Tests and Calibration of the NIF Neutron Time of Flight Detectors (open access)

Tests and Calibration of the NIF Neutron Time of Flight Detectors

The National Ignition Facility (NIF) Neutron Time of Flight (NTOF) diagnostic will measure neutron yield and ion temperature in all NIF campaigns in DD, DT, and THD* implosions. The NIF NTOF diagnostic is designed to measure neutron yield from 109 to 2 x 1019. The NTOF consists of several detectors of varying sensitivity located on the NIF at about 5 m and 20 m from the target. Production, testing, and calibration of the NIF NTOF detectors have begun at the Laboratory for Laser Energetics (LLE). Operational tests of the NTOF detectors were performed on several facilities including the OMEGA laser at LLE and the Titan laser at Lawrence Livermore National Laboratory (LLNL). Neutron calibrations were carried out on the OMEGA laser. Results of the NTOF detectors tests and calibration will be presented. *(D = deuterium, T = tritium, H = hydrogen)
Date: May 15, 2008
Creator: Ali, Z. A.; Glebov, V. Yu.; Cruz, M.; Duffy, T.; Stoeckl, C.; Roberts, S. et al.
Object Type: Article
System: The UNT Digital Library
Control Rod Studies for Enigma Configurations. (open access)

Control Rod Studies for Enigma Configurations.

None
Date: September 15, 2006
Creator: Aliberti, G.; Taiwo, T. A.; Palmiotti, G.; Tommasi, J. & Jacqmin,R.
Object Type: Report
System: The UNT Digital Library
ALPS - advanced limiter-divertor plasma-facing systems. (open access)

ALPS - advanced limiter-divertor plasma-facing systems.

The Advanced Limiter-divertor Plasma-facing Systems (ALPS) program was initiated in order to evaluate the potential for improved performance and lifetime for plasma-facing systems. The main goal of the program is to demonstrate the advantages of advanced limiter/divertor systems over conventional systems in terms of power density capability, component lifetime, and power conversion efficiency, while providing for safe operation and minimizing impurity concerns for the plasma. Most of the work to date has been applied to free surface liquids. A multi-disciplinary team from several institutions has been organized to address the key issues associated with these systems. The main performance goals for advanced limiters and diverters are a peak heat flux of >50 MW/m{sup 2},elimination of a lifetime limit for erosion, and the ability to extract useful heat at high power conversion efficiency ({approximately}40%). The evaluation of various options is being conducted through a combination of laboratory experiments, modeling of key processes, and conceptual design studies. The current emphasis for the work is on the effects of free surface liquids on plasma edge performance.
Date: September 15, 1999
Creator: Allain, J. P.; Bastasz, R.; Brooks, J. N.; Evans, T.; Hassanein, A.; Luckhardt, S. et al.
Object Type: Article
System: The UNT Digital Library
The Snowmass points and slopes : benchmarks for SUSY searches. (open access)

The Snowmass points and slopes : benchmarks for SUSY searches.

The ''Snowmass Points and Slopes'' (SPS) are a set of benchmark points and parameter lines in the MSSM parameter space corresponding to different scenarios in the search for Supersymmetry at present and future experiments. This set of benchmarks was agreed upon at the 2001 ''Snowmass Workshop on the Future of Particle Physics'' as a consensus based on different existing proposals.
Date: April 15, 2002
Creator: Allanach, B. C.; Battaglia, M.; Blair, G. A.; Carena, M.; De Roeck, A. & Wagner, C. E. M.
Object Type: Article
System: The UNT Digital Library
Design and Performance Characteristics of the ORNL AdvancedMicroscopy Laboratory and JEOL 2200FS-AC Aberration-CorrectedSTEM/TEM (open access)

Design and Performance Characteristics of the ORNL AdvancedMicroscopy Laboratory and JEOL 2200FS-AC Aberration-CorrectedSTEM/TEM

At ORNL, the new Advanced Microscopy Laboratory (AML) has recently been completed, with two aberration-corrected instruments installed, and two more planned in the near future to fill the 4-laboratory building. The installed JEOL 2200FS-AC has demonstrated aTEM information limit of 0.9A. This limit is expected given the measured instrument parameters (HT and OL power supply stabilities, beam energy spread, etc.), and illustrates that the environmental influences are not adversely affecting the instrument performance. In STEM high-angle annular dark-field (HA-ADF) mode, images of a thin Si crystal in<110>zone axis orientation, after primary aberrations in the illuminating beam were optimally corrected, showed a significant vibration effect. The microscope is fitted with three magnetically levitated turbo pumps (one on the column at about the specimen position,and two near floor level) that pump the Omega energy filter and detector chamber. These pumps run at 48,000 rpm, precisely equivalent to 800Hz. It was determined that the upper turbo pump was contributing essentially all of the 800Hz signal to the image, and in fact that the pump was defective. After replacing the pump with one significantly quieter than the original, the Si atomic column image and associated diffractogram(Fig. 4b) show a much-reduced effect of the 800Hz …
Date: February 15, 2005
Creator: Allard, Lawrence F.; Blom, Douglas A.; O'Keefe, Michael A. & Mishina, S.
Object Type: Article
System: The UNT Digital Library
Sorption and diffusion studies of Pu(IV) and Pu(V)-EDTA onto and through Hanford soil (open access)

Sorption and diffusion studies of Pu(IV) and Pu(V)-EDTA onto and through Hanford soil

Plutonium production at U.S. Department of Energy Hanford site has created massive amounts of radioactive and mixed wastes. Over 1.3 trillion liters of liquid waste have been discharged into the ground, the largest part of which has been absorbed by the upper soil layers with a small fraction migrating into the groundwater. Approximately 350 million liters of other low and high-level mixed wastes were stored in underground tanks between 1944 and 1980. These tanks contain organic materials that were introduced during the production and processing of plutonium, such as ethylenediametetraacetic acid (EDTA), tributyl phosphate, hexone, paraffin hydrocarbon and other minor organic and inorganic components. The quantity of EDTA is estimated to be 83 metric tons in the underground tanks. Several single-shell tanks are known or suspected to have leaked. It was reported that since 1995, approximately four million liters of mixed waste might have entered the soil beneath the single-shell tanks. This volume of waste is estimated to contain as much as one million curies of radioactivity.
Date: September 15, 1999
Creator: Allen, P G; Hakem, N L & Sylwester, E R
Object Type: Article
System: The UNT Digital Library
MICROCLIMATOLOGY OF OGOTORUK VALLEY. Preliminary Report No. 1 (open access)

MICROCLIMATOLOGY OF OGOTORUK VALLEY. Preliminary Report No. 1

None
Date: December 15, 1960
Creator: Allen, P. W.; Van der Hoven, I. & Weedfall, R. O.
Object Type: Report
System: The UNT Digital Library
Groundwater Level Status Report for 2005 Los Alamos National Laboratory (open access)

Groundwater Level Status Report for 2005 Los Alamos National Laboratory

The status of groundwater level monitoring at Los Alamos National Laboratory (LANL) in 2005 is provided in this report. The Groundwater Level Monitoring Project was instituted in 2005 to provide a framework for the collection and processing of quality controlled groundwater level data. This report summarizes groundwater level data for 137 monitoring wells, including 41 regional aquifer wells, 22 intermediate wells, and 74 alluvial wells. Pressure transducers were installed in 118 monitoring wells for continuous monitoring of groundwater levels. Time-series hydrographs of groundwater level data are presented along with pertinent construction and location information for each well.
Date: May 15, 2006
Creator: Allen, S. P. & Koch, R. J.
Object Type: Report
System: The UNT Digital Library
Radiation-induced segregation and void swelling in 304 stainless steel. (open access)

Radiation-induced segregation and void swelling in 304 stainless steel.

None
Date: June 15, 2000
Creator: Allen, T. R.; Cole, J. I. & Kenik, E. A.
Object Type: Article
System: The UNT Digital Library
Dose-to-Man From SRP Waste: Sensitivity to Leaching and Rock Properties (open access)

Dose-to-Man From SRP Waste: Sensitivity to Leaching and Rock Properties

This report summarizes results of a sensitivity analysis that predicts which features of the waste form and barrier system will have the greatest impact on dose to man.
Date: October 15, 2001
Creator: Allender, J.S.
Object Type: Report
System: The UNT Digital Library
Characterization of Surplus Plutonium for Disposition Options (open access)

Characterization of Surplus Plutonium for Disposition Options

The United States (U.S.) has identified 61.5 metric tons (MT) of plutonium that is permanently excess to use in nuclear weapons programs, including 47.2 MT of weapons-grade plutonium. Except for materials that remain in use for programs outside of national defense, including programs for nuclear-energy development, the surplus inventories will be stored safely by the Department of Energy (DOE) and then transferred to facilities that will prepare the plutonium for permanent disposition. Some items will be disposed as transuranic waste, low-level waste, or spent fuel. The remaining surplus plutonium will be managed through: (1) the Mixed Oxide (MOX) Fuel Fabrication Facility (FFF), to be constructed at the Savannah River Site (SRS), where the plutonium will be converted to fuel that will be irradiated in civilian power reactors and later disposed to a high-level waste (HLW) repository as spent fuel; (2) the SRS H-Area facilities, by dissolving and transfer to HLW systems, also for disposal to the repository; or (3) alternative immobilization techniques that would provide durable and secure disposal. From the beginning of the U.S. program for surplus plutonium disposition, DOE has sponsored research to characterize the surplus materials and to judge their suitability for planned disposition options. Because many …
Date: July 15, 2008
Creator: Allender, Jeffrey S.; Moore, Edwin N. & Davies, Scott H.
Object Type: Article
System: The UNT Digital Library
Origin of the Time-Dependence of Wet Oxidation of AlGaAs (open access)

Origin of the Time-Dependence of Wet Oxidation of AlGaAs

The time-dependence of the wet oxidation of high-Al-content AlGaAs can be either linear, indicating reaction-rate limitation, or parabolic, indicating diffusion-limited rates. The transition from linear to parabolic time dependence can be explained by the increased rate of the formation of intermediate As{sub 2}O{sub 3} vs. its reduction to elemental As. A steadily increasing thickness of the As{sub 2}O{sub 3}-containing region at the oxidation front will shift the process from the linear to the parabolic regime. This shift from reaction-rate-limited (linear) to diffusion-limited (parabolic) time dependence is favored by increasing temperature or increasing Al mole fraction.
Date: February 15, 1999
Creator: Allerman, A. A.; Ashby, C. I. H.; Bridges, M. M.; Hammons, B. E. & Hou, H. Q.
Object Type: Article
System: The UNT Digital Library
GaAs Self-Aligned JFETS with Carbon-Doped P+ Region (open access)

GaAs Self-Aligned JFETS with Carbon-Doped P+ Region

Self-aligned JFETs with a carbon-doped p{sup +} region have been reported for the first time. For these JFETs, both the channel and p{sup +} region were grown by metal organic chemical vapor deposition (MOCVD) and are termed epitaxial JFETs in this study. The epitaxial JFETs were compared to ion implanted JFETs of similar channel doping and threshold voltage. Both JFETs were fabricated using the same self-aligned process for doping the source and drain regions of the JFET and for eliminating excess gate capacitance of conventional JFETs. The gate turn-on voltage for the epitaxial JFETs was 1.06 V, about 0.1 V higher than for the implanted JFETs. The reverse breakdown voltage was similar for both JFETs but the reverse gate leakage current of the epitaxial JFETs was 1-3 orders of magnitude less than the implanted JFETs. The epitaxial JFETs also showed higher transconductance and lower knee voltage than the implanted JFETs.
Date: February 15, 1999
Creator: Allerman, A. A.; Baca, A. G.; Chang, P. C. & Drummond, T. J.
Object Type: Article
System: The UNT Digital Library
Targeted discovery of glycoside hydrolases from a switchgrass-adapted compost community (open access)

Targeted discovery of glycoside hydrolases from a switchgrass-adapted compost community

Development of cellulosic biofuels from non-food crops is currently an area of intense research interest. Tailoring depolymerizing enzymes to particular feedstocks and pretreatment conditions is one promising avenue of research in this area. Here we added a green-waste compost inoculum to switchgrass (Panicum virgatum) and simulated thermophilic composting in a bioreactor to select for a switchgrass-adapted community and to facilitate targeted discovery of glycoside hydrolases. Small-subunit (SSU) rRNA-based community profiles revealed that the microbial community changed dramatically between the initial and switchgrass-adapted compost (SAC) with some bacterial populations being enriched over 20-fold. We obtained 225 Mbp of 454-titanium pyrosequence data from the SAC community and conservatively identified 800 genes encoding glycoside hydrolase domains that were biased toward depolymerizing grass cell wall components. Of these, {approx}10% were putative cellulases mostly belonging to families GH5 and GH9. We synthesized two SAC GH9 genes with codon optimization for heterologous expression in Escherichia coli and observed activity for one on carboxymethyl cellulose. The active GH9 enzyme has a temperature optimum of 50 C and pH range of 5.5 to 8 consistent with the composting conditions applied. We demonstrate that microbial communities adapt to switchgrass decomposition using simulated composting condition and that full-length genes can …
Date: November 15, 2009
Creator: Allgaier, M.; Reddy, A.; Park, J. I.; Ivanova, N.; D'haeseleer, P.; Lowry, S. et al.
Object Type: Article
System: The UNT Digital Library
Assessing Risk of Innovation (open access)

Assessing Risk of Innovation

Today's manufacturing systems and equipment must perform at levels thought impossible a decade ago. Companies must push operations, quality, and efficiencies to unprecedented levels while holding down costs. In this new economy, companies must be concerned with market shares, equity growth, market saturation, and profit. U.S. manufacturing is no exception and is a prime example of businesses forced to adapt to constant and rapid changes in customer needs and product mixes, giving rise to the term ''Agile Manufacturing''. The survival and ultimate success of the American Manufacturing economy may depend upon its ability to create, innovate, and quickly assess the impact that new innovations will have on its business practices. Given the need for flexibility, companies need proven methods to predict and measure the impact that new technologies and strategies will have on overall plant performance from an enterprise perspective. The Value-Derivative Model provides a methodology and approach to assess such impacts in terms of energy savings, production increases, quality impacts, emission reduction, and maintenance and operating costs as they relate to enabling and emerging technologies. This is realized by calculating a set of first order sensitivity parameters obtained from expanding a Taylor Series about the system's operating point. These …
Date: August 15, 2001
Creator: Allgood, GO
Object Type: Article
System: The UNT Digital Library
Antiprotons and the Crystal Ball (open access)

Antiprotons and the Crystal Ball

During the 1998 running of the Crystal Ball experiment, a couple of brief test runs were done with the C6 beamline tuned to produce antiprotons. Specifically, one shift on July 29th produced runs 329-334 with the beam momentum set for 650 MeV/c, run 355 was done on July 31st with a 550 MeV/c beam momentum, and run 926-929 were obtained in a single shift on November 3rd, also with a beam momentum of 550 MeV/c. The beam tune for the November data was greatly superior to that of the July data, however. Therefore, only the November data have been analyzed in detail, and the results of this analysis are presented in this note. Due to the paucity of statistics that were obtained, it was decided not to attempt to publish the results. However, the results are valuable as a tool for planning a possible future program of dedicated measurements of antiproton-proton annihilation into all-neutral final states using the Crystal Ball. The data in fact show that the Crystal Ball with its large angular acceptance and multi-photon capability would be an excellent detector for such an experiment. Only one other such experiment (the Crystal Barrel experiment at CERN/LEAR) has ever been …
Date: November 15, 1999
Creator: Allgower, C. & Peaslee, D.
Object Type: Report
System: The UNT Digital Library
Increased oil production and reserves from improved completion techniques in the Bluebell Field, Uinta Basin, Utah. Quarterly technical progress report, July 1, 1995--September 30, 1995 (open access)

Increased oil production and reserves from improved completion techniques in the Bluebell Field, Uinta Basin, Utah. Quarterly technical progress report, July 1, 1995--September 30, 1995

The objective of this project is to increase oil production and reserves in the Uinta Basin by demonstrating improved completion techniques. Low productivity of Uinta Basin wells is caused by gross production intervals of several thousand feet that contain perforated thief zones and water-bearing zones, and unperforated oil-bearing intervals. Geologic and engineering characterization and computer simulation of the Green River and Wasatch Formations in the Bluebell field will determine reservoir heterogeneities related to fractures and depositional trends. This will be followed by drilling and recompletion of several wells to demonstrate improved completion techniques based on the reservoir characterization. Transfer of the project results will be an ongoing component of the project.
Date: October 15, 1995
Creator: Allison, E. & Morgan, C. D.
Object Type: Report
System: The UNT Digital Library
Increased oil production and reserves utilizing secondary/tertiary recovery techniques on small reservoirs in the Paradox basin, Utah. Final technical progress report, October 1--December 31, 1995 (open access)

Increased oil production and reserves utilizing secondary/tertiary recovery techniques on small reservoirs in the Paradox basin, Utah. Final technical progress report, October 1--December 31, 1995

The primary objective of this project is to enhance domestic petroleum production by demonstration and technology transfer of an advanced oil recovery technology in the Paradox basin, southeastern Utah. If this project can demonstrate technical and economic feasibility, the technique can be applied to approximately 100 additional small fields in the Paradox basin alone, and result in increased recovery of 150 to 200 million barrels of oil. This project is designed to characterize five shallow-shelf carbonate reservoirs in the Pennsylvanian (Desmoinesian) Paradox Formation and choose the best candidate for a pilot demonstration project for either a waterflood or carbon dioxide-(CO{sub 2}) flood project. The field demonstration, monitoring of field performance, and associated validation activities will take place in the Paradox basin within the Navajo Nation. The results of this project will be transferred to industry and other researchers through a petroleum extension service, creation of digital databases for distribution, technical workshops and seminars, field trips, technical presentations at national and regional professional meeting, and publication in newsletters and various technical or trade journals. Five activities continued this quarter as part of the geological and reservoir characterization of carbonate mound buildups in the Paradox basin: (1) regional facies evaluation, (2) evaluation …
Date: January 15, 1996
Creator: Allison, M. L.
Object Type: Report
System: The UNT Digital Library
Dynamic Fiber Optic Sensors Under Intense Radioactive Environments (open access)

Dynamic Fiber Optic Sensors Under Intense Radioactive Environments

A liquid mercury target will be used as the neutron source for the proposed Spallation Neutron Source facility. This target is subjected to bombardment by short-pulse, high-energy proton beams. The intense thermal loads caused by interaction of the pulsed proton beam with the mercury create an enormous rate of temperature rise ({approximately}10{sup 7} K/s) during a very brief beam pulse ({approximately } 0.5 {micro}s). The resulting pressure waves in the mercury will interact with the walls of the mercury target and may lead to large stresses. To gain confidence in the mercury target design concept and to benchmark the computer design codes, we tested various electrical and optical sensors for measuring the transient strains on the walls of a mercury container and the pressures in the mercury. The sensors were attached on several sample mercury targets that were tested at various beam facilities: Oak Ridge Electron Linear Accelerator, Los Alamos Neutron Science Center-Weapons Neutron Research, and Brookhaven National Laboratory's Alternating Gradient Synchrotron. The effects of intense background radiation on measured signals for each sensor are described and discussed. Preliminary results of limited tests at these facilities indicate that the fiber optic sensors function well in this intense radiation environment, whereas …
Date: October 15, 1998
Creator: Allison, S. W.; Earl, D. D.; Haines, J. R. & Tsai, C. C.
Object Type: Article
System: The UNT Digital Library
The Slow:Fast substitution ratio reveals changing patterns of natural selection in gamma-proteobacterial genomes (open access)

The Slow:Fast substitution ratio reveals changing patterns of natural selection in gamma-proteobacterial genomes

Different microbial species are thought to occupy distinct ecological niches, subjecting each species to unique selective constraints, which may leave a recognizable signal in their genomes. Thus, it may be possible to extract insight into the genetic basis of ecological differences among lineages by identifying unusual patterns of substitutions in orthologous gene or protein sequences. We use the ratio of substitutions in slow versus fast-evolving sites (nucleotides in DNA, or amino acids in protein sequence) to quantify deviations from the typical pattern of selective constraint observed across bacterial lineages. We propose that elevated S:F in one branch (an excess of slow-site substitutions) can indicate a functionally-relevant change, due to either positive selection or relaxed evolutionary constraint. In a genome-wide comparative study of gamma-proteobacterial proteins, we find that cell-surface proteins involved with motility and secretion functions often have high S:F ratios, while information-processing genes do not. Change in evolutionary constraints in some species is evidenced by increased S:F ratios within functionally-related sets of genes (e.g., energy production in Pseudomonas fluorescens), while other species apparently evolve mostly by drift (e.g., uniformly elevated S:F across most genes in Buchnera spp.). Overall, S:F reveals several species-specific, protein-level changes with potential functional/ecological importance. As microbial …
Date: April 15, 2009
Creator: Alm, Eric & Shapiro, B. Jesse
Object Type: Article
System: The UNT Digital Library
Distributed H{sub 2} Supply for Fuel Cell Utility Vehicles Year 6 - Activity 3.5 - Development fo a National Center for Hydrogen Technology (open access)

Distributed H{sub 2} Supply for Fuel Cell Utility Vehicles Year 6 - Activity 3.5 - Development fo a National Center for Hydrogen Technology

The Energy & Environmental Research Center (EERC) has developed a high-pressure hydrogen production system that reforms a liquid organic feedstock and water at operating pressures up to 800 bar (~12,000 psig). The advantages of this system include the elimination of energy-intensive hydrogen compression, a smaller process footprint, and the elimination of gaseous or liquid hydrogen transport. This system could also potentially enable distributed hydrogen production from centralized coal. Processes have been investigated to gasify coal and then convert the syngas into alcohol or alkanes. These alcohols and alkanes could then be easily transported in bulk to distributed high-pressure water-reforming (HPWR)-based systems to deliver hydrogen economically. The intent of this activity was to utilize the EERC’s existing HPWR hydrogen production process, previously designed and constructed in a prior project phase, as a basis to improve operational and production performance of an existing demonstration unit. Parameters to be pursued included higher hydrogen delivery pressure, higher hydrogen production rates, and the ability to refill within a 5-minute time frame.
Date: April 15, 2012
Creator: Almlie, Jay
Object Type: Report
System: The UNT Digital Library
Container Refurbishment Cycle Time Reduction (CTR) Project (open access)

Container Refurbishment Cycle Time Reduction (CTR) Project

In mid-1999, a Cycle Time Reduction (CTR) project was initiated by senior management to improve the overall efficiency of the Container Refurbishment process. A cross-functional team was formed by the Industrial Engineering Services group within Product Certification Organization to evaluate the current process and to propose necessary changes for improvement. The CTR team efforts have resulted in increased productivity equaling approximately $450K per year. The effort also significantly reduced the wait time required necessary to start assembly work on the shop floor. Increasing daily production time and identifying delays were key team goals. Following is a brief summary of accomplishments: (A) Productivity Improvements: (1) Reduced Radcon survey time for empty containers: (i) 50% at 9720-3 (ii) 67% at 9204-2 and (iii) 100% at 9212; (2) Eliminated container inspections at 9720-3; (3) Reduced charged time (includes hands-on labor and support functions) per empty container by 25%; (4) Reduced cycle time to refurbish a container by 25%. (Dramatic wait time reduction -Assembly); (5) Reduced the time for 9212 to receive empty, refurbished containers by 67-80%; (6) Reduced the time for 9204-2E to receive empty, refurbished containers from 1 day to immediate; (7) Implemented software to track time charged per container for continuous …
Date: May 15, 2000
Creator: Aloi, Tim; Anthony, Perry; Blair, Tom; Forester, Celina; Hall, Ken; Hawk, Todd et al.
Object Type: Report
System: The UNT Digital Library
Effect of Boundary Conditions on a Non-Equilibrium Transient Marshak Wave Problem (open access)

Effect of Boundary Conditions on a Non-Equilibrium Transient Marshak Wave Problem

Transient processes in radiative transfer have recently become of interest in the modeling of astrophysical phenomena, particularly with regard to the brightness of novae, supernovae, and perhaps even galactic clouds adjacent to quasars. Analytic solutions to a particular class of Marshak wave problems are presented with and without the Marshak (Milne) boundary condition. The choice of boundary condition can have a decisive effect on the coupling of radiative energy to the material energy in the vicinity of a material boundary. The analytic solution obtained can be useful as a tool for calibrating numerical calculation techniques.
Date: January 15, 1979
Creator: Alonso, C. T. & Pomraning, G. C.
Object Type: Article
System: The UNT Digital Library
Multiscale modeling of radiation effects in fcc and bcc metals (open access)

Multiscale modeling of radiation effects in fcc and bcc metals

The prospect of using computer simulations to calculate radiation-induced defect production and its influence on microstructure evolution and mechanical property changes during prolonged irradiation of nuclear materials has been a beckoning, yet elusive goal for many years. However, the enormous progress achieved in computational physics for calculating reliable, yet tractable interatomic potentials, coupled with vast improvements in computational power have brought this hope to near reality. In order to develop modeling and simulation tools for predicting the irradiation response of nuclear structural materials, models must be implemented and tested across all relevant length and time scales. We discuss the development and implementation of a modeling methodology that consists of the linkage and hierarchical use of ab initio electronic structure calculations, molecular dynamics (MD) simulations, and kinetic Monte Carlo (KMC) simulations. This methodology can describe length and time scales from nanometers to hundreds of microns and from picoseconds to years, respectively. The ideas are demonstrated in two applications. First, we describe simulations that describe the irradiation and subsequent isochronal annealing of Pb, a low melting point fcc metal, and compare the results to experiments. Second, we show how these methods can be used to investigate damage production and freely migrating defect …
Date: July 15, 1999
Creator: Alonso, E; Caturla, M; Diaz de la Rubia, T; Felter, T; Fluss, M; Perlado, J et al.
Object Type: Article
System: The UNT Digital Library