bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Contribution of Irradiation Growth to Pressure Tube Deformation
Authors: Holt RA , Fleck RG 
Published: March 2009

Up-to-date growth results on Zr-2.5Nb pressure tube material from the DIDO reactor at AERE Harwell are presented. The observed temperature dependence and magnitude of growth are significantly different from the representations in a recently published model for in-reactor deformation of pressure tubes. These differences are discussed in terms of (1) the effects of stress on growth, (2) the comparability of test reactor and power reactor conditions, and (3) the relative contributions of creep and growth to pressure tube elongation.
A preliminary estimate of the anisotropic creep component of the in-service deformation suggests that the creep anisotropy may be different from that in the model (derived from small specimen stress relaxation tests). Biaxial in-reactor creep tests on specimens with microstructures and textures similar to pressure tubes are required to support this view. This would also help to resolve an apparent discrepancy in the temperature dependence of growth and pressure tube elongation.
Influence of Alloy Composition and Processing on the Nodular Corrosion Resistance of Zircaloy-2
Authors: Bradley ER , Schemel JH , Nystöm A-L 
Published: March 2009

Zircaloy-2 fuel tubing with different compositions has been manufactured by a variety of thermomechanical processes to evaluate manufacturing variables that could influence nodular corrosion. The primary variables studied include: (1) alloy composition. (2) thermal annealing history, (3) tube texture, and (4) recrystallized versus stress relieved tubing. A total of 48 tubing variants were fabricated and tested.
Results from 793 K steam autoclave tests revealed that all variables examined influence the corrosion behavior with complex interactions between the variables. Alloy composition and thermal history exhibited the strongest influence. Improved corrosion resistance was observed for the material containing a lower Sn concentration and annealed at lower temperatures. The effect of thermal history was not consistent with the accumulated annealing parameter formulation. A single 1005 K anneal late in the manufacturing process produced extremely high weight gains compared to lower values when the same anneal occurred early in the process or when annealing for longer times at lower temperatures to obtain the same accumulated annealing parameter. Small improvements in corrosion resistance for the more sensitive materials were obtained from tubing produced with a more radial texture. Stress relieved tubing was generally less sensitive to nodular corrosion than comparable recrystallized tubing.
Microstructural examinations did not identify the cause for the observed variations in corrosion behavior. Particle size distributions were independent of the material or processing histories. This lack of any correlation indicates that the particles themselves do not control the corrosion behavior, but a specific microstructural feature was not found that would explain the corrosion behavior.
Oxide Growth Mechanism on Zirconium Alloys
Authors: Garzarolli F , Seidel H , Tricot R , Gros JP 
Published: March 2009

In order to get a better understanding of the mechanisms governing corrosion of Zr-based alloys, several examinations have been performed on a variety of samples with uniform and nodular corrosion and different oxide layer thicknesses.
The results point to a barrier layer concept. The oxide layer becomes porous at a critical thickness. Open porosity increases from 0.01% at 10 μm to 3% at 100 μm. Between the outer porous oxide and the metal, a dense interlayer exists. This is only ≤30 nm in nodular oxide but has been found to be several hundred nm in uniform post-transition oxide.
The barrier layer is obviously influenced by the crystallization of the oxide at the interface. This crystallization leads either to a columnar monoclinic, an equiaxed tetragonal, or to a fine equiaxed monoclinic oxide. The latter, which probably forms only under the mineralizing effect of hydrogen, was found in nodular oxide. It easily cracks at the grain boundaries. Well developed columnar oxide is seen in uniform oxide, when corrosion resistance is high.
Recrystallization seems to be responsible for the pore or microcrack formation at the transition. The intermetallic precipitates influence the corrosion behavior significantly. They probably oxidize slowly. This oxidation starts with the zirconium and is accompanied by iron diffusion into the surrounding oxide.
Raman Spectroscopy Study of the Tetragonal-to-monoclinic Transition in Zirconium Oxide Scales and Determination of Overall Oxygen Diffusion by Nuclear Microanalysis of O18
Authors: Godlewski J , Gros JP , Lambertin M , Wadier JF , Weidinger H 
Published: March 2009

Two allotropic forms of zirconium oxide, monoclinic and tetragonal, have been identified in the scales formed on zirconium alloys. The transition from tetragonal to monoclinic has been followed by X-ray measurements and Raman laser spectroscopy. Information on the average content of the tetragonal phase was obtained by X-ray diffraction, whereas Raman laser analyses on tapered sections revealed its distribution through the scale thickness.
Oxidation exposures were made in an autoclave, using H2O18 and D2O18 to determine the overall diffusion coefficients. In particular, oxide scales have been studied on Zircaloy-4 with three different precipitate sizes, and on a Zr-1Nb alloy, after exposure in an autoclave for between 3 and 100 days. The specimens were analyzed in detail in the vicinity of the kinetics transition point, where the acceleration of corrosion occurs.
Raman spectroscopy analyses enabled the crystallographic nature of the ZrO2 to be determined. Close to the interface, the tetragonal phase content is about 40%, when after the transition the tetragonal phase is transformed into monoclinic.
The O18 diffusion treatment was carried out in an autoclave at 400°C under pressure on specimens previously oxidized for between 3 and 100 days in natural water vapor pressure. The diffusion profiles were determined by nuclear microanalysis using the O18(p,α)→N15 reaction. Based on these profiles, the volume and grain boundary diffusion coefficients were calculated for each material and for each oxidation time.
The results show clearly that oxygen transport occurs principally by grain boundary diffusion. The boundary diffusion coefficient is 108 times higher than those for bulk diffusion (Db is equal to 10-13 to 10-15 cm2/s).
The results of these analyses are in agreement with the changes in kinetics observed at the transition point. The stabilization of the tetragonal phase by stress is discussed.
Corrosion-Electrochemical Properties of Zirconium Intermetallics
Authors: Weidinger HG , Ruhmann H , Cheliotis G , Maguire M , Yau T-L 
Published: March 2009

Alpha-zirconium is a very poor solvent for most alloying metals. Moreover, it has a high affinity for these metals. Consequently, intermetallics are easily formed and highly visible in zirconium and its alloys. Many researchers believe that the corrosion resistance of zirconium and its alloys depends strongly on the distribution and morphology of these intermetallics. Corrosion problems, such as nodular corrosion and intergranular corrosion, are often associated with intermetallics.
Numerous papers have been published concerning the role of intermetallics in nodular corrosion of Zircaloys. Several mechanisms have been proposed for nodule initiation and growth. They include one or more of the following factors: local solute depletion, electrochemical effects, oxide ductility, electronic and ionic conductivities of the surface oxide, induced stresses, and oxide structure transformation.
However, very limited studies have been directly done on the corrosion properties of these intermetallics. Therefore six intermetallics (Zr2Fe, Zr3Fe4Cr2, Zr10Fe3Ni2, Zr4Sn, ZrCr2, and 3Zr2Ni) were prepared for corrosion and electrochemical tests. These intermetallics were chosen since tin, iron, chromium, and nickel are the principal alloying elements in Zircaloys, and the selected intermetallics have been identified in the alloy matrix. In addition to these intermetallics, Zircaloy-2, Zircaloy-4, and crystal-bar zirconium were also included in this study.
Corrosion and electrochemical tests on selected materials at both ambient and elevated temperatures were performed at Teledyne Wah Chang Albany and at Siemens AG-KWU Group. Selected materials were characterized using SEM/EDX examinations, potential measurements and autoclave tests. From this information the role(s) of intermetallics on corrosion resistance in water and steam are discussed. A new electrochemical-mechanical-passivity (EMP) model is offered to explain observed oxidation of Zircaloy-2 and Zircaloy-4.
Amorphization of Precipitates in Zircaloy under Neutron and Charged-Particle Irradiation
Authors: Motta AT , Lefebvre F , Lemaignan C 
Published: March 2009

The crystalline-amorphous transformation of the intermetallic precipitates Zr(Cr,Fe)2 and Zr2(Ni,Fe) in Zircaloy under charged-particle and neutron irradiation is studied.
In the first section, the experimental results in the literature are reviewed for the three types of irradiation: neutron, electron, and ion. It is found that the dose to amorphization in all three types of irradiation exhibits roughly the same exponential dependence with temperature but that there are important differences. The critical temperatures, above which amorphization is not practically attainable, are different for each type of irradiation, indicating the presence of different damage accumulation and annealing mechanisms in each case. Further evidence of this are the different amorphization morphologies observed under neutron and electron irradiation, and the shift in the relative susceptibility to amorphization between the two types of precipitate under high (neutron and ion) and low (electron and ion) temperature irradiation.
In the next section, the theoretical models for amorphization are reviewed and applied to the problem in an effort to obtain a coherent picture of amorphization induced by all types of irradiation in the precipitate/zirconium system. Amorphization mechanisms are proposed for each type of irradiation, based on the experimental results.
A brief conclusion indicates that different mechanisms are operative for amorphization induced by each type of irradiation and points out future areas that in our view deserve further investigation.
The Corrosion of Zircaloy-4 Fuel Cladding in Pressurized Water Reactors
Authors: Van Swam LFP , Shann SH 
Published: March 2009

The effects of thermo-mechanical processing of cladding on the corrosion of Zircaloy-4 in commercial PWRs have been investigated. Visual observations and nondestructive measurements at poolside, augmented by observations in the hot cell, indicate that the initial black oxide transforms into a grey or tan and later white oxide layer at a thickness of 10 to 15 μm independent of the thermal processing history of the tubing. At an oxide layer thickness of 60 to 80 μm, the oxide may spall depending somewhat on the particular oxide morphology formed and possibly on the frequency of power and temperature changes of the fuel rods. Because spalling of oxide lowers the metal-to-oxide interface temperature of fuel rods, it reduces the corrosion rate and is beneficial from that point of view.
To determine the effect of thermo-mechanicai processing on in-reactor corrosion of Zircaloy-4, oxide thickness measurements at poolside and in the hot cell have been analyzed with the MATPRO corrosion model. A calibrated corrosion parameter in this model provides a measure of the corrosion susceptibility of the Zircaloy-4 cladding. It was found necessary to modify the MATPRO equations with a burnup dependent term to obtain a near constant value of the corrosion parameter over a burnup range of approximately 10 to 45 MWd/kgU. Different calculational tests were performed to confirm that the modified model accurately predicts the corrosion behavior of fuel rods.
For Zircaloy-4 cladding with a chemical composition near the mid-range of the ASTM specification, it is shown that the in-reactor corrosion performance can be correlated with the thermo-mechanical treatment of the cladding. The evaluation of the in-reactor corrosion data indicates that the corrosion performance of Zircaloy-4 cladding is improved by longer and/or higher temperature anneals in the alpha range after the material has been beta quenched. The best correlation between corrosion performance and thermo-mechanical treatment is obtained with the second order cumulative annealing parameter. This parameter is a measure of the size of intermetallic precipitates of Zr, Fe, and Cr in Zircaloy-4. However, a causal relationship between Zr (Cr, Fe)2 precipitate size and corrosion behavior has not been proven.
The Influence of Various Polymeric Materials on the Physical Properties of a Cementitious Patching Compound
Authors: Bright RP , Mraz TJ , Vassallo JC 
Published: March 2009

A series of polymer modified cementitious patches were formulated using a variety of liquid latex and redispersible powder modifiers. Properties evaluated included compressive, flexural and tensile strength, water resistance, abrasion resistance and adhesive strength. Formulations were evaluated at 5%, 10% and 20% polymer loading with the water level adjusted for a constant flow. A second series of experiments were carried out at 10% polymer loading at a constant water level.
The results of the study showed that there was a strong relationship between the water/cement ratio and the overall properties of the formulation. In the experiments with water/cement ratio adjusted to achieve a constant flow, the liquid emulsion that possessed a high degree of water reducing capability achieved the highest strength and water resistance. However, in the experiments with a constant water level, the redispersible powdered emulsions now had at least equivalent properties to the liquid polymers.
These results showed that it is possible to formulate a high performance one component patching and repair mortar using redispersible powder emulsions.
Effects of Latex Modification on the Failure Mechanism and Engineering Properties of Concrete
Authors: Soroushian P , Tlili A 
Published: March 2009

Effects of styrene-butadiene latex modification on the failure mechanism, mechanical, physical, and durability characteristics of concrete materials were studied.
Microscopic investigations were performed on concrete cylinders pre-loaded to different compressive stress levels in order to study the process of failure in concrete under increasing stress levels as influenced by latex modification. These results were indicative of the effectiveness of latex in controlling the initiation and growth of microcracks under load.
Test results on the impact resistance and flexural strength and toughness of concrete were used to quantify and statistically confirm the positive effects of latex modification on various aspects of the mechanical properties of concrete.
Durability studies showed that latex modification imparts significant improvements to the scaling resistance and impermeability characteristics of concrete.
Latex modification was also observed to substantially reduce the water absorption capacity of concrete. The effects of latex on free drying shrinkage strains and bulk specific gravity of concrete were not statistically significant.
Alpine Skiing Injuries in Children
Authors: Ekeland A , Nordsletten L , Lystad H , Holtmoen Å 
Published: March 2009

The skiing injuries in 59 children under age 15 were recorded in four Norwegian ski resorts during the winter of 1985/1986 and compared with a control population of 63 uninjured children of the same age group.
The most common injury sites were the lower leg (24%), knee (20%), and head (14%). Only 43% of the bindings for injured children under ten released during the accident, compared with 73% for injured children 10 to 14 years of age. In accordance with this, skiers under ten were more than twice as prone to lower extremity equipment related (LEER) injuries as children in the older age group. Fracture of the lower leg was the most serious of the LEER injuries, and accounted for 21% of the injuries in the youngest children and 10 percent in the age group 10 to 14 years. In contrast 18% of the older children suffered head injuries compared to only 5% in the younger children.
Beginners had an injury risk nine times the average, whereas intermediate skiers were underrepresented among the injured skiers. A skiing experience of three or more seasons reduced the injury risk while skiing. Nine percent of the injuries occurred during powder skiing, whereas 26% of the injured population and 46% of the uninjured population spent some time powder skiing the current day.
In conclusion, being a beginner is the highest injury risk factor in skiing.
Influence of Ski Boot Construction on Knee Load—A Biomechanical Investigation on Safety and Performance Aspects of Ski Boots
Authors: Schaff PS , Hauser W 
Published: March 2009

In contrast to the drop in the incidence of fractures of the lower leg that has been observed in recent years, the incidence of knee injuries has not decreased in skiing. There has even been a relative increase of severe knee lesions and isolated ACL ruptures, prompting us to conduct a comprehensive study of this phenomena.
The goal of the study was to develop a new measuring device for alpine skiing research by combining motion analysis, pressure and force measurement, comprehensive examine the forward/backward movement in ski boots in the lab and by means of telemetry on the slope and to come up with a proposal for a new safety concept to reduce the high number of knee injuries in alpine skiing in the future.
The first study was devoted to the forward movement in ski boots. Studying nine beginners and eight experts we found a 20% (sign. 0.05) lower forward lean capability of the beginner group in the same boot.
A randomized study with cross over design conducted on the slope, where we equipped 16 skiers with either soft or stiff boots for the duration of five ski days, revealed the learning behavior and forward position on the slope depending on the boot. The pupils became definitely less adept at learning if they were required to wear stiff ski boots and showed a significant lower forward flex angle. A skiing style in backward lean position was adopted and supported by the fixed backward spoiler.
In order to quantify the influence of the backward spoiler a special ski boot was constructed allowing the rear spoiler to give way at a variable, defined stiffness and register the angular displacement and horizontal force Fh. The results on ten male subjects showed most clearly that even a medium rear spoiler resistance will significantly reduce the peak force values by a factor of 5.5. The deceleration at the knee joint level is significantly higher (factor 1.6) in case of a rigid spoiler. The lab tests could be confirmed on the slope (significant reduction of max. force by factor 8). It also proved that normal skiing can be performed in such a boot without limitations.
In consideration of our results it is concluded that the principle of safety bindings must definitely apply in future in equal measure also to the ski boot. As a proposal for future safety concepts, we developed a safety ski boot, that allowed for the first time the rear part to open and give way after a certain amount of force (adjustable preload). The backward release bindings, which can often produce dangerous malfunctions if a strong force acts on them for a short while, and which were therefore only very reluctantly if all accepted by skiers, could thus be complemented by a safety system in the boots.
In all probability this would be a contributing factor to reducing the high incidence of knee injuries in skiing.
Strains Within the Anterior Cruciate and Medial Collateral Ligaments of the Knee at Loads Causing Failure
Authors: Berns GS , Hull ML , Patterson HA 
Published: March 2009

The contributions of this paper are twofold. One is measurement of loads and corresponding strains at failure in both the anterior cruciate (ACL) and medial collateral (MCL) ligaments of the knee, the two ligaments most commonly injured. To make these measurements, a five degree-of-freedom automated system was used to apply either a single load or a combination of two loads at flexion angles ranging from 0° to 45°. Approximately half of the specimens were loaded to fail the ACL and half the MCL. An anterior force consistently failed the ACL while a valgus moment and/or an external axial moment failed the MCL. Despite this consistency, there was wide variation in failure loads between specimens with more than a twofold difference in load levels. Also, there was a large variation in ligament strain at failure with a mean value of 6.7% and a coefficient of variation of 0.64.
The second contribution of this paper is the development and testing of empirical models to predict ligament failure. To provide data for these models, prior to the load-to-failure tests of the knee specimens, the load application system was used to apply sub-injury level loads corresponding to varus/valgus moments, axial moments, medial/lateral forces, anterior/posterior forces, and compressive force at flexion angles of 0°, 15°, and 30° for single loads and 0° and 30° for combination loads. Regression analysis was performed to determine empirical equations relating strain to both load and flexion angle. The ability to extrapolate these models to predict strain measured in the load-to-failure tests was evaluated. In general, the empirical models did not accurately predict strain at injurious load levels. The inability to make an accurate prediction was traced to the conservative sub-injury load levels used to develop the empirical models.
Skiing Forces and Moments at the Knee and Boot Top: Boot Stiffness Effects and Modeling
Authors: Yee AG , Mote CD 
Published: March 2009

The goals of this study are (1) to quantify the contribution of boot stiffness to the maximum forces and moments predicted at the boot top and knee, (2) to identify generalized regression models predicting the moment components at the boot top and knee for a skiing population, and (3) to quantify the contribution of inertial forces to the forces and moments predicted at the boot top and knee. Six subjects skiing a slalom course alternated test ski runs with lowest boot stiffness and highest boot stiffness settings in a boot with adjustable stiffness. Average (over all subjects and test runs) maximum ankle flexion is significantly greater (P = 0.005) by 11.5 degrees for the soft boot compared to the stiff boot. Average maximum compression force along the tibia is significantly smaller (P = 0.024) by 178N for the soft boot runs compared to the stiff boot runs. No other maximum force or moment component at the boot top and knee is significantly different between soft and stiff boot ski runs. Bending moments at boot top and knee are not clearly related to ankle flexion near neutral boot flexion (20 deg). Maximum bending moments at the boot top do not necessarily occur at maximum ankle flexion.
Generalized regression models predicting moments at the boot top and knee are developed for the subject population, using regression coefficients from individual ski runs normalized by subject height and weight. For the soft boot setting, average regression model correlation coefficients for A-P bending at the boot top, varus-valgus moment at the knee, and torsional moment along the tibia are 0.980, 0.916, and 0.867, respectively. Corresponding values for the stiff boot setting are 0.979, 0.889, and 0.882.