8 GeV beam line optics optimization for the rapid antiproton transfers at Fermilab (open access)

8 GeV beam line optics optimization for the rapid antiproton transfers at Fermilab

Tevatron Run-II upgrade requires a significant increase of the efficiency and speed of the antiproton transfers from the Accumulator to the Recycler. The goal for the total transfer time is challenging a reduction from 1 hour down to a few minutes. Here we discuss the beam line optics aspects of this project. Results of lattice measurements and optimization are analyzed in terms of transport efficiency and stability.
Date: February 1, 2007
Creator: Nagaslaev, V.; Lebedev, V.; Morgan, J. & Vander Meulen, D.
System: The UNT Digital Library
12th Workshop on Crystalline Silicon Solar Cell Materials and Processes: Summary Discussion Sessions (open access)

12th Workshop on Crystalline Silicon Solar Cell Materials and Processes: Summary Discussion Sessions

This report is a summary of the discussion sessions of the 12th Workshop on Crystalline Silicon Solar Cells and Processes. The theme of the workshop was"Fundamental R&D in c-Si: Enabling Progress in Solar-Electric Technology." This theme was chosen to reflect a concern that the current expansion in the PV energy production may redirect basic research efforts to production-oriented issues. The PV industry is installing added production capacity and new production lines that include the latest technologies. Once the technologies are selected, it is difficult to make changes. Consequently, a large expansion can stagnate the technologies and diminish interest in fundamental research. To prevent the fundamental R&D program from being overwhelmed by the desire to address immediate engineering issues, there is a need to establish topics of fundamental nature that can be pursued by the universities and the research institutions. Hence, one of the objectives of the workshop was to identify such areas for fundamental research.
Date: February 1, 2003
Creator: Sopori, B.; Swanson, D.; Sinton, R. & Tan, T.
System: The UNT Digital Library
2007 Renewable Energy: Solar Fuels Gordon Research Conference - January 21-26 (open access)

2007 Renewable Energy: Solar Fuels Gordon Research Conference - January 21-26

This Gordon Research Conference seeks to brings together chemists, physicists, materials scientists and biologists to address perhaps the outstanding technical problem of the 21st Century - the efficient, and ultimately economical, storage of energy from carbon-neutral sources. Such an advance would deliver a renewable, environmentally benign energy source for the future. A great technological challenge facing our global future is energy. The generation of energy, the security of its supply, and the environmental consequences of its use are among the world's foremost geopolitical concerns. Fossil fuels - coal, natural gas, and petroleum - supply approximately 90% of the energy consumed today by industrialized nations. An increase in energy supply is vitally needed to bring electric power to the 25% of the world's population that lacks it, to support the industrialization of developing nations, and to sustain economic growth in developed countries. On the geopolitical front, insuring an adequate energy supply is a major security issue for the world, and its importance will grow in proportion to the singular dependence on oil as a primary energy source. Yet, the current approach to energy supply, that of increased fossil fuel exploration coupled with energy conservation, is not scaleable to meet future demands. …
Date: February 1, 2008
Creator: Nocera, Daniel G.
System: The UNT Digital Library
Acquisition and processing of multiparametric information from apixelmatrix (open access)

Acquisition and processing of multiparametric information from apixelmatrix

This paper addresses the design of a system intended to readout multiparametric information from a matrix of pixels. The system presented here acquires the charge associated with the signal and provides a timing information from each pixel. Although it lends itself to a broad range of time-correlated imaging situations involving any kind of pixel matrices, the design constraints assumed here are particularly tailored to the application with pixels that sense the output charge distribution from a Micro Channel Plate (MCP). The combination of a microchannel plate and a pixel matrix is an extremely versatile detector and the readout system must be able to fully exploit the intrinsically high position resolution and time accuracy featured by the MCP. The behavior of the readout system described in this paper is based upon advanced concepts to meet the above application requirements and is believed to provide a significant functional improvement over the conventional pixel systems.
Date: February 1, 2001
Creator: Manfredi, P.F.; Millaud, J.E. & Sushkov, V.V.
System: The UNT Digital Library
Action-Oriented Benchmarking: Using the CEUS Database to Benchmark Commercial Buildings in California (open access)

Action-Oriented Benchmarking: Using the CEUS Database to Benchmark Commercial Buildings in California

The 2006 Commercial End Use Survey (CEUS) database developed by the California Energy Commission is a far richer source of energy end-use data for non-residential buildings than has previously been available and opens the possibility of creating new and more powerful energy benchmarking processes and tools. In this article--Part 2 of a two-part series--we describe the methodology and selected results from an action-oriented benchmarking approach using the new CEUS database. This approach goes beyond whole-building energy benchmarking to more advanced end-use and component-level benchmarking that enables users to identify and prioritize specific energy efficiency opportunities - an improvement on benchmarking tools typically in use today.
Date: February 1, 2008
Creator: Mathew, Paul; Mills, Evan; Bourassa, Norman & Brook, Martha
System: The UNT Digital Library
Adaptive optics ophthalmologic systems using dual deformable mirrors (open access)

Adaptive optics ophthalmologic systems using dual deformable mirrors

Adaptive Optics (AO) have been increasingly combined with a variety of ophthalmic instruments over the last decade to provide cellular-level, in-vivo images of the eye. The use of MEMS deformable mirrors in these instruments has recently been demonstrated to reduce system size and cost while improving performance. However, currently available MEMS mirrors lack the required range of motion for correcting large ocular aberrations, such as defocus and astigmatism. In order to address this problem, we have developed an AO system architecture that uses two deformable mirrors, in a woofer/tweeter arrangement, with a bimorph mirror as the woofer and a MEMS mirror as the tweeter. This setup provides several advantages, including extended aberration correction range, due to the large stroke of the bimorph mirror, high order aberration correction using the MEMS mirror, and additionally, the ability to ''focus'' through the retina. This AO system architecture is currently being used in four instruments, including an Optical Coherence Tomography (OCT) system and a retinal flood-illuminated imaging system at the UC Davis Medical Center, a Scanning Laser Ophthalmoscope (SLO) at the Doheny Eye Institute, and an OCT system at Indiana University. The design, operation and evaluation of this type of AO system architecture will …
Date: February 1, 2007
Creator: Jones, S.; Olivier, S.; Chen, D.; Sadda, S.; Joeres, S.; Zawadzki, R. et al.
System: The UNT Digital Library
Advanced Assay Systems for Radionuclide Contamination in Soils (open access)

Advanced Assay Systems for Radionuclide Contamination in Soils

Through the support of the Department of Energy (DOE) Office of Environmental Management (EM) Technical Assistance Program, the Idaho National Laboratory (INL) has developed and deployed a suite of systems that rapidly scan, characterize, and analyze surface soil contamination. The INL systems integrate detector systems with data acquisition and synthesis software and with global positioning technology to provide a real-time, user-friendly field deployable turn-key system. INL real-time systems are designed to characterize surface soil contamination using methodologies set forth in the Multi-Agency Radiation Surveys and Site Investigation Manual (MARSSIM). MARSSIM provides guidance for planning, implementing, and evaluating environmental and facility radiological surveys conducted to demonstrate compliance with a dose or risk-based regulation and provides real-time information that is immediately available to field technicians and project management personnel. This paper discusses the history of the development of these systems and describes some of the more recent examples and their applications.
Date: February 1, 2008
Creator: Giles, J. R.; Roybal, L. G.; Carpenter, M. V.; Oertel, C. P. & Roach, J. A.
System: The UNT Digital Library
Advanced Modeling of Cold Crucible Induction Melting for Process Control and Optimization (open access)

Advanced Modeling of Cold Crucible Induction Melting for Process Control and Optimization

The Idaho National Laboratory (INL) and the St. Petersburg Electrotechnical University “LETI” (ETU) have collaborated on development and validation of an advanced numerical model of the cold crucible induction melting (CCIM) process. This work was conducted in support of the Department of Energy (DOE) Office of Environmental Management Technology and Engineering (EM-20) International Program. The model predicts quasi-steady state temperature distributions, convection cell configurations, and flow field velocities for a fully established melt of low conductivity non-magnetic materials at high frequency operations. The INL/ETU ANSYS© finite element model is unique in that it has been developed specifically for processing borosilicate glass (BSG) and other glass melts. Specifically, it accounts for the temperature dependency of key material properties, some of which change by orders of magnitude within the temperature ranges experienced (temperature differences of 500oC are common) in CCIM processing of glass, including density, viscosity, thermal conductivity, specific heat, and electrical resistivity. These values, and their responses to temperature changes, are keys to understanding the melt characteristics. Because the model has been validated, it provides the capability to conduct parametric studies to understand operational sensitivities and geometry effects. Additionally, the model can be used to indirectly determine difficult to measure material …
Date: February 1, 2008
Creator: Roach, J. A.; Lopukh, D. B.; Martynov, A. P.; Polevodov, B. S. & Chepluk, S. I.
System: The UNT Digital Library
Advanced Polymer Technology for Containing and Immobilizing Strontium-90 in the Subsurface - 8361 (open access)

Advanced Polymer Technology for Containing and Immobilizing Strontium-90 in the Subsurface - 8361

Many Department of Energy (DOE) sites, including Idaho and Hanford, have heavy metals and/or radionuclides (e.g. strontium-90) present that are strongly adsorbed in the vadose zone, but which nevertheless are propagating toward the water table. A key challenge for immobilization of these contaminants is bringing the chosen amendment or remediation technology into contact with the contaminated porous medium, while ensuring that contaminated water and colloids do not escape. This is particularly challenging when the subsurface geology is complex and highly heterogeneous, as is the case at many DOE sites. The Idaho National Laboratory (INL) in collaboration with the University of Texas at Austin (UT) has conducted research sponsored through the DOE Office of Environmental Management (EM) Advanced Remediation Technologies Phase I program that successfully demonstrated application of a novel, pH-triggered advanced polymer for creating a physical barrier that prevents heavy metals and radionuclides in vadose zone soil and soil-pore water from migrating to the groundwater. The focus of this paper is on the column and sandbox experiments conducted by researchers at the Idaho National Laboratory in support of the Phase I program objectives. Proof of these concepts provides a technology basis for confining or isolating a volume of contaminated groundwater, …
Date: February 1, 2008
Creator: Baker, K.; Heath, G.; Scott, C.; Schafer, A.; Bryant, S.; Sharma, M. et al.
System: The UNT Digital Library
ADVANCED TECHNOLOGIES FOR THE SIMULTANEOUS SEPARATION OF CESIUM AND STRONTIUM FROM SPENT NUCLEAR FUEL (open access)

ADVANCED TECHNOLOGIES FOR THE SIMULTANEOUS SEPARATION OF CESIUM AND STRONTIUM FROM SPENT NUCLEAR FUEL

Two new solvent extraction technologies have been recently developed to simultaneously separate cesium and strontium from spent nuclear fuel, following dissolution in nitric acid. The first process utilizes a solvent consisting of chlorinated cobalt dicarbollide and polyethylene glycol extractants in a phenyltrifluoromethyl sulfone diluent. Recent improvements to the process include development of a new, non-nitroaromatic diluent and development of new stripping reagents, including a regenerable strip reagent that can be recovered and recycled. This new strip reagent reduces product volume by a factor of 20, over the baseline process. Countercurrent flowsheet tests on simulated spent nuclear fuel feed streams have been performed with both cesium and strontium removal efficiencies of greater than 99 %. The second process developed to simultaneously separate cesium and strontium from spent nuclear fuel is based on two highly-specific extractants: 4',4',(5')-Di-(t-butyldicyclo-hexano)-18-crown-6 (DtBuCH18C6) and Calix[4]arene-bis-(tert-octylbenzo-crown-6) (BOBCalixC6). The DtBuCH18C6 extractant is selective for strontium and the BOBCalixC6 extractant is selective for cesium. A solvent composition has been developed that enables both elements to be removed together and, in fact, a synergistic effect was observed with strontium distributions in the combined solvent that are much higher that in the strontium extraction (SREX) process. Initial laboratory test results of the …
Date: February 1, 2005
Creator: Law, Jack D.; Todd, Terry A.; Herbst, R. Scott; Meikrantz, David H.; Peterman, Dean R.; Riddle, Catherine L. et al.
System: The UNT Digital Library
Advanced Vadose Zone Simulations Using TOUGH (open access)

Advanced Vadose Zone Simulations Using TOUGH

The vadose zone can be characterized as a complex subsurfacesystem in which intricate physical and biogeochemical processes occur inresponse to a variety of natural forcings and human activities. Thismakes it difficult to describe, understand, and predict the behavior ofthis specific subsurface system. The TOUGH nonisothermal multiphase flowsimulators are well-suited to perform advanced vadose zone studies. Theconceptual models underlying the TOUGH simulators are capable ofrepresenting features specific to the vadose zone, and of addressing avariety of coupled phenomena. Moreover, the simulators are integratedinto software tools that enable advanced data analysis, optimization, andsystem-level modeling. We discuss fundamental and computationalchallenges in simulating vadose zone processes, review recent advances inmodeling such systems, and demonstrate some capabilities of the TOUGHsuite of codes using illustrative examples.
Date: February 1, 2007
Creator: Finsterle, S.; Doughty, C.; Kowalsky, M.B.; Moridis, G.J.; Pan,L.; Xu, T. et al.
System: The UNT Digital Library
AFM-Based Microelectrical Characterization of Grain Boundaries in Cu(In,Ga)Se2 Thin Films (open access)

AFM-Based Microelectrical Characterization of Grain Boundaries in Cu(In,Ga)Se2 Thin Films

We report on a direct measurement of two-dimensional potential distribution on the surface of Cu(In,Ga)Se2 thin films using a nanoscale electrical characterization of scanning Kelvin probe microscopy both in air and in ultra-high vacuum. The potential measurement reveals a higher surface potential or a smaller work function on grain boundaries (GBs) of the film than on the grain surfaces. This demonstrates the existence of a local built-in potential on GBs, and the GB is positively charged. The role of the built-in potential in device performance was further examined and found to be positive, by tuning Ga content or bandgap of the film. With increasing Ga content, the potential drops sharply in a Ga range of 28%-38%. Comparing the change in the built-in potential to the theoretical and experimental photoconversion efficiencies, we conclude that the potential plays a significant role in the device conversion efficiency of NREL's three-stage Cu(In,Ga)Se2 device.
Date: February 1, 2005
Creator: Jiang, C. S.; Noufi, R.; Ramanathan, K.; AbuShama, J. A.; Moutinho, H. R. & Al-Jassim, M. M.
System: The UNT Digital Library
AFREET: HUMAN-INSPIRED SPATIO-SPECTRAL FEATURE CONSTRUCTION FOR IMAGE CLASSIFICATION WITH SUPPORT VECTOR MACHINES (open access)

AFREET: HUMAN-INSPIRED SPATIO-SPECTRAL FEATURE CONSTRUCTION FOR IMAGE CLASSIFICATION WITH SUPPORT VECTOR MACHINES

The authors examine the task of pixel-by-pixel classification of the multispectral and grayscale images typically found in remote-sensing and medical applications. Simple machine learning techniques have long been applied to remote-sensed image classification, but almost always using purely spectral information about each pixel. Humans can often outperform these systems, and make extensive use of spatial context to make classification decisions. They present AFREET: an SVM-based learning system which attempts to automatically construct and refine spatio-spectral features in a somewhat human-inspired fashion. Comparisons with traditionally used machine learning techniques show that AFREET achieves significantly higher performance. The use of spatial context is particularly useful for medical imagery, where multispectral images are still rare.
Date: February 1, 2001
Creator: PERKINS, S. & HARVEY, N.
System: The UNT Digital Library
Alternative Flowsheets for the Sulfur-Iodine Thermochemical Hydrogen Cycle (open access)

Alternative Flowsheets for the Sulfur-Iodine Thermochemical Hydrogen Cycle

OAK-B135 A hydrogen economy will need significant new sources of hydrogen. Unless large-scale carbon sequestration can be economically implemented, use of hydrogen reduces greenhouse gases only if the hydrogen is produced with non-fossil energy sources. Nuclear energy is one of the limited options available. One of the promising approaches to produce large quantities of hydrogen from nuclear energy efficiently is the Sulfur-Iodine (S-I) thermochemical water-splitting cycle, driven by high temperature heat from a helium Gas-Cooled Reactor. They have completed a study of nuclear-driven thermochemical water-splitting processes. The final task of this study was the development of a flowsheet for a prototype S-I production plant. An important element of this effort was the evaluation of alternative flowsheets and selection of the reference design.
Date: February 1, 2003
Creator: Brown, L. C.; Lentsch, R. D.; Besenbruch, G. E.; Schultz, K. R. & Funk, J. E.
System: The UNT Digital Library
Alternative Site Technology Deployment-Monitoring System for the U-3ax/bl Disposal Unit at the Nevada Test Site (open access)

Alternative Site Technology Deployment-Monitoring System for the U-3ax/bl Disposal Unit at the Nevada Test Site

In December 2000, a performance monitoring facility was constructed adjacent to the U-3ax/bl mixed waste disposal unit at the Nevada Test Site (NTS). Recent studies conducted in the arid southwestern United States suggest that a vegetated monolayer evapotranspiration (ET) closure cover may be more effective at isolating waste than traditional Resource Conservation and Recovery Act (RCRA) multi-layered designs. The monitoring system deployed next to the U-3ax/bl disposal unit consists of eight drainage lysimeters with three surface treatments: two are left bare; two are revegetated with native species; two are being allowed to revegetate with invader species; and two are reserved for future studies. Soil used in each lysimeter is native alluvium taken from the same location as the soil used for the cover material on U-3ax/bl. The lysimeters were constructed so that any drainage to the bottom can be collected and measured. To provide a detailed evaluation of the cover performance, an ar ray of 16 sensors was installed in each lysimeter to measure soil water content, soil water potential, and soil temperature. Revegetation of the U-3ax/bl closure cover establishes a stable plant community that maximizes water loss through transpiration while at the same time, reduces water and wind erosion …
Date: February 1, 2001
Creator: Dixon, J. M.; Levitt, D. G. & Rawlinson, S. E.
System: The UNT Digital Library
Ammonia Solubility in High Concentration Salt Solutions (open access)

Ammonia Solubility in High Concentration Salt Solutions

Solubility data for ammonia in water and various dilute solutions are abundant in the literature. However, there is a noticeable lack of ammonia solubility data for high salt, basic solutions of various mixtures of salts including those found in many of the Hanford Washington underground waste tanks. As a result, models based on solubility data for dilute salt solutions have been used to extrapolate to high salt solutions. These significant extrapolations need to be checked against actual laboratory data. Some indirect vapor measurements have been made. A more direct approach is to determine the ratio of solubility of ammonia in water to its solubility in high salt solutions. In various experiments, pairs of solutions, one of which is water and the other a high salt solution, are allowed to come to equilibrium with a common ammonia vapor pressure. The ratio of concentrations of ammonia in the two solutions is equal to the ratio of the respective ammonia solubilities (Henry's Law constants) at a given temperature. This information can then be used to refine the models that predict vapor space compositions of ammonia. Ammonia at Hanford is of concern because of its toxicity in the environment and its contribution to the …
Date: February 1, 2000
Creator: HEDENGREN, D.C.
System: The UNT Digital Library
Analysis and Simulation of the Structure of Nanoparticles That Undergo a Surface-Driven Structural Transformation (open access)

Analysis and Simulation of the Structure of Nanoparticles That Undergo a Surface-Driven Structural Transformation

This report addresses the analysis and simulation of the structure of nanoparticles that undergo a surface-driven structural transformation.
Date: February 1, 2004
Creator: Gilbert, Benjamin; Zhang, Hengzhong; Huang, Feng; Ren, Yang; Haskel, Daniel; Lang, J.C. et al.
System: The UNT Digital Library
Analysis of Depletion-Region Collection in GaInNAs Solar Cells (open access)

Analysis of Depletion-Region Collection in GaInNAs Solar Cells

We provide qualitative insight into depletion-region collection in GaInNAs cells to (1) understand the effect of diffusion length L on the QE; and (2) describe the magnitude of L required to get adequate current from the cell. We use Wolf's equations for the QE including a drift field E, and model E as being equal to the junction built-in voltage distributed uniformly across the depletion region. This allows us to calculate the QE as a function of L and depletion width WD. We show that if L is sufficiently small, increasing WD can actually decrease the QE. To determine how long L needs to be in a practical GaInNAs junction, we calculate from the QE the short-circuit current density as a function of WD and L. This allows us to estimate that Lambipolar needs to be greater than roughly 1 {micro}m in order to obtain enough photocurrent for the 4-junction application, giving guidance to the experimental effort to develop such cells.
Date: February 1, 2005
Creator: Friedman, D. J.; Ptak, A. J.; Kurtz, S. R. & Geisz, J. F.
System: The UNT Digital Library
THE ANALYTICAL MONTE CARLO METHOD FOR RADIATION TRANSPORT CALCULATIONS (open access)

THE ANALYTICAL MONTE CARLO METHOD FOR RADIATION TRANSPORT CALCULATIONS

None
Date: February 1, 2001
Creator: MARTIN, W. & BROWN, F.
System: The UNT Digital Library
Angular Signatures of Dark Matter in the Diffuse Gamma Ray Spectrum (open access)

Angular Signatures of Dark Matter in the Diffuse Gamma Ray Spectrum

Dark matter annihilating in our Galaxy's halo and elsewhere in the universe is expected to generate a diffuse flux of gamma rays, potentially observable with next generation satellite-based experiments, such as GLAST. In this article, we study the signatures of dark matter in the angular distribution of this radiation. Pertaining to the extragalactic contribution, we discuss the effect of the motion of the solar system with respect to the cosmological rest frame, and anisotropies due to the structure of our local universe. For the gamma ray flux from dark matter in our own Galactic halo, we discuss the effects of the offset position of the solar system, the Compton-Getting effect, the asphericity of the Milky Way halo, and the signatures of nearby substructure. We explore the prospects for the detection of these features by the GLAST satellite and find that, if {approx} 10% or more of the diffuse gamma ray background observed by EGRET is the result of dark matter annihilations, then GLAST should be sensitive to anisotropies down to the 0.1% level. Such precision would be sufficient to detect many, if not all, of the signatures discussed in this paper.
Date: February 1, 2007
Creator: Hooper, Dan & Serpico, Pasquale D.
System: The UNT Digital Library
Anomalies in the Applied Magnetic Fields on Diii-D and Their Implications for the Understanding of Stability Experiments (open access)

Anomalies in the Applied Magnetic Fields on Diii-D and Their Implications for the Understanding of Stability Experiments

Small non-axisymmetric magnetic fields are known to cause serious loss of stability in tokamaks leading to loss of confinement and abrupt termination of plasma current (disruptions). The best known examples are the locked mode and the resistive wall mode. Understanding of the underlying field anomalies (departures in the hardware-related fields from ideal toroidal and poloidal fields on a single axis) and the interaction of the plasma with them is crucial to tokamak development. Results of both locked mode experiments and resistive wall mode experiments done in DIII-D tokamak plasmas have been interpreted to indicate the presence of a significant anomalous field. New measurements of the magnetic field anomalies of the hardware systems have been made on DIII-D. The measured field anomalies due to the plasma shaping coils in DIII-D are smaller than previously reported. Additional evaluations of systematic errors have been made. New measurements of the anomalous fields of the ohmic heating and toroidal coils have been added. Such detailed in situ measurements of the fields of a tokamak are unique. The anomalous fields from all of the coils are one third of the values indicated from the stability experiments. These results indicate limitations in the understanding of the interaction …
Date: February 1, 2003
Creator: Luxon, J.L.; Schaffer, M.J.; Jackson, G.L.; Leuer, J.A.; Nagy, A.; Scoville, J.T. et al.
System: The UNT Digital Library
Anthocyanidin reductases from Medicago truncatula and Arabidopsis thaliana (open access)

Anthocyanidin reductases from Medicago truncatula and Arabidopsis thaliana

Article on anthocyanidin reductases from Medicago truncatula and Arabidopsis thaliana.
Date: February 1, 2004
Creator: Xie, De-Yu; Sharma, Shashi B. & Dixon, R. A.
System: The UNT Digital Library
Applicability of a Bonner Shere technique for pulsed neutron in 120 GeV proton facility (open access)

Applicability of a Bonner Shere technique for pulsed neutron in 120 GeV proton facility

The data on neutron spectra and intensity behind shielding are important for radiation safety design of high-energy accelerators since neutrons are capable of penetrating thick shielding and activating materials. Corresponding particle transport codes--that involve physics models of neutron and other particle production, transportation, and interaction--have been developed and used world-wide [1-8]. The results of these codes have been ensured through plenty of comparisons with experimental results taken in simple geometries. For neutron generation and transport, several related experiments have been performed to measure neutron spectra, attenuation length and reaction rates behind shielding walls of various thicknesses and materials in energy range up to several hundred of MeV [9-11]. The data have been used to benchmark--and modify if needed--the simulation modes and parameters in the codes, as well as the reference data for radiation safety design. To obtain such kind of data above several hundred of MeV, Japan-Fermi National Accelerator Laboratory (FNAL) collaboration for shielding experiments has been started in 2007, based on suggestion from the specialist meeting of shielding, Shielding Aspects of Target, Irradiation Facilities (SATIF), because of very limited data available in high-energy region (see, for example, [12]). As a part of this shielding experiment, a set of Bonner …
Date: February 1, 2008
Creator: Sanami, T.; Hagiwara, M.; Iwase, H.; Iwamoto, Y.; Sakamoto, Y.; Nakashima, H. et al.
System: The UNT Digital Library
Application of Gamma code coupled with turbomachinery models for high temperature gas-cooled reactors (open access)

Application of Gamma code coupled with turbomachinery models for high temperature gas-cooled reactors

The very high-temperature gas-cooled reactor (VHTR) is envisioned as a single- or dual-purpose reactor for electricity and hydrogen generation. The concept has average coolant temperatures above 9000C and operational fuel temperatures above 12500C. The concept provides the potential for increased energy conversion efficiency and for high-temperature process heat application in addition to power generation. While all the High Temperature Gas Cooled Reactor (HTGR) concepts have sufficiently high temperature to support process heat applications, such as coal gasification, desalination or cogenerative processes, the VHTR’s higher temperatures allow broader applications, including thermochemical hydrogen production. However, the very high temperatures of this reactor concept can be detrimental to safety if a loss-ofcoolant accident (LOCA) occurs. Following the loss of coolant through the break and coolant depressurization, air will enter the core through the break by molecular diffusion and ultimately by natural convection, leading to oxidation of the in-core graphite structure and fuel. The oxidation will accelerate heatup of the reactor core and the release of a toxic gas, CO, and fission products. Thus, without any effective countermeasures, a pipe break may lead to significant fuel damage and fission product release. Prior to the start of this Korean/United States collaboration, no computer codes were …
Date: February 1, 2008
Creator: Oh, Chang
System: The UNT Digital Library