bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of Radiation-Damage Cross Sections for (Homogeneous) Amorphous Structure Materials
Authors: Matthes W
Published: December 2008

We evaluate the damage function Dia(T) giving the "Global Damage" of type a produced in a cascade initiated by a recoil atom of type i of (recoil) energy T. Global Damage of type a may indicate, for example, the number of vacancies of atoms of type j, ionization produced in the cascade, energy dissipated by electronic heating, and energy dissipated by nuclear heating.

We establish an integral equation of the "importance, or adjoint" type for Dia(T) and solve it numerically. To start directly from an equation for Dia(T) is for our purpose much easier and faster than (1) to construct the flux of moving atoms by solving the Boltzmann equation (e.g., by the Monte Carlo method) and then (2) to evaluate the damage by keeping track of all particle histories and collecting the information at damage events.

The total damage of Type α due to a neutron spectrum ϕ(E) is then given by Dα(ϕ)=∑i∫dE∫dTϕ(E)∑i(T∕E)Diα(T)=∫ϕ(E)=∑α(E)dE where Σ i (T/E) = neutron-reaction cross section for producing recoil atoms of type i with recoil energy T, and Σ α (E) = macroscopic damage cross section (for damage type α) for the material under investigation.

In a first application we evaluate this macroscopic damage cross section (for vacancy production) for 56Fe in the energy range from 7.0 to 40.0 MeV. Fe was taken to be in a homogeneous amorphous phase of density of 7.8 g/cm3.
Neutron Dosimetry Materials Used in European Community Countries
Authors: Fudge AJ , Pauwels J , Audenhove JV
Published: December 2008

The types, form and purity of materials used for neutron metrology in the European Community countries has been reviewed by the Monitor Materials Sub-Group of the European Working Group on Reactor Dosimetry. The requirements of dosimetry techniques used in operational reactors and in associated research and development programs using irradiation rigs are discussed. The specifications for purity and problems associated with the characterization of these materials that have arisen during the dosimetry material production program are reviewed.
Fast Neutron Dosimetry by Means of Fission Foils
Authors: D'hondt P , Fabry A
Published: December 2008

Two techniques are highlighted: (1) Neutron flux determination by distinct fission fragment absolute radiometric measurements on fission foils. The measuring technique and calibration procedure are discussed. Measuring results for the fission fragment escape from the fission foils (pure and alloys) are compared with calculations. Calibration results for 235U(nf) obtained at the French Masurca fast critical facility are presented in terms of fission chain yield measurements. The results are compared with ILRR (Interlaboratory LMFBR Reaction Rate program) and other fission yield complications. (2) Neutron flux determination by detection of the delayed neutrons emitted by a fissile sample. The measuring technique and calibration procedure are discussed. Results are given for 232Th(nf) and 238U(nf). A consistency check between calibration results for both reactions is presented in terms of total absolute delayed neutron yield and fission cross-section data.
Use of Sapphire as a Neutron Damage Monitor for Pressure Vessel Steels
Authors: Pells GP , Fudge AJ , Murphy MJ , Watt S
Published: December 2008

Single crystal α-Al2O3 (sapphire) has been neutron irradiated over a range of dose, dose rate and neutron energy spectra at temperatures from 60 to 310°C. Values of optical absorption at 400 nm, the peak of the aluminum vacancy absorption band, were plotted against damage dose expressed in terms of dpa of Al in sapphire obtained from measurements of induced radio-activity in activation foils irradiated with the sapphires and from calculation of the neutron energy spectrum at the irradiation position. The neutron energy spectrum was calculated using modern neutron transport computer codes and adjusted in the light of measurements obtained from multiple foil activation experiments. A simple response curve was obtained for all sapphires irradiated at temperatures between 220 to 310°C and for sapphires irradiated below 200°C which had been annealed at 29O°C irrespective of dose rate or neutron energy spectrum. The single response curve for irradiations performed in a variety of neutron energy spectra validate the neutron energy spectrum computational procedures and by the same token show that sapphire can be used as a damage monitor in situations where the neutron energy spectra are not well defined.
Neutron Sensitivity of Prompt-Response Self-Powered Neutron Detectors and the Interval Rule
Authors: Molina Avila J , Carmo Lopes M
Published: December 2008

This paper is devoted to the calculation of thermal sth and epithermal sepi sensitivities of cobalt prompt-response Self-Powered Neutron Detectors (SPNDs). The thermal sensitivity was obtained for a Maxwellian neutron field, and the effect of scattering on the self-shielding correction was taken into consideration in the second-collision approximation. The dependence of sth on the emitter radius R was studied in a wide region of R (0.025 to 0.2 cm). The differential and global epithermal sensitivities were calculated using a simple expression for the first-collision neutron absorption probability. Finally, a criterion to evaluate the accuracy of the parameters of the model was established in the form of some Interval Rule which is very sensitive to the radial dependence of the flux perturbation correction and other parameters of the model in both the thermal and epithermal regions.
Electron Spectral Contribution of Prompt-Response Self-Powered Neutron Detectors
Authors: Carmo Lopes M , Molina Avila J
Published: December 2008

In the present work we use a new model for calculating the effective charge induced per neutron capture in a prompt-response Self-Powered Neutron Detector (SPND). This charge is written as the integral over all possible energies of the spectral function S(E) weighted with the electron spectral contribution ∑(E). For the latter function, which has a clear physical meaning. we derived an analytical expression through the path-length distribution function n(k). This relation holds for both finite and infinite length emitters. The method was used to calculate the dependence of the effective charge with the geometry of the detector.
Measurements and Model Predictions for Improved Microcalorimeter Design
Authors: Bainbridge N , Mason JA , Peerless SJ
Published: December 2008

Radiation absorbed dose microcalorimetry is a direct technique for energy deposition measurements in low power benchmark mixed neutron and gamma-ray radiation fields. MkII adiabatic microcalorimeters, developed at Imperial College, are described. The results of recent electrical calibration and 60Co gamma-ray field measurements are presented for graphite and iron microcalorimeters.

In order to assess sources of error, a finite-difference conduction-heat-transfer computer code has been employed to model the microcalorimeter performance. Model predictions are in good agreement with experimental results.

As a result of the error assessment, a redesigned MkV graphite microcalorimeter has been constructed, and results for electrical calibration and 60Co gamma-ray measurements are presented. Systematic errors are reduced by a factor of about 10 for electrical calibration. for the 60Co measurements, the discrepancy between the graphite MkV microcalorimeter and calibrated ionization chambers is less than 2%.
Calibration of a Neutron-Driven Gamma-Ray Source
Authors: Williamson TG , Lamaze GP , Gilliam DM
Published: December 2008

Cadmium and iron cylinders in the thermal-column cavity of the National Bureau of Standards Reactor (NBSR) provide intense sources of neutron capture gamma rays. The strength of the gamma-ray fields have been calculated from measurements of the neutron interaction rates in the cadmium and in the iron cylinders. The neutron interaction rates were measured by activation foils fixed on the surface of the cylinders and by direct counting of the activated cylinders. Miniature fission chambers have been used to measure the axial distributions.
Indoor Air Quality and Ventilation Measurements in Energy-Efficient California State Office Buildings
Authors: Levin H , Phillips TJ
Published: December 2008

During the late 1970s and early 1980s, the State of California designed, built, and occupied a series of innovative, state-of-the-art, energy-conserving office buildings. Occupant complaints of indoor air problems in the first completed structure led to air quality monitoring in that building and two others prior to occupancy. Investigators applied a variety of measurement methods and protocols. Those investigations including air quality and ventilation system measurements are some of the results presented and discussed.

The results of the investigations were used to identify necessary remedial actions and to alleviate potential occupants' indoor air quality concerns. Ventilation system performance measurements were more useful than air quality measurements in identifying necessary remedial actions. Side benefits of these investigations were a “building closeout” procedure (indoor air quality and ventilation system evaluation guidelines) for new state office buildings, as well as an increased awareness of indoor air quality concerns among state personnel responsible for building design, construction and management.
Workshop: Data Collection Aspects of Building Investigations
Authors: Turner WA , Burge HA , Persily AK
Published: December 2008

The purpose of this Workshop was to create a setting for the exchange of information with regard to data collection, which is necessary in order to reach definitive answers when conducting indoor air quality building investigations. The topics covered in this Workshop included overall building HVAC diagnostics, with specific emphasis concerning design versus usage, correct HVAC operation, microbiological evaluations, and tracer gas evaluations of ventilation rates.
Experimental Design and Protocols for Research at GEOMET's Test Houses: A Case Study
Authors: Koontz MD , Nagda NL
Published: December 2008

Two identical, unoccupied research houses were used to investigate relationships among air infiltration, energy use, and indoor air quality in a controlled setting. One of the houses was retrofitted to increase building tightness and was equipped with an air-to-air heat exchanger. Infiltration, energy, indoor air quality, and environmental parameters were monitored before and after the retrofit. It was found that (1) the retrofit decreased air infiltration rates by nearly 25%, (2) heating energy savings of 12 to 20% were achieved through the retrofit, and (3) among pollutants monitored, only radon and radon progeny increased in proportion to the reduced infiltration. Similarly, when the heat exchanger was operated, radon and radon progeny were the only pollutants reduced in proportion to the added air exchange.

The research design, monitoring strategy, and operational protocols documented in writing and followed throughout the project are the subject of this paper.
Design of a Total Human Environmental Exposure Study (THEES) for Benzo(a)pyrene in New Jersey: The Microenvironmental Survey
Authors: Harkov R , Waldman J , Lioy PJ , Greenberg A , Darack F
Published: December 2008

As a result of the combustion of organic substances, benzo(a)pyrene (BaP) is a ubiquitous contaminant of our environment. Ambient air measurements in New Jersey indicate that localized sources are of great importance in influencing outdoor concentrations of this carcinogenic substance. A total human environmental exposure study (THEES) for BaP was initiated by the New Jersey Department of Environmental Protection (DEP). THEES will be carried out in two phases: (a) a microenvironmental survey of air, water, soil, and food BaP levels, and (b) a seasonal THEES. The study area will focus on a community impacted by a grey-iron foundry that utilizes coke in a cupola. Ten homes will be utilized in both the microenvironmental survey and the seasonal THEES, two of which will be in a nonimpact area (control). All homes will include indoor air measurements utilizing low volume PM10 samplers, while three outdoor PM10 high volume samplers will be operated simultaneously with the indoor samplers. Weekly composite food and water samples and individual home soil samples will also be taken. Each family will complete a daily activity questionnaire (AQ) to assist in the interpretation of the monitoring results. Information gathered during the microenvironmental survey will be used to fine-tune the THEES. The initial survey is important in the development of a THEES for trace contaminants, since sampling and analytical protocols may require modification pending the outcome of the microenvironmental investigations. Analysis of the results gathered by THEES will be utilized by DEP to apportion the contribution of various BaP exposure vectors to an individual's total exposure, thus playing a role in the development of cost-effective risk management options for trace contaminants in New Jersey.
Prediction of Long-Term Exposure to Indoor Air Pollutants Using Short-Term Measurements
Authors: White JH
Published: December 2008

The Canadian federal and provincial health ministers released a document in 1987 entitled “Exposure Guidelines for Residential Indoor Air Quality.” These guidelines establish the maximum recommended concentrations of nine pollutants (or pollutant groups) and a range of relative humidities, often with short-term and long-term levels separately identified. No simple measurement can determine whether a residence does and will continue to meet the guidelines. An analysis protocol is needed to predict concentration peaks and averages under conditions that are different from those that occurred during the test. To perform these analyses, many measurements and observations other than the simple point-in-time concentrations must be made. They include: instantaneous air change rates, taken at the same time and point as the pollutant concentrations; envelope leakage and effective ventilation areas; the weather during the test; and a definition of the exposure classification of the residence. This paper develops the logic for, and presents, a proposed protocol and subsidiary measurements and observations that could serve as a first attempt at meeting the needs of such a prediction technique. It is based on the single-cell model of Wadden and Scheff, plus the averaging techniques of Yuill, in addition to a few concepts developed by the author. Research needs include a better definition of non-ventilation removal mechanisms and source variability, as well as verification that the method adequately predicts both long-term average concentrations and critical short-term peaks.
Workshop: Development of Questionnaires and Survey Instruments
Authors: Lebowitz MD , Quackenboss JJ , Soczek ML , Colome SD , Lioy PJ
Published: December 2008

Field studies, surveys, and building investigations are often performed to measure or predict the magnitude of several possible indoor air pollutant exposures and, frequently, to assess potential adverse results of such exposures in populations. This paper focuses on the procedures for indoor air quality data acquisition, processing, and integration for analysis. This includes the basic, practical aspects of implementing field surveys, especially questionnaire development and administration. Recommended procedures are presented, including the use of standardized methods of measurements.
Susceptibility to Inhaled Pollutants
Authors: Utell MJ , Frank R
Published: December 2008

Description

STP 1024 is divided into 5 sections:

• markers and mechanisms of susceptibility

• characterizing the study groups and their responses

• exercise and regional dosimetry

• susceptible populations models

• asthma and controlled clinical exposures to specific pollutants
Standardized Stress-Time Histories—An Overview
Authors: Schütz W
Published: December 2008

After a short historical introduction, the reasons why standardized stress-time histories are necessary and useful are given. A standardized stress-time history must be based on several, preferably many, stress measurements in service. It must also be a fixed stress sequence, not just a spectrum for which an infinite number of stress-time histories are possible. It must be based on a cooperative effort of several competent laboratories, preferably from different countries. It must also be generally applicable to the structure or component in question. The truncation or omission levels, if any, must be clearly stated and must be substantiated by tests. A reasonable return period or block length must be also selected. Preferably, standardized stress-time histories should be used for: 1. comparison of materials, production processes, and design details as well as cooperative (round robin) test programs; 2. investigation of the scatter of fatigue life; and 3. producing preliminary fatigue design data for components etc.; if the service loads on the component in question are of variable amplitude.

Five standardized stress-time histories available at present (Twist, FALSTAFF, Gauss, Helix-Felix, and Cold TURBISTAN) are briefly described as well as the six at present in progress (WASH, WALZ, WISPER, ENSTAFF, Carlos and hot TURBISTAN).
Development of Jet Transport Airframe Fatigue Test Spectra
Authors: Fowler KR , Watanabe RT
Published: December 2008

Aircraft development programs commonly employ large tests to substantiate new design features. Full-scale airframe static and fatigue tests are conducted to demonstrate that the structure has sufficient strength and will be economical to maintain in service. Full-scale fatigue testing is accelerated relative to actual usage so that areas that exhibit early fatigue problems can be located and corrected in a timely manner.

Development of the airframe fatigue test spectra for two new jet transport models is described. These test spectra were based on the concept of applying loads as realistically as possible while conforming to program schedule and test equipment limitations. The frequency and magnitudes of loads were determined to meet observed statistical criteria without relying on damage model assumptions. Test loads were applied in blocks of 5000 flights using five different flight types. Each flight type employed up to 25 flight segments with five load levels for nine major gust and maneuver segments. Test time objectives were met by tailoring the spectra truncation levels. Ancillary panel tests were conducted to evaluate the impact of spectrum variables. The mixture of flights was constructed such that unique fracture face marking would result to simplify subsequent optical microscopy.
Fatigue Crack Growth in a Rotating Disk Evaluated with the TURBISTAN Mission Spectra
Authors: Hull DA , McCammond D , Hoeppner DW
Published: December 2008

Fatigue crack growth rates were generated from four rim cracks in a rotating disk that was evaluated with the TURBISTAN loading spectra. A fractographic investigation revealed the results of correlating variable-amplitude load cycles with fatigue crack striations and that constant-amplitude cycles had been successful in producing marker bands on the fracture surfaces.

An annular disk specimen was designed to study the propagation of through-the-thickness radial-edge fatigue cracks. TURBISTAN, which is a standard loading sequence developed for fighter aircraft disk usage, was employed because it provides a more realistic load sequence than the currently used zero-max-zero cycle. The MINITURB version for cold compressor disks was used in this study.

An approximate stress intensity solution for a radial-edge crack in a rotating annular disk was developed from two existing solutions by superposition. An aluminum 6061-T6 alloy was selected to provide a readable fracture surface because it striates well. The disk was precracked on a load frame to introduce known discontinuities. It was then evaluated in a spin pit with MINITURB and constant-amplitude cycles. The constant-amplitude cycles were used to create marker bands on the fracture surface to aid a subsequent fractographic investigation. Periodic fluorescent penetrant inspection allowed fatigue crack growth to be tracked.

A scanning electron microscope was used to study crack fracture surfaces, correlate MINITURB cycles with fatigue striations, and identify marker bands. Plots of discontinuity length versus cycles and crack growth versus stress intensity are presented. The importance of coupling a realistic mission cycle with the spin pit evaluation of engine disk materials was emphasized.
Fatigue Spectra Development for Airborne Stores
Authors: Gallagher VM , York RL , Fuchs HO
Published: December 2008

Traditionally, airborne store design has been based on service life criteria similar to those used for aircraft development. Recent research has shown that an airborne store may be exposed to a unique loading environment and may therefore require a different approach. Moreover, flight loads data for aircraft and airborne stores are normally difficult and expensive to obtain, because resources are not available to fly a sufficient variety of combinations of aircraft, stores, and mission types. Finally, the increased life of many stores has made fatigue life an important consideration in design. These considerations led to development of an approach to building flight-load spectra for fatigue testing of externally mounted airborne stores (that is, fuel tanks, missiles, bombs, etc.) using time-history load data collected from U.S. Air Force and Navy training flights. The data are processed using a “racetrack” type data compaction algorithm to yield sequential peak/valley pair files, and then reorganized to build new mission profiles. Finally, the new mission profiles are weighted by expected frequency of occurrence and organized to reflect the expected service use over a period of time.
Simplified Analysis of Helicopter Fatigue Loading Spectra
Authors: Dowling NE , Khosrovaneh AK
Published: December 2008

In employing the Palmgren-Miner rule for irregular loading spectra applied to notched mbers, it is necessary to employ rain-flow or an equivalent cycle counting method, and also to consider the accelerated damage at low stress levels due to the presence of high-level cycles. Additional interactions between high and low stress levels, which are associated with local notch mean stress effects, also occur and can be specifically analyzed using the local strain approach. A simplified application of the local strain approach is described that results in upper and lower bounds on life being calculated. This is applied with reasonable success to the standard helicopter loading spectra Helix and Felix, and a much simplified version of Helix is proposed that consists of repetitions of a single typical flight.
Mechanical Properties of Küntscher Nail Sections
Authors: Daniels AU , Bayne NR , Hofmann AA
Published: December 2008

The purpose of this study was fourfold: determine the section rigidity in torsion and bending of three commonly used sizes of Küntscher-type nails obtained from a single source; compare the results with calculated values based on section geometry and material properties; determine the effect of a transverse hole (intended to accommodate a locking device) on section properties; and determine the effect of simulated-use cyclic loading on properties of sections with transverse holes. Because rods of this design are slotted and asymmetrical in cross section, bending tests were performed in two orientations, 0 deg (slot-down) and 90 deg (slot rotated 90 deg from the slot-down position).

We found that the change from an 11-mm to a 15-mm rod diameter increased rod stiffness and strength by about a factor of two, except in the 90-deg orientation, where closure of the rod open section under load markedly reduced strength and stiffness for all rod sizes. Neither the transverse holes nor cyclic load exposure had a marked effect on section properties. In torsion, measured stiffness essentially equaled calculated stiffness. There was not a similar equality in measured and calculated stiffness in bending because the point loading in the actual tests produce much different effects on open sections than the pure bending moments used in the calculations.

We also concluded that ASTM F 383 needs to be modified to incorporate a more conventional use of terminology for structural stiffness or rigidity and strength, and a method for measuring deflections that recognizes the problem of open sections. It also seems appropriate to modify the gripping method for torsion tests to include the use of mechanical chucks.
Testing Method for Evaluating Bending Stiffness and Torsional Stability of Femurs Implanted with Intramedullary Nails
Authors: Butts MK , Bechtold JE , Hoeltzel DA , Kyle RF , Gustilo RB
Published: December 2008

A testing method to evaluate the performance of intramedullary (IM) nails in stabilizing femur fractures and to compare the effects of different design features is presented in this study. Techniques are described for preparing specimens, creating fractures, potting bones for testing with electrohydraulic materials testing machine, testing in bending and torsion, and measuring flexural stiffness and torsional stability. Flexural stiffness is calculated from the moment versus deflection curve. The femur is rotated to 10 deg from neutral, and the torque generated at this forced rotation is recorded. The torque is then released by rotating the femur back to the neutral position, and the angle at which the torque returns to zero is recorded as the springback angle. The springback angle indicates the amount of slippage between the intramedullary nail and bone, or their relative stability in torsion.
Mechanics of Distal Locking in Intramedullary Rods: Comparison in Osteoporotic and Normal Femurs
Authors: Latta L , Zych GA , Greenbarg P , Milne T
Published: December 2008

The pseudostatic torsional stiffness and strength of fixation of two types of distal locking intramedullary nails was measured in embalmed human femora which were graded for osteoporosis. Cortical distal locking (Grosse-Kempf) was stronger than cancellous distal locking (Brooker-Wills) rods in both normal and osteoporotic femora. There was also a significant loss in strength of fixation for osteoporotic versus normal bones with either type of fixation, but the difference was more pronounced with cancellous fixation.

Cyclic testing to ±20 deg internal and external rotation showed no difference in loosening between cortical and cancellous locking in normal bones. But in osteoporotic bone, loosening was proportional to degree of osteoporosis with cancellous locking and was significantly greater than with cortical locking. There was no significant difference in loosening for cortical locking rods in normal versus osteoporotic bone.
A Method to Evaluate Motion at the Bone Fracture Interface on Intramedullary Nailing
Authors: Lynch GE , Davidson JA
Published: December 2008

Two methods were used to evaluate motion at the fracture site in cadaver femurs stabilized with intramedullary (IM) nails. Both bending stability at the fracture site and torsional stability of slotted and unslotted IM nails were evaluated. The first method was to manually measure the rotational stability of the device itself. The second method characterized the fracture displacement in a femur under anatomical load. Both slotted and nonslotted stainless-steel IM nails were fixed statically (proximal and distal screw fixation) in identical cadaver femurs. The distal end of each femur was fixed in epoxy and a circumferential saw cut carefully made at the mid-shaft location. The load was physiologically applied at a 12-deg angle anteriorly in the anterior-posterior plane. Displacements at the fracture site were recorded as a function of the applied load.

Results showed the bending displacement for both types of IM nails to be essentially zero. This was expected because both ends of the nails were fixed and because the opposing fracture surfaces on the medial side of the femur loaded against each other. However, the rotational displacement for the slotted nail was significantly greater than that of the unslotted nail. This was consistent with bench tests, which showed a similar trend in the rotational stiffness.
Initial Mechanical Stability of Three Distally Locked Intramedullary Nail Systems
Authors: Daniels AU , Hofmann AA , West HS , Morgan JM
Published: December 2008

Both the initial torsional stability and axial compressive fixation strength were compared using human cadaver femoral specimens, for three intramedullary nail systems incorporating distal transverse locking: the Grosse-Kempf (GK), Brooker-Wills (BW), and an experimental system referred to informally as the Utah Nail (UN). Unlike the GK system, the BW and UN devices utilize internally deployed distal fixation components to provide transverse stabilization without the need for either mechanical aiming devices or distal incisions for placement of components. The experimental UN system provided greater stabilization and strength than the BW but less than the GK, especially with respect to strength. The UN system has been used successfully in a small number of clinical cases, and it is not yet clear what levels of stabilization and strength are needed in various clinical situations.
The Role of Medullary Reaming in Closed Nailing of Femur Fractures
Authors: Amis JA , Frank DJ , Burkhead WZ , Bucholz RW
Published: December 2008

This study compares results of unreamed Schneider intramedullary nailings with reamed Küntscher intramedullary nailings. Eighty consecutive closed intramedullary roddings of femoral shaft fractures performed at Parkland Memorial Hospital, Dallas, were reviewed. In the first 40 cases, straight, narrow Schneider or Küntscher rods with an average diameter of 10 mm were inserted following closed reduction. No reaming maneuvers and no effort to attain rigid cortical contact with either fracture fragment were made. In the next 40 cases, the standard Küntscher technique with reaming and cortical impingement of the nail on both fragments was employed using Küntscher nails of an average diameter of 13 mm. All patients were followed to fracture union. Analysis of patient and fracture variables (such as anatomic location and degree of comminution) showed no significant differences in the two groups. While both groups demonstrated multiple minor complications, including slight shortening, mild angulation, and variable degrees of malrotation, major complications were significantly greater in the nonrigid rod group. They included one nonunion, three implant failures, and several cases with unacceptable shortening.

Medullary reaming allows the use of stronger rods, improves stable osteosynthesis by permitting cortical contact with the nail, minimizes postoperative shortening, and stimulates healing by depositing morselized bone reamings in the fracture of hematoma. The versatility of the closed technique is markedly enhanced by routine reaming.
Intramedullary Fixation of Unstable Trochanteric Fractures of the Hip
Authors: Henry SL , Koenig T , Rosenberg S , Seligson D
Published: December 2008

The Küntscher Y-nail is a two-piece intramedullary device used in the management of unstable trochanteric fractures. The Y-nail consists of a Küntscher intramedullary nail and a fenestrated femoral neck component. This device offers distinct biomechanical and clinical advantages when compared with the compression hip screw, blade-plate device, or other intramedullary fixation.

This retrospective study evaluated 137 patients with unstable fractures of the hip. Results were evaluated by specific criteria: pain, extremity shortening, range of motion, deformity, and ambulatory status. Management with the Y-nail resulted in 36% excellent, 44% good, 16% fair, and a 4% poor result. Clinical experience with this technique resulted in a short operative time, limited blood loss, decreased soft tissue trauma, and early patient ambulation.

The Küntscher Y-nail may provide a favorable alternative to other methods used for stabilization of fractures of the proximal femur.
Evaluation of WWER-440 Surveillance at Paks NPS
Authors: Gillemot F , Trampus P , Rittinger J
Published: December 2008

The surveillance program of the WWER-440 type pressurized water reactors (PWRs) is somewhat different from the surveillance programs of other PWRs. In view of this, a surveillance evaluation system was developed to solve the open questions connected with the design. This system was used to evaluate the results of the first two units of Paks NPS. This system compares the results of mechanical testing of surveillance specimens, dosimetry, nondestructive inspection, and stress and strain calculations under transient load. The final results show that the pressure vessel of the first unit is safe for the planned full 30 years lifetime without any change in the core or in the mode of operation. It is hoped that similar conclusions will be drawn after having completed surveillance measurements on the three other similar units under operation or construction.
Neutron Embrittlement Surveillance Program at Krṡko Nuclear Power Plant
Authors: Najzer M , Glumac B , Kodeli I
Published: December 2008

Presented are results of the testing of the first surveillance capsule of the Kṡsko Nuclear Power Plant. The plant is a 632-MWe two-loop pressurized water reactor (PWR). The pressure vessel is made of low-copper steel. The projected lifetime neutron exposure of the pressure vessel is 6 ∙ 1019 n/cm-2E > 1 MeV. The first surveillance capsule was irradiated to 1.75 effective full power year (EFPY). The neutron exposure of irradiated specimens was between 7.4 to 9.4 ∙ 1018 n/cm2 E > 1 MeV depending on specimen positions. Observed ▵RTNDT are higher than given by predictive formulas for all except base material in transverse direction. The ratio observed versus predicted for weld was found to be 2 and 5 in the case of Regulatory Guide 1.99, Revision 1 and Revision 2, respectively. Observed change in the upper shelf energy is of the order of a few percent and is hidden by the spread in measured values.
Residual Life Assessment of Light Water Reactor Pressure Vessels
Authors: Shah VN , Server WL , Odette GR , Amar AS
Published: December 2008

The service-dependent degradation (aging) of light water reactor (LWR) pressure vessels due to irradiation embrittlement is discussed in this paper. The major variables which influence the irradiation embrittlement of LWR vessels are the copper and nickel content of the vessel materials and the fluence. The vessel beltline region is subjected to the largest fluences. A surveillance program, which consists of tension and Charpy-V-notch (CVN) testing of irradiated specimens of base, heat-affected-zone, and weld materials, is required to monitor changes in their embrittlement. Three main unresolved technical issues are: (1) the limited range and accuracy of the current correlations for calculating shifts in the reference temperature for nil-ductility transition (RTNDT) and changes in the Charpy upper shelf energy; (2) the need to demonstrate the conservatism of using CVN-based RTNDTshifts for certain sensitive reactor pressure vessel materials; and (3) the type of surveillance program required for any renewed operating license period. The damage caused by irradiation embrittlement can impact plant operating procedures, including heat up/cool down and hydrostatic test procedures, as well as the acceptability of various plant transients.
Evaluation of Thermal Annealing Behavior of Neutron-Irradiated Reactor Pressure Vessel Steels Using Nondestructive Test Methods
Authors: Popp K , Brauer G , Leonhardt W-D , Viehrig H-W
Published: December 2008

Usually the assessment of the irradiation sensitivity and annealing behavior of reactor pressure vessel (RPV) steels is performed by means of destructive test methods, mainly impact and tension tests. In this paper a new kind of search for an efficient temperature-time regime for postirradiation thermal heat treatment is presented using nondestructive test methods like positron annihilation (Doppler broadening pararneter S) and hardness (Vickers hardness HV 10).

Samples of Cr-Mo-V RPV steels (Soviet type 15Kh2MFA) were irradiated to different fluence levels of fast neutrons at temperatures T < 156°C in a test reactor (base metal) and T = 265°C in a pressurized water reactor (base as well as weld metal). From isochronal and isothermal annealing curves of HV 10 and S, favorable temperature-time regimes for each type of irradiated material were estimated. The data obtained from tension and impact tests indicate that sufficiently large recoveries took place by application of these regimes.

The new approach presented is especially useful in such cases where only the smallest amounts of irradiated materials are available—a case often met for RPV surveillance specimens.
Semiempirical Model for Annealing and Reirradiation Embrittlement in Pressure Vessel Steels
Authors: Mager TR , Lott RG
Published: December 2008

A model of recovery and reembrittlement in an annealed nuclear reactor pressure vessel steel is described. Modeling is an integral part of the overall approach to annealing because it provides a bridge between the experimental studies and the application of the results to actual pressure vessels. This model is based on a series of annealing and reirradiation studies performed using microhardness specimens. Most of these materials were originally irradiated in nuclear pressure vessel surveillance programs. The model is based on the concept of a benefit factor, which compares the annealed and unirradiated specimens to material that has been irradiated without an intermediate anneal. It is noted that the data can most reasonably be explained by assuming that the mechanism of annealing is a combination of reversible and nonreversible processes. This model can be used to predict transition temperature shifts in annealed materials.
Status of Research to Assess Radiation Effects on Crack-Arrest Toughness of RPV Steels
Authors: Marschall CW , Rosenfield AR
Published: December 2008

This paper provides an overview of work completed and in progress worldwide to study the effect of radiation on the static crack-arrest toughness, KIa, of reactor pressure vessel steels. The impetus for obtaining such data is the desire to realistically assess the need to repair or retire vessels that have been exposed to radiation in service, and to avoid the sometimes unnecessary conservatism associated with safety analyses when no KKIa data are available.

The paper reviews recent developments toward achieving an ASTM standard test method for measuring KIa. It demonstrates also the acceptability of using crack-arrest specimens that are appreciably smaller than those used frequently in the past, thereby increasing the practicability of studying radiation effects on KIa.

The review points out that the data currently available for assessing radiation effects on KIa are very limited: only 36 of the more than 900 test results in the Battelle/United States Nuclear Regulatory Commission (USNRC) Crack Arrest Data Bank are for irradiated specimens. Nonetheless, those limited data suggest procedures for estimating radiation effects on KIa that are more realistic (less conservative) than those currently specified in Section XI of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code. Additional tests that include several fluence levels and wider ranges of composition are required, however, to verify the modified procedures or to reveal alternate approaches.
Dynamic Delamination Buckling in Composite Laminates Under Impact Loading: Computational Simulation
Authors: Grady JE , Chamis CC , Aiello RA
Published: December 2008

A unique dynamic delamination buckling and delamination propagation analysis capability has been developed and incorporated into a finite-element computer program. This capability consists of (1) a modification of the direct time integration solution sequence which provides a new analysis algorithm that can be used to predict delamination buckling in a laminate subjected to dynamic loading and (2) a new method of modeling the composite laminate using plate bending elements and multipoint constraints. This computer program is used to predict both impact-induced buckling in composite laminates with initial delaminations and the strain energy release rate due to extension of the delamination. It is shown that delaminations near the outer surface of a laminate are susceptible to local buckling and buckling-induced delamination propagation when the laminate is subjected to transverse impact loading. The capability now exists to predict the time at which the onset of dynamic delamination buckling occurs, the dynamic buckling mode shape, and the dynamic delamination strain energy release rate.
Edge Stresses in Woven Laminates at Low Temperatures
Authors: Kriz RD
Published: December 2008

Woven glass-epoxy laminates are used as nonmetallic components at low temperatures in magnetic fusion energy structures. Previous damage studies on G-10CR and G-11CR cryogenic grade woven laminates revealed that most of the damage occurred in the laminated interior. An existing, generalized plane strain, finite element model was modified to predict stress states at the laminate interior and free edges. Finite element results demonstrated that the weave geometry reduces edge stresses at low temperatures. Delamination edge stresses in woven laminates are more sensitive to small changes in temperature than those in nonwoven laminates.
Mode I Interlaminar Fracture Toughness of Unidirectional Carbon Fiber Composites Using a Novel Wedge-Driven Delamination Design
Authors: Glessner AL , Takemori MT , Vallance MA , Gifford SK
Published: December 2008

The mode I interlaminar fracture behavior of unidirectional carbon fiber composites with PMR-15 polyimide and PEEK (polyetheretherketone) matrix resins has been studied at various temperatures and testing rates. These materials were evaluated for strain energy release rate, GI, using a novel wedge-driven delamination (WDD) design. In this WDD configuration, GI is directly proportional to the measured load necessary to advance the sample onto the wedge. The crack front remains essentially stationary in the laboratory reference frame during steady crack growth, facilitating the monitoring of the fracture process. Furthermore, the crack velocity can be set to any desired value by controlling the machine crosshead speed. Steady crack growth was observed in the polyimide laminates, which exhibited an average fracture toughness of 370 J/m2 at 25°C. The measured GI values were slightly dependent on test rate and showed an increase in toughness at increasing temperatures in the range of 25 to 200°C. The toughening mechanism of bundle pullout seemed to be more dominant at higher temperatures, possibly accounting for the higher toughness values. The PEEK laminates exhibited the stick/slip crack growth behavior typical of ductile matrix composites. Slow growth regions were identified by whitened areas on the fracture surface, while the fast fracture areas remained unwhitened. The strain energy release rates of the composite corresponding to both the onset of fast fracture and the arrest of the crack were measured as a function of temperature and rate. While the arrest GI values were fairly independent of temperature and rate, the GI values for instability onset increased with increasing temperature.
Residual and Unspecified Elements in Steel
Authors: Melilli AS , Nisbett EG
Published: December 2008

Description

Peer reviewed papers address the state of the art on residual and unspecified elements in steel from manufacture to end use. Includes practical examples from industry of beneficial as well as detrimental effects of properties associated with residuals.
Lateral Impact of Composite Cylinders
Authors: Christoforou AP , Swanson SR , Beckwith SW
Published: December 2008

An analytical study was conducted to explore and understand the mechanics of the lateral low-velocity impact of composite cylinders by a heavy mass. Two simple models are presented, which when compared with the experimental data demonstrate that the fundamental features of the impact event are represented. Although the results are preliminary, a failure model based on linear laminated shell theory and linear fracture mechanics gave a reasonable representation of the observed impact damage. A nonlinear ring model gave good insight into the physics of the impact event in the presence of delaminations and the resulting nonlinear effects.
Accelerated Rebar corrosion When Connected to Lightning Conductors and Protection of Rebars with Needles Diodes Using Atmospheric Electricity
Authors: Skoulikidis T , Tsakopoulos A , Moropoulos T
Published: December 2008

The regulations for construction in many countries impose the connection of lightning conductors to concrete rebars. In the present work the effect of this connection on the corrosion of rebars was studied in order to avoid connections that accelerate corrosion. With this objective, steel specimens, steel pipes, and normalized reinforced concrete specimens in the air, water, saline water, and buried in the soil connected to lightning conductors or needles were used, and measurements of potential time, potentiostatic curves, and weight loss were taken. In some cases artificial lightning and radioactive lightning conductors were used. It was found that these connections influence the corrosion rate. It depends on the electrical characteristics of the atmosphere (conductivity and type of charge of the atmosphere and earth), that is, on the season and the weather. In most cases (winter, mostly during December in Greece) the corrosion is accelerated. In some cases (spring, mostly during May in Greece) the electron flow is inversed, and protection is found. The overall phenomenon for the whole year is an acceleration of the corrosion from 35 to 70%. The artificial lightning and the use of radioactive lightning conductions also accelerate the corrosion. It follows that the grounding of lightning conductors must be separately made with a network to divide the charge of lightning and should not be connected to the rebars.
Thermal Efficiency of Counterflow Insulation Systems: Possible Applications
Authors: Langlais C , Arquis E
Published: December 2008

In the last few years, papers have been presented on so-called dynamic or counter-flow insulation systems. These studies show significant reductions of thermal heat losses for such systems in comparison with “classic” insulation systems. Residential and industrial buildings using this technique already exist in Scandinavian countries and France. The aim of this study has been to obtain a better understanding of the actual efficiency of such systems.

After a brief reminder of the principle of this insulating technique, the authors present (1) a theoretical model by means of which values of thermal efficiency are derived, and (2) the experimental findings obtained under full-scale laboratory conditions. We then consider the limits and potential applications of dynamic systems.