bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Biological Risk Assessment Approach to Establishing Water Quality-Based Effluent Limits
Authors: Fava JA , Kapp RM , Gift JJ , Flynn CR , Del Pup JA 
Published: March 2009

Once water quality criteria are derived by states for a designated use of a particular water body and approved by the U.S. Environmental Protection Agency, they become enforceable in-stream water quality standards. On rivers, these standards are usually applied to a designated low stream flow to establish water quality-based effluent limits. The design stream flow used most often is the Q7–10, the lowest 7-consecutive-day average flow that is expected to occur once in 10 years. By definition, the Q7–10 is generally exceeded in approximately 99 percent of the historical record. Therefore, setting effluent limits to continuously meet the in-stream standards designed for infrequent low flow periods, regardless of the actual flow conditions, adds a margin of safety to that already provided by the water quality standard.
The objective of this effort is to evaluate the design-stream-flow concept and the general relationships between water quality standards and effluent limits. An approach is presented to estimate the relative biological risks involved with applying instream standards to alternative stream flows. As an example, a predictive assessment of Pennsylvania's cyanide standard for the protection of warmwater fisheries was evaluated, using the lower Monongahela River as a model. Requirements for this assessment included hydrological, biological, and water quality data for the Monongahela River and an evaluation of the toxicological literature on cyanide.
The results of this assessment suggest that in setting standards for cyanide, the Q7–10 design flow needs to be employed only when the most biologically sensitive portion of the year corresponds with periods of potential low flow. At other times of the year, design flows greater than the Q7–10 can be used in standard setting. These preliminary findings provide a technically defensible site-specific basis for the dynamic application of water quality standards to more than one design stream flow. Such an approach can be developed by states to protect the most sensitive life-history events of aquatic species occurring during historically low-flow periods while still providing an equivalent degree of protection to the aquatic community during the remaining major periods of the year.
Laboratory Machine to Evaluate the Resistance of Tire Cords (Textile or Steel) to Tensile Fatigue or Compressive Fatigue or Both
Authors: Canevari C , Lala AG 
Published: March 2009

A device for measuring the fatigue resistance of tire reinforcing materials at pure tensile or compressive strain is described.
If a pure bending moment is applied to a specimen like the complex beam used in the Simoni-Canevari “bending dynamometer” the specimen deforms like an arc of a circle and will be subjected to pure tensile or compressive stresses according to the direction of the bending. After a mathematical study had shown the possibility of the construction, we thought of building a machine capable of bending this kind of specimen cyclically as an arc of a circle. With this machine we achieved compression or tension or both in cycles at different stress levels (both as regards the average value and range) by changing the length of the connecting rod and the crank.
The first results of the study of steel cord fatigue made on this device were related to belt fatigue performance of car tires. We have found: (a) on the tire, the indoor fatigue life measured at different lateral forces followed a trend that can be described by the curve in Fig. 1; (b) on the specimen, by increasing the strain on the cord, its life decreased with a similar law; (c) on the specimen, by appling dissymmetrical strains at equal total strain we obtained longer lives, with different behaviors if the mean strain were on the tensile side or on the compressive side; and (d) the visual aspects of the failures obtained with the machine were the same as those obtained in the tires tested on the road.
Prediction Methods for Fatigue Crack Growth in Aircraft Material
Authors: Schijve J 
Published: March 2009

In the first part of the paper a survey is given of relevant knowledge on fatigue crack growth and qualitative and quantitative understanding of predictions. Aspects of cycle-by-cycle predictions and characteristic K prediction methods are discussed. In the second part recent work on prediction problems is reported. This includes (a) crack growth under flight-simulation loading with crack closure measurements, (b) predictions for flight-simulation loading based on a constant crack opening stress level, and (c) crack growth under pure random loading with different Srms-values, two irregularities and two crest factors.
The random load tests were also carried out to explore the usefulness of Krms. The paper is concluded with some indications for future research and a number of conclusions.
Tensile Cracks in Creeping Solids
Authors: Riedel H , Rice JR 
Published: March 2009

The aim of the paper is to answer the question: which loading parameter determines the stress and strain fields near a crack tip, and thereby the growth of the crack, under creep conditions? As candidates for relevant loading parameters, the stress intensity factor KI, the path-independent integral C*, and the net section stress σnet have been proposed in the literature. The answer, which is attempted in this paper, is based on the time-dependent stress analysis of a stationary crack in Mode I tension. The material behavior is modeled as elastic-nonlinear viscous, where the nonlinear term describes power law creep. At the time t = 0, load is applied to the cracked specimen, and in the first instant the stress distribution is elastic. Subsequently, creep deformation relaxes the initial stress concentration at the crack tip, and creep strains develop rapidly near the crack tip. These processes may be analytically described by self-similar solutions for short times t.
An important result of the analysis is that small-scale yielding may be defined. In creep problems, this means that elastic strains dominate almost everywhere except in a small “creep zone” which grows around the crack tip. If crack growth ensues while the creep zone is still small compared with the crack length and the specimen size, the stress intensity factor governs crack growth behavior.
If, however, the calculated creep zone becomes larger than the specimen size, the stresses become finally time-independent and the elastic strain rates can be neglected. In this limiting case, the stress field is the same as in the fully-plastic limit of power law hardening plasticity that has been treated in the literature. The loading parameter that determines the near tip fields uniquely is then the path-independent integral C*.
It should be emphasized that KI and C* characterize opposite limiting cases. Which case applies in a given situation can be decided by comparing the creep zone size with the specimen size and the crack length. Criteria for small-scale yielding are worked out in several alternative forms. Besides several methods of estimating the creep zone size, a convenient expression for a characteristic time is derived also, which characterizes the transition from small-scale yielding to extensive creep of the whole specimen.
A Critical Examination of a Numerical Fracture Dynamic Code
Authors: Hodulak L , Kobayashi AS , Emery AF 
Published: March 2009

After upgrading the energy dissipation algorithm, numerical experiments were conducted to assess the reliability of the explicit dynamic finite element code, HCRACK. Two dynamic fracture specimens (that is, the wedge-loaded rectangular double cantilever beam (RDCB) specimen and the wedge-loaded tapered double cantilever beam (TDCB) specimen), which were studied experimentally by Kalthoff, Beinert, and Winkler, were then analyzed with this updated fracture dynamic code. Using the experimentally determined dynamic fracture toughness, KID, versus crack velocity, ˙a, relation, the RDCB specimen was analyzed first by the “propagation method” where good agreements between calculated and measured KID versus a relations were observed. The calculated a versus time, t, relation was then used as input data in the “generation method” where the resultant KID were virtually identical to those obtained in the propagation method. Error analyses of the generation method also were made first by using the experimentally determined a versus t relation and secondly by artificially perturbing this relation.
A TDCB specimen was then analyzed with both the propagation and generation methods by using the KID versus ˙a relation established for this specimen and the measured a versus t relation, respectively. The computed KID obtained by both methods were in good agreement with the experimental results, showing that either approach can be used in analyzing fracture.
Temperature Dependence of the Fracture Toughness and the Cleavage Fracture Strength of a Pressure Vessel Steel
Authors: Kotilainen H 
Published: March 2009

A new model for the temperature dependence of the fracture toughness has been sought. It is based on the yielding processes at the crack tip, which are thought to be competitive with fracture. Using this method a good correlation between measured and calculated values of fracture toughness has been found for a Cr-Mo-V pressure vessel steel as well as for A533B. It has been thought that the application of this method can reduce the number of surveillance specimens in nuclear reactors.
A method for the determination of the cleavage fracture strength has been proposed. It can be measured either with low temperature tensile tests or with slow bend tests of Charpy V-notch specimens.
On the Equivalence Between Semi-Empirical Fracture Analyses and R-Curves
Authors: Orange TW 
Published: March 2009

This paper examines the relationship between several semi-empirical fracture analyses (SEFA) and the R-curve concept of fracture mechanics. The conditions for equivalence between a SEFA and an R-curve are derived. A hypothetical (imaginary) material is employed to study the relationship analytically. Equivalent R-curves (ERC) are developed for real materials using data from the literature.
For each SEFA there is an ERC whose magnitude and shape are determined by the SEFA formulation and its empirical parameters. If the R-curve is indeed unique, then the various empirical parameters cannot be constant, and vice versa. However, for one SEFA the differences are small enough that they may be within the range of normal data scatter for real materials.
Application of Hydrostatic Extrusion to Fabrication of Zircaloy Tubing
Authors: Nagai N , Kakuma T , Matsushita T , Kimpara M 
Published: March 2009

Preliminary experiments in the extrusion of Zircaloy tubing using both cold and hot hydrostatic extrusion processes were carried out.
In the cold hydrostatic extrusion, a maximum extrusion ratio of five could be obtained, but it should be limited to a maximum of three to prevent the occurrence of galling. When the cold hydrostatic extrusion process was applied to the final pass of cold reducing, the properties of the obtained tubes were nearly identical to those of the current boiling water reactor cladding tubes in spite of the difference of the crystallographic texture of the tubes.
Application of the newly developed hot hydrostatic extrusion process to the extrusion of tube shells resulted in an increase of the extrusion ratio to three times that of the conventional direct extrusion. The tubing processed from hydrostatically extruded tube shells at the higher extrusion ratios showed higher strength and lower ductility than those of lower extrusion ratios in the tension tests. In the case of the burst tests, however, the ductility was higher in the tubes processed from the tube shells of the higher extrusion ratios.
Long-Term Test Results of Promising New Zirconium Alloys
Authors: Castaldelli L , Fizzotti C , Lunde L 
Published: March 2009

A series of new alloys has been long-term tested in different reactors and environments together with other alloys, including Zr-2.5Nb, Ozhennite 0.5, and Zircaloy-2. One of the new alloys with the composition of Zr-1Nb-1Sn-0.5Fe has significantly improved properties.
The zirconium-niobium alloys have corrosion properties similar to Zircaloy-2 in the temperature range 240 to 400°C while they are better at 450°C and above. Conditions leading to nodular corrosion in Zircaloy-2 did not produce nodular attack on the Zr-1Nb-1Sn-0.5Fe alloy, or on Zr-2.5Nb. The niobium-containing alloys fail to suffer intergranular cracking in iodine-methanol solution even when stressed to 80 percent of their yield strength for more than 60 days. The other alloys failed at 30 percent of yield strength in a few hours. Preliminary iodine-argon iodine-pressurized burst tests indicate some improvement for the Zr-1Nb-1Sn-0.5Fe alloy compared with Zircaloy-2 with a five to ten times increase in time to failure for the same stress level.
Elongation was markedly reduced by irradiation in all the alloys. Uniform elongations of about 1 percent were observed in the 2.5Nb alloy while the highest uniform elongation of 2 to 3 percent was shown by the Zr-1Nb-1Sn-0.5Fe alloy.
Effects of Temperature and Pressure on the In-Reactor Creepdown of Zircaloy Fuel Cladding
Authors: Hobson DO , Thoms KR , Dodd CV , van der Kaa T 
Published: March 2009

Descriptions and results for seven of the eight in-reactor creepdown tests of Zircaloy fuel cladding, which were part of a joint program between the U.S. Nuclear Regulatory Commission and Energieonderzoek Centrum Nederland, are presented. These tests were conducted to study the behavior of Zircaloy fuel cladding under conditions that approximate those found in an operating pressurized-water power reactor.
Radial surface displacement values as functions of time, average diametral-circumferential strain as a function of time, and isochronal deformation surfaces are presented. Tests were conducted at 343°C with external pressures from 13.3 to 18.7 MPa. Three of the specimens were subjected to stress reversal during their test runs, wherein they were pressurized internally from 3.5 to 6.9 MPa. Fast flux [E &gt; 1.0 MeV (0.2 pJ)] ranged from 3.8 × 1017 to 5.0 × 1017 neutrons (n)/(m2·2). Maximum fluence was approximately 7 × 1025 n/m2.
The most important conclusion to be drawn from this study involves the deformation of the cladding during testing. Contrary to similar tests conducted out-of-reactor, the in-reactor specimens did not deform uniformly, that is, by diametral contraction and smooth ovalization. Rather, the deformation surfaces were nonuniform with hills and valleys being formed at irregular intervals. This implies that conventional concepts of creep rate and simplified modeling procedures will not work for predicting cladding behavior. Sufficient data have been generated in this program to supply modelers with detailed descriptions of the cladding surface shapes from which new interpretations can be derived to predict cladding behavior.
High-Strength, Creep-Resistant Excel Pressure Tubes
Authors: Cheadle BA , Holt RA , Fidleris V , Causey AR , Urbanic VF 
Published: March 2009

Pressure tubes for CANada Deuterium Uranium Pressurized Heavy Water reactors are made from Zr-2.5Nb by extruding preheated hollow billets into tubes that are cold-worked 30 percent to size. The fabrication process produces fine elongated α-grains with a high dislocation density which makes a large contribution to the tensile strength of the tubes but increases in-reactor creep and growth rates.
The alloy Excel (Zr-3.5Sn-0.8Mo-0.8Nb) is stronger and more creep resistant than Zr-2.5Nb and is being developed as a pressure tube material. Tubes have been fabricated that are as strong as the Zr-2.5Nb tubes but they have more equiaxed α-grains with much lower dislocation densities. The tubes corrode faster than the Zr-2.5Nb tubes and will require 0.1 mm more corrosion allowance on the 4.1-mm-thick walls. However, their in-service axial elongation and diametral expansion due to irradiation creep and growth will be 70 percent less than the Zr-2.5Nb tubes.
Zircaloy-4 Cladding Deformation During Power Reactor Irradiation
Authors: Franklin DG 
Published: March 2009

The four primary Zircaloy fuel cladding deformation phenomena—axial elongation, circumferential creep, ovalization, and ridging—have been investigated for fuel irradiated in four modern pressurized water reactors. The axial elongation of fueled and nonfueled rods is examined by a regression fit for dependence on fluence, clad texture, yield stress, applied stress and, for fuel rods, fuel pellet length to diameter ratio. For fueled rods, only fluence and stress are found to be important, although the range of texture data is small. For nonfueled rods, the texture is found to influence elongation.
The circumferential creep strain data from nonfueled rods are also analyzed by a regfression analysis to estimate the effects of time, flux, applied stress, temperature, yield stress, and texture. Time and flux have weaker than linear influence on strain, while the stress has a stronger than linear influence. The strain rate is almost athermal. The creep strain clearly increases with preirradiation yield strength. However, the primary difference is between recrystallized and stress-relief-annealed cladding with the degree of retained cold work having less effect. The creep rate clearly decreases with an increase in the angle between the basal poles and the radial direction. The effects of carbon content and grain size are also discussed.
Ovalization of fueled and nonfueled rods is observed although analysis is difficult. The sensitivity of post-irradiation ovality to initial ovality and the relatively large uncertainty in initial ovality have precluded effective regression analysis although the general effects of applied stress, yield stress, and initial ovality are given. Clad ridging develops in fueled rods, usually in a time period between one and two reactor cycles and almost always after three cycles. However, the maximum ridge height occurs before the end of two reactor cycles.
An Experimental Study of the Deformation of Zircaloy PWR Fuel Rod Cladding Under Mainly Convective Cooling
Authors: Hindle ED , Mann CA 
Published: March 2009

In a loss-of-coolant accident (LOCA) the temperature of the cladding of some fuel rods may rise to levels [650 to 810°C (1202 to 1490°F)] where the ductility of Zircaloy is high (∼80 percent). The net outward pressure which will obtain if the coolant pressure falls to a small fraction of its normal working value produces stresses in the cladding which can result in large strain through secondary creep. An earlier study of the deformation of specimens of pressurized water reactor (PWR) Zircaloy cladding tubing 450 mm (18 in.) long under internal pressure had shown that strains of over 50 percent could be produced over considerable lengths (greater than 20 tube diameters). Extended deformation of this sort might be unacceptable if it occurred in a fuel assembly. The previous tests had been carried out under conditions of uniform radiative heat loss, and the work reported here extends the study to conditions of mainly convective heat loss, believed to be more representative of a fuel assembly following a loss of coolant.
Zircaloy-4 cladding specimens 450 mm (18 in.) long were filled with alumina pellets and tested at temperatures between 630 and 915°C (1166 and 1679°F) in flowing steam at atmospheric pressure. Internal test pressures were in the range 0.69 to 11.0 MPa (100 to 1600 lb/in.2). Maximum strains were observed of the same magnitude as those seen in the previous tests, but the shape of the deformation differed; in these tests the deformation progressively increased in the direction of the stream flow.
The length of cladding strained 33 percent or more was greatest (about 20 times the original diameter) when the initial pressure was 1.38 ± 0.17 MPa (200 ± 25 lb/in.2). It is though that this results from oxidation strengthening of the surface layers acting as an additional mechanism for stabilizing the deformation or partial superplastic deformation, or both. For adjacent rods in a fuel assembly not to touch at any temperature, the pressure would have to be less than about 1 MPa (145 lb/in.2). These results are compared with those from multirod tests elsewhere, and it is suggested that heat transfer has a dominant effect in determining deformation. The implications for the behavior of fuel elements in a LOCA are outlined.
Effect of Hydrogen on the Oxygen Embrittlement of Beta-Quenched Zircaloy-4 Fuel Cladding
Authors: Seiffert SL 
Published: March 2009

Zircaloy cladding embrittlement was evaluated from data derived from the postirradiation examination of 47 light-water reactor type fuel rods irradiated under postulated accident conditions. The previously irradiated and unirradiated rods were tested in 15 separate in-pile experiments in the Power Burst Facility reactor at the Idaho National Engineering Laboratory as part of the Thermal Fuels Behavior Program. Film boiling conditions ranged in duration from a few seconds to about 15 min, with cladding peak temperatures ranging from 1315 to ≥ 2100 K in the most severely oxidized Zircaloy. Quenching from film boiling temperatures through the β → α′ phase transformation was at rates of about 50 to 100 K/s, depending on test conditions.
The Zircaloy-4 cladding showed rapid oxygenation of the β-phase Zircaloy and hydriding in excess of the pretest characterization. Cladding embrittlement in the intact rods was consistent with previously established oxygen embrittlement criteria. Fuel rods operated with a cladding defect were embrittled to a greater extent than intact rods oxidized under similar conditions. A modified background prior β-phase and precipitation of rim-α was typically observed in the failure region of breached rods. The fracture resistance of breached rods appears to be related to enhanced hydrogen absorption and its influence on both the β-phase transformation and the α′-morphology during rapid (∼ 100 K/s) quenching.
A Comparison of the High-Temperature Oxidation Behavior of Zircaloy-4 and Pure Zirconium
Authors: Pawel RE , Campbell JJ 
Published: March 2009

Oxidation rate data for Zircaloy-4 in steam under isothermal conditions in the temperature range 1000 to 1500°C indicate that the kinetics of layer growth and oxygen consumption can be described by virtually ideal parabolic behavior. Thus, the growth of the two product phases, oxide and oxygen-stabilized α, is presumed to be controlled by diffusion processes leading to uniform layer thickening. We have measured the oxidation rate of pure, arc-melted, crystal-bar zirconium under similar conditions and have found differences in the reaction characteristics compared with Zircaloy-4. At temperatures from 1098 to 1416°C, while parabolic kinetics are still observed, the growth rates for both phases are measurably different. Our analysis of these data in terms of a multilayer diffusion model suggests that the effective chemical diffusion coefficient for oxygen in the oxide phase has been altered. Despite the kinetic differences, however, the analysis also concludes that the diffusion coefficient of oxygen in the α layers is identical, a finding consistent with the results of independent measurements.
In addition to the decreased oxygen diffusivity in the oxide phase on pure zirconium compared with that on Zircaloy-4, a higher activation energy was also observed, implying that some mechanistic differences exist. Without additional information, it is not possible to attribute these differences to changes in the oxide defect structure resulting from alloying. However, significant morphological and grain size differences exist in the columnar oxide growing on the two materials, and it is possible that the relative contributions to oxide growth from short-circuit diffusion differ in the two oxides.