bluuebunny/crossref_metadata_2025 huggingface dataset:
Stress and Temperature Dependence of Irradiation Creep of Selected FCC and BCC Steels at Low Swelling
Authors: Toloczko MB , Garner FA
Published: April 2008

A large amount of data on irradiation creep of face centered cubic (FCC) and body centered cubic (BCC) steels have been analyzed and published by the present authors, but a recent reanalysis of these data have provided further insight into irradiation creep behavior. The present paper looks at the stress and temperature dependence of creep at low swelling for selected 316 stainless steels and HT9 steels irradiated at temperatures from 400–670°C. Analysis of the creep data has revealed that a transition from a lower creep rate with a stress exponent of one to a higher creep rate with an unknown stress exponent occurs in FCC and BCC steels at moderate stresses, and the transition stress is approximately the same for both classes of steels. Due to limited data at higher stresses, the nature of the creep behavior at stresses greater than the transition stress cannot be unambiguously defined. One possibility is that the stress exponent is transitioning from a value of one to a value greater than one. Another possibility is that the creep compliance value is transitioning to a higher value while the stress exponent remains at a value of one. The creep compliance coefficients of the FCC and BCC steels have also been carefully reanalyzed in the regime where the stresses are lower than the transition stress, and in this regime there is a clear delineation in the creep compliance values between 316 stainless steels, titanium-modified 316 steels, and HT9 steels as a function of temperature.
Peculiarities of Structural and Behavioral Changes of Some Zirconium Alloys at Damage Doses of Up to 50 dpa
Authors: Kobylyansky GP , Novosyolov AE , Ostrovsky ZE , Shamardin VK , Obuhov AV , Shishov VN , Peregud MM , Nikulina AV
Published: April 2008

The irradiation-induced damage of zirconium alloys subjected to neutron irradiation up to dose levels of ∼50 dpa was investigated. Specimens of unalloyed zirconium, Zr-1%Nb, Zr-2.5%Nb and Zr-1%Nb-1.3%Sn-0.4%Fe were irradiated in the BOR-60 reactor over the temperature range 320–420°C. The dose dependence of the irradiation growth strain increased sharply in zirconium and Zr-Nb irradiated at ∼350°C at doses above ∼10 dpa. In the case of Zr-1%Nb-1.3%Sn-0.4%Fe, it increased at doses of ∼37 dpa. Upon increasing the irradiation temperature to 420°C, a sharp accelerated irradiation growth of the Zr-1%Nb alloy began shifting up to about 30 dpa. For the Zr- 1%Nb-1.3%Sn-0.4%Fe, no change of the irradiation growth rate was observed up to a dose of 55 dpa. The onset of increased irradiation growth in alloys correlates with the occurrence of c-component dislocation loops which coincides with a loss of coherence of finely-dispersed precipitates. Post-irradiation annealing experiments demonstrated that a delay in loop formation leads to displacement of the “break-away” beginning in the dose dependence of the irradiation growth in the direction of high doses. The -type dislocation loops were also formed in Zr-1%Nb alloy at high doses, but their influence on the change of macroscopic properties was not observed.

The high dose irradiation resulted in a change of composition: the hcp matrix solid solution was depleted in niobium; a gradient of concentrations was noted along the radius of (ZrNb)2Fe particles occurring in the Zr-1 %Nb-1.3%Sn-0.4%Fe. The microstructure of Zr-2.5%Nb quenched from β-phase and then tempered was investigated after irradiation up to high doses at the low temperature of $#x223C;80°C. Irradiation-induced precipitates of β- Nb were observed, with concentration increasing with increasing irradiation damage rate.
Development of a DCPD Calibration for Evaluation of Crack Growth in Corner-Notched, Open-Hole Specimens
Authors: George K , Reemsnyder HS , Donald JK , Bucci RJ
Published: April 2008

A direct current potential drop (DCPD) calibration was developed for an open-hole specimen to characterize fatigue crack growth (FCG) behavior of cracks initiating from a small corner flaw and transitioning to a through-thickness crack. A single Mode I stress intensity (KI) solution was derived covering the entire range of crack growth. The purpose of using this specimen geometry was to: 1) capture short crack behavior for specific crack length intervals of damage tolerance criteria and 2) use the data to evaluate predictive FCG methodology. Driven by these objectives, a non-standard specimen was chosen that better simulated the geometry and stress state of the component of interest: an aircraft wing design detail. Thin panels of selected 7XXX and 2XXX aluminum alloys were prepared with a centrally located open-hole with a corner notch of 0.13 mm (∼0.005 in.) to serve as a crack initiation site. Testing was conducted in high-humidity air under constant and variable amplitude loading. Short crack results agreed well with existing, closure-corrected, long crack data. Duplicate tests of the 7XXX alloys confirmed repeatability. The 2XXX alloys exhibited greater variability than the 7XXX alloys in the short crack regime. Evaluation of the predictive methods is beyond the scope of this paper and will be published separately.
A Model for the Inclusion of Notch Plasticity Effects in Fatigue Crack Growth Analysis
Authors: Ball DL
Published: April 2008

Notches or other stress concentrations are by far the most common sites for the initiation and growth of fatigue cracks in aircraft structures. The growth of these cracks is directly influenced by the material stress-strain response in the vicinity of the notch. Specifically, when the applied (remote) stress is sufficient to cause local plastic deformation at the notch, the response (local) stresses can no longer be found using elastic stress concentration factors, and they become dependent on the prior loading history. This is to say that the response stresses can no longer be treated as state variables. The occurrence of fatigue crack growth at notches which experience local yielding one or more times during their design lifetime is, in fact, quite common in many cyclically loaded structures. Some of the assumptions inherent in “traditional” Linear Elastic Fracture Mechanics (LEFM) based fatigue crack growth analysis may be inappropriate for such problems. In particular, the assumption that the stress distribution on a critical plane remains proportional to the elastic distribution throughout the loading history becomes incorrect when one or more of the applied loads causes plastic deformation and introduces or alters a residual stress field in this region. This paper first describes an elastic-plastic stress-strain response algorithm which may be used to estimate response stress distributions on a critical plane on a cycle-by-cycle basis. This is followed by a discussion of the manner by which stress intensity factors may be calculated based on these response stress distributions using Green's functions. Finally, the use of these stress intensity factors for the calculation of crack growth rate and, ultimately, crack growth life, is demonstrated.
Comparisons of Analytical Crack Closure Models and Experimental Results Under Flight Spectrum Loading
Authors: McClung RC , McMaster FJ , Feiger JH
Published: April 2008

Spectrum FCG data were generated with corner cracks at center holes for three contrasting spectrum types and two aluminum alloys, 2124-T851 and 7475-T7351. Existing strip-yield crack closure models for FCG analysis under spectrum loading were evaluated in comparison to conventional FCG models and enhanced as needed. Spectrum editing methods based on closure behavior were developed to reduce both computational and experimental time. FASTRAN was modified to address apparent differences in closure behavior between the surface and bore tips for compression-dominated spectra. Strip yield models successfully predicted FCG lives for contrasting spectra with a common constraint factor, unlike conventional models.
Degradation Parameters and Two-Stress Block Fatigue of Angle-Ply Carbon Fiber Reinforced Epoxy
Authors: Petermann J , Hinz S , Schulte K
Published: April 2008

Experimental studies on carbon/epoxy angle-ply laminates were conducted to prove different variables for their suitability as degradation parameters and to investigate frequency and load sequence effects. Within the investigated limits, the material did not behave in a frequency dependent manner. Although different damage mechanisms dominate at R = 0.1 and R = -1, the same degradation of fatigue strength per life decade was found. The variation of longitudinal stiffness and Poisson's ratio during fatigue life (the latter being considered superior to detect delaminations) exhibited load dependent characteristics. Under two-stress block fatigue, a significant effect of the load sequence on the fatigue life was found and different mechanisms were discussed.
Study on Fatigue Design Loads for Ships Based on Crack Growth Analysis
Authors: Tomita Y , Hashimoto K , Osawa N , Terai K , Wang Y
Published: April 2008

Although ship structural members are designed to survive 20 years, fatigue crack damage still occurs, often starting very early in the ship's life, with some cracks growing quickly to considerable size. The primary factor causing variability is the sequence of the variable amplitude load cycle, and the others are welding irregularities on the weld toe and variations in mechanical properties in the material. In this paper, the load sequence effect on fatigue life variability is examined by the use of a fatigue design procedure proposed by the authors. It is found that the fatigue lives of ship structural members vary from several months to 20 years, strongly dependent on the sequence of sea state which ships encounter during ocean-going service. The worst possible loading sequence is elucidated for the fatigue life of the ship's hull. Sensitivity study of fatigue life is discussed.
Life Prediction by Observation and Simulation of Short Crack Behavior in a Low Carbon Steel
Authors: Hünecke J , Schöne D
Published: April 2008

Short fatigue cracks were investigated in a 0.14 wt % carbon steel (SAE 1017) in fine grained condition by optical observation of the surface of smooth specimens under fatigue loading. Axial fatigue experiments were carried out under constant and step amplitude conditions. The lifetime to crack initiation was calculated for each ferrite grain with regard to grain size and orientation. For the calculation of crack propagation, the slip band length (grain size) and the distance between crack tip and next barrier (grain boundary) are taken into consideration. Furthermore, the simulation program includes some geometrical aspects for the description of crack coalescence.
Pullout Resistance of Roofing Fasteners Using Different Methods
Authors: Baskaran A , Sexton M , Lei W , Molleti S
Published: April 2008

Wind uplift rating is one of the key performance requirements for single-ply mechanically attached systems. It depends on the properties of the membrane (mechanical, physical and chemical), substrate (compressive strength and dimensional stability), and deck (thickness and deflection). An attachment system (fastener, plate and seam) integrates the above components to form an assembly. Fastener pullout resistance (FPR) from the deck is one of the essential design parameters in the system specification. As well, the FPR is an indicator of the existing deck condition in reroofing/recover applications. In the field, the FPR values are obtained using pullout testers. To quantify the accuracy of the manual pullout testers under various environmental conditions, an experimental program is in progress at the National Research Council's Dynamic Roofing Facility (DRF). From this ongoing research, this paper compares the FPR data from the field pullout tester with those obtained using the laboratory universal Instron testing machine. In the manual pullout tester, consistency of the FPR data depends on the operator. Considering this variable and to generalize the data, the above experiments are performed on two decks (steel and wood) with three different fastener types. The study finds that the field manual pullout tester underestimates the FPR data in comparison to the data obtained from the laboratory machine. This trend is found true irrespective of the selected decks and fasteners. In the roofing market, automatic pullout testers are also available that function using a battery-powered source. Selected experiments were performed to identify the influence of the pull out speed on the FPR data using an automatic pullout tester.
The Effect of Reflective Roof Coatings on the Durability of Roofing Systems
Authors: Mellott JW , Portfolio DC
Published: April 2008

Based on the knowledge obtained from the Roof Coatings Manufacturers Association (RCMA) sponsored Oak Ridge National Laboratory studies completed in 2000, the RCMA is launching a new long-term durability study. In the original study, preliminary data indicated that reflective coatings retarded the degradation of built-up roofing systems. This part of the study was minimal in scope and incidental to the original test program. As a result this new, more inclusive study is being undertaken.

In the new study the effect of seven reflective coatings and a control will be determined over four different roofing membranes. The purpose of the study is to determine the long-term effect of the coatings on performance properties of the roofing membrane systems by the applied reflective coatings. The coatings used in the study will be selected from commercially available products. The roofing systems will be exposed in three different geographic regions: the midwest, the southeast and the southwest. The membranes will include a granule surfaced SBS membrane system, a smooth APP membrane system, a standard built-up roof system, and a black, non-reinforced EPDM membrane.

The reflective roof coatings selected include two types of fibered aluminum coating, one white styrene acrylic elastomeric coating, one white acrylic elastomeric coating, one white solvent based elastomeric coating, one water-based aluminum coating, and a standard fibered black asphalt emulsion coating. The systems will be periodically tested throughout the aging process for a group of physical properties related to performance.

Concurrent with the outdoor exposure, accelerated aging will be conducted using two conventional weathering techniques. The objective in this part of the study is to determine if there is a correlation between accelerated aging and in-field exposure. The subsequent effect of accelerated weathering on changes in reflectance and emissivity will be determined. The accelerated data will be compared to existing 3-year in-field data to determine if there is a correlation between the accelerated weathering and real time weathering.
A Comparison of the Glass Transition Temperatures of Artificially Aged and Field-Aged Roof Membranes Through the Use of Dynamic Mechanical Analysis
Authors: De Leon CC , Diebel PW , Delgado AH , Paroli RM
Published: April 2008

The authors studied the effect of heat and ultraviolet (UV) exposure as well as natural weathering on the glass transition temperature of PVC roof membranes. The glass transition temperature of the unexposed specimens and those exposed to heat, artificial (UV) and natural weathering obtained from the E' and E" curves, as per ASTM Practice for Dynamic Mechanical Analysis and Thermogravimetry of Roofing and Waterproofing Membrane Material (D 6382) and ASTM Test Method for Plastics: Dynamic Mechanical Properties: In Flexure (Dual Cantilever Beam) (D 5418), range from -48°C to -33°C and from -39°C to -28°C, respectively. The ΔTg values obtained from the E' curve varied between -6°C and 4°C and those from the E" curve varied between -4°C and 9°C. The results indicate that some naturally exposed membranes have similar ΔTgs to some of the artificially aged samples.
Update: Service Life Tests for Roofing Membranes
Authors: Bailey DM , Cash CG , Davies AG
Published: April 2008

This research measured selected physical characteristics of twelve roofing membranes before and after oven heat and ultraviolet exposure. To make these data useful for comparing values, identical test methods and conditions were used for each membrane. We intend to compare these data with before and after exposure data obtained on companion samples exposed outdoors at three locations in the United States in an effort to determine the laboratory program that might accurately predict the performance of roofing membranes.
Evaluation of Different Techniques for Adhesive Properties of Asphalt-Filler Systems at Interfacial Region
Authors: Huang S-C , Turner TF , Pauli AT , Miknis FP , Branthaver JF , Robertson RE
Published: April 2008

Asphalt is a widely variable product used in public roadways at the rate of 30 million tons per year and is thus the largest volume of adhesive used in any application. Considering the commercial importance of asphalt, several analytical techniques were employed to investigate its adhesive properties. These techniques include the specially designed sliding plate viscometer, differential scanning calorimetry (DSC), atomic force microscopy (AFM), liquid chromatography, centrifugation, and infrared (IR) spectroscopy. The specially designed sliding plate rheometer was used to measure the Theological properties of asphalt film in contact with aggregate surface at thin film levels. DSC was applied to measure the effect of fine particles on the low temperature properties. AFM was used to produce a photo-like image of adhesion between asphalt and mineral fines. Chromatography and centrifugation techniques were used to separate the adsorbable, polar asphalt components from aggregate surfaces. Infrared spectroscopy was used to determine the quantities and natures of adsorbed molecules. The results of these asphalt-aggregate experiments have shown what types of organic molecules in asphalt adsorb onto aggregate surfaces. Aggregates are shown to adsorb large concentrations of the most polar functional groups found in asphalts. In addition, the theory of Interfacial Morphological Stability has been used to model air-asphalt film and asphalt film-glass substrate interfacial systems. Separately, a wet-packing chromatographic technique was developed to use pulverized aggregate to separate cyclohexane solutions of asphalt into polar and non-polar components. Furthermore, the DSC evidence suggests the immobilization of a surface layer of binder in contact with aggregate induces a large rigid, amorphous fraction of the binder. These methods have been employed to characterize the fundamentals of asphalt-aggregate interaction in order to devise improved road performance predictive tests.
Estimating Functional Connectivity of Wildlife Habitat and Its Relevance to Ecological Risk Assessment
Authors: Johnson AR , Allen CR , Simpson KAN
Published: April 2008

Habitat fragmentation is a major threat to the viability of wildlife populations and the maintenance of biodiversity. Fragmentation relates to the sub-division of habitat into disjunct patches. Usually coincident with fragmentation per se is loss of habitat, a reduction in the size of the remnant patches, and increasing distance between patches. Natural and anthropogenic processes leading to habitat fragmentation occur at many spatial scales, and their impacts on wildlife depend on the scales at which species interact with the landscape. The concept of functional connectivity captures this organism-based view of the relative ease of movement or degree of exchange between physically disjunct habitat patches. Functional connectivity of a given habitat arrangement for a given wildlife species depends on details of the organism's life history and behavioral ecology, but, for broad categories of species, quantities such as home range size and dispersal distance scale allometrically with body mass. These relationships can be incorporated into spatial analyses of functional connectivity, which can be quantified by indices or displayed graphically in maps. We review indices and GIS-based approaches to estimating functional connectivity, presenting examples from the literature and our own work on mammalian distributions. Such analyses can be readily incorporated within an ecological risk framework. Estimates of functional connectivity may be useful in a screening-level assessment of the impact of habitat fragmentation relative to other stressors, and may be crucial in detailed population modeling and viability analysis.
Application of Habitat Suitability Index Values to Modify Exposure Estimates in Characterizing Ecological Risk
Authors: Kapustka LA , Galbraith H , Luxon M , Yocum JM , Adams WJ
Published: April 2008

We developed an approach intended to improve the accuracy and relevancy of ecological risk assessments (EcoRA), facilitate communication of decisions, and control overall project costs. An Access® database containing data for 91 Habitat Suitability Index (HSI) Models species and a Correspondence Matrix, which cross-lists all wildlife species of the US in terms of similar habitat preferences and similar dietary patterns were prepared. An iterative approach was used to: (a) select candidate assessment species; (b) prescribe data collection needs for characterization of habitat quality; (c) generate spatially explicit descriptions of habitat quality for assessment species; and (d) allocate exposure estimates using habitat quality and distributions of chemical concentration. Information from a previous EcoRA conducted for Kennecott Utah Copper was used to evaluate the efficacy of the approach. Vegetation polygons across the 360-km2 area of the site were generated from infrared aerial photographs. HSI values were calculated for each polygon for selected assessment species. HSI values then were used to modify exposure estimates for selected CoC. Qualitative comparisons of these modified exposure estimates to the findings of the original risk assessment illustrate that the approach would improve the accuracy and relevance of the risk estimates.
Sunflower Depredation and Avicide Use: A Case Study Focused on DRC-1339 and Risks to Non-target Birds in North Dakota and South Dakota
Authors: Linder G , Harrahy E , Johnson L , Gamble L , Johnson K , Gober J , Jones S
Published: April 2008

Agricultural land-use, cropping practice, agrichemical use, and wildlife interactions have long provided conflicts between wildlife needs and human uses of habitat. For example, sunflower seeds ripening in late summer and early autumn throughout agricultural areas of North Dakota and South Dakota are highly sought food items for red-winged blackbirds, common grackles, and yellow-headed blackbirds. Unfortunately, loss of sunflower seeds prior to fall harvest has been attributed to these birds, with crop losses estimated at greater than $5 million per year. An avicide, DRC-1339 (3-chloro-p-toluidine hydrochloride), has been proposed for use in spring baiting Programs in North Dakota and South Dakota to control fall depredation of the sunflower crop. An estimated 60 species of non-target birds with varying sensitivities to DRC-1339 occur near spring baiting sites, with nearly half of these species being granivores that might feed on the DRC-1339-treated bait. At least nine species are birds of management concern. Our work evaluated risks to non-target birds that are potentially associated with DRC-1339 spring baitings. From the current analysis, spring baiting presents risks to non-target birds, especially small-bodied species characterized by marked responsiveness to DRC-1339, e.g., ingestion of a single baited grain will likely yield mortality in a small-bodied bird. A simple comparison of hazard quotients for small-bodied nontarget birds and target birds suggests these species have similar risks for dietary exposures to DRC-1339. At present mitigation practices are unproven with respect to minimizing non-target bird loss. Potential losses from non-target populations resently thought to be declining suggests that risks vary across the relatively simple “non-target” category, and risk managers must be wary of oversimplifying management plans based on a “non-target” and “target” categorization of species at-risk. In view of the uncertainties apparent in the present analysis, as well as other risk assessments focused on the issue, decisions regarding DRC-1339's use hinge on differing management perspectives of “acceptable risk” and resource valuation. Only when these issues are resolved can resource management plans benefit the long-term sustainability of resources at risk.
GIS-Based Localization of Impaired Benthic Communities in Chesapeake Bay: Associations with Indicators of Anthropogenic Stress
Authors: Preston BL
Published: April 2008

Current ecological risk assessment methodologies have limited capacity to account for the spatial heterogeneity in Stressors and physical/chemical conditions characteristic of aquatic and estuarine ecosystems. The Shannon-Weaver index was utilized to construct spatial models of benthic macroinvertebrate biodiversity in Chesapeake Bay over several time periods between 1987–2001. These models were subsequently compared to monitoring data for sediment contaminant concentrations and physical/chemical water quality conditions. A series of GIS exercises demonstrated that low values for species diversity were associated with higher concentrations of a diverse array of contaminants as well as physical/chemical water quality conditions. Multivariate regression analysis among a range of contaminant and water quality variables accounted for up to 61% of the observed variation in benthic biodiversity. Collectively, these results demonstrate the numerous challenges for conducting ecologically relevant risk assessments at the ecosystem level, which can be partially ameliorated with quality monitoring data and geographic approaches to environmental assessment.
Risk-Trace: Software for Spatially Explicit Exposure Assessment
Authors: Linkov I , Grebenkov A , Andrizhievski A , Loukashevich A , Trifonov A
Published: April 2008

Large areas of valuable habitats have been physically disturbed and/or contaminated by hazardous pollutants as a result of industrial activities. This paper presents a methodological approach and a software prototype for spatially explicit risk assessment of contaminated terrestrial ecosystems, to be implemented as a part of a risk-based decision protocol to support the assessment of ecological value and site reuse options. Exposure estimates for wildlife in areas containing spatially localized contaminants are functions of spatial factors, such as the receptor's average foraging area, the size of the habitat being assessed, and the distribution of contamination. Species exhibiting different foraging strategies may experience significantly different chemical exposures from the same site, even if their foraging areas overlap. Currently, exposure estimates and subsequent human health and ecological risk projections usually assume a static and continuous exposure of an ecological receptor to a contaminant concentration represented by some descriptive statistic, such as the mean or maximum concentration. These assumptions are generally overly conservative and ignore some of the major advantages offered by advanced risk assessment techniques, such as the ability to account for site-specific conditions and to conduct iterative analyses. We developed a spatially explicit foraging model that provides a time series estimation of soil and food contamination that receptors may encounter in their daily movements. The model currently inputs information on: the geospatial parameters of the contaminated area, surrounding land, and the habitat types found in each; density and distribution of ecological receptors; receptor home range; maps of contamination concentrations and habitat disturbance; and receptor's foraging range. The model also employs habitat quality factors that account for differential attraction to various habitat types within the site. This paper presents a software prototype that calculates chemical accumulation by a receptor foraging in areas having specified contamination patterns and habitat parameters.
Incorporating Spatial Data into Ecological Risk Assessments: The Spatially Explicit Exposure Module (SEEM) for ARAMS
Authors: Wickwire WT , Menzie CA , Burmistrov D , Hope BK
Published: April 2008

Although the tools available to ecological risk assessors have become more sophisticated, the basic questions remain the same. Foremost among those questions is what spatial scale is appropriate from an ecological, toxicological, operational and regulatory perspective for the ecological risk assessment. Once a spatial scale has been defined, the risk assessor needs useful modeling tools with enough power to evaluate exposure at the selected spatial scale and models that include a consideration of not only the physical size of an assessment area, but also the habitat suitability with respect to the needs of a number of wildlife species. To address this need, our team developed a spatially explicit exposure module (SEEM) for the U.S. Army that considers these aspects for some terrestrial wildlife species. SEEM offers the risk assessor the opportunity to improve the ecological relevance of the risk assessment by considering spatial aspects of exposure through an evaluation of heterogeneous habitat use and chemical patterns and a comparison of exposure with the potential for toxicological effects, resulting in a population measure of risk. SEEM predicts and compiles exposures for all individuals within a local population, rather than a single representative individual. In addition, SEEM increases the predictive capabilities of the exposure assessment by incorporating habitat preferences in the determination of daily exposure estimates. The model will track an individual over an ecologically-relevant period of time as it travels across a landscape. The individual will move according to a set of predetermined rules and exposure for a population of individuals will be tracked over time. The module is being developed for inclusion within the U.S. Army Risk Assessment Modeling System (ARAMS).
Flowable Fill Using Flue Gas Desulfurization Material
Authors: Butalia TS , Wolfe WE , Zand B , Lee JW
Published: April 2008

Flowable fills are an effective and practical alternative to commonly used compacted earth backfills. Flowable fill is a cementious material, commonly a blend of cement, fly ash, sand, and water, that does not require compaction, may be self-leveling at time of placement, may harden quickly within a few hours, and can be excavated in the fixture if need be. Many flue gas desulfurization (FGD) materials have low unit weight and good shear strength characteristics and thus hold promise for flowable fill applications. This paper focuses on the potential of using two types of FGD materials (spray dryer and wet fixated FGD material) in flowable fill as a replacement for conventional fly ash. Several design mixes were considered. The design mixes consisted of varying amounts of FGD material, cement, lime, and water. The mixes were tested in the laboratory for flowability, unit weight, moisture content, unconfined compressive strength, erodibility, set-time, penetration, and long-term strength characteristics. Tests were conducted for up to 90 d of curing. Without any additives, the FGD material was observed to be as good as a regular (normal set) flowable fill in terms of placeabiliry, unconfined compressive strength, and diggability. FGD material flowable fill with additives and admixtures compares favorably with the characteristics of conventional quick set flowable fills.
Improving the Effectiveness of Aerial Pesticide Sprays
Authors: Smith DB , Kirk IW , Ross JB
Published: April 2008

Thirty-eight aircraft setups were submitted in order to have droplet size and drift analyses performed. Four of the eleven insecticides predicted Dv0.5s were in the 351–400 μm range. Seven of the herbicide setups had predicted Dv0.5s in the 205–250 μm range, while ten Dv0.5s were > 351 μm. Five of the ten predicted Dv0.5s were between 386 and 413 μm. Twelve different herbicides were reported as having been applied with aircraft setups that had predicted Dv0.5s between 386 and 413 μm. A summary of the prior swath deposit data indicated that the percent recovery generally increased as the Dv0.5 increased. The magnitudes of the deposits on inert targets and cotton leaves appeared to be about equal for a given Dv0.5. The correlation coefficient between the “percent of the spray volume in droplets ≤ 100 μm and ≤ 200 μm in diameter” was 0.983. This result is consistent with prior results and indicates that either 100 or 200 μm can be effectively used as the upper limit when studying the “small droplet” component in sprays. We found several similarities or differences in the “small droplet” components based on data from different atomization tests. According to one set of atomization models, agricultural aircraft will be limited to about 225 km/h (i.e., 140 mph) in order to produce a 400 μm Dv0.5 spray when using currently available nozzles and water plus one or more pesticides. The extremes of the predicted drift deposits for 38 agricultural aircraft setups were over 30-fold apart.
Neutron Spectrum Effect and Damage Analysis on Pressure Vessel Steel Irradiation Behaviour
Authors: Pichon C , Brillaud C , Deydier D , Alberman A , Soulat P
Published: April 2008

A comprehensive program on pressure vessel irradiation behaviour has been carried out by the Commissariat à l'Energie Atomique (CEA) and Electricité de France (EDF) from 1989 until 1995. This program is a key approach to EDF plant life assessment strategy. It is based on experimental correlations between pressure vessel steel irradiation behaviour with regard to fluences obtained in two very different irradiation spectra specially designed in the OSIRIS and SILOE CEA test reactors. The aims of this program were to assess a potential neutron spectrum effect in the range met in a Pressurised Water Reactor (PWR) between the vessel (internal surface, 1/4 thickness) and the surveillance capsules and correlatively to define the most appropriate exposure parameter for low alloy steel embrittlement.

In order to fulfill this objective, all experimental parameters had to be accurately controlled. New high-capacity irradiation rigs have been therefore developed by the CEA to test two materials in parallel with a large number of Charpy-V specimens in well-defined conditions (temperature, neutronic environment). Two weld materials were specifically manufactured from low alloy Mn Ni Mo steel. In terms of embrittling elements (Cu, Ni, P), these materials are representative of average and upper bound chemical compositions found in French nuclear power reactor vessel welds. Target fluences were 0.1 dpa in both reactors, corresponding to 7.1019 n.cm-2 (ΦE>1MeV) in the OSIRIS standard spectrum and to 4.1019 n.cm-2 (ΦE>1MeV) in the SILOE “distorted” spectrum. The spectra characteristics were derived both by damage monitor dosimetry and neutron transport calculations. For each material in each state, Charpy-V transition curves were defined.

The results in terms of Charpy-V transition shifts and fluences (ΦE>1MeV, ΦE>0.1MeV and Φdpa) are presented then discussed. In the range considered, no spectrum effect and a very good correlation using fluence ΦE>1MeV were found.
Effects of Neutron Irradiation on Fe-Cu Model Alloys and RPV Steels Probed by Positron Annihilation and Hardness Measurements
Authors: Hempel A , Saneyasu M , Tang Z , Hasegawa M , Brauer G , Plazaola F , Yamaguchi S , Kano F , Kawai A
Published: April 2008

To study the formation of microvoids and Cu precipitates in Fe-Cu mode alloys (0–1.0 wt. % Cu) and A533B reactor pressure vessel (RPV) steel, positron lifetime and Vickers microhardness have been measured after fast neutron irradiation to a fluence of 8.3×1018n/cm2 below 150°C. Long positron lifetimes for the Fe-Cu alloys ranging from 300 to 420 ps and 270 to 350 ps for A533B RPV steels have been observed, which show microvoid formation. The long lifetimes in the Fe-Cu alloys depend on the Cu content and thermal aging at 550°C before irradiation. This fact suggests incorporation of irradiation-induced vacancies at Cu atoms and their precipitates leading to suppression of the microvoid formation. The long lifetime component for the Fe-Cu alloys recovers around 350°C, while that for A533B steel recovers around 300°C. To estimate the microvoid sizes, superimposed-atom model calculations of positron lifetimes in microvoids consisting of 1 (V1) to 66 (V66) vacancies have been performed, respectively. Based on these calculations, the formation and post-irradiation annealing behaviour of microvoids are examined.

In addition, irradiation-induced hardening monitored by Vickers microhardness is discussed with reference to positron annihilation experiments.
Irradiation Behavior of Ferritic-Martensitic 9–12%Cr Steels
Authors: Horsten MG , van Osch EV , Gelles DS , Hamilton ML
Published: April 2008

A dedicated series of irradiation experiments has been executed in the high flux reactor (HFR) in Petten (Netherlands) to evaluate the irradiation behavior of ferritic-martensitic 9–12%Cr steels at temperatures in the range of 70°C to 370°C and damage dose levels up to 3 dpa. Materials investigated in the program comprise Mod.9%Cr (9Cr-1Mo-0.2V-0.08Nb), HT9 (12Cr-1Mo-0.5W-0.5Ni-0.3V), MANET type steel (10Cr-0.5Mo-0.6Ni-0.2V-0.15Nb), NF616 (9Cr-2W-0.5Mo-0.2V-0.07Nb) and HCM12A (12Cr-2W-1Cu-0.4Mo-0.3Ni-0.2V-0.05Nb). The 9–12%Cr steels show severe hardening and ductility reduction at room temperature (RT) after neutron irradiation. Strength, ductility and toughness of material irradiated at 70°C gradually recover with increase in test temperature. Similar ductility trends of material irradiated at 300°C are observed as for unirradiated material, but recovery with increase in temperature is not observed below temperatures of 400°C. The 9%Cr steels show less hardening and reduction in ductility than the 10–12%Cr steels. The reduction of area and 0.2% yield stress correlate well with the upper-shelf energy and ductile-to-brittle transition temperature, respectively, both for the unirradiated and irradiated condition. In general, the 9%Cr steels show more resistance to irradiation at 300°C than the 10–12%Cr steels with respect to fracture toughness.
The Relationship Between Swelling and Irradiation Creep in 20% Cold-Worked 316 Stainless Steel
Authors: Garner FA , Toloczko MB , Puigh RJ
Published: April 2008

The relationship between swelling and irradiation creep was investigated using eight sets of pressurized tubes, representing two heats of 20% cold-worked 316 stainless steel irradiated at either 550°C, 575°C, 600°C, and 670°C in the FFTF-MOTA to doses of 79–84 dpa. After reaching these exposures, the tubes were clearly being affected by the “creep cessation” phenomenon. Many of the tubes had already reached the previously observed maximum strain rate of 0.33%/dpa characteristic of creep cessation. Fortuitous failure of fourteen tubes allowed the separation of creep and swelling strains in the creep cessation regime, showing that the maximum strain rate limitation was reached long before the maximum swelling rate of 1%/dpa was reached. Thus, the creep contribution was declining as the swelling rate increased throughout the irradiation.
On the Role of Internal Stresses in Void Denuded Zone Formation Under HVEM-Irradiation of Metals and Alloys Preconditioned by Reactor Exposure
Authors: Konobeev YV , Pechenkin VA , Garner FA
Published: April 2008

Irradiation of thin metallic foils in a High Voltage Electron Microscope (HVEM) has been widely used for investigating void swelling. One of the observations in HVEM experiments is the formation of void denuded zones in foils prepared from metals and alloys preconditioned by neutron irradiation. Under electron irradiation, pre-existing voids shrink in regions near foil surfaces. Such a shrinkage is thought to occur without any transfer of vacancies to other voids and is proposed to be related to the interstitial flux exceeding the vacancy flux into near-surface voids. In the present paper internal stresses arising due to non-uniform swelling under conditions of HVEM irradiation are taken into consideration. It is demonstrated that by assuming the presence of sufficiently large stress gradients within the foil one can explain the origin of the void shrinkage in near-surface zones and also explain why a swelling enhancement is often observed on the boundary of the voided zone.
Temperature-Shift of Void Swelling Observed in Annealed Fe-18Cr-10Ni-Ti Stainless Steel Irradiated in the Reflector Region of BOR-60
Authors: Neustroev VS , Shamardin VK , Ostrovsky ZE , Pecherin AM , Garner FA
Published: April 2008

Evidence has been provided to support the “temperature-shift” concept of swelling. The swelling of annealed X18H10T stainless steel in the BOR-60 fast reactor at PWR-relevant dpa rates was found to be higher than predicted by a swelling equation developed from data obtained at dpa rates almost an order of magnitude higher. These data were derived from identical hexagonal wrappers irradiated in both in-core and reflector positions. Based on these results, irradiation in PWRs would yield higher swelling to lower temperatures than would occur in core regions of fast reactors.
Stress-Affected Dislocation Development of Stainless Steel During Neutron Irradiation
Authors: Porollo SI , Konobeev YV , Kruglov AS , Pevchikh YM , Garner FA
Published: April 2008

When stainless steels are irradiated at 530°C with neutrons to ∼0.2 dpa at stresses above the yield stress, the evolution of dislocation microstructure is very different from that which occurs when stresses are held below the yield stress. The dislocation network that forms is more uniform and crystallographically-oriented than the cell structure that forms in the absence of irradiation. Small defect clusters form instead of Frank loops, but their density decreases with the applied stress level.

Whereas network dislocations, defect clusters and Frank loops evolving at lower stress levels primarily communicate indirectly through their competition for point defects, stress-induced glide of dislocations is strongly activated above the yield strength and there is a strong, direct physical interaction between dislocations and loops that changes the nature of the saturation state of both components.
Stationary Rack and Black Box Under Glass Exposures of Mineral Filled Polyethylene in Inland and Marine Tropical Climates
Authors: Veleva LP , Valadez-Gonzalez A
Published: April 2008

During the past few years the accelerated weathering in natural condition tests has been attracting the attention of several researchers. From 1996 to 1998, CaCO3-filled HDPE samples were exposed to degradation on a stationary rack (SR) in a field test and in a “Black Box” (BB), the accelerated natural one, carried out according to ASTM G 24, G 7 and D 4141, in the tropical humid climate of the Peninsula of Yucatan (Mexico), in two typical environments: marine-coastal (MC) and rural-urban (RU). The daily analysis of the Temperature/Relative Humidity (T/RH) complex and based on its Time of Wetness (TOW) values showed that there is a significant difference between both test environments. Periodically the polymeric specimens were evaluated using FTIR, DSC and solution viscometry to establish the photo degradation kinetic process. The results show that the BB accelerated test does not change but accelerates the degradation mechanism of the tested polymer in both environments. Also, this acceleration is higher for the RU than the MC environment.
Predicting the Durability of Building Stone Using Accelerated Weathering
Authors: Bortz SA , Wonneberger B
Published: April 2008

The importance of weathering of building stone is becoming widely recognized, and there is a need in modern thin stone design (less than 2 inches) to be able to estimate their durability. Stone deterioration processes include a number of agents, including salts, air pollution, freeze-thaw and biodeterioration. While the weathering properties of dimension stone can be judged by the examination of buildings in which it has been used, this method cannot estimate the durability of a different stone, a stone from a different part of the same quarry, a stone from a new quarry, or if the stone is to be used under different environmental conditions. Data is presented in this paper to show a correlation can be determined between natural and accelerated weathering of building stones. Real timeline information has been obtained by comparing accelerated weathering test data with data that is obtained from naturally weathered stone specimens. An estimate can be made to assess the life expectancy of a building stone subjected to natural weathering by using the accelerated weathering test procedure described in this paper. Based on our studies, 12 to 16 freeze-thaw cycles of the test procedure can be considered approximately equal to one year of natural weathering in the Chicago area.
Calculation of The Spectral Irradiance of Solar Radiation for the Lifetime Prediction of Polymer Materials
Authors: Kockott D , Manier G
Published: April 2008

The calculation program under consideration determines the spectral irradiance of direct solar radiation, diffuse solar radiation and reflected radiation as well as global radiation as a factor of sun position (as determined by geographic location, season and time of day) and meteorological conditions: temperature and relative humidity, O3 concentration, degree of cloud cover and visibility as well as the spectral ground reflectance. Spectral irradiance levels are calculated for randomly positioned surfaces. The irradiance level is calculated as a function of time of day on the basis of the hourly means for the meteorological parameters as measured by many different weather stations. On this basis, the radiant exposure for a given day is calculated in terms of selectable wavelength ranges. The program also calculates the effective radiant exposure by using the spectral sensitivity of a specific material as a basis for lifetime prediction. The lifetime of a polymer material depends on several external parameters, e.g., solar radiation, temperature and moisture content of the material. The general scope of this paper is restricted to radiation and its effect on lifetime.
Selection of Metal for Oxygen Valves
Authors: Fano E , Faupin A , Barthelemy H
Published: April 2008

The document ASTM G.94.92 “Standard Guide for Evaluating Metals for Oxygen Service ” gives a complete guidance for the selection of metals. The different test methods are explained and a metal ranking table is given for each method. The best-known test is promoted combustion as described in ASTM G.124-95 “ Standard Test Method for Determining the Combustion Behaviour of Metallic Material in Oxygen Enriched Atmospheres ”. In this ranking aluminium bronze with only 9 to 13% aluminium is near aluminium and is therefore considered less resistant than any stainless steel.

This result is not consistent with the paper “ Ignition Testing of Hollow Vessels Pressurised with Gaseous Oxygen ” [1]. The particle impact test performed by NASA as described by Benz, et al [2] also gives a better ranking for aluminium bronze, between Inconel 600 and 625.

Analysing how ignition occurs in oxygen pipeline networks, we considered that the most probable cause is promoted ignition by particles. New rankings of metals are established in the case of impact on bulk materials by burning particles. Two theoretical rankings are based on interface temperature associated with a critical temperature, while another ranking is based on the results of tests made on the gaseous oxygen impact apparatus, with the addition of particles. Measurements of interface temperatures for different metals confirm the theoretical values. A comparison of the different rankings is discussed for metal selection for oxygen valves and it appears that stainless steel and aluminium bronze with 9 to 11% aluminium are equivalent choices for oxygen valves.