bluuebunny/crossref_metadata_2025 huggingface dataset:
Developmental Researches on the Lightweight Structure for Future Satellite in the National Development Agency of Japan
Authors: Kawashima T , Yamamoto M , Yamawaki T , Yoshimura Y
Published: December 2008

In recent years we are making some developmental studies on lightweight spacecraft structure and several lightweight components in National Space Development Agency of Japan (NASDA). Presented here are the test results of the structural components which were made of graphite fiber reinforced composites, carbon fiber reinforced composites, and aluminum alloy plate and honeycomb core, etc.

We describe the three items as well as the manufacturing process. First, graphite-epoxy tube trusses were manufactured and tested for use as struts and main frames of the satellite structure. Second, lightweight honeycomb panels were designed and fabricated to provide spacecraft structural components which are used as some equipment panels or stiffened panels. Third, lightweight solar panel was developed and tested for 3-axis stabilized spacecraft with sunoriented solar arrays which are expected to meet the power requirement of more than 1.8 kW. The panel has successfully been tested under acoustic noise environment, thermal cycling, and sinusoidal vibration, and thus qualified for space applicability.
On the Streamline Specimen for Tension Testing of Composite Materials
Authors: Oplinger DW , Parker BS , Gandhi KR , Lamothe R , Foley G
Published: December 2008

Tensile and shear stress concentrations have been found in prior work to degrade the performance of tension test specimen designs in current use. In the particular case of tabbed specimens there is need for an alternative specimen design to avoid problems with tab failures and loss of tabs when testing in adverse environments. The streamline shape which is described here provides such an alternative. This paper discusses the theoretical background to the streamline shape, together with results of studies in which its performance is compared experimentally with other specimen types, especially tabbed specimens, in both static and fatigue testing environments.
Effects of Vacuum and Temperature on Mechanical Properties of S2-Glass/Epoxy
Authors: Thomas Hahn H , Hwang DG , Chin WK
Published: December 2008

Mechanical properties of an S2-glass/epoxy composite have been characterized at room temperature and at 100°C in vacuum. The latter was to simulate the flywheel service environment. The epoxy was DER 332/Menthane Diamine (100/24.5), and the composite was filament-wound and cured 2 h at 150°C. It has been found that the composite continues to lose weight even after ∼150 days of conditioning at 100°C in vacuum. The weight loss is accompanied by a change of color from translucent white to brown. The present composite shows less moisture absorption than most graphite/epoxy composites for aerospace applications. The 100°C/vacuum environment has only a minor effect on the mechanical properties, both static and fatigue. However, the moisture desorption in vacuum increases residual stresses and leads to ply cracking in laminates. The logarithmic fatigue life is linearly related to the fatigue stress, and the fatigue strength at 106 cycles is ∼20% of the average static strength at room temperature and also at 100°C in vacuum. However, the corresponding fatigue strength at 100°C in air is below 20% of the average static strength. Whereas the static failure is brush-like, the fatigue failures at stresses lower than ∼60% of the static strength are slivery. The failure mode at the elevated temperature tends to be more slivery than at room temperature. The composite is susceptible to modulus reduction in fatigue without any apparent longitudinal splitting. The maximum modulus reduction before failure increases with decreasing stress level.
Determination of a Constitutive Law for Salt at Elevated Temperature and Pressure
Authors: Senseny PE
Published: December 2008

A constitutive law for natural rock salt is given that describes the relationship among strain rate, stress rate, stress, temperature, and time. Tests required to evaluate the constitutive parameters are identified, and procedures for performing these tests are described. Results are presented from a series of tests performed on bedded salt from the Palo Duro basin. These results are used to evaluate the constitutive parameters, yielding a constitutive law suitable for predicting stresses and deformations in a nuclear waste repository or other engineered structure in salt.
A Method for Emulsion Optimization Through Computerized Regression Analysis
Authors: Lohr JE
Published: December 2008

Alternative physical properties of emulsions were explored to define a linear equation which was correlated to emulsion stability so that liner regression techniques could be applied. Analysis of the oil phase separation by Karl Fischer titration, oven solids, and anionics response provide linear data sufficient for predicting results. A method for entering the composition of emulsifiers into currently available software for regression analysis by using ratios of significant components is discussed.
Injection of Chemicals for Subsurface Drip Irrigated Cotton
Authors: Tollefson S
Published: December 2008

Since 1980, Sundance Farms, Inc. has successfully grown three crops of cotton and one crop of wheat using subsurface drip irrigation systems. In evaluating drip on a commercial basis we have been able to increase yields by 36% to 50% and reduce total water use by more than half.

A large part of this success can be attributed to the injection of chemicals through the drip systems. Mechanical injectors have enabled the application of N-P-K fertilizers and chelated micronutrients directly to drip systems resulting in considerable flexibility and greater application efficiency. In addition, exceptional nematode control has been achieved with fumigants and contact nematicides siphoned into the systems. Injection systems for the introduction of sulfuric acid into pressurized drip systems has also been developed. The acid treatments have in part been responsible for three times the reduction of soluble salt levels in the soil. The continuous injection of acid has also helped in the maintenance of drip tubes by eliminating salt precipitation around the emitters.
The Laboratory for Pest Control Application Technology (LPCAT): A New Interdisciplinary Approach for Solving a Difficult Problem
Authors: Hall FR
Published: December 2008

Improvement of pesticide delivery appears necessary because of environmental concerns, integrated pest management (IPM) programs, economics, and increasing efficacy of new pest control agents. LPCAT research efforts in dose targeting include development of an intermittent sprayer, pesticide/target placement studies, and observations on pesticide formulation and droplet density effects on mite behavior. Significant savings in pesticide usage can result from correct pesticide targeting. However, further savings will require additional cooperative research efforts on basic mechanisms of pesticide delivery, impingement, and dose responses of pests.
Crack Shape Monitoring Using A-C Field Measurements
Authors: Topp DA , Dover WD
Published: December 2008

A multi-central processing unit (CPU) computer network has been installed at University College London for fatigue tests and automatic inspection work. This system is described, together with a newly developed alternating-current field measurement inspection system for crack measurement, in use on some novel stress corrosion tests. The complete system makes it possible to conduct tests where the crack shape evolution can be monitored.
A Low-Cost Microprocessor-Based Data Acquisition and Control System for Fatigue Crack Growth Testing
Authors: Sooley PM , Hoeppner DW
Published: December 2008

The requirements for obtaining economic fatigue crack growth data from the threshold regime to instability in inert, gaseous, elevated-temperature, and aqueous environments necessitate the development of remote crack growth monitoring techniques. Two of these processes used extensively are the compliance method and the potential-drop method.

The performance of a microprocessor-based machine controller and data acquisition system utilizing the d-c potential-drop method of monitoring crack length is presented. The development of software for performing K-increasing and threshold tests and their compliance with the present ASTM standards are discussed. The successful development and use of the machine are shown by the results obtained during round-the-clock testing for acquiring crack growth data for a titanium alloy.
Automated Technique for R-Curve Testing and Analysis
Authors: Jolles M
Published: December 2008

The crack growth resistance curve (R-curve) appears to be a viable approach to elastic-plastic fracture analysis. An automated technique for R-curve testing and analysis provides the opportunity to enhance accuracy and resolution while reducing variability due to influences of the test operator and data analyst. A microcomputer-based test control, data acquisition, and analysis system is described. Details of the test hardware, procedures utilized for the conduct of R-curve experiments, and methods for the analysis of the data are presented. The results demonstrate the quality and reproducibility obtained by the technique.
Computerized Single-Specimen J-R Curve Determination for Compact Tension and Three-Point Bend Specimens
Authors: Jablonski DA
Published: December 2008

A computer-controlled test system was developed to measure J-R curves and JIc on compact tension and three-point bend specimens. The crack length was measured by unloading compliance. Improved crack length accuracy was obtained by amplifying the load and crack opening displacement (COD) signals by factors of 10 to 20 before the unloading. Crack length accuracy was further improved by collecting 500 data pairs on unloading using a fast data acquisition method. In the compact tension specimen, crack length and load-line displacement were measured with a load-line COD gage. In the three-point bend specimen, load-line deflection was measured using the crosshead deflection corrected for specimen and test fixture stiffness. An error analysis was performed to determine the crack length errors. The analysis showed the beneficial effect of using load and COD ranging to reduce the crack length errors.

J-R curves were measured on 17-4-Ph stainless steel heat treated to 948 MPa yield. The J-R curves were measured on two specimen geometries, compact tension and three-point bend, using four starting a/w ratios from 0.65 to 0.80 and three side groove depths, 0%, 12.5%, and 25%. The test results showed that in specimens with side grooves of 12.5% and 25%, the measured JIc-values were independent upon both specimen geometry and starting a/w ratio. The material tearing modulus, Tmaterial, was found not to be a material property since its value depended upon specimen geometry.
Thermal Conductivity Measurements with the Plate Apparatus: Influence of the Guard Ring Width on the Accuracy of Measurements
Authors: Bode K-H
Published: December 2008

The temperature field in circular and square plate test specimens is calculated and thereby the error from the heat exchange at the outer edge of the guard ring derived for single and double plate devices under conditions of isothermal hot and cold plates and ideal thermal contact. The error is shown to be proportional to the reduced temperature difference (difference between the mean specimen and the ambient temperatures divided by the difference between the hot and cold plate temperatures) and the margin of error, therefore, can be optimally reduced by an appropriate adjustment in the ambient temperature. Experiments on an extruded foam confirm the results of the analytical calculations. Diagrams and tables which are developed on the basis of the above derived relationships, make possible estimation of margin of error for different measuring arrangements for plate devices of usual sizes.
Industrial Systems Testing Using Heat Flux Transducers
Authors: Whitaker TE
Published: December 2008

A heat flux transducer was calibrated on a guarded-end pipe tester and inserted under the jacket of an outdoor steam-heated pipe. The pipe was designed to allow the condensate to be collected and measured. The heat loss was calculated from the condensate volume and the thermal properties of steam. When compared with the heat loss measured by the transducer, agreement was within 6%.

The transducer output was recorded continuously over a one-year period. The average was obtained over a 24-h period to allow for comparison with average ambient weather conditions. Typically, the transducer output was inversely proportional to the average ambient temperature. Increasing wind speed reduced the surface temperature of the pipe and increased the average transducer output (heat loss).

Data are presented showing typical readings averaged over 1 h, 24 h, and two months. The data indicate that a heat flux transducer can be used to measure heat loss adequately in an industrial environment.
Heat Flow Sensors on Walls—What Can We Learn?
Authors: Flanders SN
Published: December 2008

This paper addresses the validity of employing heat flow sensors (HFSs) on the indoor surfaces of building walls to determine thermal characteristics. It also reports on the results obtained in the field.

Some of the factors affecting HFS measurement accuracy (together with a likely percentage standard deviation attributable to that factor) are as follows: (a) the conductivities of HFS and its surroundings (3%), (b) convection mode changing over the sensor, causing a +21% bias (26%), (c) the mismatch of HFS absorptivity with the surroundings (6%), and (d) thermal contact of the HFS with the surface (1%). A propagation-of-errors analysis indicates that the resulting standard deviation of an HFS measurement would be approximately 10% of the mean of the measurements.

The R-value measurements of 20 buildings at four Army bases and installations demonstrated that the technique is repeatable—the same data time series with different start times results in the same R-value, side-by-side sensors give the same results (±5%), and different buildings of the same construction give similar results. Buildings whose construction was verified by boring into the wall gave measurements that agreed within 10% with the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) calculations. Also, convection cells were very evident, even in insulated frame walls, necessitating a traverse of sensors from the top to the bottom of the wall.

With appropriate awareness of potential error sources, surface-mounted HFSs can render reasonable results.
Fabrication and Certification of Electroformed Microhardness Standards
Authors: Kelley DR , Johnson CE , Lashmore DS
Published: December 2008

A commonly quoted characteristic of a material is its hardness. Accurate measurements of this characteristic require the use of precise standards to verify that the testing instrument, procedures, and comparisons with the results of another laboratory are accurate; however, it is recognized that currently available standards vary considerably in hardness from point to point across the surface. Electroplating technology was utilized to fabricate new microhardness standards. This technology provides a means for obtaining uniform hardness by close control of process variables which determine grain structure and composition.

Two microhardness standards are now in production—one with a hardness of ∼125 kg/mm2 and the other at ∼600 kg/mm2. The hardness values are certified at loads of 0.245, 0.490, and 0.981 N (25, 50, and 100 gf) with both Vickers and Knoop indenters. These electroplated materials have standard deviations in hardness, particularly at low loads, that are significantly better than the available standards. The fabrication of the new standards, their certification procedures, and testing instrument characteristics are discussed.
Indentation Test for Polymer-Film-Coated Computer Board Substrate
Authors: Engel PA , Derwin MD
Published: December 2008

The phenomenon of indentation in coated substrates was checked by applying conical and spherical indenters of various geometries in a wide load range. Microscopic observation and cross sectioning of the indentations revealed three concentric regions: the inner contact zone, the indentation crater, and the debonding zone. The latter is formed if insufficient adhesion between the film and substrate gives way to the normal tensile stress on the interface, outside the contact area. In the contact zone the film is permanently compressed, and the indentation, accompanied by sinking in, is fundamentally a plastic deformation phenomenon. An analytical method is presented for estimating the “hardness” (defined as load per indentation crater area) of coated substrates from indentation and deflection measurements of the uncoated substrate plus a single deflection measurement of the coated substrate. Hardness curves (hardness versus force curves) for various indenters are plotted and compared.
An Industrial Approach to Quality Assurance—Boring? You Bet! But Not If You Want to Make Money
Authors: Ziegel KD , Knox RE
Published: December 2008

Quality assurance is that corporate function that negotiates and then monitors the implicit (and explicit) contract between the industrial customer and the manufacturer. Implementation of that function can and will depend on the structure of the corporate organization and on the nature of the industrial product. In the elastomers industry, we face a particular challenge: the products we manufacture must undergo not only a change in physical shape (forming by extrusion, molding, and so forth) but also a chemical transformation known as vulcanization. Quality assurance in the elastomers industry requires more complex testing and release procedures than are required for nonvulcanizable thermoplastics; test results are, in addition, highly dependent on compounding, heat history, and processing variability.

To meet these technical challenges, we have elected to organize our quality program in a hybrid fashion with responsibility for quality control (release and classification of product) located at the individual manufacturing sites and with quality assurance (negotiation of the customer/manufacturing contract) located in a single centralized laboratory equipped with up-to-date forming and vulcanizing equipment designed to simulate the customers' specific industrial processes. This approach maintains primary quality responsibility in the manufacturing organization, eliminates duplication of effort when several manufacturing sites are involved, and provides an effective representation of the specific needs of the customer and the market. Born of necessity in the elastomers industry, this concept of quality assurance/control can serve as a model for similar programs for other industrial products.
The Role of Interlaboratory Test Programs in Quality Assurance
Authors: Barnes JD
Published: December 2008

A program for assuring the quality of products made from plastics is only as valid as the test methodology that supports it. Test methods can be characterized as to their repeatability and reproducibility. Both of these measures describe the level of precision, or agreement among test results, obtained when a test method is used to characterize a product, be it a raw material or a finished part. ASTM requires that each test method in the ASTM Book of Standards be provided with a statement of precision and accuracy. This paper describes some recent efforts within Committee D20 on Plastics to assess the precision of two test methods. The results are analyzed using ASTM Practice for Conducting an Interlaboratory Test Program to Determine the Precision of a Test Methods (E 691).

The implications of the measured precision of the test methods for their use in quality assurance activities are described.
Quality Assurance by Means of Thermoanalytical Routine Methods
Authors: Widmann G
Published: December 2008

Thermal Analysis was restricted to the research laboratories in the past. To enable its routine use, additional demands are made on the instrumentation: exactly reproducible test conditions, automatic evaluation of final results, and ease of operation are the most important additional demands. These features are covered by modern microprocessor-controlled instruments that work with saved test methods. A “saved test method” is the sum of the instructions that define the execution of the measurement and its evaluation, whereby these instructions are stored permanently for repeated use. Coupling of single methods enables the automatic execution of complicated temperature programs as well as several different evaluations of a curve (for example, glass transition temperature and heat of crystallization). With the example of the determination of the linear thermal expansion coefficient α, of a printed circuit board, the development and the use of a saved method will be discussed. The obtained standard deviation of α is about 6%. The standard deviation of the glass transition temperature amounts to 2.1°C. All measurements were performed with a Mettler TMA40.
Hydrogen Embrittlement of Zimaloy: A Cobalt-Chromium-Molybdenum Orthopedic Implant Alloy
Authors: Edwards BJ , Louthan MR , Sisson RD
Published: December 2008

Controlled potential, slow strain rate tests of Zimaloy (a cobalt-based orthopedic implant alloy) in Ringer's solution (a physiological saline solution) at 37°C show that hydrogen absorption may degrade the mechanical properties of that alloy. Potentials were controlled so that the tensile sample was either cathodic or anodic with respect to the metal's free corrosion potential. Hydrogen was generated on the sample surface when the specimen was cathodic, and dissolution of the sample was encouraged when the sample was anodic. The results of these controlled potential tests showed no susceptibility of this alloy to stress corrosion cracking at anodic potentials.

However, when samples were tested at a potential of 150 mV cathodic to the free corrosion potential, the difficulty was decreased by 37%. The 150-mV shift in potential was selected because that was the potential observed when this alloy, in a creviced condition, was placed in Ringer's solution for two months. Support for this reduction in ductility during the cathodic exposures was obtained by testing the hydrogen compatibility of the alloy. Samples charged in gaseous hydrogen showed significant losses in ductility. The most severe hydrogen charging (207 MPa at 300°C for ten days) reduced the tensile ductility to 0% reduction in the area at fracture while less severe charging (6.9 MPa at 200°C for seven days) caused a 50% decrease in ductility. Results of these tests indicate that this cobalt-based alloy suffers a significant loss in ductility under conditions that may arise if a creviced sample is exposed to saline solutions.
Properties and Characteristics of Cast, Wrought, and Powder Metallurgy (P/M) Processed Cobalt-Chromium-Molybdenum Implant Materials
Authors: Kumar P , Hickl AJ , Asphahani AI , Lawley A
Published: December 2008

Cobalt-chromium-molybdenum alloys have been highly successful as implant materials due to their corrosion resistance to body fluids, excellent mechanical properties, and biocompatibility. Limitations associated with the conventional processing of these alloys, such as precision casting or casting followed by hot working, have been overcome recently by the use of powder metallurgy (P/M) processing techniques. This paper presents results from an on-going program of research on cobalt 26 to 28Cr, 5 to 6Mo alloys.

Cast, conventionally hot-rolled, and P/M-processed materials were evaluated. The effect of cooling rates in the range of 10 to 104°C/s was investigated. The results of tension, localized corrosion, corrosion fatigue, and stress corrosion cracking tests are discussed.
Fretting Corrosion of Plates and Screws: An In Vitro Test Method
Authors: Brown SA , Merritt K
Published: December 2008

A laboratory fretting corrosion simulator was constructed for studying the fretting corrosion of the contact areas between screw heads and plate hole countersinks of surgical implants used for fixation of broken bones. The system was constructed so that the tests could be done under sterile conditions, thus permitting the use of proteinaceous as well as conventional electrolyte solutions. Studies were done to investigate the effects of contact stress as controlled by screw torque, the effects of blood serum proteins, the effects of proteins at different solution pH values, and the effects of mixing metals. The alloys used were Type 316L stainless steel, MP35N, titanium, and titanium-6AI-4V. The results demonstrated that statistically significant data can be obtained with a small number of specimens. The rate of fretting corrosion was independent of load over a limited range. The presence of proteins significantly reduced the fretting corrosion of stainless steel and MP35N, had no effect of Ti-6AI-4V, but increased the fretting corrosion of titanium. In solution with pH values acidic to its isoelectric point, the protein albumin had a negligible effect; whereas at solution pH values basic to its isoelectric point, fretting corrosion was reduced. Mixing of metals had an effect on the fretting corrosion of MP35N and titanium, but no effect on stainless steel.
Fatigue of Ball-Joint Rods for External Fixation
Authors: Donald GD , Seligson D , Brown CA
Published: December 2008

Twenty-three Hoffmann ball-joint rods were subjected to sinusoidal loads, each at approximately constant amplitude, between ±400 and ±975 N at a frequency of 5 Hz. Ball-joint rod compliance was plotted against number of cycles for each specimen. The point of component failure was defined as an increase of compliance of 5% from its initial value. Fractographic methods were employed to substantiate a similarity of failure mode in specimens tested and a clear difference from non-tested specimens taken to failure. Experimental loads and number of cycles to failure were well within the clinical range. The fatigue limit of the ball-joint rods is less than 400 N (550 N/mm2). The likelihood of a given component failing is not predictable by inspection or manual manipulation.
Multispecies Tests: Research Needs to Assess the Effects of Chemicals on Aquatic Life
Authors: Giesy JP
Published: December 2008

Aquatic multispecies tests are an extremely flexible and powerful tool in aquatic ecology, especially in the study of the fates and effects of xenobiotics, but are not amenable to the type of protocol development and precision required to be part of a formal hazard assessment scheme. Such methods are completely antithetical to the most efficient use of multispecies tests, which is the ability to design a system to elucidate particular mechanisms and interactions in specific ecosystems. One goal of hazard assessment schemes is to remove the subjectivity of individual researchers from the process. Multispecies tests will not achieve this goal. Instead, aquatic multispecies tests of all sizes and configurations should be used by researchers to answer questions posed about the behavior and effects of xenobiotics in aquatic environments. Therefore, rather than designing experiments to test whether multispecies toxicity tests are accurate or replicable they should be used to elucidate mechanisms and make tests of relevant hypotheses within the overall framework of aquatic ecotoxicology. Because of the diversity of interactions among organisms and xenobiotics and the environments on which they exist, one will never be able to absolutely establish the accuracy of multispecies tests. Simply because multispecies tests are more complex does not mean that they are more realistic or have more predictive power than single-species tests. In fact, they may be more prone to artifacts. There is no evidence to suggest that multispecies toxicity tests, as a class, are more sensitive than the more traditional method of establishing criteria from final chronic values, based on single-species tests. More research on multispecies replicability is not necessary. Replicability is a statistical problem rather than an intrinsic property, and appropriate tests and designs are available to determine the relative variability, and therefore the sensitivity of laboratory-scale multispecies test, and they allow the appropriate number of stratified replications to be determined to make the test sufficiently replicable to make precise conclusions. Multispecies tests may be more efficient than conducting several single-species tests because of a greater range of sensitivities of test organisms, however, this has not been established. The most useful types of multispecies toxicity tests will be in-situ-type systems where some replication can be accomplished in a more realistic system or multispecies tests of mesocosm-scale. Further research is needed in the area of validation studies of in-situ systems.
Field Confirmation of a Laboratory-Derived Hazard Assessment of the Acute Toxicity of Fenthion to Pink Shrimp, Penaeus duorarum
Authors: Borthwick PW , Clark JR , Montgomery RM , Patrick JM , Lores EM
Published: December 2008

Field studies were conducted to determine if laboratory protocols accurately predict shrimp mortality under field conditions. To evaluate the applicability of laboratory data, fenthion, a mosquitocide, was applied to coastal black rush (Juncus roemerianus) marshes in several truck-mounted ultra-low volume (ULV) adulticide operations and by direct application at the larvicide rate. Caged pink shrimp (Penaeus duorarum) were deployed in floating compartmented cages and observed frequently over a 24-h period for mortality. Water samples collected for gas chromatographic quantitation characterized the exposure concentration regime and fate of fenthion at the field sites. Field data were compared to laboratory acute toxicity data from ASTM standard practice flow-through tests. The acute flow-through 96-h LC50 of 0.11 μg/L was used as a conservative estimate of the expected toxicity in field exposures. An exposure profile based on measured field concentrations was used for laboratory pulse-exposure tests; fenthion was metered for 2 h to specified maximum concentrations, then flushed with seawater to cause a 6- to 8-h exposure, yielding a no-observed-effect concentration (NOEC) of 0.84 μg/L. In field tests, four ULV operations produced initial water concentrations < NOEC and no fenthion-induced shrimp mortality. However, the direct application's initial water concentrations ranged from 15 to 20 μg/L (> NOEC) and caused extensive mortality (90 to 100%) in the caged shrimp. Thus, field observations confirmed our hypothesis that if fenthion time-exposure concentrations were lower than the laboratory NOEC, then no mortality would occur in caged shrimp. Moreover, if initial concentrations in the field exceeded the laboratory NOEC, mortality would occur. These laboratory tests and field applications indicate that laboratory toxicity tests can predict the range of lethal and nonlethal acute field exposures to fenthion for pink shrimp when exposure regimes are similar.
The Sensitivity of Chronic Endpoints Used in Daphnia magna Straus Life-Cycle Tests
Authors: Gersich FM , Hopkins DL , Applegath SL , Mendoza CG , Milazzo DP
Published: December 2008

The sensitivity of three endpoints used to evaluate the chronic toxicity of boric acid, un-ionized ammonia, and triclopyr triethylamine salt (TEA salt) to Daphnia magna was examined. The endpoints examined during these studies were reproduction, growth, and survival. A 21-day static renewal toxicity test was conducted with Daphnia magna for all three test materials. The maximum acceptable toxicant concentrations (MATCs) derived from these studies were boric acid 6.4 < MATC < 13.6 mg B/L, unionized ammonia 0.42 < MATC < 0.87 mg NH3-N/L, and triclopyr TEA salt 80.7 < MATC < 149.0 mg/L. Reproduction was consistently the most sensitive endpoint in all three studies. An examination of the literature indicates that the utility and relative sensitivity of reproduction and survival as chronic endpoints have been questionable because of erratic adult survival and large amounts of reproductive variation. The data from this study show that use of well nourished and healthy test organisms reduces variability in both reproduction and survival and enhances the reliability of the daphnid chronic test.
Effects of Suspended Volcanic Ash and Thermal Shock on Susceptibility of Juvenile Salmonids to Disease
Authors: Poston TM , Neitzel DA , Abernethy CS , Carlile DW
Published: December 2008

Susceptibility of salmonids to the fish pathogen, Flexibacter columnaris, was used to assess sublethal stress following exposures to two environmental stressors, thermal shock, and suspended volcanic ash. Juvenile rainbow trout (Salmo gairdneri) were more susceptible to disease following exposure to 0.3- and 11.5-g/L suspended volcanic ash. The response was dose dependent. Exposure of juvenile chinook salmon (Oncorhynchus tshawytscha) to thermal shock did not result in increased susceptibility to disease. In several tests, thermally exposed fish were less susceptible to disease than control fish.
A Model for Estimating the Loading Rate of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin to the Great Lakes
Authors: Neely WB
Published: December 2008

Identifying trace contaminants in environmental samples is becoming a common occurrence. In order to complement this activity a method is needed to estimate the loading rate that is required to achieve the observed concentrations. By matching the loading rate with identified sources an assessment of their importance can be made. This study presents a framework by which loading rates can be estimated for the Great Lakes watershed. Using data and monitoring results for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) the model is illustrated, and a loading rate of 600 g/year was determined necessary to achieve the TCDD concentrations observed in Lake Huron fish.
Laboratory Electrochemical Test Methods
Authors: Siebert OW
Published: December 2008

Corrosion is an electrochemical reaction of a metal and its environment. The aim of this paper is to provide an understanding of some of the electrochemical processes that result in corrosion and to provide a reference compendium of the present state of the art laboratory test methods used to evaluate these reactions. An analysis of the mechanism of electrochemical corrosion needs to try to identify anodic and cathodic corrosion partial processes, establish the thermodynamic possibility of these processes (the tendency to corrode), and determine the kinetics of these processes (the rate of corrosion). A study of the thermodynamic relationship of the solution pH to the system potential indicates the corrosion product ions or precipitates with the lowest free energy. When corrosion occurs, the current that flows between individual small anodes and cathodes on the metal surface causes the electrode potential of the system to change. While this current cannot be measured, it can be evaluated indirectly on a metal specimen with an inert electrode and an external electrical circuit. Kinetic polarization is described as the extent of the change in potential of an electrode from its equilibrium potential caused by a net current flow to or from the electrode, galvanic or impressed. This review covers the several laboratory electrochemical test methods used to identify and evaluate these metallic corrosion reactions.
Current Versus Voltage Hysteresis: Effect on Electrometric Monitoring of Corrosion
Authors: Hirozawa ST
Published: December 2008

Potential-controlled polarization methods can cause large positive shifts of the breakdown potential because of induction effect. The latter gives rise to current hysteresis, which leads to large unpredictable charge densities, which leads to poor accuracy and precision in determining the protection potential Eprot. Galvanostaircase polarization (GSCP) prevents induction effect and current hysteresis; however, it is subject to voltage hysteresis, which could make the determination of Eprot difficult if not impossible. Fortunately, voltage hysteresis can be avoided easily by staying at low current levels and charge densities.

Hysteresis caused by slow electrode kinetics can give erroneous results in the cyclic potentiodynamic polarization resistance measurement. A potentiostaircase polarization method was used to eliminate hysteresis. A graphic averaging technique was developed to determine the polarization resistance of a system where the corrosion potential Ecorr and the corrosion rate were changing rapidly.
The Collapse of Defect Cascades to Dislocation Loops in Cu3Au
Authors: Black TJ , Jenkins ML , English CA , Kirk MA
Published: December 2008

We report a systematic experimental study of the conditions leading to vacancy dislocation loop formation at the sites of defect cascades produced by ion irradiations. Transmission electron microscopy (TEM) techniques and the ordered alloy Cu3Au were employed to measure the probability of dislocation loop formation as functions of irradiating ion mass (Ar+, Cu+, and Kr+), ion energy (50 and 100 keV), and sample irradiation temperature (30 and 300 K). Disordered zones in the ordered alloy were produced at every defect cascade site and imaged in dark-field superlattice reflections. Dislocation loops were imaged in fundamental reflections in the same sample areas to produce a very accurate measurement of the probability of the collapse of each cascade to a dislocation loop, within a large set (∼200) of defect cascades for each irradiation condition. The size distributions of dislocation loops and disordered zones were also measured for selected irradiation conditions. A central result was that defect cascades collapse to dislocation loops with significant probability (∼0.5) even at sample irradiation temperatures of 30 K. Other observations include an increasing collapse probability with increasing cascade energy density (increasing ion mass) and with increasing sample irradiation temperature. However no additional collapse was observed upon annealing from 30 to 300 K, and no increase in collapse probability was observed upon increasing the bombarding ion energy from 50 to 100 keV. Disordered zone sizes also increased with increasing ion mass and with increasing sample irradiation temperature (30 to 300 K).
Swelling of 316 Stainless Steel and D9 Cladding in FFTF
Authors: Makenas BJ
Published: December 2008

A data base of cladding swelling measurements from post-irradiation examinations of Fast Flux Test Facility (FFTF) 316 stainless steel clad fuel pins has been developed, which is now sufficiently large to compare to previously published cladding swelling data. This comparison of data was motivated by the observation, in the early cycles of FFTF operation, that design swelling correlations had to be adjusted to account for the observed length increases of driver assembly ducts. These original correlations had been developed from nonfueled EBR-II irradiation tests. The recent data indicate that FFTF and EBR-II cladding, from actual fuel pins with similar heats of steel, behave almost identically with respect to fast fluence. The FFTF data further suggest that, above ∼490°C, 316 stainless steel (SS) swells in a manner that is essentially independent of irradiation temperature. A comparison of immersion density measurements with the length increases for FFTF driver fuel pins has also shown the 316 SS cladding swelling behavior to be essentially isotropic. D9 cladding (a titanium modified variant of 316 SS) has also been irradiated in FFTF. The data base here is limited but is large enough to establish the superiority of D9 over 316 SS as an FFTF fuel pin cladding from a swelling point of view.
The Effect of Swelling in Inconel® 600 on the Performance of FFTF Reflector Assemblies
Authors: Makenas BJ , Trenchard RG , Hecht SL , McCarthy JM , Garner FA
Published: December 2008

The fast flux test facility (FFTF) is designed with nonfueled outer row assemblies, each of which consists of a stack of Inconel® 600 blocks penetrated by 316 stainless steel (SS) coolant tubes. These assemblies act as a radial neutron reflector and as a straight but flexible core boundary. During an FFTF refueling outage, it was observed that the degree of difficulty in withdrawing an outer row driver fuel assembly was a function of the peak fast fluence of neighboring reflector assemblies. It was subsequently determined through various postirradiation examinations that the reflector assemblies were both bowed and stiff. Measurements of the individual Inconel 600 blocks indicated that the blocks had distorted into a trapezoidal cross section because of differential swelling of Inconel 600 in a steep radial flux gradient. Immersion density results indicate greater irradiation induced volumetric swelling than any previously reported data or correlation for Inconel 600 at equivalent fast fluence. The Inconel 600 swelled approximately the same amount as the SA 316 SS reflector components. Transmission electron microscopy studies on the Inconel blocks and swelling measurements on related materials have been performed, and these data have been related to the performance of the reflector materials.
The Behavior of Solute Segregation and Void Formation in Fe-Cr-Ni and Fe-Cr-Mn Steels During Electron Irradiation
Authors: Takahashi H , Garner FA , Itoh H , Hu B , Ohnuki S
Published: December 2008

The relative swelling behavior of Fe-Cr-Mn and Fe-Cr-Ni alloys during electron irradiation is shown to be different from that observed in neutron irradiations. This difference appears to be a consequence of the different diffusion behavior of nickel and manganese in response to the operation of the inverse Kirkendall effect. The vacancy gradients driving the diffusion in these experiments are generated not only by the foil surfaces and the electron-generated radial displacement gradient but also by high angle grain boundaries deliberately centered in the middle of the electron beam. This procedure allows the relative diffusional characteristics of each element to be observed by energy-dispersive X-ray (EDX) measurements across the grain boundary. The influence of helium and minor solutes on swelling was also studied in these experiments and yielded no behavior atypical of that observed in neutron irradiation studies.
Transport of Helium to Grain Boundaries During Irradiation
Authors: Singh BN , Foreman AJE
Published: December 2008

The rate of accumulation of helium at grain boundaries is one of the important parameters determining the integrity and lifetime of the structural components of a fusion reactor. A diffusion calculation is made of the flux of helium to a grain boundary. The flux is found to depend on the gas production rate, the width of the cavity denuded zone, and the cavity sink strength in the grain interior. The calculated accumulation of helium is in good agreement with the measured gas content of grain boundaries in aluminum, PE 16, and 316 stainless steel. The flux of helium to grain boundaries increases with helium generation rate, but the increase is less than proportional to the generation rate. The loss of helium to grain boundaries during the nucleation of the bubbles within the grains has been estimated; no great loss is expected to occur. However, the loss would be considerably enhanced if any delay in bubble nucleation were to occur because of incubation effects. The role of material variables is found to be difficult to predict at present.
Irradiation-Suppressed Graphite and Cementite Precipitation in Fe-Ni-C and Ni-C Alloys
Authors: Best SE , Russell KC
Published: December 2008

The results of a theoretical and experimental study of the effect of ion irradiation on phase stability in austenitic Ni-C and Fe-Ni-C alloys are presented. Calculations modeling the precipitation of graphite or cementite from Ni-C or Fe-Ni-C alloys indicate that irradiation may induce precipitation of either phase in alloys that are thermally undersaturated in carbon. Graphite precipitation occurred readily in supersaturated thermally aged specimens. Although the theoretical calculations predict that rapid graphite nucleation may occur in a range of undersaturated and supersaturated alloys as a result of 4-MeV Ni2+ ion irradiation, transmission electron microscopy (TEM) studies reveal no indication of such precipitation. The irradiated alloys remained single phase even for one time-temperature cycle, which produced the beginning of graphite precipitation under purely thermal aging. We conclude that a trapping mechanism involving the redistribution of carbon from solid solution to radiation-induced dislocation loops, voids, and other traps, perhaps via a solute drag effect, operates in such a manner as to suppress the precipitation promoted by irradiation induced vacancies. The results of this study have important implications on the radiation stability of austenitic steels that lack strong carbide formers.
Amorphous Transformation of Laves Phase in Zircaloy and Austenitic Stainless Steel Upon Neutron Irradiation
Authors: Harris LL , Yang WJS
Published: December 2008

A variety of forms of irradiation have been observed to induce an amorphous phase: heavy ion, proton, and electron. More recently neutron irradiation has been observed to induce an amorphous transformation in Laves precipitates found in Zircaloy and austenitic steel. Up to this point, only conjectures have been made about the irradiation conditions necessary to achieve the amorphous transformation and about the characteristics of a material susceptible to the amorphous transformation. From these conjectures, a theory to explain the amorphous transformation is developed, and its application illustrated by simulation with a computer model. The amorphous transformation of the Zr(Fe, Cr)2 phase in Zircaloy induced by neutron irradiation is used as the example in the model. The theory proposes that during irradiation the free energy of the crystalline state increases beyond that of the amorphous state, and thus in efforts to minimize the free energy of the system the amorphous transformation occurs. The factors that contribute to this increase in free energy include the defect formation energies and the energies of mixing that arise as the lattice is disordered. The later contribution is found to be significant. It is this factor that makes the amorphous transformation possible at defect concentrations lower than required for transformation when defect generation alone is considered.
Solute Segregation and Microstructural Evolution in Ion-Irradiated Vanadium-Base Alloys
Authors: Loomis BA , Kestel BJ , Gerber SB
Published: December 2008

The microstructural evolution in V + 14.7 Cr, V + 2.5 Mo, V + 2.5 W, V + 8.0 Ni, V + 5.3 Ti, V + 14.7 Cr + 5.2 Ti, V + 9.6 Cr + 3.1 Fe + 0.7 Zr, and V + 3.2 Ti + 1.8 Si alloys (concentrations in atomic percent), and unalloyed V was determined from observations of specimens by transmission electron microscopy (TEM) following 4.0-MeV 51V++ ion irradiation at 900 to 970 K to 50 dpa. The radiation-induced segregation (RIS) of solutes in the ion-irradiated alloys was investigated by auger electron spectroscopy (AES), energy-dispersive X-ray spectroscopy (EDXS), and electron energy loss spectroscopy (EELS) analyses. The RIS of solutes and microstructural evolution in the irradiated alloys were correlated with the solute diffusivity and the relative chemical affinity of the substitutional solutes for oxygen.