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Instrumentation and testing of a prestressed concrete containment vessel model

Description: Static overpressurization tests of two scale models of nuclear containment structures - a steel containment vessel (SCV) representative of an improved, boiling water reactor (BWR) Mark II design and a prestressed concrete containment vessel (PCCV) for pressurized water reactors (PWR) - are being conducted by Sandia National Laboratories for the Nuclear Power Engineering Corporation of Japan and the U.S. Nuclear Regulatory Commission. This paper discusses plans for instrumentation and testing of the PCCV model. 6 refs., 2 figs., 2 tabs.
Date: April 1, 1997
Creator: Hessheimer, M. F.; Pace, D. W. & Klamerus, E. W.
Partner: UNT Libraries Government Documents Department

Fire-Induced Response in Foam Encapsulants

Description: The paper provides a concise overview of a coordinated experimental/theoretical/numerical program at Sandia National Laboratories to develop an experimentally validated model of fire-induced response of foam-filled engineered systems for nuclear and transportation safety applications. Integral experiments are performed to investigate the thermal response of polyurethane foam-filled systems exposed to fire-like heat fluxes. A suite of laboratory experiments is performed to characterize the decomposition chemistry of polyurethane. Mass loss and energy associated with foam decomposition and chemical structures of the virgin and decomposed foam are determined. Decomposition chemistry is modeled as the degradation of macromolecular structures by bond breaking followed by vaporization of small fragments of the macromolecule with high vapor pressures. The chemical decomposition model is validated against the laboratory data. Data from integral experiments is used to assess and validate a FEM foam thermal response model with the chemistry model developed from the decomposition experiments. Good agreement was achieved both in the progression of the decomposition front and the in-depth thermal response.
Date: April 2, 1999
Creator: Borek, T.T.; Chu, T.Y.; Erickson, K.L.; Gill, W.; Hobbs, M.L.; Humphries, L.L. et al.
Partner: UNT Libraries Government Documents Department

SCDAP/RELAP5 modeling of fluid heat transfer and flow losses through porous debris in a light water reactor

Description: The SCDAP/RELAP5 code is being developed at the Idaho National Engineering and Environmental Laboratory under the primary sponsorship of the U.S. Nuclear Regulatory Commission (NRC) to provide best-estimate transient simulations of light water reactor coolant systems during severe accidents. This paper describes the modeling approach used in the SCDAP/RELAP5 code to calculate fluid heat transfer and flow losses through porous debris that has accumulated in the vessel lower head and core regions during the latter stages of a severe accident. The implementation of heat transfer and flow loss correlations into the code is discussed, and calculations performed to assess the validity of the modeling approach are described. The different modes of heat transfer in porous debris include: (1) forced convection to liquid, (2) forced convection to gas, (3) nucleate boiling, (4) transition boiling, (5) film boiling, and (6) transition from film boiling to convection to vapor. The correlations for flow losses in porous debris include frictional and form losses. The correlations for flow losses were integrated into the momentum equations in the RELAP5 part of the code. Since RELAP5 is a very general non-homogeneous non-equilibrium thermal-hydraulics code, the resulting modeling methodology is applicable to a wide range of debris thermal-hydraulic conditions. Assessment of the SCDAP/RELAP5 debris bed thermal-hydraulic models included comparisons with experimental measurements and other models available in the open literature. The assessment calculations, described in the paper, showed that SCDAP/RELAP5 is capable of calculating the heat transfer and flow losses occurring in porous debris regions that may develop in a light water reactor during a severe accident.
Date: April 2, 2000
Creator: Harvego, E. A. & Siefken, L. J.
Partner: UNT Libraries Government Documents Department

Assessment of the reflood oxidation models in SCDAP/RELAP5/MOD3.1

Description: Reflooding of a hot damaged core following the start of a severe accident can lead to significant increases in the heating, melting, and oxidation of the core prior to the termination of the accident. These effects have been observed in bundle heating and melting experiments terminated by the addition of water and are postulated to have had a major impact on the accident progression in the TMI-2 accident. Although the detailed mechanisms for the processes are not completely understood, new SCDAP/RELAP5/MOD3.1e models, describing the cracking /spalling of oxidized fuel rod cladding during reflood, and the resulting oxidation of the underlying Zircaloy and relocating liquefied U-Zr-O, provide a reasonable estimate of the experimentally-observed bundle temperatures, hydrogen production, and changes in bundle geometry. This paper provides a brief description of the new models, selected highlights from code-to-data comparisons, and selected results from a recent set of calculations fro TMI-2 using the new models. The potential impact of these new models on other plant calculations is discussed in the concluding portion of this paper.
Date: April 1, 1996
Creator: Hohorst, J.K. & Allison, C.M.
Partner: UNT Libraries Government Documents Department

Parametric study of boiling heat transfer in porous media

Description: Detailed numerical modeling and parametric variation studies were conducted on boiling heat transfer processes in porous deposits with emphasis on applications associated with light water nuclear power reactor systems. The processes of boiling heat transfer in the porous corrosion deposits typically involve phase changes in finite volumetric regions in the porous media. The study examined such processes in two porous media configurations, without chimneys (homogeneous porous structures) and with chimneys (heterogeneous porous structures). A 1-D model and a 2-D model were developed to simulate two-phase flows with phase changes, without dry-out, inside the porous media for both structural configurations. For closure of the governing equations, an empirical correlation of the evaporation rate for phase changes inside the porous media was introduced. In addition, numerical algorithms were developed to solve the coupled nonlinear equations of mass, momentum, energy, capillary pressure, and evaporation rate. The distributions of temperature, thermodynamic saturation, liquid pressure, vapor pressure, liquid velocity, and vapor velocity were predicted. Furthermore, the effects of heat flux, system pressure, porosity, particle diameter, chimney population density, chimney radius, and crud thickness on the all superheat, critical heat flux, and minimum saturation were examined. The predictions were found to be in good agreement with the available experimental results.
Date: April 1, 1996
Creator: Shi, B.; Jones, B.G. & Pan, C.
Partner: UNT Libraries Government Documents Department

Can the multianvil apparatus really be used for high-pressure deformation experiments?

Description: Past claims of the suitability of the MA-8 multianvil press as a deformation apparatus may have been overstated. On the basis of measurements of final octahedron size and of guide block displacement as a function of time, using the 10/5, 14/8, and 18/11 assemblies (octahedron edge length in mm/truncation edge length in mm) with MgO octahedra and pyrophyllite gasketing, it appears that at run conditions of interest to most researchers there is no appreciable time-dependent creep of gaskets and octahedra. All inelastic deformation occurs at rather low pressures: below about 10 GPa for the 10/5, 7 GPa for the 14/8, and 6 GPa for the 18/11 assemblies, with substantial uncertainties in these pressures. Above these limits all deformation of the pressure medium is elastic. Pressure stepping as a means of increasing the inelastic deformation rate of a sample is probably ineffective. Displacement measured at the guide blocks, previously believed to indicate deformation of the gaskets and octahedron, appears now to be unrelated to creep of these components. The calibrations have not been exhaustive and there is considerable scatter in some of the size measurements, so the above conclusions are not unequivocal. The calibrations do not exclude the possibility of deformation of a few tens of microns after the attainment of high pressure. Efforts to impose permanent shape change to samples at high pressure and temperature simply by relying on long run durations must be viewed with skepticism. There may be possibilities for deformation in the multianvil apparatus if materials of contrasting elastic modulus are used to differentially load a sample during pressure stepping.
Date: April 24, 1996
Creator: Durham, W.B. & Rubie, D.C.
Partner: UNT Libraries Government Documents Department

Three-Body Collision Contributions to Recombination and Collision-Induced Dissociation. II. Kinetics

Description: Detailed rate constants for the reaction Ne + Ne + H {r_equilibrium} Ne{sub 2} + H are generated, and the master equations governing collision-induced dissociation (CID) and recombination are accurately solved numerically. The temperature and pressure dependence are explored. At all pressures, three-body (3B) collisions dominate. The sequential two-body energy-transfer (ET) mechanism gives a rate that is more than a factor of two too small at low pressures and orders of magnitude too small at high pressures. Simpler models are explored; to describe the kinetics they must include direct 3B rates connecting the continuum to the bound states and to the quasibound states. The relevance of the present reaction to more general CID/recombination reactions is discussed. For atomic fragments, the 3B mechanism usually dominates. For diatomic fragments,the 3B and ET mechanism are competitive, and for polyatomic fragments the ET mechanism usually dominates.
Date: April 10, 1998
Creator: Kendrick, Brian; Pack, Russell T. & Walker, Robert B.
Partner: UNT Libraries Government Documents Department

Thermodynamics and stability of the mixed-conducting Sr-Fe-Co-O system.

Description: Mixed-conducting Sr-Fe-Co oxides have potential applications in dense ceramic membranes for high-purity oxygen separation and/or methane conversion to produce syngas (CO + H{sub 2}), because of their combined high electronic/ionic conductivity and significant oxygen permeability. We studied the crystal structure and microstructure of the system in X-ray diffraction experiments and by using scanning electron microscopy, respectively. Thermogravimetric analysis was conducted on the SrFeCo{sub 0.5}O{sub x} sample in environments of various oxygen partial pressures (pO{sub 2}). Conductivity increased while weight decreased with increasing temperature. Activation energy decreased while conductivity increased with increasing pO{sub 2}. The pO{sub 2}-dependent conducting behavior of the SrFeCo{sub 0.5}O{sub x} system can be understood by considering the trivalent-to-divalent transition of transition-metal ions.
Date: April 28, 1999
Creator: Ma, B.
Partner: UNT Libraries Government Documents Department

Imaging of CO{sub 2} injection during an enhanced-oil-recovery experiment

Description: A series of time-lapse seismic cross well and single well experiments were conducted in a diatomite reservoir to monitor the injection of CO{sub 2} into a hydrofracture zone, using P- and S-wave data. During the first phase the set of seismic experiments were conducted after the injection of water into the hydrofrac-zone. The set of seismic experiments was repeated after a time period of 7 months during which CO{sub 2} was injected into the hydrofractured zone. The issues to be addressed ranged from the detectability of the geologic structure in the diatomic reservoir to the detectability of CO{sub 2} within the hydrofracture. During the pre-injection experiment, the P-wave velocities exhibited relatively low values between 1700-1900 m/s, which decreased to 1600-1800 m/s during the post-injection phase (-5 percent). The analysis of the pre-injection S-wave data revealed slow S-wave velocities between 600-800 m/s, while the post-injection data revealed velocities between 500-700 m/s (-6 percent). These velocity estimates produced high Poisson ratios between 0.36 and 0.46 for this highly porous ({approx} 50 percent) material. Differencing post- and pre-injection data revealed an increase in Poisson ratio of up to 5 percent. Both, velocity and Poisson estimates indicate the dissolution of CO{sub 2} in the liquid phase of the reservoir accompanied by a pore-pressure increase. The results of the cross well experiments were corroborated by single well data and laboratory measurements on core data.
Date: April 29, 2003
Creator: Gritto, Roland; Daley, Thomas M. & Myer, Larry R.
Partner: UNT Libraries Government Documents Department

Radioactive Material Transportation Considerations with Respect to DOE 3013 Storage Containers

Description: This paper evaluates sealed hardware that meets the requirements of DOE-STD-3013, ''Criteria for Preparing and packaging Plutonium Metals and Oxides for Long-Term Storage'' with respect to radioactive material (Type B quantity) transportation requirements. The Standard provides criteria for packaging of the plutonium materials for storage periods of at least 50 years. The standard requires the hardware to maintain integrity under both normal storage conditions and under anticipated handling conditions. To accomplish this, the standard requires that the plutonium be loaded in a minimum of two nested stainless steel sealed containers that are both tested for leak-tightness per ANSI N14.5. As such the 3013 hardware is robust. While the 3013 STD may provide appropriate storage criteria, it is not intended to provide criteria for transporting the material under the requirements of the Department of Transportation (DOT). In this evaluation, it is assumed that the activity of plutonium exceeds A1 and/or A2 curies as defined in DOT 49 CFR 173.431 and therefore must be shipped as a Type B package meeting the Nuclear Regulatory Commission (NRC) requirements of 10 CFR 71. The evaluation considers Type B shipment of plutonium in the 3013 hardware within a certified package for such contents.
Date: April 15, 2004
Creator: HENSEL, SJ
Partner: UNT Libraries Government Documents Department

A New Assessment of the LOFT-Wyle Blowdown Test WSB03R Using RELAP5-3D

Description: The RELAP-3D (version bt03) computer program was used to assess the LOFT-Wyle blowdown test (WSB03R). The primary goal of this new assessment is to represent faithfully the experimental facility and instrumentation using the latest three-dimensional fluid flow modeling capability available in RELAP5-3D. In addition, since RELAP5-3D represents a relatively new and significant upgrade to the capabilities of the RELAP5 series of computer programs, this study serves to add to its growing assessment base. The LOFT-Wyle Transient Fluid Calibration test facility consisted of an approximately 5.4m3 pressure vessel with a flow skirt which created an annulus that acted as a downcomer. An instrumented blowdown loop with an orfice was connected to the downcomer. This facility, built to calibrate the orfices used in several of the LOFT experiments, simulated the LOFT reactor vessel and broken loop cold leg. For the present assessment an existing RELAP5 model developed at INEEL was corrected and upgraded. The model corrections included: (1) employing the proper measured downcomer thickness, (2) positioning the experimental instrumentation in its correct location, and (3) setting the fluid conditions to their measured initial values. Model upgrades included: (1) use of a more finely-detailed fluid component nodalization, (2) explicit modeling of the experimental facility beyond the blowdown orifice, (3) addition of heat structure components to represent the heat capacity of structural material, and (4) use of three-dimensional fluid components to model asymmetrical portions of the facility. The new assessment highlights the need to model explicitly the effects of heat storage in structural materials for slowly evolving transients. The assessment also highlights the sensitivity of choked-flow limited calculations to: (1) the model employed, (2) input discharge coefficient values and/or (3) input nonequilibrium values. In addition, the present assessment demonstrates that an instability in the calculated liquid fraction at the base of the downcomer obtained ...
Date: April 16, 2002
Creator: Bandini, B.R.; Aumiller, D.L. & Tomlinson, E.T.
Partner: UNT Libraries Government Documents Department

Model for Residual Saturations and Capillary Imbibition and Drainage Pressures

Description: A pore saturation model expresses the capillary pressure as a function of a characteristic pore pressure and the wetting phase saturation. Singularity analyses of the total energies of the wetting and nonwetting phases give the residual saturations for the two phases. The total energy consists of a potential term and a work term associated with the effective pressure gradient for each phase. The derived residual wetting saturation is 0.236, and the derived residual nonwetting saturation is 0.884. The model includes separate pressures for imbibition and drainage to account for capillary hysteresis. In the model, the pressure gradient for the wetting phase defines the imbibition pressure, and the nonwetting phase pressure gradient defines the drainage pressure. At the residual nonwetting saturation, the two pressures differ by the characteristic pore pressure. The two pressures coincide at a critical minimum saturation of 0.301. The model also includes an entry head to account for the minimum force required for drainage to begin. The model utilizes a single fitting parameter, a characteristic pore pressure, which can be related to a characteristic pore diameter.
Date: April 1, 2004
Creator: LAURINAT, JAMESE
Partner: UNT Libraries Government Documents Department

An analytical model for calculating pressure rise in a room due to refrigerant spills from piping rupture

Description: In this paper, an analytical model is presented to describe quasi- steady release of a two-phase refrigerant mixture into a room and the associated pressure transient of the room atmosphere with limited capability to discharge the atmosphere. The analytical model is based on simple, approximate thermodynamic relationships applied along isentropes, which is used to describe the release of refrigerant and the coupled set of equation of energy and mass conservation and other auxiliary equations describing pressure transient of a room atmosphere. The analytical model, which consists of a set of nonlinear ordinary differential equations, is solved numerically by the Mathematica computer program. As an example the safety problem of a Freon-22 spill in a refrigeration equipment room, resulting from piping rupture due to an earthquake, is analyzed and discussed.
Date: April 1, 1995
Creator: Shin, Y.W.; Hsieh, B.J. & Kot, C.A.
Partner: UNT Libraries Government Documents Department

Correlation effects on stability in Pu metal and its alloys

Description: The existence of six crystallographic allotropes from room temperature up to the solid-liquid transition just above 913 K at atmospheric pressure makes solid Plutonium unique among the elements in the periodic table. Among these phases (labeled {alpha}, {beta}, {gamma}, {delta}{delta}{prime}), and {var_epsilon}, the {delta} phase, stable between 593 K and 736 K, has commanded considerable interest in the metallurgical and solid state communities. In contrast to the low-temperature monoclinic {alpha} phase, which is brittle, the face-centered cubic (fcc) {delta} phase is ductile, a property that makes it convenient for engineering applications. This phase can also be stabilized through alloying with a number of other elements such as Ga, Al, Sc, and Am.
Date: April 1, 1999
Creator: Cooper, B R; Gonis, A; Kiousis, N; Price, D L & Turchi, P E
Partner: UNT Libraries Government Documents Department

Hydrogen production by high-temperature water splitting using mixed oxygen ion-electron conducting membranes.

Description: Hydrogen production from water splitting at high temperatures has been studied with novel mixed oxygen ion-electron conducting cermet membranes. Hydrogen production rates were investigated as a function of temperature, water partial pressure, membrane thickness, and oxygen chemical potential gradient across the membranes. The hydrogen production rate increased with both increasing moisture concentration and oxygen chemical potential gradient across the membranes. A maximum hydrogen production rate of 4.4 cm{sup 3}/min-cm{sup 2} (STP) was obtained with a 0.10-mm-thick membrane at 900 C in a gas containing 50 vol.% water vapor in the sweep side. Hydrogen production rate also increased with decreasing membrane thickness, but surface kinetics play an important role as membrane thickness decreases.
Date: April 24, 2002
Creator: Lee, T. H.; Wang, S.; Dorris, S. E. & Balachandran, U.
Partner: UNT Libraries Government Documents Department

POTENTIAL FOR STRESS CORROSION CRACKING OF A537 CARBON STEEL NUCLEAR WASTE TANKS CONTAINING HIGHLY CAUSTIC SOLUTIONS

Description: The evaporator recycle streams of nuclear waste tanks may contain waste in a chemistry and temperature regime that exceeds the current corrosion control program, which imposes temperature limits to mitigate caustic stress corrosion cracking (CSCC). A review of the recent service history found that two of these A537 carbon steel tanks were operated in highly concentrated hydroxide solution at high temperature. Visual inspections, experimental testing, and a review of the tank service history have shown that CSCC has occurred in uncooled/un-stress relieved tanks of similar construction. Therefore, it appears that the efficacy of stress relief of welding residual stress is the primary corrosion-limiting mechanism. The objective of this experimental program is to test A537 carbon steel small scale welded U-bend specimens and large welded plates (30.48 x 30.38 x 2.54 cm) in a caustic solution with upper bound chemistry (12 M hydroxide and 1 M each of nitrate, nitrite, and aluminate) and temperature (125 C). These conditions simulate worst-case situations in these nuclear waste tanks. Both as-welded and stress-relieved specimens have been tested. No evidence of stress corrosion cracking was found in the U-bend specimens after 21 days of testing. The large plate test was completed after 12 weeks of immersion in a similar solution at 125 C except that the aluminate concentration was reduced to 0.3 M. Visual inspection of the plate revealed that stress corrosion cracking had not initiated from the machined crack tips in the weld or in the heat affected zone. NDE ultrasonic testing also confirmed subsurface cracking did not occur. Based on these results, it can be concluded that the environmental condition of these tests was unable to develop stress corrosion cracking within the test periods for the small welded U-bends and for the large plates, which were welded with an identical procedure as used ...
Date: April 26, 2010
Creator: Lam, P.; Stripling, C.; Fisher, D. & Elder, J.
Partner: UNT Libraries Government Documents Department

Hyperons in neutron stars

Description: Generalized beta equilibrium involving nucleons, hyperons, and isobars is examined for neutron star matter. The hyperons produce a considerable softening of the equation of state. It is shown that the observed masses of neutron stars can be used to settle a recent controversy concerning the nuclear compressibility. Compressibilities less than 200 MeV are incompatible with observed masses. 7 refs., 9 figs.
Date: April 1, 1986
Creator: Glendenning, N.K.
Partner: UNT Libraries Government Documents Department

Thermodynamics of high temperature brines

Description: Osmotic and activity coefficient data and enthalpy and heat capacity data for NaCl solutions at saturation pressure of water from 0 to 300{sup 0}C and to saturation composition have been simultaneously fit to a 30 parameter equation. The data are reproduced by the equation, in most cases, to within experimental error. Calculated values of the osmotic coefficient, the activity of water, the activity of NaCl, and the heat capacity, enthalpy and entropy of the solution are given in Tables in 25{sup 0}C intervals from 0 to 300{sup 0}C and concentrations from 0.25 to 25 wt% NaCl.
Date: April 1, 1979
Creator: Pitzer, K.S.; Bradley, D.J.; Rogers, P.S.Z. & Peiper, J.C.
Partner: UNT Libraries Government Documents Department

X-ray position detection in the region of 6. mu. m RMS with wire proportional chambers

Description: We have developed a MWPC system for x-ray detection with a position resolution in the region of 6 ..mu..m RMS (14 ..mu..m FWHM). The performance with argon, krypton or xenon at pressures from 1 to 10 atm is explored for the x-ray energy range 5 to 25 keV. At a resolution of 6 ..mu..m RMS the effects of photoelectron and Auger electron range, electronic noise, avalanche spread, lateral electron diffusion, as well as x-ray beam collimation, become of comparable magnitude. Their limiting effects on avalanche centroid fluctuation, and hence on position resolution, are investigated. The position resolution achieved in this work compares favorably with that of solid state devices. 7 refs., 6 figs.
Date: April 1, 1986
Creator: Fischer, J.; Radeka, V. & Smith, G.C.
Partner: UNT Libraries Government Documents Department

Transient analysis of a flywheel battery containment during a full rotor burst event.

Description: Flywheels are being developed for use in an Advanced Locomotive Propulsion System (ALPS) targeted for use in high speed passenger rail service. The ALPS combines high performance, high speed gas turbines, motor/generators and flywheels to provide a light-weight, fuel-efficient power system. Such a system is necessary to avoid the high cost of railway electrification, as is currently done for high speed rail service (>100mph) since diesels are too heavy. The light-weight flywheel rotors are made from multilayered composite materials, and are operated at extremely high energy levels. Metal containment structures have been designed to enclose the rotors and provide encapsulation of the rotor during postulated failure events. One such event is a burst mode failure of the rotor in which the composite rim is assumed to burst into debris that impacts against the containment. This paper presents a finite element simulation of the transient structural response of a subscale metal flywheel containment structure to a rotor burst event.
Date: April 17, 1998
Creator: Hsieh, B. J.
Partner: UNT Libraries Government Documents Department

Crack initiation in smooth fatigue specimens of austenitic stainless steel in light water reactor environments.

Description: The fatigue design curves for structural materials specified in Section III of the ASME Boiler and Pressure Vessel Code are based on tests of smooth polished specimens at room temperature in air. The effects of light water reactor (LWR) coolant environments are not explicitly addressed by the Code design curves; however, recent test data illustrate the detrimental effects of LWR coolant environments on the fatigue resistance of austenitic stainless steels (SSs). Certain loading and environmental conditions have led to test specimen fatigue lives that are significantly shorter than those obtained in air. Results of fatigue tests that examine the influence of reactor environments on crack initiation and crack growth of austenitic SSs are presented. Block loading was used to mark the fracture surface to determine crack length as a function of fatigue cycles in water environments, Crack lengths were measured by scanning electron microscopy. The mechanism for decreased fatigue life in LWR environments is discussed, and crack growth rates in the smooth fatigue specimens are compared with existing data from studies of crack growth rates.
Date: April 8, 1999
Creator: Chopra, O. K. & Smith, J. L.
Partner: UNT Libraries Government Documents Department

Residual stress effects in containment analysis.

Description: The manufacturing of steel containment vessels starts with the forming of flat plates into curved plates. A steel containment structure is made by welding individual plates together to form the sections that make up the complex shaped vessels. The metal forming and welding process leaves residual stresses in the vessel walls. Generally, the effect of metal forming residual stresses can be reduced or virtually eliminated by thermally stress relieving the vessel. In large containment vessels this may not be practical and thus, the residual stresses due to manufacturing may become important. The residual stresses could possibly affect the response of the vessel to internal pressurization. When the level of residual stresses is significant it will affect the vessel's response, for instance the yielding pressure and possibly the failure pressure. This paper will address the effect of metal forming residual stresses on the response of a generic pressure vessel to internal pressurization. A scoping analysis investigated the effect of residual forming stresses on the response of an internally pressurized vessel. A simple model was developed to gain understanding of the mechanics of the problem. Residual stresses due to the welding process were not considered in this investigation.
Date: April 24, 1998
Creator: Pfeiffer, P. A.
Partner: UNT Libraries Government Documents Department