bluuebunny/crossref_metadata_2025 huggingface dataset:
A Continued Evaluation of the Role of Material Hardening Behavior for the NeT TG1 and TG4 Specimens
Authors: Dewees David J. , Prueter Phillip E. , Kummari Seetha Ramudu
Published: November 2014

Modeling of cyclic elastic-plastic material behavior (hardening) has been widely identified as a critical factor in the finite element (FE) simulation of weld residual stresses. The European Network on Neutron Techniques Standardization for Structural Integrity (NeT) Project has provided in recent years both standard test cases for simulation and measurement, as well as comprehensive material characterization. This has allowed the role of hardening in simulation predictions to be isolated and critically evaluated as never before possible. The material testing information is reviewed, and isotropic, nonlinear kinematic and combined hardening models are formulated and tested. Particular emphasis is placed on material model selection for general fitness-for-service assessments, as it relates to the guidance for weld residual stress (WRS) in flaw assessments of in-service equipment in Annex E of the FFS standard, API 579-1/ASME FFS-1.
Design and Analysis of Brick Lined Autoclaves for the Mining Industry
Authors: Stefanovic Radoslav , Tucker Paul , Miller George , Messer Barry , Doctor Christopher
Published: November 2014

This paper focuses on design optimization of brick-lined autoclaves to reduce wall thickness without compromising autoclave integrity. The use of acid resistant, brick lined, horizontal, autoclaves is common for hydrometallurgical processing within the mining industry. To prevent corrosion of the carbon steel pressure boundary, autoclaves are often lined with an acid proof flexible membrane and high nickel alloy overlay localized at nozzle areas. A brick lining protects the membrane against high temperature and abrasive damage that would result in corrosion of the carbon steel pressure boundary. Because of stringent out-of-roundness and deflection requirements, autoclave designers are faced with the challenge of choosing the proper thickness and layout of the autoclaves. Common practice for satisfying stringent requirements is to design much thicker autoclave than what is required to satisfy pressure and temperature conditions. This paper provides a methodology for the design that utilizes stiffening rings for controlling out-of-roundness that results in thinner and lighter autoclaves.
The Effect of Upstream Edge Geometry on the Acoustic Resonance Excitation in Shallow Rectangular Cavities
Authors: Omer Ahmed , Arafa Nadim , Mohany Atef , Hassan Marwan
Published: November 2014

The flow-excited acoustic resonance phenomenon is created when the flow instability oscillations are coupled with one of the acoustic modes, which in turn generates acute noise problems and/or excessive vibrations. In this study, the effect of the upstream edge geometry on attenuating these undesirable effects is investigated experimentally for flows over shallow rectangular cavity with two different aspect ratios of L/D = 1 and 1.67, where L is the cavity length and D is the cavity depth, and for Mach number less than 0.5. The acoustic resonance modes of the cavity are self-excited. Twenty four different upstream cavity edges are investigated in this study; including round edges, chamfered edges, vortex generators and spoilers with different sizes and configurations. The acoustic pressure is measured with a flush-mounted microphone on the cavity floor and the velocity fluctuation of the separated shear layer before the onset of acoustic resonance is measured with a hot-wire probe. The results for each upstream cavity edge are compared with the base case when square cavity edge is used. It is observed that when chamfered edges are used, the amplitude of the first acoustic resonance mode is highly intensified with values reaching around 5000 Pa (compared to 2000 Pa for the base case) and a clear shift in its onset of resonance to higher flow velocities is observed. Similar trend is observed when round edges are used. The amplitude of the generated pressure of the first acoustic resonance mode is amplified with values exceeding 4000 Pa and a delay in its onset of acoustic resonance is observed as well. Most of the spoiler edges are found to be effective in suppressing the pressure amplitude of the excited acoustic resonance. However, the performance of each spoiler depends on its specific geometry (i.e. thickness, height, and angle) relative to the cavity aspect ratio. A summary of the results is presented in this paper.
Uncertainty Characterization of Engineering Failure Data
Authors: Wei Zhigang , Nikbin Kamran
Published: November 2014

How to quantitatively measure the uncertainty of engineering failure data is an important but still unsolved task in probabilistic risk analysis. This paper aims to fill the gap first by specifying the requirements for a robust uncertainty measure to meet the criteria. Complexity and uncertainty measurements in computational complexity, classical statistical mechanics and information theory are also reviewed for possible inspiration. In this paper, a new groundbreaking parameter, which is related to reliability or survival function, is selected to characterize the uncertainty of engineering failure data with given probabilistic distributions. The uncertainty formulae based on the Shannon entropy and the new uncertainty parameter for various distribution functions are also provided. Finally, several examples are given to demonstrate the applicability of the new uncertainty measure in durability and reliability analyses.
Development of the RCC-MR Creep Deformation Model for the Prediction of Creep and Stress Relaxation in Type 321 Stainless Steel
Authors: Moffat A. J. , Douglas J. P. , White M. , Spindler M. W. , Austin C. , Jacques S.
Published: November 2014

In this paper a creep deformation model has been developed for Type 321 stainless steel which has been based on a modified version of the creep model that is used in the French fast reactor design code RCC-MR.

The model has been evaluated using: 1) constant load creep data covering the temperature range from 550°C to 650°C and 2) constant displacement, stress relaxation data obtained from creep-fatigue tests at 650°C. Samples in the heat-treatment conditions of solution-treated, aged, and simulated ‘heat affected zone’ have been assessed.

The standard RCC-MR model was fitted to the constant load data and provided good predictions of forward creep. However, when this model was used to predict stress relaxation it was observed that the model significantly over predicted creep strain rates and therefore the level of stress drop during each cycle.

During constant load tests the stress remains relatively constant (noting that true stress does increase a small amount prior to rupture). However, in relaxation tests the stress varies significantly over the dwell. Due to the poor predictions of stress relaxation it was hypothesised that the fitted model did not capture the stress dependence of creep appropriately. The RCC-MR model was therefore modified to include a primary and secondary threshold stress term that is a function of the accumulated creep strain.

This work indicates that the RCC-MR model, modified to include threshold stresses, can be used to provide good predictions of both forward creep and stress relaxation in Type 321 stainless steel. Further work is required to validate this model on stress relaxation data at additional temperatures and lower start of dwell stresses.
Physical and Numerical Methods for the Dynamic Behavior of the Fast Reactor Cores
Authors: Broc Daniel , Cardolaccia Jérome , Martin Laurent
Published: November 2014

In the frame of the GEN IV Forum and of the ASTRID Project, a program is in progress in the CEA (France) for the development and the validation of numerical tools for the simulation of the dynamic mechanical behavior of the Fast Reactor cores, with both experimental and numerical parts.

The cores are constituted of Fuel Assemblies (of FA) and Neutronic Shields (or NS) immersed in the primary coolant (sodium), which circulates inside the Fluid Assemblies. The FA and the NS are slender structures, which may be considered as beams, form a mechanical point of view. The dynamic behavior of this system has to be understood, for design and safety studies. Two main movements have to be considered: global horizontal movements under a seismic excitation, and opening of the core. The dynamic behavior of the core is strongly influenced by contacts between the beams and by the sodium. The contacts between the beams limit the relative displacements. The fluid leads to complex interactions between the structures in the whole core.

The paper presents the physical and numerical methods and tools used to describe and simulate the phenomena. A key point is the Fluid Structure Interaction (or FSI): the interactions between the beams and the liquid sodium. The fluid movement is assumed to be described by the equations of a perfect fluid. Simple and efficient homogenization methods may be used to reduce the size of the problem. These methods are integrated in a general computer code, CAST3M developed at the CEA Saclay. This computer code allows to take into account the impacts between the beams. Some applications are presented.
Fracture Toughness Assessment of SA508 Gr 3 Steel for KSNP RPV Using Conventional and Bimodal Master Curve Approaches
Authors: Kim Jongmin , Kim Minchul , Choi Kwonjae , Lee Bongsang
Published: November 2014

The standard master curve approach has the major limitation, which is only applicable to homogeneous datasets. In nature, steels are macroscopically inhomogeneous and thus the fracture toughness has larger scatters than expected by a conventional master curve approach. RPV steel has different fracture toughness with varying distance from the inner surface of the wall. Regarding this, a clear tendency was reported in that the toughness extracted near the surface had to be higher than in the center region due to the higher quenching rate at the surface (deterministic material inhomogeneity). On the other hand, the T0 value itself behaves like a random parameter when the datasets have a large scatter due to the datasets consisting of several different materials such as welding region (random inhomogeneity). In the present paper, four regions, the surface, 1/8T, 1/4T and 1/2T, were considered for fracture toughness specimens of KSNP (Korean Standard Nuclear Plant) SA508 Gr. 3 steel to provide deterministic material inhomogeneity and random inhomogeneity effect. Specimens were extracted from these four regions and fracture toughness tests were performed at various temperatures in the transition region. Several concepts were provided for the master curve of inhomogeneous materials such as a bimodal and random inhomogeneous master curve scheme, and among them, the bimodal master curve analyses were reviewed and compared with a conventional master curve approach to find the random inhomogeneity. The bimodal master curve considering inhomogeneous materials provides better description of scatter in fracture toughness data than conventional master curve analysis, but it is unclear to provide evidence that the bimodal analysis lines follow the data more closely than the conventional master curve analysis.
Flow-Induced Transverse Vibration of a Cantilevered Prism for Energy Harvesting
Authors: Kiwata Takahiro , Yamaguchi Makoto , Nakajima Aguri , Kono Takaaki , Ueno Toshiyuki
Published: November 2014

Various types of hydroelectric power generators have been developed, and small-scale hydroelectric power generation is expected to provide an independent, dispersed power supply for harnessing hydro-energy of small-sized rivers and agricultural waterways. In order to investigate the effects of the geometric shape of a bluff body’s cross section on the flow-induced transverse-galloping vibration, we performed free-vibration tests of a cantilevered prism with three kinds of cross sections, i.e., rectangular, D-section, and triangular prisms. The effects of the side ratio D/H (where D: depth of a bluff body in the flow direction, H: height of a bluff body normal to the flow direction) and the turbulence intensity of the free stream on the flow-induced vibration were also investigated. It was found that the vibrations of the thin rectangular, D-section, and triangular prisms occur at lower reduced velocity than that of the thick prisms. We also carried out a power-generation experiment using iron-gallium alloy that is a kind of magnetostrictive material to investigate a possibility of harvesting energy from the transverse-galloping vibration in a water flow. The energy harvester using magnetostrictive material and a rectangular prism with D/H = 0.2 generated a maximum electric power of 0.35 W at a reduced velocity of Vr = 4.4.
An Assessment of Mechanical Properties of A508-3 Steel Used in Chinese Nuclear Reactor Vessels
Authors: Yu Meifang , Luo Zhen , Chao Y. J.
Published: November 2014

China has very ambitious goals of expanding its commercial nuclear power by 30 Giga-Watts within the decade and wishes to phase out fossil fuels emissions by 40–45% by 2020 (from 2005 levels). With over 50 new nuclear power plants under construction or planned and a design life of 60 years, any discussions on structural integrity become very timely. Although China adopted its nuclear technology from France or US at present time, e.g. AP1000 of Westinghouse, the construction materials are primarily “Made in China”. Among all issues, both the accumulation of the knowledge base of the materials and structures used for the power plant and the technical capability of engineering personnel are imminent. This paper attempts to compile and assess the mechanical properties, Charpy V-notch impact energy, and fracture toughness of A508-3 steel used in Chinese nuclear reactor vessels. All data are collected from open literature and by no means complete. However, it provides a glimpse into how this domestically produced steel compares with western reactor vessel steels such as US A533B and Euro 20MnMoNi55.
ANDE-1: An ASME Nondestructive Examination and Quality Control Qualification and Certification National Standard
Authors: Turnbow Michael L.
Published: November 2014

The American Society for Mechanical Engineers (ASME) is developing and implementing a Nondestructive Examination (NDE) and Quality Control (QC) personnel qualification and certification program (ANDE). In keeping with ASME development of codes and standards the NDE program will be assembled by industry experts and administered centrally by ASME. A new ASME standard recognized by ANSI is being developed as the core of the program and will be based upon industry best practices. The total program is a significant paradigm change from the traditional employer based and other central qualification and certification programs, the new standard will include features such as the Systematic Approach to Training, Job Task Analysis and Qualification Cards to direct the development of training and experience. The program was designed to improve the skill level and consistency amongst NDE practitioners and will use the performance-based approach including psychometric practices in the development of both written and practical demonstration examinations. This paper will primarily focus on the development of the standard and its salient features.
Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities: Part 4 — Failure Behavior of Crossover Piping for Seismic Isolation System
Authors: Otoyo Teruyoshi , Otani Akihito , Fukushima Shunsuke , Jimbo Masakazu , Yamamoto Tomofumi , Sakakida Takaaki , Onishi Shigenobu
Published: November 2014

This paper provides a part of the series titled “Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities”. This part shows the failure behavior of crossover piping installed in a seismic isolated plant. The considered crossover piping is supported on one side by an isolated building and by a non-isolated building on the other side. During an earthquake, the piping structure is deformed due to the large relative displacements between the two buildings and at the same time excited by the different building seismic responses. Therefore, the high-pressure crossover piping structure requires both flexibility and strength.

In this study, 1/10 scaled shaking tests and FEM analyses have been performed to investigate the failure behavior of the crossover piping, where both seismic motions and excitations have been taken into account. It was confirmed that the failure occurs at the piping elbow through low cycle fatigue. Moreover, the results of the elastic-plastic response analysis, which simulates an extreme level of excitation corresponding to more than three times the design level, are in good agreement with the test results. The simulation also succeeded in predicting the experimental failure location.
Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities: Part 3 — Seismic Response of Crossover Piping for Seismic Isolation System
Authors: Otani Akihito , Otoyo Teruyoshi , Hirai Hideo , Iiizumi Hirohide , Shimizu Hiroshi , Saitoh Mitsuru , Onishi Shigenobu
Published: November 2014

This paper, which is part of the series entitled “Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities”, shows the linear seismic response of crossover piping installed in a seismically isolated plant. The crossover piping, supported by both isolated and non-isolated buildings, deforms with large relative displacement between the two buildings and the seismic response of the crossover piping is caused by two different seismic excitations from the buildings. A flexible and robust structure is needed for the high-pressure crossover piping.

In this study, shaking tests on a 1/10 scale piping model and FEM analyses were performed to investigate the seismic response of the crossover piping which was excited and deformed by two different seismic motions under isolated and non-isolated conditions. Specifically, as linear response analysis of the crossover piping, modal time-history analysis and response spectrum analysis with multiple excitations were carried out and the applicability of the analyses was confirmed. Moreover, the seismic response of actual crossover piping was estimated and the feasibility was evaluated.
Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities: Part 5 — Fatigue Test of the Crossover Piping
Authors: Mizuno Kotoyo , Shimizu Hiroshi , Jimbo Masakazu , Oritani Naohiko , Onishi Shigenobu
Published: November 2014

This paper provides a part of the series of “Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities”.

It is assumed the main steam crossover piping is damaged by the ratcheting deformation based on the relative displacement and the inertia load by the earthquake between the buildings and the internal pressure.

This part shows a low cycle ratcheting fatigue test using the scaling model under the combined loadings based on the relative displacement and the inertia load by the earthquake between the buildings and analyses were performed to confirm the failure modes and the fatigue life of the pipe elbow for the fatigue damage of the long-period ground motion.

As a result, the fatigue life under combined loads was sufficiently higher than the design criteria and analyses are good match with the test results. So, it confirmed the structural integrity of the crossover piping.
Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities: Part 1 — The Work Schedule of Project and a Seismic Design of Crossover Piping System
Authors: Suzuki Yutaka , Sato Kunihiko , Iiizumi Hirohide , Hisatsune Masakazu , Onishi Shigenobu
Published: November 2014

This paper provides a part of series of “Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities” [1]–[4]. This part describes the work schedule of this project and the summary of a seismic design for crossover piping system.

Since the Southern Hyogo Prefecture Earthquake in 1995, a seismic isolated design has been widely adopted for Japanese typical buildings. The Japanese government accepted utilizing seismic isolation technology for nuclear power facilities with the 2006 revision of the “Regulatory Guide for Reviewing Seismic Design of Nuclear Power Reactor Facilities”. Under these backgrounds, the Japan national project with the participation of all electric power companies and reactor vendors has been started from 2008 to develop seismic isolation systems of nuclear power facilities under the support of the Ministry of Economy, Trade and Industry.

In the design of seismic isolated plant, the crossover piping systems, such as Main Steam line and other lines related to the safety system have the important roles for overall plant safety. Therefore, the design of multiply supported piping systems between isolated and non-isolated buildings is one of the major key issues.

This paper focuses on the seismic response analysis of Main Steam crossover piping between seismic isolated Reactor Building and non-isolated Turbine Building. Multiple input response spectra and time history analyses of the crossover piping have been performed and the structural integrity of piping and the validity of the multiple input analysis method have been verified based on comparisons with the results obtained by conventional response spectrum analysis using enveloped floor response spectrum.
Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities: Part 10 — Evaluation of Seismic Isolator Design
Authors: Asano Hiroyuki , Hirotani Tsutomu , Nakayama Takashi , Norimono Takemi , Aikawa Yuji , Sato Kunihiko , Asakura Shinji , Jimbo Masakazu , Umeki Yoshito
Published: November 2014

This paper provides a part of series of “Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities”. This part shows an evaluation of seismic isolator design established in this project where several methods are newly developed. The major four accomplishments are as follows.

One: establishment of design earthquake specially considered for seismically isolated nuclear power facilities. The design earthquakes are made to fit multiple target spectra with different damping factors considering a building, equipment and seismic isolators for more precise response analyses.

Two: design and development of a high-performance seismic isolator. Against the large design earthquakes, a seismic isolator is newly developed which has a large diameter lead plug for more damping; the isolators were actually manufactured and tested.

Three: seismic response analyses for seismically isolated nuclear power plants. Light water reactors are designed where the structural characteristics of the seismic isolation system is reflected.

Four: evaluation of thermal effects on seismic isolators by a long-duration earthquake. Considering a long-duration earthquake, the heat generation phenomenon in the lead plug is analytically evaluated to ensure the lead plug’s damping performance.

By introducing these accomplishments, the realistic design of a seismically isolated nuclear power plant is achieved.
Study on Stability Analysis on Acoustic Resonance in Heat Exchanger Tube Bundles
Authors: Nishida Eiichi , Hamakawa Hiromitsu
Published: November 2014

Acoustic resonance may occur in heat exchangers such as gas heaters or boilers which contain tube bundles. This resonance is classified in self-excited oscillation, and feedback effect between vortex shedding and sound field plays important role. The final goal of our study is to develop a method by which to predict the resonance attack critical gas flow velocity and maximum resonance amplitude at the design stage. In order to reach this goal, it is essential to formulate the feedback effect between vortex shedding and a resonance mode concerned, and to execute a stability analysis of the resonance mode. There are two mechanisms in the feedback process: as the acoustic resonance grows, vortex strength is increased and vortex shedding synchronization grows.

This paper is concerned with the proposal of phenomenological model suitable to explain this mechanism and the formulation of these kinds of feedback mechanism with the use of this model. The model adopts vortex shedding wake oscillator model which is effective for tube vibration problems. Tube vibration movement is replaced by acoustic particle movement. Another improvement of our study is the introduction of statistical modeling of the wake oscillator to express vortex shedding synchronization effect. Here, the randomness of vortex shedding is explicitly modeled by a probability density function of the phase of the oscillator, and this function depends on the level of acoustic resonance. Based on these ideas to express the vortex/acoustics interaction, the formulas of stability analysis were derived.
Revision of Flaw Evaluation Methods of Pipes Having a Circumferential Flaw in JSME Fitness-for-Service Codes
Authors: Machida Hideo , Itatani Masao , Kamaya Masayuki
Published: November 2014

This paper shows the technical basis of revision to the JSME Fitness-for-Service Code (the FFS code) for flaw evaluation methods of pipes which have a very shallow circumferential flaw. When a flaw in a pipe is very small, the allowable stress between the FFS code and the JSME Design and Construction Code (the design code) is mismatched. Fracture strength of a pipe with small flaw depends on the tensile strength accompanied by large deformation. Therefore, fracture mechanics is not applicable in such a case. This mismatch has been resolved for an axial crack assessment by improving definition of flow stress for shallow crack. In this study, the authors investigated this mismatch in the allowable stress in the flaw assessment for a pipe with a circumferential crack. Some past fracture test results of pipes showed that flawed pipes did not fracture at the flaw section when the circumferential flaw size was small and they failed by oval deformation or plastic buckling. Allowable stress for such behavior has been incorporated in some existing design codes as a restriction for plastic collapse. Through the reevaluation of the existing piping fracture test results, the applicability of fracture evaluation methods defined in the FFS code was examined for the case that flaw size was very small. As a result, the fracture evaluation method based on flow stress was found not to be applicable when flaw size was very small, and the failure criterion in this case depended on the collapse strength accompanying with ovalization. Revisions of the FFS code reflecting these examination results were proposed in this paper.
Reliability of Water Jet Peening as Residual Stress Mitigation
Authors: Kono Yusuke , Okimura Koji , Tajima Masakazu , Noda Masaki
Published: November 2014

As a countermeasure against high residual stress, some residual stress improvement methods have been developed; Water Jet Peening (WJP) [1] [2] for components installed in water, Shot Peening by Ultrasonic-wave vibration (USP) for components installed in air, and outer surface irradiated Laser Stress Improvement Process (L-SIP)[3] for components that can only be accessed from the outer surface.

WJP is applied to Reactor Vessel (RV) outlet/inlet nozzle safe-end joints (Alloy600 weld metal), RV Bottom Mounted Instrument (BMI) inner surface and J-weld. Especially, it is difficult to apply the technology to BMI because BMI inner surface is a very narrow space (inner diameter; approximately 10–15mm) and BMI J-weld configuration is a complicated 3-dimensional form.

On the occasion of actual application, the verification tests have been carried out and checked that a stress improvement was effective as one of PWSCC mitigations. And the compressive stress induced by the WJP was verified to continue to exist under actual plant operation conditions.

Thus, in addition to replacing the material with Alloy 690, converting the residual stress to compressive one can prevent the occurrence of PWSCC.
Validation of a Microwave Based Inspection System for HDPE Butt Fusions
Authors: Stakenborghs Robert J.
Published: November 2014

The use of High Density Polyethylene (HDPE) is growing rapidly due to its corrosion resistance characteristics and ease of construction when compared to metal piping systems. As a result of its widespread use, a method of inspecting the piping joints is becoming essential to ensure safe, sound piping systems. This is particularly true for butt fusion joints, which can contain micro-structural defects that impact long term integrity of the piping system. These defects have proven to be difficult to detect using traditional means of inspection, such as ultrasound, because these micro-structural defects do not result in an acoustic reflector or impedance difference.

This paper presents the results of a rigorous validation program for a microwave non-destructive inspection technique for HDPE butt fusions. The program includes inspection of a cross section of defect types that comprise geometric type defects, such as back and side drilled holes, and butt fusion inclusions. It also includes defects of types commonly found in field applications, such as grass, oil, fine particulate and other contaminants and procedural deviations, such as low and high pressure and longer than typical dwell times (wait time between heating the pipe ends and fusing them). The success of the microwave inspection protocol and equipment in detecting the many types of defects that comprise the set of samples has been reduced to Probabilities of Detection (POD) and Probabilities of False Alarm (POFA). These statistics have been calculated in a traditional fashion and are presented in this paper.
Failure Analysis of a Cracked Pipe Clamp
Authors: French Stephen M.
Published: November 2014

Following the in-service failure of a pipe clamp on one of two combustion turbines (CT-2, for reference) at a natural gas fired combined cycle unit, station personnel found three other pipe clamps in CT-1 that were similarly damaged. One of the cracked pipe clamps from CT-1 was submitted to the metals laboratory for analysis to determine the cause of the failure. Subsequently, a piping segment and one additional clamp from CT-2 was submitted to the lab for analysis of the external deposit and were found to contain similar cracks in the clamp. The clamps are used to secure the steam piping to the outlet portion of the transition pieces within the CT. Analysis of the cracks identified them as intergranular, initiating on the ID surface of the clamp (where the applied stresses of the clamp are in tension) but which would be external to the pipe itself. Analysis of the actual deposits showed them to be very high in sulfur (soluble anion analysis identified them as sulfates) and minor amounts of fluorides, with no detectable chlorides either by SEM/EDS or by soluble anion analysis. The area is washed down during shut-down and an analysis of the washwater additive showed very low levels of chloride (7ppm) and sulfate (4 ppm). Concentration of chlorides could be occurring as the units heat up, but none could be identified on the actual fracture surface or the deposit with any certainty. The cracking is consistent with intergranular stress-corrosion cracking, although a specific causative agent/environment could not be identified with any certainty. Given the operating temperatures, any SCC that would be occurring would likely be during shut-down or start-up in order for an aqueous environment to be present. The final disposition of these clamps is for regular replacement during the routine overhauls.
Residual Stress Evaluation of Small Diameter Stainless Steel Piping by Experimental Measurements and Finite Element Analysis
Authors: Hicks Trevor G. , Mabe William R. , Miller Jason R. , Mullen John V.
Published: November 2014

Residual stresses within stainless steel pipe welds may impact both component inspections and in-service cracking. Various investigators have examined piping residual stresses in large diameter piping using both finite element modeling and experimental techniques, but limited information is available for small diameter piping. This investigation uses both experimental methods and analytical modeling to evaluate the impact of welding on the residual stresses along the inner diameter (ID) of two small diameter pipe specimens.

Results of the investigation showed that tensile axial residual stresses were observed in the heat affected zone (HAZ) along the ID of the thin-wall pipe specimen with distinct regions of tensile and compressive axial stress which correlate well with the location where the last weld segments of the final weld pass were deposited. Higher stresses were also observed in the HAZ on the side where the final weld pass was deposited. By contrast, testing of the thick-wall pipe specimen showed significantly lower levels of tensile stresses along the pipe ID with the higher stress regions being biased toward the pipe outer diameter (OD).
Stability of Blasius Boundary-Layer Flow Interacting With a Compliant Panel
Authors: Tsigklifis Konstantinos , Lucey Anthony D.
Published: November 2014

We develop a model to study the fluid-structure interaction (FSI) of a compliant panel with a Blasius boundary-layer flow. We carry out a two-dimensional global linear stability analysis modeling the flow using a combination of vortex and source boundary-element sheets on a computational grid while the dynamics of a plate-spring compliant wall are represented in finite-difference form. The system is then couched as an eigenvalue problem and the eigenvalues of the various flow- and wall-based instabilities are analyzed for two distinct sets of system parameters. Key findings are that coalescence — or resonance — of a structural eigenmode with either the most unstable flow-based Tollmien-Schlichting Wave (TSW) or wall-based travelling-wave flutter (TWF) modes can occur. This renders the convective nature of these instabilities to become global for a finite compliant wall, a phenomenon that has not hitherto been reported in the literature.
An Overview of IAEA Technical Guidelines on Fluid-Structure Interaction
Authors: Kim M. , Hughes P. , Ainsworth R. A.
Published: November 2014

This paper provides an overview of International Atomic Energy Agency (IAEA) draft technical guidelines on Fluid-Structure Interaction (FSI), which is supporting document for IAEA Safety Standards aimed at providing method and practices. The technical guidelines are based on sections in codes and standards, more general documents on FSI and documents describing particular plant issues or problems. The technical guidelines recognise that FSI has led to a range of problems in a range of reactor types including: flow-induced vibration in light water reactor (LWR) steam generators under external loading including seismic loading; fretting of LWR heat exchangers with the fretting loading dependent on cross-flow velocity; seismic effects and fluid sloshing in liquid metal cooled faster breeder reactor (LMFBR); and water hammer. In addition to providing an overview description of the technical guidelines, the paper also describes the process followed to produce and obtain peer review of the document.
A Numerical Study of Turbulence Generation and Induced Stresses in Pressure Reducing Orifice
Authors: Gabr Mahmoud M. M. , Younan Maher Y. A. , El-Baz Ahmed M. R.
Published: November 2014

In the present paper, a numerical fluid flow and induced stresses are studied for single hole and multi-hole orifice plates. Three multi hole configurations are studied; orifice with 3 holes, 5 holes and 7 holes. Turbulence characteristics behind each configuration are analyzed and orifice geometry strength and safety factor are assessed. The multi-hole orifice showed promising results in reducing the turbulence which would increase the system reliability and performance. On the other hand, multi-hole orifice showed weaker strength for same orifice plate thickness and higher probability for pipe wall erosion.
Numerical Analysis of a RHR Piping System Subjected to Seismic Loading
Authors: Shen Ming-Yi , Lai Zih-Yu , Chai Juin-Fu , Lin Fan-Ru , Huang Yin-Nan , Yu Ching-Ching
Published: November 2014

The objective of this study is to build a credible numerical model using SAP2000 for fragility analysis of RHR piping system, and to establish the load pattern of a cyclic loading test to identify the seismic vulnerability of the system. The RHR piping system selected for test and numerical analysis is duplicated from a part of the RHR system in a nuclear power plant (NPP) in Taiwan, and this part is distributed between the floor of the reactor building (RB) to the wall of the reinforced concrete containment vessel (RCCV) of the sample NPP.

The numerical model for the sample RHR piping system was developed, and the nonlinear response-history analysis was conducted using input motions compatible with the floor response spectrum at the anchor points of the sample piping system subjected to Safe Shutdown Earthquake (SSE). Based on the distribution of resultant inertial forces and the responses at critical locations of the piping system under SSE, the magnitudes and locations of the equivalent concentrated static loads were determined and used in the pushover analysis to estimate the capacity of the RHR piping system. The numerical results will be verified by the aforementioned cyclic loading test. More studies are on the way including shaking table test and fragility analysis for the sample piping system to further identify the seismic performance and risk of the system.
Heroic Radio: A Study of Radio Responses in the Immediate Aftermath of the September 2010 Earthquake in Christchurch, New Zealand
Authors: Zanker Ruth
Published: November 2014

This case study examines radio’s performance in the immediate hour after the 7.1 Richter scale earthquake struck Christchurch, the largest city in the South Island of New Zealand, at 4.35am on September 4th 2010. It contributes to a growing body of work analysing media responses to sudden catastrophic events like floods, bushfires, tsunamis and earthquakes and it refocuses attention on the critical role played by the ‘legacy’ medium of radio at a time when the popular media is focused on the value of social media in crises. Media commentary, interviews and transcripts of broadcasts are used to explore how radio performed in the hour of darkness immediately after the first quake and before a civil emergency was declared. The study compares the performance of two national talk back networks and Radio New Zealand National, a public service network. It explores the relationship between local informants and national media centres hungry for on the ground information. It concludes with a discussion of the role of radio in this and future crises.
Social Media, Crisis Mapping and the Christchurch Earthquakes of 2011
Authors: Beatson Abi , Buettner Angi , Schirato Tony
Published: November 2014

This article will describe and contextualize the development whereby data and information flows derived from social media sites are gathered and made available as part of crisis maps. In particular it will look at the evidence available to describe and contextualise the use of crisis mapping as it was played out during the initial recovery period of the 2011 Christchurch earthquakes. It will also consider to the extent to which this new media based institutional and public information sharing and deployment constitutes a significant tool within the relevant networks of communication practices and practitioners.
Models and methods for analyzing DCE‐MRI: A review
Authors: Khalifa Fahmi , Soliman Ahmed , El‐Baz Ayman , Abou El‐Ghar Mohamed , El‐Diasty Tarek , Gimel'farb Georgy , Ouseph Rosemary , Dwyer Amy C.
Published: November 2014

Purpose:

To present a review of most commonly used techniques to analyze dynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI), discusses their strengths and weaknesses, and outlines recent clinical applications of findings from these approaches.

Methods:

DCE‐MRI allows for noninvasive quantitative analysis of contrast agent (CA) transient in soft tissues. Thus, it is an important and well‐established tool to reveal microvasculature and perfusion in various clinical applications. In the last three decades, a host of nonparametric and parametric models and methods have been developed in order to quantify the CA's perfusion into tissue and estimate perfusion‐related parameters (indexes) from signal‐ or concentration–time curves. These indexes are widely used in various clinical applications for the detection, characterization, and therapy monitoring of different diseases.

Results:

Promising theoretical findings and experimental results for the reviewed models and techniques in a variety of clinical applications suggest that DCE‐MRI is a clinically relevant imaging modality, which can be used for early diagnosis of different diseases, such as breast and prostate cancer, renal rejection, and liver tumors.

Conclusions:

Both nonparametric and parametric approaches for DCE‐MRI analysis possess the ability to quantify tissue perfusion.
Anatomical background noise power spectrum in differential phase contrast and dark field contrast mammograms
Authors: Garrett John , Ge Yongshuai , Li Ke , Chen Guang‐Hong
Published: November 2014

Purpose:

In x‐ray absorption mammography, it has been found that the anatomical background noise can be characterized by a power law dependence on the spatial frequency, NPSa(f) ≈ αf−β. In this letter, the authors present the first experimental results of the corresponding exponents, β, for differential phase contrast (βDPC) and dark field contrast (βDF) mammography.

Methods:

A grating‐based x‐ray multicontrast imaging acquisition benchtop system was used to simultaneously acquire mammograms with three different contrast mechanisms from 15 cadaver breasts under the same x‐ray data acquisition conditions. The cadaver breasts were imaged in the coronal plane. The authors’ experimental implementation of the well documented method [Burgess, Jacobson, and Judy, Med. Phys. 28, 419–437 (2001)] to extract the exponent β was first validated using anonymized clinical mammograms. Experiments were then used to determine β for the three types of mammograms for each cadaver breast acquired with our multicontrast imaging system: absorption contrast mammogram (βAbs.), differential phase contrast mammogram (βDPC), and dark‐field contrast mammogram (βDF).

Results:

The measured β values, acquired in the coronal plane with the benchtop multicontrast imaging system are βAbs. = 3.61 ± 0.49, βDPC = 2.54 ± 0.75, and βDF = 1.44 ± 0.49 for absorption, differential phase, and dark field mammogram, respectively.

Conclusions:

The β values for differential phase contrast and dark field mammography are significantly lower than the measured value of β for the corresponding absorption contrast mammograms. The greatly reduced β value of the anatomical background noise in differential phase contrast and dark field mammograms may suggest potentially improved diagnostic performance for certain types of breast cancer imaging tasks.
Radiotherapy beyond cancer: Target localization in real‐time MRI and treatment planning for cardiac radiosurgery
Authors: Ipsen S. , Blanck O. , Oborn B. , Bode F. , Liney G. , Hunold P. , Rades D. , Schweikard A. , Keall P. J.
Published: November 2014

Purpose:

Atrial fibrillation (AFib) is the most common cardiac arrhythmia that affects millions of patients world‐wide. AFib is usually treated with minimally invasive, time consuming catheter ablation techniques. While recently noninvasive radiosurgery to the pulmonary vein antrum (PVA) in the left atrium has been proposed for AFib treatment, precise target location during treatment is challenging due to complex respiratory and cardiac motion. A MRI linear accelerator (MRI‐Linac) could solve the problems of motion tracking and compensation using real‐time image guidance. In this study, the authors quantified target motion ranges on cardiac magnetic resonance imaging (MRI) and analyzed the dosimetric benefits of margin reduction assuming real‐time motion compensation was applied.

Methods:

For the imaging study, six human subjects underwent real‐time cardiac MRI under free breathing. The target motion was analyzed retrospectively using a template matching algorithm. The planning study was conducted on a CT of an AFib patient with a centrally located esophagus undergoing catheter ablation, representing an ideal case for cardiac radiosurgery. The target definition was similar to the ablation lesions at the PVA created during catheter treatment. Safety margins of 0 mm (perfect tracking) to 8 mm (untracked respiratory motion) were added to the target, defining the planning target volume (PTV). For each margin, a 30 Gy single fraction IMRT plan was generated. Additionally, the influence of 1 and 3 T magnetic fields on the treatment beam delivery was simulated using Monte Carlo calculations to determine the dosimetric impact of MRI guidance for two different Linac positions.

Results:

Real‐time cardiac MRI showed mean respiratory target motion of 10.2 mm (superior–inferior), 2.4 mm (anterior–posterior), and 2 mm (left–right). The planning study showed that increasing safety margins to encompass untracked respiratory motion leads to overlapping structures even in the ideal scenario, compromising either normal tissue dose constraints or PTV coverage. The magnetic field caused a slight increase in the PTV dose with the in‐line MRI‐Linac configuration.

Conclusions:

The authors’ results indicate that real‐time tracking and motion compensation are mandatory for cardiac radiosurgery and MRI‐guidance is feasible, opening the possibility of treating cardiac arrhythmia patients completely noninvasively.
Processing On-the-Go in Exosomes
Authors: Ferrarelli Leslie K.
Published: November 2014

Breast cancer cells secrete exosomes carrying microRNA-processing proteins that promote malignant transformation in normal cells.
Dissemination of NDM Metallo-β-Lactamase Genes among Clinical Isolates of Enterobacteriaceae Collected during the SMART Global Surveillance Study from 2008 to 2012
Authors: Biedenbach D. , Bouchillon S. , Hackel M. , Hoban D. , Kazmierczak K. , Hawser S. , Badal R.
Published: November 2014

The prevalence of carbapenemase enzymes continues to increase. Among the Ambler class B enzymes is the New Delhi metallo-β-lactamase (NDM). This particular enzyme is capable of hydrolyzing nearly all β-lactam antimicrobial agents and has spread rapidly, becoming a global problem. Therapeutic treatment options for patients infected with isolates which produce this enzyme are difficult to manage, as cross-resistance to other antimicrobial classes is common. The Study for Monitoring Antimicrobial Resistance Trends (SMART) is a global surveillance study evaluating the antimicrobial susceptibilities of numerous Gram-negative bacterial species recovered from people with intra-abdominal and urinary tract infections. The Clinical and Laboratory Standards Institute methods and a molecular analysis identified 134 isolates of
Enterobacteriaceae
(nine species) and one
Acinetobacter
sp. with
bla
NDM
genes. These isolates were collected in nine countries, and >95% of the isolates possessed the NDM-1 variant. The MIC
90
values were >4 mg/liter and >8 mg/liter for ertapenem and imipenem, respectively. No tested β-lactam or β-lactamase inhibitor combination had activity against these isolates. Resistance to amikacin (79.9%) and levofloxacin (82.8%) was common. Nearly all the isolates encoded additional enzymes, including AmpC cephalosporinases and extended-spectrum β-lactamases. There is an urgent need for infection control and continued global monitoring of isolates which harbor the NDM enzyme, as evidenced by recent outbreaks.