ZPR-3 Assembly 12 : A Cylindrical Assembly of Highly Enriched Uranium, Depleted Uranium and Graphite With an Average {Sup 235}U Enrichment of 21 Atom %. (open access)

ZPR-3 Assembly 12 : A Cylindrical Assembly of Highly Enriched Uranium, Depleted Uranium and Graphite With an Average {Sup 235}U Enrichment of 21 Atom %.

Over a period of 30 years, more than a hundred Zero Power Reactor (ZPR) critical assemblies were constructed at Argonne National Laboratory. The ZPR facilities, ZPR-3, ZPR-6, ZPR-9 and ZPPR, were all fast critical assembly facilities. The ZPR critical assemblies were constructed to support fast reactor development, but data from some of these assemblies are also well suited for nuclear data validation and to form the basis for criticality safety benchmarks. A number of the Argonne ZPR/ZPPR critical assemblies have been evaluated as ICSBEP and IRPhEP benchmarks. Of the three classes of ZPR assemblies, engineering mockups, engineering benchmarks and physics benchmarks, the last group tends to be most useful for criticality safety. Because physics benchmarks were designed to test fast reactor physics data and methods, they were as simple as possible in geometry and composition. The principal fissile species was {sup 235}U or {sup 239}Pu. Fuel enrichments ranged from 9% to 95%. Often there were only one or two main core diluent materials, such as aluminum, graphite, iron, sodium or stainless steel. The cores were reflected (and insulated from room return effects) by one or two layers of materials such as depleted uranium, lead or stainless steel. Despite their more …
Date: September 30, 2010
Creator: Lell, R. M.; McKnight, R. D.; Perel, R. L.; Wagschal, J. J.; Division, Nuclear Engineering & Physics, Racah Inst. of
Object Type: Report
System: The UNT Digital Library
A Testbed of Parallel Kernels for Computer Science Research (open access)

A Testbed of Parallel Kernels for Computer Science Research

For several decades, computer scientists have sought guidance on how to evolve architectures, languages, and programming models for optimal performance, efficiency, and productivity. Unfortunately, this guidance is most often taken from the existing software/hardware ecosystem. Architects attempt to provide micro-architectural solutions to improve performance on fixed binaries. Researchers tweak compilers to improve code generation for existing architectures and implementations, and they may invent new programming models for fixed processor and memory architectures and computational algorithms. In today's rapidly evolving world of on-chip parallelism, these isolated and iterative improvements to performance may miss superior solutions in the same way gradient descent optimization techniques may get stuck in local minima. In an initial study, we have developed an alternate approach that, rather than starting with an existing hardware/software solution laced with hidden assumptions, defines the computational problems of interest and invites architects, researchers and programmers to implement novel hardware/ software co-designed solutions. Our work builds on the previous ideas of computational dwarfs, motifs, and parallel patterns by selecting a representative set of essential problems for which we provide: An algorithmic description; scalable problem definition; illustrative reference implementations; verification schemes. For simplicity, we focus initially on the computational problems of interest to the …
Date: April 30, 2010
Creator: Bailey, David; Demmel, James; Ibrahim, Khaled; Kaiser, Alex; Koniges, Alice; Madduri, Kamesh et al.
Object Type: Report
System: The UNT Digital Library
Fiber-Optic Defect and Damage Locator System for Wind Turbine Blades (open access)

Fiber-Optic Defect and Damage Locator System for Wind Turbine Blades

IFOS in collaboration with Auburn University demonstrated the feasibility of a Fiber Bragg Grating (FBG) integrated sensor system capable of providing real time in-situ defect detection, localization and quantification of damage. In addition, the system is capable of validating wind turbine blade structural models, using recent advances in non-contact, non-destructive dynamic testing of composite structures. This new generation method makes it possible to analyze wind turbine blades not only non-destructively, but also without physically contacting or implanting intrusive electrical elements and transducers into the structure. Phase I successfully demonstrated the feasibility of the technology with the construction of a 1.5 kHz sensor interrogator and preliminary instrumentation and testing of both composite material coupons and a wind turbine blade.
Date: October 30, 2010
Creator: Sotoudeh, Dr. Vahid; Black, Dr. Richard J.; Moslehi, Dr. Behzad & Plavsic, Mr. Aleks
Object Type: Report
System: The UNT Digital Library
Cause of a Multi-Species Radioiodine Plume That Is Increasing in Concentration (open access)

Cause of a Multi-Species Radioiodine Plume That Is Increasing in Concentration

Field and laboratory studies were carried out to understand the cause for steady increases in {sup 129}I concentrations emanating from radiological seepage basins located on the Savannah River Site. The basins were closed in 1988 by adding limestone and blast furnace slag and then capping with a RCRA low permeability engineered cover. Groundwater {sup 129}I concentrations in a well near the seepage basin in 1993 were 200 pCi L{sup -1} and are presently between 400 and 1000 pCi L{sup -1}. Iodine speciation in the plume was not uniform. Near the source, the iodine was comprised of 86% iodide, 2% iodate, and 12% organo-iodine (total activity = 178 pCi L{sup -1}). Whereas, groundwater iodine speciation 365 m down stream (25 m up stream from a wetland) was 0% iodide, 93% iodate, and 7% organo iodine. Batch desorption studies demonstrated that high concentrations of {sup 129}I could be incrementally desorbed from an archived seepage basin sediment sample by raising the pH. Batch sorption studies showed that iodate, IO{sub 3}{sup -}, sorbed more strongly than iodide, I{sup -}, to a subsurface clayey sediment, but equally well as iodide to a subsurface sandy sediment and a wetland sediment. Placing an organic-rich wetland sediment, but …
Date: September 30, 2010
Creator: Kaplan, D.
Object Type: Article
System: The UNT Digital Library
Improvements In Ethanologenic Escherichia Coli and Klebsiella Oxytoca (open access)

Improvements In Ethanologenic Escherichia Coli and Klebsiella Oxytoca

The current Verenium cellulosic ethanol process is based on the dilute-acid pretreatment of a biomass feedstock, followed by a two-stage fermentation of the pentose sugar-containing hydrolysate by a genetically modified ethanologenic Escherichia coli strain and a separate simultaneous saccharification-fermentation (SSF) of the cellulosic fraction by a genetically modified ethanologenic Klebsiella oxytoca strain and a fungal enzyme cocktail. In order to reduce unit operations and produce a fermentation beer with higher ethanol concentrations to reduce distillation costs, we have proposed to develop a simultaneous saccharification co-fermentation (SScF) process, where the fermentation of the pentose-containing hydrolysate and cellulosic fraction occurs within the same fermentation vessel. In order to accomplish this goal, improvements in the ethanologens must be made to address a number of issues that arise, including improved hydrolysate tolerance, co-fermentation of the pentose and hexose sugars and increased ethanol tolerance. Using a variety of approaches, including transcriptomics, strain adaptation, metagenomics and directed evolution, this work describes the efforts of a team of scientists from Verenium, University of Florida, Massachusetts Institute of Technology and Genomatica to improve the E. coli and K. oxytoca ethanologens to meet these requirements.
Date: September 30, 2010
Creator: Nunn, Dr. David
Object Type: Report
System: The UNT Digital Library
Photo-Induced Spin-State Conversion in Solvated Transition Metal Complexes Probed via Time-Resolved Soft X-ray Spectroscopy (open access)

Photo-Induced Spin-State Conversion in Solvated Transition Metal Complexes Probed via Time-Resolved Soft X-ray Spectroscopy

Solution-phase photoinduced low-spin to high-spin conversion in the FeII polypyridyl complex [Fe(tren(py)3)]2+ (where tren(py)3 is tris(2-pyridylmethyliminoethyl)amine) has been studied via picosecond soft X-ray spectroscopy. Following 1A1 --> 1MLCT (metal-to-ligand charge transfer) excitation at 560 nm, changes in the iron L2- and L3-edges were observed concomitant with formation of the transient high-spin 5T2 state. Charge-transfer multiplet calculations coupled with data acquired on low-spin and high-spin model complexes revealed a reduction in ligand field splitting of 1 eV in the high-spin state relative to the singlet ground state. A significant reduction in orbital overlap between the central Fe-3d and the ligand N-2p orbitals was directly observed, consistent with the expected ca. 0.2 Angstrom increase in Fe-N bond length upon formation of the high-spin state. The overall occupancy of the Fe-3d orbitals remains constant upon spin crossover, suggesting that the reduction in sigma-donation is compensated by significant attenuation of pi-back-bonding in the metal-ligand interactions. These results demonstrate the feasibility and unique potential of time-resolved soft X-ray absorption spectroscopy to study ultrafast reactions in the liquid phase by directly probing the valence orbitals of first-row metals as well as lighter elements during the course of photochemical transformations.
Date: April 30, 2010
Creator: Huse, Nils; Kim, Tae Kyu; Jamula, Lindsey; McCusker, James K.; de Groot, Frank M. F. & Schoenlein, Robert W.
Object Type: Article
System: The UNT Digital Library
Valence-state Model of Strain-dependent Mn L2,3 X-ray Magnetic Circular Dichroism from Ferromagnetic Semiconductors (open access)

Valence-state Model of Strain-dependent Mn L2,3 X-ray Magnetic Circular Dichroism from Ferromagnetic Semiconductors

We present a valence-state model to explain the characteristics of a recently observed pre-edge feature in Mn L{sub 3} x-ray magnetic circular dichroism (XMCD) of ferromagnetic (Ga,Mn)As and (Al,Ga,Mn)As thin films. The prepeak XMCD shows a uniaxial anisotropy, contrary to the cubic symmetry of the main structures induced by the crystalline electric field. Reversing the strain in the host lattice reverses the sign of the uniaxial anisotropy. With increasing carrier localization, the prepeak height increases, indicating an increasing 3d character of the hybridized holes. Hence, the feature is ascribed to transitions from the Mn 2p core level to unoccupied p-d hybridized valence states. The characteristics of the prepeak are readily reproduced by the model calculation taking into account the symmetry of the strain-, spin-orbit-, and exchange-split valence states around the zone center.
Date: March 30, 2010
Creator: van der Laan, G.; Edmonds, K. W.; Arenholz, E.; Farley, N. R. S. & Gallagher, B. L.
Object Type: Article
System: The UNT Digital Library
Fault Locating, Prediction and Protection (FLPPS) (open access)

Fault Locating, Prediction and Protection (FLPPS)

One of the main objectives of this DOE-sponsored project was to reduce customer outage time. Fault location, prediction, and protection are the most important aspects of fault management for the reduction of outage time. In the past most of the research and development on power system faults in these areas has focused on transmission systems, and it is not until recently with deregulation and competition that research on power system faults has begun to focus on the unique aspects of distribution systems. This project was planned with three Phases, approximately one year per phase. The first phase of the project involved an assessment of the state-of-the-art in fault location, prediction, and detection as well as the design, lab testing, and field installation of the advanced protection system on the SCE Circuit of the Future located north of San Bernardino, CA. The new feeder automation scheme, with vacuum fault interrupters, will limit the number of customers affected by the fault. Depending on the fault location, the substation breaker might not even trip. Through the use of fast communications (fiber) the fault locations can be determined and the proper fault interrupting switches opened automatically. With knowledge of circuit loadings at the time …
Date: September 30, 2010
Creator: Yinger, Robert, J.; Venkata, S., S. & Centeno, Virgilio
Object Type: Report
System: The UNT Digital Library
Search for the Higgs Boson in $H\to WW^{*}\to\ell\nu\ell\nu$ Decays (open access)

Search for the Higgs Boson in $H\to WW^{*}\to\ell\nu\ell\nu$ Decays

We present a search for the standard model (SM) Higgs boson decaying to a pair of W bosons that in turn decay leptonically, H {yields} WW* {yields} {ell}{nu}{ell}{nu}. We consider events produced in p{bar p} collisions at {radical}s = 1.96 TeV, with two oppositely charged lepton candidates (e{sup +}e{sup -}, e{sup {+-}}{mu}{sup {+-}}, or {mu}{sup +}{mu}{sup -}), and missing transverse energy. The data were collected with the D0 detector at the Fermilab Tevatron collider, and correspond to an integrated luminosity of 5.4 fb{sup -1}. No excess of events over background is observed, and limits on SM Higgs boson production are determined.
Date: May 30, 2010
Creator: Gerbaudo, Davide
Object Type: Article
System: The UNT Digital Library
Integrated Program of Experimental Diagnostics at the NNSS: An Integrated, Prioritized Work Plan for Diagnostic Development and Maintenance and Supporting Capability (open access)

Integrated Program of Experimental Diagnostics at the NNSS: An Integrated, Prioritized Work Plan for Diagnostic Development and Maintenance and Supporting Capability

This Integrated Program of Experimental Diagnostics at the NNSS is an integrated prioritized work plan for the Nevada National Security Site (NNSS), formerly the Nevada Test Site (NTS), program that is independent of individual National Security Enterprise Laboratories’ (Labs) requests or specific Subprograms being supported. This prioritized work plan is influenced by national priorities presented in the Predictive Capability Framework (PCF) and other strategy documents (Primary and Secondary Assessment Technologies Plans and the Plutonium Experiments Plan). This document satisfies completion criteria for FY 2010 MRT milestone #3496: Document an integrated, prioritized work plan for diagnostic development, maintenance, and supporting capability. This document is an update of the 3‐year NNSS plan written a year ago, September 21, 2009, to define and understand Lab requests for diagnostic implementation. This plan is consistent with Lab interpretations of the PCF, Primary Assessment Technologies, and Plutonium Experiment plans.
Date: September 30, 2010
Creator: Division, NSTec Mission and Projects
Object Type: Report
System: The UNT Digital Library
The Impact of Rate Design and Net Metering on the Bill Savings from Distributed PV for Residential Customers in California (open access)

The Impact of Rate Design and Net Metering on the Bill Savings from Distributed PV for Residential Customers in California

Net metering has become a widespread policy in the U.S. for supporting distributed photovoltaics (PV) adoption. Though specific design details vary, net metering allows customers with PV to reduce their electric bills by offsetting their consumption with PV generation, independent of the timing of the generation relative to consumption - in effect, compensating the PV generation at retail electricity rates (Rose et al. 2009). While net metering has played an important role in jump-starting the residential PV market in the U.S., challenges to net metering policies have emerged in a number of states and contexts, and alternative compensation methods are under consideration. Moreover, one inherent feature of net metering is that the value of the utility bill savings it provides to customers with PV depends heavily on the structure of the underlying retail electricity rate, as well as on the characteristics of the customer and PV system. Consequently, the value of net metering - and the impact of moving to alternative compensation mechanisms - can vary substantially from one customer to the next. For these reasons, it is important for policymakers and others that seek to support the development of distributed PV to understand both how the bill savings varies …
Date: March 30, 2010
Creator: Darghouth, Naim; Barbose, Galen & Wiser, Ryan
Object Type: Report
System: The UNT Digital Library
Real-Time Control of Diesel Combustion Quality (open access)

Real-Time Control of Diesel Combustion Quality

Detroit Diesel Corporation (DDC) and ORNL established this CRADA to improve heavy-duty engine efficiency with reduced emissions at relatively extreme operating regimes such has high EGR, low-load, and cold-start, with an emphasis on the application of advanced control strategies. The approach used in this collaborative effort was to include the application of novel analysis and modeling techniques devel-oped from the application of nonlinear dynamics and chaos theory. More specifically, analytical tech-niques derived from these theories were to used to detect, characterize, and control the combustion insta-bilities that are responsible for poor combustion performance and corresponding high emissions. The foundation of this CRADA was established based on ORNL expertise on the fundamentals of ad-vanced combustion operation and experience with nonlinear dynamics and controls in combustion sys-tems. The initial plan was all data generation would be performed at DDC with an agreed upon experi-mental plan formed by both organizations. While numerous experiments were performed at DDC and the data was exchanged with ORNL researchers, the team decided to transfer an engine to ORNL to allow more flexibility and data generation opportunities. A prototype DDC Series 60 with a common rail fuel system was selected and installed at ORNL. DDC and ORNL maintained …
Date: June 30, 2010
Creator: Wagner, R. M. & Sisken, K.
Object Type: Report
System: The UNT Digital Library
First Principles Modeling of Phonon Heat Conduction in Nanoscale Crystalline Structures (open access)

First Principles Modeling of Phonon Heat Conduction in Nanoscale Crystalline Structures

The inability to remove heat efficiently is currently one of the stumbling blocks toward further miniaturization and advancement of electronic, optoelectronic, and micro-electro-mechanical devices. In order to formulate better heat removal strategies and designs, it is first necessary to understand the fundamental mechanisms of heat transport in semiconductor thin films. Modeling techniques, based on first principles, can play the crucial role of filling gaps in our understanding by revealing information that experiments are incapable of. Heat conduction in crystalline semiconductor films occurs by lattice vibrations that result in the propagation of quanta of energy called phonons. If the mean free path of the traveling phonons is larger than the film thickness, thermodynamic equilibrium ceases to exist, and thus, the Fourier law of heat conduction is invalid. In this scenario, bulk thermal conductivity values, which are experimentally determined by inversion of the Fourier law itself, cannot be used for analysis. The Boltzmann Transport Equation (BTE) is a powerful tool to treat non-equilibrium heat transport in thin films. The BTE describes the evolution of the number density (or energy) distribution for phonons as a result of transport (or drift) and inter-phonon collisions. Drift causes the phonon energy distribution to deviate from equilibrium, …
Date: June 30, 2010
Creator: Mazumder, Sandip & Li, Ju
Object Type: Report
System: The UNT Digital Library
Uranium-series comminution ages of continental sediments: Case study of a Pleistocene alluvial fan (open access)

Uranium-series comminution ages of continental sediments: Case study of a Pleistocene alluvial fan

Obtaining quantitative information about the timescales associated with sediment transport, storage, and deposition in continental settings is important but challenging. The uranium-series comminution age method potentially provides a universal approach for direct dating of Quaternary detrital sediments, and can also provide estimates of the sediment transport and storage timescales. (The word"comminution" means"to reduce to powder," reflecting the start of the comminution age clock as reduction of lithic parent material below a critical grain size threshold of ~;;50 mu m.) To test the comminution age method as a means to date continental sediments, we applied the method to drill-core samples of the glacially-derived Kings River Fan alluvial deposits in central California. Sediments from the 45 m core have independently-estimated depositional ages of up to ~;;800 ka, based on paleomagnetism and correlations to nearby dated sediments. We characterized sequentially-leached core samples (both bulk sediment and grain size separates) for U, Nd, and Sr isotopes, grain size, surface texture, and mineralogy. In accordance with the comminution age model, where 234U is partially lost from small sediment grains due to alpha recoil, we found that (234U/238U) activity ratios generally decrease with age, depth, and specific surface area, with depletions of up to 9percent relative …
Date: April 30, 2010
Creator: Lee, Victoria E.; DePaolo, Donald J. & Christensen, John N.
Object Type: Article
System: The UNT Digital Library
2009 Site Environmental Report (open access)

2009 Site Environmental Report

Each year, Brookhaven National Laboratory (BNL) prepares an annual Site Environmental Report (SER) in accordance with DOE Order 231.1A, Environment, Safety and Health Reporting of the U.S. Department of Energy. The report is written to inform the public, regulators, employees, and other stakeholders of BNL's environmental performance during the calendar year in review. The SER summarizes environmental data; environmental management performance; compliance with applicable DOE, federal, state, and local regulations; and compliance, restoration, and surveillance monitoring program performance. BNL has prepared annual SERs since 1971 and has documented nearly all of its environmental history since the Laboratory's inception in 1947. The report is available in print and as a downloadable file on the BNL web page at http://www.bnl.gov/ewms/ser/. A summary of the SER is also prepared each year to provide a general overview of the report, and is distributed with a CD of the full report.
Date: September 30, 2010
Creator: Ratel, K.M. & Laboratory, Brookhaven National
Object Type: Report
System: The UNT Digital Library
Relativistic warm plasma theory of nonlinear laser-driven electron plasma waves (open access)

Relativistic warm plasma theory of nonlinear laser-driven electron plasma waves

A relativistic, warm fluid model of a nonequilibrium, collisionless plasma is developed and applied to examine nonlinear Langmuir waves excited by relativistically-intense, short-pulse lasers. Closure of the covariant fluid theory is obtained via an asymptotic expansion assuming a non-relativistic plasma temperature. The momentum spread is calculated in the presence of an intense laser field and shown to be intrinsically anisotropic. Coupling between the transverse and longitudinal momentum variances is enabled by the laser field. A generalized dispersion relation is derived for langmuir waves in a thermal plasma in the presence of an intense laser field. Including thermal fluctuations in three velocity-space dimensions, the properties of the nonlinear electron plasma wave, such as the plasma temperature evolution and nonlinear wavelength, are examined, and the maximum amplitude of the nonlinear oscillation is derived. The presence of a relativistically intense laser pulse is shown to strongly influence the maximum plasma wave amplitude for non-relativistic phase velocities owing to the coupling between the longitudinal and transverse momentum variances.
Date: June 30, 2010
Creator: Schroeder, Carl B. & Esarey, Eric
Object Type: Article
System: The UNT Digital Library
Lessons Learned for the MICE Coupling Solenoid from the MICE Spectrometer Solenoids (open access)

Lessons Learned for the MICE Coupling Solenoid from the MICE Spectrometer Solenoids

Tests of the spectrometer solenoids have taught us some important lessons. The spectrometer magnet lessons learned fall into two broad categories that involve the two stages of the coolers that are used to cool the magnets. On the first spectrometer magnet, the problems were centered on the connection of the cooler 2nd-stage to the magnet cold mass. On the first test of the second spectrometer magnet, the problems were centered on the cooler 1st-stage temperature and its effect on the operation of the HTS leads. The second time the second spectrometer magnet was tested; the cooling to the cold mass was still not adequate. The cryogenic designs of the MICE and MuCOOL coupling magnets are quite different, but the lessons learned from the tests of the spectrometer magnets have affected the design of the coupling magnets.
Date: May 30, 2010
Creator: Green, Michael A.; Wang, Li; Pan, Heng; Wu, Hong; Guo, Xinglong; Li, S. Y. et al.
Object Type: Article
System: The UNT Digital Library
Energy Security, Innovation & Sustainability Initiative (open access)

Energy Security, Innovation & Sustainability Initiative

More than a dozen energy experts convened in Houston, Texas, on February 13, 2009, for the first in a series of four regionally-based energy summits being held by the Council on Competitiveness. The Southern Energy Summit was hosted by Marathon Oil Corporation, and participants explored the public policy, business and technological challenges to increasing the diversity and sustainability of U.S. energy supplies. There was strong consensus that no single form of energy can satisfy the projected doubling, if not tripling, of demand by the year 2050 while also meeting pressing environmental challenges, including climate change. Innovative technology such as carbon capture and storage, new mitigation techniques and alternative forms of energy must all be brought to bear. However, unlike breakthroughs in information technology, advancing broad-based energy innovation requires an enormous scale that must be factored into any equation that represents an energy solution. Further, the time frame for developing alternative forms of energy is much longer than many believe and is not understood by the general public, whose support for sustainability is critical. Some panelists estimated that it will take more than 50 years to achieve the vision of an energy system that is locally tailored and has tremendous diversity …
Date: April 30, 2010
Creator: unknown
Object Type: Report
System: The UNT Digital Library
New Fission-Product Waste Forms:  Development and Characterization (open access)

New Fission-Product Waste Forms: Development and Characterization

Research performed on the program “New Fission Product Waste Forms: Development and Characterization,” in the last three years has fulfilled the objectives of the proposal which were to 1) establish ceramic waste forms for disposing of Cs, Sr and minor actinides, 2) fully characterize the phase relationships, structures and thermodynamic and kinetic stabilities of promising waste forms, 3) establish a sound technical basis for understanding key waste form properties, such as melting temperatures and aqueous durability, based on an in-depth understanding of waste form structures and thermochemistry, and 4) establish synthesis, testing, scaleup and commercialization routes for wasteform implementation through out in-kind collaborations. In addition, since Cs and Sr form new elements by radioactive decay, the behavior and thermodynamics of waste forms containing different proportions of Cs, Sr and their decay products were discovered using non-radioactive analogues. Collaborations among researchers from three institutions, UC Davis, Sandia National Laboratories, and Shott Inc., were formed to perform the primary work on the program. The unique expertise of each of the members in the areas of waste form development, structure/property relationships, hydrothermal and high temperature synthesis, crystal/glass production, and thermochemistry was critical to program success. In addition, collaborations with the Brigham Young Univeristy, …
Date: July 30, 2010
Creator: Navrotsky, Alexandra
Object Type: Report
System: The UNT Digital Library
The Hydrogeologic Character of the Lower Tuff Confining Unit and the Oak Springs Butte Confining Unit in the Tuff Pile Area of Central Yucca Flat (open access)

The Hydrogeologic Character of the Lower Tuff Confining Unit and the Oak Springs Butte Confining Unit in the Tuff Pile Area of Central Yucca Flat

The lower tuff confining unit (LTCU) in the Yucca Flat Corrective Action Unit (CAU) consists of a monotonous sequence of pervasively zeolitized volcanic tuff (i.e., mostly bedded with lesser nonwelded to poorly welded tuff; not fractured) (Bechtel Nevada, 2006). The LTCU is an important confining unit beneath Yucca Flat because it separates the alluvial and volcanic aquifers, where many underground nuclear tests were conducted, from the regional lower carbonate aquifer. Recent sub-CAU-scale modeling by Los Alamos National Laboratory in the Tuff Pile area of Yucca Flat (Boryta, et al., in review) includes postulated low-porosity, high-permeability zones (i.e., fractured welded-tuff aquifers) within the LTCU. This scenario indicates that such postulated low-porosity, high-permeability zones could provide fast-path lateral conduits to faults, and eventually to the lower carbonate aquifer. A fractured and faulted lower carbonate aquifer is postulated to provide a flow path(s) for underground test-derived contaminants to potential offsite receptors. The ramifications of such a scenario are obvious for groundwater flow and contaminant migration beneath Yucca Flat. This paper describes the reasoning for not including postulated low-porosity, high-permeability zones within the LTCU in the Tuff Pile area or within the LTCU in the Yucca Flat CAU-scale model. Both observational and analytical data …
Date: July 30, 2010
Creator: Sigmund L. Drellack, Jr., Lance B. Prothro, Jose L. Gonzales, and Jennifer M. Mercadante
Object Type: Report
System: The UNT Digital Library
ZPR-3 Assembly 11 : A cylindrical sssembly of highly enriched uranium and depleted uranium with an average {sup 235}U enrichment of 12 atom % and a depleted uranium reflector. (open access)

ZPR-3 Assembly 11 : A cylindrical sssembly of highly enriched uranium and depleted uranium with an average {sup 235}U enrichment of 12 atom % and a depleted uranium reflector.

Over a period of 30 years, more than a hundred Zero Power Reactor (ZPR) critical assemblies were constructed at Argonne National Laboratory. The ZPR facilities, ZPR-3, ZPR-6, ZPR-9 and ZPPR, were all fast critical assembly facilities. The ZPR critical assemblies were constructed to support fast reactor development, but data from some of these assemblies are also well suited for nuclear data validation and to form the basis for criticality safety benchmarks. A number of the Argonne ZPR/ZPPR critical assemblies have been evaluated as ICSBEP and IRPhEP benchmarks. Of the three classes of ZPR assemblies, engineering mockups, engineering benchmarks and physics benchmarks, the last group tends to be most useful for criticality safety. Because physics benchmarks were designed to test fast reactor physics data and methods, they were as simple as possible in geometry and composition. The principal fissile species was {sup 235}U or {sup 239}Pu. Fuel enrichments ranged from 9% to 95%. Often there were only one or two main core diluent materials, such as aluminum, graphite, iron, sodium or stainless steel. The cores were reflected (and insulated from room return effects) by one or two layers of materials such as depleted uranium, lead or stainless steel. Despite their more …
Date: September 30, 2010
Creator: Lell, R. M.; McKnight, R. D.; Tsiboulia, A.; Rozhikhin, Y.; Security, National & Engineering, Inst. of Physics and Power
Object Type: Report
System: The UNT Digital Library
ZPR-3 Assembly 6f : A Spherical Assembly of Highly Enriched Uranium, Depleted Uranium, Aluminum and Steel With an Average {Sup 235}U Enrichment of 47 Atom %. (open access)

ZPR-3 Assembly 6f : A Spherical Assembly of Highly Enriched Uranium, Depleted Uranium, Aluminum and Steel With an Average {Sup 235}U Enrichment of 47 Atom %.

Over a period of 30 years, more than a hundred Zero Power Reactor (ZPR) critical assemblies were constructed at Argonne National Laboratory. The ZPR facilities, ZPR-3, ZPR-6, ZPR-9 and ZPPR, were all fast critical assembly facilities. The ZPR critical assemblies were constructed to support fast reactor development, but data from some of these assemblies are also well suited for nuclear data validation and to form the basis for criticality safety benchmarks. A number of the Argonne ZPR/ZPPR critical assemblies have been evaluated as ICSBEP and IRPhEP benchmarks. Of the three classes of ZPR assemblies, engineering mockups, engineering benchmarks and physics benchmarks, the last group tends to be most useful for criticality safety. Because physics benchmarks were designed to test fast reactor physics data and methods, they were as simple as possible in geometry and composition. The principal fissile species was {sup 235}U or {sup 239}Pu. Fuel enrichments ranged from 9% to 95%. Often there were only one or two main core diluent materials, such as aluminum, graphite, iron, sodium or stainless steel. The cores were reflected (and insulated from room return effects) by one or two layers of materials such as depleted uranium, lead or stainless steel. Despite their more …
Date: September 30, 2010
Creator: Lell, R. M.; McKnight, R. D; Schaefer, R. W. & Division, Nuclear Engineering
Object Type: Report
System: The UNT Digital Library
Water management technologies used by Marcellus Shale Gas Producers. (open access)

Water management technologies used by Marcellus Shale Gas Producers.

Natural gas represents an important energy source for the United States. According to the U.S. Department of Energy's (DOE's) Energy Information Administration (EIA), about 22% of the country's energy needs are provided by natural gas. Historically, natural gas was produced from conventional vertical wells drilled into porous hydrocarbon-containing formations. During the past decade, operators have increasingly looked to other unconventional sources of natural gas, such as coal bed methane, tight gas sands, and gas shales.
Date: July 30, 2010
Creator: Veil, J. A. & Division, Environmental Science
Object Type: Report
System: The UNT Digital Library
Final Report: Main Group Element Chemistry in Service of Hydrogen Storage and Activation (open access)

Final Report: Main Group Element Chemistry in Service of Hydrogen Storage and Activation

Replacing combustion of carbon-based fuels with alternative energy sources that have minimal environmental impact is one of the grand scientific and technological challenges of the early 21st century. Not only is it critical to capture energy from new, renewable sources, it is also necessary to store the captured energy efficiently and effectively for use at the point of service when and where it is needed, which may not be collocated with the collection site. There are many potential storage media but we focus on the storage of energy in chemical bonds. It is more efficient to store energy on a per weight basis in chemical bonds. This is because it is hard to pack electrons into small volumes with low weight without the use of chemical bonds. The focus of the project was the development of new chemistries to enable DOE to meet its technical objectives for hydrogen storage using chemical hydrogen storage systems. We provided computational chemistry support in terms of thermodynamics, kinetics, and properties prediction in support of the experimental efforts of the DOE Center of Excellence for Chemical Hydrogen Storage. The goal of the Center is to store energy in chemical bonds involving hydrogen atoms. Once the …
Date: September 30, 2010
Creator: Dixon, David A. & Anthony J. Arduengo, III
Object Type: Report
System: The UNT Digital Library