bluuebunny/crossref_metadata_2025 huggingface dataset:
The Federal Effort to Control Community Noise
Authors: Elkins CL
Published: March 2009

Though hearing loss is the most clearly understood noise hazard, other serious threats to health are posed by noise, in particular those illnesses called diseases of stress. Important links have been researched between noise exposures and cardiovascular problems, especially, and growing evidence associates noise with psychological, social and economic effects. Although present knowledge of these effects is sufficient to support present regulatory efforts, indications of additional and serious effects from noise call for greater research investigation. In an effort to reduce these adverse effects, the Environmental Protection Agency (EPA) has developed a series of strategies to control noise from major sources. Using urban traffic and freeway noise as examples, the contribution of these sources to public exposure has been analyzed and emission levels set for interstate motor carriers, trucks, buses and motorcycles, with other motor vehicle sources to be regulated in the future. To hold surface transportation noise levels at no higher than those of today will require substantial further action. Significant advances in available technology must be made to lower emission levels. EPA currently conducts and coordinates Federal research activities, but the total Federal research budget has declined drastically since 1973 when the Noise Control Act was enacted. This reduction in funds is a constraining factor on noise standard setting. There are 15 million people impacted by aircraft noise, but the Noise Control Act provides EPA with no effective way of reducing aircraft noise emissions. Another constraint in promulgating effective regulations is the lack of adequate measurement methodologies for many products. The greatest future needs are for products subject to labeling, particularly household and consumer products. In order to deal effectively with these problems, strong state and local noise control programs are essential, without which the Federal efforts would not be fully effective. The states can play major roles in promoting local ordinances, and enforcing standards. Because national ambient standards have not been mandated by Congress, the noise program includes a unique set of assistance programs to states and localities. Among these are model ordinances and model product specifications, demonstration projects, training of elected officials, noise control officials and police officers, using trained volunteers to deliver technical assistance and senior citizens to implement certain portions of the local effort.
Physiological Techniques for Assessing the Impact of Oil on Seabirds
Authors: Peakall DB , Miller DS , Kinter WB
Published: March 2009

Physiological changes seen when oil is ingested by seabirds are considered as a tool to assess the role of oil in seabird “wrecks.” The effects of oil include an increase of the percent weight of adrenals and nasal glands, decrease in uptake of nutrients in the intestine, and a transient rise in plasma sodium and cortico-sterone levels.
Acute Toxicant Identification in Whole Bodies and Baits Without Chemical Analysis
Authors: Johns BE , Thompson RD
Published: March 2009

We propose a system utilizing small color-coded plastic particles to identify acute toxicants in digestive tracts and baits without chemical analysis. Test results show that the coded particle is suitable for incorporation into various baits, does not cause bait aversion, and is readily recovered from digestive tracts and fecal samples without loss of code integrity. Toxicant identification in coyotes poisoned secondarily after eating rodents is demonstrated. The proposed concept of toxicant identification is feasible. We suggest that the identification system be included in the manufacture of toxic baits.
Which Populations of Aquatic Bacteria Should We Enumerate?
Authors: Costerton JW , Geesey GG
Published: March 2009

Bacteria in aquatic systems comprise at least four distinct populations. The planktonic population floates in the water column with the particle-associated population, while the epilithic and epiphytic populations are attached to submerged surfaces, and the sediment population occupies the water-filled spaces of the sediment. Samples taken from the water column include the planktonic and particle-associated bacteria, and core samples include the sediment population, but special techniques are required to sample the epilithic and epiphytic organisms. In all bacterial populations, except the planktonic, the natural adhesion of the cells to surfaces and to each other produces adherent microcolonies whose cohesion presents special problems in bacterial enumeration.

Since we have described freshwater systems in which epilithic bacterial populations are numerically dominant, and since large sediment populations are found in most aquatic systems, it is imperative that bacterial enumeration studies recognize each of these distinct populations. The authors examine the methods available for the enumeration of the bacteria in each distinct population and suggest a holistic approach to bacterial enumeration that can be applied to any aquatic system.
Direct Epifluorescence Enumeration of Native Aquatic Bacteria: Uses, Limitations, and Comparative Accuracy
Authors: Daley RJ
Published: March 2009

The suitability and comparative accuracy of the acridine-orange epifluorescence direct-count (AODC) technique for determining the numbers, biomass, and metabolic state of aquatic bacteria are reviewed, The AODA method has been indirectly verified as the best available procedure for estimating the total numbers of native aquatic bacteria. It is quantitative, precise, and suitable for use with both pelagic and epibenthic bacteria in all freshwater and marine environments. The development of a standard method should be possible by making only a few technical improvements. However, AODC numbers cannot be converted directly to total carbon biomass because of natural variations in bacterial cell sizes. It is possible that better biomass estimates can be obtained by using combined AODC measurements of cell numbers and cell volumes, but the accuracy of this approach is still to be determined. The alternative, indirect estimation of lipopolysaccharide (LPS), appears, from limited tests, to be accurate for planktonic marine bacteria; however, interference from blue-green algal LPS may restrict its use in fresh waters and sediments.

The distribution of dead, moribund, viable, and growing bacteria within the total population visualized by epifluorescence is unknown. However, recent indirect evidence suggests that most, if not all, native bacteria are viable, but that many are metabolically dormant. Neither the AODC technique nor any of the “living” biomass techniques (plate, membrane, or liquid growth techniques, ATP assays, autoradiography) now used can distinguish the functional states of native bacteria. Autoradiography combined with epifluorescence has the best potential for such measurement, but further assessment is necessary.

The usefulness of the AODC method for descriptive surveys, correlative studies, impact assessment activities, and experimental studies of bacterial dynamics is summarized. Epifluorescence enumeration, in conjunction with activity measurements and filter fractionation procedures, holds considerable promise for examining the productivity and nutrient uptake dynamics of native aquatic bacteria.
Enumeration of Specific Populations by the Most-Probable-Number (MPN) Method
Authors: Colwell RR
Published: March 2009

The most-probable-number (MPN) method of bacteria enumeration dates back to the earliest days of bacteriology. Despite drawbacks of the method, it offers a relatively simple and useful means of estimating microbial populations, especially for determining the physiological potential of microbial biomass.
Bacterial Biomass Determinations in a Silt-Laden River: Comparison of Direct Count Epifluorescence Microscopy and Extractable Adenosine Triphosphate Techniques
Authors: Geesey GG , Costerton JW
Published: March 2009

Bacterial biomass determinations in the Athabasca River were complicated by the presence of large quantities of suspended silt in the flowing water. Differences in the size of free-living and particle-associated bacteria had to be considered in cell-volume-based biomass estimations. While the presence of particles did not present major difficulties for the detection of bacteria by epifluorescence microscopy, problems were encountered during biomass estimations based on extractable ATP. Corrections had to be made for particle and chemical quenching in the ATP assay. After appropriate adjustments had been made, the ATP-based biomass values indicated that a large fraction of the cells present in the water were dead. Incomplete extraction may have contributed to the apparent high numbers of dead bacteria.
Heterotrophic Activity Measured with Radiolabelled Organic Substrates
Authors: Wright RT , Burnison BK
Published: March 2009

Microbial ecologists have employed a variety of methods using radiolabelled organic substrates to measure the activity of heterotrophic bacteria in natural waters. The relationships between natural and added substrate concentrations and between subtrate concentration and uptake rate provide important criteria for evaluating the different methods. The methods presented and discussed are: (1) direct calculation approach, (2) tracer approach, (3) kinetic approaches (including transport kinetics and diffusion kinetics), and (4) an alternative kinetic approach. The first three differ in the data yielded, and are recommended for specific applications where heterotrophic activity is to be measured. The fourth method is not recommended, as it is shown to be based on faulty assumptions. The authors conclude that the available methods are best viewed as tools for investigative research. Moves towards standardization should be made cautiously.
Heterotrophic Activity Determination by Substrate Disappearance
Authors: Westlake DWS
Published: March 2009

The physical, chemical, and microbiological techniques available for monitoring environmental heterotrophic microbial responses to substrate additions are discussed. The advantages of chemical assays in monitoring changes in mixed substrates or substrates added at very low concentrations are stressed. In order to understand the responses of the indigenous microbial flora, however, both chemical and microbiological changes have to be determined.
Determination of the Heterotrophic Activity of Epilithic Microbial Populations
Authors: Ladd TI , Costerton JW , Geesey GG
Published: March 2009

The heterotrophic activity of planktonic and the numerically dominant epilithic bacterial populations in mountain streams was measured using radioactive labelled 14C-glutamic acid. The activities of these populations were compared, using a specific activity index based on the maximum number of cells per litre or square centimetre, determined by epifluorescence direct counting of the samples. Dispersed and in situ sessile bacterial populations from colonized stone squares were as much as 26 and eight times, respectively, more active per cell than the free-floating planktonic populations. The increased activity per cell of the disturbed epilithic population suggests that there is greater substrate accessibility for dispersed cells and indicates that at low substrate concentrations the polysaccharide matrix encasing the in situ population may be limiting the substrate diffusion. The uptake of glutamic acid, measured by the heterotrophic potential technique, clearly demonstrated that the epilithic population of the flowing stream actively contributed to the removal of organic molecules from the surrounding waters.
Holographic Techniques for Defect Detection in Composite Materials
Authors: Maddux GE , Sendeckyj GP
Published: March 2009

The results of an experimental study of holographic interferometry and tetrabromoethane (TBE)-enhanced X-ray photography for damage detection in composite materials are presented. The results show that holographic interferometry using thermal loading can accurately track delamination growth, but cannot find subsurface matrix cracks. It can also provide information on the through-the-thickness distribution of delaminations. TBE-enhanced X-ray photography can find matrix cracks, delaminations, and fiver bundle fractures, but gives no information on the through-the-thickness distribution of the damage.
Effects of Material Inhomogeneities on Ultrasonic Measurements: The Problem and a Solution
Authors: Heyman JS , Cantrell JH
Published: March 2009

Most ultrasonic measurements of materials involve the generation of an acoustic wave and the propagation of that wave from a transducer through a coupling medium to a specimen under test. After interacting with the specimen, the wave propagates through the coupling medium to a receiving transducer and is converted to an electrical signal. The information presented to the observer by the electrical signal depends on each element of the system.

In this paper, we examine the role that the receiving transducer plays in ultrasonic measurements. The phase-sensitive nature of conventional receiving transducers has, for the most part, been neglected in nondestructive evaluations. This is shown to lead to significant data misinterpretation.

A new acoustoelectric transducer (AET) has been developed which is phase insensitive. Comparative data obtained with both conventional and AET transducers are presented and discussed. The AET is shown to produce more accurate measurements for the cases investigated.
Neutron Radiographic Nondestructive Inspection for Bonded Composite Structures
Authors: Dance WE , Middlebrook JB
Published: March 2009

Neutron radiography was found to be effective as a nondestructive inspection technique for detection of bondline voids/defects in a variety of composite structures. Radiographic data are presented in this paper from typical structures for which the neutron radiographic inspection technique offers advantages over more convetional inspection techniques. Complex composite joints such as box beam members, for example, are difficult to inspect by ultrasonic techniques, and the X-ray attenuation coefficients of the different materials in composite/metal combinations differ in such a manner as to yield very little nondestructive inspection (NDI) information regarding the integrity of the bond. Accurate bondline defect information was achieved in such structures utilizing a transportable californium-252(252Cf) neutron radiography system containing approximately 2 mg of the 252Cf isotope. Through techniques developed at Vought Corp. Advanced Technology Center, resolution of simulated bondline voids as small as 0.127 mm (0.005 in.) diameter in laminated graphite/epoxy specimens was achieved. It is expected that continuing improvements in imaging techniques, and in mobility of neutron sources for radiography, will spawn wide usage of the neutron technique for nondestructive inspection of complex wing joints, control surfaces, and other airframe structures.
Liquid Crystals for Flaw Detection in Composites
Authors: Charles JA
Published: March 2009

Liquid crystals have been investigated as an inexpensive nondestructive testing (NDT) technique for composite materials. By imaging the surface temperature distribution on both cyclically loaded and unloaded materials, subsurface flaws are found to be detectable. For specimens under load, likely damage locations and subsequent damage development can be determined. Cut fibers, inclusions, and geometric discontinuities served as flaws. Fiber glass/epoxy and graphite/epoxy composites were tested. It was found that liquid crystals can be used as an alternative to other NDT methods in many cases.
Fracture Surface Characterization of Commercial Graphite/Epoxy Systems
Authors: Miller AG , Wingert AL
Published: March 2009

The fracture surface morphologies of graphite/epoxy composite materials have been studied to determine the influences of load history, material configuration, temperature, moisture and matrix system type. Three commercially available systems with unidirectional tapes loaded in tension and fabrics tested in shear were chosen for analysis. Elevated temperature, moisture exposure, or both increase the amount of fiber pullout in the unidirectional tapes. Only in one case was the pullout fracture mode changed from a cohesive to an adhesive type of fracture process. The shear-loaded fabrics displayed either a tensile flexure fracture or an apparent shear fracture mode. The latter mode was believed to be actually a tensile rupture mode due to a resolution of shear stresses into tensile stresses. A transition temperature was defined to denote the temperature at which the fracture mode changed from tensile flexure to apparent shear. Significant differences in fracture surface morphology were observed among the three commercial graphite/epoxy systems.
Characterization of Constraint Effects on Flaw Growth
Authors: Yeung PC , Stinchcomb WW , Reifsnider KL
Published: March 2009

Experimental results have been presented for the case of a flawed unidirectional lamina constrained by off-axis unflawed plies under static and fatigue loading. Flaw growth in the interior of the laminate, around the embedded flaw, was followed by nondestructive testing methods including video-thermographs and ultrasonic C-scan schemes. Two aspects of the results were distinctive. There was an effort of lamination on damage development which was independent of the presence of the notch, and effects which were directly related to the influence of the notch on the local situation. The results are compared with sectioning studies, surface replication, and stiffness change measurements.
Unisteel Testing of Aircraft Engine Bearing Steels
Authors: Day KL
Published: March 2009

A modified form of “Unisteel” testing was adopted over 15 years ago with the basic objective of screening aircraft bearing materials and their heat treatment prior to, or as an alternative to, full-scale testing. The aim was to obtain a statistically significant quantity of data relatively quickly and relatively cheaply in comparison with full-scale rig or engine testing. The rig and its operating techniques are described with their known virtues and shortcomings as well as a description of the typical results analysis technique used. Typical comparative results obtained from a range of through-hardened materials are included to illustrate the variations obtained from different melting sources, heat treatments, and so on.
Experience of Element and Full-Bearing Testing of Materials over Several Years
Authors: Johnston GB , Andersson T , Amerongen Ev , Voskamp A
Published: March 2009

A review is made of several years' experience in determining quantitatively the influence of material and production processes on the fatigue performance of rolling element bearings. This experience covers bearing testing and two different “element” test methods—the radial ball bearing with cylindrical inner ring and the thrust ball bearing with flat washer methods.

So far, it has been difficult to correlate the results from those element tests with results obtained from full-bearing tests. This is due to the special features of the concentrated point contacts between the balls and nonconforming surfaces used in the element methods. These features are an apparently random groove formation and a material transformation and failure mode different from those of normal bearings.
Use of Accelerated Tests to Establish the Lubricant-Steel Interaction on Bearing Fatigue Life
Authors: Eastaugh PR
Published: March 2009

For several years the Royal Navy has used hydraulic fluids which differ significantly from the lubricants used by bearing manufacturers when establishing load to life characteristics. The performance of relevant fluids has been assessed in conjunction with standard EN31 (AISI 52100) steel test specimens using two standard test machines (the rolling four-ball and Unisteel) and a rolling contact fatigue rig designed and built in the author's department.

In addition, a high speed rolling four-ball machine is being commissioned. The test results show that wide variations in performance occur with different lubricant-material combinations, and it is necessary to run tests at several different levels of severity in order to predict service performance reliably. The standard rolling four-ball test did not give good correlation with other test data, and a metallurgical investigation of some failed specimens suggests that an abnormal failure mechanism could be operating.
Rolling Contact Fatigue Mechanisms—Accelerated Testing Versus Field Performance
Authors: Zwirlein O , Schlicht H
Published: March 2009

Cycling tests in the laboratory serve to assess the qualitative and quantitative influences of specific parameters on the service life of rolling bearings by systematically varying these parameters in the tests. The applicability of the test results to the field is a precondition for the optimization of material and design.

Material stress is analyzed and described by various alterations in the material caused by cyclic stressing. The conditions under which cyclic stressing generates structural alterations are demonstrated. This paper refers especially to the influence of different contact pressures and residual stresses on material stress and the failure mechanism at cyclic stressing.
KIc and JIc of Westerly Granite—Effects of Thickness and In-Plane Dimensions
Authors: Schmidt RA , Lutz TJ
Published: March 2009

An investigation is described in which tensile properties, fracture toughness, and critical J-integral are measured for Westerly granite, a rock that is used widely in rock mechanics studies. This was primarily a parameter sensitivity study in which the effects of specimen dimensions and testing techniques were assessed. It is hoped that this study will aid in establishing tentative standards and guidelines for fracture toughness testing of rock as well as indicate the feasibility of using a J-integral fracture criterion for this material.

ASTM standard specimen configurations of the compact and bend types were tested with compact specimens ranging in width from W = 25.4 mm to W = 406.4 mm (0.5T to 8T) and with thickness ranging from 13 to 100 mm. A series of 4T compact specimens were tested to assess the effects of thickness and fatigue precracking.

Techniques are described that enable several values of KIc, a complete J versus crack growth curve, and a JIc value to be obtained from each sample. Direct-pull tension tests on shaped specimens of Westerly granite are described which indicate a high degree of nonlinear, inelastic behavior. This fact raises questions about the use of linear elastic fracture mechanics, LEFM, but the JIc data presented appear to validate the KIc measurements.
Further Evidence of Zircaloy Corrosion in Fuel Elements Irradiated in a Steam Generating Heavy Water Reactor
Authors: Sumerling R , Garlick A , Stuttard A , Hartog JM , Trowse FW , Sims P
Published: March 2009

An earlier paper (Trowse et al, ASTM STP 633) described the nodular corrosion of Zircaloy and other zirconium alloys in a steam generating heavy water reactor (SGHWR) and related environments. The observations have now been extended to more highly irradiated elements up to the design burn-up of 20 MWD/kgU mean. Maximum observed local oxide thicknesses were less than the earlier predictions of 200 μm for SGHWR cladding at the design burn-up and are acceptable from fuel performance considerations.

Most of the data presented relates to Zircaloy-2 in the stress-relieved condition, but results from elements with recrystallized cladding show that oxidation resistance can be improved by this treatment. In particular, the oxide nodules are much finer in the recrystallized alloy, leading to a generally smaller coverage of nodular oxide.

The maximum depth of oxidation is correlated to fast neutron dose and is apparently little affected by coolant mass flow-rate or steam quality.

Previous work had shown evidence for oxidation enhancement of Zircaloy at support grid positions by galvanic coupling to stainless steel and also by localized coolant flow disturbance. In order to determine the relative importance of these two factors, an experimental element fitted with alternate stainless steel and Zircaloy grids of similar geometry was irradiated in SGHWR. The results confirmed that most of the oxidation enhancement is due to the galvanic coupling but that significant flow effects at grids were also present in the higher flow, higher steam quality region of the element down-stream of the peak flux position.
A Survey of the Chemical Environments for Activity in the Embrittlement of Zircaloy-2
Authors: Grubb WT , Morgan MH
Published: March 2009

Thirty-five chemical elements and some of their compounds were tested for activity in the embrittlement of Zircaloy-2 at 573°K using constant extension rate tension tests. Besides iodine, which embrittles by stress corrosion cracking (SCC), five metals caused liquid metal embrittlement when dissolved in cesium. These were cadmium, zinc, yttrium, calcium, and strontium. The effect of cadmium was by far the most severe. Selenium and tellurium did not embrittle Zircaloy-2 by SCC. Of the embrittling metals, only cadmium is considered a likely contributor to the PCI (pellet-clad interaction) failure mechanism. The reasons for this conclusion are discussed.
Irradiation Growth in Cold-Worked Zircaloy-2
Authors: Murgatroyd RA , Rogerson A
Published: March 2009

Irradiation growth has been studied in 25 percent cold-worked Zircaloy-2 at temperatures of 353 and 553 K. At 353 K, a rapid increase in growth strain occurs at doses less than 1024 n/m2 (neutrons per square metre) followed by a linear growth rate at higher dose. At 553 K, significantly lower strains are attained upon irradiation to 1024 n/m2, but the subsequent growth rate is higher. Thus, at a dose of about 1025 n/m2, the growth strains achieved at the two temperatures are similar. The data have been fitted to both linear and power law relationships, and comparisons are made with data reported for both annealed and cold-worked Zircaloy-2.

Two important effects of temperature have been established. First, at doses less than 5 × 1024 n/m2, growth in cold-worked Zircaloy-2 at 553 K is significantly less than at 353 K. Second, at 353 K, growth in 25 percent cold worked Zircaloy-2 is linearly dependent on dose above a dose of 1 × 1024 n/m2; this contrasts with the growth saturation observed in annealed material irradiated at the same temperature.

The observed growth behavior is interpreted in terms of a growth model consisting of two temperature-dependent components; one due to the nucleation and growth of small defect clusters and loops during the early stages of irradiation, and a second due to the preferential absorption of interstitials at the existing dislocation structure.
Iodine-Induced Stress Corrosion Cracking of Fixed Deflection Stressed Slotted Rings of Zircaloy Fuel Cladding
Authors: Sejnoha R , Wood JC
Published: March 2009

Stress corrosion cracking of Zircaloy fuel cladding by fission products is thought to be an important mechanism influencing power ramping defects of water-reactor fuels. We have used the fixed-deflection stressed slotted-ring technique to demonstrate the following:

1. Hydride layers plated electrolytically onto the surfaces of Zircaloy rings, cut from a batch of cold-drawn material, either increased the time to failure or prevented cracking in iodine vapor at 573 ± 3 K, giving rise instead to a generalized pitting attack. The presence of hydride changed the cracking mode from mainly transgranular cleavage to mainly integranular cracking.

2. In two batches of tube-reduced Zircaloy tubing, one annealed and one as-received, cracking could not be induced in iodine vapor at 573 ± 3 K even with axial scratches on the inside surface. However sharp precracks did propagate readily when their depths and the applied stresses were great enough.

3. One batch that had remained intact when tested in the as-received condition cracked readily in iodine vapor at 573 ± 3 K after stress relief. In the stress-relieved tubing, prescratching did not affect failure times, and cracks nucleated away from the notches. This contrasted with tests in methanol-iodine at room temperature, where notches shortened failure times substantially, the cracks nucleating at the notches.

The results show both the sensitivity and limitations of the stressed slotted-ring method in determining the responses of tubing to stress corrosion cracking. They are interpreted in terms of stress relaxation behavior, both on a microscopic scale for hydrogen-induced stress-relief and on a macroscopic scale for stress-time characteristics. Our analysis also takes account of nonuniform plastic deformation during loading and residual stress buildup on unloading. It is shown that when stress corrosion cracking occurred, it was in conditions where stress relaxation was sufficiently slow that the applied stress exceeded the critical stress for stress corrosion cracking, which itself is a function of exposure time and also the metallurgical condition of the tubing.
Hydride Cracks as Initiators for Stress Corrosion Cracking of Zircaloys
Authors: Cox B
Published: March 2009

Examination of specimens from one batch of Zircaloy fuel cladding that had been partially cracked in iodine vapor at 300°C has shown small fractured hydrides at the initiation sites of the transgranular stress corrosion cracking (SCC) process. Investigation showed that small radial hydrides were present at the inside surface of the original tubing and that these fractured at the start of the SCC test. In other environments, (for example, a solution of iodine in methanol), where extensive intergranular corrosion occurs at the initiation site, these cracked hydrides were ignored as initiators for the SCC process. A survey of other batches of tubing found a number of batches also showing radial hydrides at the inside. The occurrence of these hydrides did not correlate well with susceptibility to SCC in iodine vapor at 300°C. It has proved impossible to render a resistant batch of tubing susceptible to SCC by deliberately precipitating radial hydrides at the inside surface. However, by “decorating” cracked hydrides with thick (2–5-μm) oxide films, it has been found that a few radial hydrides crack at the start of the SCC test in those batches of tubing susceptible to SCC in a split-ring test, but no hydrides crack in resistant batches of tubing. Thus, the cracking of a radial hydride at the inside surface is an important initiation step in batches of tubing containing such hydrides. There must also be other initiation processes available in order to account for failures in susceptible batches of tubing that do not contain radial hydrides at the inside surface.
A Comparison of Experimental Cladding Microstructure Resulting from Uranium Oxide-Zircaloy Interaction with a Diffusional Assessment of Oxygen Transport for a Coupled Two-Media Problem
Authors: Cronenberg AW , El-Genk MS
Published: March 2009

During high-temperature transients on Zircaloy-clad nuclear fuel rods, both external and internal cladding oxidation have been observed. The result of such oxidation is to embrittle the cladding, making it susceptible to brittle fracture. External oxidation of Zircaloy in a steam environment is relatively well understood, while the internal processes have received little attention. This paper examines the internal oxidation process that occurs as a result of oxygen transport from the uranium oxide fuel pellets to the Zircaloy cladding. An oxygen diffusion model has been derived that solves a coupled two-medium problem with a moving boundary in Zircaloy due to the α-β phase change. Analytical results for the time and temperature dependence of such Zircaloy oxidation were found to compare favorably with both in- and out-of-pile experimental data, indicating that the underlying oxidation process is diffusion controlled.
Embrittlement of Zircaloy-Clad Fuel Rods Irradiated Under Film Boiling Conditions
Authors: Hobbins RR , Seiffert SL , Ploger SA , Mehner AS , MacDonald PE
Published: March 2009

Pressurized water reactor type fuel rods are being irradiated under postulated accident conditions in the Power Burst Facility at the Idaho National Engineering Laboratory as part of the Thermal Fuels Behavior Program. In these tests, film boiling was achieved by establishing a mismatch reactor power and coolant flow, while maintaining the coolant pressure at 15 MPa.

Cladding embrittlement resulting from film boiling operation of intact fuel rods was found to be consistent with previously established embrittlement criteria based on oxygen content in β-Zircaloy, but not with previously established criteria based on either fractional thickness of transformed β or equivalent cladding reacted.

Rods that were operated with breached cladding were embrittled to a greater degree than intact fuel rods under similar oxidizing conditions. This embrittlement appears to be associated with rim α and acicular α precipitation within the transformed β field as well as with enhanced hydrogen absorption.
Aquatic Toxicology: Anarchy or Democracy?
Authors: Macek KJ
Published: March 2009

The current state of the field of aquatic toxicology is assessed in terms of its development as a science. The author suggests the recent growth in the field has been “quantitative” but not “qualitative,” that is, there has been an increase in data rather than an increase in knowledge. The reason for this development is the influence that regulatory restrictions have on the scope of activities and methods used in conducting aquatic toxicity studies. A definite need exists for development of a mechanism which would provide for significant research in the field to be conducted outside of the regulatory framework.
Relationship Between Response Parameter Hierarchies, Statistical Procedures, and Biological Judgment in the NOEL Determination
Authors: Javitz HS
Published: March 2009

The U. S. Environmental Protection Agency recommended protocol for the fathead minnow life-cycle test specifies the measurement of numerous basic, but fragmentary, response parameters. Various researchers have recognized the need for combining those basic responses into global responses, which are more indicative of species survivability and ecological impact. One method of satisfying this need is to construct a hierarchy of responses. We illustrate a hierarchy of responses, currently being used in SRI experiments on munitions wastewaters, which consists of 31 basic responses (including new cumulative survivability responses) and 4 global responses.

The use of a hierarchy of responses including global responses necessitates the development of statistical tests for these responses and highlights the problems associated with potentially large overall significance levels. The use of Dunnett's test for assessing the statistical significance of the global responses is recommended along with the subdivision of aquaria to provide adequate degrees of freedom. In addition, we discuss methods for accurately estimating and reducing the generally unacceptably large overall significance level associated with the policy of declaring a concentration to be above the no-observed-effect level (NOEL) whenever any response is statistically significant.

The importance of incorporating biological judgment and expertise into the NOEL decision is gaining recognition, and a schema for this incorporation is presented. Methods for modifying the statistical tests to detect only biologically important response differences and statistical and graphical techniques for assisting the application of biological judgment are examined. The application of biological judgment in the NOEL decision is found to lower the overall significance level, and a method (postrandomization) for estimating that reduction is presented.
Considerations in the Design and Analysis of Chronic Aquatic Tests of Toxicity
Authors: Feder PI , Collins WJ
Published: March 2009

Some considerations in the planning of toxicity tests and in the reporting of results are discussed. The need for using standardized stocks of fish and standardized data recording and data reporting procedures is argued. Standardized sheets for reporting hatchability data are presented as an example of a number of standardized data reporting sheets developed by the authors.

We consider aspects of the statistical analysis of data arising from aquatic toxicity tests. The discussion emphasizes analyses and data displays for the interpretation of qualitative mortality and abnormality data, but the ideas pertain also to other types of data.

The techniques discussed include preliminary graphical displays, tests for homogeneity among tanks within treatment groups, adjustments to account for tank-to-tank heterogeneity within groups, outlier detection procedures, overall tests for treatment effects, multiple comparisons and pairwise confidence intervals of treatment groups with the control group, and dose-response curve fitting with associated estimates of “safe concentrations.”
Development of a Sperm Cell Toxicity Test for Marine Waters
Authors: Dinnel PA , Stober QJ , Crumley SC , Nakatani RE
Published: March 2009

Preliminary methods for conducting a quick and sensitive sperm cell toxicity test for marine waters have been developed. This paper presents a simple static test in which sea urchin or sand dollar sperm cells are exposed to test or control solutions for short periods of time (typically 15 to 60 min). Eggs are added to the test containers after the sperm exposure period has ended, and a standard time is allowed for fertilization to take place before the eggs are fixed with formalin. Samples are then tabulated for fertilization success by noting the presence or absence of the fertilization membrane. The results are analyzed by standard statistical methods to yield a time-dependent median effective concentration (EC50) (that is, the concentration of the test material that is effective in reducing fertilization success by 50 percent) after a specified period of exposure.

Sperm cell toxicity tests with two reference toxicants (silver nitrate and the pesticide endosulfan) showed that toxic responses were directly related to sperm exposure time. The 60-min EC50s and 95 percent fiducial limits for green sea urchin (Strongylocentrotus droebachiensis) sperm were 76 (57 to 103) and 168 (99 to 285) µg/litre for silver and endosulfan, respectively. The 60-min EC50s for sand dollar (Dendraster excentricus) sperm were 45 (34 to 61) and 147 (123 to 175) µg/litre for silver and endosulfan, respectively. Matrix bioassays using temperature, salinity, and toxicant concentration as variables showed that the toxic response to both silver and endosulfan generally increased with increasing temperature and decreasing salinity. One test series of silver and endosulfan in combination showed that toxicity was additive. Comparative sea urchin and sand dollar embryo tests (72 to 96 h) showed embryo sensitivity to be similar to sperm sensitivities with levels of effect (retardation of development) of 50 and 25 µg/litre, respectively, for silver and 253 and 158 µg/litre for endosulfan.

Additional development and refinement of this sperm cell toxicity test should yield a rapid and sensitive procedure for screening large numbers of toxicants in marine waters, aid in the prediction of ecological effects, and provide an additional tool for the biomonitoring of receiving water quality.
Effect of Linear Alkylbenzene Sulfonate on the Structure and Function of Microbial Communities in Model Ecosystems
Authors: Larson RJ , Maki AW
Published: March 2009

The effect of linear alkylbenzene sulfonate (LAS) on the structure and function of microbial communities was studied in a flow-through model ecosystem containing several trophic levels. The LAS was supplied to 19-litre glass aquaria at 0.5 and 5.0 mg/litre in either well water (Phase I) or sewage effluent (Phase II). The structure of microbial populations was estimated from measurements of total viable biomass; function assays consisted of measuring rates of glucose or LAS degradation, or both. Assays of microbial function were also carried out in waters from two rivers.

The results of Phase I studies indicated that LAS had no effect on microbial structure at either dose level. Microbial function was also unaffected at the low-dose level, although both glucose and LAS degradation were inhibited at the high-dose level. By contrast, 5 mg/litre LAS had no effect on microbial function in river water exposed to sewage effluent, as measured by the rate of LAS degradation. Similarly, there was no decrease in function of the microbial populations exposed to ∼5 mg/litre LAS in the Phase II model ecosystem. It was further noted that the overall kinetics of LAS degradation in Phase II model ecosystems were essentially identical to those in two river waters. From Phase I and Phase II studies the following were concluded: 1. Function measurements were preferable to structure measurements in characterizing mixed microbial communities. 2. The function of microbial communities in relatively simple model ecosystems closely approximates that of natural populations in surface waters.
Comparison of a Luminescent Bacterial Test with Other Bioassays for Determining Toxicity of Pure Compounds and Complex Effluents
Authors: Qureshi AA , Flood KW , Thompson SR , Janhurst SM , Inniss CS , Rokosh DA
Published: March 2009

A variety of chemical compounds and complex effluents were evaluated for toxicity using a luminescent bacterial test, and the results were compared with those of the rainbow trout, Spirillum, and Daphnia static bioassays. Direct correlations of the results were difficult as these assays utilize organisms of different levels of biological complexity. The data, however, demonstrated that in the majority of cases the luminescent bacterial test sensitivity was comparable with that of the rainbow trout, Spirillum, and Daphnia bioassays; particularly for organic compounds and complex effluents. Furthermore, this test appears to be relatively inexpensive, rapid, and simple, requires small sample volumes, and generally provides good reproducibility.

While the luminescent bacterial test has potential as a valuable tool for short-term toxicity testing of effluents and specialty chemicals, it may be a poor indicator of toxicity for wastewaters containing certain specific compounds (such as ammonia or cyanide). Moreover, the test alone cannot substitute for acute or sublethal hazard assessment. It is therefore recommended that the luminescent bacterial test be used in a battery of screening tests or to supplement other well-established toxicity bioassays.
Investigations in Aquatic Behavioral Toxicology Using a Computerized Video Quantification System
Authors: Miller DC , Lang WH , Greaves JOB , Wilson RS
Published: March 2009

The effects of pollutants on the behavior of aquatic organisms are being investigated for the purpose of developing behavioral tests applicable to routine toxicological assays. Although behavioral responses are known to be valuable in detecting the biological effects of certain types of pollutants, behavior has rarely been used in routine assays because of the difficulties in making observations and in quantifying behavioral change. We have reduced these problems appreciably through the use of a closed-circuit television system and the quantification of the behavioral record by computer. The behavioral analysis system used is an on-line interactive system capable of analyzing linear and angular parameters of motion for groups of organisms recorded simultaneously. It may be adapted to study material ranging in size from bacteria to fishes.

The findings are presented on the effects of copper and cadmium on selected behaviors of Stage II and III nauplii of the barnacle Balanus improvisus. Both metals alter nondirected (spontaneous) swimming activity in a dose-related biphasic manner, with hyperactivity usually occurring initially, followed by suppressed activity. Copper also alters phototaxis in these nauplii, thus reducing the percentage of individuals displaying positive phototaxis and, at higher concentrations (72 and 138 ppb), causing a shift to negative phototaxis in some individuals. The sensitivity of these behavioral responses is compared with two developmental parameters monitored during the same assay.

Behavioral tests may provide important information for hazard evaluation. Each behavioral alteration observed here may have adverse ecological implications. In addition, tests of nondirected activity and directed responses of aquatic organisms may also be valuable as routine screening tools to identify chemicals toxic to neural or motor systems.
Development and Testing of a Laboratory Model Ecosystem for Use in Evaluating Biological Effects and Chemical Fate of Pollutants
Authors: Bailey HC
Published: March 2009

An aquatic model ecosystem for use in assessing biological effects of polutants and their chemical fate was developed. The basic test units were housed in 3-litre battery jars and used sand as the substrate and modified algal assay medium as the aqueous component. The biological components included a benthic oligochaete, Lumbriculus variegatus; a zooplankter, Daphnia magna; and the alga Selenastrum capricornutum. A small air pump in the center of each jar was maintained at a low bubbling rate to keep the algae in suspension. Two chemicals, 2,4,6-trinitrotoluene (TNT) and 2,4-dinitrotoluene (DNT), were tested separately using a 21-day exposure period. Each chemical was tested in duplicate, and agreement between the replicates was good. The direct toxic effects of the test chemicals were clear-cut, as were the secondary effects, such as reduced reproduction of daphnids at concentrations that reduced the algal population. The rate of loss of the chemicals from the water column was in proportion to the concentration of the chemicals and was reduced in jars that had been autoclaved and contained no biota.
An Overview of the Hydrologic Simulation Program-FORTRAN, a Simulation Model for Chemical Transport and Aquatic Risk Assessment
Authors: Barnwell TO
Published: March 2009

This paper reviews the development of the Hydrologic Simulation Program-FORTRAN (HSPF), a comprehensive simulation model for predicting watershed hydrology, water quality, agricultural chemical migration, and risk assessment. The model uses such information as the time history of rainfall, temperature, and solar intensity, and characteristics of the land surface, such as land use patterns, soil characteristics, and agricultural practices, to simulate the processes that occur in a watershed. The flow rate, sediment load, and nutrient and pesticide concentrations are predicted. The model takes these results and information about the stream channels in the watershed and simulates the processes that occur in these streams. This part of the simulation produces a time history of water quantity, quality, and chemical transport at any point in a watershed—the inflow to a lake, for example. For ease of presentation and interpretation, flexible routines are provided for statistical analysis of the simulation output. A risk assessment methodology to evaluate lethal and sublethal effects, using the median lethal concentration (LC50) and maximum acceptable toxicant concentration (MATC) as the key effects parameters, is part of the analysis.