bluuebunny/crossref_metadata_2025 huggingface dataset:
Stability of Subtrochanteric Femoral Fractures Fixed with Interlocking Intramedullary Rods
Authors: McKellop H , Ebramzadeh E , Fortune J , Sarmiento A
Published: December 2008

A variety of designs of interlocking intramedullary rods has been developed in recent years for fixation of otherwise unstable femoral fractures. In this study, plastic model femurs with either stable transverse subtrochanteric osteotomies or unstable subtrochanteric defects were used to compare the rotational stiffness provided by different types of intramedullary rods. Simultaneous axial, bending, and torsional loading was applied to examine the effect of rod-bone and fracture surface interaction on rotational stiffness. For the stable transverse fracture, increasing the axial load from 150 to 1000 N increased the rotational stiffness as much as 5.7 times (Zickel nail). Thus, a large component of the resistance to rotation was due to interaction of the fracture surfaces. In contrast, with the unstable segmental defect, rotational stiffness was primarily dependent on the inherent torsional stiffness of the implant. For example, the fracture fixed with a double-interlocked tubular titanium rod was about seven times stiffer in rotation than fractures fixed with slotted-cloverleaf intramedullary rods. Close comparison of these experimentally measured characteristics with actual clinical performance will be necessary to identify the optimum design features for interlocking intramedullary devices.
Defect Particles in an Irradiated RPV Steel Studied by a Systematic Variation of Irradiation and Annealing Conditions: Preliminary Results by Small Angle Neutron Scattering
Authors: Solt G , Frisius F , Waeber WB
Published: December 2008

Defect particles with typical mean radii of 7 to 9 Å were detected by SANS in neutron-irradiated (E > 1 MeV) steel specimens cut out of the same block and subjected to four various fluences in the range (0.5 to 5.0) × 1019 n/cm2. In addition to the as-irradiated condition, the effect of a heat treatment after irradiation and, in another series of experiments, the consequences of an anneal in between the two halves of the irradiation period were studied.

The forged RPV material contains 0.173 wt% Cu and 1.47 wt% Mn; the irradiations at the given fluences were performed at 290°C in a research reactor. The SANS results show that: 1. In the as-irradiated condition themean particle radius is ˜9 Å and the size distribution functions are reasonably sharp (ΔR/¯R = 0.25). For the smaller doses the mean radius is somewhat smaller (6 to 8 Å). The average copper content of the particles is c = 50 to 70 at% calculated on the base of a copper-vacancy agglomerate model, and it varies but slightly with the fluence. For the volume fraction we obtain f= 0.15 to 0.18% except for the lowest fluence. 2. Post irradiation annealing (420°C/24 h) decreases the particle volume fraction as expected, and it also broadens the size distribution. The scattering contrasts show the significantly higher copper content in the damage particles (c = 85 to 90 at%) than in the as-irradiated material. 3. The irradiated-annealed (450°C/168 h)-reirradiated samples show a qualitatively different scattering pattern. One-peaked size distributions, even if very broad (ΔR/¯R ˜ 0.45), give at best a moderately good fit only to the small fluence data, and two characteristic particle sizes could be determined for the higher fluence samples (¯R1 = 7 to 9 Å and ¯R2 = 20 to 30 Å)with f= 0,07 to 0.14%.
Fiber Composite Structural Durability and Damage Tolerance: Simplified Predictive Methods
Authors: Chamis CC , Ginty CA
Published: December 2008

Simplified predictive methods and models (“theory”) to evaluate fiber/polymermatrix composite material for determining structural durability and damage tolerance are described. This “theory” includes equations for: (1) fatigue and fracture of composites without and with defects; (2) impact resistance and residual strength after impact; (3) thermal fatigue; and (4) combined stress fatigue. Several examples are included to illustrate applications of the “theory” and to identify significant parameters and sensitivities. Comparisons with limited experimental data are made.
The Determination of the Corrosion Rate of Steel Embedded in Concrete by the Polarization Resistance and AC Impedance Methods
Authors: Andrade C , Castelo V , Alonso C , González JA
Published: December 2008

The polarization resistance Rp determination has been widely used by the authors to measure the corrosion rate of steel bars embedded in concrete in many different situations. The AC impedance measures have now started to be used within the same system. In the present paper, we present the way to obtain accurate data by the Rp method. Comparison of the results of Rp with the weight losses determined gravimetrically and some of the results of the corrosion rates of steel bars embedded in concrete calculated by this method are presented. Also, presented here are results of AC impedance of the reinforcements obtained through a spectrum analyzer. Additionally the different graphical methods for representing the results and the accuracy of this technique in comparison with those of the Rp method are discussed. Finally, some considerations about the use of both techniques are drawn.
Utilization of Energy Code Compliance Procedures for the Prediction of Commercial Building Annual Fuel Consumption
Authors: Worbs HE
Published: December 2008

Many state model energy codes provide, as an optional alternative to building design by performance standards, a numerical computational procedure to predict a commercial building's annual energy fuel consumption. This annual energy fuel consumption value determines if the building complies with the code energy efficiency. The physical constraints of the building are considered in the calculation—that is, the building envelope and internal heat gains involving people, lighting, equipment, and ventilation. In addition, the efficiency of the building's heating and cooling mechanical plant are also considered.

This paper will first describe the computational procedures, together with the imposed assumptions and limitations, and then describe how this procedure can be adapted to a computer. It is then suggested that this computer program would be valuable in determining the changes one could expect in annual fuel usage by varying certain building design parameters.

An actual representative commercial office building was then selected using the actual building design parameters as the reference building. Variation in building orientation, wall and roof U values, changes in shading and glazing values, changes in allowable ventilation levels, and changes in the efficiency of the heating and cooling mechanical heating, ventilating, and air-conditioning system are all presented to show which ones exhibited a large sensitivity to overall building energy usage. The results will allow the design engineer to make some general conclusions as to which factors are most intensive from an energy conservation point of view.
Design Criteria for Underground Insulated Piping Systems
Authors: Govan FA , Demetroulis NM
Published: December 2008

The U.S. Government encountered a series of major failures of underground heat distribution systems in the early 1950s. A task force of engineers from nine federal construction agencies was formed, under the auspices of the National Academy of Sciences, to determine the cause of the failures, to develop design criteria for new systems, and to recommend their implementation.

This paper details the results of those investigations and discusses the specific design criteria for each system included in the study.
In Situ Measurement of Wall Thermal Performance: Data Interpretation and Apparatus Design Recommendations
Authors: Modera MP , Sherman MH , de Vinuesa SG
Published: December 2008

Although the U values of many building materials have been determined by laboratory testing, the in situ thermal performance of walls, under either static or dynamic conditions, is not so well documented. This report examines the use of field measurements of heat flow and surface temperatures to determine the dynamic as well as static thermal performance of walls. The measurement strategies examined include both active devices, which generate their own heat fluxes on the wall surfaces, and passive devices, which rely on the weather to induce the required fluxes and temperature differences. Data obtained with both devices are analyzed with the simplified thermal parameter (STP) model, which was designed to characterize a wall from flux and temperature measurements rather than from assumed material characteristics. The active measurement data are also analyzed with a modified version of the STP model that takes into account lateral heat losses. Some possible sources of error for both active and passive measurement strategies are also examined, and recommendations for both measurement strategies are given.
Heat Transfer Through a Still Air Layer
Authors: Jaouen J-L , Klarsfeld S
Published: December 2008

One question is at the origin of this study—Could a still air layer be used as a reference material in interlaboratory measurements by the guarded hot plate or heat flow meter method? Such a “material,” which is easy to get, has indeed been recommended by the International Organization for Standardization (ISO) Technical Committee 163 in a round-robin test, but very few measurement results have been reported from the participating laboratories.

The authors have investigated this configuration of particular interest using a one-specimen guarded hot plate apparatus with a thermal gradient directed downwards. By studying the variation of thermal conductance as a function of air layer thickness, we have been able to determine the thermal conductivity of still air, λg, and the total hemispherical emissivity, ε, of the measurement surfaces and to compare the experimental data with the numerical results derived from a simple model, taking into account simultaneous radiative and conductive heat transfers and giving the values of λg and ε.

This study allows us to answer the initial question positively and to show the possible sources of misunderstanding in comparing and analyzing the thermal conductivity measurements from different laboratories.
Experiences in Identification of Thermal Bridging and Elimination of the Thermal Short
Authors: McCaa DJ , Pentz ED , Carre J , Infante LJ
Published: December 2008

Our experiences encompass basic laboratory studies using the guarded hot box, field identification of the building envelope defect, and correction of the problem based on proven techniques and products.

In the laboratory, a total of 24 wall configurations were tested using ASTM Test for Steady-State Thermal Performance of Building Assemblies by Means of a Guarded Hot Box (C 236-80). Comparing theoretical R versus actual R values enabled us to identify several causes of thermal shorts along with techniques to correct the defects.

This work was related to the field as we observed:

(a) thermal bridging due to construction design,

(b) insulation gaps due to workmanship defects, and

(c) inability of certain construction systems to recover from high humidity and condensation conditions.

Considerable attention was given to these factors during our introduction of two new fiberglass products. In both the retrofit and new construction field, examples illustrate how the insulation was used to correct the envelope defects as well as how to avoid the defects.
Design Considerations on Guarded and Calibrated Hot Box Apparatus
Authors: De Ponte F
Published: December 2008

The precision and accuracy of guarded and calibrated hot box apparatus have seldom been evaluated, either during the design process or at the performance check stage. Even round robins can supply little information on errors if no theory of the apparatus is available. The purpose of this paper is to consider heat transfer in the apparatus, to supply some rough practical tips to aid in understanding the apparatus performance, even though much more has to be done to reach the same level of knowledge achieved for the guarded hot plate apparatus.

Convection heat transfer is considered first. Theoretical relationships are recalled to predict local surface coefficients in natural convection. These change along specimen surfaces, inducing temperature nonuniformities along the border of the metering box. Transitions from laminar to turbulent flow are also considered, which add hardly predictable temperature fluctuations. The problem of the position of the sensors that detect air temperatures in forced convection is then analyzed.

The analysis of coupled radiation and convection heat transfer allows a definition of the maximum expected sensitivity of the apparatus to imbalance conditions.

From the theoretical description of some sources of error, guidelines may be obtained for an apparatus performance check.
Risk of Blistering of Built-Up Roofing Membranes Applied to Polyurethane Foam Insulation
Authors: Rossiter WJ , Mathey RG
Published: December 2008

The use of polyurethane foam insulation boards in low-sloped roof constructions has increased in recent years to upgrade their thermal efficiency. Built-up membranes applied directly over polyurethane foam insulation may experience greater incidence of blistering than membranes applied on other roofing insulation boards. The bubbling of hot asphalt during its application to the polyurethane insulation board can cause voids in the asphalt layer, which eventually can grow into blisters. This paper presents the results of a study to investigate the effect of application of hot asphalt directly onto polyurethane insulation boards. In addition, it discusses causes of blistering and methods for using polyurethane foam insulation boards in built-up roofing systems so as to reduce the risk of blistering.

Polyurethane foam insulation specimens, typical of those used in the late 1970s in the United States for built-up roofing construction, were included in the study. Most of the insulations contained a facing material. Hot asphalt was applied to the insulations with facings to determine the extent of off-gassing. Hot asphalt was also applied to insulations without facings, to facings removed from insulation, and to oven-dried insulations and facings to investigate the effect of the moisture content of the insulations and facings on the off-gassing.

In other tests, oven-dried and moist (“room dry”) felts were used in the preparation of built-up membranes over polyurethane boards. Delamination of the roofing specimens indicated many large voids in the asphalt layer between the polyurethane insulation and the first ply of felt. These voids were considered to increase the risk of blistering in built-up membranes applied directly on the polyurethane foam insulation. The data support previous suggestions to apply a thin layer of rigid insulation to the polyurethane foam before the membrane is applied.
Thermal Resistances of Various Concrete Masonry Wall Constructions Incorporating Rigid Plastic Foam Insulation
Authors: Strzepek WR
Published: December 2008

Series of thermal transmission tests were conducted on large wall specimens, which measured 300 by 400 cm (118 by 157 in.), using a calibrated hot box test apparatus. The wall specimens were constructed with concrete masonry units and insulated using various interior insulation systems incorporating extruded and block molded expanded polystyrene (EPS) insulation. An exterior insulated finishing system incorporating extruded EPS insulation was also evaluated. The interior and exterior insulation systems included various methods of attachment of the insulation and finish. The impact of these attachment methods on thermal resistance was studied. Thermal resistance values for the various wall constructions were determined for two different mean temperatures. For some constructions R values were calculated using a standard heat transfer methodology commonly followed throughout the construction industry. The calculated system R values were generally only slightly greater than the measured R values, but for some insulation systems the calculation method significantly overestimated the thermal resistance of the wall construction.
Thermal Conductivity of Insulants at High Temperature: Reference Materials and Standards
Authors: Klarsfeld S , Boulant J , Langlais C
Published: December 2008

Extensive work has been done on insulants at ambient temperature: standards, reference materials, and national and international interlaboratory measurements (ISO/TC 163 round robin test). The situation is more complex at high temperatures, and this paper in an attempt to clarify this complexity, taking into account the new International Organization for Standardization (ISO) draft proposal on guarded hot plate apparatus.

Using a simple model describing heat transfer through fibrous insulants, and introducing the notion of optical thickness or opacity, the study proposes a quantitative criterion to minimize the radiative transfer, in order to obtain measurement results independent of the experimental conditions (the thickness of the specimen and emissivities of the limiting surfaces).

This criterion shows the importance of optical parameters and should, from a practical point of view, help in choosing the reference materials used for checking and in making interlaboratory comparisons of guarded hot plate apparatuses.
Final Report on ASTM Committee C-8 Thermal Conductivity Ceramic Fiber Round Robin
Authors: Ober D
Published: December 2008

A 1978 round robin analysis of guarded hot plate and calorimeter apparatuses for thermal testing of ceramic fiber insulation between temperatures of 260 and 1093°C (500 and 2000°F) is reported. A significant difference between laboratories was observed in the results, even though the results of individual laboratories were reproducible. Factors to be considered in a round robin using this material are discussed, and some of the possible sources for the differences between laboratories are reviewed. The major result of the round robin was the large range of measured thermal conductivities that different laboratories are obtaining for this material.
The Business of Materials Data Banks
Authors: Martini-Vvedensky JE
Published: December 2008

This is an analysis of the business experiences of the Engineering Information Company Ltd. in the provision of MATUS, their on-line materials selection data bank. Market demand and data-base design and distribution are discussed.
RUST: A Coupon Corrosion Test Data Base for Metals and Nonmetals
Authors: Moniz BJ , Wool TC
Published: December 2008

Du Pont has devised an interactive computerized corrosion test data base called RUST, which calculates, stores, and allows retrieval of corrosion data generated at many Company sites and test laboratories. This paper describes Version 3 of RUST, which has been expanded to include data on nonmetallic and metallic coupons. It describes the formats, the computer aspects, and the methods employed to increase user acceptance.
The Use of Chemical Dispersants to Control Oil Spills in Shallow Nearshore Waters
Authors: McAuliffe CD
Published: December 2008

Oil slicks should be dispersed in shallow nearshore waters to prevent oil from stranding. Field and laboratory studies show that chemically dispersed oil causes fewer adverse biological effects, and those are transitory. Spilled oil attains an average thickness of 0.1 mm or less in an hour or two on the water surface. Thus maximum concentrations in water are 100 ppm at 1 m and 10 ppm at 10 m. Most volatile/soluble hydrocarbons that cause toxicity evaporate from the slick in a few hours. Soluble hydrocarbons under field slicks and in chemically dispersed oil plumes are generally a factor of 150 to 1 million lower than those found to cause mortality of a wide range of organisms in laboratory studies. Chemical dispersants appear to protect some organisms, apparently by reducing oil droplet “stickiness.” A relatively few mechanically dispersed crude oil droplets, compared to many chemically dispersed droplets, caused (1) increased larval abnormalities in herring egg exposures and (2) increased petroleum content in adult coho salmon tissue. Chemical dispersion of crude oil prevented (1) mortality of mature mangrove trees in Panama and (2) adverse effects on intertidal organisms in Maine and immediate subtidal organisms in the Arctic. An oil spill is large or small relative to the receiving water. Scenarios of large and small spills show that there are no environmental reasons for not using chemical dispersants. A review of control capabilities shows that spills exceeding 160 m3 (1000 bbl)/day can only be accomplished by multiengine aircraft spraying dispersant, with mechanical methods assisting in critical areas. This assumes that the oil is dispersible. If not, most oil from spills over 160 m3/day may strand on shores. To be most effective, dispersant spraying must be initiated early, meaning that preapproval is necessary. Reduced adverse environmental effects along with greater control capabilities indicate that chemical dispersants should be used even in shallow nearshore waters.
Chemical Ionization-Proton Exchange Mass Spectrometric Identification of Alkyl Benzenes, Tetralins, and Indans in a Coal-Derived Jet Fuel
Authors: Miller DJ , Hawthorne SB
Published: December 2008

The lack of appropriate standards and the similarity of electron impact (EI) ionization mass spectra shown by isomeric alkyl benzenes, indans, and tetralins often makes the identification of specific isomers impossible. Chemical ionization-proton exchange (CIPE) mass spectrometry using methanol-d1 as the reagent gas aids in their identification by determining the number of unsubstituted aromatic positions. After ionization of the aromatic ring (that is, addition of D+), only the aromatic hydrogens undergo exchange for deuterium. The number of deuterium exchanges observed allows one to assign the degree of alkyl substitution on the aromatic ring. The CIPE spectra also provide information on the position of alkyl substitution. For example, ortho and para disubstituted alkylbenzenes show a base peak (100% relative intensity) at the mass representing the exchange of all the aromatic protons compared to an intensity of 30 to 40% for meta-disubstituted benzenes. Gas chromatographic/mass spectrometric analysis of the aromatic fraction of a coal-derived jet fuel using traditional EI ionization showed that this fraction (57% by weight) was composed primarily of alkyl substituted benzenes, indans, and tetralins, but few specific isomers could be identified. The CIPE analysis allowed additional classification of approximately 50 individual alkylbenzene, indan, and tetralin isomers based on the degree of aromatic substitution.
Analysis of Coal-Derived Materials with Low Volatility by Low-Voltage, High-Resolution Mass Spectrometry in Conjunction with Direct-Insertion-Probe Techniques
Authors: Schmidt CE , Sprecher RF
Published: December 2008

A low-voltage, high-resolution mass spectrometric (LVHRMS) method utilizing direct-insertion-probe techniques for analyses of coal-derived materials with low volatility is presented. The reproducibility of the LVHRMS-direct-insertion-probe method for determining heteroatomic composition, homologous series, and carbon number distributions of coal-derived materials is demonstrated. An auxiliary method to compute the experimental masses of sample peaks is described. The application of the LVHRMS-direct-insertion-probe method to the analyses of coal extracts treated with molten caustic to remove organosulfur compounds is reported. The LVHRMS-direct-insertion-probe method described can be applied to other complex materials containing heteroatoms.
Fracture Mechanics in Two Decades
Authors: Sih GC
Published: December 2008

A brief historical and technical perspective precedes emphasizing the need to understand some of the fundamental characteristics of fracture. What the state of the art was two decades ago is no longer adequate in the era of modern technology. Observed mechanisms of failure at the atomic, microscopic, and macroscopic scale will continue to be elusive if the combined interaction of space/time/temperature interaction is not considered. The resolution of analysis, whether analytical or experimental or both, needs to be clearly identified with reference to local and global failure. Microdamage versus macrofracture is discussed in connection with the exchange of surface and volume energy, which is inherent in the material damage process. This gives rise to dilatation/distortion associated with cooling/heating at the prospective sites of failure initiation. Analytical predictions together with experimental results are presented for the compact tension and central crack specimens.
Results on the Influence of Crack-Tip Plasticity During Dynamic Crack Growth
Authors: Freund LB
Published: December 2008

Dynamic fracture processes in structural materials are often described in terms of the relationship between a measure of the crack driving force and the crack-tip speed. In this paper, ongoing research directed toward establishing a basis for such a relationship in terms of crack-tip plastic fields is described. In particular, the role of material inertia on a small scale as it influences the perceived fracture resistance of a rate-independent material is discussed. Also, the influence of material strain rate sensitivity on the development of crack-tip plastic deformations, and the implications for cleavage propagation and arrest in a material that can undergo a fracture mechanism transition is considered. The discussion is concluded with mention of a few outstanding problems in the study of dynamic fracture, including some recent experimental evidence that the traditional crack-tip characterization viewpoint of fracture mechanics may be inadequate under very high rate loading conditions.
Creep Crack Growth
Authors: Riedel H
Published: December 2008

On the background of the historical evolution of the subject area, the current knowledge on creep crack growth is reviewed. The discussion is grouped around the C* integral, which is the appropriate load parameter for describing creep crack growth in ductile materials. Crack growth by coalescence with grain boundary cavities is modeled and the lifetimes of cracked specimens are calculated by integrating the resulting laws for crack growth. Limitations to C* arise from the initial elastic-plastic material response, from primary creep, from crack-tip blunting and from widespread cavitation damage. All these bounds are shown on a load parameter map. This is a diagram in the stress-time plane indicating the regimes in which different load parameters are applicable: KI for predominantly elastic deformation; J if plasticity plays a role; C*h for primary creep; and C* for steady-state creep. Tertiary creep is included in a damage-mechanics analysis of creep crack growth. The final section discusses a few three-dimensional aspects of fracture mechanics in general and of creep crack growth in particular.
Intersection of Surface Flaws with Free Surfaces: An Experimental Study
Authors: Smith CW , Theiss TJ , Rezvani M
Published: December 2008

A series of frozen stress experiments was conducted on surface flaws of varying aspect ratios in finite-thickness plates in order to study the practical aspects of the well-known loss of the inverse square-root singularity when the flaw borders intersect the free surface. Optical data are converted into classical stress-intensity factors ignoring and accounting for the above-noted effect and compared with a well-established numerical result. Results are discussed regarding their usefulness to both the research and practicing engineer.
A Comparison of Crack-Tip Opening Displacement Ductile Instability Analyses
Authors: Gordon JR , Garwood SJ
Published: December 2008

This paper presents the results of a large test program undertaken to study ductile fracture in aluminum weldments. The main body of the experimental program consisted of a series of wide-plate tests on 10-mm-thick parent material and welded aluminum alloy center-cracked panels. In addition to the wide-plate tests, tension, and single-specimen unloading compliance, R-curve tests were conducted on specimens extracted from the various parent materials and weld metals.

The wide-plate tests were analyzed using a crack-tip opening displacement (CTOD) strip yield model, a CTOD reference stress model, and the CTOD equivalent of the J estimation scheme published by the Electric Power Research Institute. It was found that all three models provided reasonably accurate predictions of maximum far-field stress if a representative CTOD R-curve was incorporated in the analysis.
Dynamic Brittle Fracture Analysis Based on Continuum Damage Mechanics
Authors: Chen E-P
Published: December 2008

The dynamic response of materials with existing flaw structures is the subject of the present investigation. In this paper, the cracked solid is described by a constitutive model based on continuum damage mechanics. The purpose of the analysis is to show that the constitutive model can predict many of the experimentally observed phenomena in these materials. This is demonstrated by treating a sample problem. The geometry and loading condition selected for this sample problem is that of a 45-deg inclined crack, centrally situated in a concrete panel and subjected to the action of a step tensile pulse. Damage localization and tension-softening have been observed. These results and their implications are discussed.
Correlation Between 400°C Steam Corrosion Behavior, Heat Treatment, and Microstructure of Zircaloy-4 Tubing
Authors: Thorvaldsson T , Andersson T , Wilson A , Wardle A
Published: December 2008

The uniform general corrosion behavior of Zircaloy-4 has been determined in long-term autoclave tests at 400°C and modelled using the annealing parameter A concept. The cumulative effect of subsequent heat treatments in the alpha phase field after beta quenching can be given by A = ∑i ti exp (Q/RTi) where ti is annealing time, Ti is the temperature (degrees Kelvin), Q is the activation energy, and R is the gas constant.

The corrosion weight gains at prolonged corrosion testing were determined and plotted as a function of the annealing parameter. The resulting curves can be used to predict the corrosion behavior. It was found that a minimum A value, that is, heat treatment combination, has to be exceeded in order to obtain good corrosion properties since a sharp transition from bad to good corrosion behavior occurred.

Detailed microstructural investigations using mainly electron microscopy techniques were performed on material with known corrosion behavior both before and after corrosion tests. The microstructures were characterized, and intermetallic particle size distributions were measured. Special care was taken in order to measure the particle size distributions on the tube outer surfaces, that is, where waterside corrosion actually occurs. No correlation was found between intermetallic particle sizes and the corrosion behavior: It is postulated that the matrix solute concentration is more important for the corrosion properties and that silicon and perhaps iron have the largest beneficial effects.
Corrosion Performance of Zircaloy-2 and Zircaloy-4 PWR Fuel Cladding
Authors: Rudling P , Pettersson H , Andersson T , Thorvaldsson T
Published: December 2008

A variety of Zircaloy-2 and Zircaloy-4 cladding tubes with different microstructures has been manufactured. Test rods have been included in two fuel assemblies, and the assemblies have been inserted into the Ringhals 3 pressurized water reactor. Samples from the same cladding tube variants have been subjected to steam autoclave testing in the range 400 to 500°C for different exposure times and have been characterized with respect to their microstructure.

After one cycle of in-reactor exposure, the oxide thickness was thinner on stress relief annealed Zircaloy-2 rods than on Zircaloy-4 rods with the same heat treatment. Replacing the last stress relief anneal with a recrystallization anneal increased the out-of-pile corrosion resistance of the Zircaloy-4 cladding, whereas no statistical difference was seen in-pile after the first cycle. Scanning electron microscopy (SEM) measurements of the particle size distribution revealed only small differences in sizes between the cladding types.

The results from the autoclave tests done at 400°C/200 days, 410°C/28 days, 430°C/30 days, and 500°C/24 h indicated that the long-term 400°C test is capable of predicting the in-reactor behavior, whereas the 500°C as expected was found to be related to the nodular corrosion mechanism. The 430°C test seemed to be in a transition range from the uniform to the nodular corrosion mechanism. Short-term testing at 410°C resulted in the same ranking of materials as the long-term 400°C test indicating that a 410°C test could be used to predict the in-reactor behavior in a relatively short time.
Corrosion Performance Ranking of Zircaloy-2 for BWR Applications
Authors: Rudling P , Machiels AJ
Published: December 2008

The waterside nodular corrosion of Zircaloy cladding in boiling water reactors (BWRs) remains a primary concern in fuel performance because of (1) recurring fuel failures in several BWRs and (2) the current trend in the nuclear industry towards higher fuel burnups. The failures might be avoided if there were a reliable way of sorting claddings, so that only cladding that is highly resistant to corrosion would be used. In-reactor corrosion testing of cladding tubes is expensive and time-consuming, and consequently, there exists a strong incentive to develop a short-term, out-of-pile corrosion test that is able to predict cladding corrosion behavior for BWR applications.

It is shown in this paper that a high-pressure steam autoclave test performed at 520°C for 24 h is capable of classifying the in-reactor nodular corrosion properties of the fuel cladding. The effects of test temperature, sample surface treatment, and oxygen and hydrogen content in the steam on corrosion performance are documented.
Heterogeneous Scale Growth During Steam Corrosion of Zircaloy-4 and 500°C
Authors: Charquet D , Tricot R , Wadier J-F
Published: December 2008

Various Zircaloy-4 materials have been exposed in steam at 500°C for times between 2 and 72 h. The observations indicate that two major factors govern scale growth: crystal orientation and precipitate density. Furthermore, the study of coarse grained materials shows that when two adjacent grains corrode at very different rates, the catastrophic oxidation of one of them has little tendency to propagate into its more highly resistant neighbor. This “barrier” effect to the lateral extension of local regions of thick scale is particularly efficient when the individual grains have markedly dissimilar characteristics. This is especially true for acicular and alpha-beta structures.

In equiaxed structures, the corrosion rate depends on both structure and texture. Structures with very fine precipitates (ϕ > 0.1 μm) show excellent nodular corrosion resistance. On the contrary, when the precipitates are coarse (ϕ < 0.2 μm), the nodular corrosion resistance is very poor. In both of these cases, the texture has little influence. However, for intermediate precipitate dimensions (0.1 μm < ϕ < 0.2 μm), the effect of orientation becomes preponderant. If a grain whose orientation favors rapid corrosion is surrounded by more resistant neighbors, then the localized corrosion will not develop. On the contrary, if the adjacent grains are also propitiously oriented for enhanced oxidation, a critical nucleus size is attained and the resulting corrosion nodule can continue to grow. This mechanism assumes that the initiation site includes a minimum number of grains.
Intermetallic Precipitates in Zirconium-Niobium Alloys
Authors: Meng X , Northwood DO
Published: December 2008

Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) have Seen used to study the composition and structure of intermetallic precipitates, principally those containing iron and chromium, in Zr-2.5wt%Nb pressure tubing and Zr-lwt%Nb fuel sheathing. The Zr-lwt%Nb fuel sheathing contained Zr(FeCr)2 Laves phase precipitates with either the C-14 hexagonal or C-15 cubic structure. Orthorhombic Zr3Fe precipitates were also tentatively identified. Tetragonal Zr2Fe precipitates were found in Zr-2.5wt%Nb pressure tubing containing 700-ppm iron. The volume fraction of Zr2Fe was very small (<0.1% on an area basis) and was much smaller than the volume fraction of Zr(FeCr)2 precipitates in Zr-1wt%Nb.

The difference in type and volume fraction of iron-containing precipitates in Zr-lwt%Nb and Zr-2.5wt%Nb despite similar iron and chromium contents is tentatively attributed to the different volume fractions of the β-phase. Iron is a β-stabilizer and concentrates in the β-phase. The Zr-2.5wt%Nb alloy, which contains the higher volume fraction of β-phase, takes in more iron in solution in the β-phase thus leaving less to precipitate out as an intermetallic.
Oxidation Kinetics and Auger Microprobe Analysis of Some Oxidized Zirconium Alloys
Authors: Ploc RA
Published: December 2008

Oxidation kinetics at 300°C in dry oxygen of 0.5 wt% binary alloys of iron, nickel, and chromium in zirconium were determined for several surface preparations. Further, chemical profiles of the oxides as they existed on the matrix and on the precipitates were obtained by sputtering and Auger electron analysis. The appearance of “breakaway” oxidation was controlled by the surface finish of the alloy, a variable that could be used to eliminate the phenomenon for all alloys except the Zr/Ni binary, which required β-quenching to accomplish the same purpose.
The Effect of Temperature on the Irradiation Growth of Cold-Worked Zr-2.5 Nb
Authors: Holt RA , Fleck RG
Published: December 2008

Specimens of cold-worked Zr-2.5% Nb pressure tube material fabricated by several different routes have been irradiated unstressed in the Dido reactor at Atomic Energy Research Establishment (AERE) Harwell to fluences up to 7.5 × 1025 n/m2, E & 1 MeV (about 18 dpa). Their irradiation growth behavior has been investigated as a function of temperature in the range 553 to 623 K.

The growth strains and strain rates in the axial direction are found to decrease with increased irradiation temperature even though the long-term growth rate in the axial direction may be either negative or positive. The effect of temperature on the transverse growth is the reverse of the effect on axial growth. Increasing the irradiation temperature incrementally from 553 K by 30 or 70 K produces a transient negative growth strain in the axial direction which increases in magnitude with the magnitude of the temperature increment. Decreasing the temperature from 623 or 583 K produces a transient which is approximately the reverse of that observed with a temperature increment.

These results are discussed in terms of a model in which growth is driven by the size interaction (SI) between point defects and dislocations and by the difference in diffusional anisotropy (DAD) between vacancies and self interstitial atoms (SIAs). Several microstructural features compete as sinks for the vacancies and SIAs produced by the fast neutron flux. It appears that changing the temperature in this range may change the balance in the net point defect fluxes to the sinks because of different temperature dependencies of the SI and the DAD.
Field Evaluation of French Self-Boring Pressuremeter Paf 76 in a Soft Deltaic Louisiana Clay
Authors: Canou J , Tumay MT
Published: December 2008

The results of a field investigation carried out with the French self-boring pressuremeter PAF 76 in a soft deltaic clay deposit located in south Louisiana are presented. The in-situ test is performed using an electronic control and data acquisition system, monitored by an HP85 microcomputer. A brief description of the equipment used, the general in-situ test procedure, and the approach used for the interpretation of a standard expansion test are presented. General characteristics of the deposit as well as an outline of the testing program are summarized. The standard pressuremeter characteristics are then plotted versus depth and compared with results obtained using other testing methods at the same site (cone penetrometer, dilatometer, triaxial test). This comparison shows that the self-boring pressuremeter yields shear strength and elastic modulus values much higher than the other classical methods, which agrees with previously reported observations.
Conventional Parameters from Pressuremeter Test Data: Review of Existing Methods
Authors: Felio GY , Briaud JL
Published: December 2008

The solution for the expansion of an infinitely long cylindrical cavity in a soil mass, based on given constitutive laws, allows to obtain “conventional” soil parameters such as the undrained shear strength or the angle of internal friction based on pressuremeter test results. The pressuremeter test also allows to obtain adequate values of the in-situ horizontal stress in the soil when proper insertion of the probe (little disturbance) is achieved. The existing methods to obtain these parameters are discussed for preboring and selfboring pressuremeter units.
Formulation of Highly Active Cobra Postemergent Herbicide
Authors: Keim WA
Published: December 2008

Cobra herbicide shows significant postemergent activity on important broadleaf weeds while exhibiting tolerance on soybeans. Cobra herbicide field studies have been made to evaluate the effects of the formulations. The formulation effects are concerned with the delivery of Cobra herbicide to the plant surface and the herbicide's physical nature on the plant surface. The studies were concerned with crop injury as well as weed control. Cobra herbicide can be formulated as an emulsifiable concentrate; therefore, the major interest in Cobra concerns the surfactant and solvent effects. In addition, treatments were made with crop oil and soybean oil adjuvants, a special silicone surfactant, and a potentially “soft” Cobra wettable powder formulation. The results can be explained by simple physical chemical reasoning.
Optimizing Physical Properties of Diluent Oils for Maximum Target Deposition of Ultralow-Volume Spray Droplets Under Laboratory Conditions
Authors: Sundaram A
Published: December 2008

The influence of absolute viscosity, surface tension, volatility, apparent viscosity-shear rate relationship, and distillation point on droplet size spectra and deposit characteristics was investigated for a wide range of petroleum and vegetable oils used in pesticide sprays, using Kromekote cards and glass plates for droplet collection. Air samplers were also used simultaneously to assess the airborne concentrations of the materials. The results indicated an increasing trend in absolute viscosities and surface tensions, and a decreasing trend in volatilities of the diluent oils, as their distillation points increased. However, the relative rate of increase in absolute viscosities was greater than that in surface tensions. As a result, the inverse relationship between viscosity and volatility was much more pronounced than the one between surface tension and volatility. The apparent viscosities of the volatile oils at high shear rates were very much lower than those of the nonvolatile oils, indicating a marked difference in the intermolecular forces of attraction. The droplet size spectra, and thus the deposit characteristics, and airborne concentrations of the diluent oils varied depending on their absolute viscosities, volatilities, and apparent viscosities at high shear rates. The droplet size spectra of the highly volatile oils consisted of very small sizes, and as the volatility decreased gradually, a progressive increase in the droplet sizes and deposits was observed. The most satisfactory combination of droplet size spectra, droplets per unit area, and spray volume deposits, and that with the least amounts of airborne concentrations, was obtained with the Dowanol TPM solvent, which was also the least volatile of the eight volatile oils studied.
Insecticide Spray Measurements Using Hot-Wire Technology
Authors: Mahler DS
Published: December 2008

The use of hot-wire technology to measure the size distribution of droplets contained in liquid sprays has recently been expanded to include certain specific insecticide materials in addition to previously investigated liquids such as water and mineral oil. Classes of liquids associated with different calibrations can be identified by a relatively straightforward measurement of the surface tension. Thus, it is not necessary to perform a detailed optical calibration of every material. Also discussed are the size ranges of various liquids, details of the droplet/wire interaction, aerodynamic effects, effects of the longitudinal temperature distribution, and eccentricity. Uses of hot-wire technology and its advantages over optical techniques and the older slide-wave techniques will be discussed, along with current commercially available instruments and new instruments being developed.
A Low-Volume Microtube In-Furrow Sprayer
Authors: McCracken A
Published: December 2008

This paper describes a new application system that uses specific lengths of microtubes to deliver low volumes of insecticide into open seed furrows at the time of planting. The system was developed as an alternative for specific product/crop pest combinations and offers greater accuracy and safety than conventional methods such as seed treatment, band spraying, or granular application.

The microtube applicator uses small-bore plastic tubing with a 0.75 to 2.00-mm (0.03 to 0.08-in.) internal diameter to meter the chemical solution directly into the soil. Specific lengths of microtube of specific bore sizes are selected to permit the use of low volumes of water, as low as 10 L/ha on wheat.

The tubes are attached to the seed coulters of the planter, and the chemical solution is pumped using a 12-V pump with a pressure regulator system or a ground-driven metering pump. Depending on the chemical concentration and the rate required, tests have confirmed that the product may be applied undiluted or mixed with water, using a mixing valve, prior to its discharge through the microtubes.

Effective tests have been conducted in Australia and the United States, and current developments include closed-system handling of the chemical.
Erosivity of Coal Particles in Coal-Solvent Slurries
Authors: Levy AV , Jee N , Sorell G
Published: December 2008

An investigation of the erosivity of particles of several different coals and respective vacuum bottoms from the Exxon Donor Solvent (EDS) coal liquefaction pilot plant of the Exxon Coal Liquefaction Process (ECLP) was carried out. Kerosene and tetrahydrofuran (THF) were used as the liquids in slurries containing 30 weight % particles. The particles were of several sizes, shapes, integrities (fracture strength), and ash contents. It was determined that the primary factors having a direct effect on erosivity were particle size and ash content/composition. Particle shape and resistance to fracturing upon impact had important secondary effects. All of these factors are interrelated and can counter each other under certain conditions. Slurry pot testing proved valuable as a reproducible method for comparative erosion studies, but should not be relied upon to produce quantitative erosion data for equipment design purposes.