bluuebunny/crossref_metadata_2025_split huggingface dataset:
Current Practices in the Measurement of Oxygen Transmission Rates of Packaging Films Under Humid Conditions
Authors: Pike L 
Published: March 2009

The techniques being used to measure the oxygen transmission rates of packaging films under humid conditions are briefly described and their advantages and disadvantages discussed. The techniques consist of various methods of humidifying the gas streams used in the standard methods for dry gas transmission rate measurements and the controlled humidity “sandwich” method. The new modern controls “H-System,” which was designed especially for this purpose, is also described.
One must choose from the available techniques and equipment based upon the needs and funds available. Only very limited data are available for comparison of the techniques, so accurate statements about precision still cannot be made.
Evaluation of Cure and Durability Aspects of Building Sealants
Authors: Beech J , Beasley J 
Published: March 2009

Durability characteristics of sealants have been assessed by measuring the changes in certain key properties (“performance indices”) after exposure of specimens to natural and to artificial weathering. A major problem in such assessments is the long duration of the cure processes of sealants after specimens are made up: in some cases these extend to 12 months or longer, during which periods continuing changes in sealant properties are observed.
This paper reports the results of a controlled study which attempts to distinguish between those changes in properties due to the continuing cure process, and those caused by changes in the sealant due to exposure to various environments which simulate the effects of weather. The latter included laboratory regimes in which the sealant samples were exposed to elevated temperature (70°C), both with and without UV(B) radiation; to artificial weathering including UV(B) radiation and water condensation; and exposure to weather in the UK, for up to 12 months.
The study involves two phases, in the first of which, reported here, freshly-prepared sealant specimens were exposed to ageing or to weather before tensile testing. In the second phase the same procedures were followed using specimens which had first been stored under standard conditions in the laboratory for 12 months.
Some results of the first phase of this study of cure and durability characteristics are given in this paper, and discussed in relation to the development of test methods for the assessment of the durability of sealants. Modulus values measured on sealant samples after exposure to artificial weathering and to heat ageing in the laboratory show highly-significant correlations with data from naturally-weathered samples.
Adhesion of Silicone Sealants to Organic-Coated Aluminium
Authors: Gutowski VWS , Russell L , Cerra A 
Published: March 2009

The integrity of a structurally glazed building envelope depends on the strength of adhesion at several interfaces, e.g. glass- glass coating, glass coating-silicone sealant, silicon sealant-substrate coating, substrate coating-primer, primer-substrate.
Frequently, the frame and cladding are aluminium alloys which are either anodised or finished with an organic coating to satisfy aesthetic and/or long-term corrosion resistance requirements.
In this paper, the mechanism of adhesion between organic-coated aluminium and silicone sealants is analysed. The sealants investigated are neutral-, alkaline-, and acid-cured, 1-part RTV silicones as well as 2-part RTV silicones, all commercially available. The organic coatings investigated are powder and wet-coated polyester, PVF2 (polyvinylidene flouride), acrylic and siliconised finishes, also all commercially available products.
It is shown that the strength of adhesion between any silicone sealant and the organic-coated substrate, as well as the extent of adhesive failure, depend on the substrate surface properties as quantified by the non-dispersive component of the substrate surface energy, γn-d. A typical relationship is shown to exist for strength v. γn-d and [%] adhesive failure v. γn-d.
Finally it is shown that the organic-coated substrates used in structural glazing can be assessed for their potential bondability with silicone sealants by determining the non-dispersive component of their surface energy. This technique is described in detail in this paper.
Deep Space Network 70-Meter Antenna Elevation Bearing Failure Investigation
Authors: DiGiorgio AS , Hsieh C 
Published: March 2009

Antennas for the United States Deep Space Network (DSN) are vital to the success of the space program in providing tracking and communication with deep space probes. The three 70-meter antennas, located in California, Spain, and Australia, are the largest and most important link of the DSN network capability. These antennas were originally constructed at 64 meters in diameter, but were subsequently modified to 70-meter diameter to support the Neptune and Uranus encounters by the Voyager spacecraft. An increase in load on the supporting bearings accompanied this modification. It was determined that the bearings possessed the capacity to support this additional load; however, the load was not uniformly distributed.
One of the elevation bearings on the antenna in Spain collapsed on December 13, 1989. This bearing functioned on the 70-meter antenna over an 18 year period. Four SKF 231/600 CAK C1 W33 SRB bearings support the DSN antenna assemblies which rotate very slowly over 160° once or twice daily. Bearing rolling contact components were manufactured from AISI 52100 steel. Rolling elements were produced with axially through-bore holes to facilitate the heat treat process. Failure investigation established that fatigue cracks initiated at the surfaces of center holes, progressed to fracture which led to lockup and culminated in overload of associated bearing components. Due to advancements in material development since the 1970s, solid rollers may be satisfactorily produced without center holes which can introduce sources for stress risers.
Antenna operation was promptly restored by replacing the damaged bearing with a spare. Load equalization and nondestructive inspection of the remaining bearings were conducted. Fracture mechanics analysis was performed to estimate the remaining life of the bearings. Due to the critical nature of the DSN antennas, a recommendation was made to replace existing bearings with current state of the art solid roller bearings.
The Effect of Conversion Coated and Plated Components on the Corrosion of Cobalt Alloy Magnetic Disks
Authors: Goodson K , Cormia R 
Published: March 2009

Common disk drive components with chromate conversion coatings or electroless nickel platings were analyzed by ion chromatography for residual levels of Cl-, F-, SO42-, and NO3-. Extraction with boiling DI water revealed levels up to several hundred ng/cm2 for these anions. When these components were placed 2 mm under a suspended cobalt-nickel-phosphorous disk in an environmental chamber at 55°C/85% RH, corrosion of the cobalt disk occurred directly over the chromated component when the total level of anions was greater than 200 ng/cm2. This accelerated corrosion did not occur in a 120-h test when the level was less than 50 ng/cm2. The amount of corrosion was found to be dependent on the separation distance between the disk and the chromated component.
Surface analysis of the disk corrosion area exposed to a chromate conversion coating showed NiO, CoO, and an increased concentration of chlorine.
The Influence of a Magnetic Field on Corrosion of Steel
Authors: Yee S-SW , Bradford SA 
Published: March 2009

Magnetic influence has been suspected or reported as a contributing factor in many cases of metallic corrosion near magnetic sources. This study has examined the corrosion behavior of a plain-carbon steel in a 3% sodium chloride (NaCl) solution within and without magnetic fields up to 0.245 T at room temperature. Anode and cathode corrosion half-cells were separated so that the magnetic effect on each electrode reaction could be studied by itself. Direction of the field with respect to the electrode surfaces was also varied.
Cathodic polarization of steel is not affected by a magnetic field; neither is anodic polarization up to a current density of approximately 10 mA/cm2. It was also found by cyclic polarization that a magnetic field does not affect the susceptibility of the steel to localized attack in a 3% NaCl solution. However, at extreme corrosion rates (more than 24 cm/year), an applied magnetic field of 0.245 T causes a maximum change of 2.7% in the anodic dissolution rate.
Fracture Mechanics Parameters for Small Fatigue Cracks
Authors: Newman JC 
Published: March 2009

The small-crack anomaly, where small cracks tend to grow either faster or slower than large cracks when compared on the basis of linear-elastic stress-intensity factors, has been shown to be significant for some materials and loading conditions. Conventional linear-elastic analyses of small cracks in homogeneous bodies are considered inadequate because of microstructural influences not accounted for in the stress-intensity factor and because of thenonlinear stress-strain behavior at notches and in the crack-front region. In this paper, plasticity effects and crack-closure transients are reviewed and investigated.
This paper presents a review of some common small-crack test specimens, the underlying causes of the small-crack effect, and the fracture-mechanics parameters that have been used to correlate or predict their growth behavior. Although microstructural features are important in the initiation and growth of small cracks, this review concentrates on continuum mechanics concepts and on the nonlinear behavior of small cracks. The paper reviews some stress-intensity factor solutions for small-crack test specimens and develops some simple elastic-plastic J integral and cyclic J integral expressions that include the influence of crack closure. These parameters were applied to small-crack growth data on two aluminum alloys, and a fatigue life prediction methodology is demonstrated. For these materials, the crack-closure transient from the plastic wake was found to be the major factor in causing the small-crack effect. Plasticity effects on small-crack growth rates were found to be small in the near threshold region, in that the elastic stress-intensity factor range and the equivalent value from the cyclic J integral gave nearly the same value.
Simulation of Short Crack and Other Low Closure Loading Conditions Utilizing Constant Kmax ΔK-Decreasing Fatigue Crack Growth Procedures
Authors: Hertzberg R , Herman WA , Clark T , Jaccard R 
Published: March 2009

Small cracks can grow at ΔK levels previously thought safe (that is, ΔK &lt; ΔKΔKth). It follows that ΔKth values, measured according to ASTM Test Method for Measurements of Fatigue Crack Growth Rates (E 647) procedures and associated with long-crack test specimens, may lead to nonconservative lifetime estimates of a component that contains very small cracks. One major reason for this discrepancy may be traced to the fact that different closure levels are found at the same applied ΔK level for long and short cracks, respectively. Much effort has been given to the generation of conservative fatigue crack propagation (FCP) data through the development of large quantities of short-crack data. Unfortunately, the generation of these data are time-consuming, tedious, and subject to considerable amounts of scatter.
An alternative test method, based on the use of standard-sized samples and employing established automated data acquisition procedures, has been identified. This method is based on maintaining a constant maximum stress intensity level (Kcmax) during the ΔK-decreasing test procedure. By maintaining a constant Kmax value, mean stress and associated R levels are found to increase markedly as ΔK decreases. The development of these high levels of mean stress and R ratios produces a long crack with negligible crack closure, which provides an upper bound estimate for the behavior of short cracks. Kcmax FCP data for several aluminum, iron, and nickel-based alloys have been generated and demonstrate the utility of the Kcmax test methodology as a simple and convenient means to obtain upper bound estimates of short-crack behavior in these structural alloy systems.
The Cumulative Fatigue Damage Behavior of MAR-M 247 in Air and High-Pressure Hydrogen
Authors: McGaw MA , Kalluri S , Moore D , Heine J 
Published: March 2009

The cumulative fatigue damage behavior of the cast nickel-base superalloy, MAR-M 247 (in a fine grain form), was characterized experimentally at room temperature in ambient air and in high-pressure gaseous hydrogen. The material was first characterized in simple fatigue, consisting of fully reversed strain- and load-controlled axial fatigue tests. These data were used to establish the reference life behavior for use in the cumulative fatigue experiments. The principal tool used to study the cumulative damage behavior was the two-level loading test (single-block) wherein low-cycle fatigue loading is applied initially to the specimen for various low-cycle fatigue life fractions, and the specimen is subsequently cycled under high-cycle fatigue conditions to failure. MAR-M 247 was found to exhibit a strongly nonlinear cumulative interaction behavior, with the remaining high-cycle fatigue life capability in the second load level reduced by as much as a factor of 30 over results predicted from a linear damage rule. The Damage Curve Approach of Manson and Halford was used to predict this nonlinear cumulative behavior.
Similar experiments were performed at room temperature in a high-pressure gaseous hydrogen environment to assess the cumulative damage behavior and applicability of the Damage Curve Approach under differing environmental conditions. To study the applicability to more general loading cases, multi-block loading experiments were performed in air, in which each block consisted of both low-cycle and high-cycle fatigue cycling in prescribed amounts, ranging from one low-cycle fatigue cycle plus a fixed number of high-cycle fatigue cycles, to many low-cycle fatigue cycles plus a fixed number of high-cycle fatigue cycles. This basic loading block was then repeated until failure of the specimen. The results of these experiments and the predictions using the Damage Curve Approach are presented and discussed.
Novel Methodology for Fatigue Lifetime Prediction
Authors: Puskar A 
Published: March 2009

A unique fatigue lifetime equation offers the possibility of predicting residual fatigue lifetime of a material. Derivation of this lifetime equation is based on a correlation between the total and plastic strain amplitude during cyclic loading. A ratio determined as the reciprocal value of the elasticity modulus degradation is evaluated from the continuous measurements of the specimen resonance frequency in a resonance testing machine. For successful application of this procedure, coefficients and exponents for a fatigue curve, Coffin/Manson curve and cyclic stress-strain curve, or coefficient and exponent for the new fatigue lifetime equation are needed. This new equation and the well-known equations of cyclic plastic response are fully compatible. Measurements of dynamic elastic (secant) modulus of a virgin specimen and of a specimen after previous cyclic loading then provide an opportunity to evaluate the residual fatigue life.
The verification of the proposed procedure was performed using a carbon steel with 0.485 mass % carbon at a test frequency of 20.2 kHz, using three different rates of increase for the total strain amplitude before starting ordinary fatigue testing (loading ramps).
Impact of U.S. NRC Reactor Vessel Embrittlement Research on Regulation of Nuclear Power Plants
Authors: Serpan CZ 
Published: March 2009

The embrittlement of nuclear reactor pressure vessels caused by neutron radiation is the chief aging mechanism of these critical components. It is so critical to safe operation of reactors that the U.S. Nuclear Regulatory Commission (USNRC) and its predecessor, the Atomic Energy Commission, have spent millions of dollars over the past three decades to document the effects. Furthermore, USNRC regulations and associated regulatory documents derived from that research basis now provide guidance on establishing operational conditions to assure that the pressure vessels of U.S. reactors will behave in a ductile manner, and that vessel materials will exhibit a sufficiently high resistance to ductile fracture.
The regulations and regulatory guidance that pertain to assuring the integrity of U.S. reactor pressure vessels are described and related to the operational constraints. Areas where additional data are needed, and where the analyses may be improved are noted and described. Finally, a prognosis is offered for future improvements in the technical basis for U.S. regulations.
Revision of Neutron Dosimetry for the Loviisa WER-440 Reactors: Principles and Application
Authors: Baers LB , Serén T0 
Published: March 2009

A comprehensive re-evaluation of all neutron dosimetry results for the Loviisa reactors (WER-440, 2 units) started in 1992.
Revised and better validated neutron spectra, a refined semiem pirical approach utilizing the computer program PREVIEW [4], unified and up-dated nuclear data and refined and extended calibrations of the applied Liquid Scintillation Counter (LSC) for 93mNb activity measurements are applied. The kernel-based computer program PREVIEW makes it possible to take into account the detailed local irradiation history e.g. the influence of the calculated time-dependent axial flux changes during a cycle.
The main features of this re-evaluation are reported together with updated results for two IAEA-CRP surveillance chains (SC) denoted “4K” and “5K”.
The fluence (&gt;1 MeV) estimates increased by +16 to +20% and the dpa estimates by +24 to +27% as compared to previous results. The largest changes, about +20% in the &gt;1 MeV fluences, arose from the revised and better validated neutron spectra. The refined treatment in PREVIEW of time-dependent variations fin the axial flux distribution accounted for 0 to −5% in the fluence estimates based on 54Fe (0 to −16% for 58Co).
Nb, Fe, Ni, Ti and Cu dosimeters were used for validations of the calculated neutron spectra built into the PREVIEW kernel library.
The quality of the neutron fluence estimates could be signifi cantly improved by applying revised and better validated neutron spectrum shapes and by applying a refined semiempirical approach taking into account calculated axial flux changes during an operating cycle. The remaining significant uncertainties in the neutron spec trum shapes and cross sections emphasise the development and applica tion of additional and more reliable dosimeters for the lower fast neutron energies.
Special Dosimetry at Saint Laurent BL Mox-Loaded Unit
Authors: Bevilacqua A , Lloret R , Nimal JC , Zengh S , Rieg C 
Published: March 2009

A special highly instrumented surveillance capsule and dosimetry in the cavity along three generating lines were installed in the Electricité de France Saint Laurent Bl 900 MWe pressurized water reactor, and irradiated during the 1991–92 cycle. This instrumentation was presented at the Seventh ASTM-EURATOM Symposium in Strasbourg.
The reactor and cycle were chosen to be representative of balanced loading with mixed oxides UO2-PuO2 fuel (MOX), with the following objectives: -studying the effects of the MOX loading on the exposure of the capsule and vessel, -checking the disturbances of the axial distribution of the reaction rates of the dosimeters, caused by the barrel formers, -validation of the exposure calculations in the thickness of th vessel, -testing the Solid State Track Recorder technique compared with a dosimetry by activation in the cavity, -determining the maximum irradiation temperature of the capsule
Using the mean fission sources over the irradiation period, a TRIPOLI computation (with the ENDF-BVI library and the probability tables method) evaluates the measured parameters and the neutron spectra accompanied by their variance-covariance matrices, with a viev to adjusting these spectra.
The devices implemented are described. The instrumentation loading and unloading operations were performed successfully. The available results are given: MOX loading in the second periphery seems not to significantly change the exposure parameters, calculations slightly underestimate the reaction rates in the capsule and tend to overestimate them in the cavity.
Validation of Neutron Transport Calculations on Magnox Power Plant
Authors: Mossop JR , Thornton DA , Lewis TA 
Published: March 2009

This paper describes the validation of fast neutron transport calculations for Magnox RPVs operated by Nuclear Electric. The work compares calculated data, derived using the Monte Carlo code McBEND, with extensive plant measurements. Agreement is typically within ∼20%.
This level of agreement has been achieved using individual models for the top, side and bottom of each reactor in which almost explicit representation of all the major components was required. The modelling detail included the geometric effects of temperature and irradiation on reactor components as well as source data derived from reactor measurements and operating histories. Such effort is justified because the reduced uncertainty in the pressure vessel dose can be translated into increased operating margins and extended plant lifetimes.
“Concrete Benchmark” Experiment as Support to Ex-Vessel LWR Surveillance Dosimetry
Authors: Abderrahim HA , D‘hondt PJ , Risch P , Oeyen JB , Bioux P 
Published: March 2009

The analysis of DOEL-1 in-vessel and ex-vessel neutron dosimetry, using the DOT 3.5 Sn code coupled with the VITAMIN-C cross-section library, showed the same C/E values for different detectors at the surveillance capsule and the ex-vessel cavity positions. These results seem to be in contradiction with those obtained in several benchmark experiments (PCA, PSF, VENUS ...) that used the same computational tools. Indeed a strong decreasing radial trend of the C/E was observed, partly explained by the overestimation of the iron inelastic scattering. The flat trend seen in DOEL-1 could be explained by compensating errors in the calculation such as the backscattering due to the concrete walls outside the cavity. The “Concrete Benchmark” experiment has been designed to judge the ability of this calculational method to treat the backscattering.
This paper describes the “Concrete Benchmark” experiment, the measured and computed neutron dosimetry results and their comparison. This preliminary analysis seems to indicate an overestimation of the backscattering effect in the calculations.
Measurement and Analysis of Gamma-Ray Distributions in Kyoto University Critical Assembly, KUCA
Authors: Kimura I , Kagehira K , Sakurai Y , Kimura J , Kanno I , Sato T , Shiroya S , Kanda K 
Published: March 2009

Gamma-ray distributions in an undermoderated core of the Kyoto University Critical Assembly, KUCA-B, were measured with four thermoluminescence dosimeters (TLDs), magnesium, strontium and barium orthosilicate (Mg2SiO4(Tb), Sr2SiO4(Tb) and Ba2SiO4(Tb)); and calcium sulfate (CaSO4(Tm)). In advance of the measurements, the response of these TLDs to gamma-rays was calibrated with a 60Co source and that of Mg2SiO4(Tb) to neutrons was tested.
The neutron and gamma-ray flux distributions in the core of KUCA were simultaneously calculated by a transport code ANISN-JR, using a combined cross section set generated by RADHEAT-V3. The distribution of the gamma-rays from fission products was independently calculated. In order to obtain the absorbed dose of each TLD, the following three components were summed up: (1) prompt gamma-rays, (2) fission product gamma-rays and (3) neutrons. All data were normalized by the reaction rate of 58Ni(n,p)58Co at the core center.
In general, the absolute values and the shape of the absorbed dose distribution measured with the four TLDs agree with the calculated ones very well. However the measured values in the reflector region with Sr2SiO4(Tb), Ba2SiO4(Tb) and CaSO4(Tm) are considerably larger than the calculated results.