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Validation of favor code linear elastic fracture solutions for finite-length flaw geometries

Description: One of the current tasks within the US Nuclear Regulatory Commission (NRC)-funded Heavy Section Steel Technology Program (HSST) at Oak Ridge National Laboratory (ORNL) is the continuing development of the FAVOR (Fracture, analysis of Vessels: Oak Ridge) computer code. FAVOR performs structural integrity analyses of embrittled nuclear reactor pressure vessels (RPVs) with stainless steel cladding, to evaluate compliance with the applicable regulatory criteria. Since the initial release of FAVOR, the HSST program has continued to enhance the capabilities of the FAVOR code. ABAQUS, a nuclear quality assurance certified (NQA-1) general multidimensional finite element code with fracture mechanics capabilities, was used to generate a database of stress-intensity-factor influence coefficients (SIFICs) for a range of axially and circumferentially oriented semielliptical inner-surface flaw geometries applicable to RPVs with an internal radius (Ri) to wall thickness (w) ratio of 10. This database of SIRCs has been incorporated into a development version of FAVOR, providing it with the capability to perform deterministic and probabilistic fracture analyses of RPVs subjected to transients, such as pressurized thermal shock (PTS), for various flaw geometries. This paper discusses the SIFIC database, comparisons with other investigators, and some of the benchmark verification problem specifications and solutions.
Date: April 1, 1995
Creator: Dickson, T.L.; Keeney, J.A. & Bryson, J.W.
Partner: UNT Libraries Government Documents Department

Carbon sequestration in natural gas reservoirs: Enhanced gas recovery and natural gas storage

Description: Natural gas reservoirs are obvious targets for carbon sequestration by direct carbon dioxide (CO{sub 2}) injection by virtue of their proven record of gas production and integrity against gas escape. Carbon sequestration in depleted natural gas reservoirs can be coupled with enhanced gas production by injecting CO{sub 2} into the reservoir as it is being produced, a process called Carbon Sequestration with Enhanced Gas Recovery (CSEGR). In this process, supercritical CO{sub 2} is injected deep in the reservoir while methane (CH{sub 4}) is produced at wells some distance away. The active injection of CO{sub 2} causes repressurization and CH{sub 4} displacement to allow the control and enhancement of gas recovery relative to water-drive or depletion-drive reservoir operations. Carbon dioxide undergoes a large change in density as CO{sub 2} gas passes through the critical pressure at temperatures near the critical temperature. This feature makes CO{sub 2} a potentially effective cushion gas for gas storage reservoirs. Thus at the end of the CSEGR process when the reservoir is filled with CO{sub 2}, additional benefit of the reservoir may be obtained through its operation as a natural gas storage reservoir. In this paper, we present discussion and simulation results from TOUGH2/EOS7C of gas mixture property prediction, gas injection, repressurization, migration, and mixing processes that occur in gas reservoirs under active CO{sub 2} injection.
Date: April 8, 2003
Creator: Oldenburg, Curtis M.
Partner: UNT Libraries Government Documents Department

Mean Stress and Environmental Effects on Fatigue in Type 304 Stainless Steel

Description: Fatigue life tests were performed in air on Type 304 stainless steel (304 SS) to establish the effect of mean stress under both load control and strain control. An apparent reduction of up to 26% in strain-amplitude occurred in the low and intermediate cycle regime (< 10{sup 8} cycles) for a mean stress of 138 Mpa. A quantitative description of mean stress effects using the Smith-Watson-Topper equivalent strain parameter was developed, which incorporates mean stress through the maximum stress. This description provided a tighter fit to the data, and allowed separation of mean stress and cold work effects. With this separation, the effect of mean stress was reduced to 12% decrease in strain amplitude at 138 Mpa. The stress-life curve apparently increased with increasing mean stress, due to the significant work hardening that occurred in tests with high mean stresses, especially under load control. Tests were performed on double-edge notched specimens of 304 SS in air and low oxygen water at 288 C. The elastically calculated increase in the notch tip stress accounted within 10% for the fatigue life reductions for a K{sub t} = 4.8 notch, but was 38% conservative for a K{sub t} = 8.8 notch. Fatigue crack initiation lives (defined as an 0.127 mm crack) in low oxygen water at 288 C were reduced by a factor of four to eight on cycles over those in air. Crack growth occurred throughout most of the fatigue ''initiation'' life. The increase in crack growth rate of 304 SS in water appears to be large enough to explain the reduced ''initiation'' life in this environment.
Date: April 1, 1999
Creator: Kandra, J.T.; Leax, T.R. & Wire, G.L.
Partner: UNT Libraries Government Documents Department

Preliminary assessment of the effects of biaxial loading on reactor pressure vessel structural-integrity-assessment technology

Description: Effects of biaxial loading on shallow-flaw fracture toughness were studied to determine potential impact on structural integrity assessment of a reactor pressure vessel (RPV) under pressurized thermal shock (PTS) transient loading and pressure-temperature (PT) loading produced by reactor heatup and cooldown transients. Biaxial shallow-flaw fracture-toughness tests results were also used to determine the parameter controlling fracture in the transition temperature range, and to develop a related dual-parameter fracture-toughness correlation. Shallow-flaw and biaxial loading effects were found to reduce the conditional probability of crack initiation by a factor of nine when the shallow-flaw fracture-toughness K{sub Jc} data set, with biaxial-loading effects adjustments, was substituted in place of ASME Code K{sub Ic} data set in PTS analyses. Biaxial loading was found to reduce the shallow-flaw fracture toughness of RPV steel such that the lower-bound curve was located between ASME K{sub Ic} and K{sub IR} curves. This is relevant to future development of P-T curve analysis procedures. Fracture in shallow-flaw biaxial samples tested in the lower transition temperature range was shown to be strain controlled. A strain-based dual-parameter fracture-toughness correlation was developed and shown to be capable of predicting the effect of crack-tip constraint on fracture toughness for strain-controlled fracture.
Date: April 1, 1996
Creator: Pennell, W.E.; Bass, B.R.; Bryson, J.W.; Dickson, T.L.; McAfee, W.J. & Merkle, J.G.
Partner: UNT Libraries Government Documents Department

Improvements to mixture level tracking model

Description: The purpose of this paper is to present the results of the testing of the recent improvements made to the two-phase level tracking model in RELAP5/MOD3.2. The level model was originally developed during the development of the TRAC-BWR computer code and was subsequently modified by the Pennsylvania State University (PSU). The modifications developed at PSU concern the way in which the two-phase level is moved from volume to volume as the thermal-hydraulic conditions in the system being simulated change during the course of a transients. The other components in the level tracking model remain as described in the original implementation of the model.
Date: April 1, 1996
Creator: Weaver, W.L.
Partner: UNT Libraries Government Documents Department

Low-density ionization behavior

Description: As part of a continuing study of the physics of matter under extreme conditions, I give some results on matter at extremely low density. In particular I compare a quantum mechanical calculation of the pressure for atomic hydrogen with the corresponding pressure given by Thomas-Fermi theory. (This calculation differs from the ``confined atom`` approximation in a physically significant way.) Since Thomas-Fermi theory in some sense, represents the case of infinite nuclear charge, these cases should represent extremes. Comparison is also made with Saha theory, which considers ionization from a chemical point of view, but is weak on excited-state effects. In this theory, the pressure undergoes rapid variation as electron ionization levels are passed. This effect is in contrast to the smooth behavior of the Thomas-Fermi fixed temperature, complete ionization occurs in the low density limit, I study the case where the temperature goes appropriately to zero with the density. Although considerable modification is required, Saha theory is closer to the actual results for this case than is Thomas-Fermi theory.
Date: April 1, 1995
Creator: Baker, G.A. Jr.
Partner: UNT Libraries Government Documents Department

Quantitative infrared analysis of hydrogen fluoride

Description: This work was performed at the Portsmouth Gaseous Diffusion Plant where hydrogen fluoride is produced upon the hydrolysis of UF{sub 6}. This poses a problem for in this setting and a method for determining the mole percent concentration was desired. HF has been considered to be a non-ideal gas for many years. D. F. Smith utilized complex equations in his HF studies in the 1950s. We have evaluated HF behavior as a function of pressure from three different perspectives. (1) Absorbance at 3877 cm{sup -1} as a function of pressure for 100% HF. (2) Absorbance at 3877 cm{sup -1} as a function of increasing partial pressure HF. Total pressure = 300 mm HgA maintained with nitrogen. (3) Absorbance at 3877 cm{sup -1} for constant partial pressure HF. Total pressure is increased to greater than 800 mm HgA with nitrogen. These experiments have shown that at partial pressures up to 35mm HgA, HIF follows the ideal gas law. The absorbance at 3877 cm{sup -1} can be quantitatively analyzed via infrared methods.
Date: April 1, 1997
Creator: Manuta, D.M.
Partner: UNT Libraries Government Documents Department

A multiaxial viscoplastic model for advanced Si{sub 3}N{sub 4} ceramics

Description: A uniaxial creep/creep rupture model developed previously based on results obtained from uniaxial tensile creep tests of an advanced Si{sub 3}N{sub 4} ceramic has been refined and upgraded in multiaxial form to facilitate general applications. Severity of asymmetric creep behavior in tension compared to that in compression observed in recent experimental results mandates this revision. The tensorial formulation follows the plasticity theories developed for soils. Material sensitivity to pressure, asymmetry between tension and compression, changes of material structure due to hardening of grain boundary phase, and deformation induced volumetric swelling attributable to cavity and void formations have all been considered. Provisions for such features in the proposed multiaxial model are shown to have improved modeling flexibility.
Date: April 1, 1996
Creator: Ding, J.L.; Liu, K.C. & Brinkman, C.R.
Partner: UNT Libraries Government Documents Department

Index of refraction versus oxygen partial pressure for tantalum oxide and silicon dioxide films produced by ion beam deposition

Description: Tantalum oxide and silicon oxide films were made using an ion beam sputtering system. It was found that even though these films were deposited from oxide targets, additions of oxygen were necessary to achieve stoichiometry and hence index of refraction. It was observed that the tantalum oxide target changed color from white to gray, indicating that the oxygen was being depleted from the target. The addition of oxygen to the chamber during deposition replenished the target and improved film stoichiometry. The deposition rate decreased with increasing oxygen partial pressure. It was experimentally determined that by varying the oxygen partial pressure and keeping all other variables fixed, the index of refraction of the film changed in a predictable manner. That is, as the oxygen partial pressure was increased, the index decreased rapidly initially and then reached a saturation point where it stayed fixed with oxygen content. With this data a coating process can be set up using the minimum amount of oxygen (thus increasing filament lifetime) to produce a fully stoichiometric film that has a fixed index. This paper will present the details of these observations and results.
Date: April 30, 1998
Creator: Goward, W.D.; Petersen, H.E.; Dijaili, S.P. & Walker, J.D.
Partner: UNT Libraries Government Documents Department

Achieving improved cycle efficiency via pressure gain combustors

Description: As part of the Department of Energy`s Advanced Gas Turbine Systems Program, an investigation is being performed to evaluate ``pressure gain`` combustion systems for gas turbine applications. This paper presents experimental pressure gain and pollutant emission data from such combustion systems. Numerical predictions for certain combustor geometries are also presented. It is reported that for suitable aerovalved pulse combustor geometries studied experimentally, an overall combustor pressure gain of nearly 1 percent can be achieved. It is also shown that for one combustion system operating under typical gas turbine conditions, NO{sub x} and CO emmissions, are about 30 ppmv and 8 ppmv, respectively.
Date: April 1, 1995
Creator: Gemmen, R.S.; Janus, M.C.; Richards, G.A.; Norton, T.S. & Rogers, W.A.
Partner: UNT Libraries Government Documents Department

Beam tube vacuum in 100 TeV hadron colliders

Description: Bounds on the beam tube gas pressure and the required pumping speed are estimated for {approximately} 2 T low field (LF) and {approximately} 12 T high field (HF) 100 TeV center-of-mass hadron colliders. In both cases photodesorption by synchrotron radiation is the dominant source of gas. Assuming beam-gas scattering limited luminosity lifetime five times the IP scattering lifetime, the required CO equivalent beam tube pressure is 0.25 nTorr for LF and 1.8 nTorr for HF, ambient room temperature equivalent. The CO equivalent pumping speeds required to achieve this pressure within a reasonable beam conditioning time (a few tenths of an operational year at design intensity) are estimated to be {approximately} 300 l/s-m for LF and {approximately} 40 l/s-m for HF. For the LF case with a superferric warm iron magnet, the beam tube is at ambient room temperature and a distributed NEG plus lumped ion or cryo pump system is considered. The size of antechamber needed, ID {approximately} 6 cm, requires that it be located outside the {approximately} 2 cm C-coil magnet gap. Lumped pumps for pumping CH{sub 4} need to be spaced at {approximately} 20 m intervals on the antechamber. For the HF case the likely beam tube temperature is 15--20 K and cryopumping with a beam screen system is considered. The necessary pumping speed can be achieved with slots covering {approximately} 2% of the beam screen surface.
Date: April 1, 1997
Creator: Turner, W.C.
Partner: UNT Libraries Government Documents Department

Observation of Modes at Frequencies Near the Second Alfvin Gap in TFTR

Description: Modes has been observed in the frequency range of the second Alfvenic gap in H-minority ICRF heated plasmas in TFTR. This observation is surprising in that the second gap is generally considered to be small in circular cross section plasmas. The mode is inferred to be a core mode, i.e., localized in some sense within the q=1 surface. This follows from the observation that the time dependence of the mode frequency is consistent with the changes in the central density, with the appearance of the mode in the latter part of the sawtooth period when the central fast ion beta has peaked up, and with the direction of propagation, the last of these being explained by a hollow first ion beta profile, which is only present in the core region. The modes are generally not observed during on-axis H-minority heating, but commonly observed during off-axis heating on the high field side (with the resonant layer outside the q=1 surface). A model has been proposed that the beta of the fast ions opens the second gap, allowing instability. For TFTR parameters, the model predicts a gap width of approximately 10 kHz, which is 2.5% of the second gap frequency. If the backwards mode propagation is due to a hollow fast ion profile (as indicated in the TRANSP calculations), then instability due to wave-particle resonance at the magnetic curvature precessional frequency can occur only if the precessional frequency is reversed--which can indeed be the case for off-axis heating on the high field side. Thus, trapped fast ion pressure effects seem to explain several of the observed features of these second gap fluctuations.
Date: April 1, 1999
Creator: E., Fredrickson.; Van Dam, J.W.; Budny, R.V.; Darrow, D.; Fu, G.Y.; Hosea, J. et al.
Partner: UNT Libraries Government Documents Department

Threshold velocity for environmentally-assisted cracking in low alloy steels

Description: Environmentally Assisted Cracking (EAC) in low alloy steels is generally believed to be activated by dissolution of MnS inclusions at the crack tip in high temperature LWR environments. EAC is the increase of fatigue crack growth rate of up to 40 to 100 times the rate in air that occurs in high temperature LWR environments. A steady state theory developed by Combrade, suggested that EAC will initiate only above a critical crack velocity and cease below this same velocity. A range of about twenty in critical crack tip velocities was invoked by Combrade, et al., to describe data available at that time. This range was attributed to exposure of additional sulfides above and below the crack plane. However, direct measurements of exposed sulfide densities on cracked specimens were performed herein and the results rule out significant additional sulfide exposure as a plausible explanation. Alternatively, it is proposed herein that localized EAC starting at large sulfide clusters reduces the calculated threshold velocity from the value predicted for a uniform distribution of sulfides. Calculations are compared with experimental results where the threshold velocity has been measured, and the predicted wide range of threshold values for steels of similar sulfur content but varying sulfide morphology is observed. The threshold velocity decreases with the increasing maximum sulfide particle size, qualitatively consistent with the theory. The calculation provides a basis for a conservative minimum velocity threshold tied directly to the steel sulfur level, in cases where no details of sulfide distribution are known.
Date: April 1, 1997
Creator: Wire, G.L. & Kandra, J.T.
Partner: UNT Libraries Government Documents Department

Testing of a steel containment vessel model

Description: A mixed-scale containment vessel model, with 1:10 in containment geometry and 1:4 in shell thickness, was fabricated to represent an improved, boiling water reactor (BWR) Mark II containment vessel. A contact structure, installed over the model and separated at a nominally uniform distance from it, provided a simplified representation of a reactor shield building in the actual plant. This paper describes the pretest preparations and the conduct of the high pressure test of the model performed on December 11-12, 1996. 4 refs., 2 figs.
Date: April 1, 1997
Creator: Luk, V. K.; Hessheimer, M. F.; Matsumoto, T.; Komine, K. & Costello, J. F.
Partner: UNT Libraries Government Documents Department

Characterization of phosphorus segregation in neutron-irradiated pressure vessel steels by atom probe field ion microscopy

Description: An atom probe field ion microscopy characterization of A533B and Russian VVER 440 and 1000 pressure vessel steels has been performed to determine the phosphorus coverage of grain and lath boundaries. Field ion micrographs of grain and lath boundaries have revealed that they are decorated with a semi-continuous film of discrete brightly-imaging precipitates that were identified as molybdenum carbonitride precipitates. In addition, extremely high phosphorus levels were measured at the boundaries. The phosphorus segregation was found to be confined to an extremely narrow region indicative of monolayer-type segregation. The phosphorus coverages determined from the atom probe results of the unirradiated materials were in excellent agreement with predictions based on McLean`s equilibrium model of grain boundary segregation. The boundary phosphorus coverage of a neutron-irradiated weld material was significantly higher than that observed in the unirradiated material.
Date: April 1995
Creator: Miller, M. K.; Jayaram, R. & Russell, K. F.
Partner: UNT Libraries Government Documents Department

Fracture behavior of shallow cracks in full-thickness clad beams from an RPV wall section

Description: A testing program is described that utilizes full-thickness clad beam specimens to quantify fracture toughness for shallow cracks in weld material for which metallurgical conditions are prototypic of those found in reactor pressure vessels (RPVs). The beam specimens are fabricated from an RPV shell segment that includes weld, plate and clad material. Metallurgical factors potentially influencing fracture toughness for shallow cracks in the beam specimens include material gradients and material inhomogeneities in welded regions. The shallow-crack clad beam specimens showed a significant loss of constraint similar to that of other shallow-crack single-edge notch bend (SENB) specimens. The stress-based Dodds-Anderson scaling model appears to be effective in adjusting the test data to account for in-plane loss of constraint for uniaxially tested beams, but cannot predict the observed effects of out-of-plane biaxial loading on shallow-crack fracture toughness. A strain-based dual-parameter fracture toughness correlation (based on plastic zone width) performed acceptably when applied to the uniaxial and biaxial shallow-crack fracture toughness data.
Date: April 1, 1995
Creator: Keeney, J. A.; Bass, B. R. & McAfee, W. J.
Partner: UNT Libraries Government Documents Department

Residual stresses in weld deposited clad pressure vessels and nozzles

Description: Results of through-thickness residual stress measurements are provided for a variety of samples of weld deposited 308/309L stainless steel and Alloy 600 cladding on low-alloy pressure vessel ferritic steels. Clad thicknesses between 5 and 9mm on samples that vary in thickness from 45 to 200mm were studied. The samples were taken from flat plates, from a spherical head of a pressure vessel, from a ring-segment of a nozzle bore, and from the transition radius between a nozzle and a pressure vessel shell. A layer removal method was used to measure the residual stresses. The effects of uncertainties in elastic constants (Young`s modulus and Poisson`s ratio) as well as experimental error are assessed. All measurements were done at room temperature. The results of this work indicate that curvature plays a significant role in cladding residual stress and that tensile residual stresses as high as the yield stress can be measured in the cladding material. Since the vessel from which the spherical and nozzle corner samples were taken was hydrotested, and the flat plate specimens were taken from specimens used in mechanical fatigue testing, these results suggest that rather high tensile residual stresses can be retained in the cladding material even after some mechanical loading associated with hydrotesting and that higher levels of hydrotest loading would be required to alter the cladding residual stresses.
Date: April 1, 1998
Creator: Jones, D.P.; Mabe, W.R.; Shadley, J.R. & Rybicki, E.F.
Partner: UNT Libraries Government Documents Department

Oxidation performance of V-Cr-Ti alloys

Description: Vanadium-base alloys are being considered as candidates for the first wall in advanced V-Li blanket concepts in fusion reactor systems. However, a primary deterrent to the use of these alloys at elevated temperatures is their relatively high affinity for interstitial impurities, i.e., O, N, H, and C. The authors conducted a systematic study to determine the effects of time, temperature, and oxygen partial pressure (pO{sub 2}) in the exposure environment on O uptake, scaling kinetics, and scale microstructure in V-(4--5) wt.% Cr-(4--5) wt.% Ti alloys. Oxidation experiments were conducted on the alloys at pO{sub 2} in the range of 5 x 10{sup {minus}6}-760 torr (6.6 x 10{sup {minus}4}-1 x 10{sup 5} Pa) at several temperatures in the range of 350--700 C. Models that describe the oxidation kinetics, oxide type and thickness, alloy grain size, and depth of O diffusion in the substrate of the two alloys were determined and compared. Weight change data were correlated with time by a parabolic relationship. The parabolic rate constant was calculated for various exposure conditions and the temperature dependence of the constant was described by an Arrhenius relationship. The results showed that the activation energy for the oxidation process is fairly constant at pO{sub 2} levels in the range of 5 x 10{sup {minus}6}-0.1 torr. The activation energy calculated from data obtained in the air tests was significantly lower, whereas that obtained in pure-O tests (at 760 torr) was substantially higher than the energy obtained under low-pO{sub 2} conditions. The oxide VO{sub 2} was the predominant phase that formed in both alloys when exposed to pO{sub 2} levels of 6.6 x 10{sup {minus}4} to 0.1 torr. V{sub 2}O{sub 5} was the primary phase in specimens exposed to air and to pure O{sub 2} at 760 torr. The implications of the increased O concentration are ...
Date: April 3, 2000
Creator: Natesan, K. & Uz, M.
Partner: UNT Libraries Government Documents Department

Emergency destruction system for recovered chemical munitions

Description: At the request of the US Army Project Manager for Non-Stockpile Chemical Materiel, Sandia National Laboratories is developing a transportable system for destroying recovered, explosively configured, chemical warfare munitions. The system uses shaped charges to access the agent and burster followed by chemical neutralization to destroy them. The entire process takes place inside a sealed pressure vessel. In this paper, they review the design, operation, and testing of a prototype system capable of containing up to one pound of explosive.
Date: April 1, 1998
Creator: Shepodd, T.J.; Stofleth, J.H. & Haroldsen, B.L.
Partner: UNT Libraries Government Documents Department

Insentropic compression of solid using pulsed magnetic loading

Description: Shock loading techniques are often used to determine material response along a specific pressure loading curve referred to as the Hugoniot. However, many technological and scientific applications require accurate determination of dynamic material response that is off-Hugoniot, covering large regions of the equation-of-state surface. Unloading measurements from the shocked state provide off-Hugoniot information, but experimental techniques for measuring compressive off-Hugoniot response have been limited. A new pulsed magnetic loading technique is presented which provides previously unavailable information on isentropic loading of materials to pressures of several hundred kbar. This smoothly increasing pressure loading provides a good approximation to the high-pressure material isentrope centered at ambient conditions. The approach uses high current densities to create ramped magnetic loading to a few hundred kbar over time intervals of 100--200 ns. The method has successfully determined the isentropic mechanical response of copper to about 200 kbar and has been used to evaluate the kinetics of the alpha-epsilon phase transition occurring in iron at 130 kbar. With refinements in progress, the method shows promise for performing isentropic compression experiments to multi-Mbar pressures.
Date: April 18, 2000
Creator: HALL,CLINT A.; ASAY,JAMES R.; STYGAR,WILLIAM A.; SPIELMAN,RICK B.; ROSENTHAL,STEPHEN E.; KNUDSON,MARCUS D. et al.
Partner: UNT Libraries Government Documents Department

Horizontal Axis Wind Turbine Aerodynamics: Three-Dimensional, Unsteady, and Separated Flow Influences

Description: Surface pressure data from the National Renewable Energy Laboratory's ''Unsteady Aerodynamics Experiment'' were analyzed to characterize the impact of three-dimensionality, unsteadiness, and flow separation effects observed to occur on downwind horizontal axis wind turbines (HAWT). Surface pressure and strain gage data were collected from two rectangular planform blades with S809 airfoil cross-sections, one flat and one twisted. Both blades were characterized by the maximum leading edge suction pressure and by the azimuth, velocity, and yaw at which it occurred. The occurrence of dynamic stall at all but the inboard station (30% span) shows good quantitative agreement with the theoretical limits on inflow velocity and yaw that should yield dynamic stall events. A full three-dimensional characterization of the surface pressure topographies combined with flow visualization data from surface mounted tufts offer key insights into the three-dimensional processes involved in the unsteady separation process and may help to explain the discrepancies observed with force measurements at 30% span. The results suggest that quasi-static separation and dynamic stall analysis methods relying on purely two-dimensional flow characterizations may not be capable of simulating the complex three-dimensional flows observed with these data.
Date: April 5, 1999
Creator: Robinson, M. C.; Hand, M. M.; Simms, D. A. & Schreck, S. J.
Partner: UNT Libraries Government Documents Department

Fatigue crack growth testing of sub-clad defects

Description: Fatigue crack growth tests were performed on four point bend specimens with crack like defects intentionally placed in A302B low-alloy pressure vessel steel clad with 308/309L weld deposited stainless steel. The defects were placed in the base metal under the cladding by machining a cavity from the side opposite the cladding, electric-discharge machining a very sharp flaw, fatigue pre-cracking the flaw, and then filling up the cavity by a weld repair process. The specimens were stress relieved before fatigue testing. The specimens were fatigue cycled at positive load ratios until the defects broke through to the surface. The specimens were then fractured at liquid nitrogen temperatures to reveal the fracture surfaces. Seven different sub-clad flaw specimens were tested in room temperature air and each test provides a record of cycles to defect break-through. Changes in defect size and shape as a function of applied load cycles were obtained by benchmarking the crack at various stages of the load history. The results provide a set of embedded defect data which can be used for qualifying fatigue crack growth analysis procedures such as those in Section XI of the ASME Boiler and Pressure Vessel Code. A comparison between calculated and measured values shows that the ASME B and PV Section XI fatigue crack growth procedures conservatively predict cycles to defect break-through for small sub-clad defects.
Date: April 1, 1998
Creator: Jones, D.P. & Leax, T.R.
Partner: UNT Libraries Government Documents Department

An instrument for gravimetric calibration of flow devices with corrosive gases

Description: An instrument was developed for the calibration of mass flow controllers primarily used in the production of semiconductor wafers. Almost all other types of such calibrators require measurement of temperature, pressure and volume. This instrument measures the weight of gas collected in a container and makes measuring those thermodynamic variables unnecessary. The need to measure the weight of the gas container is eliminated by submerging it in a liquid (presently water) and balancing its weight with the force of buoyancy. The accuracy of this Gravimetric Calibrator is unaffected by the pressure and temperature of the gas. The Calibrator can also measure reactive, corrosive, and non-ideal gases. The container remains connected to the process by a torsion capillary, and a load cell measures the changing gas weight continuously throughout the measuring process. A prototype was designed for gas flows ranging from 1 sccm of hydrogen to 10,000 sccm of tungsten hexafluoride, constructed, tested, and used to calibrate flow devices. Experience with the prototype and results are presented, and plans for further developments are discussed. Design of a version for the flow range from 0.1 sccm to 100 sccm is in progress.
Date: April 1995
Creator: Remenyik, C. J. & Hylton, J. O.
Partner: UNT Libraries Government Documents Department

Preliminary results of steel containment vessel model test

Description: A high pressure test of a mixed-scaled model (1:10 in geometry and 1:4 in shell thickness) of a steel containment vessel (SCV), representing an improved boiling water reactor (BWR) Mark II containment, was conducted on December 11-12, 1996 at Sandia National Laboratories. This paper describes the preliminary results of the high pressure test. In addition, the preliminary post-test measurement data and the preliminary comparison of test data with pretest analysis predictions are also presented.
Date: April 1, 1997
Creator: Matsumoto, T.; Komine, K. & Arai, S.
Partner: UNT Libraries Government Documents Department