bluuebunny/crossref_metadata_2025 huggingface dataset:
Observation of Pulsed Neutron Fields with Solid-State Track Recorders
Authors: Roberts JH , Gold R , Preston CC , McElroy WN , Morgan JF , Clark D , Ramos RA , Redhead DL
Published: December 2008

A device called “Der Spinner” has been developed and tested. Its purpose is to obtain time-dependent information on neutron fluence/spectra by using solid-state track recorders. It should prove particularly useful in fast neutron bursts such as occur in nuclear fusion reactors. In the present version of the device, a rotating drum with four strips of track recorder material, such as mica, are placed around the cylinder in the direction of rotation.The cylinder has a diameter of 7.62 cm (3.0 in.). It is rotated by a synchronous motor at an angular speed of 3600 rpm. Each mica strip rotates under a collimating slit system. An actinide deposit or foil is placed in contact with the slit. Fission fragments are collimated through slits of 0.2 and 0.5 mm in the tests made, giving efficiencies of 0.0298 and 0.0745, respectively. Static tests were made with a 252Cf source; dynamic tests were made at an accelerator used in the pulsed mode at the Lawrence Livermore National Laboratory. Time resolutions on the order of 25 μS were obtained for the 0.2 mm slit, and about 50 μS for the 0.5 mm slit.Tests are continuing to determine the precision with which absolute fission rates can be obtained. Rotation speeds and drum diameters can be varied to obtain time resolutions suitable for a variety of experiments.
Status Report on NRC/MEA Dose Rate Experiments in the Buffalo Reactor
Authors: Hawthorne JR
Published: December 2008

This report describes a set of experiments undertaken using a 2 MW test reactor, the UBR, to qualify the significance of fluence rate to the embrittlement produced in reactor pressure vessel steels at their service temperature. Test materials include two reference plates (A 302-B, A 533-B steel) and two submerged arc weld deposits (Linde 80, Linde 0091 welding fluxes). Specimen types are Charpy-V (Cc), tension, and 0.5T compact tension specimens. Target fluence rates are 8 × 1010, 6 × 1011 and 9 × 1012 n/cm2 s-1. Initial findings are reported. The data describe a fluence rate effect which may extend to power reactor surveillance as well as test reactor facilities now in use. A different embrittlement sensitivity versus fluence rate relationship was observed for the A 302-B plate compared with the Linde 80 weld deposit.
European Workshop on Radiation Damage Correlations and Dosimetry
Authors: Alberman A , Dierckx R
Published: December 2008

Material property changes after irradiation are generally investigated in dedicated facilities such as test reactors and particle beams. Correlations with exposure parameters and subsequent engineering applications require damage models and spectrum and damaging fluence determination, achieved by dosimetry techniques, involving reaction rate measurements. The relevance of these exposure parameters with respect to experimental results was the topic of the workshop under discussion.
Determination of Gamma-Ray-Induced Displacement Rates
Authors: Gold R , Roberts JH , Doran DG
Published: December 2008

To define the gamma-ray component of the radiation field in light water reactor (LWR) pressure vessel (PV) environments, gamma-ray spectrometry experiments were conducted in the low power PV mockup at the poolside critical assembly (PCA) at the Oak Ridge National Laboratory (ORNL). Gamma-ray displacement rates can be calculated directly from absolute electron spectra observed with the Janus probe gamma-ray spectrometry. Gamma-ray displacement results are presented for the 1/4-T, 1/2-T, and 3/4-T locations of the 12/13 and 4/12 simulated surveillance capsule (SSC) configurations. In addition, the gamma-ray displacement rate at the SSC location was inferred using thermoluminescent dosimeter (TLD) gamma-ray dosimetry results obtained in the 4/12 SSC configuration at the PCA. Compared with neutron-induced displacement rates, the calculated gamma-ray-induced displacement rates are small at all these LWR-PV locations. The ratio of gamma-ray-induced to neutron-induced displacement rates never exceeds roughly 5 × 10 -3.
Application of Boron Covers for Neutron Spectrum Determination Purposes in Various Neutron Environments
Authors: Végh J , Zijp WL , Nolthenius HJ , Alloggio G , Brega E
Published: December 2008

Foil irradiation experiments were carried out at LFR (ECN. Petten) and WWR-SM (KFKI, Budapest). The effect of boron covers on the activation and fission detector response regions has been investigated. Fluence rate perturbation due to the applied B4C box in graphite or water was determined by means of transport calculations. Neutron spectrum adjustments were performed by the SAND-II and STAY'SL codes. The B4C cover shifts the response regions of the resonance reactions from the thermal region to the 0.1 keV to 1.0 MeV interval. Where boron-covered reactions are used in a least squares spectrum adjustment procedure, the uncertainty of the spectrum is reduced significantly in the intermediate energy region.
Analysis of Solid-State Track Recorders with the Westinghouse Research and Development Center Automated Track Counter
Authors: Ruddy FH , Manhardt AE , Seidel JG
Published: December 2008

A new automated image analysis system for counting neutron-induced fission fragment tracks in mica solid-state track recorders (SSTRs) has been developed and is in use at the Westinghouse Research and Development Center. This computer-controlled optical microscope uses state-of-the-art image enhancement and pattern recognition techniques to identify tracks. Track pile-up corrections have been eliminated for track densities up to 8 × 105 tracks/cm2.

The system has been absolutely calibrated to better than 2% uncertainty in the track density range from 1 × 104 tracks/cm2 to 8 × 105 tracks/cm2. The track counting efficiency is independent of local track density variations over this range.

Key scanning parameters are stored on a microscope field of view by field of view basis and form a part of the long-term Quality Assurance records for SSTR analysis.
Spectrum Measurements on Filtered Neutron Beams for Medical Applications
Authors: Constantine G , Brenen A , Moore PGF , Perks CA
Published: December 2008

Boron neutron capture therapy involves thermal neutron irradiation following preferential incorporation of boron by 10B-loaded tumor-seeking drugs. Attenuation precludes deep-seated tumor treatment using incident thermal neutrons. Attention is now being focused on epithermal/intermediate neutrons subsequently moderated in tissue to give a more uniform flux distribution, suitable for brain tumor therapy.

Choice of incident neutron energy is critical because the proton recoil damage is indiscriminate. Following irradiations of various biological cell lines in vitro with and without boron perfusion in our iron-filtered 24.5 keV beam, we have developed an argon/aluminum/sulfur/filtered broad spectrum beam. The paper describes our proton recoil spectrometry for the > 10 keV range and determination of the spectrum below that using spectrum modifiers such as 10B, V, and Ti. The adjustment code SENSAK was used to obtain our best estimate of the beam spectrum, from which a mean energy of 9.8 keV was derived.
Personnel Neutron Dosimetry Area Monitoring Using Solid-State Track Recorders
Authors: Ruddy FH
Published: December 2008

Personnel neutron dosimeters using a number of different techniques have been developed for routine use in neutron fields, but all of these dosimeters must be carefully corrected to account for the fact that their response is critically dependent upon the energy distribution of the neutron field. At present, personnel neutron dosimeters are typically calibrated in a standard neutron field (e.g., 252Cf or D2O-moderated 252Cf)- but may then be applied in neutron fields that vary considerably from the calibration field. Some widely used personnel dosimeters, such as TLD-albedo dosimeters, overrespond to low energy neutrons and therefore deliver high readings in fields that are more moderated than the standard field.

The solution to the problems created by this energy dependence of the calibration of personnel neutron dosimeters is to obtain accurate experimental information on the neutron energy spectra in the fields to which the personnel dosimeters will be exposed. This paper discusses an effective and accurate means to obtain this information by the application of solid-state track recorder neutron area monitors.
Investigation of a Washington, D.C. Office Building
Authors: Persily AK , Turner WA , Burge HA , Grot RA
Published: December 2008

This paper describes the techniques used to study a Washington, D.C. office building with a long history of indoor air quality and thermal comfort complaints. More than twenty investigations, mostly relatively short term, have been conducted since 1978 to determine the causes of the building's problems and to recommend corrective actions. More recently a long term, intensive study of the building has been undertaken to study the building more thoroughly and to investigate the application of several techniques for studying office building air quality. These techniques include tracer gas measurements of air exchange rates, ventilation system performance and ventilation effectiveness, and measurements of the levels of various indoor pollutants including bioaerosols. This paper reviews the previous investigations of the building and describes the procedures used in the current study. Some preliminary results of the current effort are presented.
Project and Problem Definition in Building Air Quality Investigations
Authors: Allard PF
Published: December 2008

Building air quality investigations can involve a variety of organizational interests and technical interactions that are not always recognized by those requesting an investigation. In order to be effective, field investigators must determine if the parties who are responsible for and affected by a problem building understand the complexity and subtlety of the potential causes, and, if they do not, be prepared to provide education and a frame of reference to help them to approach a common level of understanding. A general approach is needed for the preparation of the managers and occupants of commercial buildings for involvement in an indoor air quality investigation.

A common difficulty is an initial lack of appreciation of the range of interests, causes, interactions, and responsibilities which can be involved in the investigation and solution of an indoor air quality problem. These issues are discussed and outlines are presented for use in project and problem definition.
Indoor Air Quality Diagnostics: Qualitative and Quantitative Procedures to Improve Environmental Conditions
Authors: Woods JE , Morey PR , Rask DR
Published: December 2008

Procedures conventionally used in industrial hygiene are often inappropriate for application in non-industrial environments. More sensitive procedures are needed, since comfort, occupant well-being, and general population susceptibilities are parameters not now addressed by occupational threshold limit values (TLVs). A common result is that compliance with industrial hygiene standards may be demonstrated, but complaints from occupants persist. A new discipline, building diagnostics, is useful in addressing these more sensitive parameters. An application of this discipline to the evaluation of indoor air quality is presented in this paper.

A fundamental aspect to building diagnostics is the need to understand the relationships that exist between the building, its systems, and its occupants. This understanding is developed initially through qualitative diagnostics in which the scope of investigation is defined, appropriate environmental performance criteria are determined, the nature of any existing complaints is reviewed, and an engineering assessment of the HVAC system is conducted. From these qualitative data, a set of hypotheses is developed in terms of the inadequacies of the performance or the opportunities for improvement. Based on these hypotheses, system performance under various loads is predicted and ways to mitigate and improve performance are recommended. An important advantage of this approach is that many problems can be solved at this stage before measured data are required.

However, in some cases, objective and subjective measurements may be required to confirm hypotheses and to substantiate or modify the previous recommendations. In these cases, quantitative diagnostics is indicated. Because of the cost involved in this phase, measurement locations must be identified carefully. We find that five locations in a functional area of the building are sufficient to characterize system performance and occupant response: locations of least ventilation effectiveness, strongest contaminant source, most susceptible occupants, a “control location,” and an outdoor location. Only those quantitative measurements appropriate to the hypotheses are taken; these may include air quality, thermal, lighting, and acoustics parameters. Simultaneously, questionnaires are also used to measure human responses to the environmental conditions within the occupied spaces. These quantitative data are analyzed for compliance with the performance criteria. Recommendations for modifications are then made which address employee concerns, architectural concerns, and cost-effective operation.
Case Study: Multipollutant Indoor Air Quality Study of 300 Homes in Kingston/Harriman, Tennessee
Authors: Hawthorne AR , Dudney CS , Tyndall RL , Vo-Dinh T , Cohen MA , Spengler JD , Harper JP
Published: December 2008

An indoor air quality study of 300 homes in the Kingston/Harriman area of East Tennessee was conducted during 1985–86. This location is one of six locations selected in a larger Harvard University study to evaluate air quality and respiratory health. Homes in each study city were selected based on the participation of a school child in the concurrent Harvard Acute Respiratory Health Study. Eight groups of houses were chosen based on the presence or absence of the following sources: cigarette smoking, wood stoves, and kerosene heaters. A group of “core” measurements is being conducted in all six of the Harvard study cities for nitrogen dioxide, respirable particulate matter, water vapor, and air exchange rates. A detailed questionnaire of home characteristics and occupant behavior is also administered. Supplemental indoor air quality measurements were conducted in the Kingston/Harriman study for radon, formaldehyde, polynuclear aromatic hydrocarbons, and airborne micro-organisms. Measurements were made for a two-week period (except for radon and micro-organisms) in each house during the winter season and again during the summer season. Both vapor phase and paniculate phase polynuclear aromatic hydrocarbons were monitored. Viable airborne bacteria and fungi were sampled in a large subset of houses. Detailed energy use/weatherization surveys were conducted by utility trained auditors. Study protocols and preliminary monitoring results are presented.
Selected Protocols for Conducting Field Surveys of Residential Indoor Air Pollution Due to Combustion-Related Sources
Authors: Traynor GW
Published: December 2008

As buildings are tightened for energy conservation purposes, the concentration of indoor-generated air pollutants can increase. Federal agencies, state agencies, utilities, and public health organizations have an interest in indoor air-pollution levels and the impact various policy decisions will have on them. This paper identifies key parameters that affect indoor air pollutant levels from combustion related sources and suggests protocols for measuring each parameter. Indoor air quality field studies should measure the indoor pollutant levels themselves and the key parameters that affect such levels. Key parameters such as appliance usage patterns, indoor pollutant reactivity rates, local ventilation effects, air exchange rates, and source usage driving forces are addressed. In addition, state-of-the-art measurement techniques, time sampling periods, and overall sample sizes needed are briefly discussed.
Real-Time On-Line Chromatographie Determination of Volatile Organic Emissions
Authors: Bayer CW , Black MS
Published: December 2008

Volatile organic compound (VOC) emissions from consumer products were determined using an environmental chamber coupled with a capillary gas Chromatographie system. The Chromatographie system encompasses a gaseous sample introduction system and a cryogenically cooled Chromatographie column. Direct determination of VOC emissions originating from consumer products within an environmental chamber is feasible.
Application of a Multisorbent Sampling Technique for Investigations of Volatile Organic Compounds in Buildings
Authors: Hodgson AT , Girman JR
Published: December 2008

An analytical method for volatile organic compounds (VOC) which employs a multisorbent sampler containing, in series, Tenax-TA, Ambersorb XE-340, and activated charcoal is described. The method was evaluated in the laboratory and was used to measure concentrations of VOC at a school and an office building. The sampler quantitatively collects compounds spanning a broad range of boiling points, including highly volatile solvents. The overall precision of the method is better than 10% and often better than 5%. The composition and concentrations of VOC in the two, approximately five-month old, nonresidential buildings were similar and also similar to the composition and concentrations in typical residential indoor air. Concentrations of VOC were measured at two ventilation rates in both nonresidential buildings, and the data were applied to a single-equation, mass-balance model. Apparent specific source strengths for VOC approximately doubled with a six-fold increase in ventilation rate.
A Computer-Controlled System for Measuring Ventilation Rates of Buildings Using Sulfur Hexafluoride as a Tracer Gas
Authors: Alevantis LE
Published: December 2008

A computer-controlled system for measuring ventilation rates in large buildings is described. The system consists of a data acquisition unit controlled by a personal computer, a gas Chromatograph equipped with a molecular sieve column, a scandium-tritide electron capture detector (ECD), a weather station, and a carbon dioxide analyzer. One of the unique features of this system is that it prevents oxygen from entering the ECD, thus reducing the minimum time between samples and considerably extending the life of the detector. The system is capable of monitoring up to 16 different locations, automatically calibrating itself, and displaying ventilation rates using the decay method at the end of the sampling period. The tracer gas is injected with a syringe in the heating, ventilating, and air-conditioning (HVAC) return air.
Novel Techniques in Fossil Fuel Mass Spectrometry
Authors: Wood KV , Ashe TR
Published: December 2008

Description

Developments in the application of new ionization and new separation techniques that have become standard analytical mass spectrometric capabilities.
Skiing Trauma and Safety: Seventh International Symposium
Authors: Johnson RJ , Mote CD , Binet M-H , Binet M-H
Published: December 2008

Description

Research findings and expert opinion on the problem of snow skiing injury. 39 papers cover: epidemiology of skier injuries; skier behavior, ability, and conditioning; specific skier injuries; ski boot mechanics; binding mechanics; biomechanics of the lower extremity in skiing; biomechanics of thumb injuries; skiing safety; biomedical testing; and clothing.
Automated Procedure for Creating Flight-by-Flight Spectra
Authors: Denyer AG
Published: December 2008

This paper presents a functional description of a versatile computer program developed to provide rapid response to spectrum generation requirements. The program, when supplied with flight profiles and the distribution of those profiles during the aircraft lifetime, will create a randomly sequenced flight-by-flight spectrum in terms of load factors, loads, or stress at a specific structural location.

The heart of the program is a data base containing the frequency definition of load factor occurrences representing the gust and maneuver load cycles for various flight segments. This paper discusses the establishment of the data base from data published in MIL-A-87221 and the FALSTAFF reports, from analytically derived load factor data and from flight load records from specific aircraft. The various forms of load factor data acceptable to the program, namely, exceedance curves, range/mean tables, and the FALSTAFF methodology, are discussed as to advantages and disadvantages.

The program will accept multiple flight profiles each with multiple flight segments defined by segment title, segment time, and selected significant flight parameters such as gross weight, Mach number, altitude, and aircraft geometry. For each profile, the procedure creates a series of individual flight load factor spectra each of which differs from all others in load sequence and magnitude while maintaining the sequence of the flight segments. The spectra include the infrequent high loads randomly selected from within the statistics of the data base. Load-factor spectra to stress spectra conversion is briefly discussed in terms of the program capability.

The output spectrum is a series of flights representing a defined period of usage with the flights representing the various profiles randomly sequenced within the supplied distribution statistics. The spectrum form is suitable for direct input to fatigue or crack growth programs or can be output to tape for submittal to a fatigue testing machine.
Tracking Time in Service Histories for Multiaxis Fatigue Problems
Authors: Conle FA , Oxland TR , Wurtz D , Topper TH
Published: December 2008

Techniques are presented for the acquisition, reduction, storage, and retrieval of time-sequenced, multi-channel, service load information. The relative merits of other methods are discussed and the advantages of time information demonstrated in a component analysis example.
Calculation and Experimental Analysis of Forces and Stresses in Intramedullary Nail Models
Authors: Baumgart F , Becker HJ
Published: December 2008

One open cylindrical tube made from shape memory alloy of 55% nickel and 45% titanium (NiTi) was tested. The activated total radial force was measured between rigid plates, when the tube was heated by hot water. Three NiTi tubes of 10-mm length were inserted into biomechanical equivalent aluminum tubes and heated in order to measure the deformation of the model tubes. Photoelastic tests were performed on three NiTi tube specimens, 2.5 mm in length, which had been inserted into biomechanical equivalent Araldite disks of 10-mm thickness. All tests were evaluated by combining the results with calculations on slender circular rings and were transmitted to natural bone tubes. The results show activated stresses between 15 and 30 N/mm2 in real bone and therefore no dangerous stress states.
Modeling the Insertion of a Zickel Rod into the Femur
Authors: Hoffman AH , Daly A-M , Olivieri SA , Tarquinio TA
Published: December 2008

A computer-aided design (CAD) system was used to model the insertion of a Zickel rod into a femur. Results show that although the shape of the rod and the intramedullary canal match closely in the fully inserted position, a considerable geometric mismatch can occur during rod insertion. The location of the starting hole and the valgus bend at the proximal end of the rod shaft can combine to create high stresses in the trochanteric region. High stresses can also occur during insertion between the canal and the distal posterior rod surface. These phenomena are the likely causes of the intraoperative complications of trochanteric fracture and the difficulty experienced in readjusting the anteversion once a rod has been inserted. Redesign of the distal end of the rod could reduce the difficulty in readjusting the anteversion.
Comparison of Interlocking and Noninterlocking Intramedullary Nails in Bending and Torsion
Authors: Bechtold JE , Schaffhausen JM , Kyle RF , Gustilo RB
Published: December 2008

Two types of interlocking intramedullary (IM) nails and a noninterlocked IM nail were tested in bending and torsion, to compare their flexural stiffness, and torsional stability in a femoral fracture model. A Grosse-Kempf IM nail with proximal and distal cortical interlocking screws, a Brooker-Wills IM nail with proximal interlocking screw and distal cancellous interlocking fins, and a Grosse-Kempf IM nail with no interlocking screws were tested. All IM nails had similar flexural stiffnesses. The interlocked Grosse-Kempf IM nail was most stable in torsion, followed by the interlocked Brooker-Wills IM nail. The noninterlocked Grosse-Kempf IM nail was least stable in torsion.
The Brooker-Wills Femoral Nail: Technical Difficulties and Their Avoidance
Authors: Blumberg KD , Hanks GA , Foster WC , Cardea JA
Published: December 2008

Eighty-seven femur fractures treated with the Brooker-Wills distal fin deployment interlocking nail were analyzed for intraoperative technical problems. Only unstable fractures located distal to the lesser trochanter and proximal to a level 5 cm proximal to the distal epiphyseal scar were included. Seventeen fractures were subtrochanteric, 19 were comminuted diaphyseal, and 51 were subisthmal. The majority (73) were locked proximally and distally. Of the 87 procedures, 33 technical difficulties occurred in 24 cases, for an overall rate of 29%. These ranged from problems with fin deployment and proximal screw insertion to bending of the nail itself. Patient position and proper technique were significantly correlated with the incidence of technical difficulties.

Postoperative complications were few, with one angulatory malunion, five nonunions, two unacceptable shortenings, and no deep wound infections. Average healing time was 12 weeks. The nail functioned well in regard to fracture healing, which was not affected by the technical difficulties. A significant learning curve for nail insertion was demonstrated. The authors concluded that most of the problems encountered could be avoided by strict adherence to suggested technical details and lateral patient positioning.
Intramedullary Nailing of Femoral Shaft Fractures Using the Hansen-Street Nail
Authors: Stein D , Proano F , Johanson P , Stryker W , Kim W
Published: December 2008

This is a retrospective study of 211 consecutive femoral shaft fractures treated with intramedullary nailing using the solid, diamond-shaped Hansen-Street nail. The pre-bent nail was inserted into the broached femoral canal with the aid of image fluoroscopy and with closed reduction in 168 cases, with an average operating time of 1.7 h and blood loss of 75 cc. Open technique was performed in 43 cases. The average follow-up was 13.7 months; there were no nonunions. The time to bony union by bridging callus was 4.1 months. Length stability correlated with the degree of comminution and the fracture site location. Shortening greater than 2 cm was found in 1.4% of the cases. Malrotation greater than 10 deg occurred in 2.1% and infection in 1.8% of patients. The Hansen-Street nail provides a simple and versatile bone-implant complex and is somewhat unique in affording some rotational control by the press fit of the diamond-shaped nail in the prebroached medullary canal. This end-result study reveals gratifying clinical results without sacrificing the medullary contents and some endosteal cortex, which results from intramedullary reaming.
Rush Pin Intramedullary Fixation of Transverse Diaphyseal Femoral Fractures
Authors: Brueckmann FR
Published: December 2008

The Indiana series is a series collected from 27 different surgeons, of 387 transverse diaphyseal femoral fractures, similarly classified and treated with nonreamed, 6.35-mm (1/4 in.) precurved Rush pins, is reported. Insertion sites are the lateral femoral condyle or greater trochanter. Reduction prior to surgery is accomplished with a special extension table with a knee support. Ninety percent of the fractures were pinned by closed technique. Open fractures occurred in 4.6% of the patients and were treated similarly. No persisting infection on nonunion was detected. Malalignment in external rotation or valgus or both was present in 1.3% of patients. Healing to painless weight-bearing is usually between ten and twelve weeks.
Mechanical Complications Following Interlocking Femoral Nailing
Authors: Wiss DA , Brien W
Published: December 2008

Two hundred and sixty-two fractures of the femoral shaft were treated with the Grosse-Kempf interlocking nail. Mechanical complications occurred in 26 cases (10%): There were five broken nails (2%), four bent nails (1.5%), four proximal screw failures (1.5%), and thirteen major torsional deformations of the nails (5%). Four of the five broken nails were in previously open fractures and were associated with nonunion of the fracture. Two of the nails broke at the junction of the proximal threaded conical portion and the slot in the nail, one occurred at the nonunion site, and two occurred through the proximal of the two distal screw holes. Eccentric portals of entry led to nail deformation in two patients, and additional trauma led to bending in two other patients. There were four failures of the proximal interlocking screw; three of the four broken screws occurred in comminuted subtrochanteric femur fractures treated with static locked nails. Minor degrees of torsional deformation of the nail were seen in up to 50% of the cases. However, major torsional deformation was seen in only 13 patients (5%). Mechanical complications following locked nailing appear to be acceptably low. Their enormous clinical efficacy appears to justify their continued use.
Assurance of the Pressure Vessel Integrity with Respect to Irradiation Embrittlement: Activities in the Federal Republic of Germany
Authors: Kussmaul K , Fëhl J , Weissenberg T
Published: December 2008

Safety research of light water reactor pressure vessels in the Federal Republic of Germany (FRG) is presently focused on validation programs based on fracture mechanics concepts which study irradiation embrittlement, pressurized thermal shock, and cyclic crack growth under operating conditions. Crack initiation values derived from the JR-curve could be confirmed as reliable material property to enable transferability of results from small specimen testing to complex structures.

For validation of irradiation surveillance practice, trepans were taken from a forged shell course of a commercial reactor pressure vessel wall to compare material degradation of the wall with that of the surveillance specimens and to establish properties through the thickness of the wall. The experimentally determined amount of reduction in toughness of the vessel wall depends strongly on the orientation of the specimens with respect to the main forging direction of the hot formed material. The degradation of the material with respect to transition temperature shift and upper shelf energy drop in Charpy impact tests could not be predicted conservatively on the basis of the existing trend curves in the U.S. Code of Federal Register. On the other hand, the gradient of embrittlement measured in short distances from the inner to the outer surface of the vessel wall is much less and therefore less important than assessed in the proposed revision of the U.S. Code.

Archive material representing the shell course from which the trepans were taken was irradiated in test reactors in the United States and the United Kingdom. The irradiated archive material shows a lower degradation than the vessel wall of the commercial reactor.
The Swiss Research Program on Irradiation Embrittlement and Annealing of Reactor Pressure Vessel Steels
Authors: Waeber WB , Njo DH
Published: December 2008

The present research program on irradiation embrittlement and annealing of reactor pressure vessel (RPV) steels in Switzerland is carried out at the Paul Scherrer Institute for Reactor Research. The particular program structure and its relation to the concept for an improved surveillance program is described.

Based on past experience with surveillance programs, especially for older plants, the main goal of the research program is determined by an effort to overcome identified shortcomings.Therefore the following topics are discussed: 1. Obtaining additional data to supplement those from specific surveillance capsules. 2. Understanding the mechanisms of irradiation embrittlement by microstructural investigations of the materials. 3. Investigations of the annealing-recovery behavior of irradiated RPV steels. 4. Validation efforts concerned with the transferability of test reactor and surveillance program results to the real RPV.

Within the framework of bilateral research agreements, participation in research programs coordinated by the International Atomic Energy Agency (IAEA), and collaborative research with other Swiss and foreign institutions, a review of past and future activities is presented; the technical facilities (irradiations, mechanical testing, physical methods) and the advanced and new tools used in the investigations, especially those for the microstructural studies, are outlined and put into perspective. Finally, first results obtained in the research program are summarized.
Development of Reactor Pressure Vessel Design, Neutron Fluence Calculation, and Material Specification to Minimize Irradiation Effects
Authors: Leitz C , Koban J
Published: December 2008

In the second decade of design and construction of water-cooled and watermoderated power reactors in the Federal Republic of Germany (FRG), the neutron irradiation effect on reactor pressure vessels (RPV) was reduced in a twofold manner: 1. Steel optimization for high toughness at the end of design life. 2. Fluence reduction by adaptation of core geometry and RPV diameter.

The methods of fluence evaluation and results for different core configurations are described. They provide a satisfactory fluence surveillance of the RPV. If necessary, operational measures are possible to reduce the end of life (EoL) fluence of the RPV. The provident fluence reduction measures taken in two older commercial power plants are described. These measures reduced the EoL fluence by more than a factor of two without loss of power.

The new generation RPV provides a larger water gap between core edge and RPV wall and therefore much lower EoL fluences. The design EoL fluence of all 1300-MWe and the modern 1000-MWe PWR is 5 × 10 18 cm -2 and 3.3 × 10 18 cm -2, respectively.

Fine-grain forged steels 22 NiMoCr 3 7 and 20 MnMoNi 5 5 and corresponding weldments are used for the RPV in KWU-built nuclear power plants. Extensive experience has been gained on the irradiation behavior of these steels. By specifying high purity, especially for the elements copper (Cu) and phosphorus (P), and by keeping Nickel (Ni) at medium levels, which improves preirradiation toughness but supports irradiation effect, high postirradiation toughness is maintained.

Therefore, in combination with the low EoL neutron fluences, the nil ductility transition temperature shift Δ T 41 was reduced by nearly 90% by comparison with the first generation plants (high fluence, high copper).
Effectiveness of Flux Reduction Measures Instituted at the Maine Yankee Atomic Power Station
Authors: Jones HF
Published: December 2008

Concern over the effect of radiation embrittlement of the reactor pressure vessel on heatup and cooldown pressure-temperature limits and pressurized thermal shock (PTS) resulted in a decision to implement low-leakage fuel management at Maine Yankee during the early 1980s. This paper provides background information leading up to this decision and describes the transition from standard OUT-IN to low-leakage fuel management. Various methods to determine the effectiveness of flux reduction measures are described and results compared. Results of cavity measurements and use of measurement results to (a) confirm effectiveness of flux reduction measures and (b) benchmark neutron transport calculations are also discussed. The results of neutron transport calculations are used to project fast neutron fluence and RTNDTs at expiration-of-license.
Radiation Embrittlement Trend Curves and the Impact on Nuclear Plant Operating Criteria
Authors: Odette GR , Griesbach TJ
Published: December 2008

Research to understand the mechanisms of neutron irradiation embrittlement of reactor pressure vessel steels has assisted in the development of improved radiation damage trend curves such as Regulatory Guide 1.99, Revision 2. Statistically calibrated, physically-based models of the embrittlement process have been derived which include the effects of variables such as copper, nickel, and fluence. The ability to accurately predict the amount of damage or embrittlement of the vessel is essential to the safe, continued operation of the plant. Operating criteria, such as the pressure and temperature limits, are determined for each plant in accordance with the margins established in Section III of the ASME Code. These curves must be updated periodically to account for the effects of embrittlement in terms of the nil-ductility reference temperature (RTNDT) shift. The application of the improved radiation damage trend curves, and the impact on plant operations, are discussed in light of the recent studies of the embrittlement phenomena.
SANS Investigation of Irradiated A533-B Steels Doped with Phosphorus
Authors: Beaven PA , Frisius F , Kampmann R , Wagner R , Hawthorne JR
Published: December 2008

Small angle neutron scattering (SANS) techniques have been employed to study the nature of the radiation damage and its dependence on phosphorus concentration at two different copper levels (0.002 and 0.3%) in a set of laboratory melts of A533-B steel irradiated to ˜2.5 × 1019 n/cm2 at 288°C under test reactor conditions. In all materials, distributions of clusters were found with number densities ˜ 1017 to 1018 cm-3 and diameters ˜ 1 to 2 nm. Cluster volume fractions were approximately an order of magnitude higher in the 0.3% Cu steels, which were associated with greater radiation strengthening and embrittle-ment. Magnetic and nuclear scattering data are best interpreted in terms of mixed clusters containing Cu, Mn, and Ni; increasing P content leads to some refinement of the cluster distributions. In the low-Cu steels embrittlement is also associated with radiation hardening via cluster formation promoted by increasing phosphorus content.
Positron Lifetime Characterization of Irradiated Pressure Vessel Model Alloys
Authors: Valo M , Huomo H , Nyberg P , Hautojarvi P
Published: December 2008

We have measured positron lifetimes in pressure vessel steel model alloys of A533-B and A302-B type, containing various amounts of Cu, Mn, Mo, and Ni alloying elements. Samples were prepared from broken halves of irradiated Charpy specimens used earlier for radiation sensitivity and composition interaction studies. The observed changes in the average positron lifetime seem to correlate well with changes in the alloy composition. A preliminary interpretation of the lifetime values is given.
Effects of Matrix Toughness on Fatigue Response of Graphite Fiber Composite Laminates
Authors: Simonds RA , Bakis CE , Stinchcomb WW
Published: December 2008

To evaluate the possible advantages of using a tough resin, polyetheretherketone (PEEK), as a matrix in a composite material, the fatigue response of (0/ +45/90/ −45)s4 AS4/ PEEK graphite-epoxy specimens with drilled center-holes subjected to constant amplitude, fully reversed cyclic loading was investigated. The results were compared with those of a similar investigation using T300-5208 graphite-epoxy specimens to determine the effects of matrix toughness on fully reversed fatigue.

Several load levels provided for lives between 104 and 107 cycles to establish baseline (R = − 1) S-N curves for the two materials. Additionally, damage evaluation methods such as stiffness monitoring, penetrant-enhanced radiography, and residual strength measurements were used to identify damage mechanisms; to monitor damage growth process; and to establish relationships between damage and strength, stiffness, and life of the specimens.

Damage initiated at the hole in all cases, but the damage modes, their subsequent growth and interaction, and their effects on fatigue response were dependent on cyclic load levels and material. Damage in the brittle 5208 matrix specimens consisted of matrix cracks followed by delamination. Over the range of fatigue lives studied, the residual tensile strengths of the 5208 matrix specimens were greater than the initial notched tensile strength. During loading the compressive strength degraded to values less than initial notched compressive strength, and the fatigue failure modes were compressive. Similarly, at the lower cyclic load levels, corresponding to lives between 105 and 107 cycles, the PEEK specimens also suffered matrix cracking, delamination, and an attendant compressive stiffness loss. The specimens failed under the compressive portion of the cyclic loading. However, at higher cyclic loads, 0° fiber damage in the PEEK specimens was observed in addition to matrix damage, and the tensile stiffness degraded. The failure modes were tensile in these cases.

The results of this study show that matrix toughness influences the long-term behavior of graphite fiber composites. Although similar matrix damage modes were observed in the two material systems, the consequences of the damage, as measured by strength, life, and failure mode, were not similar.
Consideration of Environmental Conditions for the Fatigue Evaluation of Composite Airframe Structure
Authors: Berg M , Gerharz JJ , Gökgöl O
Published: December 2008

This paper reports on experimentally derived compensation factors to account for missing environmental history (temperature and humidity) during fatigue testing of large composite structures (components). Compensation factors are either factors by which the fatigue load level of component fatigue tests is increased or by which the required residual strength has to be increased if preloading did not include environmental history.

Preconditioned coupon specimens were subjected to accelerated quasirealistic mechanical and environmental flight-by-flight loading, and other coupon specimens were loaded exactly like the composite airframe structure (that is, with less complete simulated environment). Temperature and moisture content in residual strength testing were the same for surviving coupon specimens and the composite airframe structure. Corresponding to composite airframe structures of the Tornado and the Airbus fin box, the materials involved were the 175°C curing systems Ciba 914C and Fiberite 1076 E, and the 125°C curing systems Ciba 913C and Hexcel F550 with T300 carbon fibers in all resins. Different types of laminates and specimens were used to generate predominantly matrix shear stresses or fiber normal stresses within the coupon specimens.

At present design load levels, the fatigue life to be proven was reached without failures of the coupon specimens subjected to the flight-by-flight load conditions of the component test or to quasirealistic combined mechanical and environmental loading. Only small differences in residual strength were noticed among the surviving specimens. At higher fatigue load levels the superimposed more complete environmental test conditions decreased the life to failure significantly, by factors between 1.5 and 9.1.
The Influence of Fiber, Matrix, and Interface on Transverse Cracking in Carbon FiberReinforced Plastic Cross-Ply Laminates
Authors: Peters PWM
Published: December 2008

The transverse tensile strength of a unidirectional laminate is generally accepted as a material property. The transverse strength of a single ply in angle-ply laminates is influenced by the neighboring layers (effect of constraint) and is for this reason not a material property. In the present investigation of four different carbon fiber-reinforced plastics (CFRP) this influence of constraint and the effect of fiber, matrix, and interface on transverse cracking are investigated. An intermediate ductile resin system proved to increase the transverse strength significantly (if the fiber matrix bond is good) in comparison with a brittle resin system. A highly ductile matrix (polyetheretherketone—PEEK), however, did not further or additionally improve the transverse strength significantly. The intermediate ductile resin system proved to be sensitive to the formation of voids under the cure conditions applied. The inhomogeneous distribution of voids disturbed the expected constraining effect.
Characterization of Matrix Toughness Effect on Cyclic Delamination Growth in Graphite Fiber Composites
Authors: Mall S , Yun KT , Kochhar NK
Published: December 2008

Three composite systems, having different interlaminar fracture toughnesses, were tested to characterize the matrix toughness effect on delamination growth behavior in composites under fatigue loading. With each composite system, three specimen types were tested: (1) double-cantilever-beam, (2) cracked-lap-shear, and (3) end-notched flexure specimens for mode I, mixed mode I-II, and mode II loadings, respectively. The measured delamination growth rate data were correlated with the corresponding strain energy release rates, GI, G(I−II), and GII. The cyclic delamination growth resistance of composites, expressed in terms of static interlaminar fracture toughness, that is, ΔG/GC, decreases with increasing matrix toughness. And this decrease depends on the loading mode. Further, this decrease in cyclic delamination growth resistance of composites, expressed in terms of normalized interlaminar fracture toughness (ΔG/GC), increases when fatigue loading mode is changed from mode I through mixed mode I-II to pure mode II.
Delamination Failure Modes in Filament-Wound Composite Tubes
Authors: Foral RF , Gilbreath DR
Published: December 2008

Filament-wound composite tubes of helical hoop construction were tested in axial tension at room temperature and at elevated temperatures. Stress analysis of such tubes shows the presence of tensile interlaminar stresses, tending to produce delamination. The test results show that delamination failures do occur, and that material performance depends on laminate stacking sequence as well as test temperature. In specimens with no inside hoop layers, the tensioned inside helical fibers pulled away from the laminate in a localized delamination failure mode, called transverse fiber pullout. The predicted interlaminar stresses at which this occurred are considerably lower than the expected through-the-thickness strength. The interlaminar stresses producing these failures must be accounted for in design of curved laminates, because they can produce premature failure at a load level substantially below that predicted by in-plane analysis.
Fracture of Pressurized Composite Cylinders with a High Strain-to-Failure Matrix System
Authors: Saeger KJ , Lagace PA
Published: December 2008

An experimental and analytical investigation was conducted to examine the fracture behavior of pressurized graphite/epoxy cylinders and coupons that utilize a high strain-to-failure matrix system. The material system is a five-harness satin-weave cloth made of Hercules AS4 fiber impregnated with American Cyanamid's CYCOM 907 epoxy. Tests were performed on standard tensile coupons to determine the elastic constants of the material and the notched and unnotched fracture characteristics of a quasi-isotropic (0,45)s laminate of this material system. Two notch types, holes and slits, were examined, and existing failure criteria were explored as means to extrapolate these coupon data to the prediction of the failure pressures of axially slit cylinders, which were also tested. The fracture characteristics of this composite system were compared to a baseline system with Hercules 3501-6 epoxy. In the laminates using the "tough" matrix system, delamination was not a significant damage mode. Previous work had shown localized delamination in the 3501-6 laminates. However, both the coupon tests and the cylinder tests indicate that this high strain-to-failure matrix system is more notch sensitive than the baseline epoxy system with the relatively brittle 3501-6 matrix.