bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of the Lower Temperature Limit of Void Swelling of Stainless Steels at PWR-Relevant Displacement Rates
Authors: Porollo SI , Konobeev YV , Dvoriashin AM , Krigan VM , Garner FA 
Published: April 2008

Recent studies associated with light water reactors (LWR) in both the USA and Russia have raised the question of void swelling in austenitic components of core internals. One question of particular interest is the range of temperatures over which voids can develop, especially the lowest temperature. To address this question a flow restrictor component manufactured from annealed X18H9T was removed from the reflector region of the BN-350 fast reactor, located in Kazakhstan. During operation this component spanned temperatures and dpa rates of direct interest to pressurized water reactors (PWRs) in the West and VVERs in Russia. This steel is analogous to AISI 321 and is used in Russian reactors for applications where AISI 304 would be used in the West and in Japan.
This component was sectioned on a very fine scale to determine in what range of conditions voids existed. Microstructural data were obtained for 157 separate locations, with 111 specimens showing voids over the relevant range of temperatures and displacement rates, allowing construction of a parametric map of swelling with temperature, dpa and dpa rate. These data show that swelling at doses as high as ∼50 dpa persists down to ∼306°C for dose rates in the range 0.11 × 10-7 to 1.6 × 10-7dpa/sec. Since the helium generation rate is rather low in the spectral environment of the flow restrictor, the early onset of swelling is attributed primarily to the lower displacement rate, a conclusion supported by a number of other experimental studies.
Dependence of Maximum Swelling Temperature on Damage Dose in Cold Worked 16Cr-15Ni-2Mo-1Mn Cladding Irradiated in BN-600
Authors: Kozlov AV , Portnykh IA , Bryushkova SV , Kinev EA 
Published: April 2008

The experimental data comprising more than 1800 data points on swelling of fuel pin cladding specimens of cold worked austenitic steel 16Cr-15Ni-2Mo-1Mn irradiated in the BN-600 reactor are described by the equation S = Rs∙(D-D0)∙(1-exp(-p(D-D0))). Where S = swelling; D = damage dose; D0, p and Rs are parameters depending on irradiation temperature and damage dose rate.
The parameters of the equation were obtained at 40–90 dpa in the temperature range of 400 – 600 °C. Their dependencies on neutron irradiation temperature and radiation damage rate were then examined.
The dependence of swelling on neutron irradiation temperature for different values of damage dose was calculated using the derived temperature dependencies of the equation parameters. The temperature at which maximum swelling is observed was shown to increase with increasing dose in the selected model. An overview of the swelling temperature dependence on changes in the character of the equation parameters was also conducted.
Irradiation Creep and Swelling of Russian Ferritic-Martensitic Steels Irradiated to Very High Exposures in the BN-350 Fast Reactor at 305–335°C
Authors: Konobeev YV , Dvoriashin AM , Porollo SI , Shulepin SV , Budylkin NI , Mironova EG , Garner FA 
Published: April 2008

Russian ferritic/martensitic (F/M) steels EP-450, EP-852, and EP-823 were irradiated in the BN-350 fast reactor in the form of gas-pressurized creep tubes. The first steel is used in Russia for hexagonal wrappers in fast reactors. The other steels were developed for compatibility with Pb-Bi coolants and serve to enhance our understanding of the general behavior of this class of steels.
In an earlier paper we published data on irradiation creep of EP-450 and EP-823 at temperatures between 390–520°C, with dpa levels ranging from 20–60 dpa. In the current paper, new data on the irradiation creep and swelling of EP-450 and EP-852 at temperatures between 305–335°C and doses ranging from 61–89 dpa are presented. Where comparisons are possible, it appears that these steels exhibit behavior that is very consistent with that of Western steels. Swelling is relatively low at high neutron exposure and confined to temperatures &lt; 420°C, but it may be camouflaged somewhat by precipitation-related densification. These irradiation creep studies confirm that the creep compliance of F/M steels is about one-half that of austenitic steels.
Inter-Granular Phosphorus Segregation in Ferritic Steels
Authors: Faulkner RG , Flewitt PEJ , Lu Z 
Published: April 2008

Progress in modeling irradiation-assisted non-equilibrium and equilibrium inter-granular segregation in steels is discussed. Solute drag and rate theory models for non-equilibrium segregation are compared. Reference is made to recent MD simulation work on irradiated grain boundaries in alpha iron.
Predictions of the models for phosphorus inter-granular segregation are compared with several recently published experimental data from pressure vessel steels. These are as follows. • A summary of results from field emission gun scanning transmission electron microscopy (FEGSTEM) and Auger Electron Spectrometry (AES) for a variety of dose and dose rate conditions. • A systematic survey of results from variable dose rate experiments. • Results from a recent systematic data set produced from C-Mn steel submerged arc welds.
The fits of the predictions to the observations show the strong influence of site competition from carbon on the final phosphorus inter-granular segregation level.
The Prediction of Fatigue Life Distributions from the Analysis of Plain Specimen Data
Authors: Shepherd DP 
Published: April 2008

For any structurally critical component subject to fatigue, the safety of the structure depends on an accurate prediction of the life under this failure mode. However, in such circumstances it is insufficient to consider only the mean behavior of the material. To ensure structural integrity, a model for the distribution of life to failure is required, which will allow lives to be assessed relative to acceptable safety levels.
In previous work, a methodology for deriving fatigue life estimates for arbitrary specimen and component geometries from plain specimen data has been developed [4]. The methodology is based on a procedure for developing a model for the initiation behavior of the material from the specimen data and for applying this to an arbitrary material geometry or stress field. In the current paper, this method is further developed to allow for the associated distribution of fatigue lives to be calculated. This involves direct consideration of the statistical relationship between crack initiation and crack propagation, so that the distribution of initiation lives can be derived accurately. However, incorporating these considerations directly into the methodology reveals some inconsistencies in the formulation of the original model. These relate to the fact that, at high stresses, the specimens will fail in tension rather than classical fracture, thus altering the interpretation of the data. It is shown that a more robust model can be developed, but only by including the distribution of tensile strength as an additional variable, and by considering the statistical relationship between this and the other fundamental variables.
The methodology which arises from the incorporation of these considerations into the basic calculation scheme is then developed, including a means for estimating the distribution of life to failure at all points on the stress against cyclic life curve.
Preliminary Results of the United States Nuclear Regulatory Commission's Pressurized Thermal Shock Rule Reevaluation Project
Authors: Dickson TL , Williams PT , Bass BR , Kirk MT 
Published: April 2008

The current federal regulations to insure that nuclear reactor pressure vessels (RPVs) maintain their structural integrity when subjected to transients such as pressurized thermal shock (PTS) events were derived from computational models developed in the early to mid-1980s. Since that time, there have been advancements in relevant technologies associated with the physics of PTS events that impact RPV integrity assessment. Preliminary studies performed in 1999 suggested that application of an improved technology could reduce the conservatism in the current regulations while continuing to provide reasonable assurance of adequate protection to public health and safety. A relaxation of PTS regulations could have profound implications for plant license-extension considerations. Based on the above, the United States Nuclear Regulatory Commission (USNRC) initiated in 1999 a program to re-evaluate the current PTS regulations within the framework established by modem probabilistic risk assessment techniques.As part of the USNRC PTS project, improved computational models have evolved through interactions between experts in the relevant disciplines of thermal hydraulics, probabilistic risk assessment, human reliability analysis, materials embrittlement effects on fracture toughness (crack initiation and arrest), fracture mechanics methodology, and fabrication-induced flaw characterization. The experts have been from the NRC staff, their contractors, and representatives from the nuclear industry. These improved models have been implemented into the FAVOR (Fracture Analysis of Vessels: Oak Ridge) computer code which is an applications tool for performing risk-informed structural integrity evaluations of embrittled RPVs subjected to transient thermal-hydraulic loading conditions.Recently, the FAVOR code was applied to a domestic commercial pressurized water reactor to evaluate the adequacy of the current regulations and to determine if a technical basis can be established to support a change in the current regulations. This paper gives an overview of the improved computational methodology and presents some results of the preliminary analyses.
Spectrum Editing for a Full-Scale Fatigue Test of a Fighter Aircraft Wing with Buffet Loading
Authors: Hewitt RL , Weiss JP , Nor PK 
Published: April 2008

This paper describes the spectrum editing techniques that were used to derive the test spectrum for the full-scale fatigue test of an F/A-18 wing that is currently underway at the Institute for Aerospace Research, National Research Council Canada. The derivation of the baseline spectrum and the truncation methodology are described, together with details of the validation process and the calculated effects of the truncation levels that were accepted.
Even with aggressive truncation, the test spectrum contained nearly 135 000 unique load conditions. Because of control system limitations and the time required to optimize and check the actuator loads for so many load conditions, a binning process was used to reduce the number of unique load conditions to less than 50 000. The process is detailed and the effects on the calculated life are discussed.
On the Causes of Deviation from the Palmgren-Miner Rule
Authors: McEvily AJ , Ishihara S , Endo M 
Published: April 2008

Based upon considerations of fatigue crack growth, explanations for the observation that the Palmgren-Miner damage summation often deviates from unity can be established. It is assumed that the fatigue lifetime is taken up entirely in fatigue crack propagation, that is the number of cycles spent in crack initiation is a negligibly small fraction of the total lifetime. This assumption permits the fatigue lifetime to be analyzed in terms of a basic constitutive relation for the rate of fatigue crack growth that is given by: dadN=A(ΔKeff−ΔKeffth)2 where a is the crack length, N is the number of cycles, A is a material-environmental constant, ΔKeff is the effective range of the stress intensity factor, i. e., Kmax - Kop, where Kmax is the maximum value of the stress intensity factor in a loading cycle, Kop is the stress intensity factor at the crack opening level, and ΔKeffth is the effective value of the stress intensity factor at the threshold level.
Three variable amplitude loading conditions are considered: two-step loading, multiple two-step loading, and overload and underload loading. In each case, the cause for deviation from a Palmgren-Miner damage summation of unity is clarified.
Numerical Modeling of Hydrodynamic Circulation and Cohesive Sediment Transport in Hartwell Lake, South Carolina/Georgia, USA
Authors: Elçi Ş , Work PA 
Published: April 2008

This paper describes numerical modeling of hydrodynamic circulation and cohesive sediment transport in Hartwell Lake, South Carolina/Georgia, a U.S. Army Corps of Engineers (USACE) hydropower and flood control reservoir. A U.S. Environmental Protection Agency (EPA) “Superfund” site is located on a tributary to the lake because of high concentrations of polychlorinated biphenyls (PCBs) in the lake sediments. The primary objective of this study involves prediction of depositional zones for sediments transported within the reservoir.
The EFDC (Environmental Fluid Dynamics Code) model developed by Hamrick (1996) is used to describe lake hydrodynamics and sediment fate. Historical records of wind and flow were used to determine frequencies of occurrence and representative conditions for prediction of long-term deposition zones for sediment transported by the flow.
Sensitivity of hydrodynamic processes to model parameters were investigated and wind was found to be the major force driving the circulation. Model results for cases with realistic long-term forcing indicated likely zones of sediment deposition, useful for mitigation of pollution problems as well as predictions of reservoir lifetime and development of maintenance schemes.
Promoted Ignition-Combustion Tests with Structured Aluminum Packings in Gaseous Oxygen with Argon or Nitrogen Dilution at 0.1 and 0.6 MPa
Authors: Meilinger M 
Published: April 2008

High-surface-area aluminum structured packings are finding a wide use in the cryogenic distillation of air. An experimental program was performed to determine the oxygen compatibility of commercial packings. In particular, the influence of pressure increase up to 0.6 MPa (6 bar absolute) and the effect of the replacement of nitrogen by argon as O2-diluting gas were investigated. Additionally, the impact of reducing the sheet thickness from 0.2 mm to 0.1 mm was tested.
The packing samples weighing 120–250 g were ignited on top by a 3 g thermite pill, resulting in a combustion channel which was either contained within the sample or passed through it. Incidents causing a noticeable downward widening of the channels were evaluated as “promoted combustion.” Typically, a promoted combustion occurred when the weight loss of corrugated sheet exceeded 10%.
The increase of pressure reduces the O2-threshold concentration for propagated combustion, as expected. Reducing the thickness of the sheets from 0.2 mm to 0.1 mm affects the O2-threshold concentration only slightly. A replacement of N2 by Ar as O2-diluting gas at 0.6 MPa shifts the O2-threshold somewhat beyond accuracy, but the extent of combustion in O2/N2-mixtures is much more substantial than in O2/Ar-mixtures. Thus a complete destruction of the Al-samples is reached in O2/N2-mixtures at much lower O2-concentrations.
Promoted Ignition-Combustion Behavior of Tubular Aluminum Samples in Liquid and Gaseous Oxygen Environments
Authors: Million JF , Zawierucha R , Samant AV 
Published: April 2008

Past literature has reported on the occurrence of violent energy releases (VER) involving either high surface area aluminum structured packing or brazed aluminum heat exchanger (BAHX) samples subjected to promoted ignition-combustion testing in liquid oxygen (LOX) environments. In each of these situations, both the aluminum packing samples and the BAHX specimens contained relatively thin sections of aluminum. The aluminum thickness ranged from 0.2 to 0.25 mm for the aluminum packing and the fin portion of “thin fin” BAHXs. Other “thick fin” BAHXs tested had nominal fin thicknesses ranging from 0.41 mm to 0.46 mm. Similar flammability data have not been reported for thick wall (4.1 mm), 3003 tubular aluminum heat exchanger material which may be used in LOX applications. The impetus for this program was to study the promoted-ignition combustion behavior of thick wall, tubular aluminum samples in various LOX environments using both a localized hydrocarbon promoter and uniformly dispersed hydrocarbon film. Tests were also conducted in various gaseous oxygen (GOX) environments using uniformly dispersed hydrocarbon films.
Promoted ignition-combustion tests were conducted on 4.1 mm thick aluminum ubes in LOX at pressures ranging from 101 kPa (0 psig) to 3551 kPa (500 psig). Tests in GOX were also conducted at 170 kPa (10 psig) and 274 kPa (25 psig). The resultant flammability characteristics of the aluminum tube specimens are compared to previously studied BAHX samples since both may be used in LOX applications.
Oxygen Hazards Analysis of Space Shuttle External Tank Gaseous Oxygen Pressurization System
Authors: Shoffstall MS , Stoltzfus JM 
Published: April 2008

In November 1999, White Sands Test Facility (WSTF) was informed of damage to a space shuttle oxygen system component that could release small metal particles into the gaseous oxygen (GOX) pressurization ystem of the external tank (ET). The WSTF oxygen hazards analysis group was requested by the NASA Johnson Space Center Propulsion and Fluids Systems Branch to evaluate the possible particle impact ignition hazards in the ET GOX pressurization system.
The ET GOX pressurization system uses high pressure bled from the oxygen urbopumps to provide ullage pressure for the liquid oxygen (LOX) tank. GOX enters the LOX tank through a diffuser attached to the interior of the LOX tank. The calculated GOX velocity at the diffuser outlet screen was approximately 51 m/s. According to published particle impact data, ignition often occurs at velocities of 45 m/s [1]. Therefore, NASA would have to either fly with a legitimate particle impact ignition risk or dismantle and clean the entire ET pressurization system before a subsequent flight.
Fortunately, WSTF located previously unpublished particle impact data that indicated the particulate potentially trapped in the ET pressurization system did not pose a legitimate ignition hazard. Based on these data, WSTF was able to assure JSC that there was not a legitimate particle impact ignition risk in this case. Therefore, this shuttle mission was safely accomplished without the delay or costs associated with disassembling the entire ET pressurization system.
In addition to presenting the rationale used to safely proceed with the shuttle mission, this paper also presents the previously unpublished data used to make these decisions.
Pipe Cleaning Using HFE Solvents and Assessment of Particle Contamination Found During Pipe Connection
Authors: Fletcher LE , Zugno R , Dimas J 
Published: April 2008

A pipe cleaning rig that flushes HFE™ solvents through pipes using a series of pressure vessels was developed and tested to determine whether the solvents and the equipment could clean aircraft oxygen system piping to the RAAF's specifications. The first aircraft pipes tested were 1/8 in. copper with either brass dome or cone-shaped end-fittings. To achieve 0.09 m2 (1 sq ft) of internal surface area, over 9 meters of pipe was required.
Results showed that HFE-7100™ was sufficient to remove most oils and greases, but one 600 mL flush with HFE-71DE™ was required to remove OM-15 hydraulic oil. However, initial particulate analysis showed the procedure did not meet the required particle specification. The reason was identified as particle contamination caused by the reconnection of pipes during the verification process. Once the verification method was modified to eliminate further connections, the particle specification was achieved.
This particle contamination was investigated further because this would occur during installation of these pipes in aircraft. The number of particles contaminating the wetted area was found to vary linearly with the number of reconnections, and between different fitting designs.
The Biomechanical Characteristics of Development-Age Hockey Players: Determining the Effects of Body Size on the Assessment of Skating Technique
Authors: McPherson MN , Wrigley A , Montelpare WJ 
Published: April 2008

Skating ability, and more specifically the ability to accelerate from a stationary position or change direction rapidly, is recognized as one of the most important skills in ice hockey. While coaches may use drills to compare skating performance between individuals, especially during player selection, few studies have identified the essential kinematic variables that contribute to the ability of development-age hockey players to accelerate over a specified distance. Previous research reported that the determination of performance and ultimately skating power could be related to specific biomechanical parameters, especially among developing hockey players. However, there is evidence to suggest that the potential confounding effects of height and weight should be considered in such biomechanical evaluations. Considering the range of variability for the height and weight of ten year-old children, it may be appropriate to include these as predictors of skating performance.
The purpose of this study was to evaluate the biomechanical characteristics of minor hockey players while performing an on-ice acceleration skill test. In addition, the study evaluated the contribution of height and weight on the assessment of skating technique. Participants were 30 male development-age hockey players categorized by level of play. Correlation identified the kinematic variables related to time to skate six meters. Regression analysis identified the set of variables that best predicted time to skate six meters. Comparing structural models across studies demonstrates the importance of body size on skating performance. These results illustrate the importance from the development age, through to university athletes, to elite NHL prospects.
The Study of Bond Strength and Bond Durability of Reactive Powder Concrete
Authors: Lee M-G , Chiu C-T , Wang Y-C 
Published: April 2008

This research project aims to use reactive powder concrete, RPC. as a new repair material and evaluate its bond strength and bond durability to existing concrete. One accelerated aging environment, namely a freeze-thaw cycle acceleration deterioration test, was selected for the evaluation of bond durability of the repair materials. Before and after aging, the samples were evaluated by the compressive strength, bond strength (slant shear test), steel pull out strength, and relative dynamic modulus NDT tests.
The test results show that the RPC possesses high bond strength, dynamic modulus, and bond durability as compared with other concretes. The adhesion between the RPC and the steel is also much greater than that for the other concretes. It would be interesting to verify the consequences of this improved adhesion in reinforced concrete structures.
Test results revealed that RPC was still in good condition after 1000 cycles of freezing and thawing in accordance with ASTM C 666-97. After 1000 cycles, the nonshrinkage high strength mortar showed a reduction in compressive strength, slant shear strength, steel pull out strength, and dynamic modulus by 17, 21, 24, and 25 %, compared with the corresponding values of 6, 7, 5, and 10 %, respectively, for RPC. Specimens of normal strength concrete were used as reference specimens. The 5 cm × 10 cm slant shear cylinders made of normal strength concrete had deteriorated severely after 600–700 freeze-thaw cycles. For the normal strength concrete, the average values of relative dynamic modulus of elasticity based on resonant frequencies after 300 and 600 freeze-thaw cycles were 75 and 55 %, compared with the corresponding values of 96 and 92 %, respectively, for RPC.