bluuebunny/crossref_metadata_2025 huggingface dataset:
Vibration Characteristic Evaluation of Nonlinear Vibration Systems With Gaps Considering Energy Dissipation by Collision
Authors: Shintani Masanori , Ikuta Hiroyuki , Shume Hiroyuki
Published: August 2008

This paper deals with nonlinear vibration of a continuum system with gaps under random waves considered collision phenomena. In order to investigate this nonlinear vibration characteristic, experiments are made with an experimental apparatus consisting of a nonlinear vibration system. A 2.3mm thick plate is used for the collision phenomena experiments. Moreover, an analytical model of the cubic equation is proposed based on the restoring force characteristics in the experiments. This analytical model is used for the simulation analysis, and the results are compared with the experimental results. However, the Root- Mean- Square (R.M.S.) values of the response acceleration of the analytical results are larger than R.M.S. values of the response acceleration of the experimental result. The difference of these results indicates that energy is dissipated in the collision phenomena. Then, the coefficient of restitution by the collision phenomenon between mass and plate is measured from the experiments. In the analysis, the dissipation energy is replaced with an equivalent damping ratio. The simulations are calculated by using this modified analysis. Consequently, the simulation results agree well with the experimental results.
Flow and Modal Analysis for the Investigation of PWR Safety Injection Line-Installed Thermal Sleeve Separation Failure Mechanism
Authors: Jo Jong Chull , Jhung Myung Jo , Kim Hho Jung
Published: August 2008

In conventional pressurized water reactors, a thermal sleeve (named simply ‘sleeve’ hereafter) is seated inside the nozzle part of each safety injection (SI) branch pipe to prevent and relieve potential excessive transient thermal stress in the nozzle wall when cold water is injected during the safety injection mode. Recently, mechanical failures that the sleeves are separated from the SI branch pipe and fall into the connected cold leg main pipe occurred in sequence at some typical PWR plants in Korea. This paper investigates the flow field in the pipe junction through a numerical simulation and vibration characteristics of thermal sleeves through a modal analysis to analyze the root cause of sleeve separation mechanism. By performing both flow simulation in the SI pipe junction and modal analysis of thermal sleeve, the fluid force and modal characteristics have been identified to be able to lead or contribute to separate thermal sleeves inside safety injection branch pipes in PWR plants from their original seating locations.
Visual and Versatile Hybrid Seismic Testing System Incorporated With Non-Linear Finite Element Analysis
Authors: Sakai Michiya , Keizo Ohtomo , Hagiwara Yutaka , Dozono Yoshihiro , Fukuyama Mayumi , Horiuchi Toshihiko , Konno Takao
Published: August 2008

Hybrid simulation/testing systems have been developed incorporating a non-linear finite element method with a pseudo-dynamic test. In order to ensure stability and efficiency for time integration, the incremental formulation of the α-OS method has been implemented on this system. Visualization system has also been integrated to recognize both numerical simulation for whole systems and laboratory testing for local parts. Numerical hybrid examinations of the soil structure interaction problem have been conducted on this system. By these results, validity and effectiveness of this system has been demonstrated.
Vibration Excitation Force Measurements in a Rotated Triangular Tube Bundle Subjected to Two-Phase Cross Flow
Authors: Zhang C. , Pettigrew M. J. , Mureithi N. W.
Published: August 2008

Two-phase cross flow exists in many shell-and-tube heat exchangers. Flow-induced vibration excitation forces can cause tube motion that will result in long-term fretting-wear or fatigue. Detailed vibration excitation force measurements in tube bundles subjected to two-phase cross flow are required to understand the underlying vibration excitation mechanisms. An experimental program was undertaken with a rotated-triangular array of cylinders subjected to air/water flow to simulate two-phase mixtures over a broad range of void fraction and mass fluxes. Both the dynamic lift and drag forces were measured with strain gage instrumented cylinders. The experiments revealed somewhat unexpected but significant quasi-periodic forces in both the drag and lift directions. The periodic forces appeared well correlated along the cylinder with the drag force somewhat better correlated than the lift forces. The periodic forces are also dependent on the position of the cylinder within the bundle.
Controller Evaluation Technique Using Virtual Test Model in Shaking Table
Authors: Tagawa Yasutaka , Nagai Eiji , Sato Eiji , Kajiwara Kouichi
Published: August 2008

In control system design for shaking tables, it is well known that many times and kinds of experiments have to be done to find a suitable controller. However, the control experiments with the test model on the shaking table is sometimes very difficult to implement especially for large shaking table such as E-Defense, because it costs very much for constructing and installing the test model on the shaking table. If the test model dynamics can be taken into consideration without using real test model in the experiments, these experiments cost much less than the experiments with real test model. In this study, a controller evaluation technique is proposed using a virtual test model instead of using a real test model. By using the virtual test model, it is possible to evaluate control performance when the test model is equipped on the shaking table, without using the real test model.
A Simplified Technique for Shakedown Load Determination of a 90 Degree Pipe Bend Subjected to Constant Internal Pressure and Cyclic In-Plane Bending
Authors: Abdalla Hany F. , Younan Maher Y. A. , Megahed Mohammed M.
Published: August 2008

In this paper a simple technique is presented to determine the shakedown load of a 90 degree pipe bend subjected to constant internal pressure and cyclic in-plane bending using the finite element method. Through the proposed technique, the shakedown load is determined without performing time consuming cyclic loading simulations or conventional iterative elastic techniques. Instead, the shakedown load is determined through performing only two analyses namely; an elastic analysis and an elastic-plastic analysis. By extracting the results of the two analyses, the shakedown load is determined through the calculation of the residual stresses developed in the pipe bend. In the elastic analysis, performed only once and stored, an in-plane closing moment is applied preserving structure stresses within the material elastic range. In the elastic-plastic analysis, a constant internal pressure, below the pressure to cause yielding, is applied in addition to an increasing moment magnitude that causes the material yield strength to be exceeded. For verification purposes, the results of the simplified technique are compared to the results of full cyclic loading finite element simulations where the pipe bend is subjected to constant internal pressure and cyclic in-plane closing moment loading. In order to have confidence in the proposed technique, it is applied beforehand on the Bree cylinder [1] subjected to constant internal pressure and cyclic high heat fluxes across its wall. The results of the proposed technique showed very good correlation with the, analytically determined, Bree diagram of the cylinder.
Cyclic Thermoelastoplasticity Structural Calculation: Reliability and Sensitivity of Material Parameters
Authors: Rajhi Ramzi , Taleb Lakhdar , Elhami Abdelkhalak
Published: August 2008

The essential cause of the ruptures of the structures under loadings is related most of times to the cyclical component of thermo-mechanical loadings. Forecasting the state of the structures is a very important task but simulating the structures behavior depends on a large data set of various parameters. In general, these parameters could be related to the geometry, loads and material characteristics or behavior law of the used phenomenological models. They are always known with a certain margin of incertitude that might have several origins such the experimental disparity in the material behavior or dependence on some physical variables like temperature. It is essential to measure degrees of influence of these parameters, thus the need for having analysis tools allowing the evaluation of the effects of parameters uncertainty on the structures behaviour. In this work, we study at first the reliability of the structural analyses making use of the Linear Kinematic Model of behavior in cyclic thermoelastoplasticity. Reliability will be applied to a first axis-symmetric structure. Then we propose a method based on the techniques of disturbances in order to determine the sensitivities of the phenomenological models with respect to the material parameters. This method will be applied through its two proposed approaches to a second structure. We made several assumptions. Deterministic calculations made it possible to validate the assuptions which relate to the choice of the absolute limit function. They also made it possible to confirm our expectations about the performance of the software package used (localization and values of the maximum plastic deformations). The assumption on the random variables laws are justified by the fact that the major part of the values taken are condensed around the mean value and that it is probably to exceed it as much than not to exceed it (normal law). The assumption on the value of the standard deviation holds all its validity owing to the fact that truncations must remain in conformity at the same time with the concept of density and physical limits of the variables. “The equations of dependences” make it possible to keep a sense which respects the relations of order that connects the random variables of the same nature as well reducing the cost of calculations.
Experimental and Numerical Techniques in Fluids (Invited Lecture)
Authors: Durst Franz
Published: August 2008

The development of fluid mechanics is briefly reviewed and the importance of fluid flows to heat and mass transport in nature as well as in science and engineering is outlined. The early theoretical developments are explained and it is indicated that the basic equations were already available at the end of the 18th century. Methods to solve these equations for engineering flows were not, however, developed until the second half of the 20th century. This was an important period for fluid flow research during which all the experimental fluid mechanics methods, particularly the optical methods, available today were also developed. The same is true for all the numerical methods that are used very successfully nowadays to solve scientific and engineering fluid flow problems. The Institute of Fluid Mechanics at the University of Erlangen-Nu¨rnberg has contributed extensively to these developments.
Characterization of Residual Stresses in Structural Materials for Nuclear Applications
Authors: Roy Ajit K. , Bandyopadhyay Subhra , Budugur Suresh Silpa , Wells Douglas
Published: August 2008

Residual stresses may be generated in target structural material used in accelerator-driven transmutation due to plastic deformation. Nondestructive positron annihilation spectroscopic (PAS) method has been used to estimate residual stresses in candidate structural materials such as martensitic Alloy EP-823 and Alloy HT-9. Different line shape parameters (S, W & T) obtained from the PAS measurements have been related to the degree of cold deformation. The results indicate that the magnitude of S parameter was enhanced at the intermediate level of cold deformation followed by an almost identical S value at the highest level of cold reduction. Conversely, the T parameter was reduced at higher level of cold deformation. The evaluation of the cold-worked specimens by transmission electron microscopy revealed the presence of dislocations, as expected.
Finite Element Analysis of Sloshing in Horizontal-Cylindrical Industrial Vessels Under Earthquake Loading
Authors: Platyrrachos M. A. , Karamanos S. A.
Published: August 2008

The present paper presents a finite-element formulation for earthquake-induced sloshing in horizontal-cylindrical industrial vessels. Assuming small-amplitude free-surface elevation, a linearized sloshing problem is obtained, which provides very good results in comparison with other analytical or numerical solutions, and available experimental data. The paper is aimed at calculating sloshing frequencies, as well as sloshing transient response under horizontal seismic excitation. Based on an “impulsive-convective” decomposition of the container-fluid motion, an efficient methodology is proposed for the calculation of the total seismic force, through the corresponding sloshing masses. The results from the present finite element analysis offers an efficient tool for predicting the total seismic force in horizontal cylinders and extends the current design practice for vertical cylindrical tanks stated in existing seismic design specifications.
Crack Growth Rates of Alloy 600 From the Davis-Besse Reactor CRDM Nozzle #3 in PWR Environment
Authors: Chopra Omesh K. , Alexandreanu Bogdan , Shack William J.
Published: August 2008

Reactor–vessel internal components made of nickel–base alloys are susceptible to environmentally assisted cracking. A better understanding of the causes and mechanisms of this cracking may permit less conservative estimates of damage accumulation and requirements on inspection intervals of pressurized water reactors (PWRs). This paper presents crack growth rate (CGR) results for Alloy 600 removed from nozzle#3 of the Davis–Besse (D-B) control rod drive mechanism (CRDM). The tests were conducted on 1/4-T or 1/2-T compact tension specimens in simulated PWR environment, and crack extensions were determined by DC potential drop measurements. The experimental CGRs under cyclic and constant load are compared with the existing CGR data for Alloy 600 to determine the relative susceptibility of the D-B CRDM nozzle alloy to environmentally enhanced cracking. The CGRs under constant load for the nozzle material are higher than those predicted by the best-fit curve for Alloy 600 at 316 °C. The results also indicate significant enhancement of CGRs under cyclic loading in the PWR environment. Characterization of the material microstructure and tensile properties is described.
Crack Growth Rates of A182 and A82 Alloys From the V.C. Summer Reactor Vessel Nozzle-to-Pipe Weld
Authors: Alexandreanu Bogdan , Chopra Omesh , Shack William J.
Published: August 2008

The Ni–base alloys used as construction material in light water reactors (LWRs) have experienced stress corrosion cracking (SCC). Although SCC of wrought Ni–base Alloy 600 has been observed in operating plants for many years, until recently, the weld metal Alloys 82 and 182 used with Alloy 600 environmentally assisted cracking has not been widely observed in the field. However, laboratory tests indicate that in PWR coolant environments, the SCC susceptibility of Alloy 182 may be greater than that of Alloy 600, and that of Alloy 82 may be comparable to Alloy 600. This paper presents crack growth rate (CGR) results for Alloys 182 and 82 from the reactor vessel nozzle-to-pipe from the V. C. Summer plant under both constant and cyclic load. The tests were conducted on 1/2-T compact tension specimens in a simulated PWR environment at 320 °C. Crack extensions were measured by DC potential drop measurements. Characterization of the material microstructure and is described. The SCC growth rates are compared with the existing CGR data for Ni–alloy welds to evaluate the effects of alloy type, weld microstructure, and stress intensity factor K on CGRs. The cyclic CGRs for these alloys are compared with CGRs that are expected for Alloy 600 in air under the same mechanical loading conditions to obtain a qualitative understanding of the degree and range of conditions for significant environmental enhancement in growth rates. A detailed characterization of the fracture morphology is also presented.
Analysis of Recent Fatigue Data Using the Structural Stress Procedure in ASME Div. 2 Rewrite
Authors: Dong P. , Hong J. K. , De Jesus A. M. P.
Published: August 2008

In support of the ASME Div 2 Rewrite, a master S-N curve approach has been developed using a mesh-insensitive structural stress procedure for fatigue evaluation of welded components. The effectiveness of the master S-N curve approach has been demonstrated in a number of earlier publications for many joint types and loading conditions for pipe and vessel components as well as plate joints. To further validate the structural stress method, a series of recent test data (small weld details and a full scale vessel) published by De Jesus et al (2004) were analyzed in this paper. A comparative assessment of various existing procedures and their effectiveness in correlating the fatigue test data by De Jesus et al (2004) is also presented. These assessment procedures include current ASME Sec. VIII Div 2, weld classification approach in PD 5500, and the surface extrapolation-based hot spot stress approach in recently approved European EN 13445 Standards.
Interference of Downstream Body on the Oscillation Behavior of a Circular and a Square Cylinder in Uniform Flow
Authors: Kato Naoto , Koide Mizuyasu , Takahashi Tsutomu , Shirakashi Masataka
Published: August 2008

Wind tunnel experiment showed that the Ka´rma´n vortex excitation of a circular and a square cylinder is effectively suppressed by setting another cylindrical body downstream in a cruciform arrangement with a certain gap between them, and that the galloping of a square cylinder is also completely suppressed by the downstream cylinder. However, a new oscillation is induced over a velocity range higher than that of the Ka´rma´n vortex excitation, caused by longitudinal vortices which shed periodically around the crossing. These interference effects of the downstream cylinder on the upstream cylinder oscillation are different depending on the cross-sectional configuration of the cylinders.
Ductile Fracture Evaluation of Welded Joints With a Surface Flaw Under Large Deformation
Authors: Igi Satoshi , Kubo Takahiro , Kurihara Masayoshi
Published: August 2008

Tensile tests using welded joint specimens with a surface flaw were conducted in order to study the large deformation behavior and ductile fracture of welded structural component with a flaw. Two types of 490MPa class steel plates with different yield strength are prepared for this study. The surface flaw was introduced at the center of welded metal of welded joint specimen. Strain distribution during loading and the maximum strain at ductile fracture of specimen were measured in order to investigate the influence of stress-strain properties on ductile fracture behavior of the welded joint. Three dimensional elastoplastic finite element analyses were also carried out by using the welded joint specimen models in order to calculate the detailed stress and strain distributions around notch tip. In addition, a simplified analytical model to estimate fracture strain and critical flaw size of the welded joint was proposed using the stress-strain relationship combination between base material and welded metal by Swift’s equation. The results from the analytical model show fairly good agreement with experimental results.
Quasi-Static Analysis for Subsidence of Stacked B-25 Boxes
Authors: Wu Tsu-Te , Jones William E. , Phifer Mark A.
Published: August 2008

This paper presents a quasi-static technique to evaluate the structural deformation of the four stacked B-25 boxes subjected to the static loads of overlaying soil and to determine the effect of corrosion on the deformation. Although the boxes are subjected to a static load, the structural responses of the boxes vary with time. The analytical results indeed show that the deflection, buckling and post buckling of the components of the stacked boxes occur in sequence rather than simultaneously. Therefore, it is more appropriate to treat the problems considered as quasistatic rather than static; namely, the structural response of the stacked boxes are dynamic but with very long duration. Furthermore, the finite-element model has complex contact and slide conditions between the interfaces of the adjoining components, and thus its numerical solution is more tractable by using explicit time integration schemes. The analysis covers the three corrosion scenarios following various time lengths of initial burial under an interim soil cover. The results qualitatively agree with expected differences in deformation for different degrees of corrosion subsidence potential reduction that can be achieved.
PERFECT — Prediction of Irradiation Damage Effects in Reactor Components: Overview of RPV Mechanics Sub-Project
Authors: Lidbury David , Bugat Ste´phane , Diard Olivier , Keim Elisabeth , Marini Bernard , Viehrig Hans-Werner , Wallin Kim
Published: August 2008

The EURATOM 6th Framework Integrated Project PERFECT (Prediction of Irradiation Damage Effects in Reactor Components) addresses irradiation damage in RPV materials and components by multi-scale modeling. This state-of-the-art approach offers many potential advantages over the conventional empirical methods used in current practice of nuclear plant lifetime management. Launched in January 2004, this 48-month project is focusing on two main components of nuclear power plants which are subject to irradiation damage: the ferritic steel reactor pressure vessel, and the austenitic steel internals. It is the purpose of the present paper to provide an overview of work being carried out in the RPV Mechanics Sub-project of PERFECT to predict the fracture behavior of PWR, BWR and WWER systems.
Glass Crushing for Recycling Using Underwater Shock Wave
Authors: Iyama Hirofumi , Watanabe Toshiaki , Itoh Shigeru
Published: August 2008

Much construction scrap is discharged when a dwelling or a building are disassembled. Wood is tipped. Concrete is recycled to new object for concretes, the aggregate for pavement, etc. Glass is classified and crushed, and is recycled by the materials of the glass called cullet. However, in fact, only rough classifying was performed, a little construction scrap is recycled and many materials have been disposed by reclamation. In order to raise the rate of recycling of glass, it not only raises the rate of classify at the disassembling, but it is necessity of also processing to a cullet. On a glass plate with adhesion sheet for crime prevention, because the resin ingredient mixes, it is difficult to make it to the cullet. For this reason, it is necessary to develop an effectively technique for crushing and making to cullet of the glass with resin. Then, we are have examined that only glass is crushed using an underwater shock wave, and it easily separated in to the glass and resin.
Thermal Properties of Fiberboard Overpack Materials in the 9975 Shipping Package
Authors: Vormelker P. R. , Daugherty W. L.
Published: August 2008

The 9975 shipping package incorporates a cane fiberboard overpack for thermal insulation and impact resistance. Thermal properties (thermal conductivity and specific heat capacity) have been measured on cane fiberboard and a similar wood fiber-based product at several temperatures representing potential storage conditions. While the two products exhibit similar behavior, the measured specific heat capacity varies significantly from prior data. The current data are being developed as the basis to verify that this material remains acceptable over the extended storage time period.
Elastic Interaction Between Fasteners in Gasketed Bolted Joints
Authors: Nassar Sayed A. , Alkelani Ali A.
Published: August 2008

An experimental study is presented in order to determine the effect of several parameters on the elastic interaction between various fasteners in a gasketed joint. Parameters include the gasket thickness, bolt spacing, tightening sequence, fastener grip length, and the level of fastener preload. The joint is made of two steel flanges with a Styrene Butadiene Rubber gasket of various thicknesses. The joint is fastened together using 1/2” - 13 SAE Grade 8 fasteners that are specially instrumented to measure the initial preload and the residual tension in each fastener. Four different gasket thicknesses are considered, namely, 1/16”, 1/8”, 3/16”, and 1/4”. For the same bolt circle of the flange, bolt spacing is varied by using different number of bolts; spacing that corresponds to using three, five, or seven bolts are considered in this study. The effect of the tightening sequence is studied by using sequential bolt tightening, star pattern, and simultaneous tightening. Bolt tightening is accomplished by using either an electric digital torque wrench with various control options, or a production-size multiple spindle fastening system that is capable of simultaneous tightening of all fasteners using torque, torque-turn, or torque-to-yield control of each fastener.
Monte Carlo Simulation of Fretting Wear Performance of Fuel Rods
Authors: Rubiolo Pablo R.
Published: August 2008

The effect of the diverse parameters affecting the fretting-wear performance of nuclear fuel rods is investigated by performing Monte Carlo simulations with a fuel rod vibration model. The study is focused on the analysis of the effect of the grid parameters, including the cell clearance and the grid/support misalignments, on the support preload forces distribution, the rod dynamic response and the overall wear damage. In the present approach, the fuel rod and grids are modeled as a beam constrained at a finite number of axial positions and a non-linear vibration model is used to predict the rod motion and the wear rates. The results of the analysis suggest that an important fraction of the variability of the assembly wear damage distribution can be explained by the local variations of the rod-support conditions.
Effectiveness of Substituting Ultrasonic Testing for Radiographic Testing for Repair/Replacement
Authors: Spanner Jack
Published: August 2008

Technical justifications and demonstrations are needed by utilities to substitute ultrasonic examinations for radiographic examinations during repair/replacement activities. This paper provides technical justification and demonstration results for using this alternative inspection method. It also provides a potential demonstration process that could be acceptable to regulators and authorized nuclear in-service inspector agencies.
Condensation-Induced Water Hammer in District Steam Systems: Circumstances Resulting in Catastrophic Failures
Authors: Kirsner Wayne
Published: August 2008

Waterhammer accidents in district steam systems which kill operators are, in my experience, always due to Condensation-Induced Waterhammer. The other classifications of waterhammer that can occur in steam systems: Column-Closure, Sudden Choking at an Orifice due to flashing hot water, sudden valve closure, and steam-blown slug flow (which is not, technically, waterhammer) don’t generally result in overpressures powerful enough to breech steam components. This paper describes the most prevalent circumstances which lead to catastrophic waterhammer accidents in district steam systems based on the author’s experience in steam accident investigations. Examples are drawn from actual accidents to describe each circumstance. The circumstances can be grouped into two distinct causation categories—both of which are necessary for condensation-induced waterhammer to occur. I. Circumstances which allow excess condensate to accumulate in a steam system. II. Circumstances which permit steam to come into contact with, and be entrapped in, the condensate.
An Approach for Fatigue Life Prediction
Authors: Jiang Yanyao , Ding Fei , Feng Miaolin
Published: August 2008

Fatigue damage is generally described as the nucleation and growth of cracks to final failure. These two stages of fatigue damage are often modeled with completely different methods with no quantitative relationships between them. In addition, a number of fitting parameters are needed in order to consider different effects. The current work is aimed to develop a robust approach for the prediction of fatigue life from crack initiation to final fracture. The approach bridges the gap between the crack nucleation and growth regions. Based upon the conception that fatigue damage is directly related to the stresses and strains inside the material, it is assumed that both crack nucleation and crack growth are governed by the same fatigue damage mechanisms and a single fatigue damage criterion can model both stages. A basic rule is that any material point fails to form a fresh crack if the total accumulated fatigue damage reaches a limit. Crack growth is treated as a process of continuous crack nucleation without using the stress intensity factor or J-integral concept. The approach consists of two steps: stress analysis and fatigue damage prediction. Elastic-plastic stress analysis is conducted for the component to obtain the detailed stress-strain responses. By using a general fatigue criterion, fatigue crack nucleation and growth are predicted. Notched specimens made of 1070 steel were experimentally tested from crack initiation till fracture. The approach was applied to predict the fatigue life of 1070 steel and the predicted fatigue lives were in excellent agreement with the experimental observations.
Fatigue Crack Propagation of 304 Stainless Steel in High Temperature Water: Additional Tests and Data Correlation
Authors: Wire G. L. , Evans W. M. , Mills W. J.
Published: August 2008

Fatigue crack propagation (FCP) testing of 304 stainless steel (304 SS) specimens showed a strong acceleration of rates in high temperature water with 40–60 cc H2/kg H2O at 243°C and 288°C, with rates up to 20X the air rates [1]. However, FCP rates were markedly reduced for a second heat at long rise times and for both heats with addition of a constant load hold time of 1200 s at a high stress ratio [2]. Such behavior had not been previously reported in the literature and merited further investigation. Tests have been extended to include two additional heats and a wider set of loading conditions. FCP rates were accelerated at long rise times in the two additional heats, consistent with a large series of tests on wrought, weld, and cast austenitic stainless steel materials recently reported by Nomura, et al. [3]. Hold time tests at a lower stress ratio showed that small increases or decreases in rate occur with holds at minimum or maximum load, but the changes were within normal data scatter. The rate reductions are not a generic result of less frequent cycling, but are limited to specific loading parameters or heats. A time-based correlation successfully describes the accelerated rates observed on all four heats, and is nearly identical to fits of literature data in PWR water and hydrogen water chemistry (HWC). A power law fit with separate terms for rise time, ΔK, and stress ratio provides an equivalent correlation.
A Condition for an Air Entrainment by Breaking the Surface Waves at the Free Surface
Authors: Nam Ho-Yun , Kim Jong-Man , Choi Byoung-Hae , Choi Jong-Hyeun
Published: August 2008

An experimental study has been carried out to measure the critical conditions for the inception of an air entrainment by breaking the surface wave at the free surface in the water test facility. The experimental parameters are the vessel diameter, the nozzle diameter, the mean water-level and the water flow rate. More than 400 experimental data which show whether the air is entrained or not at a given experimental condition are obtained, and an experimental correlation that describes the air entrainment condition is developed. The correlation is described by the ratio between the diameter and height of the vessel, the ratio between the diameter of the nozzle and the height of the vessel, the modified Froude number and a modified Weber number. In this experiment two cases of air entrainment are observed. One case is that the air entrainment occurred due to the destruction of the surface wave from the center, and the other case is due to the crash of the water wave to the vessel wall. Theses two cases occur irregularly and the entrained air bubble distributes uniformly in the water.
Irradiated RPV Steels: The EU PERFECT Project Towards a Multi-Scale Modelling of Microstructure and Plasticity
Authors: Boutard Jean-Louis
Published: August 2008

The in-service hardening and increase of the Ductile Brittle Transition Temperature (DBTT) of Reactor Pressure Vessel (RPV) steels are controlled at the atomic scale by the clustering of point defects with co-segregation of alloying elements like Cu, Mn, Ni, Si and P. The effort and strategy within the European Project PERFECT for developing advanced multi-scale numerical tools to predict this microstructure and the induced hardening as well as their experimental validation at the relevant scale will be presented. The first results obtained since January 2004, starting date of PERFECT, will be discussed and perspectives given.
Digital Radiography of General Purpose Fissile Packages
Authors: Howard Boyd , Gelder Larry
Published: August 2008

Digital radiography provides an effective means of non-destructively examining the effects of physical tests on the interior structure of a Radioactive Materials Packaging. As such it enables evaluation of the effects of the Hypothetical Accident Conditions Sequential Test on a package, following each step in the test sequence. An introduction to digital radiography is given and application of CCD-based, lens-coupled, large area-detector, digital radiography in the HAC testing of the prototype General Purpose Fissile Packaging is described. The radiographs enable correlation of damage with particular steps in the test sequence.
Numerical Simulation of CrMo Steels Thick Welds Intermediate Postweld Heat Treatments
Authors: Clerge´ Maryline , Boucher Christian , Pillot Sylvain , Bourges Philippe
Published: August 2008

During manufacturing, complex shape welded pressure vessels are submitted to numerous intermediate heat treatments after each weld (de-hydrogenation treatment - DHT and/or intermediate stress relieving treatment - ISR) before final Post Weld Heat Treatment (PWHT). The present study aims at analysing and optimising the intermediate heat treatment conditions regarding the resulting mechanical properties (tensile strength and impact. strength) of CrMo and CrMoV creep resistant steels. Hydrogen behaviour in weld metal and HAZ, and residual stresses evolution have been assessed by numerical modelling and experimental measurements on welded specimens representative of big pressure vessels: butt welds and set in nozzle welds of 150 mm wall thickness. The optimised conditions are compared to usual construction codes and buyer’s requirements.
Assessment of ASME Code Examinations on Regenerative, Letdown and Residual Heat Removal Heat Exchangers
Authors: Gosselin S. R. , Simonen F. A. , Cumblidge S. E. , Tinsley G. A. , Lydell B. , Anderson M. T. , Doctor S. R.
Published: August 2008

Inservice inspection requirements for pressure retaining welds in the regenerative, letdown, and residual heat removal heat exchangers are prescribed in Section XI Articles IWB and IWC of the ASME Boiler and Pressure Vessel Code. Accordingly, volumetric and/or surface examinations are performed on heat exchanger shell, head, nozzle-to-head, and nozzle-to-shell welds. Inspection difficulties associated with the implementation of these Code-required examinations have forced operating nuclear power plants to seek relief from the U.S. Nuclear Regulatory Commission. The nature of these relief requests are generally concerned with metallurgical factors, geometry, accessibility, and radiation burden. Over 60% of licensee requests to the NRC identify significant radiation exposure burden as the principal reason for relief from the ASME Code examinations on regenerative heat exchangers. For the residual heat removal heat exchangers, 90% of the relief requests are associated with geometry and accessibility concerns. Pacific Northwest National Laboratory was funded by the NRC Office of Nuclear Regulatory Research to review current practice with regard to volumetric and/or surface examinations of shell welds of letdown heat exchangers, regenerative heat exchangers, and residual (decay) heat removal heat exchangers. Design, operating, common preventative maintenance practices, and potential degradation mechanisms were reviewed. A detailed survey of domestic and international PWR-specific operating experience was performed to identify pressure boundary failures (or lack of failures) in each heat exchanger type and NSSS design. The service data survey was based on the PIPExp® database and covers PWR plants worldwide for the period 1970–2004. Finally a risk assessment of the current ASME Code inspection requirements for residual heat removal, letdown, and regenerative heat exchangers was performed. The results were then reviewed to discuss the examinations relative to plant safety and occupational radiation exposures.
Explicit and Implicit Code Coupling Schemes in Fluid Structure Interaction
Authors: Longatte E. , Bendjeddou Z. , Verreman V. , Souli M.
Published: August 2008

In multi-physics numerical computations a good choice of code coupling schemes is required. Several methods are possible like: an explicit synchronous scheme an Euler implicit method and no interpolation on velocity pressure; an explicit asynchonous scheme using a Crank-Nicholson time integration scheme and interpolation on velocity and pressure; an implicit scheme using a fixed iterative method. In the present paper these different schemes are compared for application in fluid structure interaction field. In the first part numerical coupling schemes are presented. Then their capability to ensure energy conservation is discussed according to numerical results obtained in analytical test cases. Finally application of coupling process to fluid structure interaction problems is investigated and results are discussed in terms of added mass and damping induced by a fluid for a structure vibrating in fluid at rest.
Hydrodynamic Ram Analysis of Non-Exploding Projectile Impacting Water
Authors: Poehlmann-Martins Flavio , Gabrys Jon , Souli Mhamed
Published: August 2008

Hydrodynamic pressures generated by a non-exploding projectile penetrating a fuel tank can be very destructive. Understanding the magnitude of the pressure and its distribution inside the tank is critical for designing structure to survive these incidents. This project uses LS-DYNA to simulate a hydrodynamic ram event created by a steel ball, traveling at a high rate, impacting a tank of water. Predicted pressures are then compared to measured pressures for validation. Additionally, modeling parameters such as element size and penalty factors for fluid structure coupling are investigated. Different ways to model reflections of pressure waves off the sidewalls are studied, as well. Good correlation is achieved for pressures at many locations inside the water tank.
Airplane Tire Burst Plume Analysis
Authors: Lee Ryan , Gabrys Jon
Published: August 2008

On rare occasion, aircraft tires have burst in flight after being retracted into the wheel well. The burst rapidly releases a high-pressure plume of gas that may cause damage to systems and structure mounted in the wheel well. Since airplanes must be designed to maintain continued safe flight and landing following a tire burst in the wheel well, it is essential that accurate definitions of the plume pressure loads be provided to the airplane structural and systems designers. Existing plume load definitions have been developed over the years from test data and theoretical calculations, but given the very short duration of the event and the complexity of the dynamics involved, it is desired to validate the existing threat definitions through the use of advanced finite element modeling. This paper describes the use of LS-DYNA to accurately predict the pressure plume created from the controlled release of a pressurized tank. This task is considered part of the validation phase. The next step will include the complexities of the deforming tire to quantify the effect of the rapidly changing hole diameter, and to study how the solution diverges from the classical prediction.
Numerical Study of Overdriven Detonation Phenomenon
Authors: Mahmadi K. , Souli M. , Aquelet N.
Published: August 2008

The overdriven detonation refers to detonation process in which the main detonation parameters, such as detonation pressure and propagating velocity, exceed the corresponding Chapman-Jouguet (C-J) values. This kind of detonation can be occurred when the flyer plate of high velocity impacts the explosive. So, in this work numerical simulation of overdriven detonation (following O.D.D.) phenomenon, which brings out higher detonation pressures than C-J pressure of an explosive is considered. The shock-structure interaction in this fast event is modeled by a penalty coupling, which permits to couple a Lagrangian mesh of the plate to material points of a multi-material Eulerian flow. This technique has been used successfully in many areas of applications, including automotive and industrial fields. By using an explicit finite element method, a good agreement between numerical and experimental results will valid penalty coupling capabilities to solve accurately O.D.D. phenomenon.
Fluid Structure Interaction and Airbag ALE for Out of Position
Authors: Souli M’hamed , Capron Nicolas , Khan Uzair
Published: August 2008

A new fluid structure interaction method is presented in the paper. The method is implemented in LSDYA, an explicit three-dimensional multi-physique code. The new algorithm is applied for different problems for industrial applications including airbag deployment in the automotive industry, where a uniform pressure computed empirically is applied to the airbag fabric material. The uniform pressure Airbag simulation does not lead to the right answer for out of position Airbag deployment. An ALE method using fluid mesh for the gas needs to be used to simulate an impact of dummy and the airbag during a crash test. In this paper, we develop the new ALE multi-material formulation and the fluid structure interaction algorithm that we developed in order to solve general fluid structure interaction problems including Airbag inflation using hydrodynamic equations for gas pressure. In the classical uniform pressure problems, the pressure in computed using a simple ideal gas law equation.
The ASME Section XI Code and the Future
Authors: Park Gary
Published: August 2008

This paper will describe the process under which the ASME Section XI Subcommittee works in addressing industry initiatives and setting of priorities and goals. Each calendar year an Operational Plan is developed which comprises the priorities and goals established for the different Subgroups and Working Groups that report directly to the Subcommittee XI. These goals include committee actions developed to respond to industry initiatives and concerns. This Operational Plan also helps establish the “work-list” of each Subgroup. This work-list provides the priority of the items to be worked on for the upcoming year. Just as any other business, the Subcommittee on Nuclear Inservice Inspection manages and prioritizes activities to meet the industry needs.
A New Embedded-Zone Method on Computation of the Transverse Elastic Properties of Fiber-Reinforced Composites
Authors: Wang Xiaochun
Published: August 2008

There are many methods on computation of transverse elastic properties of unidirectional fiber-reinforced composites when using the finite element method, such as three-dimension model, two-dimension plane strain model, unit cell model, etc[1]. But unit cell models could be used only when the fibers are arrayed regularly. The computations of three- and two-dimension plane strain models are tremendous when many fine fibers are spread randomly in the matrix so that the properties of block of composite must be computed. The paper proposes a new embedded-zone method to compute the transverse elastic properties for a block of fiber-reinforced composites containing a great amount of fibers embedded in the matrix stochastically while using very little computational work compared with three- and two-dimension plane strain model. The transverse elastic modulus and shear modulus of unidirectional fiber-reinforced composites are computed.
Geologic and Environmental Probe System (GEOPS)
Authors: Clark D. T. , Jones R. L. , Valenti L. N.
Published: August 2008

This paper describes the engineering design and development of a novel 2004 R&D 100 award winning probe system that is used to monitor and collect samples from within waste areas safely — without negative exposure to the environment or people. The Idaho National Laboratory (INL) has developed a multiple-use, low-cost subsurface probing system to safely sample and monitor targeted subsurface areas, from within and below abandoned or active landfills, mining areas, farms, airports, or from any of the more than 77,000 identified potentially hazardous waste sites across the U.S. The probe system uses a unique probe casing and tip system that—once placed in a zone of interest—accepts instrument inserts to provide invaluable potential contaminate transport or other data from saturated or unsaturated waste zones, or from groundwater zones. The Geologic and Environmental Probe System (GEOPS) is the newest generation of INL-developed subsurface probes. The system’s robust probe casing platform is installed into or below a waste zone using direct push or sonic drill rigs, using a technique similar to pushing a needle into an apple. Subsurface conditions are not disturbed as in rotary drilling operations, cuttings are not brought to surface during installation, and workers and the surface environment are isolated from contaminants. One key to the capture of samples from the extremes of the subsurface using the GEOPS is the probe tip system. The specially designed tip utilizes a cylindrical section of sintered steel that has small pore openings and are used to filter liquid and gas samples from surrounding soil (i.e., area of interest) into the probe system. The sintered steel filter has reduced material properties, as compared to the probe casing platform and is vulnerable to high loadings, as would be experienced during probe installation. The probe tip system was specially designed to shield the filter component from large compressive and tensile loading and deliver it safely to a target depth. Once the casing is at the desired sampling depth, the instruments are placed into the platform, a vacuum is imposed on the system, and vapor and liquid subsurface samples are brought safely to surface though the sintered steel filter.
Deformation Mechanisms of Electroformed Nanocrystalline Nickel-Phosphorous Alloy at 616K
Authors: Pop Mike G. M. , Galford James E.
Published: August 2008

The creep deformation model of an electroformed nanocrystalline nickel-phosphorous repair material is examined in this paper, at the design temperature of 616K (650K), characteristic for the majority of Pressurized Water Reactor (PWR) nuclear power plants. The results from 15 constant load creep tests of this material, at stresses between 103 MPa and 483 MPa, were used to validate the model. The total creep rate determined with the model suggested in this paper, based on two predominant deformation mechanisms, is also compared with the literature.