bluuebunny/crossref_metadata_2025_split huggingface dataset:
New Solvent Extraction Process for Zirconium and Hafnium
Authors: Takahashi M , Miyazaki H , Katoh Y 
Published: December 2008

The authors' company developed a new solvent extraction process for zirconium and hafnium separation, and started production of zirconium sponge by this new process in September 1979.
The process utilizes selective extraction of zirconium oxysulfate using high-molecular alkyl amine, and has the following advantages:
1. This extraction system has a separation factor as high as 10 to 20 for zirconium and hafnium in the range of suitable acid concentration.
2. In the scrubbing section, removal of all the hafnium that coexists with zirconium in the organic solvent can be effectively accomplished by using scrubbing solution containing hafnium-free zirconium sulfate. Consequently, hafnium in the zirconium sponge obtained is reduced to less than 50 ppm.
3. The extractant undergoes no chemical changes but is very stable for a long period. In particular, its solubility in water is small, about 20 ppm maximum, posing no environmental pollution problems such as are often caused by other process raffinates.
At the present time, the zirconium and hafnium separation operation is very stable, and zirconium sponge made by this process can be applied satisfactorily to nuclear reactors.
Electron-Beam Remelting of Zircaloys
Authors: Mitchell A , Brown R 
Published: December 2008

We have constructed and operated an electron-beam (EB) melting furnace using a 15-kW von Ardenne electron gun. The evaporation of tin from metling Zircaloys and the dissolution of nitride inclusions in melting Zircaloys have been studied.
We conclude that Zircaloys can be melted successfully in a 500-mm ingot diameter EB furnace at melting rates between 200 and 500 kg/h without special composition precautions with respect to tin. This configuration will also dissolve zirconium nitride precipitates successfully.
Influence of Metallurgical Condition on the In-Reactor Dimensional Changes of Zircaloy Fuel Rods
Authors: Garde AM , Smerd PG , Garzarolli F , Manzel R 
Published: December 2008

Microstructure strongly affects the in-reactor creep and growth behavior of Zircaloy. The observed influence of microstructure on the in-reactor creep behavior can be opposite to that found ex-reactor. Fully annealed Zircaloy exhibits less in-reactor growth strains than stress-relief-annealed Zircaloy.
Two approaches to estimate the effect of microstructural variation on the in-reactor creep and growth behavior are discussed. These evaluations are based on diametral and axial strain data, for exposures of up to 8 × 1021 neutrons/cm2 (E &gt; 0.82 MeV), obtained from tests conducted in the Obrigheim reactor (Germany) and in Calvert Cliffs I (United States). In the former tests the Zircaloy-4 cladding was manufactured by several vendors using different combinations of degree of cold work and final heat treatment while in the latter tests cladding of one type was used. All irradiated cladding had similar crystallographic textures.
The metallurgical condition of Zircaloy tubing is controlled in part by the degree of cold work prior to the final annealing treatment and by the annealing conditions. In one approach, the net effect of annealing time and temperature is empirically defined in terms of a “normalized annealing time.” A nonlinear relationship was obtained between the “normalized annealing time” and the in-reactor diametral and axial strains.
The other approach involves using the high-temperature yield strength as an effective reflection of the microstructure. The high-temperature yield strength of Zircaloy is routinely included in the Zircaloy tubing manufacturer's certifications and can be easily measured. There is a semilogarithmic relationship between the in-reactor diametral strain and the hot (673 K) yield strength of Zircaloy. The model is also useful in estimating the diametral strain variation within a lot if the within-lot yield strength variability is known. A similar correlation was obtained between the axial strain and the unirradiated yield strength. Although based on data from fuel rods of one design, the correlations are expected to be qualitatively applicable to fuel rods of different designs. Relationships between these empirical correlations and creep and growth mechanisms are discussed.
Irradiation Growth of Zircaloy (LWBR Development Program)
Authors: Willard HJ 
Published: December 2008

Irradiation growth of recrystallized annealed (RXA) Zircaloy is divided into four stages and a model is presented to account for each stage. Stage I is a short-time, low-strain transient caused by the accumulation of point defects, small interstitial loops, and vacancy clusters. Stage II is a quasi-steady-state region of relatively low strain rate during which the loops grow and intrinsic dislocations climb. Stage III is a transient during which the strain rate increases due to the production and motion of irradiation-induced dislocation lines. Stage IV is a high-strain-rate, steady-state region during which nonrecoverable strain is caused predominantly by glide of the irradiation-induced dislocations.
The proposed model is based on two new mechanisms: (1) direct production of an interstitial dislocation loop accompanied by a vacancy cluster in the primary damage event, and (2) production of dislocations due to the activation of Frank-Read sources by internal stresses caused by interaction of the loops with themselves and with intrinsic (cold work) dislocations. Nonconservative, recoverable strain is due to climb of all dislocations, whereas conservative, nonrecoverable strain is caused by glide of irradiation-induced and intrinsic dislocations under the action of the internal stress. The conservative strain follows a (1–3f) texture dependence.
The model provides a reasonable representation of growth behavior of longitudinally oriented RXA Zircaloy, the effect of texture and cold work on growth, and the temperature dependence of growth. Equations used to represent the model were solved in their transient forms at each time step of irradiation histories which permitted variations in flux and temperature. Calculations revealed that a nonlinear flux dependence can exist in growth behavior under various conditions of temperature and material structure and that this dependence can change as the irradiation history accumulates. Thus, the current practice of using fluence as the independent variable in data analysis and model development is questionable. The results of using the model to examine recent data obtained in the Experimental Breeder Reactor II at high temperatures and fast fluxes suggest that growth under these conditions is strongly sensitive to variations in flux and rather weakly dependent upon temperature.
Characterization of ZrO2 Films Formed In-Reactor and Ex-Reactor to Study the Factors Contributing to the In-Reactor Waterside Corrosion of Zircaloy
Authors: Stehle H , Garzarolli F , Garde AM , Smerd PG 
Published: December 2008

An examination has been conducted of irradiated oxides which were formed during the waterside corrosion of Zircaloy-clad fuel rods operating in several pressurized-water reactors (PWR's), in order to understand the corrosion behavior. The structural integrity of the oxide layer was found to be excellent. The thermal conductivity remained high for oxides up to 70 μm thick.
Scanning electron microscope (SEM) examinations revealed that the bulk of the oxide had a spherical, granular microstructure providing for interconnected porosity, mainly at the triple points. With the exception of the steam autoclaved specimens, a thin inner layer was detected close to the metal substrate; this inner layer had a microstructure which was difficult to resolve with the SEM. The in-reactor corrosion enhancement was greater for oxides which had a more pronounced granular appearance at the metal-oxide interface.
Post-irradiation corrosion testing in autoclaves indicated a pronounced memory effect only for those specimens which previously had a high in-reactor enhancement.
The analyses of potential impurities in the oxide gave no indication of a significant enrichment of any chemical species from the primary coolant water.
The modest in-reactor corrosion enhancement observed in the PWR environment may be partly due to irradiation accelerated recrystallization of the oxide, especially at the inner layer, and partly due to changes in the corrosive medium present in the porous outer section of the oxide.
Modeling of Zircaloy Stress-Corrosion Cracking: Texture Effects and Dry Storage Spent Fuel Behavior
Authors: Tasooji A , Einziger RE , Miller AK 
Published: December 2008

A phenomenological model has been developed for predicting iodine-induced stress-corrosion crack (SCC) initiation and growth in Zircaloy cladding. This model is capable of predicting various observed behaviors related to SCC.
A recently developed submodel for predicting the effect of texture on SCC has been incorporated into the original stress-corrosion crack initiation and growth (SCCIG) model. It utilizes basal pole figure data. This allows predictions of a number of observed phenomena on the effect of texture on SCC. In the process the model helps to explain why texture has different apparent effects on Zircaloy SCC depending on the test conditions.
The SCCIG model can also be used for predicting cladding SCC behavior under dry storage conditions. In this study the model has been used to predict the cladding SCC limiting temperature (SLT) for several specific fuel rod conditions.
Deformation and Failure of Zircaloy Fuel Sheaths Under LOCA Conditions
Authors: Sagat S , Sills HE , Walsworth JA 
Published: December 2008

A unified, microstructural creep law which simulates the transient creep deformation of Zircaloy at temperatures above 750 K has been used to follow the interaction of diffusional and dislocation creep with changes in material microstructure (grain size, recrystallization, phase fraction and anisotropy) under loss-of-coolant accident (LOCA) conditions. Comparison of a membrane sheath model using this creep law with a large number of tube tests (&gt;700) in an inert environment has demonstrated good predictive capability.
This model has been extended to cover other aspects affecting deformation and failure of CANDU (CANada Deuterium Uranium) fuel sheaths such as: nonuniform structure distribution resulting from temperature profiles along the sheath length, oxidation of the fuel sheaths, cracking of the oxidized layers and localized straining, large strain failure, and failure by beryllium-assisted cracking.
Elastic-Plastic Fracture Toughness Tests with Single-Edge Notched Bend Specimens
Authors: Anderson TL , McHenry HI , Dawes MG 
Published: December 2008

Fracture toughness tests have been performed on five geometries of single-edge notched bend (SENB) specimens machined from a 25.4-mm (1.0-in.) thick plate of ABS Grade EH36 steel, a normalized carbon-manganese steel. Critical values of the J integral and the crack-tip opening displacement (CTOD) were measured as a function of temperature. Test temperatures, which ranged from −196 to 25°C, covered the entire ductile-to-brittle transition range. On the upper shelf, critical values of J and CTOD at the onset of stable crack growth were insensitive to specimen geometry. However, in the ductile-to-brittle transition region, where fracture occurred by unstable cleavage, fracture toughness decreased with increasing specimen thickness and crack length. This effect of geometry on fracture toughness in the transition region is attributed to changes in cracktip region constraint with geometry.
Various aspects of the SENB fracture toughness test have been examined. Experimental results indicate that both J and CTOD can be accurately measured with a single clip gage. Work hardening caused the ratio of J to CTOD to increase with strain. The m factor, which relates J to CTOD and flow stress, was directly proportional to the notch constraint factor. The η factor, which is a dimensionless constant used to relate the J integral to energy absorbed by the specimen, was independent of crack length for SENB specimens of ABS EH36 steel with a/W ranging from 0.19 to 0.75. The rotational factor rp was not a strong function of temperature or specimen geometry in the material studied.
Subsurface Pollution Containment Using a Composite System Vertical Cutoff Barrier
Authors: Druback GW , Arlotta SV 
Published: December 2008

A new concept for constructing a vertical impermeable barrier to prevent the migration of polluted groundwater or leachate from a contaminated site or waste disposal area is presented. The composite system is a hybrid cutoff wall constructed with high density polyethylene (HDPE) and sand backfill and is installed using the slurry trench construction method. When installed, a very low permeability, composite, vertical barrier is established with unique engineering properties, including improved chemical resistance, leak detection, and groundwater migration control.
A full-scale construction test project of the system was performed at an existing sanitary landfill in New Jersey in the fall of 1982 to demonstrate the overall fabrication and construction procedures. The test project was conducted in three phases: (1) the excavation of a trench filled with the bentonite slurry mixture through the landfill waste; (2) the cutting and seaming of HDPE material to form an envelope; and (3) the placement of the envelope and subsequent backfilling with sand and water. The success of the operation under often difficult conditions proved that the theory and construction concept of the composite system barrier can be utilized to construct a cutoff wall. Useful information for future applications at contaminated sites was gained.
The Permeability of Clay to Acidic and Caustic Permeants
Authors: Lentz RW , Horst WD , Uppot JO 
Published: December 2008

Results of a laboratory study of the effects of acidic and caustic permeants upon the permeability of various fine-grained soils are reported. Triaxial falling head permeability tests were performed on specimens of kaolinite, kaolinite-bentonite mixture, and magnesium montmorillonite. Permeants used were hydrochloric acid with pH values of 1, 3, and 5 and water and sodium hydroxide with pH values of 9, 11, and 13. In no case for any of the clays or permeant pH did the permeability increase during the passage of six pore volumes of permeant, which indicates that no significant dissolution of clay minerals occurred. The only permeant that caused significant change in permeability was sodium hydroxide at a pH of 13, which caused a reduction in permeability of the magnesium montmorillonite by a factor of 13. This was found to be due to precipitation of magnesium hydroxide in the pores. Results are compared with findings reported by other researchers.
It is concluded that because of the wide variety of reactions possible between clays and permeant, future reports of permeability changes should give as much detail as possible about the chemistry and mineralogy of the soil studied. The equipment used and testing technique also have significant effects on reported test results and should be described in detail. Also, it is suggested that research is needed into possible reactions which could be induced within the soil pores to create favorable changes in permeability.
The Effect of Organic Fluids on Hydraulic Conductivity of Compacted Kaolinite
Authors: Acar YB , Hamidon A , Field SD , Scott L 
Published: December 2008

The effects of four organic fluids on hydraulic conductivity of compacted kaolinite are presented. Permeation fluids were 0.1 and 100% solutions of nitrobenzene, acetone, phenol, and benzene, which represent a wide range of dielectric constants. Full saturation hydraulic conductivities were obtained in flexible wall permeameters under continuous back pressure, at hydraulic gradients of less than 100 and effective stresses of 69 kPa (10 psi). Reference hydraulic conductivity values were determined with 0.01 N calcium sulfate (CaSO4) solution.
The effect of the testing scheme was evaluated by measuring the hydraulic conductivity of acetone in both a flexible wall permeameter at variable effective stresses and in a rigid wall permeameter. Dramatic hydraulic conductivity increases were observed in rigid wall permeameters. The results indicate that increases in the hydraulic conductivity measured in rigid wall permeameters can only be explained by side leakages due to shrinkage of the specimen.
All tests with chemicals at low concentrations resulted in slight decreases of hydraulic conductivity. Hydraulic conductivity with pure solutions slightly increased with acetone and phenol and significantly decreased with benzene and nitrobenzene. Diffusion through the cell membrane was found to be a considerable source of error in assessing the full strength of organic fluids. The direction of variations in the liquid limit and the free swell of kaolinite with organic fluids was observed to be inversely related to changes in absolute values of hydraulic conductivity at low effective stresses. These results together with fabric studies indicated that changes in hydraulic conductivity with organic fluids can be explained by the variations in the surface forces of interaction on clay particles affecting the flow characteristics.
Interactions Between Acidic Solutions and Clay Liners: Permeability and Neutralization
Authors: Peterson SR , Gee GW 
Published: December 2008

Liner failure, defined as an increase in liner permeability, was not found to be a problem when acidic uranium mill tailings solutions percolated through clay liner materials for periods extending up to three years. Liner materials taken from mill sites in Wyoming decreased in permeability with time in the laboratory columns when permeated with tailings solution. One clay liner decreased in permeability from one half to over two orders of magnitude, depending on the given clay sample and contacting solution. These decreases in permeability were attributed to pore plugging resulting from the precipitation of minerals and solids and to soil particle dispersion.
The clay liner material from Morton Ranch, Wyoming, exhibited a residual buffering capacity that was able to maintain column effluent pH values at higher levels than the influent pH values for extended time (in excess of 30 pore volumes). A likely cause for the elevated pH is the redissolution of iron and aluminum hydrous oxides. Redissolution of iron and aluminum hydrous oxides consumes hydrogen ions.
Soil-Cement Liners
Authors: Adaska WS 
Published: December 2008

For over 30 years soil-cement has been effectively used to line lakes, reservoirs, ditches, and irrigation ponds. More recently, wastewater treatment lagoons, sludge drying and ash settling ponds, and coal storage areas have been lined with soil-cement. In addition to its low permeability, soil-cement also provides a reliable method of slope protection.
Numerous laboratory permeability tests have been performed on various soil-cement mixtures. One study included the addition of lime and fly ash to the mixture. Research has been also conducted on shrinkage cracking in soil-cement and its effect on total seepage.
A large-scale field test to determine seepage through a stairstep constructed soil-cement facing was conducted by the Bureau of Reclamation at the Lubbock Regulating Reservoir in Texas. The study indicated the soil-cement to be quite impervious and that most of the seepage occurred through either shrinkage cracks or along the horizontal contact planes. It also showed an overall decrease in seepage with time.
The U.S. Environmental Protection Agency (EPA) has reported laboratory test results on the compatability of soil-cement to various hazardous and other industrial wastes. The tests concluded that exposure to acids such as from electroplating sludges and acidic steel-pickling wastes should be avoided; however, for toxic pesticide formations, oil refinery sludge, toxic pharmaceutical wastes, and rubber and plastic wastes, soil-cement should perform satisfactorily. For caustic petroleum sludges, compatability tests should be conducted on the specific combination of soil-cement and waste.
This paper will include basic information on soil-cement as a linear material and describe in detail the research work on permeability and compatability testing, which has been briefly mentioned. The design, construction, and performance of some unique soil-cement-lined projects will be also presented as well as information on a new composite soil-cement/synthetic membrane liner system that meets the latest U.S. EPA requirements for containing hazardous wastes.
Analytical Determination of Normal Contact Stresses for Arbitrary Geometries with Application to the Tire/Pavement Interaction Mechanism
Authors: Clapp TG , Kelley CT , Eberhardt AC 
Published: December 2008

A method for approximating the normal contact pressure distribution and the contact length associated with tire/pavement interaction has been developed using deformed tire geometry as a measured function of position. The mathematical development of the method is based on classic contact stress theory for contact between an elastic half plane and a rigid indenter. The unknown pressure distribution satisfies a linear integral equation and is approximated by an M-order polynomial with M + 1 unknown coefficients. The unknown coefficients are found by evaluation of both sides of the integral equation at M + 1 points, and the polynomial pressure distribution is plotted. The order, M, of the pressure distribution polynomial is sequentially increased until the pressure distribution stabilizes, completing the solution process. The contact length is approximated from sign changes in the pressure distribution caused by the geometric characteristics of the deformation curve for the tire not in contact with the pavement surface.
Polynomial approximations for the pressure distributions compare favorably with the analytical pressure distributions for arc-shaped and triangular indenters. The approximated contact lengths are within 10% of those measured experimentally. These results provide basic verification of the approximation method. The information available through this method is essential for the generation of realistic time-fluctuating force inputs into analytical vibration response models when predicting tire vibration response on various types of pavement surfaces.
Aquatic Macrophyton Sampling: An Overview
Authors: WM Dennis 
Published: December 2008

Aquatic macrophytes constitute an integral part of aquatic ecosystems, contributing to primary productivity, providing habitat for various organisms, and modulating water quality. Recent attention on the characterization and understanding of aquatic macrophyte communities within North America has primarily been the result of water-use problems caused by excessive infestations of “weedy” aquatic plant species.
Aquatic macrophyte communities have been sampled using such devices as oyster tongs and rakes, drag chains, various fixed-size quadrats, and complex hydraulically controlled pontoon-mounted mechanical biomass samplers. More recently, subsurface sampling techniques have evolved using scuba, and remote sensing techniques have been developed using various platforms from balloons to fixed-wing aircraft to satellites.
Sampling protocol for aquatic macrophyte studies should be designed to answer the specific question(s) at issue, applicable to the physical characteristics of the system, and able to provide reproducible results that allow comparison with other studies. The level of sampling detail is dictated by the complexity of the questions under consideration. Typical questions include what species are present, where, and in what amount. More complex questions may involve the functioning of aquatic macrophytes in nutrient and heavy metal uptake and turnover, their utilization as indicator organisms, and their effects on ambient water quality conditions.