bluuebunny/crossref_metadata_2025 huggingface dataset:
Acquisition of Equipment and Services for Transporting SNF and HLW to the Federal Repository
Authors: Lake William H. , Larson Ned , Slater-Thompson Nancy , Valenzano Michael
Published: August 2008

The Department of Energy, Office of Civilian Radioactive Waste Management expects to begin transporting spent nuclear fuel and high-level radioactive waste to the federal repository being developed at Yucca Mountain, Nevada, when it begins operations in 2010. A review of past transport acquisition activities is given. The strategy, and approach used to acquire private sector supplied equipment and services for the necessary transport activities are described and discussed.
Technology Development to Support OCRWM Transportation Activities
Authors: Lake William H. , Slater-Thompson Nancy , Larson Ned , Oshinowo Franchone
Published: August 2008

Technology development activities are being conducted by the Department of Energy, Office of Civilian Radioactive Waste Management to support spent nuclear fuel and high-level radioactive waste transport to the federal repository at Yucca Mountain, Nevada in 2010. The paper discusses the motivation for pursuing transport technologies for a private sector operated transportation program, and describes some of the current technologies being pursued.
Spent Nuclear Fuel Structural Response When Subject to an End Impact Accident
Authors: Adkins Harold E. , Koeppel Brian J. , Tang David T.
Published: August 2008

The U.S. Nuclear Regulatory Commission (USNRC) is tasked with licensing safe spent fuel storage and transportation systems. A subset of this responsibility is to investigate and understand the structural performance of these systems. In a joint effort between staff at the Pacific Northwest National Laboratory (PNNL) and the USNRC, computational studies were performed to predict the structural response of spent nuclear fuel when subject to an end impact accident. In this study the structural performance of a typical pressurized water reactor fuel assembly is evaluated using the ANSYS®/LS-DYNA® finite element analysis code.
Detection of Corrosion of Insulated Piping Using SH Angle Probe
Authors: Kikuchi Tsutomu , Yotsutsuji Mitoshi , Yokono Yoshikazu , Nitta Kaoru , Takagi Yasushi
Published: August 2008

One of the serious problems regarding insulated piping in petroleum and petrochemical plants is external surface corrosion. In general, visual inspection after removing insulation is carried out to detect corrosion. However, removing insulation is uneconomical, namely high cost, and time consuming processes are necessary such as setting up a scaffold. Ultrasonic guided wave technique has potential possibility to detect corrosion of long piping and has been recently investigated regarding its propagation characteristics. In this study, guided wave generated by horizontally polarized shear (SH) wave is applied to detect corrosion of insulated piping ranging from 1B to 3B. The reason why we select SH wave is that it has an advantage of being insensitive to internal fluid in piping. Through this study it is clear that SH guided wave is applicable to small diameter piping because sound beam of SH wave propagates along the longitudinal direction without circumferential extent. Accordingly local corrosion can be detected using SH guided wave technique.
Application of Advanced Ultrasonic Technology to Measure Internal Deposit Thickness for Boiler Waterwall Tubes in Thermal Power Plants
Authors: Imaizumi Yukio , Sueyoshi Mitsuhiro , Furue Toshihiko , Seto Shizuo , Nagai Tatsuyuki , Yamamoto Hiroshi , Hara Kevin
Published: August 2008

Recently, it was required to investigate the distribution of scale deposits on the inner surface of boiler waterwall tubes in a thermal power plant, because the excess scale deposits are the major concerns causing a decline in thermal efficiency and damage by overheating. To avoid these problems tube sampling and metallurgical examinations are carried out and appropriate periods of chemical cleaning are determined. Under the circumstance non-destructive methods to measure the thickness of scale deposits have been needed. The ultrasonic method can be used to estimate the thickness of scale deposits by using the time difference from interface signal between base metal and deposit to the back surface signal of deposits, when the thickness is 100 micrometers or more. However, the thickness can’t be estimated when the thickness is up to 100 micrometers because these two signals are overlapped and superimposed. In this study advanced measurement technology by analyzing the superimposed waveform was developed. As the results of experiments, the thickness of scale deposits can be estimated with accuracy of 10 micrometers. Also this technology can be applied to evaluate the effect of chemical cleaning.
Development of a Miniature Portable X-Ray Instrument for the Non-Destructive Measurement of Stresses
Authors: Rund C. O.
Published: August 2008

Residual surface stresses have been shown to play a critical role in the failure of metallic components through fatigue, stress corrosion cracking, and corrosion fatigue. A method of measuring these residual stresses remotely and nondestructively would improve the ability to assess the potential failure susceptibility of components in service.
Ultrasonic Stress Measurement in Welded Component by Using Lcr Waves: Analysis of the Microstructure Effect
Authors: Walaszek H. , Hoblos J. , Bourse G. , Robin C. , Bouteille P. , Lieurade H. P.
Published: August 2008

Welding, which is a largely used process in the mechanical manufacturing, is one of the causes of high-level residual stresses. The level of residual stresses has a great importance for the life time of welded components used in mechanical engineering industry. The ultrasonic technique may be used to determine the residual stresses. The technique is based on the acoustoelastic effect, which refers to the change in the velocity of ultrasonic waves propagating in strained solids. Previous studies were carried out to evaluate residual stresses by using ultrasonic methods, but they do not enable to exactly determine the stress values in the heat-affected zone (HAZ) and the melted zone (MZ). This paper describes the experimental procedure of ultrasonic stress measurements applied to welded manufactured joints for different steel grades such high elastic limit material. It is noticeable that, to take into account of microstructure influence on ultrasonic behavior of the weld, the measurement were calibrated on samples machined in the melted zone and in parent metal. The results obtained by the ultrasonic Lcr waves technique were compared with those obtained by “reference” techniques such as hole-drilling. This work confirms the possibility of evaluating the residual stresses induced by welding using the ultrasonic method, and shows improvements obtained in taking into account of metal microstructure for evaluating stresses in the welds.
Evaluation of Fatigue Damage in Coarse-Grained Aluminum With Scanning X-Ray Energy Dispersive Diffraction Microscope
Authors: Hosokawa Yoshinori , Tanabe Hirotaka , Miyoshi Yoshio , Takamatsu Tohru , Oborii Kenichi
Published: August 2008

Based on the Berg-Barrett method, Scanning Energy Dispersive X-ray Diffraction Microscopy (SEDXDM) has been developed for nondestructively evaluating both the surface and subsurface of poly-crystallized materials. The SEDXDM includes an X-ray source generating continuous X-ray spectrum as a key component to form a highly resolved 2-D horizontal cross-sectional digital image. This article presents the evaluation of the fatigue damage (e.g., slip line and slip band caused by fatigue deformation) of the coarse-grained aluminum, which is made by means of annealing and has been repeatedly bent to generate the stress and make the slope of the stress created in the thickness direction of the plate specimen, under fully reversed anti-plane bending condition with the SEDXDM.
Characterization of SH Wave Electromagnetic Acoustic Transducer (EMAT) at Elevated Temperature
Authors: Xu Yang , Tagawa Akihiro , Ueda Masashi , Yamashita Takuya , Ohtsuka Yusuke , Osafune Kazunori , Nishikawa Masahiro
Published: August 2008

The in service inspection (ISI) of MONJU fast breeder reactor vessel is performed in a severe environment at elevated temperature (about 200 °C ) and high-level radiation field (about 10Sv/h). Liquid sodium is used as the coolant of MONJU reactor. A horizontally polarized shear (SH) wave electromagnetic acoustic transducer (EMAT) is used to perform the volumetric inspection of the MONJU reactor vessel. In this paper, the magnetic flux density and the sound pressure distributions for the SH wave EMAT with a so-called Halbach magnet structure are analyzed from room temperature up to 240°C. The magnetic flux density and the sound pressure of the EMAT decrease with the increase of temperature. At 200°C, the relative reduction of the peak magnetic flux density and the relative thermal demagnetization at liftoff distance 0.5mm are less than 9% and 2%, respectively. This thermal demagnetization can be understood by analyzing the distribution of the permeance coefficient. As a result, the Halbach magnet structure can be used at elevated temperatures without large performance reductions as compared to its performance at room temperature. The Halbach EMAT will demonstrate good performance not only at room temperature but also at high temperature up to 240°C. This new structure EMAT is suitable for MONJU reactor vessel ISI.
Influence of Ultrasonic Incident Angle and Defect Detection Sensitivity by Cast Stainless Steel Structure
Authors: Kurozumi Yasuo
Published: August 2008

It is well known that ultrasonic waves are affected strongly by macro-structures in cast stainless steel, as in the primary pipe or other components in pressurized water reactors (PWRs). In this work, ultrasonic refractive angles and defect detection sensitivities are investigated at different incident angles to cast stainless steel. The aims of the investigation are to clarify the transmission of ultrasonic waves in cast stainless steel and to contribute to the transducer design. The results are that ultrasonic refractive angles in cast stainless steel shift towards the 45-degree direction with respect to the direction of dendritic structures by 11.8 degrees at the maximum and that the sensitivity of transducer for inner surface breaking cracks increases with decreasing incident angle. However, in an ultrasonic inspection of actual welds at smaller incident angles, a trade-off occurs between increased defect detection sensitivity and decreased defect discrimination capability due to intense false signals produced by non-defective features.
Fatigue Damage Evaluation in CFRP Woven Fabric Composites Through Dynamic Modulus Measurements
Authors: Kasano Hideaki , Hasegawa Osamu , Miyasaka Chiaki
Published: August 2008

Advanced fiber reinforced composite materials offer substantial advantages over metallic materials for the structural applications subjected to fatigue loading. With the increasing use of these composites, it is required to understand their mechanical response to cyclic loading [1–4]. Our major concern in this work is to macroscopically evaluate the damage development in composites during fatigue loading. For this purpose, we examine what effect the fatigue damage may have on the material properties and how they can be related mathematically to each other. In general, as the damage initiates in composite materials and grows during cyclic loading, material properties such as modulus, residual strength and strain would vary and, in many cases, they may be significantly reduced because of the progressive accumulation of cracks. Therefore, the damage can be characterized by the change in material properties, which is expected to be available for non-destructive evaluation of the fatigue damage development in composites. Here, the tensiontension fatigue tests are firstly conducted on the plain woven fabric carbon fiber composites for different loading levels. In the fatigue tests, the dynamic elastic moduli are measured on real-time, which will decrease with an increasing number of cycles due to the degradation of stiffness. Then, the damage fimction presenting the damage development during fatigue loading is determined from the dynamic elastic moduli thus obtained, from which the damage function is formulated in terms of a number of cycles and an applied loading level. Finally, the damage function is shown to be applied for predicting the remaining fifetime of the CFRP composites subjected to two-stress level fatigue loading.
The Simulation of the Flow Generated by the Interaction Between an Inlet and a Cross-Flow
Authors: Adun Janyalertadun , Holdo̸ Arne E. , Wakes S. J.
Published: August 2008

The flow generated by the interaction between an inlet and a cross-flow are frequently found in many engineering and industry application, example is at the inlet of air duct in ventilation system. The simulations were using the experimental data to be the reference.1,2 The simulation was investigated using the Large Eddy Simulation (LES) where the small scales of turbulence are modelled by following the Smagorinsky idea’s.3 Three different inflow boundary conditions, steady uniform, steady profile and turbulent, were tested. The results downstream of the intake are very sensitive to the turbulent inflow compared to the steady inflow when the mesh in coarse. In particular the turbulent inflow condition case shows the streamwise vortices downstream whist the steady inlet does not show these vortices. These vortices were not mentioned in the experiment results. The vortices can only be observed for the turbulent inlet conditions results in a coarse mesh. This implies that when the meshes are too big, the numerical viscosity could be significant. An artificial turbulent condition needed to be applied to show these turbulence phenomena. Whilst when the mesh resolution was increased, the smaller scale of flow can be solved and it can show these turbulent phenomena by itself.
Micro Fluidics Using Novel Materials
Authors: Tracey M. C. , Johnston I. D. , Tan C. K. L. , Davis J. B.
Published: August 2008

We report two novel microfluidic devices fabricated from PDMS (polydimethylsiloxane). Such devices are indicative of the increasing migration of microfluidics to materials distinct from those of the mainstream Silicon MEMS industry. Specifically, plastics fabrication techniques and materials such as SU8 photostructurable epoxy and microcasting, which are employed in these examples, are proving particularly topical and are discussed here. The devices reported consist of PDMS-glass-piezoelectric hybrids exploiting the compliant nature of elastomer substrates to yield valuable functionality. The first device is a micropump employing novel, non-sealing valves and pumping 300 microlitres per minute and developing a maximum pressure of 6kPa. The second reported device is a micromixer employing temporal interleaving of samples via PDMS-glass microvalves in order to mix effectively within the laminar, microfluidic flow regime.
Modeling of a Gas Leakage Including Droplet Transport
Authors: Polanco G. , Holdo̸ A. E.
Published: August 2008

Safety assessment of compressed gas storage and pipeline facilities has to consider accidental leaks to the atmosphere. A major concern for modelling of such accidental leaks is the phase change behaviour of the compressed (liquid) gas. The present study assumes that droplets of the liquid gas are present in the gas leak jet. The effect of the droplet concentration and diameter on the behaviour on the jet is studied using Computational Fluid Dynamics (CFD). The impact of these variables on local gas distribution is analysed and discussed.
Computational Fluid Dynamic Simulation of High Aspect Ratio Cross-Sectional Orifice Jets: Shape of the Gasket on the Internal Flow
Authors: Wakes Sarah J.
Published: August 2008

Improved computing power has increased the capacity of numerical modellers to simulate real-life situations with the expectation that results will be useable and accurate. It is easy when modelling physically large geometries to over simplify aspects of the model, usually because of mesh restrictions, that could be to the detriment of the results. For many years Computational Fluid Dynamics has been used to simulate leaks of hydrocarbons with the production areas of offshore superstructures, [1, 2]. Many simplifications are required, one of which is modelling these leaks as axisymmetric jets. Previous work, [3, 4] has shown that this is not a good simplification and could have serious safety implications. A more accurate model of the jet is needed for the full consequences of a gas leak to be ascertained. Having established that a leak from a flange or crack in a pipe needs to be modelled as a high aspect ratio cross-sectional orifice jet there are also other considerations. Work on the turbulence model and inlet conditions that are best suited for these simulations has been done, [5, 6]. This paper investigates the flow within the pipe and up through the gasket before release into the air as a jet. Different idealised shapes of gaskets are used and the flow at the jet exit are investigated. It is hoped that a range of conditions can be established that set criteria for such modelling in the future.
Eulerian-Lagrangian Coupling in Finite Element Calculations With Applications to Machining
Authors: Benson David J. , Okazawa Shigenobu
Published: August 2008

Multi-material Eulerian finite element methods are attractive for problems in solid mechanics where new free surfaces are created, e.g., the formation of chips in machining. One weakness associated with the Eulerian finite element formulation, however, is the interaction of materials at the contact interface. The standard mixture theories effectively bond the materials together, and prohibit the relative slip between the materials that is crucial for an accurate machining simulation. In this paper, we compare the results of a machining calculation performed using an Eulerian formulation with a contact mixture theory and a coupled Eulerian-Lagrangian calculation, where the workpiece is Eulerian, and the tool is Lagrangian.
A 3D Variational BEM Formulation for Fluid-Structure Interaction in Viscous Compressible Flow
Authors: Erchiqui F. , Gakwaya A.
Published: August 2008

This paper is aimed at presenting recent advances in modeling and simulation of vibrating structures in presence of external as well as of internal fluid flows using methods based on symmetric variational BEM formulation coupled with the FE. The structural weak form is coupled with a novel boundary element variational formulation of a compressible viscous fluid. The proposed formulation has distinct advantages: (i) over the classical FE, it avoids the discretisation of the fluid domain; (ii) over the collocation BEM formulation, it avoids the explicit calculation of the finite part of hypersingular integrals. Also, the discretisation, by the boundary finite element procedure, of the resulting mixed variational functional leads to a symmetric algebraic system. A computer code based on these concepts has been developed and applied to calculate 3D vibroacoustic behavior of various coupled mechanical systems.
Simulation of Vibroacoustic Problem Using Coupled FE/FE Formulation and Modal Analysis
Authors: Alia Ahlem
Published: August 2008

Vibroacoustic consists of the interaction between elastic and acoustic waves. This interaction causes the acoustic pressure to exert a force to the structure and the structural motion produces an effective fluid load. Hence, studying vibroacoustic problems requires that both elastic structure and fluid to be modeled. In this paper, a simple vibroacoustic problem is modeled by a coupled FE/FE modal analysis method in which a lumped mass representation is considered. The numerical results are represented for an elastic plate backed cavity. In this method, the coupling system is projected on some structural modes in vacuum and some rigid cavity modes. The obtained system is put in a diagonal form by solving left and right eigenvalues problem. Some results are presented to illustrate the effect of the modal analysis and the lumped mass formulation. Some numerical results were compared to analytical solutions.
Measurement of Flow Induced Rotor Oscillations in a Single-Blade Centrifugal Pump
Authors: Benra Friedrich-Karl , Dohmen Hans Josef , Schneider Oliver
Published: August 2008

The composition of sewage water with partially large portions of fibers and solids requires a special impeller geometry, in order to avoid operational disturbances of the pump by clogging. Therefore the almost exclusively used single stage machines particularly are equipped with single-blade impellers. The rotation of the impeller in the pump casing produces a strongly uneven pressure field along the perimeter of the casing. The resulting periodically unsteady flow forces affect the impeller and produce radial deflections of the pump shaft which can be recognized as vibrations at the bearing blocks or at the pump casing [1]. In this contribution the experimental investigation of the dynamic behavior of a pump rotor under the influence of the flow forces is described. To verify calculated results performed earlier a lot of measurements have been carried out at several speeds of rotation and at different volume flow rates. The pump which before was investigated numerical had been equipped with several sensors. The deflections of the pump rotor were measured with two proximity sensors and compared to the computed amounts. Measurements of the static pressure in the casing gave the connection between the rotor oscillations and the pressure fluctuations produced by the single-blade impeller. The simultaneous measurements of the vibration velocities and accelerations at the pump casing showed the effects of the transient hydrodynamic stimulation forces.
Numerical Simulation of Sheet Metal Forming Using Underwater Shock Wave
Authors: Iyama Hirofumi , Hinata Takeshi , Itoh Shigeru
Published: August 2008

In recent years, aluminum alloy is being used to fabricate car bodies. #5000’s or 6000’s aluminum alloy series is widely employed. However, the sheet metal forming of these materials by the static method, such as the hydro bulge forming and general punching, is very difficult, because the formability characteristics are limited when compared to majority of automobile steels. Hence, the choice of explosive forming is considered for forming these aluminum alloys. Te elongation of aluminum alloy by explosive forming is compared with that obtained by punching. The amount of deformation of aluminum alloy by the explosive forming is found to be larger. In addition, a theoretical elucidation is also done. FDM scheme was employed to solve the numerical simulation. In this simulation the detonation process of the explosive, propagation process and deformation process of aluminum alloy were conducted.
Preliminary Study on the Fragility of Building Structures in Taiwan
Authors: Liao Wen-I. , Lee Bor-Han , Loh Chin-Hsiung
Published: August 2008

This paper describes procedures of fragility analysis for building structures in earthquake loss estimation methodology in Taiwan (Haz-Taiwan system). The main objective of this paper is to define the building classification, relative damage states and provide the fragility functions for the general building structures in Taiwan that by utilize the available data. First, the available classes of the building structures in Taiwan are reviewed and a classification based on the available data to be implemented in Haz-Taiwan system is proposed. Second, the description of failure mechanisms and performance criteria based on the collected experimental data for different damage states that adopted in this research are proposed. Third, the theoretical methodology of the fragility analysis for the adopted building classes is introduced. Parameters for describing the fragility functions for each class are also generated and shown in the Table.
Solutions to Design Displacements of Base Isolation Code in Taiwan
Authors: Chen Bo-Jen , Tsai C. S. , Chen Wen-Shin , Chiang Tsu-Cheng
Published: August 2008

Base isolation is a new seismic design concept which lessens the seismic responses of the superstructure during earthquake ground motions. It has been proven that base isolators possess good earthquake-proof benefits through theoretical, experimental and recorded data demonstrations. However, it is a very important issue for engineering professions to easily design the base isolators. The Ministry of the Interior in Taiwan promulgates a series of code provisions for the base isolation technologies after the 921 Chi-Chi earthquake. In this study, we propose new design procedures for the design displacements of elastomeric rubber bearings and friction pendulum systems based on solving the polynomial function of the design displacement. In order to prove the accuracy of the proposed method, we compare the computed results by the proposed design method with those through the traditional iteration design procedure of the design displacement according to the base isolation design code in Taiwan. A good agreement between the proposed design method and the traditional iteration design procedure has been obtained and verified in this study.
Experimental and Analytical Studies of Rocking Mechanics of Unanchored Flat-Bottom Cylindrical Shell Model Tanks
Authors: Taniguchi Tomoyo
Published: August 2008

Employing a few feasible physical quantities of liquid related to the rocking motion of tanks, this paper tries to understand the fundamental dynamics of the rocking motion of tanks. Introducing the effective mass of liquid for rocking motion and for rocking-bulging interaction motions, the equations of motion are derived by analogue of rocking motion between rigid bodies and tanks. Using the exclusive tanks that possess the rigid-doughnuts-shape bottom plate that guarantees the uplift region of the bottom plate and the extent of the effective mass of liquid for rocking motion, the harmonic shaking tests are carried out. The proposed procedures can stepwise trace the base shear and the uplift displacement of the model tanks used herein.
Structural Analysis of High-End Server Computer Frames Under Earthquake Loading
Authors: Canfield Shawn , Notohardjono Budy D.
Published: August 2008

This paper reports the mechanical design, structural analysis, and experimental correlation of bracing concepts for high-end computer servers subjected to loads simulating earthquake conditions. The development and evaluation of these stiffening alternatives follows a step-by-step process of finite element analysis coupled with parallel experimental testing. The numerical model is derived from the simplified CAD geometry of an existing server frame. An analysis of this frame model is subjected to a load environment similar to those endured under actual horizontal table vibration tests. The result of this series of analyses is a design study examining how a range of bracing designs affects the global frame rigidity. This design study builds toward the objective of constructing a verified model of the server frame and components that will lead to a guideline for implementing stiffener designs on high-end server systems.
Low Cost Friction Pendulum-Type Earthquake Isolation Device With Poly-Curvature Suitable for Light-Weight Equipment
Authors: Fujita Satoshi , Kurabayashi Hiroshi , Yamamoto Hiromichi
Published: August 2008

This paper describes the results of the response analysis and the experimental tests on the newly developed earthquake isolation system based on the theory of friction pendulum. In Japan, many types of earthquake isolation device or system have been developed and utilized to protect computers, precision equipments and important works of art from the severe seismic attacks. Although the performance of isolation of the each every one of the systems is sufficient, cost of the system is considered generally higher than the user expected and the system requires enough surrounding space to obtain adequate isolation performance. When applying the isolation device to the objects such as display cabinets in museum, computer server racks, bookshelves in library and vending machines which are generally placed adjacent to the wall, it is desirable to set them as closer to the behind wall as possible without decreasing their performance of isolation very much. The friction pendulum type isolation device with poly-curvature has been developed to satisfy these requirements, and the response analysis and the shake table tests have been carried out to investigate the performance of the system.
Study on the Newly Developed 3-Dimensional Base Isolation System Using a Velocity Reduction Mechanism
Authors: Ito Tomohiro , Fujita Katsuhisa , Ohkubo Takeshi
Published: August 2008

Due to the Hyogo-ken Nambu Earthquake in 1995 and the huge earthquakes which are considered to occur in near future, the raise in the seismic design criteria in the horizontal and vertical excitations has been investigated. According to these trends, many base isolation structures have been developed and constructed. However, the most of these structures are limited to the horizontal base isolation. Therefore, the development of the effective 3-dimentional base isolation system becomes more and more important. The conventional 3-dimentional base isolation systems proposed up to now are insufficient in reducing the vertical natural frequency, otherwise are very complex due to facilitation of the active components. In this study, the dynamic characteristics of a high performance 3-dimentional base isolation system newly developed by the authors are reported. This system employs a velocity reduction system using a gear mechanics which can reduce the vertical natural frequency less than 1Hz while that of the conventional system is around 3Hz. And also this employs friction dampers to suppress the large displacement. Further, this system is facilitated with a rocking-suppression system which can effectively suppress the rocking motion inevitable for 3-dimentional base isolation. The response acceleration, displacement and rocking motion are evaluated by numerical simulations in varying the friction force, the predominant frequency of seismic input waves, the eccentricity of the upper structural mass, etc.. As the results, it is shown that the base isolation system developed here has very effective base isolation characteristics and the rocking suppression effects. And the optimization of the structural parameters is also discussed.
Compressive Stiffness Verification of Stirrup Rubber Bearing
Authors: Chen Bo-Jen , Tsai C. S. , Chiang Tsu-Cheng
Published: August 2008

In recent years, there has been an immense amount of interest in utilizing the rubber bearing system as a practical approach to seismic-resistant design. The stirrup rubber bearing is confined and bonded by stirrup equipments so as to restrict the lateral expansion of the rubbers due to axial load and increase the compression stiffness. Based on two kinematics assumptions that the horizontal plane parallel to the stirrup equipments or rigid bounding steel plates remains plane and the vertical lines become parabolic after loading, the pressure function and compression stiffness for the stirrup rubber bearing are derived. A good agreement between experimental results by the component tests and computational results by the proposed formulae has been obtained.
Piping Service Life Experience in Commercial Nuclear Power Plants: Progress With the OECD Pipe Failure Data Exchange Project
Authors: Lydell Bengt , Mathet Eric , Gott Karen
Published: August 2008

An extension of a 1994–98 R&D project established in 2002 by certain member countries of the Organisation for Economic Cooperation (OECD), the OECD Pipe Failure Data Exchange (OPDE) Project has produced a major database on the piping service experience applicable to commercial nuclear plants. The 3-year project is operated under the umbrella of the OECD Nuclear Energy Agency (NEA) and organizations producing or regulating more than 80% of nuclear energy generation worldwide are contributing data to the OPDE Project. The Project considers pipe failure data including service-induced wall thinning, part through-wall crack, pinhole leak, leak, and rupture/severance (i.e., events involving large leak rates up to and beyond the make-up capacity of engineered safeguards systems). The part through-wall events include degradation in excess of code allowable for pipe wall thinning or crack depth. OPDE also addresses such degradation that could have generic implications regarding the reliability of in-service inspection. At the end of 2003 the OPDE database included approximately 4,400 records on pipe failure affecting ASME Code Class 1 through 3 and non-Code piping. The database also included an additional 450 records on water hammer events where the structural integrity of piping was challenged but did not fail. This paper summarizes the unique data quality considerations that are associated with piping components. The paper also summarizes the database content.
Fatigue Reliability Assessment and Updating With On-Line Nondestructive Inspection for Pressure Vessels
Authors: Chen Guohua , Haldar Achintya
Published: August 2008

Fatigue reliability assessment of pressure vessels is an important challenge to the engineering profession. The challenge is present during the whole life of pressure vessels. The problem is comprehensively studied and is reported in this paper. A fatigue reliability assessment technique is presented first. Nondestructive Inspections are routinely used to maintain the reliability to an acceptable level during the lifetime of a pressure vessel. At present, information from the nondestructive inspections (NDIs) is rarely used for safety evaluation. Even if no crack is detected during an inspection, it provides valuable information that is often overlooked. A reliability updating method is presented to address this weakness in the fatigue reliability evaluation of pressure vessels. The basic reliability method is extended to estimate the updated reliability. Nondestructive inspections are generally conducted at a specified time interval. To facilitate the continuous fatigue reliability evaluation, an on-line intelligent NDI technology is incorporated. The methodology is explained with the aid of an example. It is expected that the fatigue reliability evaluation of pressure vessels will be significantly improved if the proposed method is used.
NRC Review of Time-Limited Aging Analyses for License Renewal Applications
Authors: Medoff James , Chang Kenneth C. , Nguyen Duc , Shah Vikram N.
Published: August 2008

A license renewal applicant of a U.S. nuclear power plant is required to demonstrate that all the time-limited aging analyses (TLAAs) applicable to the facility are valid for the period of extended operation, or have been projected through the expiration of the period of extended operation, or that the effects of aging associated with the TLAAs will be adequately managed during the period of extended operation. Common to license renewal applications are four TLAAs: (1) reactor vessel (RV) neutron embrittlement analyses, (2) fatigue analyses of ASME Section III metal components, (3) environmental qualification analyses of safety-related electrical equipment, and (4) low-cycle fatigue analyses of reactor coolant pump flywheels. The RV neutron embrittlement analyses include the determination of neutron fluence for the RV at the end of the period of extended operation (end-of-extended-license fluence), and evaluation of the following analyses that are based on the end-of-extended-license fluence: drop in Charpy upper-shelf energy, reference temperature for nil-ductility transition, pressure-temperature limits, and BWR vessel circumferential weld examination relief and axial weld failure probability. This paper discusses these four common TLAAs and focuses on the regulatory basis for accepting them as part of the license renewal application; it also discusses the lessons learned from reviewing the license renewal applications.
Lifetime Management of WWER Reactor Pressure Vessels
Authors: Brumovsky Milan
Published: August 2008

Reactor pressure vessels are the most important components of nuclear power plants from safety and economic point of view. Thus, special interest is given to their lifetime management that requires a precious and periodical evaluation of their conditions. In Czech Republic, special program has been prepared for reactor pressure vessels in both nuclear power stations — Dukovany NPP with 4 units of WWER-440 MW and Temelin with 2 units of WWER-1000 MW reactors. This program is based on the following activities: • detailed calculations of real and potential regimes, especially of pressurized thermal shock events, • determination of vessel properties on the basis of testing surveillance specimens from standard, modified and supplementary programs, • calculations of neutron fluences on vessel wall, • measurements of neutron fluences on surveillance specimens and in vessel cavity, • evaluation of all results, evaluation of fluence and material property trends, • recommendations for future reactor pressure vessel operation (potential mitigation measures). The paper describes in detail all these activities and gives examples of their results and final evaluations. Lifetime assessment is based on a “Unified Procedure for Lifetime Assessment of Components and Piping in WWER NPPs (VERLIFE)” using “Master Curve” approach for vessel integrity evaluation [1].
Knowledge Modeling for Asset Management Evaluation
Authors: Bauby Catherine E. , Hai¨k Philippe , Remy Emmanuel , Ricard Benoiˆt
Published: August 2008

The long-term management of a production asset raises several major issues among which rank the technical management of the plant, its economics and the fleet level perspective one has to adopt. Decision-makers are therefore faced with the need to define long term policies (up to the end of asset operation), which take into account multiple criteria including safety (which is paramount) and performance. In this paper we remind the reader of the EDF three-level methodology for asset management. As introduced in PVP 2003, this methodology provides decision-makers with indicators to evaluate the status of a plant. The methodology addresses the component/technical level (how to safely operate daily and invest for the future), the plant level (how to translate technical decisions into plant-wide consequences including economic performance) and the fleet level (how to manage a large number of similar assets). Identifying what might occur to ageing plant components, how operations or maintenance decisions might influence these occurrences and what the consequences of these decisions and events might have on plant operation, is definitely an expert task. In order to gather, preserve, share, maintain and exploit this expert knowledge, we therefore relied on a “knowledge modeling” activity. This activity is used to support the asset management evaluation methodology. We detail the knowledge model — an entity/relation expert description of the plant life-management domain — on which our three-level methodology relies. Lastly, we focus on the software tool that implements this model in order to allow decision-makers to define, analyze and evaluate long-term plant operation and maintenance policies.
ANO-1 Experiences Using Structural Tools During License Renewal Application
Authors: Ahrabli Reza
Published: August 2008

Arkansas Nuclear One, Unit 1 (ANO-1) submitted an application to the Nuclear Regulatory Commission (NRC) to extend its operating license for an additional 20 years on January 31, 2000. NRC regulations governing the license renewal process require the preparation of an Integrated Plant Assessment (IPA) to demonstrate that the effects of aging on systems, structures and components (SSCs) at ANO-1 are adequately managed. ANO participated in the B&W (now Framatome) Owners Group (BWOG) Generic License Renewal Program (GLRP) in developing the B&WOG “Aging Effects for Structures and Structural Components”, commonly referred to the “Structural Tools”. The Structural Tools (Mechanical and Electrical Tools are also available) is a generic evaluation based on material and environments that assist the user in performing an evaluation of aging effects. Using the Tools, considerable time was saved in preparing Aging Management Review Reports (AMRR) since the reviewer did not have to independently research potential causes of aging effects for the materials and environments being reviewed. This paper summarizes the ANO-1 experiences in preparing AMRRs utilizing the Structural Tools.
Robotics in the Nuclear Environment: Inspection and Repairs Inside the Primary Coolant System
Authors: Tortolano Marcel , Guillet Jacques
Published: August 2008

EDF is the French national power generating utility. It has built and operates 58 pressurized water reactor (PWR) nuclear power plants on 19 sites. Of these, thirty-four are 900 megawatt units (the first of which, the Fessenheim NPP, came on line in 1977), twenty are 1300 MW units, and four are 1450 MW units, the latest of which, at the Civaux plant, came on line in 1998. The average age of these nuclear power plants is thus 20 years. They produce close to 85% of the power EDF generates in France. Renewal of the nuclear plants is under study, as are other means of power generation. For the moment, EDF is requesting approval to run its nuclear plants for up to 40 years. Moreover, it has started a major project on the lifetime of PWR reactors, the main objective of which is to extend the authorized lifetime to 60 years. Major requirements for maintaining the current performance of the French nuclear generating facility and reducing the cost per kWh generated include optimization of expenses and reduction of fuel costs. These factors enabled the cost per kWh to be reduced by 13% in 2001. One way to reduce costs involves optimization of maintenance programs and methods. However, increasing the operating lifetime of plants, and the concomitant ageing of equipment and materials, is likely to result in increasing maintenance requirements. For this reason it is important to establish new, more cost-effective maintenance methods in order to keep costs down. Some of these methods make use of robotics. They make it possible for work to be carried out from the inside of circuits, for inspections and even for repair if defects are detected. The results presented here are those of work carried out by the EDF R&D division on behalf of the Nuclear Power Plant Operations (NPPO) division.
Application of Hot Hardness Test to the Evaluation of Creep Damage in Cr-Mo-V Turbine Rotor of Fossil Power Plant
Authors: Sakai Shinsuke , Izumi Satoshi , Murakami Takashi , Nitta Akito , Kusumoto Junichi , Watanabe Yu
Published: August 2008

In residual life evaluation of fossil power plants, improvement of accuracy of creep damage evaluation is extremely important. One of the powerful non-destructive evaluation methods is hardness test. This method is effective because it enables us the on-site evaluation and the results are obtained without laborious work. However, in order to make it more powerful method, improvement of accuracy is inevitable. In this paper, the Vickers hardness test not at ambient but at high temperature is applied to the deteriorated rotor material and the method for the residual life evaluation with high accuracy is newly developed. In the method, creep constitutive law is determined from the results of hot hardness test first. Next, the variation of constitutive law with the creep damage is investigated. Finally, the dependency of exponent of constitutive law on the creep damage is shown and the method to evaluate the creep damage from this dependency will be proposed.
Improvement of Fatigue Strength by Using Cavitating Jet in Air
Authors: Soyama Hitoshi , Macodiyo Dan
Published: August 2008

Cavitation normally causes severe damage in hydraulic machinery such as pumps and valves. However, the cavitation impacts at the bubble collapse can be used to enhance the surface of metallic materials just as the same way as shot peening. In case of peening using cavitation impact, the cavitation is produced by injecting a high-speed water jet in a water-filled chamber. The authors have already demonstrated the fatigue strength improvement of materials using a high-speed water jet in water. Recently the authors succeeded in producing a cavitating jet in air by injecting a high-speed water jet into a low-speed water jet using a concentric nozzle. Cavitating jet in air can be used to peen parts of plant which cannot peened by the water-filled chamber, thereby impeding the initiation and/or the development of cracks. In this study, in order to demonstrate the improvement of fatigue strength of materials using cavitating jet in air, stainless steel (JIS SUS316L) was peened and the residual stress measured using the X-ray diffraction method. The surface residual stress of non-peened and peened specimen was −68 MPa and −350 MPa, respectively. The fatigue strength of the specimen were then investigated using the rotating bending fatigue test, with a stress ratio of R = −1. The fatigue strength of peened specimen by cavitating jet in air improved by 20% compared with nonpeened specimen.
Fretting Fatigue Strength of Nozzle Shaped Structure
Authors: Hayashi Makoto , Ito Takashi
Published: August 2008

In-Core Monitor (ICM) housing of BWR reactor pressure vessel is subjected to the flow induced vibration (FIV). The flow fluctuation takes places in the lower plenum of reactor pressure vessel. It is very much important to evaluate the structural integrity of ICM housing in order to maintain high operating rate. Thus we performed the FIV simulated fatigue test of ICM housing. However, the stress at the weld toe induced by FIV is sufficiently low not to fail. The fatigue endurance limit for the weld root fatigue test specimen with dull taper is 196 MPa. On the while, the fatigue endurance limit for the weld root fatigue test specimen with steep taper is not obtained. When the fatigue test results are approximated by the Stromeyer equation, the fatigue strength for the fatigue life of 109 cycles is estimated as 27 MPa. Finally we performed the fracture mechanics analysis, which indicates that the stress intensity factors for Mode I and II range from 0.1 to 0.2 MPam so that the fatigue crack is not initiated at the weld root by FIV.
KI Evaluation Method on Crack Growth of Bottom Mounted Instrumentation Penetrations in a Reactor Pressure Vessel
Authors: Mukai Masayuki , Yamashita Tetsuo , Chigusa Naoki , Asada Seiji , Kameyama Masashi
Published: August 2008

A method to evaluate a Mode I stress intensity factor KI for bottom mounted instrumentation (BMI) penetrations (nozzles) in a reactor pressure vessel (RPV) has been developed in order to perform the crack growth analysis simply and accurately. As regards the KI evaluation method, the several studies has been reported for a simple pipe with inside surface crack [1][2][3]. However, the study on the structure like the BMI nozzle joined with the vessel head by J-welding, has never been reported. Therefore, KI for BMI nozzles should be evaluated considering the load and the displacement by this interaction. The KI is evaluated simply by multiplying three correction factors to the one for a two-dimensional crack in a flat plate. These factors are to correct the flat plate’s KI to pipe’s one, two-dimensional crack shape to three-dimensional one, and to consider bottom head influence by the interaction. As regards a stress distribution in the wall thickness to be used, it is divided into the load control type and the displacement control one because the excessive conservativeness is excluded. Finally, the KI is calculated by superposing the one evaluated for each stress type. The evaluated KI was verified by comparing with the detailed three-dimensional FEA results. A simplified and accurate KI evaluation method for BMI nozzles in a RPV is proposed in this paper.