ba{sub x}(PO{sub 4}){sub 3}F crystals appear to achieve the goal of nearly matching the favorable thermal and laser performance properties of Yb:S-FAP while …
Date: February 19, 1997
Creator: Schaffers, K. I.; Bayramian, A. J.; Marshall, C. D.; Tassano, J. B. & Payne, S. A.
Object Type: Article
System: The UNT Digital Library
[Geothermal system temperature-depth database and model for data analysis]. 4. quarterly technical progress report (open access)

[Geothermal system temperature-depth database and model for data analysis]. 4. quarterly technical progress report

The activities that have been carried out this quarter include continued planning and development of the geothermal system thermal-well data-base that will be one of the main contract results. The authors are continuing to modify the specifications of the database and continuing initial input. They have added several additional areas to their inventory of the geothermal areas for which data are available in the literature (published and open file) and on open file as described in the third quarterly report. A map was enclosed with the second quarterly report that gave the preliminary location of sites of various categories of wells. They will include a revised map with the next quarterly report when all of the sites, including the new ones described below, have been located and added to the index map. In particular in the last quarter the authors have added about 100 wells in west Texas in the transPecos region from a previously proprietary report that they recently obtained. In addition they have made arrangements to obtain thermal data collected by AMAX Geothermal during their exploration activities. The number of wells is large, several hundred, and the sites are spread throughout the western US from New Mexico and …
Date: February 19, 1998
Creator: Blackwell, D.D.
Object Type: Report
System: The UNT Digital Library
CW and Q-switched performance of a diode end-pumped Yb:YAG laser. Revision 1 (open access)

CW and Q-switched performance of a diode end-pumped Yb:YAG laser. Revision 1

Using an end-pumped technology developed at LLNL we have demonstrated a Yb:YAG laser capable of delivering up to 434 W of CW power and 226 W of Q-switched power. In addition, we have frequency doubled the output to 515 nm using a dual crystal scheme to produce 76 W at 10 kHz in a 30 ns pulse length.
Date: February 19, 1997
Creator: Bibeau, C.; Beach, R.; Ebbers, C.; Emanuel, M. & Skidmore, J.
Object Type: Article
System: The UNT Digital Library
Status of irradiations performed by fuel & target irradiation technology for BNW as of January 31, 1970 (open access)

Status of irradiations performed by fuel & target irradiation technology for BNW as of January 31, 1970

This document presents details of the status of irradiations performed by Fuel and Target Irradiation Technology for BNW as of January 31, 1970.
Date: February 19, 1970
Creator: Barker, L. V.
Object Type: Report
System: The UNT Digital Library
Long-term criticality control in radioactive waste disposal facilities using depleted uranium (open access)

Long-term criticality control in radioactive waste disposal facilities using depleted uranium

Plant photosynthesis has created a unique planetary-wide geochemistry - an oxidizing atmosphere with oxidizing surface waters on a planetary body with chemically reducing conditions near or at some distance below the surface. Uranium is four orders of magnitude more soluble under chemically oxidizing conditions than it is under chemically reducing conditions. Thus, uranium tends to leach from surface rock and disposal sites, move with groundwater, and concentrate where chemically reducing conditions appear. Earth`s geochemistry concentrates uranium and can separate uranium from all other elements except oxygen, hydrogen (in water), and silicon (silicates, etc). Fissile isotopes include {sup 235}U, {sup 233}U, and many higher actinides that eventually decay to one of these two uranium isotopes. The potential for nuclear criticality exists if the precipitated uranium from disposal sites has a significant fissile enrichment, mass, and volume. The earth`s geochemistry suggests that isotopic dilution of fissile materials in waste with {sup 238}U is a preferred strategy to prevent long-term nuclear criticality in and beyond the boundaries of waste disposal facilities because the {sup 238}U does not separate from the fissile uranium isotopes. Geological, laboratory, and theoretical data indicate that the potential for nuclear criticality can be minimized by diluting fissile materials with-{sup …
Date: February 19, 1997
Creator: Forsberg, Charles W.
Object Type: Article
System: The UNT Digital Library
Acceptable knowledge summary report for combustible/noncombustible, metallic, and HEPA filter waste resulting from {sup 238}Pu fabrication activities (open access)

Acceptable knowledge summary report for combustible/noncombustible, metallic, and HEPA filter waste resulting from {sup 238}Pu fabrication activities

All transuranic (TRU) waste must be sufficiently characterized and certified before it is shipped to the Waste Isolation Pilot Plant (WIPP). The US Environmental Protection Agency (EPA) allows use of acceptable knowledge (AK) for waste characterization. EPA uses the term AK in its guidance document and defines AK and provides guidelines on how acceptable knowledge should be obtained and documented. This AK package has been prepared in accordance with Acceptable Knowledge Documentation (TWCP-QP-1.1-021,R.2). This report covers acceptable knowledge information for five waste streams generated at TA-55 during operations to fabricate various heat sources using feedstock {sup 238}Pu supplied by the Savannah River Site (SRS). The {sup 238}Pu feedstock itself does not contain quantities of RCRA-regulated constituents above regulatory threshold limits, as known from process knowledge at SRS and as confirmed by chemical analysis. No RCRA-regulated chemicals were used during {sup 238}Pu fabrication activities at TA-55, and all {sup 238}Pu activities were physically separated from other plutonium processing activities. Most of the waste generated from the {sup 238}Pu fabrication activities is thus nonmixed waste, including waste streams TA-55-43, 45, and 47. The exceptions are waste streams TA-55-44, which contains discarded lead-lined rubber gloves used in the gloveboxes that contained the {sup …
Date: February 19, 1998
Creator: Rogers, P.S.Z. & Foxx, C.L.
Object Type: Report
System: The UNT Digital Library