bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Probabilistic Fracture Mechanics Evaluations for a Through-Wall Cracked Pipe Under the STYLE Project
Authors: Sharples John , Madew Colin , Radu Vasile , Budden Peter
Published: November 2014

One of the large scale mock-up experiments (Mock-Up 2) of the recent STYLE European project was a ductile fracture test carried out on a pipe containing a circumferential through-wall crack located in a repair weld and loaded under four-point bending. This experiment has been used as a basis for undertaking a comparative probabilistic fracture mechanics benchmark study by a number of the organisations participating in STYLE.

In launching the benchmark study, the pipe and crack dimensions were specified as fixed values, applied bending stress (moment) was considered as a deterministic variable and three values were taken for weld residual stress (assuming constant membrane values). Tensile and fracture toughness material properties were considered to be random variables and these were specified by log-normal distribution parameter values. In undertaking their evaluations, the participants were asked to evaluate J-integral versus applied bending moment, probability of crack growth initiation versus applied bending moment, probability of net-section collapse versus applied bending moment and carry out various sensitivity analyses.

This paper focuses mainly on the contribution to the benchmark study primarily based on the R6 methodology and includes examples of contributions provided using other methods.
Statistical Analyses of High Cycle Fatigue French Data for Austenitic SS
Authors: Blatman Géraud , Métais Thomas , Le Roux Jean-Christophe , Cambier Simon
Published: November 2014

In the 2009 version of the ASME BPV Code, a set of new design fatigue curves were proposed to cover the various steels of the code. These changes occurred in the wake of publications [1] showing that the mean air curve used to build the former ASME fatigue curve did not always represent accurately laboratory results.

The starting point for the methodology to build the design curve is the mean air curve obtained through laboratory testing: coefficients are then applied to the mean air curve in order to bridge the gap between experimental testing and reactor conditions.

These coefficients on the number of cycles and on the strain amplitude are equal to 12 and 2 respectively in the 2009 ASME BPV code, using the mean air curve proposal from NUREG/CR-6909 [1]. Internationally, with the same mean air curve, other proposals have emerged and especially in France [2]-[3] where a consensus seems to be reached on the reduction of the coefficient on strain amplitude.

This paper provides statistical analyses of the experimental data obtained in France at high-cycle for austenitic stainless steels. It enables to bring arguments for the selection of a coefficient on strain amplitude in the French RCC-M code, where less scatter on the data is witnessed due to fewer material grades.
Vortex Shedding Lock-In due to Stream-Wise Oscillation of a 2-D Wind Turbine Blade Section at High Angles of Attack
Authors: Pellegrino Alberto , Meskell Craig
Published: November 2014

The unsteady, incompressible flow around a translating two-dimensional wind turbine blade section (NREL S809) in the stream-wise direction has been simulated using unsteady RANS with the transition SST turbulence model. The Reynolds number is Re = 106 referred to a chord length of 1 m. A prescribed sinusoidal stream-wise motion has been applied at a fixed amplitude of 0.25 m for a range of high angles of attack [30° < α < 150°]. At these incidences, the airfoil will behave more like a bluff body and may experience periodic vortex shedding. It is well known that oscillations can lead to a synchronization (lock-in) of the vortex shedding frequency, fv, with the body’s motion frequency, fs, in bluff body flows. In order to investigate the susceptibility of the wind turbine blade section to lock-in, a parametric study has been conducted varying the frequency ratio r, (r = fs/fv0), in a range around r = 1 and r = 0.5. The lock-in region boundaries have been proposed and an analysis of the effect of the oscillation amplitude has been conducted. The synchronization map obtained suggests that, for the vibration amplitude considered, the risk of vortex-induced vibration is more significant in the regions of α = 35° and α = 145°. Furthermore, it has been found that for some stream-wise amplitudes, increasing the oscillation amplitude, lock-in appears to be unexpectedly suppressed in the vicinity of r = 1.
Cleavage Crack Propagation and Arrest Prediction in French PWR Vessel Steel
Authors: Yang Xiaoyu , Marie Stéphane , Bompard Philippe , Jacquemoud Clémentine
Published: November 2014

The integrity assessment of Reactor Pressure Vessels is mainly based on crack initiation. Nevertheless, in the frame of component life extension, crack arrest conception is investigated.

This paper presents a local non-linear dynamic model to predict the propagation and arrest of cleavage crack in French PWR vessel steel (16MND5). The propagation criterion used in this model is a Ritchie Knott and Rice (RKR) fracture stress criterion: the crack propagates when the maximum stress ahead of crack tip reaches a critical level, which has been shown to depend on temperature and plastic strain rate.

In the first step, the criterion has been identified from crack growth and arrest analysis on CT specimens at different temperatures. Then it was applied to predict the propagation and arrest of cleavage cracks on pre-cracked rings under mixed mode loading, at three different temperatures: −150°C, −125°C and −100°C.

2D modeling was performed by using extended element method (XFEM) in CAST3M software. The propagation direction on pre-crack rings under mixed mode loading was determined from maximum hoop stress criterion. Numerical computation showed a good agreement with experiments, for both curved crack paths and crack arrest locations. Furthermore it showed that crack paths and crack arrest also depend on the level of the crack loading at initiation.
Nuclear Regulatory Commission Staff View of Progress in the Nondestructive Testing of Cast Austenitic Steel Components
Authors: Cumblidge Stephen E.
Published: November 2014

Welds in cast austenitic steels (CASS) are very challenging to inspect using the current American Society for Mechanical Engineers (ASME) Boiler and Pressure Vessel Code Section XI requirements. Supplement 9 of ASME Boiler and Pressure Vessel Code Section XI, Appendix VIII is still in the course of preparation, requiring inspectors to use ASME Code Section XI, Appendix III, which provides prescriptive ultrasonic testing (UT) requirements that are significantly less rigorous than UT techniques that have been demonstrated under Appendix VIII. The inability of licensees to demonstrate that the welds in CASS components meet ASME Code requirements has been an ongoing area of concern for the NRC staff. The lack of a reliable inspection method for welds in CASS materials has led to hundreds of relief requests over the past four decades. While no degradation mechanism has been found in CASS components to date, there is no guarantee that a new degradation mechanism affecting CASS welds will not emerge as nuclear power plants go beyond forty years of operation. Licenses need qualified procedures and personnel for the inspection of welds in CASS materials in order to put licensees into compliance with ASME Code, meet federal regulations, reduce the number of needed relief requests, and ensure the structural integrity of their welds.

Over the past decade there have been significant developments in nondestructive examination (NDE) technology. The use of encoded phased array techniques using low frequency ultrasound has been shown to be able to reliably find flaws greater than 30% through wall in CASS materials with a variety of microstructures. Additionally, an improved understanding of the fracture mechanics of CASS components is being developed that shows the flaw sizes that can be tolerated in CASS components. These advances in NDE techniques and fracture mechanics theory are converging on a path to allow for qualifications of procedures and personnel for the ultrasonic inspections of welds in CASS components.

Recent developments in ASME Code includes Code Case N-824, which provides guidance on the examination of CASS materials based on the advances in NDE technology and an improved understanding of the NDE techniques capable of finding flaws in CASS components as well as Code Case N-838 for flaw tolerance evaluations of CASS piping components. Finally, work on ASME Code Section XI Supplement 9 is progressing, with several important issues still to be addressed. The NRC staff sees a clear path forward and is working to ensure that qualified inspections of welds in CASS materials will be possible in the future.
External Nozzle Load Evaluation for Filament Wound FRP Cylindrical Vessels
Authors: DeCola Dale W. , Eisenman Jeffrey D.
Published: November 2014

The evaluation of external nozzle loading on filament wound Fiber Reinforced Plastic (FRP) storage tanks and pressure vessels can be a challenging task. While established methods for metallic vessels exist, limited guidance is available to account for the unique characteristics of FRP composite materials and standard FRP fabrication practices. Anisotropic material properties can have a significant effect on the stress/strain distribution due to external nozzle loading. Typical FRP nozzle installation practices introduce additional concerns, including the potential for peeling or overstraining the nozzle attachment overlays. In this paper, the effects of various orthotropic material properties of cylindrical vessels with external nozzle loading are explored using finite element analysis and compared with existing methods established for isotropic materials. Modifications to account for the effects of filament wound FRP material properties are proposed. A simplified FRP nozzle load evaluation procedure, along with additional commentary, is presented to address some of the special considerations regarding nozzle load evaluation for FRP storage tanks and pressure vessels.
Thermal Ratcheting Test Results for Alloy 617
Authors: Wang Yanli , Sham T.-L. (Sam) , Jetter R. I.
Published: November 2014

Alloy 617 has been selected as a reference material supporting the Very High Temperature Gas Cooled Reactor (VHTR). However, current simplified design methods in Subsection NH have been deemed inapplicable at very high temperatures because, at these conditions, it is not possible to decouple plasticity and creep which is the basis for the current methods. Also, the alternative use of inelastic analysis requires development and verification of material modeling at these very high temperatures. A test procedure has been developed and implemented to support verification of new simplified methods and material modeling of Alloy 617 at very high temperatures. The procedure is based on two bars tested in series using two coupled servo-controlled testing machines to achieve equal displacement and constant applied load, mimicking the behavior of a pressurized cylinder subjected to through wall thermal transients. The tests were conducted with a hold time at 950°C. The bars were heated and cooled out of phase to generated thermal induced loading superimposed on a constant mean stress. The results are presented for different mean stress levels, heating and cooling rates, and thermal histories.
Use of Laser Measurement Systems for Out-of-Roundness Check of ASME BVP Section VIII Div.1 Pressure Vessels
Authors: Millet Barry , Di Lillo Patrizio , Whipple Richard , Kirkpatrick Kenneth , Miller George
Published: November 2014

Since the 1956 Edition of the ASME Boiler and Pressure Vessel Code Section VIII (ASME B&PV Code) [1], the Out-of-Roundness of circular sections of pressure vessels subject to external pressure have been inspected using a segmental template per paragraph UG-80(b)(2). Newly approved ASME Code Case 2789 “Laser Measurement for Out-of-Roundness Section VIII, Division 1” to the ASME B&PV Code expands the out of roundness checking to allow the use of laser measurement systems. Today with large vessels approaching 60 feet (18.2 m) in diameter, laser measuring systems allow an expeditious and cost effective method of inspection for out-of-roundness.

The Code Case allows the fabricator to use measurements obtained from laser measuring to either verify the vessel in the arc segments or the entire vessel circumference is held to a circularity tolerance. The second option is similar to the requirements of European Standard EN 13445 (EN 13445) [2] which uses circularity.

This paper will explore the origin and objective of the template and presents how laser measuring systems make use of the latest technology available to check for out-of-roundness. The paper will address laser measuring systems, procedures for taking measurements, and processing of the data into a format that can be verified by Authorized Inspectors.
Prediction of Packed Catalyst Bed Stress and Load for Radial Flow Reactors
Authors: Zhao Mingxin , Vargas Pedro
Published: November 2014

For the radial flow reactor with a packed catalyst bed, the pressure drop in radial direction will affect bed support stress and load condition significantly. Increased fines due to catalyst attrition during operation will increase the radial pressure drop. For an extreme case, the entire catalyst bed could be pushed inward and pinned to the reactor’s perforated center screen, potentially causing the internal components to be overly stressed by the excessive load. Understanding the impact of radial pressure drop to bed stress and load distribution is very important for reactor internals design and operation. In this study, a generic packed catalyst bed for a radial flow reactor is analytically modeled and examined for stress and load by a classical granular solid material model, i.e., Janssen’s theory, which is further modified to include the pressure drop effects for a radial flow reactor. Interactions between bed stress, load, and radial pressure drop are explored. The critical condition is derived.
Simple Model for Bubble-Wall Interaction
Authors: Pelletier Etienne , Beguin C. , Etienne S.
Published: November 2014

We have developed a model for an ellipsoidal bubble colliding with a rigid horizontal wall based on potential flow theory. The model is then compared with experiments of air bubbles surrounded by water impacting a wall. 70 impacts were observed with bubble radius between 0.3 and 2 mm and different trajectory types (helicoidal, zig-zag). Deformation and height of the first impact are the main comparison points. The proposed model is in good agreement with the height of the rebound but tends to overestimate the maximal compression for both types of trajectories.

We also propose a new relation for the viscous drag coefficient correction induced by the wall confinement as well as the definition of potential pressure forces acting on bubbles close to a wall.
Wall Proximity and Curvature Effect on Added Mass Forces in Two-Phase Cross-Flow
Authors: Béguin C. , Plagnard T. , Étienne S.
Published: November 2014

This paper studies the effect of wall proximity and wall curvature on the added mass coefficient of a spherical bubble. Results are based on a semi-analytical method. This information is essential to completely characterize finely dispersed bubbly flows in two-phase cross flow. In such flows small spherical gas bubbles are present in a continuous liquid phase close to a cylinder. This paper uses solid harmonics to solve 3D potential flow around a bubble and a wall. A new technique is developed to calculate the flow potential around a sphere and a cylinder using solid harmonics. Several configurations were calculated: one bubble close to an infinite wall, one bubble close to a cylinder and one bubble close to a spherical wall. Our results are compared with previous studies. As expected added mass forces increase in the vicinity of the wall and for lower curvature. The main purpose of this work is to understand the effect of wall curvature and proximity on added mass. These results are suitable for further use, particularly as added mass models for multiphase flow averaged equations.
Technical Basis for Proposed Revisions to Code Case N-806, Evaluation of Metal Loss in Class 2 and 3 Metallic Piping Buried in a Back-Filled Trench
Authors: McGill Robert O. , Moenssens Mark A. , Antaki George A. , Scarth Douglas A.
Published: November 2014

ASME Section XI Code Case N-806, for evaluation of metal loss in Class 2 and 3 metallic piping buried in a back-filled trench, was published in 2012. This Code Case has been prepared by the ASME Section XI Task Group on Evaluation Procedures for Degraded Buried Pipe. The Code Case addresses the nuclear industry need for evaluation procedures and acceptance criteria for the disposition of metal loss that is discovered during the inspection of metallic piping buried in a back-filled trench. A number of improvements have been proposed for Code Case N-806. These include improvements to the analytical procedures for structural integrity evaluation under soil and surcharge loads. In addition, tables of soil properties and other parameters needed in the evaluation are proposed to be provided to improve ease of use. This paper presents the technical basis for the proposed revision to Code Case N-806.
Simplified Methodology for Analysis of Reflected Detonation and DDT: Part 2 — Elastic-Plastic Analysis
Authors: Ligon Thomas C. , Gross David J. , Minichiello John C.
Published: November 2014

This paper applies a simplified conservative approach for analyzing elastic-plastic response of piping due to reflected gaseous detonations and deflagration-to-detonation transitions (DDT). A consequence associated with gaseous explosions is the potential for DDT to occur near the end of a closed pipe or gas pocket. As an accelerating deflagration flame approaches a closed end, the unburned fuel ahead of the flame front is compressed to an elevated initial pressure. This process is often referred to as pressure piling or pre-compression, and the combination of detonation reflection with the elevated initial pressure can produce extremely high peak pressures and large values of impulse. In this paper, the event where DDT occurs immediately ahead of the reflecting surface is referred to as a reflected-DDT (R-DDT). Due to the extreme pressures that R-DDTs can achieve, the piping can frequently experience elastic-plastic deformation.

In this second part, the pressure time-history modeling methodology developed for elastic response in part one is extended to elastic-plastic analysis. The inelastic response of the piping material is modeled using a lower-bound strain hardening curve at a single representative strain rate. The pressure model is compared to a published reflected detonation pressure model for the stoichiometric mixture of ethylene and oxygen, and finite-element analysis results using the simplified methodology are compared to two recent sets of published plastic deformation data from ethylene oxygen explosion tests in austenitic stainless steel tubing and piping.
Fatigue of Stainless Steel in Simulated Operational Conditions: Effects of PWR Water, Temperature and Holds
Authors: Solin Jussi , Reese Sven , Karabaki H. Ertugrul , Mayinger Wolfgang
Published: November 2014

Our experimental research on fatigue performance of stainless steels and transferability of laboratory data to plant operational conditions focuses in niobium stabilized stainless steel (1.4550, X6CrNiNb1810mod) taken from a pipe manufactured as primary piping for a German NPP Good fatigue performance both in air and in PWR water was reported in previous PVP papers.

The NUREG/CR-6909 report proposes Fen factors based on stroke controlled experiments in hot water for non-stabilized steels. Since PVP2013-97500 we have new data in 200°C PWR water to compare with predictions by NUREG/CR-6909. Our strain controlled tests in 325°C and 200°C PWR water give longer lives resp. smaller Fen factors. For the slowest tested strain rate 4·10−6 in 325°C water the prediction according to NUREG/CR-6909 goes just below the current ASME design curve, but our results remains well above. Including also the relevant design temperature effect, our result Fen = 4 is well below the predicted Fen = 14,5. The gap is smaller for higher strain rates and low Fen values.

Simplified simulations of fatigue transients combined with normal operation indicated that relevant loading patterns as hold-time effects may result to notably longer lives than in standard laboratory tests. A concern was raised on transferability of data to thermal transients separated with months of normal operation. Cyclic strain (transients) followed by hot holds (normal operation) lead to time and temperature dependent hardening with reduction in cyclic plastic strain and fatigue usage, i.e. extension of life.

This paper reports new data, challenges met and our progress towards developing realistic design factors for effects both reducing and extending fatigue endurance in nuclear power plant operational conditions.
Residual Stresses in Friction Stir Welded Tube-Tubesheet Joint
Authors: Al-Badour Fadi A. , Merah Nesar , Shuaib Abdelrahman , Bazoune Abdelaziz
Published: November 2014

In this paper, a 3-D thermo-mechanical finite element model (FEM) is developed to simulate the process of friction stir seal welding (FSSealW) of tube-tubesheet joint, using a commercial finite element (FE) package considering temperature dependent material properties. The model is used for the prediction of temperature and stress distributions, as well as the prediction of the residual stresses in the seal welded joint, including the expanded tube and surrounding ligaments. Validation of the model is achieved using experimental temperature measurements. The FEM results are found to be in good agreement with experimental ones. Temperatures of the joint material away from the processed zone are below the annealing temperature. The calculated residual stresses are found to be compressive and help to enhance the contact stress in the tube-tubesheet joint.
Presentation of the 2014 Revisions to the RCC-M Code
Authors: Malouines Philippe
Published: November 2014

The paper describes the general approach followed by AFCEN, the French Society for Codified Rules for Design, Construction and In-Service Inspection of Nuclear Island Components, from the technical and organizational points of view. The RCC-M code, reissued in 2012 and modified with addenda in 2013 and 2014, is presented. The main new topics of activity of the RCC-M Subcommittee are considered: conformity with regulation(s), use of International Standards, equivalence with other codes and harmonization, and new requirements for the quality management system.

The paper highlights how industrial experience is currently being integrated into the RCC-M code, and how the code is evolving to take into account the enlargement of the AFCEN Membership, new AFCEN organization rules, and the international environment, and best practices. The processes for dealing with requests for modifications and interpretations are described.
Tensile- and Fatigue-Properties of Low Alloy Steel JIS-SCM435 and Carbon Steel JIS-SM490B in 115 MPA Hydrogen Gas
Authors: Matsunaga Hisao , Yoshikawa Michio , Itoga Hisatake , Yamabe Junichiro , Hamada Shigeru , Matsuoka Saburo
Published: November 2014

Slow strain rate tests using smooth specimens of two types of steels, low alloy steel JIS-SCM435 and carbon steel JIS-SM490B, were carried out in nitrogen gas and hydrogen gas under a pressure of 115 MPa at three different temperatures: 233 K, room temperature and 393 K. In nitrogen gas, these steels exhibited the so-called cup-and-cone fracture at every temperature. On the other hand, in hydrogen gas, in both steels a number of cracks initiated on the specimen surface and coalesced with each other at every temperature, which led to a marked reduction in ductility. Nonetheless, even in hydrogen gas, JIS-SCM435 exhibited a certain reduction of area after the stress-displacement curve reached the tensile strength (TS), whereas JIS-SM490B exhibited little, if any, necking in hydrogen gas. In addition, tension-compression fatigue testing at room temperature revealed that in both steels there was no noticeable difference between the fatigue strengths in air and 115MPa hydrogen gas, especially in a relatively long life regime. Considering that there was little or no hydrogen-induced degradation in either TS or fatigue strength in JIS-SCM435, it is suggested that JIS-SCM435 is eligible for fatigue limit design on the basis of a safety factor (i.e. TS divided by the allowable design stress) for mechanical components used in hydrogen gas up to 115 MPa.
Estimates of J and COD for Complex-Cracked Pipes Based on FE Analyses and ERS Method
Authors: Jeong Jae-Uk , Choi Jae-Boong , Huh Nam-Su , Kim Yun-Jae
Published: November 2014

A complex crack can occur at the dissimilar metal weld parts of nuclear pipes due to stress corrosion cracking. The fracture behavior of such crack is different with those of a simple through-wall crack. Thus, the engineering estimation equations for predicting the fracture mechanics parameters, i.e. crack opening displacement and J-integral, should be newly provided in order to evaluate the leak-before-break of pipe including complex cracks.

In the previous research, an engineering scheme using reduced thickness analogy was suggested to calculate the crack opening displacement and J-integral for complex cracked pipes. However, this method has limitations in the sense that a through-wall crack is assumed to be developed only in the circumferential direction, and the effect of crack closure cannot be considered. Another scheme for complex cracked pipes is the enhanced reference stress method considering crack closure effect by suggesting the optimized reference load for complex crack geometry. It presented the more accurate results compared to previous engineering estimation scheme. However, an elastic component of crack opening displacement and J-integral were calculated by assuming the crack shape as the simple through-wall crack due to the absence of engineering solutions for complex-cracked pipes.

In this context, finite element based evaluation of fracture parameters was performed to confirm the validation of previous estimation schemes. Moreover, the variations of crack opening displacement and J-integral according to a change of surface crack depth ratio of complex crack are systematically investigated based on detailed 3-D finite element analyses. Furthermore, enhanced reference stress method considering finite element based elastic values from the complex-cracked pipe models is assessed to overcome the limitation of previous enhanced reference stress approach.
Present Status and Periodical Inspection of Large Capacity Cylinders for Tube Trailers in China
Authors: Li Wei , Deng Guide , Ji Fang , Zhang Junpeng , Zhao Jirui
Published: November 2014

Tube trailers with large capacity seamless steel cylinders have been used more and more widely in China to transport industrial gases. As an authorized tube trailer inspection organization by the government of China, China Special Equipment Inspection and Research Institute has carried out periodical inspection of tube trailers in China since 2004. A statistical analysis was done based on 4059 periodical inspection reports of tube trailers from 2004 to 2013, which include 3687 tube trailers and 31627 cylinders. Information of present status of tube trailers in China was obtained, such as annual amounts, usage regions of tube trailers, numbers of cylinders mounted on tube trailers, and specifications, filling mediums, typical flaws of the cylinders. The statistical results show that mounting threads of 16.16% of the cylinders were worn seriously, and repair or reprocess work had to be done on these threads. Reasons of the abrasion of the mounting threads were analyzed and discussed by taking into account the usage regions of the tube trailers, the detailed structures of the mounting threads, and the mounting location of cylinders on the tube trailers.
Determination of Updated Fatigue Properties of PE 4710 Cell Classification 445574C High Density Polyethylene
Authors: Adams Timothy M. , Nickholds Shawn , Munson Douglas , Andrasik Jeffery
Published: November 2014

For corroded piping in low temperature systems, such as service water systems in nuclear power plants, replacement of carbon steel piping with high density polyethylene (HDPE) is a cost-effective solution. Polyethylene pipe can be installed at much lower labor costs that carbon steel pipe and HDPE pipe has a much greater resistance to corrosion. The ASME Boiler and Pressure Vessel Code, Section III, Division 1 currently permits the use of non-metallic piping in buried safety Class 3 piping systems. Additionally, HDPE pipe has been successfully used in non-safety-related systems in nuclear power facilities and is commonly used in other industries such as water mains and natural gas pipelines. This report presents the results of updated fatigue testing of PE 4710 cell classification 445574C pipe compliant with the specific Code requirements. This information was developed to support and provide a strong technical basis for material properties of HDPE pipe for use in ASME Boiler and Pressure Vessel Code, Section III New Construction and Section XI repair or replacement activities. The data may also be useful for applications of HDPE pipe in commercial electric power generation facilities and chemical, process and waste water plants via its possible use in the B31 series piping codes. The report provides fatigue data in the form of Code S-N curves for fusion butt joints in PE 4710 cell classification 445574C HDPE pipe.
An FEA Investigation Into Ratchetting Induced Purely by Cyclic Thermal Loading
Authors: Campbell Conor S. , Mackenzie Donald
Published: November 2014

A detailed finite element investigation of the cyclic elastic-plastic response of three model structures subject to thermal and mechanical loading is presented within the context of ASME B&PV Code Section VIII Division 2 design requirements. The model structures are a thin tube subject to constant internal pressure and a cyclic through-thickness linear temperature gradient (the Bree problem), a three bar system subject to cyclic thermal loading only and an intermediate thickness tube subject to internal pressure and an axially moving cyclic temperature wave. Incremental elastic-plastic finite element analysis assuming an elastic-perfectly-plastic material model and small deformation theory is performed for each model structure and ratchet and shakedown boundaries determined by application of a bisection method. Results are compared with ASME VIII ratcheting assessment procedures. The results show that in the Bree problem ratcheting does not occur under thermal loading alone, as expected, however for the two other sample structures it is shown that ratchetting can occur under thermal loading for structures subject to specific deformation constraints. The lead author is an MS level student at the University of Strathclyde.
Study on the Mechanical Behavior of Aluminum Alloy 5083 Friction Stir Welded Joint
Authors: Mourad A-H. I. , Allam M. , El Domiaty A.
Published: November 2014

The mechanical behavior of friction stir welded joints made of aluminum alloy 5083-H111 was studied in this investigation. Different welding processes parameters (rotational speeds, travelling speeds and tool pin shapes) were used to investigate the effect of process parameters on the strength and fracture properties of the joint. Scanning electron microscopy and optical microscopy analysis were conducted to study the effect of friction stir welding FSW process on the grain size in the welding zones. In general, the results illustrated that tool profile, the rotation speed and the traveling speed has great effect on the strength of the welded joint. Scanning electron microscopy and optical microscopy investigations showed that the grains inside the welding zone was refined and equiaxed resulting in higher hardness inside the nugget.
On the Effectiveness of Two Isolation Systems for the Seismic Protection of Elevated Tanks
Authors: Paolacci Fabrizio
Published: November 2014

This paper deals with the effectiveness of two isolation system for the seismic protection of elevated steel storage tanks. In particular the performance of High Damping Rubber Bearings and Friction Pendulum isolators has been analyzed. As case study an emblematic example of elevated tanks collapsed during the Koaceli Earthquake in 1999 at Habas Pharmaceutics plant in Turkey has been considered. A time-history analysis conducted using lumped mass models demonstrated the high demand in terms of base shear required to the support columns and their inevitable collapse due to the insufficient shear strength. A proper design of HDRB and FPS isolator and a complete non-linear analysis of the isolated tanks proved the high effectiveness of both isolation systems in reducing the response of the case tank. Actually, a reduced level of displacements of isolators and a reduced level of convective base shear obtained with the second isolation typology, suggested the used of FPS isolators rather than HDRB.
Unsteady Aerodynamic Forces Measured on a Fluttering Profile
Authors: Zolotarev Igor , Vlček Václav , Kozánek Jan
Published: November 2014

The study presents evaluation of optical measurements of the air flow field near the fluttering profile NACA0015 with two-degrees of freedom, Mach number of the flutter occurrence were M=0.21 and M=0.45. Aerodynamic forces (drag and lift components) were evaluated independently on the upper and lower surfaces of the profile. Using the mentioned decomposition, the new information about mechanism of flutter properties was obtained. The forces on the upper and lower surfaces are phase shifted and are partially eliminated as a result of the circulation around the profile. The cycle changes of these forces cause the permanent energy contribution from the airflow to the vibrating system.
Probeless Tool Aided Friction Stir Welding as a Fabrication Technique for Tungsten Embedded Mechanical Composite of Copper
Authors: Ahuja Yogita , Ibrahim Raafat , Paradowska Anna , Riley Daniel
Published: November 2014

Friction stir welding (FSW) is a relatively new solid state metallurgical joining technique. It flourishes on the simple principle of utilising frictional heat by the stirring motion of a non-consumable rotating tool to create the seam. Feasibility of FSW aided by a newly designed probeless tool was investigated for fabricating copper-tungsten mechanical composite. The most effective parameter combination was determined by conducting a parametric study of the probeless tool aided FSW copper. Strength of the mechanical composite fabricated at this condition was evaluated through punch shear testing. Punch shear testing established that the friction stir welded interface of the copper-tungsten composite was 87% as strong as the base metal (i.e. copper). Advantages of the designed technique have been summarised.
Investigation of Characteristic of Flow Induced Vibration Caused by Turbulence Relating to Acoustically Induced Vibration
Authors: Nishiguchi Masato , Izuchi Hisao , Minorikawa Gaku
Published: November 2014

In the flare piping system, it is known that piping vibrations occur caused by Acoustically Induced Vibration (AIV) and Flow Induced Vibration (FIV) corresponding to high flow rate, high pressure drop and relatively thin pipe wall thickness. For FIV, turbulence generated at combining tee with high fluid velocity results in low frequency piping vibration. For AIV, large noise produced through a component with large pressure drop results in high frequency piping vibration. Carucci and Mueller shows the several cases with piping failure due to AIV and most of these cases the piping failure occurred at the combining tee. In these piping failure cases, the velocity at the combining tee would be quite high close or equal to sound speed and this means piping vibrations could occur due to FIV in addition to AIV.

This paper shows the investigation results of FIV at combining tee with 90 degrees using experimental data. The results are compared to the previous study results for 45 degrees combining tee and the difference between 90 and 45 degrees tees are discussed in the view points of pressure fluctuation and piping vibration. This paper also shows that the vibration index proposed by authors is quite effective to evaluate the vibration level caused by FIV for both of 90 and 45 degrees tees. This proposed vibration index is applied to failure and no failure cases presented in Carucci and Mueller paper with some assumptions and it is suggested that the vibration indexes for failure case is relatively higher than those of no failure cases. And this suggests that not only AIV but also FIV could affect the piping failure reported in Carucci and Mueller paper.
Verification Analyses for Newly Developed Automatic 3D Finite Element Crack Propagation System
Authors: Doi Hiroaki , Nakamura Hitoshi , Gu Wenwei , Shim Do-Jun , Wilkowski Gery
Published: November 2014

In order to calculate the crack propagation in complicated-shaped locations in components such as weld in penetration structures of reactor pressure vessel of nuclear power plants, an automatic 3D finite element crack propagation system (CRACK-FEM) has been developed by the Nuclear Regulation Authority (NRA, Japan). To confirm the accuracy and effectiveness of this analysis system, a verification analysis was performed. The program used for comparison is PipeFracCAE developed by Engineering Mechanics Corporation of Columbus, which has been used for many crack propagation analyses in various applications. In this paper, the axial crack propagation analysis for primary water stress corrosion cracking (PWSCC) in a steam generator inlet nozzle of a pressurized water reactor (PWR) plant is presented. The results demonstrate that the two codes are in good agreement.

The contents of this paper were conducted as a research project of the Japan Nuclear Energy Safety Organization (JNES) when one of the authors (Doi) belongs to JNES. After this project, JNES was abolished and its staff and task were absorbed into NRA on March 1, 2014.
Manufacture Trial of Tensile and Compressive Creep Test Machine Both for Plate-Type Specimen and Round-Bar Specimen
Authors: Funai Madoka , Watanabe Osamu , Matsuda Akihiro
Published: November 2014

This paper shows the concepts for creep test machine. Designed creep machine can be used for tensile dead loading or compressive dead loading for the specimens of plate-type and round-bar types. Applied temperature is up to 1000°C. The developed creep test machine can be applied under the action of dead loading, so that long time measurement is possible. The firm measurement stock shelf is used as the framework of keeping right angle maintenance. The obtained creep test machine is also expected to have the rigidity of long term use. The necessary devises are for general purpose to reduce the cost.
Ultrasonic Inspection of Large Diameter Polyethylene Pipe Used in Nuclear Power Plant
Authors: Shi Jianfeng , Hou Dongsheng , Guo Weican , Zhou Yaoda , Chen Xia , Zheng Jinyang
Published: November 2014

Polyethylene (PE) pipe has many advantages such as good flexibility, corrosion resistance and long service life. It has been introduced into nuclear power plants for transportation of cooling water both in U.S. and Europe. Recently, one Chinese nuclear power plant in Zhejiang Province also introduced four polyethylene pipelines in essential cooling water system with operating pressure of 0.6MPa and operating temperature of no more than 60°C. The PE pipes used in this nuclear power plant are DN762 SDR9 (30in OD, 3.3in wall), which are much larger and thicker than traditional natural gas PE pipe. As the pipe wall is so thick that the ultrasonic phased array instrument used in inspection of PE pipe with diameter less than 400mm has been improved. Results of field inspection in the Sanmen nuclear plant are reported, and the presented ultrasonic inspection technique proves to be effective for high density polyethylene (HDPE) pipe of large size in nuclear power plant.
Periodic Materials-Based 3D Seismic Base Isolators for Nuclear Power Plants
Authors: Yan Y. , Laskar A. , Cheng Z. , Menq F. , Tang Y. , Mo Y. L. , Shi Z.
Published: November 2014

The concept of periodic materials, based on solid state physics theory, is applied to earthquake engineering. The periodic material is a material which possesses distinct characteristics that do not allow waves with certain frequencies to be transmitted through; therefore, this material can be used in structural foundations to block unwanted seismic waves with certain frequencies. The frequency band of periodic material that can filter out waves is called the band gap, and the structural foundation made of periodic material is referred to as the periodic foundation. In designing a periodic foundation, the first step is to match band gaps of the periodic foundation with the natural frequencies of the superstructure. This is an iterative process. Starting with a design of the periodic foundation, the band gaps are identified by performing finite element analyses using ABAQUS. This design process is repeated until the band gaps match natural frequencies of the superstructure, and the field tests of a scaled specimen are conducted to validate the design. This is an on-going research project. Presented in this paper are the preliminary results, which show that the three dimensional periodic foundation is a promising and effective way to mitigate structural damage caused by earthquake excitations.
Advances in NDE of DM Welds From RPV ID
Authors: Thigpen B. A. , Glass S. W.
Published: November 2014

In Pressurized Water Reactors (PWRs), the similar and dissimilar welds joining the reactor pressure vessel (RPV) nozzles to the main coolant piping have normally been volumetrically examined as part of the full 10-year RPV inspection. Generally due to access challenges to the outside diameter (OD) surface, these examinations have been performed from the component inside diameter (ID) surface. In the US and for many plants around the world, these welds fall under the requirements of the ASME B&PV Code Section XI, Appendix VIII performance demonstration as mandated by the applicable safety authority, requiring blind demonstration of detection and sizing accuracy on known defects. Many in-service inspection (ISI) vendors have qualified themselves for ID these examinations under the EPRI Appendix VIII Performance Demonstration (PD) program since it’s initiation in the early 2000s, but examination of the wavy surface DM welds and field welds (closure welds) has been a challenge for virtually all vendors to achieve the target 0.125″ RMS depth sizing error. This has been managed by assuming a larger depth sizing error corresponding to whatever the vendor’s PD assessed error was should an indication be found that required accurate sizing to justify continued plant operation. Moreover, vendors have been reluctant to re-qualify their systems as new tools have immerged due to the high associated cost.

Equipment obsolescence and an interest to apply the latest technology prompted AREVA to undertake a re-qualification for these welds. This has allowed use of more advanced phased array techniques with 3-D wavy surface compensation. In addition, a new nozzle examination tool, NEMO has been developed. Such a tool is particularly suitable for plants where the nozzles must be examined on their 10 year or shorter interval schedule but where the vessel examination can be deferred to 20 years. This paper discusses the detection and sizing advances for these wavy surface DM welds as well as the first deployment of the NEMO tool.
Pressure Variation in Low Pressure Side of Shell and Tube Heat Exchanger After Tube Rupture
Authors: Katke Ganesh S. , Venkatesh M. , Gulhane N. P.
Published: November 2014

This paper presents an analytical algorithm to determine the pressure variation on the Low Pressure side of a Shell and Tube Heat Exchanger (STHE) after a tube rupture and its validation using CFD simulation. STHEs are often used for exchanging heat between high-pressure (HP) and low-pressure (LP) fluids in the chemical process industry. In case tube rupture occurs in a STHE having a large pressure difference between HP and LP side, there is a risk of release of significant quantity of fluid from the HP side to the LP side. The consequent pressure build-up can lead to the failure of LP side pressure envelope. Generally, design pressure of the LP side is about 10–20% higher than the operating pressure of the LP side fluid, but well below the operating pressure on the HP side. There is no well-established methodology to design the LP side to withstand sudden release of high pressure fluid following a tube rupture. Three dimensional analyses were carried out using Computational Fluid Dynamics to study the pressure variation in LP side (shell side) of a Gas Cooler and to validate the results obtained from the analytical algorithm. It has been observed that the pressure on the LP side exceeds the design pressure instantaneously due to generation of a pressure pulse after tube rupture. This may lead to damage of LP envelope (shell) and internal structure of STHE.
Masses of Fluid Contributing to Rocking Motion of Cylindrical Tanks With Partial Uplift of Bottom Plate
Authors: Taniguchi Tomoyo , Katayama Yukihiro
Published: November 2014

Accurate and easy calculation of the mass of fluid contributing to the rocking motion of cylindrical tanks with partial uplift of bottom plate, which is the effective mass of fluid for rocking motion, that for rocking-bulging interaction, effective moment inertia of fluid for rocking motion and their centroid, is proposed. Asymmetric deformation of the tank bottom plate due to crescent-like uplift is used to put quantification of the masses away from rigorous treatments. This study considers the cylindrical tank as a set of thin rectangular tanks, so-called a slice model, and puts them perpendicular to the rotational axis of the tank rock motion. Then solve a boundary-value problem of each slice model specified by uplift of the tank bottom plate and its location, the mass of fluid contributing to rocking of cylindrical tanks is quantified as the sum of that of each slice model. Values of the effective mass of fluid for rocking motion, that for rocking-bulging interaction, effective moment inertia of fluid for rocking motion and their centroid are tabulated and depicted as a function of the aspect of tanks for different values of the ratio of the uplift width of the tank bottom plate to the diameter of tank.
A Case Study of Evaluation of Tank Rock Motion With Simplified Analysis Procedure
Authors: Taniguchi Tomoyo , Okui Daisuke
Published: November 2014

Based on mechanical analogy between rocking motion of cylindrical tanks and that of two degree of freedom (2DOF) system, equations of motion for cylindrical tanks allowed to rock, that naturally includes effects of rocking-bulging interaction, are derived. Employing that the tank bulging motion is specified by a value of response acceleration spectrum in the absence of uplift and ordering terms, the simplified analysis for evaluating the angular acceleration of the tank rock motion, absolute maximum response acceleration of the tank bulging motion, base shear and reaction is derived. Assuming two percent of the ratio of the uplift width of the tank bottom plate to the diameter of tank, all physical quantities used for the simplified analysis are determined, tank responses are calculated and compared with corresponding responses computed by the Explicit Finite Element Analysis (EFEA). Comparison suggests that the proposed simplified analysis conservatively estimates all responses besides the angular acceleration.