bluuebunny/crossref_metadata_2025 huggingface dataset:
Time-Resolved Measurements of Spray Drop Size and Velocity
Authors: Bachalo WD , Rudoff RC , Sankar SV
Published: March 2009

The phase Doppler method was applied to the measurement of a swirl-stabilized spray flame. A discussion on the nature of the sampling statistics is provided to assist in the interpretation of the results. Comparisons of the mean drop size obtained in the burning and nonburning spray were made to assess the reliability of the data and to provide information on the drop evaporation rate. At the station considered, the mean sizes were similar at the center indicating a low evaporation rate. The mean drop size increased with radial distance in the burning case due to the loss of the small drops by evaporation. Time of arrival of the drops was measured and revealed pulsations or clustering of the spray. These clusters were most pronounced when injecting into a turbulent flow field with large scale eddies. In the spray flame, the drop clusters appeared to be correlated with the periodic instabilities in the flame. The local drop number density within the clusters was estimated to be an order of magnitude greater than the long time average number density. A fast Fourier transform analysis of the cluster arrival frequency showed that, over short time intervals, there was a periodicity to the cluster formation.
Volatile Agent Monitoring
Authors: Whitcher C
Published: March 2009

A case for routine monitoring of volatile anesthetic agents (halocarbons) is based on presumptions of enhanced patient safety, quality patient care, and economy. The patient under anesthesia stands to benefit when halocarbon concentrations in anesthetic gas mixtures are precisely known. Although dial settings of halocarbon vaporizers may roughly approximate halocarbon concentrations present in anesthetic breathing systems, several factors contribute to discrepancies between dial-set concentrations and directly measured concentrations. These discrepancies are often clinically significant. The variables causing discrepancies are complex, being influenced by multiple factors such as the duration of anesthesia, flow rates of gases employed with halocarbons, and vaporizer accuracy. These variables are often difficult to predict and correct for. Therefore, the continuous monitoring of halocarbon concentrations in anesthetic breathing systems offers the most viable method of assessing the halocarbon concentrations present.

Halometry is likely to prove cost-effective on at least two counts, including facilitation of economical reduced flow-rate anesthetic techniques, which conserve expensive halocarbons, and decreased anesthetic mishaps due to over- and underdosage, which may reduce litigation and insurance rates.

Halometers are readily available for routine use. Clinically useful features include frequency response sufficient for breath-by-breath analysis, as end-tidal concentrations are related to anesthetic depth. Readability to two significant figures is also useful. The capability of specific agent recognition seems important primarily when vaporizers are easily misfilled with wrong agents. The overall complexity of patient monitoring need not be objectionably increased by routine halometry. The time may be appropriate for a halometry standard.
Gy's Particulate Material Sampling Theory
Authors: Bilonick RA
Published: March 2009

An outline of Gy's contributions to particulate material sampling is presented. Gy's theory provides a comprehensive framework that integrates all aspects of sampling particulate materials such as coal, ores, pulps, industrial and municipal effluents, and environmental contaminants. The theory defines and quantifies the two types of heterogeneity (constitution and distribution) and shows how they can be empirically measured using either expensive variographic information or often more readily available size—density information. These results provide principles for constructing sampling devices free from bias and excessive noise. They also provide practical methods for realistically estimating sampling precision for both increment processes (e.g. cross–stream samplers) and splitting processes (e.g. riffle splitters) without requiring significant additional work. The theory also provides practical methods for investigating the potential bias in sampling equipment and methods.
Evaluation of a Field-Portable Supercritical Fluid Extraction Apparatus for Rapid Characterization of Contaminated Soils
Authors: Wright BW , Wright CW , Fruchter JS
Published: March 2009

Rapid, field-portable methods for measuring the concentration of semivolatile organic pollutants are desirable for on-site characterization of contaminated sediments and soils. In addition to providing efficient site assessment capability, rapid characterization methods would also be highly useful at sites undergoing remediation treatments. As an alternative to current methods, supercritical fluid extraction (SFE) has been evaluated for in-the-field coal and petroleum gasification waste site characterization. The gas-like mass transfer properties of supercritical fluids allow more rapid extraction rates and more efficient penetration of the matrix than conventional solvent extractions. The method has proved to be rapid, reproducible, and successful in several field trips.
An Evaluation and Comparison of the Photovac Tip II and HNu PI 101 Total Organic Vapor Analyzers
Authors: Accra LA , Hafferty AJ
Published: March 2009

The HNu PI 101 photoionization detector (PID) based instrument has historically been used for field investigations and site safety determinations at Ecology and Environment, Inc. (E & E). Photovac, Inc. has more recently introduced the TIP II, which operates on the same principles and serves the same purpose as the HNu PI 101. Both instruments can provide nonqualitative, semiquantitative data regarding the presence of ionizable species in ambient air. E & E, under its Zone II Field Investigation Team (FIT) contract with the Environmental Protection Agency (EPA), has completed a comprehensive side-by-side evaluation of the TIP II and PI 101 to determine the utility of the TIP II for the EPA preremedial program. Manufacturer's literature was considered, including instrument descriptions, and design specifications, as well as a comparative evaluation of instrument user manuals. Laboratory test results of instrument operational parameters were evaluated, including battery tests, evaluation of controls, zero stability, flow rates, instrument response time, and response fluctuation. Instrument performance with selected standard gases was compared in a controlled environment. An examination of field instrument performance was conducted. Test results indicate that there are differences in the performance and operation of the PI 101 and TIP II. These differences should be considered by field personnel when the use of an air monitoring instruments are used for field operations.
The Automated Determination of Volatile Organic Contaminants in Ambient Air and/or Soil Gas by Gas Chromatography with Selective Detectors
Authors: Kirshen N , Almasi E
Published: March 2009

Volatile Organic Contaminants (VOCs) are major air pollutants in our environment. Whole air sampling has become the primary method for sampling air with EPA method TO-14. With this technique, an air sample is drawn through a cryogenically cooled trap to freeze out and concentrate VOC contaminants. The trap is then quickly heated and the VOCs are transferred to a cryogenically cooled column. Several variations and improvements have been studied: 1) automation for multiple samples, 2) use of a variable temperature absorption trap to eliminate cryogenics and a water removal device, and 3) elimination of the requirement for a cryogenically cooled oven. Two automated analytical systems are discussed: a fixed and a variable volume system. Precision, method detection limits, system linearity, and carryover are reported. Finally, ambient, dry-cleaner, and indoor air samples are analyzed using the techniques described.
An Advanced Autosampling System for Gas Chromatography-Mass Spectrometry
Authors: DeWald JT , Koch CA
Published: March 2009

The authors have developed a software enhancement for the Hewlett-Packard RTE gas chromatograph/mass spectrometer (GC/MS) data system that allows for feedback from quality control (QC) samples to control the autosampler sequencing. In addition, the system automatically produces numerous QC data summary reports for analyst evaluation. The enhancements were developed in an Environmental Protection Agency (EPA) contract laboratory where strict tuning and calibration criteria must be met before any samples can be run and where significant review of the data by the analysts is required. One of the advantages of such a system is the ability to produce successful multiple shift runs. This ability allows for 24-hour and weekend operation of GC/MS systems with limited analyst intervention, thus increasing the utilization of limited resources. A second advantage of the system is its ability to automatically produce summary reports. These aid the analyst in evaluating data quality for such parameters as surrogate recovery and target analyte identifications. In addition, the production of these reports in a format to aid quick review of data quality allows the analysts to perform more complete reviews in much less time. This paper discusses the design of this software (referred to as SMART), its application to realworld laboratory situations, and suggestions for future improvements.
Determination of OCDD and OCDF in Soils and Biological Samples by GC/ECD
Authors: Draper WM , Park H , Stephens RD
Published: March 2009

This paper describes advancements in the gas chromatography-electron capture detector (GC/ECD) determination of octachlorodibenzodioxin (OCDD) and octachlorodibenzofuran (OCDF). OCDD and OCDF (OCDD/F) serve as markers or surrogates for the more toxic polychlorinated dibenzodioxins and dibenzofurans (PCDD/Fs). The current procedure allows baseline separation of OCDD/F on DB-17 capillary narrow-bore or megabore columns. OCDD/F are relatively involatile, but can be successfully injected using capillary on-column or packed column inlets (for megabore columns), and the latter can be automated. Soil method detection limits (MDL) have been reduced by a factor of ten to 0.4 to 0.8 ng/g for OCDD and OCDF, respectively, sensitivity comparable to GC/MS procedures. An optional Florisil® cartridge cleanup isolates OCDD/F from chlorinated pesticides, polychlorinated biphenyls and other coextracted environmental chemicals. Instrument detection limits for OCDD and OCDF in eggs are in the 0.5 – 1.0 ng/g lipid range after defatting samples by gel permeation chromatography (GPC).
Headspace Screening/Capillary Column GC/MS Analysis for Volatile Organics: Validation Studies and Applications
Authors: Flynn LR , Bass SW , Meierer RE
Published: March 2009

The use of a headspace sampling device coupled with a gas chromatograph/mass spectrometer (GC/MS) equiped with a very large bore capillary column allows the rapid characterization of sample constituents. The MS detector operated in the full scan mode provides adequate sensitivity as well as excellent specificity. Most of the compounds on the volatile target compound list are amenable to analysis using the headspace technique and information on sample constituents not in the analytical standard is available through library searches. The use of the MS as a detector reduces the requirement for chromatographic separation.
Analysis for N-Methylcarbamate Pesticides by High Performance Liquid Chromatography in Environmental Samples
Authors: Okamoto HS , Wijekoon D , Esperanza CE , Cheng JC , Park SL , Garcha JS , Gill SS , Perera KS
Published: March 2009

This method was developed for the routine analysis of ten N-methylcarbamate pesticides in environmental aqueous and soil samples. Aqueous samples are extracted with dichloromethane, while soils are extracted with acetonitrile. The extracts are solvent exchanged to methanol prior to analysis. Analysis entails a high pressure liquid chromatographic separation on a C18 reverse phase column, post column derivatization and monitoring the resulting fluorophore by fluorescence detection. The standard derivatization procedure is based on alkaline hydrolysis of the N-methylcarbamate to yield methylamine, which in turn is reacted with o-phthalaldehyde (OPA) and 2-mercaptoethanol to form 1-(2-hydroxyethylthio)-2-N-methylisoindole. For routine quantitation the product is excited at 340 nm and the fluorescence emission detected through a 418 nm cut-off filter. Initial laboratory data indicate that method detection limits, precision and accuracy should be reasonable for routine environmental samples. The detection limits for clean water samples are estimated to be in the 1 to 10 ug/L range, while soil samples are estimated to be in the 10 to 50 ug/Kg range.
Evaluation of Sample Extract Cleanup Using Solid-Phase Extraction Cartridges
Authors: Lopez-Avila V , Yeager S , Beckert WF
Published: March 2009

Fractionation or cleanup of samples extracts prior to instrumental analysis is used to remove coextracted materials that often interfere with the determination of target analytes. Such fractionations and cleanups are usually accomplished by column chromatography, gel permeation chromatography, or acid-base partitioning. This paper describes the application of solid-phase extraction cartridges containing silica gel, Florisil, or alumina to the fractionation and cleanup of sample extracts containing organochlorine pesticides, polychlorinated biphenyls, and phthalate esters. Several solvents were evaluated for cartridge elution to establish a procedure that will allow separation of polychlorinated biphenyls and phthalate esters from organochlorine pesticides. Furthermore, cartridge loading and the effects of matrix interferents such as those present in corn oil and diesel hydrocarbons were investigated.
Supercritical Fluid Extraction and its Application to Environmental Analysis
Authors: Lopez-Avila V , Beckert WF , Billets S
Published: March 2009

Sand samples spiked with Aroclor 1232/1260, 17 organochlorine pesticides, 25 organophosphorus pesticides, 43 neutral/acidic compounds, and 16 PAHs were extracted with supercritical carbon dioxide at various pressures and temperatures to establish whether or not such type of compounds can be recovered from solid matrices by supercritical fluid extraction. A few Standard Reference Materials from NIST, spiked only with PAHs, were also evaluated.
The Application of Supercritical Fluid Capillary Chromatography to the Analysis of Appendix-VIII and IX Compounds
Authors: Pospisil PA , Marcus MF , Kobus MA
Published: March 2009

Supercritical fluid chromatographic technology was used to successfully chromatograph over 270 Appendix VIII and IX compounds on a single column, within one hour. Retention times, response factors and chromatographic conditions for the analysis of a very broad range of compound classes are presented.

The Appendix VIII and IX lists define the compounds of major regulatory importance in a broad range of solid wastes and groundwater. They include upwards of several hundred organic substances, covering a broad compositional, polarity, volatility, thermal and hydrolytic stability ranges. Some of the entries are mixtures such as coal tar, creosote, cresols, PCB'S, aflatoxins, and dioxins, which may contain hundreds of individual components. Significant numbers of these compounds can be difficult to determine by existing analytical techniques because of their lack of volatility and low thermal stability. The application of this technology will cost reduce and streamline existing practices and open new avenues of analytical research in the areas of improved calibration and confirmatory analysis.
Volatile Organic Sample Preservation for a Soil, Sediment or Waste
Authors: Urban MJ , Smith JS , Schultz EK , Dickinson RK
Published: March 2009

Volatile organic compounds (VOCs) are rapidly volatilized from moist soil and sediment. Losses in VOC concentrations can amount to as much as three orders of magnitude during the sampling, transportation, storage, and analytical processes. These losses usually occur during various sample handling procedures. Use of a narrow-mouth sample container such as a 40 mL volatile organic analysis (VOA) vial necessitates breaking up the soil sample, thus increasing surface area and VOC losses.

Laboratory sample preparation procedures also lead to VOC losses.There is headspace loss when the sample jar is opened. Stirring the sample promotes VOC losses, and the weighing process can lose major amounts of VOCs because of the small sample sizes recommended for purge and trap VOC analysis.

In this study to minimize the losses of VOCs due to sample handling, the soil VOCs were preserved with methanol in the field. The U.S. EPA Contract Laboratory Program (CLP) medium level VOC analytical methodology with minor changes was then followed for quantitative measurement.

In a site investigation where seven chlorinated chemicals were present, samples were taken from a split spoon using both the 40 mL VOA vial soil sampling and the methanol field preserved sampling methods. The analyses of these samples indicated a difference of approximately two orders of magnitude between the two methodologies. The methanol method gives results that are more accurate and representative of the environmental field conditions. However, the detection limit is about 250 μg/Kg. The theoretical detection limit for low level VOC analysis using CLP methodology is 5 μg/Kg, however, given the documented VOC losses of approximately two orders of magnitude this low level detection limit specification is misleading. After accounting for potential VOC losses due to sample handling the methanol preparation methodology appears to be more applicable to measurement of low levels of VOCs in soil than existing procedures.
Holding Times of Volatile Organics in Water
Authors: Bottrell DW , Fisk JF , Robertson GL , Petty JD , Dempsey CH , Bartling ML
Published: March 2009

“Holding Time” can be defined as the maximum period between sampling and analysis before the occurrence of significant sample degradation. They are stipulated because of the recognition that chemical and physical characteristics may change during this period. However, sampling method, sample container, storage (conditions and preservative, as well as time), shipping conditions, etc, contribute to a collective effect on sample stability. This paper discusses the significance of holding time as a variable relative to method performance and suggests alternative preservation techniques.
A Comparison of the Performance Characteristics of Sorbent Column Packing Materials Used for Purgeable Organics Analysis
Authors: Weston CA , Speis D , Albert RP
Published: March 2009

The use of silica gel as a component of the sorbent column trap for the determination of volatile organics by GC/MS (SW-846 Method 8240) has been found to lead to water vapor buildup in the instrument vacuum system which results in loss of sensitivity, inaccuracies in the data and in some cases automatic shutdown of the MS due to excess pressure in the ion source.

Several alternative sorbent trap packings have been investigated as a means of alleviating the detrimental effects resulting from the retention of excess water vapor in the GC/MS system. The most successful combinations have excluded silica gel as a sorbent column component.

Instrument response data were generated for the volatile organic target compounds listed on the USEPA Contract Laboratory Program (CLP) and several gaseous Freons using sorbent traps with and without silica gel. Method detection limits were experimentally determined on each trapping system and evaluated for statistically significant differences. Statistical comparisons of trapping efficiency were also performed for the two systems. The method calibration requirements (SPCC and CCC) were evaluated against the method criteria for the silica gelfree sorbent column.

Statistically significant deviations in silica gel-free trap performance were minor and did not adversely affect the achievement of the method performance criteria for SW-846 Method 8240.
Validation of a Microwave Digestion Method for Solid Wastes
Authors: Binstock DA , Grohse PM , Gaskill A , Sellers C
Published: March 2009

The techniques that are typically used to prepare RCRA wastes for analysis for metals and other elements are generally relatively time consuming, requiring several hours to several days to complete. They also often involve the use of acid digestions and thermal decomposition steps which may result in analyte losses, incomplete recoveries, or sample contamination. These limitations are well known to the analytical community and to the end users of these data in the U.S. EPA, States, and industry. The resulting inefficiency of these techniques reduces laboratory sample throughput, drives up the cost of analytical testing and impedes decisionmaking. Given these concerns, the OSW Methods Section is interested in developing cost-effective sample preparation techniques for metals and other elements in environmental and process waste samples. Once developed, these techniques can then be written as methods for inclusion in the U.S. EPA “Test Methods for Evaluation of Solid Waste” (SW-846) [1] and made available to the user community.

A microwave-assisted sample preparation method for determining elements in solid waste has been developed (Method 3051). This paper reports on the validation of this method by a collaborative study to determine its precision and accuracy. Both qualitative and quantitative aspects of the method were assessed. Qualitative factors evaluated were ease of use and time requirements. Quantitative factors evaluated were the bias and the precision (single laboratory and total). The method was compared with U.S. EPA Method 3050, an open-vessel, hot plate digestion method.
Leachability of Chemicals from Hazardous Waste Land Treatment Sites
Authors: Erickson DC , Rogers LA , Loehr RC
Published: March 2009

Chemicals in soil are subjected to environmental factors which may influence their mobility. Climatic stress can alter soil structure and chemical retaining properties and low pH can influence chemical mobility. The Toxicity Characteristic Leaching Procedure (TCLP) is being used to assess chemical mobility. The objectives of this research were to: (a) determine the leachability of specific metals and organics from soils at hazardous waste land treatment sites using the TCLP, (b) evaluate the mobility of hazardous constituents as a function of soil depth for these sites, and (c) determine the effects of weathering cycles on the leachability of these constituents.

Soils from several hazardous waste land treatment sites initially were characterized for selected metals and organics and their mobility determined using the TCLP. The soils then were subjected to repetitive freeze/thaw and wet/dry cycles, and retested using the TCLP to determine whether significant changes in chemical mobility were caused by the weathering action. Metals analyses for both the weathered and non-weathered samples indicated that, of the six metals tested, only zinc exceeded background levels consistently. No clear differences were detected when metal concentrations in TCLP extracts from weathered and nonweathered samples were compared. Organic compounds were not detected in either sets of extracts.
Residual Fuel Oil as Potential Source of Groundwater Contamination
Authors: Davani B , Sanders B , Jungclaus GA
Published: March 2009

As part of the Environmental Protection Agency's (EPA's) continuing effort to develop the basis for listing certain refinery wastes as hazardous, fuel oil tank bottoms were characterized for semivolatile organic compounds including selected polycyclic aromatic hydrocarbons (PAHs).

No. 6 fuel oil samples were collected from four areas, one in Kansas City and three in Northern California. Soxhlet extraction with methylene chloride, followed by fractionation on alumina, were used to isolate the PAHs in fuel oil samples. The sample extracts were analyzed by high resolution gas chromatography and gas chromatography/mass spectrometry. Total selected PAH concentrations in the fuel oil samples ranged from 71 to 6,560 ug/g. Higher concentrations of other aromatic compounds including alkylated PAHs and sulfur-containing aromatic hydrocarbons were also detected in the samples.

Additionally, laboratory-scale soils columns (2 cm ID and approximately 10 cm long) were used to model the transport of oily waste in the subsurface and potential migration into the groundwater. In one set of the experiments, the oil was introduced on the top of the soil using a disposable minipipet and was then allowed to migrate freely. In the second set of experiments, the soil columns were subjected to a small pressure using pure nitrogen gas. All the studies were conducted at room temperature and the soil columns were saturated with water prior to the addition of the fuel oil.

Several oil mobility studies were performed with fine and coarse soil. The fine soils initially showed no visible mobility for the fuel oil sample during the 17-day experimental period. However, additional experiments using oil/soil ratios of 1:1 and 1:2 (30 g of soil) showed movement of the fuel oil through the entire length of the fine soil column (10 cm). The oil moved through the coarse sandy soil column and also eluted from the coarse column when the same oil/soil ratios as above were used. The fuel oil passed through the columns with little absorption (in a matter of minutes or hours) when the columns were pressurized at approximately 20 psi with nitrogen gas.

In a related study, several Toxicity Characteristic Leaching Procedure, “TCLP” experiments[1] were conducted to assess the feasibility of using TCLP for this type of oily waste and to compare the TCLP results with the corresponding soil column studies. In light of the results obtained in this set of experiments, the applicability of TCLP to this type of oily waste must be cautioned. Furthermore, due to dissimilar processes and experimental conditions involved in the TCLP and column studies, it was concluded that comparison of the two procedures may not be appropriate.
The Definition and Classification of Hazardous Waste Matrices
Authors: Pospisil PA , Marcus MF
Published: March 2009

Analytical chemistry plays a major role in the hazardous waste field, but the hazardous waste analyte/matrix relation generates an additional dimension of sample complexity not encountered in other disciplines. Hazardous waste analytes are clearly defined by regulations; however, no classification systems exist for hazardous waste matrices. This presents a problem when applying regulatory methodology to waste streams, as no information is included as to the methods applicability or suitability.

Twenty four basic hazardous waste classes have been defined based on materials most frequently occurring in waste management operations. The definitions are based on the physico-chemical composition of about 1000 samples received at the CWMI Technical Center. The system can classify 90 to 95 per cent of the samples received within CWMI. Multiphase mixtures can easily fit into the system by considering each phase as a unique matrix. All of the hazardous wastes having waste classification codes can be fit into this system. The development of a uniform, systematic waste classification system provides a viable solution as to which analytical methods are applied to the diverse types of hazardous wastes. This work parallels and facilitates advances in the areas of hazardous materials disposal research, analytical methods development, and QA/QC programs, by providing uniform and realistic reference material classifications.
Quality Assurance as Viewed by a Data User
Authors: Brown RD , Marinenko G , Egan DE
Published: March 2009

Although considerable attention is given to the concept of quality assurance during the sample collection, laboratory analysis, and data confirmation stages associated with the production of environmental data, few quality assurance concepts have been incorporated into the use of such data in decision-making. This paper presents information feedback from individuals involved in using environmental data for the purpose of evaluating uncontrolled hazardous waste sites. The paper discusses the principles of quality assurance when using data for pre-remedial site screening purposes. The few data left for decision-making after data winnowing, possible use of qualified data, the need for awareness of background variability, and the dependence on thorough documentation are discussed. A case example is provided.
Deformability of Zirconium-Lined Cladding Tube in Cold Pilgering
Authors: Abe H , Tarui H , Kobayashi T , Honji M , Konishi T
Published: March 2009

The effect of fabrication parameters on the inner microfissure in the Zr-lined cladding tube has been investigated. The results were as follows: 1. The Q-value during cold pilgering is an important factor for inner fissures. When the Qvalue is larger than 1.5, the tube is subject to the favorable effect on the fissure. 2. The inner fissures are dependent on grain size of the Zr liner. The smaller grain of the mother tube before cold pilgering has a good effect on the inner fissure of the tube after cold pilgering. 3. Pickling before cold pilgering has proven to be important for decreasing defects in the bore of the Zr-lined tube.

These results are very useful for improving and assuring the quality of the Zr-lined cladding tube.
Processing Map and Hot Working Characteristics of Zircaloy-2
Authors: Chakravartty JK , Prasad YVRK , Asundi MK
Published: March 2009

The constitutive flow behavior of Zircaloy-2 in the temperature range of 650 to 850°C and strain rate range of 0.001 to 100 s-1 has been studied using constant true strain rate hot compression tests. On the basis of these data, a processing map has been generated using the concepts of a Dynamic Material Model. The processing map has revealed a domain of dynamic recrystallization at an optimum condition of 800°C and 0.1 s-1. The material undergoes microstructural instabilities at strain rates higher than 1 s-1 and temperatures lower than 700°C. The observed constitutive flow characteristics have been validated with the help of large scale extrusion experiments conducted at two different temperatures and various extrusion ratios using a conical die semi-angle of 45°. The microstructures observed in the extruded material confirmed the predictions of the processing map. The optimum processing parameters for hot extrusion are found to be 800°C and a mean strain rate of 0.1 to 1 s-1.
Establishing Statistical Models of Manufacturing Parameters: Zircaloy-4 Cladding Tube Properties
Authors: Senevat J , Pape JL , Deshayes J-F
Published: March 2009

The effect of pilgering and cold-work parameters on contractile strain ratio and mechanical properties was investigated using a large population of Zircaloy tubes. Statistical models were established between: (1) contractile strain ratio and tooling parameters. (2) mechanical properties (tensile test, creep test) and cold-work parameters, and (3) mechanical properties and stress-relieving temperature.
Texture Control in Zircaloy Tubing Through Processing
Authors: Cook CS , Sabol GP , Sekera KR , Randall SN
Published: March 2009

Processing parameters have been examined in an effort to identify methods for meaningful control and enhancement of texture in Zircaloy tubing. The parameters found to have significant influence on texture are those that describe the distribution of plastic deformation (Q ratio) between the radial and circumferential directions due to wall and diameter reduction during processing by the cold pilger mill. Included in this work was the development of a new method of texture enhancement using an increment of positive circumferential deformation by hydraulic expansion. While the effect of deformation history on texture in zirconium alloy tubes has been reported extensively, the results of this effort reveal that significant control of texture is available through the control of texture of the material at intermediate stages of processing. The results of this work also revealed that the relationship between the two primary methods of texture characterization in Zircaloy tubes (i.e., radial texture parameter and contractile strain ratio) is dependent on the metallurgical condition of the material.
Microstructure of Zr-2.5Nb Alloy Pressure Tubing
Authors: Northwood DO , Meng-Burany X , Warr BD
Published: March 2009

The microstructure of Zr-2.5Nb nuclear reactor pressure tube material has been studied using electron microscopy. X-ray diffraction, and energy dispersive X-ray spectroscopy techniques. The materials studied contained a range of impurity contents with iron ranging from 300 to 1500 ppm in both the cold-worked and cold-worked + annealed (24 h/560°C) conditions. Cold-worked tubes consisted of deformed α-Zr grains with a network of β-Zr (∼20wt%Nb) surrounding the α-Zr grains. Annealing produced a decomposition of the β-Zr phase into α-Zr and β-Nb (∼83 wt% Nb). Cold-worked tubing with Fe contents ⩾500 ppm also contained a very small volume fraction of Zr2Fe precipitates having a tetragonal structure, β-quenching during fabrication of the tubing appeared to suppress the precipitation of Zi2Fe. On annealing, both Zr(FeCr)2 and Zr2Fe precipitates were formed. The Zr(FeCr)2 precipitates had either the C-15 cubic or C-14 hexagonal Laves phase structure. It is proposed that on annealing at 560°C the β-Zr phase (containing Fe and Cr in solution) transforms to α-Zr + β-Nb + Zr(FeCr)2 phases.
Fracture Toughness of Irradiated Zr-2.5Nb Pressure Tubes from CANDU Reactors
Authors: Chow CK , Coleman CE , Hosbons RR , Davies PH , Griffiths M , Choubey R
Published: March 2009

About 400 pressure-tubes made of cold-worked Zr-2.5Nb are used in a CANDU power reactor to contain the nuclear fuel and the heat transport fluid, heavy water, at between 250 to 310°C at a pressure of about 10 MPa. The fracture toughness of these tubes is needed to determine if they are fit for service. We have measured the fracture toughness by bursting 450 mm long tube sections and using 17 mm curved compact toughness (C(T)) specimens, employing the J-integral resistance curve method in both cases. The burst test is expensive but it simulates the stress state under which the pressure tubes operate, while the small specimen method is more economical although the interpretation of data is more difficult.

The results indicate that the fracture toughness decreases rapidly during the first few years of operation, but when the fluence reaches about 3 × 1025 n/m2 (E > 1 MeV) the decrease in toughness slows down. The post-irradiation toughness is not affected by either the initial mechanical properties or the difference in irradiation temperatures at the inlet and outlet of the fuel channel.

Although the results from small specimens and the burst tests show the same trend for the decrease of toughness with fluence, the JR curves obtained from the C(T) specimens are more conservative. Reasons for the differences are discussed. The evolution of microstructure during irradiation was also studied in an attempt to correlate the change to fracture toughness.
Investigation of Nodular Corrosion Mechanism for Zircaloy Products
Authors: Wang CT , Eucken CM , Graham RA
Published: March 2009

Flat mill products of Zircaloy-4 and controlled-chemistry Zircaloy-2 were processed using different rolling schedules in order to generate different textures and other metallurgical conditions. Tubular products of three heats of controlled-chemistry Zircaloy-2 were also processed using various thermo-mechanical parameters and different tube reduction schedules. Samples were taken for 500 and 520°C steam autoclave tests and texture and microstructure examination. Intermetallic precipitates were analyzed for mean diameters and particle size distributions using optical high magnification photographs. Matrix concentrations of Fe, Cr, and Ni were analyzed by electron microprobe with automated stage control.

Results showed that the nodular corrosion resistance for controlled-chemistry Zircaloy-2 was excellent, while that for Zircaloy-4 was rather poor. The Zircaloy-2 tubeshell may be annealed up to 663°C/2h without detriment to the nodular corrosion resistance of the final size tubing if other fabrication variables are properly controlled. The optimum process for tube reducing is a high Q ratio and high percent of reduction in area. Neither β quench nor α + β treatment after tube extrusion is required to produce cladding tube that is free of nodules in 500 or 520°C autoclave tests. Low basal pole densities are generally related to high corrosion weight gains. The accumulated annealing parameter, ΣA, can generally predict the nodular corrosion behavior of the material, but it cannot account for the higher corrosion weight gain at an intermediate stage and lower weight gain at the final size.

The most significant correlation is established between variation in concentrations of iron, chrome, and nickel in Zircaloy-2 and nodular corrosion behavior of the material. A depletion of these elements in the matrix or a large spacing between intermetallic precipitates causes poor nodular corrosion resistance. The positive effect of cold work on the nodular corrosion resistance is attributed to increasing the yield strength of the substrate.
Development of Highly Corrosion Resistant Zirconium-Base Alloys
Authors: Isobe T , Matsuo Y
Published: March 2009

Static autoclave tests in steam at 673 K and tensile tests at room temperature were conducted to investigate the effects of alloying elements, such as tin (0.2 to 1.5 wt%), niobium (0.05 to 1.0), iron (0.2 to 0.6), chromium (0.1 to 0.4), molybdenum (0.05 to 0.5), and vanadium (0.1 to 0.5), and heat treatments on the corrosion resistance and mechanical properties of niobium-containing zirconium-base alloys, Moreover, the characterization of second-phase particles was carried out by scanning transmission electron microscopy (STEM).

The corrosion resistance of zirconium-base alloys compared with that of Zircaloy-4 (nominal composition: Zr-1.5Sn-0.2Fe-0.1Cr) was significantly improved by the reduction of the Sn content by 0.5 wt% and by a small addition of Nb (about 0.05 to 0.2 wt%). However, the decrease in solute Sn atoms degraded mechanical properties such as ultimate tensile strength and 0.2% yield strength.

The increase of the total content of Fe and Cr from 0.3 to 0.7 wt% improved the mechanical properties without affecting the corrosion resistance. Small additions of Mo and/or V resulted in a further improvement of mechanical properties. Thus it is possible to design alloys with equivalent mechanical properties and superior corrosion resistance to Zircaloy-4.

The corrosion resistance increased and the average size of precipitates decreased from 0.1 to 0.05 μm with the decrease of the Fe/Cr ratio from 6.0 to 0.5 in the niobium-containing zirconium-base alloys.

Detailed investigations on the effects of annealing temperatures on the corrosion behavior of the zirconium-base alloys were also performed. Results showed that increasing the Nb content of the alloys lowered the most suitable annealing temperature for corrosion resistance. These experiments led to the development of niobium-containing zirconium-base alloys with high corrosion resistance.
Effect of Alloying Elements on Uniform Corrosion Resistance of Zirconium-based Alloys in 360°C Water and 400°C Steam
Authors: Harada M , Kimpara M , Abe K
Published: March 2009

The effects of alloying and impurity elements on the uniform corrosion properties of zirconium-based alloys were studied, Tin, iron, chromium, nickel, vanadium, niobium, and tantalum (as alloying elements), and oxygen, carbon, nitrogen, silicon, aluminum, and phosphorus (as impurities), were selected. These alloys consisted of two groups: Zircaloy-type alloys and zirconium-based alloys. Corrosion tests were performed in 633 K water and 673 K steam for a total of 7200 h. The effect on hydrogen pick-up was also studied.

Zircaloy-type alloys showed typical corrosion behavior with a rate transition. In the pretransition region almost all alloys showed the same behavior, but the post-transition corrosion rate increased with tin content. Iron increased the post-transition corrosion rate in 673 K steam; the effect of chromium was negligible. A small addition of nickel was effective in reducing post-transition corrosion rate, but larger amounts did not markedly improve the resistance. The effect of impurities was also negligibly small within the variation of the contents in this study. The effects of alloying elements in the binary alloys were basically the same as that in Zircaloys, but niobium and tantalum had a remarkable effect in improving the corrosion resistance. The effects of tin, iron, and chromium on hydrogen pick-up fraction were small; nickel, however, had a significant effect. The composition of second-phase particles in Zircaloys varied with the contents of alloying elements, but seemed to have no relation to the uniform corrosion behavior of Zircaloys.

The rate transition in corrosion behavior was assumed to be related to the relief of compressive stress in the growing oxide by the transformation from a monoclinic to a tetragonal or cubic structure. Furthermore, tin might have the effect of stabilizing monoclinic zirconium oxide. Second-phase particles, Zr(Cr.Fe)2, were oxidized to orthorhombic structure from hcp structure and seemed to have little effect on the morphology of oxide around them and consequently on corrosion behavior.
Microanalysis of the Matrix and the Oxide-Metal Interface of Uniformly Corroded Zircaloy
Authors: Wadman B , Andrén H-O
Published: March 2009

The matrix composition in one Zircaloy-2 (Zry-2) and four Zircaloy-4 (Zry-4) materials has been measured with the atom probe technique. It was found that only about 10% of the alloying elements Fe, Cr, and Ni added to the alloy remain in solid solution in the matrix of nuclear fuel claddings. No significant difference in matrix concentration of Fe and Cr could be detected in Zry-4 materials with different heat treatment and different corrosion resistance. Even a Zry-4 material analyzed directly after a β-quench operation had a matrix concentration of only 0.02 wt% Fe and 0.03 wt% Cr.

Atom probe analysis was also used to study the oxide-metal interface in oxide layers formed in dry air and water on needle shaped Zry-4 specimens. Transmission electron microscopy of the oxide layers showed that these were approximately 10 nm thick and contained 5 nm sized oxide crystallites in an amorphous layer. According to atom probe analysis, the thin oxide layers had a low oxygen content, less than 50 atomic percent.
Comparison of Zircaloy Corrosion Models from the Evaluation of In-Reactor and Out-of-Pile Loop Performance
Authors: Billot Ph , Giordano A
Published: March 2009

Corrosion models are generally able to provide satisfactory predictions of inreactor performance. Nevertheless, in order to emphasize the theoretical or empirical aspects of the corrosion process and to improve the accuracy of models, the major objectives of the present study are: • To provide a comparison of the published corrosion models (CEA, EPRI, etc.). • To discuss the main assumptions described in the proposed models.

Consequently, a methodology was conducted with the objective of providing the following information: • The main assumptions used to describe the thermal/hydraulic corrosion process in the overall models are presented and modelled in a computer program. • Experimental corrosion data are collected from a great number of rods taken from seven different power reactors, from the CIRENE out-of-pile loop, and from autoclave tests.

Metallographic examinations of SRA Zircaloy-4 tubings constitute the experimental data required for the determination of the accuracy of the corrosion models. Measurements give an idea of the waterside corrosion behavior of Zircaloy-4 for the following encountered operating conditions in French or foreign reactors: • One to four cycles of irradiation in 900 MWe PWRs. • Three cycles of irradiation in a four-loop PWRs characterized by a severe thermal/hydraulic environment. • Four to five cycles of irradiation cycles of 4.5% 235U or 3.1% 235U enriched fuel rods leading to average rod burnups in the range of 48 000 to 55 000 MWd/tU. • 365 effective full power days in the CIRENE out-of-pile loop. • Autoclave tests.

The power history of the analyzed rods and the thermohydraulic design of reactors are used for effective data reduction. The operating parameters as a function of time constitute the unique data base required for the prediction of Zircaloy-4 performance by all the corrosion models to be tested.

The comparison of measured and calculated corrosion data from the in-pile and out-of-pile tests is performed and described.

The differences between corrosion models allow for the assessment of the influence of varied parameters on the corrosion rates of the Zircaloy-4 cladding tubes.

In particular, the assumptions concerning the effect of thermal conditions (heat flux, wall temperature), the irradiation environments, and the chemistry data (lithium content in the coolant) are discussed through the different models.
Corrosion of Zircaloy-4 Pwr Fuel Cladding in Lithiated and Borated Water Environments
Authors: Bramwell IL , Parsons PD , Tice DR
Published: March 2009

A series of isothermal investigations have been performed in static autoclaves at 623 K in both standard start of cycle coolant and a series of more concentrated lithium and lithium-boron solutions to simulate the environment which might result within a porous oxide due to hideout. In solutions containing 220 ppm of lithium, the presence of as little as 50 ppm of boron had a marked ameliorating effect on the corrosion rates of Zircaloy-4. The quantity of lithium which became incorporated in the scale was less in the presence of boron and, in general, decreased as the boron concentration in the bulk solution increased. Preliminary results under heat flux in similarly concentrated environments have suggested that the results are also applicable to the real situation in a reactor, since the volatilization of boric acid under boiling was not so great that boron was prevented from reducing the corrosion rate. In contrast, experiments with the same lithium concentration but just 10 ppm of boron resulted in consistently higher weight gains than in the lithium-only test, suggesting that the concentration of boron must exceed a certain critical value before corrosion can be inhibited, and that concentrations below this threshold increase corrosion rates.
Investigation of Variables That Influence Corrosion of Zirconium Alloys during Irradiation
Authors: Urbanic VF , Choubey R , Chow CK
Published: March 2009

The in-reactor corrosion of Zircaloy-2 and Zr-2.5Nb pressure tube materials is being studied by exposing small specimens in water-cooled loops in the NRU research reactor. Experiments are designed to investigate the effects of fast-neutron irradiation, water chemistry, temperature, and pre-oxidation on the corrosion behaviour. Preliminary results show that inreactor corrosion rates of both alloys increase with increasing concentrations of dissolved oxygen in the water. In the absence of irradiation, only Zr-2.5Nb is sensitive to its presence. Excursions to oxidizing (⟩300 (μg/kg oxygen) water chemistry in nominally low oxygen tests are seen to induce high oxidation rates for both Zircaloy-2 and Zr-2.5Nb during irradiation. The consequences of oxygen excursions are less pronounced on material prefilmed in 673 K steam. The oxides formed in different chemistry regimes are characterized using scanning electron microscopy and capacitance techniques.

Over the temperature range 528 to 568 K, the temperature dependence for corrosion of pickled specimens during irradiation is low with activation energies being marginally higher for Zr-2.5Nb than for Zircaloy-2. In these tests it is seen that fast-neutron irradiation increases corrosion of Zircaloy-2, whereas for Zr-2.5Nb a decrease in corrosion is frequently observed during irradiation.