bluuebunny/crossref_metadata_2025 huggingface dataset:
Laboratory Studies on Oil Spill Dispersants
Authors: Fingas MF , Dufort VM , Hughes KA , Bobra MA , Duggan LV
Published: December 2008

Laboratory tests of oil spill dispersant effectiveness are used around the world to select dispersants for application to specific oils. These tests are presumed, by some, to represent real sea conditions and to provide the user with a result that is representative if not identical to a real dispersant application at sea. A number of tests have been developed over the years. At this time, the two most widely used tests are the Mackay test, otherwise known as the Mackay-Nadeau-Steelman (MNS) test, and the Labofina test, otherwise known as the Warren Springs or rotating flask test. The Mackay test employs a high velocity air stream to energize 6 L of water, whereas the Labofina test uses rotation of a separatory funnel with 250 mL of water. Both tests apply a large amount of energy to the oil/water system.

This paper compares test results from these apparatus with those from two lesser known devices, the oscillating hoop and the swirling flask. Both devices are relatively new, and protocols for their use have not been finalized. The oscillating hoop apparatus uses a hoop which is moved up and down at the water surface. The concentric waves serve both to energize the oil in the hoop and to contain it. Thirty-five litres of water are used in this test. The swirling flask test makes use of a 125-mL Erlenmeyer flask. The flask is rotated using a standard chemical/biological shaker to produce a swirling motion in the contents.

The results obtained using all 4 apparatus with a number of oils and dispersants are presented. A total of 121 oil/dispersant combinations were tested in the 4 apparatus.

The correlation of numeric values between the Mackay, Labofina, oscillating hoop, and swirling flask is low. The correlation of effectiveness ranking is also poor. An oil that disperses more readily than another, according to one test, is less readily dispersable according to one or more of the other tests. Similarly, a dispersant that is more effective by one test is less effective by another. The results from the oscillating hoop correlate poorly with all other test results.

Specific tests were also conducted to ascertain the effect of settling or rising time (the time the oil-in-water mixture is allowed to sit unagitated before a sample is taken). Longer settling times alter the oscillating hoop test results dramatically, improve the correlation for results with different apparatus, and enhance correlation with physical data such as viscosity. Differences in the effectiveness results are still apparent.

Results show that all the high energy tests (the Mackay, the Labofina and the oscillating hoop) produce unique dispersant effectiveness results and those correlate poorly with the physical properties of the oil.
Design and Evaluation of a Large Boat-Mounted Dispersant Spraying System and Its Integration with Other Application Equipment
Authors: Onstad LA , Lindblom GP
Published: December 2008

Oil spill response groups have recognized that it is essential to have the ability to apply dispersants properly when they are needed. Some of these organizations have developed unique application equipment as part of their total capability. Two California industry cooperatives have designed dispersant spray systems that are attached to existing advancing recovery devices, thus providing the largest spray systems yet developed for any surface vessels.

Detailed calibration of the systems has been done and has provided tables and charts which can be used by both management and operators for direction of dispersant application programs. Close control of dispersant dosage is a requirement for successful dispersant application and also for accurate documentation for regulatory authorities. The calibration work reported here has also shown the variability that can be found in very similar systems and indicated the need for careful evaluation of educator performance, as well as the value of use of accurate metering pumps for dispersant, whether used diluted or undiluted.
Hydrocarbon-Type Analysis of Jet Fuel with Gas Chromatography/Mass Spectrometry
Authors: Gehron MJ , Yost RA
Published: December 2008

A gas chromatography/mass spectrometry hydrocarbon-type analysis (GC/MS/HTA) method has been developed for the analysis of jet fuels. The method employs a short-column (3 m by 0.25 mm inside diameter by 1.0 μm thick film) DB-5 capillary for sample introduction into the mass spectrometer. The calculational aspects of the technique are based on the current ASTM Test Method for Hydrocarbon Types in Low Olefinic Gas-oline by Mass Spectrometry (D 2789-86) inverse calibration matrices. An evaluation of component discrimination with GC introduction was performed as a function of injection port temperatures and injection methods. The analytical figures of merit such as sensitivity and limit of detection were determined. Comparisons between the GC/MS/HTA and ASTM D 2789-86 results of several test fuels were made. Additionally, several synthetically prepared fuels were analyzed by the GC/MS/HTA method in order to evaluate the accuracy of the method.
Tandem Mass Spectrometry for the Determination of Trace Steranes in Crude and Shale Oils
Authors: Johnson JV , Yost RA , Wong CM
Published: December 2008

Triple quadrupole tandem mass spectrometry (MS/MS) has been used to characterize the MS/MS behavior of five sterane standards and then to determine the sterane distribution in two shale oils and a crude oil without prior sample cleanup. Comparisons were made between electron ionization (EI) MS/MS and methane positive-chemical ionization (PCI) MS/MS of the sterane standards and the three oils. The EI-MS/MS of the molecular ions (M+) of the steranes was determined to be more sensitive and selective than PCI-MS/MS of the corresponding (M - H)+ ions. With solids probe/EI-MS/MS parent scan of m/z 217 (the most characteristic daughter ion for steranes), it was possible to obtain the sterane distribution in the three oils. However, due to chemical interferences, only the most abundant steranes could be confirmed by the complete EI-MS/MS daughter spectra of the detected molecular ions. In addition, severe contamination of the instrument resulted due to introduction of the oils into the vacuum system on the solids probe. Some sample cleanup would be beneficial in order to enhance the ability to detect low-level steranes and to prevent instrument contamination.
Gas Chromatography/Mass Spectrometry Analysis of n-Alkylbenzothiophenes Identified in Arabian Heavy Asphaltenes, Pyrolysis Oil
Authors: Gallegos EJ
Published: December 2008

Present concepts hold that the genesis of organic sulfur compounds is due mainly to secondary processes. The secondary process is a chemical reaction of oil with sulfur or sulfur species to give nonthiophenic sulfides and thiols first, then benzothiophenes, and ultimately stable dibenzothiophenes. This work describes the pyrolysis gas chromatography/mass spectrometry (GC/MS) identification of a homologous series of n-alkylbenzothiophenes extending from C10 to C30 in Arabian Heavy asphaltenes. Within each homolog there are at least 22 isomers. The mass spectra of these isomers typically show relatively intense molecular ions with base peaks at m/z 147, 161, or 175.

The striking similarity of the fragmentation profiles of the homologous benzothiophenes and homologous n-alkylbenzenes also present in the sample strongly suggests that the benzothiophenes are generated directly from the reaction of the alkylbenzenes with sulfur species. Reflux experiments with known alkylbenzenes and elemental sulfur produced an abundance of thiophene derivatives including benzothiophenes.
An Expert Program for the Interpretation of Gas Chromatography/Mass Spectrometry Data on Fossil Fuel Distillates
Authors: Aczel T , Colgrove SG , Le L
Published: December 2008

An expert system has been developed for the interpretation of the gas chromatography/mass spectrometry (GC/MS) spectra of fossil fuel distillates. The approach extends the scope of commercially available data systems by using interpretation rules generally carried out by a skilled professional expert. The rules and procedures incorporated in the program deconvolute unresolved peaks, set acceptability limits for the identifications provided by commercial data systems, and identify components that the commercial data systems fail to identify, or identify incorrectly, at least as to compound class and carbon number.

Need for such an approach stems from the inability of commercial data systems to deal adequately with complex hydrocarbon mixtures. The spectral matching algorithms used by these systems do not consider spectra/structure correlations and fail when GC/MS peaks are unresolved or pure compound spectra are not available for comparison or both. These conditions occur in the majority of cases with boiling range above 149°C (300°F). The expert program discussed in the paper obviates these difficulties. It results in 90 to 95% correct identifications, 99% plus on a concentration basis, and it saves 20 to 30 h of skilled time per sample.
Background and Development of ASTM D 4378: Practice for In-Service Monitoring of Mineral Turbine Oils for Steam and Gas Turbines
Authors: Roberton RS
Published: December 2008

Several years ago a study group was set up at ASTM (American Society for Testing and Materials) under Subcommittee C (Turbine Oils) of Committee D-2 on Petroleum Products and Lubricants to develop a standard for in-service monitoring of steam and gas turbine oils. The study group included well qualified and experienced representatives from turbine equipment builders, oil producers, the power generation industry, and consultants among its members. The objective was achieved and an ASTM standard D 4378, entitled “Practice for In-Service Monitoring of Mineral Turbine Oils for Steam and Gas Turbines” was issued as a single standard in 1984 and is now included in the Annual Book of ASTM Standards. In developing the standard, it was recognized that turbine oils are unique lubricants requiring the highest degree of oxidation stability and resistance to sludge formation and are expected to give years of service. Also, the high cost of oil changes and unplanned shutdowns had to be balanced against the cost of laboratory manpower and equipment for analytical testing.

This paper covers the results of an initial study of monitoring practices within the power generation industry and discusses in some detail why some methods in use for many years are of doubtful significance and should be eliminated. It also describes the development of sampling and testing schedules. To follow the oxidative degeneration of the oil, the well-established TAN (Total Acid Number) test is retained and used in conjunction with the Rotary Bomb Oxidation Test, (RBOT) (D 2272) to provide a much more reliable indication of remaining service life. Other properties of the oil which must be retained in service are discussed, and major significance has also been given to the interpretation of test data and appropriate action steps.

The technical merit of D 4378 and its acceptance by the international community is confirmed by the fact that it has been used by a joint working group of ISO (International Standards Organization) and IEC (International Electrotechnical Commission) as a basis for an international maintenance and use guide.
A Turbine Lube Oil System Monitoring Program
Authors: Bonett D
Published: December 2008

Con Edison has 32 steam turbines and 100 gas turbines in many locations in New York City and Westchester County. A monitoring program is administered from a central organization, but tested and tracked on site. The test results, when trended graphically, are used to predict system problems and to plan corrective action with the intent to eliminate catastrophic unit failures. The monitoring program as outlined can be used as a model to plan a specific program.
A Supplier's Approach to Turbine Oil Monitoring
Authors: Trabert GR , Schreuders GJ
Published: December 2008

To ensure the successful operation of a turbine circulating oil system, the turbine manufacturer, the turbine operator, and the lubricant supplier must cooperate by furnishing their technical expertise.

Examples of turbine oil problems show that effective sampling procedures and monitoring of turbine oils is required to assure a long service life. ASTM Practice for In-Service Monitoring of Mineral Turbine Oils for Steam and Gas Turbines (D 4378) is an excellent guide to accomplish this.
The Reliable Control of Oil Quality in Japanese Turbine Units
Authors: Ohgake R , Sunami M , Yoshida T , Watanabe H
Published: December 2008

The reliable operation of Japanese steam, gas, and water power turbines using a newly developed trouble-resistant oil in association with a successful maintenance service system is discussed.

A classic steam turbine oil formula containing a phenolic oxidation inhibitor and a succinic acid-type rust inhibitor made from low-aromatic base stock has been used for trouble-free maintenance. In Japan, the oil supplier and the user jointly administer quality control programs for turbine oils. The accumulated data of the oil supplier are utilized for estimating the optimum oil makeup for individual turbines. Since the installation of several computerized systems responsible for maintaining the quality of steam turbine oil in 165 power stations, the remaining life of the oil has been maintained over the warning limit by estimating the optimum oil's makeup.

Remote control systems have been employed at many small hydroelectric power plants in Japan to save manpower. Such modernization has brought about an additional lubrication problem—severe valve sticking. More than 100 water turbine generators have suffered from this problem since around 1965. Maintenance-free type oil was required for these units. A new-type turbine oil for which a sludge dispersant is employed has solved this valve-sticking problem. The evaluation method and in-service performance are provided.

The largest combined-cycle power station in the world (output 2000 MW) was recently installed at Futsu Power Station of the Tokyo Electric Co. (in 1985). The lubrication of 14 heavy duty gas turbines (GE9001E, 113 MW) is performed by a new high-temperature gas turbine oil. This oil has done well, providing more than 8000 trouble-free hours of lubrication. The oil quality monitor and control systems are discussed.
Monitoring Practices for Phosphate Ester Fluids for Turbine Lubrication and Control
Authors: Anzenberger JF
Published: December 2008

In-service monitoring of the customer's phosphate ester turbine oils has been practiced for over 15 years. This service originated with users of electrohydraulic control (EHC) fluids and gradually expanded to include specialty-type synthetic triaryl phosphate ester lubricants for large and medium-sized gas turbines and turbine-compressor operations. In-service monitoring is intended to assist the user in caring for the fluid to obtain maximum service life. Users who avail themselves of this service have their used fluids examined for various properties, which could include as many as seven measurements: viscosity, acid number, specific gravity, water content, mineral oil content, fire properties, and stability. Corrective actions are suggested if a fluid exceeds certain property measurements.
Experiences with an Analytical Monitoring Program Designed for Commercial Flight Tests of Advanced Mil-L-23699 Turbine Fluids
Authors: Pachuta DG , Thich JA , Knipple RW , Stephanic DA
Published: December 2008

Aviation turbine engine manufacturers possess different philosophies concerning the qualification of new turbine fluids for commercial aircraft. Most require a flight test employing a monitoring program that was designed to measure only basic fluid parameters such as viscosity, total acid number, etc. Warning limits for changes in these parameters were generally established from the performance characteristics of earlier generations of turbine fluids and older engine designs which imposed less operational stress upon the fluid charge. Recent flight test experience with a third generation Mil-L-23699 fluid suggests that revisions to currently recognized programs and parameter limits should be made in order to properly reflect modern engine hardware features, airline operating practices, and advanced additive behavior. It is recommended that analytical techniques such as plasma-based atomic emission spectrometry, size exclusion chromatography, gas chromatography, and thermal analysis be integrated into existing flight test programs. A “two-stage” monitoring scheme consisting of standard physical-chemical tests and these analytical techniques provided essential data about the fluid's response to thermooxidative and operational stress. Compositional information needed to detect and identify contaminants such as hydraulic and other foreign fluids was also obtained. Specific examples are cited about the diagnostic abilities of this analytically oriented monitoring program.
Weight Function Theory for Three-Dimensional Elastic Crack Analysis
Authors: Rice JR
Published: December 2008

Recent developments in elastic crack analysis are discussed based on extensions and applications of weight function theory in the three-dimensional regime. It is shown that the weight function, which gives the stress intensity factor distribution along the crack front for arbitrary distributions of applied force, has a complementary interpretation: It characterizes the variation in displacement field throughout the body associated, to first order, with a variation in crack-front position. These properties, together with the fact that weight functions have now been determined for certain three-dimensional crack geometries, have allowed some new types of investigation. They include study of the three-dimensional elastic interactions between cracks and nearby or emergent dislocation loops, as are important in some approaches to understanding brittle versus ductile response of crystals, and also the interactions between cracks and inclusions which are of interest for transformation toughening. The new developments further allow determination of stress-intensity factors and crack-face displacements for cracks whose fronts are slightly perturbed from some reference geometry (for example, from a straight or circular shape), and those solutions allow study of crack trapping in growth through a medium of locally nonuniform fracture toughness. Finally, the configurational stability of cracking processes can be addressed: For example, when will an initially circular crack, under axisymmetric loading, remain circular during growth?
Microchemistry and Mechanics Issues in Stress Corrosion Cracking
Authors: Jones RH , Danielson MJ , Baer DR
Published: December 2008

Environmentally induced subcritical crack growth occurs in most metallic ma terials given the appropriate material, environment, and stress conditions. Much is known about the conditions which cause stress corrosion cracking (SCC) in metallic materials, but much less is known about the processes which control environment-induced crack initiation and propagation. There is presently no description of the flaw length, flaw shape, and local chemistry conditions that coincide with the transition from a localized corrosion phenomenon and the initiation of a crack. Although there have been considerable attempts to describe the rate-limiting steps in crack propagation, a number of issues are unresolved, including specifics about the crack-tip conditions, crack length effects, processes controlling the Stage I SCC region, and details about the crack advance processes in both transgranular stress corrosion cracking (TGSCC) and intergranular stress corrosion cracking (IGSCC). A summary of these unresolved issues and some analysis of their effect on SCC is given in this paper.
The New High-Toughness Ceramics
Authors: Evans AG
Published: December 2008

The principal microstructural sources of toughening are reviewed, with emphasis on comparisons between theory and experiment. Process zone mechanisms, such as transformation and microcracking, as well as bridging mechanisms induced by either ductile networks or fiber/whiskers are afforded primary consideration. Microstructural variables that allow toughness optimization are established.
An Efficient Finite-Element Evaluation of Explicit Weight Functions for Mixed-Mode Cracks in an Orthotropic Material
Authors: Sha GT , Yang C-T , Ong JS
Published: December 2008

An efficient finite-element methodology, which uses the energy perturbation concept for evaluating the decoupled weight functions (hI(II)) of a mixed-mode crack in an orthotropic material, is presented. The methodology is achieved by applying a single colinear virtual crack extension technique to a symmetric mesh in the crack-tip neighborhood with the crack lying on one of the elastic symmetry planes. The use of symmetric mesh permits analytical separation of all field parameters of stresses, strains, displacements, tractions, and strain energy release rates into Mode I and Mode II components within the symmetric mesh zone. Once the decoupled explicit weight functions are predetermined explicitly for a given crack geometry, the decoupled stress-intensity factors, KI(II), under any loading conditions can be evaluated efficiently and accurately by a sum of worklike products between the applied tractions and the explicit weight functions at their application locations. Comparing the decoupled stress-intensity factors (KI(II)) obtained from the predetermined explicit weight functions for the orthotropic crack with those of well-established literature data shows good agreement with identical crack geometry, loading, and orthotropic properties but with different approaches.
Automated Generation of Influence Functions for Planar Crack Problems
Authors: Sire RA , Harris DO , Eason ED
Published: December 2008

A numerical procedure for the generation of influence functions for Mode I planar problems is described. The resulting influence functions are in a form for convenient evaluation of stress-intensity factors for complex stress distributions. Crack surface displacements are obtained by a least-squares solution of the Williams eigenfunction expansion for displacements in a cracked body. Discrete values of the influence function, evaluated using the crack surface displacements, are curve fit using an assumed functional form. The assumed functional form includes appropriate limit-behavior terms for very deep and very shallow cracks. Continuous representation of the influence function provides a convenient means for evaluating stress-intensity factors for arbitrary stress distributions by numerical integration. The procedure is demonstrated for an edge-cracked strip and a radially cracked disk. Comparisons with available published results demonstrate the accuracy of the procedure.
Effect of Loading Rate and Thermal Aging on the Fracture Toughness of Stainless-Steel Alloys
Authors: Mills WJ
Published: December 2008

The effect of loading rate on the fracture toughness of Types 304 and 316 stainless-steel plate and Type 308 weld before and after thermal aging was characterized using both fracture mechanics and Charpy specimens. Aging at 566°C for 10 000 h reduced static Jc initiation toughness values for both wrought and weld metals by 10 to 20%, and tearing moduli were reduced by 20 to 30%. Under semi-dynamic and dynamic loading conditions, the fracture resistance was not decreased below the static response for either unaged or aged materials. The present results also demonstrated that the large degradation in Charpy V-notch impact energy after aging was not representative of the impact resistance for stainless-steel components containing cracks or crack-life defects. Fractographic examinations revealed that the large loss in Charpy energy was associated with aging-induced microstructural changes that substantially decreased the energy required to initiate a crack from a blunt notch. At very slow strain rates, creep crack growth was found to cause a significant degradation in fracture toughness.
Fatigue Crack Growth Under Combined Mode I and Mode II Loading
Authors: Stanzl ES , Czegley M , Mayer HR , Tschegg EK
Published: December 2008

The influence of static Mode I and static Mode II loading on Mode I fatigue crack growth has been studied with 12 weight % chromium steel.

Static Mode I was superimposed as a tensile load on fatigue-loading with mean stress equal to zero, thus resulting in R-values of - 1, - 0.33, 0, +0.25, and +0.5. For these values, fatigue-crack growth curves were determined in the threshold regime with crack growth rates typically between 3 × 10-13 and 5 × 10-9 m/cycle.

In addition, a constant static Mode II load was superimposed on the same above-mentioned Mode I load. The resulting crack growth rates were found to vary systematically with crack length and load ratio. For R-ratios ⩽ 0 enhanced fatigue crack growth rates were observed at crack lengths up to a defined value. After a certain crack length was attained, slightly reduced crack growth rates were detected. For high R-ratios, long as well as short fatigue cracks grew slower than under pure Mode I fatigue loading. The results are discussed in light of the crack closure phenomenon and the fracture morphology, which was studied in a scanning electron microscope (SEM).

In the Appendix, a basic procedure for determining stress-intensity values for high-frequency (21 kHz) fatigue loading is given in comparison with conventional loading.
On the Influence of Crack Plane Orientation in Fatigue Crack Propagation and Catastrophic Failure
Authors: Banks-Sills L , Schur D
Published: December 2008

During fatigue crack propagation in sufficiently thin metallic sheets, shear lips develop which spread throughout the material thickness. This leads to a situation where, in addition to a Mode I component of deformation, there is also a Mode III component. Finite-element calculations are carried out on several geometries in an attempt to assess the effect of this additional deformation upon catastrophic failure and fatigue crack propagation. for these particular geometries, it is shown that the slant crack is less dangerous than the flat crack with regard to catastrophic failure and, when propagating in fatigue, may grow faster or slower than the flat crack.
A Finite-Element Investigation of Viscoplastic-Induced Closure of Short Cracks at High Temperatures
Authors: Palazotto A , Bednarz E
Published: December 2008

The authors have developed a finite-element program with constant-strain capabilities that can handle cyclic loading. The constitutive relation is considered to be elastic-viscoplastic incorporating the Bodner-Partom flow rule. Incalloy 718 is the alloy considered at a temperature of 670°C. The computer algorithms are discussed for consideration of crack closure and extension.

The program is applied to a single-edge-cracked specimen with an initial crack length of 25 μm acting under a load distribution of 90% of the yield stress for the material considered. A plane-stress finite element is used to evaluate the effect of an R-value equal to 0.1, considering frequencies of 0.01 and 1.0 Hz. The crack is allowed to grow to a final length of 46 μm. The plastic zone in front of the crack tip is approximately equal to the initial crack length, yielding conditions associated with short cracks.

The results indicate the effect viscoplasticity plays when considering and comparing two separate frequencies. A plastic wake, due to crack closure, develops behind the propagating crack and increases for the lower frequency. In order to realistically predict plasticity-induced closure, one must mathematically allow the crack to grow. Stress and strain fields in front of the crack show a noticeable change with time due to the viscoplastic effect.
Influence of Cathodic Charging on the Tensile and Fracture Properties of Three High-Strength Steels
Authors: Tremblay V , Nguyen-Duy P , Dickson JI
Published: December 2008

The influence of cathodic charging in sulfuric acid solution on mechanical properties of AISI 4340, AISI 300M, and AMS 6340 steels was studied for different tempering temperatures. Cathodic charging decreased the tensile elongation, the reduction in area, and the ultimate tensile stress as a result of hydrogen-induced surface cracks having brittle features, which then transformed into cracks propagating by microvoid nucleation and coalescence along planes of maximum shear stress.

The curves of the J-integral as a function of the crack advance Δa presented a change in slope at a small Δa value. For the lower tempering temperatures, this Δa value was relatively large and similar to that required to obtain a single crack propagating across the thickness. Cathodic charging decreased JIc as a result of bands of brittle cracking near each lateral surface and of facilitated initiation of cracking, in an alternating fashion along planes of maximum shear stress.
Strength of Stress Singularity and Stress-Intensity Factors for a Transverse Crack in Finite Symmetric Cross-Ply Laminates Under Tension
Authors: Bai J-M , Loo T-T
Published: December 2008

A theoretical investigation into the mechanics of the failure phenomenon of a composite laminate is presented. The study is specialized to the problem of a finite [0/90]s symmetric cross-ply composite laminate with a transverse through-crack under uniaxial tension. The stress field of such laminates is analyzed with particular emphasis on the stress singularity of the crack and the corresponding stress-intensity factors. The Lekhnitskii's method of complex stress functions for anisotropic bodies [1] is employed in the analysis of the strength of crack singularity. The crack problem is solved by analytic method, and the solution is expressed in the form of the sum of two infinite series of Fourier-hyperbolic functions supplemented by a singular term with predetermined order. Through numerical computation, the effects of the material constants and geometric parameters on the stress-intensity factors are obtained. They seem to furnish a reasonable explanation to the observed failure phenomenon.
Fracture Behavior of Compacted Fine-Grained Soils
Authors: Fang H-Y , Mikroudis GK , Pamukcu S
Published: December 2008

Existing cracks, when triggered to advance, often contribute to the progressive failure mechanism and erosion of slopes, embankments, excavations, river banks, and other earthen structures of compacted fine-grained soils. To assess the effect of existing cracks on these earth structures it is necessary to quantitatively measure the magnitude of load necessary to advance the crack to failure. This load has been defined as the fracture load of soils in previous investigations.

This study reports the results of an experimental procedure used to measure the fracture load and its variation with precrack length and also evaluate the load deflection relations for compacted clays and marine clays. A simple procedure, based on concepts of linear elastic fracture mechanics (LEFM) theory, was utilized. Soil specimens were prepared and tests were conducted according to ASTM Method E 399. Fracture load and fracture toughness were evaluated. Results indicate that reasonable estimations of fracture load in clay soils could be made using the fundamentals of LEFM theory, which constitutes the basis of the fracture toughness analysis.
Oxidation and Deuterium Uptake of Zr-2.5Nb Pressure Tubes in CANDU-PHW Reactors
Authors: Urbanic VF , Warr BD , Manolescu A , Chow CK , Shanahan MW
Published: December 2008

Oxidation and deuterium uptake in Zr-2.5Nb pressure tubes are being monitored by destructive examination of tubes removed from commercial Canadian Deuterium Uranium Pressurized Heavy-Water (CANDU-PHW) stations and by analyses of microsamples, obtained in-situ, from the inside surface of tubes in the reactor. Unlike Zircaloy-2, there is no evidence for any acceleration in the oxidation rate for exposures up to about 4500 effective full power days. Changes towards a more equilibrium microstructure during irradiation may be partly responsible for maintaining the low oxidation rate, since thermal aging treatments, producing similar microstructural changes in initially cold worked tubes, were found to improve out-reactor corrosion resistance in 589 K water.

With one exception, the deuterium uptake in Zr-2.5Nb tubes has been remarkably low and no greater than 3-mg/kg deuterium per year (0.39 mg/dm2 hydrogen per year). The exception is the most recent surveillance tube removed from Pickering (NGS) Unit 3, which had a deuterium content near the outlet end about five times higher than that seen in the previous tube examined. Current investigations suggest that most of the uptake in that tube may have come from the gas annulus surrounding the tube where deuterium exists as an impurity, and oxidation has been insufficient to maintain a protective oxide film.

Results from weight gain measurements, chemical analyses, metallography, scanning electron microscopy, and transmission electron microscopy of irradiated pressure tubes and of small coupons exposed out reactor are presented and discussed with respect to the observed corrosion and hydriding behavior of CANDU-PHW pressure tubes.
Influence of the Manufacturing Process on the Corrosion Resistance of Zircaloy-4 Cladding
Authors: Schemel JJ , Charquet D , Wadier J-F
Published: December 2008

A study of a wide range of thermomechanical processing parameters for the manufacture of fuel clad tubing revealed that the corrosion resistance in 673 and 698 K steam varied little within the variations expected to occur in current commercial processing. Long exposure to 673 K steam was used as the test most likely to relate to in-reactor performance with the time to departure from the usual multiple rate transition behavior believed to be the significant measure of performance. The parametric study commenced with the beta heat treatment before extrusion where time at temperature and cooling rate were varied. No changes were made in the extrusion process, but several combinations of anneals during the cold reduction sequences were applied to produce a set of 23 variants. Corrosion tests on the extruded and tube reduced tube hollows without an anneal showed an adverse effect on corrosion resistance of the very high quench rates on the outer surface of the billet. Data from the test series made it possible to estimate that a cooling rate of about 20 to 40 K/s produced a minimum in the weight gain in a 673 K corrosion test. The adverse effect of the high cooling rates illustrated on the outer surface of unannealed tube reduced extrusion (TREX) specimens is eliminated by the subsequent heat treatments and is not seen on either annealed TREX or the tubing made from it. The annealing parameter provided a good measure of corrosion behavior only for identical final tube heat treatments. The difference between unannealed, stress relieved, and recrystallized tubing is not predicted by application of this annealing parameter alone. Increasing the annealing parameter from 2.3 × 10-18to29 × 10-18h improved the corrosion resistance of unannealed cold-worked tubes but did not affect the stress relieved or recrystallized tube specimens. In the same manner, unannealed cold-worked tubes display an effect of quenching conditions when stress relieved tubes did not. A series of tests with various amounts of metal removed from the outer surface of the heat treated tubes showed that the corrosion resistance was largely constant through the tube wall in the 673 K steam test, again showing that the effect of cooling rate at the billet stage was removed by subsequent heat treatment. The test series confirmed the observation in earlier work that a cumulative annealing parameter greater than 10-18 h is sufficient to provide uniformly good corrosion resistance in Zircaloy-4.
Automatic System for Measuring the Zirconium Liner and Zircaloy-2 Thickness of Zirconium Liner Tubes
Authors: Honji M , Sakamoto T , Morimoto Y , Hyodo S
Published: December 2008

An automatic system to measure the zirconium liner thickness and Zircaloy-2 thickness of Zircaloy tubes with a zirconium liner for nuclear reactors has been developed. This system uses an electromagnetic probe connected to a data processing unit for measuring the liner thickness, an ultrasonic inspection system for measuring the wall-thickness, and a computer for calculating the Zircaloy-2 thickness from the liner thickness and wall-thickness. Fully automatic measurements on zirconium liner thickness and Zircaloy-2 thickness are performed with high accuracy to an order of 2μm. This newly developed system is very useful in assuring the liner layer and Zircaloy-2 thickness in the production of high-quality cladding tubes.
Diffusion of 3D Transition Elements in α-Zr and Zirconium Alloys
Authors: Hood GM , Schultz RJ
Published: December 2008

Measurements of tracer diffusion coefficients D of Fe-59, Ni-63 and Cr-51, in zirconium single crystals and of Fe-59 in some zirconium alloys have been made. The single crystal measurements were made in directions both parallel Dǁ and perpendicular D⊥ to the c axis of the specimens; results for nickel were obtained at 1025, 883, and 674 K and for iron at 674 K. The low temperature diffusion profiles are generally complex and indicate the probable operation of more than one diffusion process. The diffusion behavior of nickel in zirconium seems to parallel that of iron, for which more data are available and, probably, that of cobalt; at high temperatures, the effective activation energy for diffusion hD is approximately 0.6 eV, while at lower temperatures, a value closer to 2.0 eV seems more appropriate. The diffusion profiles indicate that Dǁ D⊥ at all temperatures, though there is a tendency for the anisotropy to diminish as the temperature decreases. The high-temperature results, associated with intrinsic behavior, conform to previously developed, diffusion parameter/atomsize correlations. The lower temperature data are probably symptomatic of complexing and precipitation effects. Chromium diffusion measurements have been made at 887, 977, and 1114 K. The diffusion profiles are generally well-behaved, and D(T) obeys the customary Arrhenius law D = D° exp (-hD/kT) with values of 2.4 × 10-6 2and 9.5 × 10-6 m2s for D°(ǁ) and D°(⊥), respectively, and 1.39 and 1.61 eV for the corresponding hDǁand h°⊥ parameters. The chromium D values are in general agreement with some earlier data; Dǁ is from 2.6 to 5.2 D⊥, and the ratio increases with decreasing temperature.

In addition to the above, measurements of iron diffusion in Zircaloy-2 and Zr-2.5wt% Nb have been made at 893 and 1122 K. The diffusion profiles are reasonably well behaved; the associated Ds are from 20 to 100 times lower than corresponding D(Fe) values for nominally pure single crystal α-Zr; the alloy D(Fe) results are very similar to previous, corresponding D(Ni) data for these alloys. Isolated diffusion measurements have also been made on a Zr-1.08 at% Sn alloy, at 1121 K, and on single crystals of Zr-0.1 at% Fe, at 1054 K. The values of Dǁ|, D⊥, and the associated ratio, Dǁ/D⊥, for the Zr(Fe) alloy are all somewhat lower than the corresponding data for iron diffusion in pure α-Zr. In addition, the Zr(Fe) alloy showed remarkable compositional variations; some comment on this behavior is made.
Simulated Fuel Expansion Testing of Zircaloy Tubing
Authors: Foster JP , Leasure RA
Published: December 2008

Expanding mandrel (Simulated Fuel Expansion or Simfex) pellet-cladding interaction (PCI) simulation tests were performed on unirradiated Zircaloy-2, Zircaloy-4, zirconium-lined Zircaloy-2, Zircaloy-3A alloy-lined Zircaloy-2, and graphite-lined Zircaloy-4 tubing with high-purity argon and iodine. SIMFEX tests were also performed on irradiated Zircaloy-4 cladding in iodine. Sensitivity tests were performed on unirradiated unlined Zircaloy-4 tubing in order to establish SIMFEX test conditions that simulate PCI. Test variables included test temperature, core compression rate (or sample strain rate) and iodine partial pressure. SIMFEX test parameters that simulate PCI cover a wide range of test conditions. At a given temperature, these test conditions depend on core compression rate and iodine partial pressure. Iodine SIMFEX tests on unlined unirradiated and irradiated Zircaloy-4 showed that the PCI simulation test conditions produce fractures similar to fuel rod ramp tests. The zirconium-lined Zircaloy-2, Zircaloy-3A alloy-lined Zircaloy-2 and graphite-lined Zircaloy-4 tubing exhibited excellent resistance to simulated PCI failure. Similar diameter fracture strains were exhibited by the zirconium-lined Zircaloy-2 and Zircaloy-3A alloy-lined Zircaloy-2 while significantly higher diameter fracture strains were measured on the graphite-lined Zircaloy-4 tubing. The results of these tests will be used to discuss iodine stress corrosion cracking liner performance mechanisms.
The Push-in Pressuremeter: 5 Years Offshore Experience
Authors: Fyffe S , Reid WM , Summers JB
Published: December 2008

The importance of in-situ testing of soils has been recognised for some time. To extend the equipment available for in-situ testing in an offshore environment, the British Government financed the development of a wireline operated push-in pressuremeter and since 1980 the Stressprobe has been used extensively offshore. This paper updates the record of tests carried out with the Stressprobe equipment since 1982 and describes the software used for test evaluation. Examples of test data are given and alternative forms of analysis are compared.
Self-Boring Pressuremeter in Po River Sand
Authors: Bruzzi D , Ghionna V , Jamiolkowski M , Lancellotta R , Manfredini G
Published: December 2008

The results of a series of self-boring pressuremeter tests (SBPT) carried out in the quaternary Po river sand are presented. Assessment of total horizontal in situ stress, shear modulus and shear strength, of the tested sand is discussed. Comments on the use of the above mentioned parameters in practice are advanced.
The Calibration and Use of a High Capacity Pressuremeter to Determine Rock Stiffness
Authors: Bacciarelli RE
Published: December 2008

Rubber membrane type pressuremeters are in common use worldwide for the determination of the in situ deformation characteristics of rock. Standard correction values and data reduction methods quoted by the equipment manufacturer are conventionally used to process pressuremeter test data. A basic assumption of the data reduction procedure is that the rubber membrane behaves elastically. However problems experienced with the non-elastic behaviour of a thick rubber membrane during an investigation in the UK resulted in a complete reassessment of calibration techniques and data reduction procedures. Revised on site calibration and test procedures are proposed, together with a simple method for data reduction and modulus determination. It is apparent that frequent and stringent calibration of the pressuremeter test equipment is essential to avoid errors in both data reduction and modulus determination.
Effective Stress Analysis of Soil Response in a Pressuremeter Test
Authors: Juran I , Beech JF
Published: December 2008

A simple rheological model for analyzing pressuremeter test results, which includes pore water pressure measurements, is presented. The soil is assumed to be an elasto-plastic material with a non-associated flow rule. The governing equation of the yield surface and the plastic flow potential are based on parameters which can be obtained from standard tests, such as triaxial compression tests. A parameter is introduced which accounts for the contracting and/or dilating behavior of the soils during expansion. The model is applied to pressuremeter test results obtained in a contracting, lightly overconsolidated clayey silt. The shear modulus, effective strength characteristics, and a parameter characterizing the contracting behavior of the soil are determined. The results of a numerical analysis, incorporating the proposed rheological model, simulating the pressuremeter tests are compared with the field test results.
Interpretation of Pressuremeter Tests Using Laboratory Simulated Tests
Authors: Gangopadhyay CR , Nasr AN
Published: December 2008

At least five different methods are available to interpret the results of field pressuremeter tests for saturated clays, each of which has been reported to yield different values of soil parameters when applied to the same pressuremeter test. In the present investigation, a laboratory pressuremeter model was developed, and simulated pressuremeter tests were run on a sedimented Kaolinite consolidated to different values of the maximum vertical pressure, gsv, and with overconsolidation ratios (OCR) ranging from 1 to 8. Analyses of the model pressuremeter tests indicate that the differences in normalized shear strength, Su/gsv, using the five interpretation methods are large with the difference increasing with increasing overconsolidation ratio. The method by Prevost gave the best fit with the Su/gsv vs OCR relationship determined by the average of KoU Triaxial compression and extension strengths.
Expansion of a Cylindrical Cavity in a Very Deformable Medium: A Theoretical Study
Authors: Soulié M , Ladanyi B , Degenne P
Published: December 2008

Most classical solutions for stress and strain distribution around an expanding cavity that have up to now been used for the interpretation of pressuremeter tests in soils, have been based essentially on a small strain assumption. This paper presents a finite element method solution of the problem of an expanding cylindrical cavity, which is based on a new incremental formulation, considered to lead to a more correct representation of large strain problems than some earlier ones. In addition, a new large-strain analytical solution is developed in the paper, which is shown to be able to determine the limit cylindrical expansion pressure, even for very deformable materials, which are outside the scope of classical solutions.
Analysis of the Unloading of a Pressuremeter in Sand
Authors: Houlsby GT , Clarke BG , Wroth CP
Published: December 2008

The self-boring pressuremeter offers a particular advantage in that it can be installed in the ground with minimal disturbance. The loading stage of a pressuremeter test in sand has been analysed previously in terms of the shear modulus, angle of friction, angle of dilation and the initial horizontal stress and pore pressure. A new analysis is presented of the unloading stage of the pressuremeter test; this can provide a separate check on the parameters measured during the loading stage. An optimisation routine is used to fit the properties to the results of a series of tests at a site in Wales. Various important effects are discussed, including the effect of stress level on the shear modulus and the relevant value of the angle of friction to be used for the unloading stage.
Undrained Strength and Deformation Parameters from Pressuremeter Test Results
Authors: Anderson WF , Pyrah IC
Published: December 2008

Pressuremeter tests in cohesive soils are generally analysed to give undrained strength parameters. Differences in pressuremeter test techniques have been shown to affect test results and derived parameters, and it has been established that these variations are due to the combined time-dependent effects of local consolidation and deviatoric creep. Various sizes of pressuremeter are used offshore. The influence of consolidation and creep on the results of tests carried out using pressuremeters with different initial diameters has been examined using a numerical analysis. This has shown that the initial size of the expanding cavity can have a significant effect on the test results. The numerical simulations have also shown that the influence of test technique cannot simply be expressed as the ‘time to failure’; the way in which the test is performed also affects the results.