bluuebunny/crossref_metadata_2025 huggingface dataset:
Release From Regulatory Control
Authors: Cooper John R.
Published: March 2009

Release of materials from regulatory control is an important process; it reduces the amounts of radioactive waste requiring disposal and serves to conserve resources. This paper discusses the radiological protection principles and criteria that apply to the release of materials and land from regulatory control. Comparisons are drawn between materials containing artificial radionuclides and those containing natural radionuclides. Materials within regulated practices are subject to controls. Stringent requirements are placed on the disposal of radioactive wastes in order to protect man and the environment from the effects of ionising radiation. These requirements are generally linked to the hazard posed by the waste and may include disposal at defined locations, environmental monitoring around the point of disposal and assessment of the doses or risks to exposed individuals for comparison with protection criteria (eg, dose limits and constraints). Logically, there should come a point where the radiological hazard posed by the material is such that regulatory controls can be removed and the materials can be released into the general environment without further consideration. Release of materials from regulatory controls has a number of advantages. For example, it allows regulatory effort to be focussed on areas of significant potential hazard and would help to avoid expensive disposal space being needlessly occupied by materials of very low activity content. Recycling of economically valuable materials would also contribute to sustainable development. Nevertheless, it is important to avoid the connotation that radioactive waste is being dumped on the public; the process for release from regulatory controls should be transparent and soundly based on radiological protection considerations. This paper considers both the release of materials from regulatory controls from licensed nuclear sites and the release of land previously occupied by a licensed nuclear site. Comparisons are made with land and materials contaminated with natural radionuclides. It owes much to discussions with staff at the International Atomic Energy Agency (IAEA) and draws heavily on the conclusions of the International Conference on ‘Safe Decommissioning for Nuclear Activities’ held in Berlin in 2002. The opinions, however, are those of the author.
Status and Challenges in D&D of Nuclear Facilities in NEA Countries: Activities of the NEA Working Party on Decommissioning and Dismantling
Authors: Pescatore Claudio , Duncan Allan , Warnecke Ernst , Gordelier Stan
Published: March 2009

OECD Member countries will be faced increasingly with the task of decommissioning and dismantling nuclear facilities with a view to final release of sites. The OECD/NEA Working Party on Management of Materials from Decommissioning and Dismantling (WPDD) is tasked with keeping under review policy, strategy, and the regulatory aspects of decommissioning and dismantling of obsolete nuclear installations up to and including the ultimate release of sites. Reflections and products directed both to specialists, to opinion formers and to the interested public are being generated and released in hard copy or web-based. The activities of the WPDD are reviewed in this paper. Emphasis is placed on the main points of a recent publication that provides, in non-specialist terminology, a concise overview of the status of D&D of nuclear facilities in NEA Member countries.
Arctic Military Environmental Cooperation Project 1.5-1 Radiation Control at Facilities: Application of the PICASSO System
Authors: Sanders J. , Pomerville J. , Moskowitz Paul D.
Published: March 2009

The Arctic Military Environmental Cooperation (AMEC) is a cooperative effort between military establishments of the Russian Federation, United States, and Norway to reduce potential environmental threats from military installations and activities in the Arctic region and enhancing the environmental security of all three countries. The goal of this project is to enhance the ability of the Russian Navy to effectively and safely perform radioecological monitoring of sites at facilities dismantling nuclear submarines and handling and disposition of spent nuclear fuel (SNF) and the radioactive waste by-products. Radioecological monitoring is needed to protect workers at the sites engaged in work involving the dismantlement of nuclear submarines, the local public of the surrounding communities, and the environment. Radioecological monitoring is being accomplished by the installation of a centralized radiological surveillance system, the PICASSO Environmental Monitoring system developed by the Institute for Energy Technology, Halden, Norway. The Russian Institute for Nuclear Safety, Moscow, Russia, modified the system for use at Russian Federation Naval bases and developed a working model for its intended application. The working model includes Russian manufactured terrestrial and underwater gamma detectors, smart controllers, radiomodems for off-site transmission of data coupled with the PICASSO Environmental Monitoring system installed into local computers, work stations, and a centralized server to monitor the real-time activity of the particular site. The selected sites for installation of PICASSO are the Polyarninsky Shipyard No. 10 and the RTP Atomflot shipyards. The AMEC project teams visited Polyarninsky Shipyard No. 10 and the RTP Atomflot shipyards in June 2003 to monitor the progress of the installation of the detection and monitoring systems. The implementation of the PICASSO system will be integrated with other AMEC projects at both sites. Plans are being developed to implement the use of this system at most Russian Federation Naval sites handling SNF.
Study of Interface Roughness Influence on Thermal Resistance Across Double-Layered Films by Molecular Dynamics Simulation
Authors: Liang Xin-Gang , Sun Lin
Published: March 2009

This study investigates the rough interface influence on the thermal resistance across double-layered thin films using Non-Equilibrium Molecular Dynamics (NEMD) with Lennard-Jones potential. Layer A is solid argon with face-centered structure. Layer B is obtained by changing atomic mass only. When each contacting atomic plane from the two layers has the same kind of atoms a flat interface is formed. When all the atoms in the nearest atomic plane to the interface in layer A are replaced with atom B and all the atoms in the nearest atomic plane to the interface in layer B are substituted by atoms A “rough interface” is obtained. Under flat and interface conditions the temperature profile, vibration amplitude and structure factor are studied to exhibit the roughness effect. It is found that the rough interface can effectively reduce the normal thermal resistance caused by the mismatch of the two dissimilar materials. This result suggests a possibility to control the thermal conductivity of the double-layered structure by engineering its interface condition.
Interface Motion Driven by Capillary Action in Microchannel
Authors: Ichikawa Naoki , Maeda Ryutaro
Published: March 2009

In microchannel flow, gas-liquid interface behavior will be important for developing a wide range of microfluidic applications, especially in micro reactors. In this paper, we discuss some topics related to capillary action and two-phase fluid behavior in a microchannel. One of the topics is interface motion in the flow driven only by capillary action. We examined circular and rectangular microchannel with diameter of 50 μm and 100 μm × 67 μm, respectively. For the circular channel, experiments well agreed with the previous theory in the case of ethyl alcohol as the test liquid. The effects of inner surface condition are found to be critical for interface motion on a microscopic scale. We have extended our theory to a rectangular microchannel. We obtained the same formula of relation between non-dimensional time and interface position as that of the circular channel. We compared predictions with experimental results of a PDMS microchannel. They agreed qualitatively, but not quantitatively. The difference was considered to be caused by contact angle estimation.
Mathematical Modeling of Constrained Vapor Bubbles
Authors: Ajaev Vladimir S. , Homsy G. M.
Published: March 2009

We develop a mathematical model of a long vapor bubble in a micro-channel with given temperature distributions on the walls. We assume that the shape of the bubble is dominated by capillary forces everywhere except near the walls of the channel and use a lubrication-type analysis to find the local vapor-liquid interface shapes and mass fluxes near the walls. Both two- and three-dimensional steady-state solutions are found such that evaporation near the heated bottom is balanced by condensation in colder areas of the vapor-liquid interface. The total length in this steady regime is found from the integral mass balance and investigated as a function of heating conditions. Steady-state conditions can no longer be satisfied when the intensity of heating is above a certain level. In this regime the bubble is expanding. We investigate such expansion in the framework of a two-dimensional model in the limit of small capillary number.
Analytical and Numerical Modeling of Microchannel Heat Sink
Authors: Cossali G. E. , Di Pietro D. A. , Marengo M.
Published: March 2009

Analytical and numerical tools for modeling microchannel heat sinks are presented, including the most important project parameters. An analytical 1D model, suitable for both design and performance calculations, is first developed under lumped capacitance assumption and resorting to standard correlations for Nu under H1 boundary conditions. 2D model extensions are then provided separately for poorly and highly conductive substrates: in the former case axial conduction is neglected; in the latter case the 2D model is modified to include axial conduction by exploiting the results from 1D model. This innovative approach provides a significant reduction in computational costs with respect to a conventional 3D model. A 3D model is then developed to evaluate the effects of thermal entrance. Finally, some optimization calculations are performed.
Three-Dimensional Thermal Analysis of Heat Sinks With Circular Cooling Micro-Channels
Authors: Kroeker C. J. , Soliman H. M. , Ormiston S. J.
Published: March 2009

The pressure drop and heat transfer characteristics of heat sinks with circular micro-channels are investigated using the continuum model consisting of the conventional Navier-Stokes equations and the conventional energy equation. Developing flow (both hydrodynamically and thermally) is assumed in the fluid region and three-dimensional conjugate heat transfer is assumed in the solid region. Thermal results based on this approach are shown to be in good agreement with existing experimental data. Numerical results obtained for heat sinks with various geometries indicate that the heat absorbed by the fluid per unit length is high at the inlet and decreases steadily in the flow direction. As a result, the bulk temperature increases at a higher rate near the inlet. The geometry of the heat sink is shown to have a significant effect on the overall thermal resistance.
Heat Transport Limitation of a Triangular Micro Heat Pipe
Authors: Sugumar D. , Tio Kek Kiong
Published: March 2009

A micro heat pipe will operate effectively by achieving its maximum possible heat transport capacity only if it is to operate at a specific temperature, i.e., design temperature. In reality, micro heat pipe’s may be required to operate at temperatures different from the design temperature. In this study, the heat transport capacity of an equilateral triangle micro heat pipe is investigated. The micro heat pipe is filled optimally with working fluid for a specific design temperature and operated at different operating temperatures. For this purpose, water, pentane and acetone was selected as the working fluids. From the numerical results obtained, it shows that the optimal charge level of the micro heat pipe is dependent on the operating temperature. Furthermore, the results also shows that if the micro heat pipe is to be operated at temperatures other than its design temperature, its heat transport capacity is limited by the occurrence of flooding at the condenser section or dryout at the evaporator section, depending on the operating temperature and type of working fluid. It is observed that when the micro heat pipe is operated at a higher temperature than its design temperature, the heat transport capacity increases but limited by the onset of dryout at the evaporator section. However, the heat transport capacity decreases if it is to be operated at lower temperatures than its design temperature due to the occurrence of flooding at condenser end. From the results obtained, we can conclude that the performance of a micro heat pipe is decreased if it is to be operated at temperatures other than its design temperature.
A Study of the Fabrication and Analysis of Micro Diffuser/Nozzles
Authors: Yang Kai-Shing , Chen Ing-Young , Shew Bor-Yuan , Wang Chi-Chuan
Published: March 2009

In this study, an analysis of the performance of micro nozzle/diffusers is performed and fabrication of the micro nozzle/diffuser is conducted and tested. It is found that the pressure loss coefficient for the nozzle/diffuser decreases with the Reynolds number. At a given Reynolds number, the pressure loss coefficient for nozzle is higher than that of the diffuser due to considerable difference in the momentum change. For the effect of nozzle/diffuser length on the pressure loss coefficient, it is found that the influence is rather small. At a fixed volumetric flowrate, a “minimum” phenomenon of the pressure loss coefficient vs. nozzle/diffuser depth is encountered. This is related to the interactions of velocity change and friction factor. Good agreements of the measured data with the predicted results are found in this study except at a diffuser having an opening angle of 20° . It is likely that the departure of this case to the prediction is due to the separation phenomenon in a larger angle of the diffuser.
Pulsed Injector Induced Mixing in High Aspect Ratio Microchannel Flow
Authors: Siripoorikan B. , Liburdy J. A. , Pence D. V.
Published: March 2009

Micro-fluid mixing is an important aspect of many of the various micro-fluidic systems used in biochemical production, biomedical industries, microenergy systems and some electronic devices. Active or highly effective passive mixing techniques are often required. In this study, two pulsed injectors are used to actively enhance mixing in a high aspect ratio microchannel (125 μm deep and 1 mm wide). The main channel has two adjacent flowing streams with 100% dye and 0% dye concentrations, respectively. Two injectors (125 μm deep and 250 μm wide) are located on opposite sides of the channel and off-set in the downstream direction. A dye solution is used to map local mixing throughout the channel by measuring concentration variations as a function of both space and time. Images of the concentration variations within the channel are used to quantify mixing. It is shown that there is a high degree of repeatability of concentration distribution as a function of phase of the pulsing cycle. The flow rate ratio between the injectors and main channel is found to be the most influential parameter on overall mixing, and evidence of an optimal flow rate ratio and frequency is presented. A nondimensional correlation is presented that could be used to predict the level of mixing for the conditions studied.
Laminate Mixing in Micro-Scale Fractal-Like Merging Channel Networks
Authors: Enfield Kent E. , Siekas Jeremy J. , Pence Deborah V.
Published: March 2009

A two-dimensional model was developed to predict concentration profiles resulting from passive, or diffusive, mixing of laminated layers formed in a fractal-like merging flow network. Both uniform and parabolic velocity profiles were considered in the model. Concentration profiles were experimentally acquired near the top surface of the flow network using laser induced fluorescence. The degree of mixing was assessed from concentration profiles at the end of each channel. Although the degree of mixing from the two-dimensional model well predicts the trend of the experimental degree of mixing, the numerical model under predicts the experimental values by approximately 25 percent. This may be due in part to the presence of top and bottom walls in the experimental device. These walls tend to slow the flow in this region, thereby increasing the residence time and improving the mixing. These top and bottom walls are neglected in the two-dimensional model. For the existing flow network, the degree of mixing is provided as a function of Peclet number. The degree of mixing is further investigated by varying the number of branching levels, the width of the initial flow channels, and the total flow length for a fixed Peclet number. A nondimensional parameter is established that serves as a design tool for predicting an optimum number of branching levels for fixed values of the total flow length, initial branch width and channel depth.
Micro-PIV Investigation of a Sinusoidal Crossflow Microfiltration Module
Authors: Mielnik Michal M. , Sætran Lars R.
Published: March 2009

A micro-PIV system is presented in detail, pointing out important aspects of micro-PIV system design cruicial for its operation. The micro-PIV system is then applied on a sinusoidal microchannel, and the fluid motion inside the device is presented and discussed. The wall shear stress at the waist of the channel is measured to be up to 60% higher than the wall shear stress in a conventional parallel-plate flow. The results suggest that altering of channel geometry may contribute to better design of cross-flow microfiltration units, in terms of reduced clogging by shear-control of bacterial motion. Furthermore, the flow is shown to exhibit a strong Reynolds number dependence, characterised by the onset of periodic distortion imposed on the flow by the sinusoidal walls occuring between Re = 2 and Re = 10.
Performance Improvements at the Boardman Coal Plant as a Result of Testing and Input/Loss Monitoring
Authors: Rodgers David A. T. , Lang Fred D.
Published: March 2009

This paper presents methods and practices of improving heat rate through testing and, most importantly, through heat rate monitoring. This work was preformed at Portland General Electric’s 585 MWe Boardman Coal Plant, which used two very different Powder River Basin and Utah coals ranging from 8,100 to over 12,500 Btu/lbm. Such fuel variability, common now among coal-fired units was successfully addressed by Boardman’s on-line monitoring techniques. Monitoring has evolved over the past ten years from a Controllable Parameters approach (offering disconnected guidance), to a systems approach in which fuel chemistry and heating value are determined on-line, their results serving as a bases for Second Law analysis. At Boardman on-line monitoring was implemented through Exergetic System’s Input/Loss Method. Boardman was one of the first half-dozen plants to fully implement Input/Loss. This paper teaches through discussion of eight in-plant examples. These examples discuss heat rate improvements involving both operational configurations and plant components: from determining changes in coal chemistry and composite heating value on-line; to recognizing the impact of individual rows of burners and pulverizer configurations; to air leakage identifications; to examples of hour-by-hour heat rate improvements; comparison to effluent flows; etc. All of these cases have applicability to any coal-fired unit.
Heat Flux Evaluation in a Test Furnace Equipped With High Temperature Air Combustion (HTAC) Technique
Authors: Lille Simon , Blasiak Wlodzimierz , Mo¨rtberg Magnus , Dobski Tomasz , Yang Weihong
Published: March 2009

High Temperature Air Combustion has already been applied in various industrial furnaces. Steel producers use most of the revamped furnaces. These are: • Batch and continuous heating furnaces in which HRS burners with open flames were used, • Batch and continuous heat treatment furnaces in which HRS burners with radiant tubes were used. Apart from steel industry the HTAC systems were applied to melt aluminium or to incinerate odour, vapour gases for example in pulp and paper industry. In all these applications very high fuel savings (sometimes as high as 60%), reduction of NOx and production increase (by 20–50%) was achieved. Progress in applications of the HTAC increased also needs of more information and data required by furnace and process designers. For this reason study in larger scale where at least one set of regenerative burner systems is installed are very much needed. Aim of such studies is not only to verify furnace performance with respect to the known general advantages of HTAC but are focused on specific problems related to furnace and high-cycle regenerative burners operation, process and product properties or type of fuels used. Parallel to the semi-industrial tests numerical models of furnaces have to be developed and verified. In this work, mainly results of heat flux measurements as well as results of numerical modeling of heat transfer in the HTAC test furnace are presented. Results were obtained for propane combustion at firing rate equal to 200 kW. The general code, STAR-CD, was employed in this work to analyse the HTAC test furnace numerically. HTAC test furnace at Royal Institute of Technology (KTH) with capacity of 200 kW was used in this work. The furnace is equipped with two different high-cycle regenerative systems (HRS). In both systems the “honeycomb” regenerator is used. The two-burner system is made of two pairs (four burners) of high cycle-regenerative burners with switching time between 10 and 40 seconds. HTAC test furnace is equipped with four air-cooled tubes to take away heat from the furnace. The total radiative heat flux measured in the HTAC furnace shows very uniform distribution over the whole combustion chamber. For total radiative heat flux, the values are in the range of 110–130 kW/m2 as measured by means of the total radiative heat flow meter at the furnace temperature 1100 C. Average total radiation flux on the top furnace wall is as high as 245.5 kW/m2 as well as total incident radiation flux. Total radiation heat flux on the air-cooled tube surface is very uniform along and around the tubes. Average radiant heat flux taken away by air cool tube is 35.46 kW/m2.
Vortex Tube Applications in Micro-Power Generation
Authors: Arslan Selin , Mitrovic Bojan , Muller Michael R.
Published: March 2009

The purpose of this paper is to study vortex tube performance characteristics and the use of vortex tubes to increase the total efficiency of power systems, especially micropower systems. A vortex tube is a device in which compressed air is made to swirl and separate into two low-pressure streams, one with higher temperature than the entry and the other lower. The lack of moving parts and electricity make the vortex tube attractive for a number of specialized applications where simplicity, robustness and reliability are desired. Vortex tubes are currently used for industrial cooling applications, separation technologies, and chemical analysis. It is well known that the temperature difference between the hot and cold sides of the vortex tube scales with the pressure drop. Also, at any pressure drop, the temperatures and flow rates are dependent on the flow fractions between the hot and cold sides. Data is available for large pressure drops, but this paper presents experimental results at low-pressure drops optimizing the operational modes for various applications. The micro-power systems under consideration include micro-turbines, which evolved out of automotive turbocharger technology. The use of vortex tubes in power systems has received some attention but the use of both the hot and cold streams has never been considered. In this work, we consider such dual use. As an example of an application, the vortex tube is considered in conjunction with a heat recovery steam generator (HRSG). The vortex tube splits the turbine exhaust flow into hotter and cooler streams. The cooler stream is still hot enough to supply all needed heat in the economizer section, leaving the hotter stream to increase the exit temperature from the superheater. In this way both the air leaving the HRSG and going to the steam turbine will have an increased enthalpy and cycle efficiencies are improved. In addition, steam turbine exit quality is increased.
Improving Power Plant Availability Through Advanced Engine Diagnostic Techniques
Authors: Sampath Suresh , Ogaji Stephen , Singh Riti
Published: March 2009

Technological advances and high cost of ownership have resulted in considerable interest in advanced maintenance techniques. Quantifying fault and consequently availability requires the use of gas turbine and combined cycle models able to undertake appropriate diagnostics and life cycle costing. These are complex areas as they include the simulation of such issues as performance and assessment of degraded gas turbines, life usage and risk analysis. This paper describes how the recent developments in engine diagnostics using advanced techniques like Artificial Neural Networks (ANN) and Genetic Algorithm (GA) based technique have opened new opportunities in the field of engine fault diagnostics. It also discusses the potential of advanced engine diagnostics using such features as ANN and GA in contributing to the management of availability for industrial gas turbines.
Calculation Cross-Reference Database
Authors: Wilson Gregory C. , Wooten Keith D.
Published: March 2009

Calculations form the backbone of every design. Engineers and designers rely on calculations to support the technical adequacy of any system, structure or component (SSC). Without representative calculations, the design, construction, operation, maintenance or modification of any SSC would remain unanalyzed, non-configured and potentially unsafe. In today’s nuclear generating plants, calculations that form the design basis and how that design is translated into drawings and procedures are especially important. Federal regulations mandate that all nuclear generating plant licensees establish a method of design control to assure that regulatory requirements are met. The purpose of this paper is to describe one such method by which a nuclear plant licensee (Southern Nuclear) controls its calculations.
Prompt Leak Detection for High Pressure Feedwater Heaters
Authors: Kidwell Steven A.
Published: March 2009

I. THE NEED. A. In high pressure feedwater heaters, a tube leak quickly claims several neighboring tubes as collateral victims. B. Prompt detection of the initial leak would save the neighboring tubes from damage and preclude a potential turbine water induction incident. II. EXAMPLE. A. A Midwest generating station replaced 12 old high pressure heaters. The new heaters contained 304N SS tubes. In one of the new heaters, an unknown localized contaminant caused a single tube leak within the first year. This single leak went undetected until several surrounding tubes were lost due to impingement from the initial leak. And even the conservatively sized normal and emergency drains were overwhelmed, causing the heater to trip on high level. III. CAPABILITY OF SMART LEVEL CONTROLS. A. There are three known possibilities that would cause high drain-flow conditions in a feedwater heater. 1. High Unit Load. 2. The upstream feedwater heater is out of service. 3. A tube leak. B. Traditional Local level controls can sense high flow conditions, but cannot tell why. Most systems will alarm the opening of the emergency drain valve, but by that time, the collateral tube damage is usually severe. “Smart” Level Controls have the capability to distinguish between these conditions, thus allowing it to give early notification of a tube leak, before collateral damage becomes severe.
A Synthetical Numerical Model for Evaluating the Reliability of Turbine Blade
Authors: Xie Yonghui , Zhang Di
Published: March 2009

Reliability of turbines is very important for power plants, and the most common blade failure normally result from forced vibration which lead to fatigue failure of blades. In this study, a synthetical numerical model has been developed to obtain more precise evaluation of the reliability of blades. At first, the model used to analyze the dynamic stress of steam turbine blades is investigated, base on the results of dynamic stress analysis, a model to evaluate the fatigue life of turbine blade has been developed, many factors such as manufacturing technology of blades and erosion operating environment are considered to get more accurate results for the fatigue life prediction of blades. At last, a 323 mm blade in a 75MW steam turbine is analyzed by the model developed in this paper, it is shown clearly that the model can provide some significant data to evaluate the reliability of blade.
Utility Perspectives on Opportunity Fuels
Authors: Letheby Kirby
Published: March 2009

Use of opportunity fuels can provide cost-effective business deals for utilities. Successful use of these fuels is based on meeting fuel supply needs of the utility. These needs are specific to the particular power plant under consideration and can present significant challenges. Plant needs can be determined through an evaluation process based on a common set of fuel supply requirements. Results of this evaluation identify what is required for a successful fuel-supply business deal. The cost-benefits from this evaluation process are helpful in determining if the opportunity fuel will support a win-win business deal between the fuel supplier and the fuel user. This paper presents a framework for this evaluation process followed by case study reviews. This evaluation process can be helpful to fuel suppliers in understanding how to meet power plant fuel-supply needs and to power plant operators in clearly defining the needs that opportunity fuel suppliers must meet.
Pipeline Integrity: Enhanced Decision Support With Spatial Data
Authors: Porter Todd R. , Martin Monty R. , Dean Alan
Published: March 2009

The Pipeline industry is realizing the significant value that GIS adds to their integrity management programs. Programs are under development and refinement to improve the safety, efficiency, and profitability of this energy transportation infrastructure through effective data integration, analysis, and decision support methods. Case studies will be presented, showing such an implementation, using comprehensive In Line Inspection (ILI) data, Direct Assessment, and other complementary data sources for a large regional gas transmission system and liquid pipelines, complete with experience, benefits and examples.
Long-Term Testing of Trenchless Pipe Liners
Authors: Barbero Ever , Rangarajan Shalini
Published: March 2009

Due to increasing costs and inconveniences in replacing deteriorated sewer pipelines by conventional excavation methods, the trenchless or ‘no-dig’ technology is being extensively used. In trenchless technology, a polymer or reinforced polymer is applied to the inside of the deteriorated host pipe to prevent ground water from seeping into the sewer pipelines. In this research, a testing method was developed to determine the long-term creep behavior of encased polymer liners used in sewer rehabilitation. Short-term tests, following the ASTM D790 procedure, were conducted on pipe liner samples to determine the initial elastic modulus and compare it to the elastic modulus obtained from long-term testing of the encased liner. Long-term tests were conducted on 6 ft. lengths, 12 in diameter polymer liner samples encased in steel pipes. Fabrication service was provided by the industries participating in the research. The thicknesses of the polymer liners were selected according to the typical use of each product in the field. Three samples each of five liner materials were tested under constant external hydrostatic pressure to find their long-term structural properties and to present creep-buckling models. A pressure regulator, pressure transducer, and several pressure gages at different points in the water line were used to maintain constant hydraulic pressure in the gap between the steel host and the polymer liner. A novel method was developed for sealing the ends of the encased liner samples for testing. The long-term creep data was collected with strain gages bonded along the inner circumference of the liner and connected to a Data Acquisition System (DAS). The temperature of the liners was monitored continuously with the use of a thermocouple. The strain data collected from the DAS was compensated for differences in temperature throughout the period of testing, initial deformation, and coefficient of thermal expansion. Several viscoelastic models were investigated in order to fit the data. The data is used to predict the long-term modulus used in design.
Use of Stable Isotope Ratios to Determine the Origin of Coke Formed in Gas Turbines
Authors: Stehmeier Lester , Magyar Brad , Muehlenbachs Karlis , Lang Xiaosu , Dalai Ajay
Published: March 2009

Coke deposits can form in compression equipment on natural gas transmission lines. These deposits are a result of incomplete combustion due to poor fuel gas quality or incorrect equipment design and/or operation. There is an isotopic “signature” which is carried over from the fuel gas into the coke if incomplete combustion occurs, allowing the origin of the coke deposit to be identified. The use of a continuous flow gas chromatograph isotope ratio mass spectrometer (GC/IRMS) provides a convenient method for determining the isotopic composition of the components in the fuel gas. These ratios can then be used to identify if a correlation exists with the 13C/12C ratio of the coke sample. Previous projects in 1999 and 2000 demonstrated that the coke deposits found within gas turbines could be closely related to the incomplete combustion of the fuel gas. One outcome of that work was determining the value for having a good understanding of stable isotope signatures for gas entering the pipeline system. In 2000, fuel gas samples were obtained from various areas in the Alberta TransCanada collection system, their isotope ratios were measured and then used to produce coke. This work substantiated previous project work, reinforcing the isotopic relationship between coke and the source material. Current work is to produce a model to quantitatively relate the various components of the source material to coke deposits. This model could then be used as a tool to enhance the performance of the gas turbines. Detailed investigation into the sensitivity of stable carbon isotope measurements for identifying the source of coke deposits for a complete range of TransCanada fuel gas mixtures is presented.
Effect of Prestrain on Tensile and Fracture Toughness Properties of Line Pipes
Authors: Fukuda Naoki , Hagiwara Naoto , Masuda Tomoki
Published: March 2009

To investigate the mechanical properties of pipeline subjected to plastic deformation, tensile tests and crack-tip-opening displacement (CTOD) tests were conducted on X60, X65 and X80 line pipe steels with uniaxial tensile or compressive prestrain, εpr. The tensile tests revealed that the Bauschinger effect and work hardening were dependent on the yield-to-tensile ratio (Y/T) of the steels; the change in yield stress due to prestrain linearly depended on the Y/T of the base metal. A critical CTOD for crack initiation decreased with increasing |εpr|.Compressive prestrain had a larger effect on the reduction of the critical CTOD than tensile prestrain. The reduction in the critical CTOD due to tensile prestrain was predictable with a simplified theoretical model employing a critical fracture strain of the base metal.
Metallurgical and Mechanical Features of API 5L X65 Pipeline Steel Weldment
Authors: Ju Jang-Bog , Lee Jung-Suk , Jang Jae-Il , Kim Woo-Sik , Kwon Dongil
Published: March 2009

Substantial differences amongst metallurgical and mechanical properties of base metal (BM), weld metal (WM) and heat-affected zone (HAZ) occur in general in welded steel structures It is common practice in various engineering structures to evaluate the fracture performance of welded structures by mechanical testing. Especially, the HAZ of steel welded joints shows a gradient of microstructure and mechanical properties from the fusion line to the unaffected base metal. This study is concerned with the effects of metallurgical and mechanical factors on the fracture performance of API 5L X65 pipeline steel weldments, as they are generally used for main natural gas transmission pipelines in Korea. First of all, we investigated the microscopic and macroscopic fracture behavior of the various micro-zones within the HAZ from the viewpoint of metallurgical factors. The effects of mechanical factors such as welding residual stress in steel weldment and strength mismatch between BM and WM, particularly in high strength steel weldments, are also analyzed. Therefore, the fracture performance of API 5L X65 pipeline steel weldment was mainly dependent on the change of macrostructure and its distribution in the welded joints.
Bayesian Estimates of Measurement Error for In-Line Inspection and Field Tools
Authors: Worthingham Robert , Morrison Tom , Mangat N. S. , Desjardins Guy
Published: March 2009

Knowledge of the measurement errors of an in-line inspection tool and field tool are important (i) for determining the corrosion feature severity and the probability of failure of the pipeline due to that corrosion feature, (ii) for verifying the tool vendors claimed accuracy, (iii) as a component of the tools development program, (iv) as a reference for other inspection tools and (v) for probability of corrosion/crack detection assessments. When in-line inspection tool reporting is used in site specific probability of failure analyses or growth modelling applications, the measurement error of the tool plays a significant role in determining the distributions of penetration and rupture pressure at the time of inspection, or any time in the future. Often, the in-line inspection tools are compared with data obtained from a reference (field) tool which is usually assumed to be perfect, but in reality no tool is perfect. In the late 1940’s a procedure was developed that decomposes the total scatter between tools being compared and assigns an appropriate scatter or measurement error to each tool individually. The procedure is based on a suite of assumptions, which sometimes fail. The typical result is an estimate of measurement error that is negative, similar to a sums of squares estimate in an analysis of variance being negative, which is clearly wrong and unacceptable. Late researchers have suggested methods that overcome this difficulty. These estimators also suffer from certain limitations. In this paper a Bayesian methodology that can overcome some of these recognized limitations is presented.
Probabilistic Fracture Analysis of Pipelines
Authors: Kariyawasam Shahani , Stephens Mark , Sloterdijk Wytze
Published: March 2009

Many pipelines were built before the industry developed material specifications for fracture control. For these older pipelines an essential first step in fracture control is to estimate the existing likelihood of fracture initiation and propagation. It is also desirable for operators to know the size of defects the pipeline can tolerate without causing pipeline fracture. This paper describes a methodology developed for the probabilistic characterization of the fracture initiation and propagation susceptibility of older pipeline segments, made from line pipe exhibiting (by today’s standards) low to moderate strength and low notch toughness. It is applicable to ductile, brittle and mixed-mode fracture behaviour. A probabilistic analysis approach is ideally suited to the problem since it offers a way to quantitatively address both the inherent variability in the mechanical properties of line pipe and the uncertainties associated with the various models currently available to determine the conditions necessary to cause crack initiation or to force crack arrest. The method described addresses both of these forms of uncertainty, and also reflects the added uncertainty inherent in trying to estimate material properties for existing lines from small samples of data.
Development of an Oxygen “Metabolizer” to Control Oxygen Levels in the Closed Cabin of Submarine Rescue Vehicles
Authors: Nuckols M. L. , VanZandt K. W.
Published: March 2009

The U.S. Navy is committed to maintaining the capability of rescuing survivors from a disabled submarine, including situations where the disabled submarine becomes internally pressurized due to flooding, leakage of compressed gas supplies, or through use of auxiliary breathing systems. Efficient submarine rescue requires that pressurized crewmembers be decompressed more rapidly than current decompression procedures allow when using air. The Navy Experimental Diving Unit in Panama City, FL has shown that crew decompression can be accelerated significantly by pre-breathing oxygen. Unfortunately, such oxygen pre-breathing can result in oxygen buildup in the cabin atmospheres of the submarine, and/or rescue chamber through leakage around the face seal of the oxygen masks. High levels of oxygen can create hazardous conditions within the cabin atmosphere due to fire potential and/or oxygen toxicity concerns. This paper addresses the concept development of an oxygen “metabolizer” using a hydrogen catalytic reactor to consume excess oxygen within the closed cabin atmosphere of a rescue vehicle. Such a catalytic reactor has also been shown to give an effective method of reducing the level of oxygen in diver breath heating and diver whole-body heating systems.
Bifurcation of Eigenvalues of Nonselfadjoint Differential Operators in Nonconservative Stability Problems
Authors: Kirillov Oleg N. , Seyranian Alexander P.
Published: March 2009

In the present paper eigenvalue problems for non-selfadjoint linear differential operators smoothly dependent on a vector of real parameters are considered. Bifurcation of eigenvalues along smooth curves in the parameter space is studied. The case of multipleeigen value with Keldysh chain of arbitrary length is considered. Explicit expressions describing bifurcation of eigen-values are found. The obtained formulae use eigenfunctions and associated functions of the adjoint eigenvalue problems as well as the derivatives of the differential operator taken at the initial point of the parameter space. These results are important for the stability theory, sensitivity analysis and structural optimization. As a mechanical application the extended Beck’s problem of stability of an elastic column under action of potential force and tangential follower force is considered and discussed in detail.
Research on Applicability of New Materials to Marine Structures in Tropical Climates: Specimens Exposed for 1 Year
Authors: Tomosawa Fuminori , Tsujikawa Shigeo , Nakatsuji Teruyuki , Yonemaru Keisuke , Saka Koji , Kawaguchi Hiroyasu
Published: March 2009

This study aims to investigate the applicability of newly developed structural materials, which are lightweight and highly durable, to marine structures from the aspect of reducing their life-cycle cost. Since corrosion is primarily the determining factor of the service life of marine structures, exposure tests have been conducted in this study with the focus on corrosion resistance of new structural materials. Twenty-one new materials have been exposed to the environment at three sites: the tropical island Okinotori-shima and subtropical island Miyako-jima, both in Japan, and a hygro-thermostatic room in a laboratory. These experiments started in 1999 as five-year exposure tests. The authors have reported on the selection of potential new structural materials for marine structures (six nonferrous metals, eight steels, four composite materials, and three rope materials), outline of exposure tests, and results of initial performance tests on these materials. As of October 2001, specimens at an age of 2 years were retrieved and are now being examined. This paper reports on the findings obtained after the publication of the previous paper, including the observation and test results of specimens retrieved in 2000 at an age of 1 year. After publishing the previous paper on the ongoing tests, tension tests on unjointed and jointed specimens and SEM observation of corrosion specimens were conducted. Some of the steels exhibited severe corrosion, as well as significant strength losses. Specimens other than those began to exhibit tendencies towards strength changes depending on the material type and specimen type (unjointed/jointed), though not very evident. SEM observation of corroded specimens revealed differences in the state of corrosion among materials.
Drill Pipe Fatigue Analysis: Full Size Apparatus and Coupon Tests
Authors: Ribeiro Pla´cido Joa˜o Carlos , Miscow Guilherme F. , de Miranda Paulo E. V. , Netto Theodoro A.
Published: March 2009

Drill pipe fatigue damage occurs under cyclic loading conditions due to, for instance, rotation in curved sections of the well. Failures caused by crack nucleation and propagation are one of the highest risks to the structural integrity of these pipes. Usually, failure mechanisms develop in the transition region of the tool joint. Several mechanical and metallurgical factors affect the fatigue life of drill pipes. The former are mainly geometric discontinuities such as transition zones, pits and slip marks. The latter are related to the size and distribution of crystalline grains, phases and second phase particles (inclusions). In this study, the roles played by both factors in the fatigue life of drill pipes are studied through an extensive experimental test program. To this end, a fatigue simulator was designed and built to test full-scale drill pipes under rotating cyclic bending and constant tension loading. Additionally, the fundamental fatigue mechanisms are investigated via laboratory tests in small-scale coupons. These tests were performed in an opto-mechanical fatigue apparatus that was specially designed to perform in-situ real time monitoring surface analysis during the experiments.
Optimality and Acceptance Criteria in Offshore Design
Authors: Ku¨bler Oliver , Faber Michael Havbro
Published: March 2009

The optimal design of offshore structures is formulated as a decision theoretical problem. The objective is to maximize the net present value of the service life benefit. The general optimization problem is simplified by taking into account the cost impacts of only one possible reconstruction of the structure. The analytical solution to this problem has been derived for the case, where failure events follow a stationary Poisson process. The service life benefit is formulated in terms of the production profile, the design and construction costs, the costs of failure and the costs of reconstruction. In order to assess the effect of potential loss of lives, the costs of fatalities are included applying the concept of the Imp lied Costs of Averting a Fatality (ICAF). The suggested approach to optimal design, which can be applied for any type of offshore structure, is exemplified considering the special case of steel structures. Here it is standard to represent the ultimate structural capacity in terms of the Reserve Strength Ratio (RSR). For the purpose of illustration, the relation between material usage and RSR valid for monopod structures is applied. Optimal RSR’s and annual failure rates are assessed for both manned and un-manned structures covering a wide range of different realistic ratios between the potential income and costs of construction, failure and re construction costs.