Active and passive safety control performance in sub - critical, accelerator - driven nuclear reactors. (open access)

Active and passive safety control performance in sub - critical, accelerator - driven nuclear reactors.

Traditional safety performance requirements for nuclear reactors have been developed for critical reactors, whose kinetics characteristics differ significantly from sub-critical, accelerator-driven nuclear reactors. In a critical nuclear reactor, relatively small amounts of reactivity (negative or positive) can produce large changes in the fission rate. In sub-critical reactors, the self-multiplication (k) decreases as the sub-criticality (1-k) increases, and the responsiveness to small reactivity changes decreases. This makes sub-critical nuclear reactors less responsive to positive reactivity insertions than critical reactors. Also, larger negative reactivity insertions are needed in sub-critical reactors to shut down the fission chain if the neutron source remains. This paper presents the results from a computational analysis of the safety performance of sub-critical, accelerator-driven nuclear reactors. Coupled kinetics and thermal-hydraulics models are used to quantify the effectiveness of traditional protection and control system designs in sub-critical reactors. The analyses also quantify the role of inherent, passive reactivity feedback mechanisms in sub-critical reactors. Computational results are used to develop conclusions regarding the most favorable and effective means for reactor control and protection in sub-critical, accelerator-driven nuclear reactors.
Date: May 24, 2002
Creator: Cahalan, J. E. & Eriksson, M.
Object Type: Article
System: The UNT Digital Library
Animal Agriculture: Issues in the 107th Congress (open access)

Animal Agriculture: Issues in the 107th Congress

A variety of animal agriculture issues, including prices, the impact of consolidation in the meat production/packing industry, trade, and the environmental impacts of large feedlots, continue to generate interest in Congress. This issue brief discusses these issues, as well as the 2002 farm bill, which contains several provisions affecting animal agriculture, including protections for contract growers, disaster assistance, country-of-origin labeling, and increased funding for conservation purposes.
Date: May 24, 2002
Creator: Heykoop, Jerry
Object Type: Report
System: The UNT Digital Library
Apacheta, a new geothermal prospect in Northern Chile (open access)

Apacheta, a new geothermal prospect in Northern Chile

The discovery of two high-temperature fumaroles, with gas geochemistry compatible with an economic geothermal system, established Apacheta as one of the most attractive geothermal exploration prospects in northern Chile. These remote fumaroles at 5,150 m elevation were first sampled in 1999 by ENAP and its partners, following up on the reports of a CODELCO water exploration well that flowed small amounts of dry steam at 4,540 m elevation in the valley 4.5 km east of the fumaroles. The prospect is associated with a Plio-Pleistocene volcanic complex located within a NW-trending graben along the axis of the high Andes. The regional water table is 4,200 masl. There are no hot springs, just the 88 degrees C steam well and the 109 degrees and 118 degrees C fumaroles with gas compositions that indicate reservoir temperatures of greater than or equal to 250 degrees C, using a variety of gas geothermometers. An MT-TDEM survey was completed in 2001-2002 by Geotermica del Norte (SDN), an ENAP-C ODELCO partnership, to explore the Apacheta geothermal concession. The survey results indicated that base of the low resistivity clay cap has a structural apex just west of the fumaroles, a pattern typically associated with shallow permeability within a …
Date: May 24, 2002
Creator: Urzua, Luis; Powell, Tom; Cumming, William B. & Dobson, Patrick
Object Type: Article
System: The UNT Digital Library
Coast Guard: Vessel Identification System Development Needs to Be Reassessed (open access)

Coast Guard: Vessel Identification System Development Needs to Be Reassessed

A letter report issued by the General Accounting Office with an abstract that begins "The September 11th attacks emphasized the need for sound government information management of potential risks to U.S. assets and citizens. One possible source of that risk is through the vessels that navigate our ports and waterways. Whereas most large commercial vessels and many large recreational vessels obtain federal documentation, most smaller vessels are registered only in the state where they are primarily used. Congress, in 1998, required the Secretary of Transportation to develop a system to share individual states' vessel information as well as information on federally documented vessels. Fourteen years after legislation required the Coast Guard to develop a vessel identification system (VIS), no such system exists. In 1995 the agency contracted to develop the Marine Information for Safety and Law Enforcement system, of which VIS was a subcomponent. The Coast Guard accepted the contractor-developed VIS in 1998 despite system performance problems, intending to resolve these problems as the system evolved. However, the Coast Guard later found that there was no viable way to correct these problems, and that the cost to populate the system with states' data would be high. Even though the Coast …
Date: May 24, 2002
Creator: United States. General Accounting Office.
Object Type: Report
System: The UNT Digital Library
Cuba: Issues for the 107th Congress (open access)

Cuba: Issues for the 107th Congress

This report examines the economic and political situation in Cuba, including the human rights situation, and U.S. policy toward Cuba. The report also analyzes a number of issues facing Congress in U.S. policy toward Cuba, including: the overall direction of U.S. policy; challenges to U.S. policy in the World Trade Organization; restrictions on commercial food and medical exports; restrictions on travel; bilateral drug trafficking cooperation; Cuba and terrorism; funding for U.S.-government sponsored radio and television broadcasting to Cuba; the Russian signals intelligence facility in Cuba; migration issues; and compensation to the families of those Americans killed in 1996 when Cuba shot down two U.S. civilian planes. The report cites legislation that was passed in the 106th Congress, and also tracks legislative action on these various issues in U.S. policy toward Cuba in the 107th Congress.
Date: May 24, 2002
Creator: Sullivan, Mark P. & Taft-Morales, Maureen
Object Type: Report
System: The UNT Digital Library
Developing high brightness and high current beams for HIF injectors (open access)

Developing high brightness and high current beams for HIF injectors

The US Heavy Ion Fusion Virtual National Laboratory is continuing research into ion sources and injectors that simultaneously provide high current (0.5-1.0 Amps) and high brightness (normalized emittance better than 1.0 {pi}-mm-mr). The central issue of focus is whether to continue pursuing the traditional approach of large surface ionization sources or to adopt a multiaperture approach that transports many smaller ''beamlets'' separately at low energies before allowing them to merge. For the large surface source concept, the recent commissioning of the 2-MeV injector for the High Current eXperiment has increased our understanding of the beam quality limitations for these sources. We have also improved our techniques for fabricating large diameter aluminosilicate sources to improve lifetime and emission uniformity. For the multiaperture approach, we are continuing to study the feasibility of small surface sources and a RF induced plasma source in preparation for beamlet merging experiments, while continuing to run computer simulations for better understanding of this alternate concept. Experiments into both architectures will be performed on a newly commissioned ion source test stand at LLNL called STS-500. This stand test provides a platform for testing a variety of ion sources and accelerating structures with 500 kV, 17-microsecond pulses. Recent progress …
Date: May 24, 2002
Creator: Ahle, Larry; Grote, Dave & Kwan, Joe
Object Type: Article
System: The UNT Digital Library
Experimental Cross Sections for Reactions of Heavy Ions and 208Pb, 209Bi, 238U, and 248Cm Targets (open access)

Experimental Cross Sections for Reactions of Heavy Ions and 208Pb, 209Bi, 238U, and 248Cm Targets

The study of the reactions between heavy ions and {sup 208}Pb, {sup 209}Bi, {sup 238}U, and {sup 248} Cm targets was performed to look at the differences between the cross sections of hot and cold fusion reactions. Experimental cross sections were compared with predictions from statistical computer codes to evaluate the effectiveness of the computer code in predicting production cross sections. Hot fusion reactions were studied with the MG system, catcher foil techniques and the Berkeley Gas-filled Separator (BGS). 3n- and 4n-exit channel production cross sections were obtained for the {sup 238}U({sup 18}O,xn){sup 256-x}Fm, {sup 238}U({sup 22}Ne,xn){sup 260-x}No, and {sup 248}Cm({sup 15}N,xn){sup 263-x}Lr reactions and are similar to previous experimental results. The experimental cross sections were accurately modeled by the predictions of the HIVAP code using the Reisdorf and Schaedel parameters and are consistent with the existing systematics of 4n exit channel reaction products. Cold fusion reactions were examined using the BGS. The {sup 208}Pb({sup 48}Ca,xn){sup 256-x}No, {sup 208}Pb({sup 50}Ti,xn){sup 258-x}Rf, {sup 208}Pb({sup 51}V,xn){sup 259-x}Db, {sup 209}Bi({sup 50}Ti,xn){sup 259-x}Db, and {sup 209}Bi({sup 51}V,xn){sup 260-x}Sg reactions were studied. The experimental production cross sections are in agreement with the results observed in previous experiments. It was necessary to slightly alter the Reisdorf …
Date: May 24, 2002
Creator: Patin, Joshua B.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Glass dissolution rates from static and flow-through tests. (open access)

Glass dissolution rates from static and flow-through tests.

We measured the dissolution rate of a simple five-component glass at 70 C using static tests and single-pass flowthrough (SPFT) tests with pH buffers at pH values of 6.2, 8.3, and 9.6. The two methods yielded similar rates; however, the measured rates are about 10X higher than the rates measured previously for a glass having the same composition using an SPFT test method. Differences are attributed to how the effect of the solution flow rate on the glass dissolution rate was taken into account and how the surface area of crushed glass was estimated. The differences indicate the need to standardize the SPFT test procedure.
Date: May 24, 2002
Creator: Jeong, S.-Y. & Ebert, W. L.
Object Type: Article
System: The UNT Digital Library
Highway Research: Systematic Selection and Evaluation Processes Needed for Research Program (open access)

Highway Research: Systematic Selection and Evaluation Processes Needed for Research Program

A letter report issued by the General Accounting Office with an abstract that begins "The Federal Highway Administration (FHWA) has received hundreds of millions of dollars for its surface transportation research and technology program during the past decade. For example, in 1998 the Transportation Equity Act for the 21st Century, included over $447 million for fiscal year 2002 for FHWA's transportation research and technology efforts for six-year period of 1998 through 2003. FHWA's research and technology program is complex because each of the program offices within the agency are responsible for identifying research needs, formulating strategies to address transportation problems, and setting goals that support the agency's strategic goals. One business unit at FHWA's research laboratory provides support for administering the overall program and conducts some of the research. The agency's leadership team provides periodic oversight of the overall program. FHWA's processes for managing the research and technology program, and in particular for developing research agendas and evaluating research outcomes against intended results, do not always align with the best practices for similar federal research and technology programs. FHWA acknowledges that its approach for developing research agenda and involving external stakeholders in determining the direction of the program's research lacks …
Date: May 24, 2002
Creator: United States. General Accounting Office.
Object Type: Report
System: The UNT Digital Library
Improvement in brightness of multicusp-plasma ion source (open access)

Improvement in brightness of multicusp-plasma ion source

The beam brightness of a multicusp-plasma ion source has been substantially improved by optimizing the source configuration and extractor geometry. The current density of a 2 keV He{sup +} beam extracted from a 7.5-cm-diameter source operating at 2.5 kW RF power is {approx}100 mA/cm{sup 2}, which is {approx}10 times larger than that of a beam extracted from a 5-cm-diameter source operating at 1 kW RF power. A smaller focused beam spot size is achieved with a counter-bored extractor instead of a conventional (''through-hole'') extractor, resulting another order of magnitude improvement in beam current density. Measured brightness can be as high as 440 A/cm{sup 2}Sr, which represents a 30 times improvement over prior work.
Date: May 24, 2002
Creator: Ji, Q.; Jiang, X.; King, T-J.; Leung, K. N.; Standiford, K. & Wilde, S.B.
Object Type: Article
System: The UNT Digital Library
Internships and Fellowships: Congressional, Federal, and Other Work Experience Opportunities (open access)

Internships and Fellowships: Congressional, Federal, and Other Work Experience Opportunities

This report provides names of organizations, like the American Association for the Advancement of Science, which sponsors fellowships on Capitol Hill. This report lists Internet sites on internships and fellowships, such as the Smithsonian Institution's Web site on internships.
Date: May 24, 2002
Creator: Greenfield, Susan Watkins
Object Type: Report
System: The UNT Digital Library
Internships and Fellowships: Congressional, Federal, and Other Work Experience Opportunities (open access)

Internships and Fellowships: Congressional, Federal, and Other Work Experience Opportunities

None
Date: May 24, 2002
Creator: Greenfield, Susan Watkins
Object Type: Report
System: The UNT Digital Library
Issues in Implementing International Peace Operations (open access)

Issues in Implementing International Peace Operations

Correspondence issued by the General Accounting Office with an abstract that begins "Between fiscal years 1996 and 2001, the United States provided $3.45 billion in direct contributions and $24.2 billion in voluntary or indirect contributions to 33 U.N. peacekeeping operations in such areas as the Congo, Sierra Leone, Kosovo, Bosnia, and, most recently, Afghanistan. The prospects for implementing peace agreements are enhanced if all major parties to the conflict participate in negotiating the agreements and if these agreements include specific authority and mechanisms for their enforcement. Peace operations are more likely to succeed if the military forces carrying out the operations have clear objectives, sufficient resources, and the authority to carry out their tasks. Military forces can help create a secure environment for civilian work to proceed. Moreover, the slow or late deployment of a peace operation's civil administrators might impede efforts to establish good governance. Finally, peace operations tend to be more successful when locals participate at every reasonable opportunity."
Date: May 24, 2002
Creator: United States. General Accounting Office.
Object Type: Text
System: The UNT Digital Library
Measurement of gasoline spray propagation by means of synchrotron x- ray. (open access)

Measurement of gasoline spray propagation by means of synchrotron x- ray.

A quantitative and time-resolved radiographic technique has been used to characterize hollow-cone gasoline sprays in the near-nozzle region. The highly penetrative nature of x-rays promises the direct measurements of dense sprays that are difficult to study by visible-light based techniques. Time-resolved x-radiography measurement enables us to map the mass distribution near the spray nozzle, even immediately adjacent to the orifice. The quantitative nature of the measurement also permits the re-construction of spray structure and the progress of the spray development. It is observed that the speed of fuel injected in the later part of the injection is higher than injected earlier and that the initial fuel speed variation caused the spray plume to be compressed in space.
Date: May 24, 2002
Creator: Yue, Y.; Powell, C.; Cuenca , R.; Poola, R. & Wang, J.
Object Type: Article
System: The UNT Digital Library
Meat and Poultry Inspection Issues (open access)

Meat and Poultry Inspection Issues

This report discusses the U.S. Department of Agriculture's (USDA's) Food Safety and Inspection Service (FSIS) responsibility for inspecting most meat, poultry, and processed egg products for safety, wholesomeness, and proper labeling while detailing the results of congressional action in reducing the presence of pathogens and food-borne illness in facilities and food products.
Date: May 24, 2002
Creator: Rawson, Jean M.
Object Type: Report
System: The UNT Digital Library
Mesh refinement for particle-in-cell plasma simulations: Applications to - and benefits for - heavy ion fusion (open access)

Mesh refinement for particle-in-cell plasma simulations: Applications to - and benefits for - heavy ion fusion

The numerical simulation of the driving beams in a heavy ion fusion power plant is a challenging task, and simulation of the power plant as a whole, or even of the driver, is not yet possible. Despite the rapid progress in computer power, past and anticipated, one must consider the use of the most advanced numerical techniques, if they are to reach the goal expeditiously. One of the difficulties of these simulations resides in the disparity of scales, in time and in space, which must be resolved. When these disparities are in distinctive zones of the simulation region, a method which has proven to be effective in other areas (e.g., fluid dynamics simulations) is the mesh refinement technique. They discuss the challenges posed by the implementation of this technique into plasma simulations (due to the presence of particles and electromagnetic waves). They present the prospects for and projected benefits of its application to heavy ion fusion, in particular to the simulation of the ion source and the final beam propagation in the chamber. A Collaboration project is under way at LBNL between the Applied Numerical Algorithms Group (ANAG) and the HIF group to couple the Adaptive Mesh Refinement (AMR) library …
Date: May 24, 2002
Creator: Vay, J. L.; Colella, P.; McCorquodale, P.; Van Straalen, B.; Friedman, A. & Grote, D. P.
Object Type: Article
System: The UNT Digital Library
Mesoscale modeling of grain boundary migration under stress using coupled finite element and meshfree methods. (open access)

Mesoscale modeling of grain boundary migration under stress using coupled finite element and meshfree methods.

The process of grain boundary migration involves moving interfaces and topological changes of grain boundary geometry. This can not be effectively modeled by Lagrangian, Eulerian, or arbitrary Lagrangian Eulerian finite element formulation when stress effect is considered. A coupled finite element and meshfree approach is proposed for modeling of grain boundary migration under stress. In this formulation, the material grid carries material kinematic and kinetic variables, whereas the grain boundary grid carries grain boundary kinematic variables. The material domain is discretized by a reproducing kernel partition of unity with built-in strain discontinuity across the grain boundaries. The grain boundaries, on the other hand, are discretized by the standard finite elements. This approach allows an arbitrary evolution of grain boundaries without continuous remeshing.
Date: May 24, 2002
Creator: Chen, J.-S.; Lu, H.; Moldovan, D. & Wolf, D.
Object Type: Article
System: The UNT Digital Library
Nuclear Arms Control: The U.S.-Russian Agenda (open access)

Nuclear Arms Control: The U.S.-Russian Agenda

None
Date: May 24, 2002
Creator: Woolf, Amy F.
Object Type: Report
System: The UNT Digital Library
Parallel, Distributed Scripting with Python (open access)

Parallel, Distributed Scripting with Python

Parallel computers used to be, for the most part, one-of-a-kind systems which were extremely difficult to program portably. With SMP architectures, the advent of the POSIX thread API and OpenMP gave developers ways to portably exploit on-the-box shared memory parallelism. Since these architectures didn't scale cost-effectively, distributed memory clusters were developed. The associated MPI message passing libraries gave these systems a portable paradigm too. Having programmers effectively use this paradigm is a somewhat different question. Distributed data has to be explicitly transported via the messaging system in order for it to be useful. In high level languages, the MPI library gives access to data distribution routines in C, C++, and FORTRAN. But we need more than that. Many reasonable and common tasks are best done in (or as extensions to) scripting languages. Consider sysadm tools such as password crackers, file purgers, etc ... These are simple to write in a scripting language such as Python (an open source, portable, and freely available interpreter). But these tasks beg to be done in parallel. Consider the a password checker that checks an encrypted password against a 25,000 word dictionary. This can take around 10 seconds in Python (6 seconds in C). It …
Date: May 24, 2002
Creator: Miller, P J
Object Type: Article
System: The UNT Digital Library
Progress in the development of superconducting quadrupoles for heavy ion fusion (open access)

Progress in the development of superconducting quadrupoles for heavy ion fusion

The Heavy Ion Fusion program is developing single aperture superconducting quadrupoles based on NbTi conductor, for use in the High Current Experiment at Lawrence Berkeley National Laboratory. Following the fabrication and testing of prototypes using two different approaches, a baseline design has been selected and further optimized. A prototype cryostat for a quadrupole doublet, with features to accommodate induction acceleration modules, is being fabricated. The single aperture magnet was derived from a conceptual design of a quadrupole array magnet for multi-beam transport. Progress on the development of superconducting quadrupole arrays for future experiments is also reported.
Date: May 24, 2002
Creator: Faltens, A.; Lietzke, A.; Sabbi, G.; Seidl, P.; Lund, S.; Manahan, B. et al.
Object Type: Article
System: The UNT Digital Library
Reintroducing anisotropic interactions in magic-angle-spinning NMR of half-integer quadrupolar nuclei: 3D MQMAS (open access)

Reintroducing anisotropic interactions in magic-angle-spinning NMR of half-integer quadrupolar nuclei: 3D MQMAS

None
Date: May 24, 2002
Creator: Wi, Sungsool; Heise, Henrike & Pines, Alexander
Object Type: Article
System: The UNT Digital Library
RELAP5/MOD3.2 analysis of INSC standard problem INSCSP - R7 : void fraction distribution over RBMK fuel channel height for experiments performed in the ENTEK BM test facility. (open access)

RELAP5/MOD3.2 analysis of INSC standard problem INSCSP - R7 : void fraction distribution over RBMK fuel channel height for experiments performed in the ENTEK BM test facility.

The RELAP5/MOD3.2 computer program has been used to analyze a series of tests investigating void fraction distribution over height in RBMK fuel channels performed in Facility BM at the ENTEK. This is RBMK Standard Problem 7 in Joint Project 6, which is the investigation of Computer Code Validation for Transient Analysis of RBMK and VVER Reactors, between the United States and Russian Minatom International Nuclear Safety Centers. The experiment facility and data, RELAP5 nodalization, and results are shown for all tests. Agreement between RELAP5 and the experiment data is reasonable.
Date: May 24, 2002
Creator: Garner, P. L.
Object Type: Report
System: The UNT Digital Library
Restructured Electricity Markets: Three States' Experiences in Adding Generating Capacity (open access)

Restructured Electricity Markets: Three States' Experiences in Adding Generating Capacity

A letter report issued by the General Accounting Office with an abstract that begins "Twenty-four states and the District of Columbia have restructured electricity markets by shifting from service provided through a regulated monopoly to service provided through open competition among the local utilities and their competitors. The restructuring was intended to boost competition and expand consumer choice, increase efficiency, and lower prices. Of the three states GAO studied, Texas had the greatest need for additional electric power, and it added the most new capacity from 1995 through 2001. In contrast, California added 25 percent of the forecasted need for capacity over this period. Although Pennsylvania added less than half of its forecasted need for capacity, the state continues to be a net exporter of electricity to nearby states. The three states have similar processes for approving applications to build and operate new power plants. In all three states, state and local agencies must review the applications to ensure that the developer complies with environmental, land use, and other requirements before issuing the permits necessary to build and operate a power plant. California also has a state energy commission that reviews each power plant application to determine whether the benefits …
Date: May 24, 2002
Creator: United States. General Accounting Office.
Object Type: Report
System: The UNT Digital Library
ROCK DEFORMATION. Final Progress Report (open access)

ROCK DEFORMATION. Final Progress Report

The Gordon Research Conference (GRC) on ROCK DEFORMATION was held at II Ciocco from 5/19/02 thru 5/24/02. Emphasis was placed on current unpublished research and discussion of the future target areas in this field.
Date: May 24, 2002
Creator: unknown
Object Type: Article
System: The UNT Digital Library