bluuebunny/crossref_metadata_2025 huggingface dataset:
Prostaglandin E2 Synthesis by the Tissue Surrounding Ultrahigh Molecular Weight Polyethylene in Different Physical Forms
Authors: Goodman SB , Chin RC , Chiou SS , Lee JS
Published: March 2009

Twenty mature, New Zealand white, female rabbits were divided into three groups. Using sterile technique, a 6-mm drill hole was made in the proximal tibia bilaterally. The marrow was scooped out underneath the hole. In Group 1, the left tibia received a bulk pellet of ultrahigh-molecular-weight polyethylene (UHMWP). The right tibia received UHMWP particles averaging 67 μm. In Groups 2 and 3 the right tibia received UHMWP particles averaging 16 μm. The left tibia functioned as a drilled, but nonimplanted, control. The animals in Groups 1 and 2 received regular water ad libitum. The animals in Group 3 drank water in which naproxen sodium was dissolved (1.375 mg/mL). The animals were killed at 16 weeks postoperatively. An equal volume of medullary canal contents was harvested sterily from the right and left tibia in each animal and maintained in tissue culture. The cumulative collection of tissue culture supernatants over a 3-day period was assayed for prostaglandin E2 (PGE2) by radioimmunoassay. Specimens from Group 1 produced on average 54.45 ± 12.77 ng PGE2 on the right side, and 65.85 ± 22.32 ng PGE2 on the left side [not significant (NS)]. The polyethylene (PE) particles were relatively large and could not undergo phagocytosis; these particles did not stimulate increased PGE2 production in comparison with bulk implants. Specimens from Group 2 produced 72.15 ± 13.60 ng PGE2 on the right side and 67.53 ± 16.59 ng PGE2 on the left side (NS). Specimens from Group 3 produced 28.40 ± 4.54 ng PGE2 on the right side and 33.30 ± 7.69 ng PGE2 on the left side (NS). Naproxen sodium significantly reduced PGE2 production on both the right and left sides in Group 3 compared with Group 2 (P < 0.05). UHMWP particles and PGE2 production have been implicated in the periprosthetic bone lysis associated with aseptic loosening in humans.
In Vitro Activation of Monocyte Macrophages and Fibroblasts by Metal Particles
Authors: Goldring SR , Bennett NE , Jasty MJ , Wang J-T
Published: March 2009

Several reports have documented the presence of focal bone lysis and aseptic loosening in patients after total hip replacement using noncementing techniques. A fibrous tissue reaction with histiocytic infiltration associated with metal debris adjacent to the femoral component has been described. The authors have used cell culture models to study the effects of metal particles on human monocyte/macrophages and connective tissue cells in order to define the potential mechanisms responsible for these clinical findings. We show that titanium, titanium alloy (Ti-6Al-4V), or cobalt-chrome-molybdenum particles activate monocyte/macrophages to release prostaglandin E2 (PGE2) and directly stimulate fibroblasts to increase collagen synthesis. These observations provide a potential mechanism by which the release of metal particulate debris could induce a fibrous connective tissue reaction and focal bone lysis at the bone/implant interface after noncemented total hip replacement.
In Vitro Cellular Activation by Fabricated and Clinically Retrieved Bone Cement Wear Particles
Authors: Emmanual J , Emmanual JG , Hedley AK
Published: March 2009

Bone cement particles were retrieved by enzyme digestion of membranes from revision arthroplasty procedures. These clinically retrieved particles were compared with bone cement particles fabricated in the laboratory using Howmedica's Simplex P bone cement. Three particle sizes, ranging from 230 to 380 μm, of both retrieved and fabricated bone cement were placed in cell cultures, consisting of homogeneous populations of B cells, T cells, macrophages, and fibroblasts. After an incubation of 72 h, the culture supernatant was assessed for levels of interleukin 1 (IL-1) and prostaglandin E2 (PGE2) by an enzyme-linked immunosorbent assay (ELISA) technique.

The fabricated particles showed higher levels of PGE2 in all sizes when compared with the retrieved particles. Fibroblasts showed a significant increase in PGE2 with both retrieved and fabricated particles in comparison with other cell types. There were no differences in IL-1 levels between the fabricated and retrieved bone cement particles.

In this cell culture system, fibroblasts seem to be potent producers of PGE2 secretion, regardless of the shape or size of the particles.
Polymer Particles In Vivo: Distribution in the Knee, Migration to Lymph Nodes, and Associated Cellular Response Following Anterior Cruciate Ligament Replacement
Authors: Macon ND , Lemons JE , Niemann KMW
Published: March 2009

The objective of this study was to determine histologically the local and systemic soft tissue responses to polymeric particulate generated by mechanical degradation of prosthetic anterior cruciate ligament (ACL) devices in a canine model. Following gross observations at ligament retrieval, samples of synovial, meniscal, cartilage, and inguinal lymph node tissues were collected and processed for standard hematoxylin and eosin staining. Tissues within synovial capsules of stifle joints showed osteophytes and other osteoarthritic changes in response to all implant and control interventions. The particulate quantity and size distributions were determined using a computerized image analysis system, employing light and polarized light microscopy techniques. Particles generated from ACL devices elicited nondebilitating chronic synovitis in the joint capsule and a mild inflammatory response in inguinal lymph nodes for up to approximately one year in vivo. Statistically significant relationships were found between the particle quantity and tissue type, the size and tissue type, and the quantity and time in vivo.
Usefulness of Accelerated Test Methods for Sealant Weathering
Authors: Fedor GR
Published: March 2009

Sealant test samples were exposed to accelerated and outdoor weathering to determine the usefulness of accelerated weathering test methods in predicting material degradation. One formula from seven different generic sealant types were exposed to three different outdoor environments for two years. Identical samples were exposed to three different accelerated test methods for 2000 hours. The degradation from outdoor exposure in terms of appearance, cracking, and change in hardness was duplicated in each case by at least one of the accelerated test methods.
Accelerated Weathering and Heat Stability of Various Perimeter Sealants
Authors: Bridgewater TJ , Carbary LD
Published: March 2009

All perimeter sealants do not react the same when exposed to long term UV and extreme heat caused by the environment. The resistance to weathering is achieved by the inherent nature of the sealant polymer system. Some manufacturers achieve some degree of resistance to weathering by the use of fillers which shade the polymer from the UV and others use chemical additives to absorb the UV radiation and protect the polymer system. This paper will look at combinations of deteriorating mechanisms and give some indication as to the key factors causing the deterioration or sealant changes with the sealants studied. Some urethanes were shown to revert back into their original liquid state during UV exposure where the silicones did not. By the use of accelerated weathering lab equipment and lab ovens, the detrimental physical effects were demonstrated on various two-part urethane and one-part silicone perimeter sealants currently used in construction. Tensile adhesion data, durometer and visual observations are reviewed following a specific exposure time. This testing evaluation showed a faster sealant degradation with heat and ultraviolet light when compared to cyclic UV and condensation cycles with UVB313 bulbs. No significant degradation occurred with samples exposed to 100% humidity at 30°C (86°F) or 50°C (122°F) with the exception of loss of adhesion to the precast concrete. This study provides the framework of a test method to screen perimeter sealants for durability and reversion resistance.
Accommodation of Movement within Building Seals and Sealants for Highrise Tower Architecture and Construction
Authors: Yanoviak AC
Published: March 2009

This manuscript includes an overview of architectural design research on the subject of cyclical and non-cyclical ‘movement systems’ encountered in the design and construction of highrise building towers. Furthermore, it takes into consideration the need for structural ‘accommodation’ and ‘resistance’ of these multiple movements and ‘movement systems’ in the design, manufacture, application and maintenance of ‘building seals and sealants’.

This presentation includes a basic review of architectural and structural design factors, building codes and standards for the effects of both ‘live load’ and ‘dead load’ on the structural building frame and ‘exterior building envelope’. It also addresses the application of appropriate construction materials and building systems including ‘cladding and glazing systems’. Due consideration is given to the development of design standards and the standard design details required, to accommodate these movements. The accumulative single and multiple effects of wind and seismic forces, as well as gravity and thermal loads are also addressed.

Practical examples of water infiltration problems and inadequate design details, specifications, material applications, waterproofing methods and challenges are noted. References to ‘building seals and sealants’, including the phenomena of ‘curing’, ‘creep’, ‘elongation’, ‘elasticity’, ‘plasticity’, ‘yield limits’, ‘electrolysis’ ‘stress’, ‘strain’, ‘fatigue’, ‘adhesion’, ‘cohesion’, and ‘bonding’, are also presented. Maintenance factors to be considered in remedial repair specifications, design details and installation methods, are also referenced in this manuscript.

Design challenges by architects, developers, and building owners for contractors and manufacturers of ‘building seals and sealants’ are also noted.
Applicability of Artificial Weathering Tests for Performance Evaluation of Elastomeric Sealants
Authors: Minkarah I , Cook JP , Rajagopal AS
Published: March 2009

A number of sealant samples, Silicone, D1190, D3405 and other designations, were subjected to the standard battery of ASTM tests used in Ohio for acceptance of sealant materials. In addition, non-standard tests such as artificial weathering, cyclic shear/tension, stress relaxation, creep and modulus of elasticity were carried out on samples of the same materials. The results of the investigation revealed that the standard tests are not sufficient by themselves to characterize the long time behavior of the sealants. This paper presents the results of the artificial weathering tests with a brief description of the others. The artificial weathering tests were carried out for 608 hours and the samples were examined by way of color, surface characteristics, movement of sample, flexibility and hardness. Most of the samples passed the standard tests. However, despite the short duration of exposure in the weathering tester, there were significant differences in the ability of different materials to withstand the artificial weathering. In general, the D3405 materials survived the weathering test well, but they did show some scaling after 608 hours. The D1190 materials were uniformly poor, with some flowing off the exposure panel. Silicone gave the best performance, showing very little effect after 608 hours. The authors recommend continued studies to determine an appropriate exposure time so that the weathering test may be added to the standard bank of tests for elastomeric sealants.
Effect of Early Joint Movement on Oxime Silicons Sealants and Comparison to Other One-Part Silicone Systems
Authors: Flackett DR
Published: March 2009

Two separate investigations are discussed concerning effect of early joint movements. 1. Continuous Cycling While Curing The overall physical properties of sealants cured in a joint undergoing continuous +/- 10% deformation for one week are compared to those of sealants cured under static conditions. Acetoxy, benzamide, alkoxy and oxime systems were studied. 2. “Crack Test” Freshly prepared joints of different formulations were elongated to 25% of their original width starting 15 minutes after preparation. The effect on the surface and body of the sealants as well as the displacement from substrate was observed.

This test, the so called “crack test” was performed on acetoxy, benzamide, alkoxy, amine, and oxime.
Effect of Oxidizing Environments on Long-Term Performance of Rotationally Molded XLPE Storage Tanks
Authors: Wachob HF , McGarry FJ , Abell GH
Published: March 2009

Caution should be used when evaluating the long-term storage capability of polymeric materials in direct contact with chemically active solutions. Degradation and cracking of rotomolded, cross linked polyethylene (XLPE) storage tanks that have been used for long-term storage of potentially strong oxidizing liquids have been analyzed. Fractographic, mechanical and chemical evidence indicates that under certain conditions XLPE can be severely oxidized and degraded when concentrated industrial bleach or oxidizing acids decompose or react with the XLPE.
Real-Time Measurement of Small-Crack Opening Behavior Using an Interferometric Strain/Displacement Gage
Authors: Sharpe WN , Jira JR , Larsen JM
Published: March 2009

A procedure for real-time measurement of the opening displacement of small fatigue cracks is reviewed. The method employs a computerized, laser-based, interferometric strain/displacement gage (ISDG) to monitor the relative displacement between two tiny indentations placed across small surface cracks. Complete load versus crack opening displacement curves are obtained for surface cracks of length ranging from 50 μm to several millimetres. The method is applicable to naturally or artificially initiated cracks in smooth or notched specimens. The load-displacement measurements provide a detailed record of crack closure behavior, and estimates of crack size are obtained from measurements of elastic compliance. The resolution of the opening displacement measurements is on the order of 5 nm. Computerization of the system allows measurements to be obtained in real time, facilitating feedback control of testing.

Four versions of the ISDG that are used in different laboratories are described. The instrument's characteristics are presented along with some practical considerations associated with its use. Examples from studies of a number of materials are included to demonstrate applications of the ISDG to the measurement of closure, crack shape, and to automation of small-crack testing.
ASTM Standards Associated with PWR and BWR Power Plant Licensing, Operation and Surveillance
Authors: McElroy WN , McElroy RJ , Gold R , Lippincott EP , Lowe AL
Published: March 2009

This paper considers ASTM Standards that are available, under revision, and are being considered in support of Pressurized Water Reactor (PWR) and Boiling Water Reactor (BWR) Nuclear Power Plant (NPP) licensing, regulation, operation, surveillance and life attainment. The current activities of ASTM Committee E10 and its Subcommittees E10.02 and E10.05 and their Task Groups (TG) are described. A very important aspect of these efforts is the preparation, revision, and balloting of standards identified in the ASTM E706 Standard on Master Matrix for Light Water Reactor (LWR) Pressure Vessel (PV) Surveillance Standards. The current version (E706-87) of the Master Matrix identifies 21 ASTM LWR physics-dosimetry-metallurgy standards for Reactor Pressure Vessel (RPV) and Support Structure (SS) surveillance programs, whereas, for the next revision 34 standards are identified. The need for national and interna tional coordination of Standards Technology Development, Transfer and Training (STDTT) is considered in this and other Symposium papers that address specific standards related physics-dosimetry-metallurgy issues.
Passive Temperature Monitoring in Reactor Environments Using Integrating Thermal Monitors
Authors: Ruddy FH , Seide JG , Fero AH
Published: March 2009

A new passive temperature monitoring device, the Integrating Thermal Monitor (ITM) has been developed for measurements in reactor environments. The operation of the ITM is based on the thermal annealing behavior of latent particle tracks in Solid State Track Recorders (SSTRs). Several SSTR materials have been identified which have time/temperature annealing sensitivities for latent tracks which match the environments of the nuclear power plant measurement locations of interest. Of these, nine ITM materials have been calibrated at constant temperatures of 30, 40, 50, 60, 70, 80, 90, 100, 150, and 175 °C for periods ranging from hours to more than 4 years. Detailed response measurements have been obtained for more than 600 ITM samples to establish a calibration data base against which ITM response can be measured. A model has been developed for ITM response as a function of time and temperature, and this model is used to interpret the response of ITMs deployed at power reactors. Methods for using ITMs to determine Arrhenius Equivalent Temperatures for equipment components operated in unknown temperature environments are described, and ITM performance to date in nuclear power plant applications is also summarized.
The Materials Dosimetry Reference Facility
Authors: Hawari AI , Venkataraman R , Fleming R , Charles E , Grundl J , McGarry ED
Published: March 2009

The Materials Dosimetry Reference Facility (MDRF) is a new reactor-driven reference neutron field for reactor dosimetry calibrations and methods validation. Basically, the facility design is a steel cylinder (15-cm o.d., 5-cm i.d.) mounted in the pool close to the core of the Ford Nuclear Reactor at the Phoenix Memorial Laboratory of the University of Michigan. Two spectrum options are available: one with a near-1/E distribution below 0.1 MeV, and the other with a 10B filtered spectrum that cuts off below 4 keV. Fast-neutron fluence rates (nominally 2.8×l011cm−2s−1, E>1 MeV) are established by means of neutron fluence transfer from the 252Cf Fission Neutron Irradiation Facility at NIST. Neutron fluences for sample irradiations (conventional maximum 2×l016n/cm2, E>1 MeV) will be certified to uncertainties of ±(5−6)%, lσ. The neutron spectrum in the facility is established on the basis of neutron transport calculations and spectral index measurements, the latter with threshold, low-energy activation, and fission reactions. The results of calculations and measurements are reported in this paper.
Neutron Spectrum Effect on Pressure Vessel Embrittlement: Dosimetry and Qualification of Irradiation Locations in Osiris and Siloe Reactors
Authors: Alberman A , Beretz D , Bourdet L , Carcreff H
Published: March 2009

Two irradiation experiments have been undertaken in OSIRIS (Saclay) and SILOE (Grenoble) reactors, in order to establish the correlation between the embrittlement of pressure vessel steels and neutron spectrum. Target fluence is 0.1 dpa for both experiments. This damage fluence corresponds to a fluence of 7.5 1019 n.cm−2 E>1 MeV (7.5 1015 n.m−2) in the case of a well moderated light water spectrum, but only 4 5 1019 n.cm−2 in the case of the specially designed SILOE irradiation location. One irradiation run is now completed, the second one is underway. This paper presents the experimental dosimetry data and irradiation parameters obtained in the preliminary qualification program, needed to assess this damage correlation.
Calculation of Transmutation in Copper and Comparison with Measured Electrical Properties
Authors: Greenwood LR , Garner FA , Edwards DJ
Published: March 2009

Calculations of the transmutation of pure copper have been performed for the Fast Flux Test Facility/Materials Open Test Assembly (FFTF/MOTA) and for the STARFIRE first-wall fusion reactor. The principal transmutation products in decreasing order of importance are nickel, zinc, and cobalt. Contrary to previously published calculations, nickel and zinc are produced at nearly equal rates in FFTF, but cobalt is insignificant. The fusion reactor case shows much higher transmutation rates and produces about twice as much nickel as zinc. Transmutation rates for FFTF were determined using adjusted neutron energy spectra based on dosimetry measurements at various positions in the MOTA. The predicted transmutation rates were compared directly with nickel concentrations measured by Energy Dispersive X-Ray Spectrometry (EDS) microchemistry and with measurements of the electrical conductivity of copper and two copper alloys irradiated in the MOTA. Measurements and calculations agree within ±15%.
Energy and Spatial Distribution of the Photoneutron Flux from a Radiotherapy Electron Accelerator
Authors: Agosteo S , Foglio Para A
Published: March 2009

An analytical method accurately describing the energy and the spatial distribution of the photoneutron flux in a radiotherapy room is reviewed by taking into account the influence both of different materials and thicknesses of the accelerator shield and of the composition of the walls of the radiotherapy room. This dependence is investigated by means of Monte Carlo simulations which also provides a validation of the method. The resulting formulas are employed to estimate the neutron production yield from flux measurements by means of activation detectors. The results of the measurements performed around some linear accelerators of the present generation have shown that the mean emission rate is of the order of 1011 neutrons per second.
Nuclear Data Needs for Fission Reactor Decommissioning
Authors: Kocherov NP
Published: March 2009

Calculations of radioactive inventories in fission reactor components for decommissioning purposes were reviewed at the International Atomic Energy Agency (IAEA) Advisory Group Meeting on “Nuclear Data Required for Fission Reactor Decommissioning” in Vienna, September 1992. Details of neutron transport calculations through pressure vessel and bioshield necessary to determine fluxes and spectra at these locations were discussed. In contrast to embrittlement studies the main interest for this problem is in accurate description of transport of thermal neutrons. The codes and data libraries used by the specialists in this field were identified. Actions necessary to improve the accuracy were agreed upon. Procedures for calculating activation of materials in reactor components were also assessed. The need for compilation of a special data library and a benchmark testing of libraries together with available codes against an experimentally measured data for a real plant at the decommissioning stage was established. Phase 1 of such a benchmark exercise is now under preparation at the IAEA.
Measurement of 233U Fission Spectrum-Averaged Cross Sections for Some Threshold Reactions
Authors: Kobayashi K
Published: March 2009

The 233U fission spectrum-averaged cross sections for twelve threshold reactions were measured relative to the average cross section of 0.688±0.040 mb for the 27Al(n,α)24Na reaction. The reference value was obtained by calculation using the energy dependent cross section in the Japanese Evaluated Nuclear Data Library (JENDL) Dosimetry File and the Watt-type fission spectrum in ENDF/B-VI. General agreement was seen between the measured and the calculated fission-spectrum averaged cross sections. However, there exist discrepancies of more than 10 % between the measured and the calculated average cross sections for the 24Mg(n,p)24Na, 47Ti(n,p)47Sc, and 64Zn(n,p)64Cu reactions. The tendencies in the calculated-to-measured ratios are similar to those for 235U fission spectrum-averaged cross sections we previously measured.

The measured average cross sections were also applied for the spectrum adjustment of the 233U fission neutrons using the Neutron Unfolding Package Code (NEUPAC). The adjusted spectrum is close to the Watt-type fission spectrum of 233U within the uncertainties of the obtained spectrum, although there exist some fluctuations in the ratio spectrum of the adjusted to the Watt-type.
Zirconium Alloy Performance in Light Water Reactors: A Review of UK and Scandinavian Experience
Authors: Pickman DO
Published: March 2009

Various aspects of zirconium alloy development for light water reactors in the UK and Scandinavia are reviewed, including the contribution made by some unique nuclear testing facilities. Among the problems encountered were the irradiation enhancement of corrosion and hydrogen pickup, crud deposition, iodine-induced stress-corrosion cracking on power ramping, and severe cladding deformation in loss-of-coolant accident conditions. The causes and behavior of defects, including hydride defects and fretting corrosion, are discussed.
The Effect of Fluence and Irradiation Temperature on Delayed Hydride Cracking in Zr-2.5Nb
Authors: Sagat S , Coleman CE , Griffiths M , Wilkins BJS
Published: March 2009

Zirconium alloys are susceptible to a stable cracking process called delayed hydride cracking (DHC). DHC has two stages: (a) crack initiation that requires a minimum crack driving force (the threshold stress intensity factor, KIH) and (b) stable crack growth that is weakly dependent onKl,. The value of KIH is an important element in determining the tolerance of components to sharp flaws. The rate of cracking is used in estimating the action time for detecting propagating cracks before they become unstable. Hence, it is important for reactor operators to know how these properties change during service in reactors where the components are exposed to neutron irradiation at elevated temperatures. DHC properties were measured on a number of components, made from the two-phase alloy Zr-2.5Nb, irradiated at temperatures in the range of 250 to 290°C in fast neutron fluxes (E ≥ 1 MeV) between 1.6 × 1017 and 1.8 × 1018 n/m2 ∙ s to fluences between 0.01 × 1025 and 9.8 × 1025 n/m2. The neutron irradiation reduced KIH by about 20% and increased the velocity of cracking by a factor of about five. The increase in crack velocity was greatest with the lowest irradiation temperature. These changes in the crack velocity by neutron irradiation are explained in terms of the combined effects of irradiation hardening associated with increased -type dislocation density, and β-phase decomposition. While the former process increases crack velocity, the latter process decreases it. The combined contribution is controlled by the irradiation temperature. X-ray diffraction analyses showed that the degree of β-phase decomposition was highest with an irradiation temperature of 290°C while -type dislocation densities were highest with an irradiation temperature of 250°C.
Correlation Between Irradiated and Unirradiated Fracture Toughness of Zr-2.5Nb Pressure Tubes
Authors: Davies PH , Hosbons RR , Griffiths M , Chow CK
Published: March 2009

Three coordinated research programs were undertaken on the fracture toughness of Zr-2.5Nb pressure tubes to determine relationships between irradiated and unirradiated values, the effect of long-term irradiation, and the causes of the variation in toughness. The present paper describes results from these programs and their implications.

It is shown that a correlation exists between the toughness of the pressure tube material before and after irradiation to a fast-neutron fluence of 1 × 1026 n ∙ m-2 (E > 1 MeV). Further, for the majority of tubes, degradation occurs early in the lifetime of a CANDU reactor; that is, at fluences <2 × 1024 n ∙ m-2. Limited results on relatively low-toughness materials indicate that the flux does not have a major effect on the irradiated toughness and that saturation is complete by about 1.6 × 1025 n ̇ m-2.

The results are discussed in the light of detailed fractographic and microstructural (X-ray diffraction, transmission electron microscopy) studies carried out on the irradiated and unirradiated pressure tube material. It is shown that in the presence of void nucleating sites, such as microsegregated species (chlorine and carbide) and particles (phosphides and carbides), very large reductions in toughness occur with irradiation. In the absence of such species, there is little deterioration in toughness, and the high crack-tip strains (toughness) achieved with unirradiated material can be maintained after irradiation.
On the Anisotropy of In-Reactor Creep of Zr-2.5Nb Tubes
Authors: Causey AR , Elder JE , Holt RA , Fleck RG
Published: March 2009

Creep specimens made from cold-worked Zr-2.5Nb tubes, fabricated with two different microstructures and crystallographic textures, were irradiated in the Osiris reactor in France in a fast neutron flux of about 1.8 × 1018 n ∙ m-2 ∙ s-1, E > 1 MeV, at 553 and 585 K. The hoop stresses from internal pressurization range from 0 to 160 MPa. The basal poles were oriented in the radial-transverse plane of the tubes, either about 30° from the radial direction or primarily in the transverse direction; these are similar to the crystallographic textures in fuel sheathing and in CANDU reactor pressure tubes. Dislocation densities were similar while grain size and shape differ significantly.

The creep specimens were irradiated to fast neutron faiences up to 7 × 1025 n ∙ m-2. Creep rates were obtained from strain versus fluence plots and creep compliances were obtained from plots of the strain rates against hoop stress for each material at each temperature. The ratio of creep rates at the nominal temperature of 583 K to those at 553 K was similar to that derived from stress relaxation results at temperatures between 523 and 568 K.

The ratio of the biaxial creep compliance in the axial direction to that in the transverse directions is different for the two test materials; 0.0 to -0.1 for the fuel sheathing texture and 0.6 to 0.7 for the pressure tube texture. The results were analyzed using a self-consistent model developed previously to account for the contributions to the creep anisotropy of the three microstructure parameters involved here and for the grain interaction effects. The model, which was normalized to other test reactor and power reactor creep data for cold-worked Zr-2.5Nb tubes, predicted the ratio of the creep compliances to be -0.26 and 0.63, respectively. Thus, in agreement with previous conclusions, the creep anisotropy of Zr-2.5Nb tubes with pressure-tube-like crystallographic texture can be adequately predicted.
Modeling of Damage in Cold Pilgering
Authors: Aubin JL , Girard E , Montmitonnet P
Published: March 2009

Surface defects may occur in cold pilgering of Zircaloy-4 tubes caused by the stress and strain history. Because the low frequency of these defects makes their direct study difficult, a model has been built to describe the mechanical conditions that prevail during the pass, as a function of tool design, rolling parameters, and friction. It is based upon the geometrical definition of strains that is transformed into stresses via the Von Mises plastic flow rule and a slab method. Rolling forces are deduced and compared with experiments, and the damage function is computed. A number of experimental observations has been performed (axial movements of tube and mandrel, bulge wave propagation, contact length, shearing strains, etc.) that provides the correct hypotheses for the model. A correlation is established between the computed damage function and the frequency and severity of the studied defects.
Fabrication Process of High Nodular Corrosion-Resistant Zircaloy-2 Tubing
Authors: Abe H , Matsuda K , Hama T , Konishi T , Furugen M
Published: March 2009

A new fabrication process of high nodular corrosion-resistant Zircaloy-2 tubing for boiling water reactors (BWRs) water rods has been developed. The main features and findings are: 1. Development of a new quenching machine and method, by which tube shell can be α + β through-wall quenched at a rapid cooling rate of >50 K/s from 1173 to 1073 K. 2. High nodular corrosion-resistant tube shells, quenched at both hollow billet and tube shell stages, have less deformability, especially in the circumferential compression direction. 3. Reduction in area in combination with Q-value affect crack sensitivity during pilgering. Area reductions greater than 80% at high Q-values were proved possible with minimal or no cracking. 4. Consequently, a new fabrication process, consisting of two cold reduction passes from tube shell to final product, has been successfully developed. The final tubing showed high nodular corrosion resistance, having no nodules in the high temperature (773 K) corrosion test.
Aqueous Chemistry of Lithium Hydroxide and Boric Acid and Corrosion of Zircaloy-4 and Zr-2.5Nb Alloys
Authors: Ramasubramanian N , Balakrishnan PV
Published: March 2009

The chemistry of the aqueous solution, surface chemistry of zirconium oxide (ZrO2), and the physical structure of the corrosion film have to be considered for an understanding of the mechanism of corrosion of zirconium alloys in aqueous solutions. Based on information available in all these areas, we are proposing a model for oxide growth on Zircaloy-4 fuel cladding and Zr-2.5Nb pressure tube material, in lithium hydroxide (LiOH) solutions with and without added boric acid (H3BO3).

Corrosion exposures were at 360°C and were short term of four-day duration. Concentration of lithium covered the range 0.7 to 3500 ppm and boron was added at 300, 600 and 1200 ppm. Weight gain, Fourier Transform InfraRed (FTIR) spectroscopy, and Secondary Ion Mass Spectrometry (SIMS) were used to characterize the oxide films. Potentiodynamic polarization measurements were made in separate tests at 315°C. The chemistry of LiOH-H3BO3 system at 300 to 360°C was evaluated from the ionization constants of water, LiOH, and H3BO3.

There is no simple relationship between pH and corrosion. In the absence of boron acceleration in corrosion, in these short-term tests, is observed at concentrations >350 ppm Li for Zircaloy 4 and at >60 ppm Li for Zr-2.5Nb. This is attributed to the modification of normal oxide growth by surface OLi groups formed by reaction with undissociated LiOH in the solutions. In the case of Zircaloy-4, the inhibition of accelerated corrosion by H3BO3 is greater than what can be accounted for by its neutralizing action on LiOH. The mechanism suggested is the removal of surface OLi groups by reaction with non-ionized H3BO3. Boric acid at high concentrations has a detrimental effect on the accelerated corrosion of Zr-2.5Nb alloy.

According to the model proposed for oxide growth, the corrosion behavior can be classified into two categories: (1) growth of post-transition type films under acceleration conditions where solution had access into the oxide and (2) growth of pre-transition films under non-acceleration conditions where the solution had not gained access into the oxide. For Case 1, the pores have to be >2 nm in diameter so that interfacial double layer requirements are met for solution incursion in the oxide and the unleachable lithium and boron on the surfaces of oxide grains are from ion exchange and reactions with LiOH and H3BO3. In Case 2, the outer surfaces of oxide grains, which were exposed to the solution, have lithium and boron similar to that described for Case 1. The lithium and boron in the bulk of these pre-transition films are ascribed to LiOH and H3BO3 hydrogen-bonded to water and adsorbed on the surfaces of oxide grains.
Irradiation Effect on Fatigue Behavior of Zircaloy-4 Cladding Tubes
Authors: Soniak A , Lansiart S , Royer J , Mardon J-P , Waeckel N
Published: March 2009

Since nuclear electricity has a predominant share in French generating capacity, pressurized water reactors (PWRs) are required to fit grid load following and frequency control operating conditions. Consequently, cyclic stresses appear in the fuel element cladding. In order to characterize the possible resulting clad damage, fatigue tests were performed at 350°C on unirradiated material or irradiated stress relieved Zircaloy-4 tube portions, using a special device for tube fatigue by repeated pressurization.

It appears that, for high stress levels, the material fatigue life is not affected by irradiation. But the endurance fatigue limit undergoes a decrease from the 350 MPa value for unirradiated material to the 210 MPa value for the material irradiated for four cycles in a PWR. However, this effect seems to saturate with irradiation dose: no difference could be detected between the two cycles' results and the corresponding four cycles' results. The corrosion effect and the load following influence were also investigated: they do not appear to modify the fatigue behavior in our experimental conditions.
Microstructure of Oxide Layers Formed During Autoclave Testing of Zirconium Alloys
Authors: Wadman B , Lai Z , Andrén H-O , Nyström A-L , Rudling P , Pettersson H
Published: March 2009

The microstructure of oxide layers formed in steam in a 400°C, 10.3-MPa autoclave on different zirconium alloys was studied by transmission electron microscopy. Pre-and post-transition oxide layers on Zircaloy-4 with different heat treatments, and post-transition oxide layers on Zr-0.5Sn-0.53Nb were compared. Special attention was paid to the oxide-metal interface. In Zircaloy-4 with short annealing times and high post-transition corrosion rates, the interface had a disordered structure, and pores were found in the oxide very close to the interface. In Zircaloy-4 with low uniform corrosion rates, the interface consisted of highly ordered, columnar grains. The interface in Zr-0.5Sn-0.53Nb had a different appearance, with an intermediate phase of equiaxed grains between the columnar oxide and the metal. The hydrogen absorption of the zirconium alloys during oxidation was measured by the melt extraction technique on samples oxidized for 63, 147, and 343 days. The Zr-0.5Sn0.53Nb alloy had considerably lower hydrogen absorption than Zircaloy-4.
Corrosion Optimized Zircaloy for Boiling Water Reactor (BWR) Fuel Elements
Authors: Garzarolli F , Schumann R , Steinberg E
Published: March 2009

A corrosion optimized Zircaloy has to be based primarily on in-boiling water reactor (in-BWR) results. Therefore, the material parameters affecting corrosion were deduced from results of experimental fuel rod irradiation with systematic variations and from a large variety of material coupons exposed in water rods up to four cycles.

The major material effect is the size and distribution of precipitates. For optimizing both early and late corrosion, the size has to stay in a small range. In the case of material quenched in the final stage, the quenching rate appears to be an important parameter. As far as material chemistry is concerned, the in-BWR results indicate that corrosion in BWRs is influenced by the alloying elements tin, chromium, and the impurity silicon.

In addition to corrosion optimization, hydriding is also considered. A large variation from lot to lot under identical coolant condition has been found. The available data indicate that the chromium content is the most important material parameter for hydrogen pickup.
In-Reactor Corrosion Performance of ZIRLO™ and Zircaloy-4
Authors: Sabol GP , Comstock RJ , Weiner RA , Larouere P , Stanutz RN
Published: March 2009

In-reactor and long-term autoclave corrosion data have been obtained on ZIRLO and three variants of Zircaloy-4: conventional (1.5% tin), low-tin, and beta-treated. In-reactor data from demonstration assemblies irradiated in the Virginia Power Company's North Anna Unit 1 reactor demonstrate the superiority of ZIRLO and, to a lesser extent, low-tin Zircaloy-4 over conventional Zircaloy-4. After two cycles of irradiation to an assembly burnup of 37.8 GWD/MTU, the average axial peak corrosion of ZIRLO was 32% that of conventional Zircaloy-4. Low-tin and beta-treated materials displayed average peak oxides 76% and 150% of that formed on conventional Zircaloy-4, respectively.

Autoclave corrosion tests of archive tubing have been performed in 633 K water, 672 K, 700 K, and 727 K steam, and in 633 K water containing 70 and 210 ppm lithium as the hydroxide. Correlation of the in-reactor data with the autoclave data indicates that the 633 K pure water test is the best qualitative indicator of in-reactor corrosion performance, and the 672 K steam test the poorest. Differences in in-reactor corrosion between ZIRLO and the Zircaloy-4 materials are consistent with the relative behavior of these materials in lithium hydroxide solutions. The relationships among the in-reactor and autoclave corrosion data, the microstructures, and the processing are discussed.

In addition to improved corrosion resistance, ZIRLO exhibits improved dimensional stability over Zircaloy-4. The in-reactor creep of ZIRLO is confirmed to be about 80% of that of Zircaloy-4, and irradiation growth is observed to be about 50% that of Zircaloy-4. These data are also presented and discussed.
International Civil Aviation Organization (ICAO) and Its Aviation Security Program
Authors: Stohr E
Published: March 2009

A review is undertaken of International Civil Aviation Organization (ICAO) activities in response to unlawful interference, including a historical background and trends in the types of activities that terrorists have taken against civil aviation. ICAO, as a result of a meeting of the Ministers of Transportation from around the world meeting as Council Representatives on 16 Feb. 1989, set the pattern for future activities. This presentation will outline the new ICAO organization to address security matters in civil aviation.
Vapor Detection of Explosives
Authors: Fine DH , Achter EK
Published: March 2009

The science of explosives vapor detection is reviewed. A variety of physical mechanisms are available for transport of explosives molecules from a hidden explosive device to a detector. The importance of sampling techniques and detector selectivity is emphasized.
Thermomechanical Cyclic Deformation of Metal-Matrix Composites
Authors: Karayaka M , Sehitoglu H
Published: March 2009

A constitutive model is developed for unreinforced Al2xxx-T4 and silicon-carbide particulate (SiCp) reinforced Al2xxx-T4. Its capabilities are also outlined for predicting the cyclic, isothermal, and thermomechanical behaviors of the composite and its constituents. The constitutive model for unreinforced Al2xxx-T4 is also a unified model, because it combines creep and plastic strains as inelastic strains. The unified model for the matrix is combined with Eshelby's equivalent inclusion theory, which is modified to handle finite volume fraction and inelastic deformation, to simulate the behavior of the reinforced material. The behavior of Al2xxx-T4 (reinforced with 20% volume fraction of SiCp) was simulated at temperatures ranging from 20 to 300°C and strain rates of 3.10-5 1/s to 3.10-3 1/s. The model predicts the strengthening of the composite relative to the unreinforced matrix for isothermal and thermomechanical loading conditions.

The internal stress-strain behavior of the constituents (volumetric average) is reported. It is demonstrated that the matrix and the particulates experience a multiaxial stress state under uniaxial loading of the composite. The coefficient of thermal expansion mismatch between the reinforcement and the matrix contributes further to the multiaxial stress state. When the mechanical strain and temperature are in-phase, the transverse stress component in the matrix is out-of-phase with the longitudinal stress component. When the temperature and mechanical strain are out-of-phase, the transverse and longitudinal stress components are in-phase. The results on internal stress-strain fields provide insight into the interpretation of fatigue behavior of particle-reinforced composites at elevated temperatures.
Mechanical Properties of Amorphous and Roll-Drawn Polypropylene
Authors: McCammond D , Sinclair AN , Sinclair LA
Published: March 2009

Mechanical properties of both amorphous polypropylene and roll-drawn polypropylene sheet are examined using four experimental techniques: creep, transverse vibrating cantilever beam, axially resonating rod, and ultrasonic time-of-flight. Variations of the principal dynamic moduli were determined over 14 decades of frequency, at a single temperature. The ultrasonic time-of-flight technique yielded the dynamic and shear moduli at 5 MHz for all three principal axes of the roll-drawn sheet; the results indicated the material to be transversely isotropic. The three-dimensional stiffness matrix was populated at 5 MHz; its two-dimensional counterpart was then compared to the 0.01 Hz stiffness matrix of Sinclair and McCammond.
The Influence of Constituent Properties on the Compression Behavior of Laminates with Discontinuities
Authors: Crane DL , Bradley WL , Barron DL
Published: March 2009

This study addresses the compressive behavior of graphite fiber reinforced composites containing open holes and impact damage. The effect of constituent properties as well as thermoplastic and rubber particulate toughening mechanisms are evaluated. The materials are characterized by their neat resin elongation to failure, elastic properties, ultimate strengths, fiber/matrix interfacial shear strength, and Modes I and II interlaminar fracture toughness. The open-hole and post-impact compression properties of the materials have also been evaluated. Results indicate that an increase in the in-plane lamina shear modulus results in an increase in the strain associated with the initiation of fiber microbuckling in notches. Also, an increase in neat resin elongation to failure and Modes I and II fracture toughness reduces the total volume of material subject to damage as a result of impact. Less damage in the laminate leads to increases in the post-impact compression properties.
Split Spectrum Processing of Backscattered Rayleigh Wave Signals to Improve Detectability of Fatigue Microcracks
Authors: Resch MT , Karpur P
Published: March 2009

A surface acoustic wave nondestructive evaluation technique was used to detect the initiation of surface microcracks in highly stressed regions of hourglass shaped 2024-T6 alloy aluminum specimens during fatigue cycling. Contacting wedge transducers were used to excite the incident waves and to detect the reflected wave signals. The effectiveness of a split spectrum processing algorithm to separate specular reflections of isolated cracks from nonspecular reflections of microstructural features in the scattering field was demonstrated.
The Application of Dynamic Mechanical Methods to T
g Determination in Polymers: An Overview
Authors: Chartoff RP , Weissman PT , Sircar A
Published: March 2009

Many factors are involved with establishing Tg values from Dynamic Mechanical Methods. These can be grouped as: (a) instrumental factors (b) test frequency (c) material characteristics (d) choice of Tg criterion Instrumental factors may include temperature calibration, thermal gradients, sample size, clamping effects, and sample geometry. Increasing test frequency causes a shift of Tg to higher temperatures. Material characteristics include such factors as the degree of crystallinity in crystalline polymers, the degree of crosslinking in thermosets, the specific thermal and mechanical history of the material, and possible moisture effects. The Tg criterion selected relates to the subjective choice of viscoelastic function used to establish Tg. For example, the peak value of E" will give a different result than the peak tanδ.

In this paper we will review these various aspects of determining Tg, citing examples in each category which illustrate problems in assigning appropriate Tg values.