bluuebunny/crossref_metadata_2025_split huggingface dataset:
Use of a Constant ΔK Test Method in the Investigation of Fatigue Crack Growth in 288°C Water Environments
Authors: Van Der Sluys WA , DeMiglio DS 
Published: December 2008

To characterize environmental fatigue crack growth properties of reactor pressure vessel steels, experiments were conducted by a computer-controlled constant alternating stress intensity factor (ΔK) test technique over a wide range of R-ratios and loading frequencies in 288°C water environments. Compact fracture specimens of two nuclear pressure vessel steels were tested over a range of ΔK-values from 16 to 55 MPa √m. Loading frequencies ranged from 0.0017 to 10 Hz, and R-ratios from 0.16 to 0.72.
As many as 22 separate experiments were conducted on a single specimen. The constant ΔK test method permitted crack growth rate measurements to be made with a high degree of confidence over long intervals of crack extension.
A simulated pressurized water reactor (PWR) environment plays only a minor role in the enhancement of fatigue crack growth rates. The applied ΔK was the primary rate-controlling variable, while R-ratio and loading frequency were secondary.
In high-purity deoxygenated water, the environment had a very significant effect on crack growth rates. The loading frequency was a primary rate-controlling variable at low loading frequencies. At high loading frequencies crack growth rates were ΔK-dependent.
Effect of Water Vapor on Fatigue Crack Growth in 7475-T651 Aluminum Alloy Plate
Authors: Dicus DL 
Published: December 2008

An investigation was performed to assess the effects of water vapor on fatigue crack growth in 7475-T651 aluminum alloy plate at frequencies of 1 and 10 Hz. Twenty-five mm thick compact specimens were subjected to constant amplitude fatigue testing at a load ratio of 0.2. Fatigue crack growth rates were calculated from effective crack lengths determined by using a compliance method. Tests were conducted in hard vacuum and at water vapor partial pressures ranging from 94 Pa to 3.8 kPa.
Fatigue crack growth rates were frequency-insensitive under all environmental conditions tested. For constant stress intensity factor ranges, crack growth rate transitions occurred at low and high water vapor pressures. Crack growth rates at intermediate pressures were relatively constant and showed reasonable agreement with published data for two Al-Cu-Mg alloys. The existence of two crack growth rate transitions suggests either a change in rate-controlling kinetics or a change in corrosion fatigue mechanism as a function of water vapor pressure. Reduced residual deformation and transverse cracking on specimens tested in water vapor versus vacuum may be evidence of embrittlement within the plastic zone due to environmental interaction.
Characteristics of Hydrostatically Extruded Zr-2.5Nb Alloy
Authors: Jie Z , Zhenhe L , Wenxian H , Yunxia Z , Jiaqi D , Yan L , Tieqi Y 
Published: December 2008

Hydrostatic extrusion is a new production technology. Zr-2.5Nb alloy tubes cold hydrostatically extruded possess excellent mechanical properties similar to heat-treated tubes and better than cold-worked tubes. Examination by transmission electron microscope shows that the alloy is of a uniform cell substructure containing the (α + β) phases, which is one of important factors improving properties of the alloy.
The study of texture, stress, and reorientation of the hydride shows that hydrostatically extruded tubes with basal plane normals in the radial direction have obviously higher hydride reorientation threshold stress than tubes with basal plane normals in the circumferential direction.
Moreover, investigation of fracture toughness reveals that hydride distributed perpendicular to the crack propagation direction restrains further propagation of the crack. It is favorable for preserving the fracture resistance of the material.
Pressure Tube Development for CANDU Reactors
Authors: Fleck RG , Price EG , Cheadle BA 
Published: December 2008

A development program is described in which reactor grade Zr-2.5Nb pressure tubes were produced with properties comparable to current reactor tubes but which are expected to show lower in-reactor creep and growth. Lower creep and growth rates would mean smaller axial elongations of tubes in service.
Evaluation of the tubes showed that they met the specification requirements and compared favorably with tubes produced by the current route. Early in-reactor creep tests suggest that the development tubes will exhibit similar diametral creep behavior to current tubes. In-reactor growth tests have not yet reached steady-state behavior. The properties and possible reasons for the behavior are reported and discussed.
Estimation of Conservatism of Present Embrittlement Criteria for Zircaloy Fuel Cladding Under LOCA
Authors: Furuta T , Uetsuka H , Kawasaki S 
Published: December 2008

To estimate the degree of conservatism of the present embrittlement criteria, the following examinations have been conducted. Zircaloy-4 tubes were oxidized at temperatures ranging from 1173 to 1573 K, and then compressed at 373 K to determine the embrittlement due to oxygen absorption. The simulated Zircaloy-clad fuel rods were burst and oxidized in steam at temperatures within the range 1200 to 1500 K. The segment sectioned from each burst cladding was also compressed to determine the effect of hydrogen absorption on cladding embrittlement. The results obtained from these experiments have revealed that the additional embrittlement due to hydrogen absorption is found to be significant in burst cladding.The simulated Zircaloy clad fuel rods were burst and exposed to steam at isothermal temperatures ranging from 1173 to 1573 K and then bottom-flooded at the oxidation temperature or 773 K with water, after the specimen was restrained at the end of exposure time. The specimens were also bottom-flooded under a nonrestrained condition to determine the effect of restraining stress on thermal-shock-failure characteristics. The presence of restraining stress limits the permissible oxidation condition to lower temperature and shorter exposure time. Even the estimated thermal-shock-failure boundary under a restrained condition is located above the 15% oxidation line which is adopted by the present criteria.
Out-of-Pile Experiments on the High-Temperature Behavior of Zircaloy-4 Clad Fuel Rods
Authors: Hagen S 
Published: December 2008

Out-of-pile experiments have been performed to investigate the escalation in temperature of Zircaloy-clad fuel rods during heatup in steam due to the exothermal Zircaloy steam reaction. In these tests single Zircaloy/uranium dioxide (UO2) fuel rod simulators surrounded with a Zircaloy shroud—simulating the Zircaloy of neighboring rods—were heated inside a fiber ceramic insulation. The initial heating rates were varied from 0.3 to 2.5 K/s.
In every test an escalation of the temperature rise rate was observed. The maximum measured surface temperature was about 2200°C. The temperature decreased after the maximum had been reached without decreasing the input electric power. The temperature decreases were due to inherent processes including the runoff of molten Zircaloy. The escalation process was influenced by the temperature behavior of the shroud, which was itself affected by the insulation and steam cooling.
Damage to the fuel rods increased with increasing heatup rate. For slow heatup rates nearly no interaction between the oxidized cladding and UO2 was observed, while for fast heatup rates the entire annular pellet was dissolved by molten Zircaloy.
Physical and Chemical Phenomena Associated with the Dissolution of Solid UO2 by Molten Zircaloy-4
Authors: Hofmann P , Kerwin-Peck D , Nikolopoulos P 
Published: December 2008

Laboratory experiments were performed in the temperature range 1800 to 2000°C in inert gas to study the chemical interaction between solid uranium dioxide (UO2) and liquid Zircaloy-4, and the wettability of UO2 by molten Zircaloy as functions of time and Zircaloy oxygen concentration. The experiments were interrupted after various reaction times to determine the extent of the chemical interaction and of the UO2 dissolution. The results show that the dissolution of UO2 by molten Zircaloy is primarily a chemical process, and that the extent of the interaction depends on the wettability of UO2 by molten Zircaloy. The wettability, however, depends strongly on the oxygen content of the Zircaloy and therefore on the time of UO2/Zircaloy contact. The wettability improves with increasing oxygen content. Zircaloy reduces UO2 to form a homogeneous [uranium, zirconium, oxygen (U,Zr,O)] melt at low oxygen concentrations or a heterogeneous (U,Zr,O) melt which contains (U,Zr)O2 particles at high oxygen concentrations. During cooling, the (U,Zr,O) melt decomposes into a (U,Zr) alloy with high uranium content and oxygen-stabilized α-Zr(O).
The amount of fuel which can be liquefied by molten cladding depends on the initial oxygen content of the melt. Oxygen-free liquid Zircaloy can dissolve considerably more UO2 than Zircaloy rich in oxygen.
The significance of these experiments is that UO2 fuel can be “liquefied” by molten Zircaloy far below the melting point of UO2.
Elastic-Plastic Properties of Submerged Arc Weld Metal
Authors: Van Der Sluys WA , Emanuelson RH , Futato RJ 
Published: December 2008

The results of a study conducted over a number of years to characterize the elastic-plastic fracture properties of submerged arc weld metal are presented in this paper. The fracture properties of four different weldments were investigated at temperatures ranging from 24 to 288°C (75 to 550°F). Tests were conducted using both the conventional multiple-specimen JIc procedure as well as an automated single-specimen unloading compliance technique capable of generating the material JI-R curve.
Test results obtained using the two different procedures are compared. The comparison indicates that while both test techniques generate comparable J-Δa data for a given test condition, JIc values from the respective sets of data can differ. This is attributed largely to the sparsity of data generated by the multiple-specimen technique and the nonlinearity of the JI-R curves as revealed by the single-specimen technique.
Welding procedure was found to have a significant effect on measured toughness. A wide range of fracture behavior was observed. The welding parameters responsible for the observed behavior are discussed. The applicability of the current JIc and JI-R curve test procedures over the wide range of crack growth behavior observed is discussed.
Some Observations on J-R Curves
Authors: Gibson GP , Druce SG 
Published: December 2008

The effect of specimen size and geometry on the onset of ductile tearing (Ji, δi) and the initial slope of J(dJ/da) and crack opening displacement dδ/da resistance curves has been investigated for a carbon-manganese steel. The results indicate that in plane sided specimens a thickness in excess of that specified in ASTM Test for JIc, a Measure of Fracture Toughness (E 813) is required to achieve a lower bound, or plane strain, Ji value. However, the resultant decrease in Ji is relatively small. Side-grooving was found to be very effective in promoting plane strain conditions in subsized specimens. The initial tearing resistance was found to be markedly influenced by specimen thickness and degree of side-grooving, and the results indicate that achieving plane strain conditions in the proximity of the crack tip does not ensure a unique J-R curve in side-grooved specimens.
JIc values obtained using ASTM E 813 were found to overestimate the “true” Ji values for a carbon-managanese steel and a pressure vessel steel. This arises from the linear representation of the R curve and the assumed blunting line behavior A power law equation was found to give a statistically better fit to the J-Δa data, particularly in high toughness materials. The need for an engineering or working definition of ductile crack initiation for structural assessment has been acknowledged, and an alternative to the ASTM E 813 procedure suggested, based on the J value at 0.2 mm of crack extension.
Comparison of Potential Drop and Unloading Compliance Methods in Determining Ductile Crack Extension
Authors: Wallin K , Saario T , Auerkari P , Saarelma H , Torronen K 
Published: December 2008

Two different methods, the unloading compliance and the AC-potential drop method have been applied simultaneously for crack length measurement during ductile crack extension in J-R curve determinations. The materials used in the comparison of the two test methods were a pressure vessel steel A533B C1.1 (Unified Numbering System [UNI] K12539), a comparable weldment, and a carbon-manganese steel OX522D weld. Specimen geometries used were 25-mm compact tension (ITCT) and 15-mm three-point bend (3PB), respectively.
The two methods applied give consistent results for the amount of crack extension. However, the location of the potential minimum is dependent upon material, specimen geometry, temperature, frequency and current. This leads to the conclusion that the ACPD method fails to indicate the initiation of ductile crack extension correctly. Reasons for this are discussed.
Slurry Cutoff Walls: Applications in the Control of Hazardous Wastes
Authors: Ryan CR 
Published: December 2008

Slurry cutoff walls are nonstructural barriers constructed to intercept and impede the flow of fluids underground. There are two basic types of slurry cutoff walls, soil-bentonite (SB) and cement-bentonite (CB). Depending on the nature of the project, either method may have some technical or economic advantage over the other. In both cases, a narrow trench is excavated into the ground using a backhoe or other more specialized equipment. The trench is prevented from collapsing by keeping it full at all times with bentonite slurry similar to drilling mud. In the case of SB walls, the trench is subsequently backfilled with a mixture of soil and bentonite slurry that forms the permanent impervious cutoff wall. With the CB method, cement is added to the slurry, which later sets up, forming the permanent seepage barrier.
Slurry cutoff walls are being used in an increasing variety of applications to provide a barrier to the lateral underground flow of various fluids. Principal applications are site dewatering, underground pollution control, and seepage barriers under dams. In this paper, case studies are used to provide examples of recent applications in the control of leaching hazardous wastes.
Projects cited include:
1. Containment of oil seeping through a reservoir abutment.
2. Cleanup of a polychlorinated biphenyl (PCB) contaminated site.
3. Containment of leachates and methane gas migration from a sanitary landfill site.
4. Cleanup of a site with spilled phenols.
All of the examples were selected because of the unusual conditions under which they were constructed or because of the dramatic evidence of results.
Thin Slurry Cutoff Walls Installed by the Vibrated Beam Method
Authors: Leonards GA , Schmednecht F , Chameau J-L , Diamond S 
Published: December 2008

In recent years, thin slurry walls installed by vibrating a beam into the ground and injecting a suitable slurry as it is withdrawn have been used successfully and economically in a variety of applications, most notably as (a) permanent seepage cutoffs either in new or existing dams or levees, (b) a means of temporarily controlling groundwater during construction, and (c) a device for containment of toxic wastes.
This paper describes the equipment and construction techniques for installing the cut-off, and details of various types of slurries suitable for different applications are given. The results of field investigations undertaken to assess the permeability and continuity of vertical and battered (inclined) slurry walls are presented.
Influence of Inorganic Permeants upon the Permeability of Bentonite
Authors: Alther G , Evans JC , Fang H-Y , Witmer K 
Published: December 2008

A total of 16 inorganic aqueous solutions were utilized as permeants to determine their effects upon the permeability of both contaminant resistant (polymerized) bentonite and untreated bentonite. It was found that, of the aqueous solutions tested, those with potassium (K+) cations or chloride (Cl−) anions or both induced the largest permeability increases with increasing electrolyte concentration. Conversely, solutions with sodium (Na+) cations or carbonate (CO−3) anions had the least impact upon the permeability of bentonite. It was also observed that doubly charged cations (+2) have a greater initial effect on the permeability than do singly charged cations (+1). Furthermore, a “saturation limit” was in evidence for +2 cations, indicating that beyond certain concentrations the further addition of the soluble salts had only limited additional impact upon the permeability.
For selected bentonite-contaminant combinations, slurry cracking pattern tests were conducted. A correlation between the permeability changes and the results of the cracking pattern tests was demonstrated.
Based upon the findings of this study, it is concluded that the character of the solute anions, as well as the primary cations, affect the permeability of bentonite clays. Further, the Gouy-Chapman model of diffuse double layer was found to be generally consistent with the test data.
Effects of Various Liquids on Clay Soil: Bentonite Slurry Mixtures
Authors: Anderson DC , Crawley W , Zabcik JD 
Published: December 2008

Slurry-wall backfill materials were placed in double-ring permeameters to evaluate their permeability to water, xylene, and methanol. Permeability determinations were made using double-ring permeameters because these devices separate flow that occurs near the sidewalls from flow occurring through the central portion of the specimens. The use of double-ring devices appears to overcome some of the limitations of fixed-wall and flexible-wall permeameters. Fixed-wall devices may have sidewall flow, and flexible-wall devices may be inappropriate for testing soft specimens such as a slurry mixture.
Permeability tests on materials that are to contain waste leachates are typically done using water [0.01 N calcium sulfate (CaSO4)] as the permeant liquid. The results of this study show that permeability values determined with water may be misleading. Low permeabilities were obtained with water, but both xylene and methanol caused large permeability increases in the soil-slurry mixtures.
Procedure and Equipment Factors Affecting Permeability Testing of a Bentonite-Sand Liner Material
Authors: Edil TB , Erickson AE 
Published: December 2008

This paper presents the findings of an investigation regarding the effects of procedural and equipmental factors on the laboratory measurement of permeability of a bentonite-sand liner. In the experimental program, permeability tests were performed on compacted specimens of a bentonite-sand mixture to study the effect of (1) permeameter type (rigid- versus flexible-wall permeameters), (2) back pressure application, and (3) hydraulic gradient magnitude on the measured permeabilities. The liner material used in the tests was a mixture of 90% P20–R30 Ottawa sand and 10% bentonite clay. Water was used to prepare the specimens and as the permeant. Specimens were prepared by compaction at moisture contents exceeding optimum using the standard proctor method. A pressure of 380 kPa was used in the tests involving back pressure. The low and high hydraulic gradients used were nominally 29 and 290, respectively. Prior to the termination of a test, a red indicator was passed through the permeameters under the high gradient. The specimens were dissected and inspected after the test for the identification of flow areas and channels.
The test results indicated that specimens continue to hydrate during permeation. Unless wetter specimens are used, this continuing hydration interferes with the inflow-outflow balance, depriving the tester of an important check for leaks. Differential hydration throughout the specimen results in different soil structures and zones of flow. For instance, most of the flow may take place in an annular area surrounding a less hydrated core in the center. Since the total cross-sectional area is used in computing the coefficient of permeability, the values may be underestimated. Back pressure, often used to enhance saturation during testing, appears to have a detrimental effect when applied in the rigid-wall permeameters by increasing the potential for formation of channels and side flow. Test results are affected by hydraulic gradient in different ways depending on the type of permeameter. While gradients as high as 360 did not induce piping in the gap-graded liner material tested, the application of very high gradients to accelerate testing is not desirable for a number of other effects observed.
Permeability of Fly Ash and Fly Ash-Sand Mixtures
Authors: Vesperman KD , Edil TB , Berthouex PM 
Published: December 2008

In an experimental program aimed at evaluating the potential of fly ash for use in liners, permeability tests were performed on two pozzolanic fly ashes from western U.S. coal sources compacted at varying densities and mixed in varying percentages with a quartz sand. Permeability testing was performed in a falling head, flexible membrane, triaxial cell permeameter. A back pressure of 380 kPa and a hydraulic gradient of 10 to 20 were applied to the permeability specimens.
The two pozzolanic fly ashes exhibit different degrees of “self-cementation,” which causes a dramatic influence on the resulting permeability values. The highly self-cementing fly ash exhibits nearly a full three orders of magnitude lower permeability than the less self-cementing fly ash. Increasing density, while not as important as the coal source, decreases permeability in both types of fly ash on the order of about half a magnitude. Moisture content is also an important factor since it controls the extent of cementation as well as compaction density. Increasing percentages of fly ash in the mixtures decreases the permeability up to a limiting value when the volume of fly ash and water added exceeds the available pore space between the sand grains; for instance, the mixture of 40% self-cementing fly ash and 60% sand exhibits essentially the same permeability as the 100% fly ash specimen.
The study indicates that the addition of pozzolanic fly ash to an otherwise highly permeable soil results in a dramatic reduction in permeability. The “self-cementing” fly ash exhibits 103 to 104 folds of permeability reduction with final permeabilities of less than 10−6 mm/s and seems quite suitable for liner applications.
Root-Mean-Square Vertical Acceleration as a Summary Roughness Statistic
Authors: Hudson WR , Halbach D , Zaniewski JP , Moser L 
Published: December 2008

Much has been done in recent years to relate various roughness statistics to rider comfort in terms of a serviceability index (developed by Carey and Irick). Much less has been done on correct evaluation of a true profile in terms of summary statistics for field comparison of vehicle operating costs and user comfort. Important work in this area has been done by Gillespie and Sayers at the University of Michigan, and additional work has been done by Hudson, Williamson, and McKenzie at the University of Texas. Work has also been done in Brazil by Queiroz and others. At least two statistics have been offered for summarizing roughness information:
(a) the average rectified velocity, by Gillespie and Sayers, and
(b) the root-mean-square vertical acceleration, by Hudson et al.
The purpose of this paper is to examine and compare these statistics with particular emphasis on their potential effects on rider comfort and their use as standard calibration statistics for response-type road roughness meters.
A complete parameter study is reported comparing these two statistics. The results of the study will be helpful in selecting useful analytical techniques for routine applications.