bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Review and Assessment of the Stress-Intensity Factors for Surface Cracks
Authors: Newman JC 
Published: March 2009

The stress-intensity factor solutions proposed for a surface crack in a finite plate subjected to uniform tension are reviewed. Fourteen different solutions for the stress-intensity factors are compared. These solutions have been obtained over the past 16 years using approximate analytical methods, experimental methods, and engineering estimates.
The present paper assesses the accuracy of the various solutions by correlating fracture data on surface-cracked tension specimens made of a brittle epoxy material. Fracture of the epoxy material was characterized by a constant value of stress-intensity factor at failure. Thus, the correctness of the various solutions are judged by the variations in the stress-intensity factors at failure. The solutions were ranked in order of minimum standard deviation. The highest ranking solutions correlated 95 percent of data analyzed within ±10 percent, whereas, the lowest ranking solutions correlated 95 percent of data analyzed within ±20 percent. However, some solutions could be applied to all data considered, whereas, others were limited with respect to crack shapes and crack sizes that could be analyzed.
Acoustic Emission Surveillance of Boiling Water Reactor Piping Nozzles and Valves
Authors: Hartman WF , McElroy JW 
Published: March 2009

Traditional inservice inspection (ISI) techniques for nuclear power plants are hampered by personnel radiation exposure. There is a genuine need for on-line surveillance methods which can identify areas of possible structural degradation, thereby resulting in reduced inspection time because of concentrated inspection activity. One potential method, acoustic emission (AE) monitoring, is being investigated as a surveillance technique at Philadelphia Electric Company's Peach Bottom Atomic Power Station, Unit 3. The data produced by the AE surveillance are being compared with the ISI results.
Acoustic emission sensors are mounted on two feedwater nozzles, two core spray lines, and one recirculation by-pass line. Also, eleven mainstream safety/relief valves are being acoustically monitored for the detection and measurements of leaks. This paper describes the correspondence of the AE results with the inservice inspection data obtained during two refueling outages. The feasibility of general implementation of AE surveillance is discussed.
Evaluation of Methodology for Quantifying Radiopharmaceuticals in Tertiary-Treated Sewage
Authors: Krieger H , Frishkorn G , Martin E , Jacobs B 
Published: March 2009

The production and utilization of radioactive pharmaceuticals and radionuclides for medical diagnosis and therapy warrant consideration of their fate and their radiation hazard to the population after discharge. Some of these nuclides—198Au, 133Xe, 131I, 99mTc, 85Sr, 75Se, 57Co, and 51Cr—represent curies of activity from a single facility that are being released to the sewers over a year's time. Although their relatively short half-life (6 h to 270 days) and the large sewer dilution may reduce the activity in the waste by several orders of magnitude at the point of treatment, the unpredictable range of decontamination (0 to 90 percent) by normal sewage treatment practices means that some will remain in the final effluent.
Even after tertiary treatment operations, many of these radionuclides will still be present. This tertiary treatment is necessary when sewage effluents are to be used as coolants for nuclear reactors, and the confirmation of these nuclides in these effluents becomes of major concern as possible radiation hazards.
Methodology to identify and measure the activity of five radionuclides—131I, 85Sr, 57Co, 51Cr, and 75Se—has been developed and tested. The validity of the developed procedures has been checked with standardized traces solutions added to different sewage effluents and dried lime-treated sludges. Chemical yields agreed with radiochemical yields, and with 15 litres of sewage, or 10-g sludge, the chemical yields were atleast 70 percent.
Since the normal activity levels of each of these nuclides will be low, nondestructive quantification becomes questionable. The required precision and accuracy can best be satisfied by collecting intermittent samples and by radiochemical analysis of large volumes. Analyses on the influents, sludges, and treated effluents will indicate the overall efficiency of the entire sewage treatment process, provide evidence of the fate of each nuclide discharged into the sewage stream, and indicate whether a potential radiation hazard exists.
Analysis of Environmental Samples—Tennessee Valley Authority's Radiological Environmental Monitoring Program
Authors: Hobbs BB , Clayton WR , Frederick CE 
Published: March 2009

The Tennessee Valley Authority (TVA) has 17 nuclear reactors in seven separate nuclear sites that are either operating, under construction, or in various stages of licensing. As a result, TVA has developed an extensive radiological environmental monitoring program.
TVA's environmental monitoring program began in 1968 as a preoperational program around Browns Ferry Nuclear Plant to determine the levels of natural and man-made radiation present before plant operation. From a relatively modest number of 2000 samples and 8800 analyses in 1968, the number of samples has grown to 10 000 per year and the number of analyses has grown to over 42 000 per year. We expect a threefold increase over the next five years as new areas are added to the monitoring program.
Recognition of the large number of samples requiring analyses, and the desire to identify and analyze for specific isotopic content, led us to conclude early in our program that we would have to perform most analyses by gamma spectrometry. Considering costs and the instrumentation then available to us, we decided to use sodium iodide detectors, resolving the complex gamma spectra thus obtained by the use of least-squares analyses.
We are using a slightly modified form of the Alpha-M computer program developed at Oak Ridge National Laboratory by Schonfeld, and the TVA computing center at Chattanooga runs the program for us. We have also developed capabilities using germanium gamma detectors.
The laboratory recently completed detailed studies on both the germanium (lithium) and the sodium iodide (thallium) least-squares gamma analysis systems. These studies show the advantages and limitations of each system, and the application of each system to the analysis of environmental samples. By using the advantages that each system offers, we have developed a balanced approach to gamma-ray analyses.
Confirmatory Measurements of Radionuclide Concentrations in Power Reactor Effluents
Authors: Gibson GT , Pagliaro JA 
Published: March 2009

The U. S. Nuclear Regulatory Commission (NRC) conducts a radioactive waste system inspection program with nuclear power facility licensees. The confirmatory measurements portion of the program consists of a test of the licensee's measurements of radioactivity in actual or simulated plant effluent samples (liquid, off-gas, participate filter, and charcoal adsorber), comparing the licensee's measurements with those of the NRC reference laboratory.
The NRC has developed a computer data analysis system (CDAS) which performs comparisons of the analytical results of the licensee and NRC reference laboratory and which provides statistical analyses of licensee performance. Licensee ability to adequately identify and quantify radionuclides in plant effluents is thereby documented. Comparison of these analytical results is the basis for the NRC Confirmatory Measurement Inspection Program.
Experience with an Analytical Quality-Control Program
Authors: Harley JH 
Published: March 2009

Over the past few years there has been an increasing tendency to question the results of scientific work, including analytical measurements. There has always been some review by our scientific peers, but we are now finding that we must justify quality to the public as well. This is not unreasonable since they are usually paying for the work either as consumers or as taxpayers, and any analytical laboratory should be able to stand behind the quality of its work.
The Environmental Measurements Laboratory (formerly the Health and Safety Laboratory) has had a formal quality-control program since 1960. This has been used for both internal analyses and for measurements performed under contract to commercial laboratories. The program has consisted of submitting from 10 to 15 percent of the samples in the form of standards, blanks, or blind duplicates. In almost all cases, the analyst is not aware of which samples are the quality-control samples. The results of this program are published annually in our Environmental Quarterly so that those that use our data can recognize the quality of the analytical work.
The benefits of this program have been an increase in confidence by the data users and a sense of pride in the analyst for having produced useful measurements. In addition, problems of calibration drift, operator performance, and inadequacy of methods can be recognized at a reasonably early stage and the necessary corrective action taken.
The paper includes extensive data presentations covering-quality control samples, calibrations, and participation in intercomparisons.
The DOE-OES-EML Quality Assurance Program
Authors: Sanderson CG 
Published: March 2009

Contractor laboratories handling radioactive materials for the U.S. Department of Energy (DOE) are required to monitor the environmental exposure and publish annual reports for the Division of Operational and Environmental Safety (OES). In order to determine the validity of the data contained in these reports the Environmental Measurements Laboratory (EML) was requested to develop, coordinate, and conduct an Environmental Quality Assurance Program (QAP).
There are four major phases to the DOE-OES-EML Quality Assurance Program: Sample collection and preparation, sample analyses at EML, quarterly sample distribution, and reporting the data returned by the participants.
This paper discusses the various phases of the QAP and briefly discusses the data reported during the first year of the program.
Minority Carrier Lifetime Characteristics in Semiconductor Silicon—An Overview
Authors: Vieweg-Gutberlet FG 
Published: March 2009

For the characterization of the starting silicon material lifetime measurements were carried out very early in silicon technology. A wide variety of measurement techniques was developed, such as diffusion length measurement, the photocurrent method, and the widely used photoconductivity decay method (PCD).
As silicon technology developed, lifetime measurements for the characterization of the starting (ingot) material became less important because of the increase in the perfection and purity of the silicon. In turn, lifetime measurements for in-process control of the device fabrication became more and more important.
For the characterization of neutron transmutation doped (NTD) silicon, lifetime measurements on the ingot material have become important again because of the dependence of the lifetime on the thermal annealing process subsequent to the irradiation.
Influence of Crystal Defects on the Generation Lifetime of Minority Carriers in Silicon
Authors: Eder A , Werner C 
Published: March 2009

Measurements of generation- lifetime inhomogeneities were performed on wafers containing crystal defects. The lateral resolution was 250 μm, so that the influence of single defects could be seen.
The authors show that both dislocations and oxidation-induced stacking faults may severely reduce lifetime in a very small region. Moreover, examples are presented where lifetime was improved in the vicinity of the defects because of some sort of gettering action. Finally, it is shown that lifetime inhomogeneities can be avoided by performing a preoxidational back-side gettering (POGO) procedure.
Minority Carrier Lifetime Profile Measurements by Use of the Photocurrent Technique
Authors: Reichl H , Ruge I , Eichinger P , Müller JL 
Published: March 2009

Using the photocurrent technique, lifetime measurements on electron irradiated silicon were carried out. The electron energy was varied between 0.5 and 2.5 MeV. The doses were in the range of 5 × 1013 cm−2 to 1016 cm−2. The measured lifetime distribution over the wafer showed a decrease of lifetime from about 50 μs outside to less than 0.5 μs within the irradiated area for an electron energy of 0.5 MeV. For doses increasing from 5 × 1013 cm−2 to 1016 cm−2, a decrease in lifetime outside the irradiated area was also observed.
It was shown that the determination of lifetimes by use of the photocurrent method is restricted to layers thicker than 2.5 times the diffusion length. However, if light with a short penetration depth is used, the travel time of the minority carriers from the illuminated side of the specimen to the Schottky contact can be measured, and the measurement can be extended to thinner specimens. The influence of the absorption coefficient and the surface recombination velocity are discussed.
The measurements were carried out on a silicon wafer with a diffusion length comparable to the thickness of the specimen.
A Contactless Method of p-n Junction Leakage Testing and Comparison of Associated Data with Contact-Determined Leakage
Authors: Verkuil RL , Pak MS 
Published: March 2009

A contactless p-n junction leakage measurement method is described, which uses specialized very-high-frequency oscillator circuitry. This circuitry utilizes the eddy current loading effect, via inductive coupling, in order to determine the leakage-dependent decay time of the photoinduced voltage across the diffused p-n junctions in a silicon wafer.
The contactless measurement is made under low forward bias conditions (≤ 10 mV), in such a way that this measurement and the contacting reverse leakage, measured at 100 mV, will both be functions of generation-recombination processes in the junction depletion region. Detectable signals were made possible by low-noise circuitry and by the increase in junction eddy currents from induced voltages across the diffused regions.
The following model was derived from basic circuit theory, which relates the contactless decay time measurement, τ, to the conventional contacting reverse leakage, J0 J0=CkT∕qτ
where
J0 = reverse leakage, A/cm2,
C = junction capacitance, F/cm2,
τ = decay time, s, and
kT/q = 26 mV at T = 300 K.
Good agreement was obtained between experiment and theory. The examined range was four orders of magnitude in leakage current.
Multiple Water Drop Impact Damage in Layered Infrared Transparent Materials
Authors: Peterson TL 
Published: March 2009

The influence of materials and construction variables on the rain erosion behavior of layered infrared window materials has been investigated at 210 m/s in the simulated rain environment (1.8 mm drop diameter, 2.5 cm/h rainfall rate) of the Air Force Materials Laboratory rotating-arm apparatus.
Outer-layer materials included chemical vapor deposited (CVD) zinc sulfide, hotpressed zinc sulfide, and CVD gallium arsenide. These materials were either deposited directly onto CVD zinc selenide substrates or adhesively bonded to the zinc selenide.
In general, damage mechanisms and relative rates of degradation were predictable from studies of the erosion behavior of homogeneous specimens. The effect of layer thickness on erosion behavior was determined for outer layers of CVD zinc sulfide. For outer layers thicker than approximately 1.0 mm, damage in the layered specimens was comparable to that in homogeneous CVD zinc sulfide specimens. The amount of multiple impact damage in layers thinner than 1.0 mm compared with that in thicker layers depended upon the technique of fabrication. Damage was more severe for thinner layers bonded to zinc selenide but was somewhat reduced for thinner layers deposited directly on zinc selenide.
The effect of grain size on erosion resistance was demonstrated by comparison of the behavior of layers of CVD gallium arsenide bonded to zinc selenide with that of gradient-freeze grown gallium arsenide. The CVD material was more resistant to impact damage because of its much smaller grain size.
Thin films deposited on zinc sulfide and gallium arsenide as antireflection coatings were susceptible to removal by drop impacts and the subsequent radial outward flow of water away from the impact site. However, more durable antireflection coatings on zinc sulfide have been developed.
A Study of Erosion by High-Pressure Cavitating and Noncavitating Waterjets
Authors: Vijay MM , Brierley WH 
Published: March 2009

A study was made of erosion by high-pressure noncavitating and cavitating waterjets issuing from five different arrangements of nozzles, consisting of (A) jet in air, (B) submerged jet, (C) jet surrounded by another of lower velocity, (D) jet from long nozzles, and (E) jet from a nozzle containing a cylindrical body insert. The purpose was to evaluate the two methods of erosion for jet cutting applications.
Simple visual examination of the craters on specimens of copper showed distinct type (size, shape, depth, etc.) of erosion. However, microscopic examination did not reveal clearly any characteristics peculiar to cavitating or noncavitating jets.
Quantitative experimental results were obtained by measuring the mass loss of lead specimens as a function of time of exposure for the conditions where either the nozzle pressure or the standoff distance was held constant. By comparing the different arrangements on the basis of material loss, it is concluded that Arrangement B performed best for all periods of exposure and standoff distances followed by Arrangement C for short periods of exposure, smaller standoff distance, and for certain flow conditions.
A Finite-Element Analysis of Stable Crack Growth—I
Authors: Nakagaki M , Chen WH , Atluri SN 
Published: March 2009

A finite-element methodology is developed to study the phenomenon of stable crack growth in two-dimensional problems involving ductile materials. Crack growth is simulated by (1) the translation in steps, of a core of sector elements, with embedded singularities of Hutchinson-Rice-Rosengran type by an arbitrary amount, Δa in each step, in the desired direction; (2) reinterpolation of the requisite data in the new finite-element mesh; and (3) incremental relaxation of tractions in order to create a new crack face of length Δa. Steps 1 and 2 were followed by corrective equilibrium-check iterations. A finite deformation analysis based on the incremental updated Lagrangian formulation of the hybrid-displacement finite-element method is used.
The present procedure is used to simulate available experimental data on stable crack growth, and thus to study the variation during crack growth of certain physical parameters that may govern the stability of such growth and the subsequent onset of rapid fracture. Attention is focused in this study on the following parameters: G*Δ, the energy release to the crack tip per unit crack growth, for growth in finite steps Δa, calculated from global energy balance considerations; GpzΔ the energy release to a finite “process zone” near the crack tip per unit crack growth, for growth in finite steps Δa, calculated again from global energy balance considerations; and the crack opening angles. However, the work reported here is limited to the first phase of our study, that is, to simulation of available experimental data.
A Comparison of Elastic-Plastic Fracture Parameters in Biaxial Stress States
Authors: Miller KJ , Kfouri AP 
Published: March 2009

Parameters used in fracture predictions in elastic-plastic materials will differ from those used when the material is elastic. However, the first set of parameters may reduce to the latter in the limiting case of brittle behavior involving minimal plasticity. Analyses of the stress and plastic strain fields in the region of the crack tip and evaluations of energy release rates are therefore relevant to studies on fracture processes in engineering materials. It is becoming generally recognized that more than one parameter is needed in the formulation of a realistic fracture criterion applicable to elastic-plastic materials. In particular, such a criterion must take into account the possible biaxial nature of the applied stress.
This paper presents some of the results of extensive elastic-plastic finite-element analyses on a center-cracked plate. Information is provided, and comparisons made, on such features as crack-tip plastic zone sizes, intensities of plastic strain near the tip, the major principal stress in the crack-tip region, crack opening displacements, values of the J contour integral, and crack separation energy rates GΔ—all corresponding to different biaxial stress states.
An Evaluation of Elastic-Plastic Methods Applied to Crack Growth Resistance Measurements
Authors: McCabe DE , Landes JD 
Published: March 2009

Information from tests on blunt notched specimens for J-integral calibration by conventional J = -1/B ∂U/∂a analysis is used to evaluate the significance of plastic zone adjustment to physical crack length in crack growth resistance, KR, calculations. Secants are drawn to load versus displacement test records to determine plastic zone adjusted crack lengths. Tests on three specimen geometries [compact specimen (CS), single-edge notched bend (SENB), and center-notched tension (CNT)] and on two materials (HY130 steel and 2024 aluminum) have shown that this procedure develops KR values that are equivalent to J. This demonstration opens possibilities that J can now be applied to cases where there is subcritical crack growth such as in R-curve work, KIscc, and possibly in creep cracking studies. Also, this provides a simplified method for computing J experimentally on complex geometries for which elastic KI solutions are available.
Alternative J computational procedures are compared. These include J by a Ramberg-Osgood work-hardening law fit to load-displacement records, and J by area approximation methods. The Ramberg-Osgood modeling appeared to work reasonably well in tests on compact specimens but was found to be unreliable on SENB and CNT specimens and therefore is not recommended. With no stable crack propagation, the area approximation procedures for J determination produce reasonably accurate estimates of J as might have been anticipated from past experience. Tests on the compact specimen geometry required a Merkle-Corten correction procedure which worked well on large crack aspect ratios, where a/w ⩾ 0.5, but tended to overcorrect for short cracks, giving nonconservative results.
Computer Interactive JIc of Testing Navy Alloys
Authors: Joyce JA , Gudas JP 
Published: March 2009

A computer interactive unloading compliance single-specimen JIc test procedure has been developed. This procedure utilizes an on-line minicomputer to analyze digitized load-displacement data during testing. Unique values of JI and crack length are determined from compliance measurement on short unloadings along the load displacement record. The test procedure is presented in detail and analysis procedures are discussed.
Three tasks which demonstrate the validity and utility of the computer interactive test method are discussed. Results for single-specimen and multiple-specimen tests are presented for HY 130, 10Ni steel, 17-4PH steel, Ti-7Al-2Cb-1Ta, and Ti-6Al-4V which show close correspondence between the two methods. Tests on 17-4PH steel compact tension specimens with various thicknesses and crack lengths are summarized and dimensional effects on JIc and the J-Δa resistance curve slopes are discussed. Finally, tests on HY 130 specimens with various notch root radii demonstrate effects of notch acuity on JIc.