Country

The theory of hybrid stochastic algorithms (open access)

The theory of hybrid stochastic algorithms

These lectures introduce the family of Hybrid Stochastic Algorithms for performing Monte Carlo calculations in Quantum Field Theory. After explaining the basic concepts of Monte Carlo integration we discuss the properties of Markov processes and one particularly useful example of them: the Metropolis algorithm. Building upon this framework we consider the Hybrid and Langevin algorithms from the viewpoint that they are approximate versions of the Hybrid Monte Carlo method; and thus we are led to consider Molecular Dynamics using the Leapfrog algorithm. The lectures conclude by reviewing recent progress in these areas, explaining higher-order integration schemes, the asymptotic large-volume behaviour of the various algorithms, and some simple exact results obtained by applying them to free field theory. It is attempted throughout to give simple yet correct proofs of the various results encountered. 38 refs.
Date: November 21, 1989
Creator: Kennedy, A.D. (Florida State Univ., Tallahassee, FL (USA). Supercomputer Computations Research Inst.)
Object Type: Article
System: The UNT Digital Library
Experimental determination of lower plenum ECC injection effectiveness (open access)

Experimental determination of lower plenum ECC injection effectiveness

The effectiveness of lower plenum emergency core coolant (ECC) injection during a double ended offset shear cold leg break loss-of-coolant accident (LOCA) was investigated experimentally in a small-scale model of a pressurized water reactor (PWR). In order to determine relative merit of the lower plenum injection concept to mitigate the severity of a large break LOCA, data from lower plenum injection experiments were compared to data from an experiment in the Semiscale Mod-3 sytem in which cold leg ECC injection was utilized. The results indicated that lower plenum injection was extremely effective in initiating early reflooding of the core and earlier rod quenching than was observed in the cold leg injection experiment.
Date: November 21, 1980
Creator: Hanson, R.G.
Object Type: Article
System: The UNT Digital Library
Icelandic basaltic geothermal field: A natural analog for nuclear waste isolation in basalt (open access)

Icelandic basaltic geothermal field: A natural analog for nuclear waste isolation in basalt

Analog studies of Icelandic geothermal fields have shown that the design of nuclear waste repositories in basalt can benefit by comparison to the data base already available from the development of these geothermal fields. A high degree of similarity exists between these two systems: their petrology, groundwater geochemistry, mineral solubilities, hydrologic parameters, temperature ranges, water-rock redox equilibria, hydrothermal pH values, and secondary mineralogies all show considerable overlap in the range of values. The experimentally-simulated hydrothermal studies of the basaltic nuclear waste repository rocks have, at this time, produced a data base that receives a strong confirmation from the Icelandic analog. Furthermore, the Icelandic analog should eventually be employed to extrapolate into higher and lower temperatures, into longer time-base chemical comparisons, and into more realistic mineral deposition studies, than have been possible in the laboratory evaluations of the nuclear waste repository designs. This eventual use of the Icelandic analog will require cooperative work with the Icelandic Geological Survey. 46 refs., 4 figs., 2 tabs.
Date: November 21, 1984
Creator: Ulmer, G. C. & Grandstaff, D. E.
Object Type: Report
System: The UNT Digital Library
Development of Electrochemical Photovoltaic Cells. Second Technical Progress Report, August 1, 1979-October 31, 1979 (open access)

Development of Electrochemical Photovoltaic Cells. Second Technical Progress Report, August 1, 1979-October 31, 1979

The development of stable, efficient, photoelectrochemical cells based on silicon and gallium arsenide in non-aqueous electrolyte systems is being investigated. Redox reactions of ferrocene, anthracene and anthraquinone have been studied on platinum and n-silicon electrodes. The latter have been further characterized by differential capacitance measurements. Cells and equipment have been designed and set up for long-term stability studies.
Date: November 21, 1979
Creator: Austin, A. E.; Byker, H. J. & Brooman, E. W.
Object Type: Report
System: The UNT Digital Library
GENERATING THE RIGHT PCB DATA DETERMINATION OF AROCLORS VERSUS PCB CONGENERS (open access)

GENERATING THE RIGHT PCB DATA DETERMINATION OF AROCLORS VERSUS PCB CONGENERS

Polychlorinated biphenyls (PCBs) are a major environmental concern due to their ubiquity and tendency to bio-accumulate. as well as their persistence and toxicity. As the cleanup of waste and contaminated soil progresses at U.S. Department of Energy (DOE) sites, the costs for accurate PCB data are increasing. PCBs are actually a broad name for a group of 209 individual compounds known as congeners. PCBs were originally produced in the United States as specific mixtures of congeners known as Aroclors'. PCBs can be analyzed and quantified either as Aroclor mixtures or as individual congeners. Aroclor analysis, which is the more common analytical method applied to PCBs. has been in use for decades, and in general, most cleanup regulations are based on total PCB concentrations using Aroclor analyses. Congener analysis is relatively new to environmental cleanup and restoration due to both technical issues and associated cost. The benefits of congener analysis are that it allows a more direct analysis of the risk of the PCBs. The World Health Organization (WHO) has identified twelve specific congeners as dioxin-like with toxicity ranging from 0.00003 to 0.1 times the standard 2,3,7.8-Tetrachlorodibenzo-p-dioxin (2.3.7.8-TCDD) toxicity. This paper defines Aroclors and congeners and compares the current application and …
Date: November 21, 2007
Creator: CT, NARQUIS & AL, PRIGNANO
Object Type: Article
System: The UNT Digital Library
Bacillus atrophaeus Outer Spore Coat Assembly and Ultrastructure (open access)

Bacillus atrophaeus Outer Spore Coat Assembly and Ultrastructure

Our previous atomic force microscopy (AFM) studies successfully visualized native Bacillus atrophaeus spore coat ultrastructure and surface morphology. We have shown that the outer spore coat surface is formed by a crystalline array of {approx}11 nm thick rodlets, having a periodicity of {approx}8 nm. We present here further AFM ultrastructural investigations of air-dried and fully hydrated spore surface architecture. In the rodlet layer, planar and point defects, as well as domain boundaries, similar to those described for inorganic and macromolecular crystals, were identified. For several Bacillus species, rodlet structure assembly and architectural variation appear to be a consequence of species-specific nucleation and crystallization mechanisms that regulate the formation of the outer spore coat. We propose a unifying mechanism for nucleation and self-assembly of this crystalline layer on the outer spore coat surface.
Date: November 21, 2005
Creator: Plomp, M; Leighton, T J; Wheeler, K E; Pitesky, M E & Malkin, A J
Object Type: Article
System: The UNT Digital Library
REFINEMENT OF THE NEPHELINE DISCRIMINATOR: RESULTS OF A PHASE II STUDY (open access)

REFINEMENT OF THE NEPHELINE DISCRIMINATOR: RESULTS OF A PHASE II STUDY

Twenty five glass compositions were selected for a Phase II study to assess the potential for reducing the conservatism in the nepheline discriminator. The glass compositions were restricted to regions that fell within the validation ranges of the DWPF PCCS models. In addition, the liquidus temperature model was used to restrict the glass compositions so that they could all be melted at the same temperature. The nepheline discriminator was used to force the glass compositions into regions where nepheline formation was predicted to occur. The glasses were fabricated in the laboratory and characterized for crystallization and chemical durability after both quenching and slow cooling. Chemical analysis showed that the fabricated glasses met the target compositions. Nepheline was identified in one of the quenched glasses and several of the CCC glasses. There was no clear relationship between the types of crystallization that occurred in a particular glass and its location on the Al{sub 2}O{sub 3}-Na{sub 2}O-SiO{sub 2} ternary diagram. A partitioning algorithm was used to identify trends in crystallization behavior based on glass composition. Generally, for the CCC glasses MnO influenced the crystallization of spinels and B{sub 2}O{sub 3} and SiO{sub 2} influenced the crystallization of nepheline. Measured durability responses varied …
Date: November 21, 2008
Creator: Fox, K & Tommy Edwards, T
Object Type: Report
System: The UNT Digital Library
K-alpha conversion efficiency measurments for x-ray scattering in inertial confinement fusion plasmas (open access)

K-alpha conversion efficiency measurments for x-ray scattering in inertial confinement fusion plasmas

The conversion efficiency of ultra short-pulse laser radiation to K-{alpha} x-rays has been measured for various chlorine-containing targets to be used as x-ray scattering probes of dense plasmas. The spectral and temporal properties of these sources will allow spectrally-resolved x-ray scattering probing with picosecond temporal resolution required for measuring the plasma conditions in inertial confinement fusion experiments. Simulations of x-ray scattering spectra from these plasmas show that fuel capsule density, capsule ablator density, and shock timing information may be inferred.
Date: November 21, 2006
Creator: Kritcher, A L; Neumayer, P; Urry, M K; Robey, H; Niemann, C; Landen, O L et al.
Object Type: Article
System: The UNT Digital Library
Colloid-Facilitated Transport of Radionuclides through the Vadose Zone (open access)

Colloid-Facilitated Transport of Radionuclides through the Vadose Zone

The main purpose of this project was to advance the basic scientific understanding of colloid and colloid-facilitated Cs transport of radionuclides in the vadose zone. We focused our research on the hydrological and geochemical conditions beneath the leaking waste tanks at the USDOE Hanford reservation. Specific objectives were (1) to determine the lability and thermodynamic stability of colloidal materials, which form after reacting Hanford sediments with simulated Hanford Tank Waste, (2) to characterize the interactions between colloidal particles and contaminants, i.e., Cs and Eu, (3) to determine the potential of Hanford sediments for \textit{in situ} mobilization of colloids, (4) to evaluate colloid-facilitated radionuclide transport through sediments under unsaturated flow, (5) to implement colloid-facilitated contaminant transport mechanisms into a transport model, and (6) to improve conceptual characterization of colloid-contaminant-soil interactions and colloid-facili\-tated transport for clean-up procedures and long-term risk assessment. We have previously shown that upon contact with simulated waste tank solutions, Hanford sediments change their mineralogical composition. Certain minerals, i.e., quartz, smectite, and kaolinite, are partially dissolved, and new mineral phases, i.e., the feldspathoids cancrinite and sodalite, are formed. We have characterized these mineral transformations and clarified the mineral transformation pathways. The new minerals were mainly in the colloidal size …
Date: November 21, 2006
Creator: Flury, Markus; Harsh, James B.; McCarthy, John F.; Lichtner, Peter C. & Zachara, John M.
Object Type: Report
System: The UNT Digital Library
HYDROGEN AND VOC RETENTION IN WASTE BOXES (open access)

HYDROGEN AND VOC RETENTION IN WASTE BOXES

The Hanford Waste Management Project Master Documented Safety Analysis (MDSA) (HNF-14741, 2003) identifies derived safety controls to prevent or mitigate the risks of a single-container deflagration during operations requiring moving, venting or opening transuranic (TRU)-waste containers. The issue is whether these safety controls are necessary for operations involving TRU-waste boxes that are being retrieved from burial at the Hanford Site. This paper investigates the potential for a deflagration hazard within these boxes and whether safety controls identified for drum deflagration hazards should be applied to operations involving these boxes. The study evaluates the accumulation of hydrogen and VOCs within the waste box and the transport of these gases and vapors out of the waste box. To perform the analysis, there were numerous and major assumptions made regarding the generation rate and the transport pathway dimensions and their number. Since there is little actual data with regards to these assumptions, analyses of three potential configurations were performed to obtain some indication of the bounds of the issue (the concentration of hydrogen or flammable VOCs within a waste box). A brief description of each of the three cases along with the results of the analysis is summarized.
Date: November 21, 2008
Creator: ME, PACE & RM, MARUSICH
Object Type: Report
System: The UNT Digital Library
Development of Irradiation hardening of Unalloyed and ODS molybdenum during neurtron irradiation to low doses at 300C and 600C (open access)

Development of Irradiation hardening of Unalloyed and ODS molybdenum during neurtron irradiation to low doses at 300C and 600C

Unalloyed molybdenum and Oxide Dispersion Strengthened (ODS) molybdenum were irradiated at 300 C and 600 C in the high flux isotope reactor (HFIR) to neutron fluences of 0.2, 2.1, and 24.3 x 10{sup 24} n/m{sup 2} (E > 0.1 MeV), producing damage levels of 0.01, 0.1 and 1.3 Mo-dpa. Hardness measurements, electrical resistivity measurements, tensile testing, and Transmission Electron Microscopy (TEM) were used to assess the defect structure. Irradiation hardening was evident even at a damage level of 0.01 dpa resulting in a significant increase in yield stress, decrease in ductility, and elevation of the Ductile-to-Brittle Transition Temperature (DBTT). The observed size and number density of voids and loops as well as the measured irradiation hardening and electrical resistivity were found to increase sub-linearly with fluence over the range of exposure investigated. This supports the idea that the formation of the extended defects that produce irradiation hardening in molybdenum are the result of a nucleation and growth process rather than the formation of sessile defects directly from the displacement damage cascades. The formation of sessile defect clusters in the displacement cascade would be expected to result in a linear fluence dependence for the number density of defects followed by saturation …
Date: November 21, 2007
Creator: Cockeran, B. V. & Smith, R. W.
Object Type: Article
System: The UNT Digital Library
In-situ Studies of the Martensitic Transformation in Ti Thin Films using the Dynamic Transmission Microscope (DTEM) (open access)

In-situ Studies of the Martensitic Transformation in Ti Thin Films using the Dynamic Transmission Microscope (DTEM)

The {alpha} to {beta} transition in pure Ti occurs mainly by a 'martensitic type' phase transformation. In such transformations, growth rates and interface velocities tend to be very large, on the order of 10{sup 3} m/s, making it difficult to observe the transformation experimentally. With thin films, it becomes even more difficult to observe, since the large surface augments the nucleation and transformation rates to levels that require nanosecond temporal resolution for experimental observations. The elucidation of the transformational mechanisms in these materials yearns for an apparatus that has both high spatial and temporal resolution. We have constructed such an instrument at LLNL (the dynamical transmission electron microscope or DTEM) that combines pulsed lasers systems and optical pump-probe techniques with a conventional TEM. We have used the DTEM to observe the transient events of the {alpha}-{beta} transformation in nanocrystalline Ti films via single shot diffraction patterns with 1.5 ns resolution. With pulsed, nanosecond laser irradiation (pump laser), the films were heated at an extreme rate of 10{sup 10} K/s. was observed At 500 ns after the initial pump laser hit, the HCP, alpha phase was almost completely transformed to the BCC, beta phase. Post-mortem investigations of the laser treated films …
Date: November 21, 2005
Creator: LaGrange, T. B.; Campbell, G. H.; Colvin, J. D.; King, W. E.; Browning, N. D.; Armstrong, M. R. et al.
Object Type: Article
System: The UNT Digital Library
LOCALIZED CORROSION OF AUSTENITIC STAINLESS STEELEXPOSED TO MIXTURES OF PLUTONIUM OXIDE AND CHLORIDE SALTS (open access)

LOCALIZED CORROSION OF AUSTENITIC STAINLESS STEELEXPOSED TO MIXTURES OF PLUTONIUM OXIDE AND CHLORIDE SALTS

Laboratory corrosion tests were conducted to investigate the corrosivity of moist plutonium oxide/chloride (PuO{sub 2}/Cl-) salt mixtures on 304L and 316L stainless steel coupons. The tests exposed flat coupons for pitting evaluation and 'teardrop' stressed coupons for stress corrosion cracking (SCC) evaluation at room temperature to various mixtures of PuO{sub 2} and chloride-bearing salts for periods up to 500 days. The two flat coupons were placed so that the solid oxide/salt mixture contacted about one half of the coupon surface. One teardrop coupon was placed in contact with solid mixture; the second teardrop was in contact with the headspace gas only. The mixtures were loaded with nominally 0.5 wt % water under a helium atmosphere. Observations of corrosion ranged from superficial staining to pitting and SCC. The extent of corrosion depended on the total salt concentration and on the composition of the salt. The most significant corrosion was found in coupons that were exposed to 98 wt % PuO{sub 2}, 2 wt % chloride salt mixtures that contained calcium chloride. SCC was observed in two 304L stainless steel teardrop coupons exposed in solid contact to a mixture of 98 wt % PuO{sub 2}, 0.9 wt % NaCl, 0.9 wt % …
Date: November 21, 2008
Creator: Zapp, P; Kerry Dunn, K; Jonathan Duffey, J; Ron Livingston, R & Zane Nelson, Z
Object Type: Article
System: The UNT Digital Library
Naturalness and Higgs Decays in the MSSM with a Singlet (open access)

Naturalness and Higgs Decays in the MSSM with a Singlet

The simplest extension of the supersymmetric standard model--the addition of one singlet superfield--can have a profound impact on the Higgs and its decays. We perform a general operator analysis of this scenario, focusing on the phenomenologically distinct scenarios that can arise, and not restricting the scope to the narrow framework of the NMSSM. We reexamine decays to four b quarks and four {tau}'s, finding that they are still generally viable, but at the edge of LEP limits. We find a broad set of Higgs decay modes, some new, including those with four gluon final states, as well as more general six and eight parton final states. We find the phenomenology of these scenarios is dramatically impacted by operators typically ignored, specifically those arising from D-terms in the hidden sector, and those arising from weak-scale colored fields. In addition to sensitivity of m{sub z}, there are potential tunings of other aspects of the spectrum. In spite of this, these models can be very natural, with light stops and a Higgs as light as 82 GeV. These scenarios motivate further analyses of LEP data as well as studies of the detection capabilities of future colliders to the new decay channels presented.
Date: November 21, 2005
Creator: Chang, Spencer; Fox, Patrick J. & Weiner, Neal
Object Type: Article
System: The UNT Digital Library
Analysis of stirred-tank carbonation reactors. [Removal of /sup 14/CO/sub 2/ by reaction with Ca(OH)/sub 2/] (open access)

Analysis of stirred-tank carbonation reactors. [Removal of /sup 14/CO/sub 2/ by reaction with Ca(OH)/sub 2/]

The removal of CO/sub 2/ from air in a calcium hydroxide slurry-agitated reactor was investigated to aid the design of such vessels. Gas-liquid interfacial areas were calculated using theoretical rate expression and experimental data at specific operating conditions. A correlation for interfacial areas was then determined as a function of impeller speed, impeller diameter, gas flow rate, and concentration of the slurry. Decontamination factors were also determined.
Date: November 21, 1978
Creator: Sheppard, N.F.; Rizo-Patron, R.C. & Sun, W.H.
Object Type: Report
System: The UNT Digital Library
Evaluation of H/sub 2/S control technology for geothermal energy sources (open access)

Evaluation of H/sub 2/S control technology for geothermal energy sources

This study was conducted to identify processes that are most applicable for control of H/sub 2/S from geothermal sources. Both vapor-dominated and liquid-dominated sources were considered within the electric power generation category. The source characteristics, H/sub 2/S control requirements, and applicable technologies are discussed for the two geothermal sources. An evaluation of the applicable control technology indicates that there are three major approaches for H/sub 2/S removal. These are (a) upstream cleaning (ahead of the power plant), (b) removal of H/sub 2/S from condenser vent emissions, and (c) H/sub 2/S removal from cooling water, including condensate. The most promising processes for these emission points, based on current information, are as follows: the EIC process for upstream cleaning of liquid-dominated sources. For condenser vent emissions, the Stretford process appears to be most applicable; for cooling tower emissions, the iron catalyst process, followed by the H/sub 2/O/sub 2/ process, seems most appropriate.
Date: November 21, 1978
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Review of MFTF yin-yang magnet displacement and magnetic field measurements and calculations (open access)

Review of MFTF yin-yang magnet displacement and magnetic field measurements and calculations

During the recent testing of the MFTF yin-yang magnet, measurements of coil position, structural case strain, and magnetic field were made to verify calculated values. Measurements to detect magnet movement were taken throughout cooldown and during the operation of the magnet. The magnetic field at the mirror points was measured by Hall-effect probes. The magnet position, structural case strain, and magnetic field measurements indicated a reasonably close correlation with calculated values. Information obtained from the yin-yang test has been very useful in setting realistic mechanical alignment values for the new MFTF-B magnet system.
Date: November 21, 1983
Creator: Hanson, C. L.; Myall, J. O. & Wohlwend, J. W.
Object Type: Article
System: The UNT Digital Library
Mirror fusion vacuum technology developments (open access)

Mirror fusion vacuum technology developments

Magnetic Mirror Fusion experiments, such as MFTF-B+T (Mirror Fusion Test Facility-B, Tritium Upgrade) and foreseeable follow-on devices, have operational and maintenance requirements that have not yet been fully demonstrated. Among those associated with vacuum technology are the very-high continuous-pumping speeds, 10/sup 7/ to 10/sup 8/ l/s for D/sub 2/, T/sub 2/ and, to a lesser extent, He; the early detection of water leaks from the very-high heat-flux neutral-beam dumps and the detection and location of leaks in the superconducting magnets not protected by guard vacuums. Possible solutions to these problems have been identified and considerable progress has been made toward successfully demonstrating their feasibility.
Date: November 21, 1983
Creator: Batzer, T. H. & Call, W. R.
Object Type: Article
System: The UNT Digital Library
Detoxification and Generation of Useful Products From Coal Combustion Wastes (open access)

Detoxification and Generation of Useful Products From Coal Combustion Wastes

Electric utilities are on the brink of a new era in waste disposal problems. This research project addresses the issue of how to effectively dispose of flyash, bottom ash, desulfurization sludge through the generation of chemically-hardened material that could potentially be used as a cement or as a synthetic aggregate. The specific goals of this study were: (1) to study the hardness of mixtures of flyash, bottom ash, and DSG treated with lime and other hardening agents; (2) to determine the optimum solids content, setting time, moisture content, and post setting treatments that will yield the greatest strength and hardness out of these mixtures; and (3) to determine the leachability of the synthetic material as a measure of its ability to retain absorbed and/or entrained toxic metals. 50 refs., 15 figs., 8 tabs.
Date: November 21, 1990
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Waste water heat recovery appliance. Final report (open access)

Waste water heat recovery appliance. Final report

An efficient convective waste heat recovery heat exchanger was designed and tested. The prototype appliance was designed for use in laundromats and other small commercial operations which use large amounts of hot water. Information on general characteristics of the coin-op laundry business, energy use in laundromats, energy saving resources already in use, and the potential market for energy saving devices in laundromats was collected through a literature search and interviews with local laundromat operators in Fort Collins, Colorado. A brief survey of time-use patterns in two local laundromats was conducted. The results were used, with additional information from interviews with owners, as the basis for the statistical model developed. Mathematical models for the advanced and conventional types were developed and the resulting computer program listed. Computer simulations were made using a variety of parameters; for example, different load profiles, hold-up volumes, wall resistances, and wall areas. The computer simulation results are discussed with regard to the overall conclusions. Various materials were explored for use in fabricating the appliance. Resistance to corrosion, workability, and overall suitability for laundromat installations were considered for each material.
Date: November 21, 1983
Creator: Chapin, H. D.; Armstrong, P. R. & Chapin, F. A. W.
Object Type: Report
System: The UNT Digital Library
Spin motion of electrons in the SLC linac (open access)

Spin motion of electrons in the SLC linac

It is generally expected that the depolarizing effects of the linear accelerator RF fields will be small. Recently Bill Atwood raised the question whether this conclusion is still correct in view of the fact that the particles in the SLC spend a larger fraction of their time at phase angles off crest'' due to BNS damping; since radial fields are in quadrature with the accelerating field this might imply that depolarizing effects are larger. On the other hand, because of the smaller emittance of the SLC relative to the earlier linac radial excursions would be smaller. The anticipation is therefore that the depolarizing effect will again be negligible but it might be worthwhile to update the early calculations of SLAC TN-63-97 revised in this paper.
Date: November 21, 1990
Creator: Panofsky, W. K. H.
Object Type: Report
System: The UNT Digital Library
NWCF maintenance features and capabilities (open access)

NWCF maintenance features and capabilities

A New Waste Calcining Facility is being built at the Idaho Chemical Processing Plant to replace the existing Waste Calcining Facility which was built to demonstrate fluidized-bed solidification of highly radioactive liquid wastes. The new facility is being designed to provide a higher waste throughput, more corrosion resistant materials of construction, more effective cleanup of effluent streams, and extensive remote maintenance and equipment replacement capability. The facility will also contain extensive decontamination capability should contact maintenance become necessary. The facility is presently in construction and is scheduled for hot operation in 1980.
Date: November 21, 1978
Creator: Smith, R. R. & Bingham, G. E.
Object Type: Article
System: The UNT Digital Library
Followup review of major system aquisitions and major projects (open access)

Followup review of major system aquisitions and major projects

In 1985, we reviewed the Department's procedures and practices for managing and controlling its major acquisition program, both for major systems and major projects. The 1985 review resulted in the identification of significant deficiencies. We found, for example, deficiencies relating to documentation and reporting requirements for major acquisitions. The purpose of this review was to determine if this condition had been corrected. The review included an examination of applicable laws, Executive Orders, Office of Management and Budget (OMB) Circulars, and Department policies. We examined key documents prepared for major acquisitions and reviewed reports used by senior Departmental officials to monitor these projects. Our audit was based primarily on a limited review of documentation available at Department of Energy (DOE) Headquarters. We did not extend our review of the issues raised in this report because we concluded that the management of major acquisitions was of such importance to the Department at this time that expedited reporting was needed.
Date: November 21, 1990
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Materials performance in prototype Thermal Cycling Absorption Process (TCAP) columns (open access)

Materials performance in prototype Thermal Cycling Absorption Process (TCAP) columns

Two prototype Thermal Cycling Absorption Process (TCAP) columns have been metallurgically examined after retirement, to determine the causes of failure and to evaluate the performance of the column container materials in this application. Leaking of the fluid heating and cooling subsystems caused retirement of both TCAP columns, not leaking of the main hydrogen-containing column. The aluminum block design TCAP column (ABL block TCAP) used in the Advanced Hydride Laboratory, Building 773-A, failed in one nitrogen inlet tube that was crimped during fabrication, which lead to fatigue crack growth in the tube and subsequent leaking of nitrogen from this tube. The Third Generation stainless steel design TCAP column (Third generation TCAP), operated in 773-A room C-061, failed in a braze joint between the freon heating and cooling tubes (made of copper) and the main stainless steel column. In both cases, stresses from thermal cycling and local constraint likely caused the nucleation and growth of fatigue cracks. No materials compatibility problems between palladium coated kieselguhr (the material contained in the TCAP column) and either aluminum or stainless steel column materials were observed. The aluminum-stainless steel transition junction appeared to be unaffected by service in the AHL block TCAP. Also, no evidence of …
Date: November 21, 1992
Creator: Clark, E.A.
Object Type: Report
System: The UNT Digital Library