bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diffusion Theory Calculations for the Pin-Wise Power Distribution in VENUS-I and VENUS-II
Authors: Williams ML , Marshall GM , Chowdhury P , Kam FBK 
Published: December 2008

“Standard” pressurized water reactor (PWR) calculation procedures based on two-group diffusion theory are used to compute the relative pin-power distribution in the VENUS-I and VENUS-II benchmark configurations. These two critical lattices simulate PWR cores which have fresh (UO2) and uranium/plutonium (MO2) pins on the core periphery, respectively.
The purpose of the study is to establish the accuracy of these methods, which are used to obtain the core source distribution for RPV fluence calculations, by comparing the calculated with the experimentally determined relative power variation. Special consideration is given to the core periphery region, which contributes most heavily to the RPV fluence.
It is found that the diffusion calculations agree to within 5 to 10% of the measurements for both the uranium and MO2 cores. It is estimated that this order of source discrepancy will cause only about 5% uncertainty in the computed RPV fluence.
Experience In the Design of Irradiation Rigs for the Harwell D20 Moderated Materials Testing Reactors
Authors: Constantine G 
Published: December 2008

The Harwell MTR’s DIDO and PLUTO have jointly accumulated 60 years'’ operation and much expertise has been amassed in designing irradiation rigs and loops to achieve target fuel ratings, neutron flux levels and spectra. For design purposes our modelling philosophy is based on a variety of calculational routes including Monte Carlo and collision probability methods.
The paper describes the development of the PAT (Pluto AGR Test) Loop currently being commissioned for transient testing of advanced gas-cooled reactor (AGR) fuel pins. The inreactor section of the loop, located in the D2O reflector close to the PLUTO core, includes fixed and variable density absorbers (silver and 3 He respectively) to counteract the flux tilt in the reflector and for inducing rating transients. During both steady operation and the transients the fuel pin rating distributions will be obtained from a combination of collision probability calculation flux solutions normalized to measured instantaneous flux values obtainedfrom online self-powered neutron detectors.
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.
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%.
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.
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.
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.
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.
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.
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 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 &lt; 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.
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.
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.