bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling and Simulation of Conical Bending With Cylindrical Rolls
Authors: Feng Zhengkun , Champliaud Henri , Dao Thien-My
Published: August 2009

Conical roll bending with noncompatible conical rolls is less expensive than that with compatible conical rolls. However, the process still can not adapt to all desired cone radii and the manufacturing of such rolls is more expensive than that of cylindrical rolls. This paper presents the modeling of conical roll bending with cylindrical rolls, in which the sliding of the rolls over the plate section is allowed. Investigations of the influence of the sliding on the bending quality are carried out. Numerical simulations based on finite element method are performed with commercial software ANSYS LS-DYNA. The results agree well with those obtained with noncompatible and compatible conical rolls.
An Improvement in the Code Evaluation of Flawed Pipes
Authors: Smith Amy J. , Dwivedy Keshab K.
Published: August 2009

ASME Code Section XI Nonmandatory Appendix C [1] formalized evaluation of flaws in piping for justification of continued service of piping components with an identified crack-like flaw. The revision of this appendix in 2004 was a significant improvement in the evaluation methodology for both flawed austenitic stainless steel and ferritic steel pipe depending upon the failure mode governed by limit load (fully plastic), elastic-plastic fracture mechanics, or linear elastic fracture mechanics. The appendix also provides a screening procedure to determine failure mechanism and a procedure for flaw modeling based on the estimated flaw size at the end of a specified evaluation period. The purpose of this paper is to propose an improvement to the limit load method applicable to screened-in carbon steel, wrought stainless steel base material, stainless steel weld material with nonflux weld, and cast products in which the ferrite content is less than twenty percent. In addition, changes in the formulation are proposed to extend the methodology to non-crack-like flaws. Both crack-like and non-crack-like circumferential flaws in the piping are analyzed to simplify formulation for flaw evaluation. The paper concludes that the proposed formulation improves efficiency of the application of Appendix C methodology for crack-like flaw and non-crack-like flaw evaluations.
Evaluation of Controlling Transient Ramp Times Using Piping Methodologies When Considering Environmental Fatigue (Fen) Effects
Authors: Davis J. Michael , Stevens Gary L.
Published: August 2009

As a part of the 2006 ASME Code support being provided by the Materials Reliability Program (MRP) Fatigue Issue Task Group (ITG), and later the Technical Support Committee (TSC), it is desired to develop a solution that establishes the most severe transient for design purposes when environmental fatigue rules are considered. This problem does not have an obvious answer, since the environmental fatigue multiplier (e.g., Fen) expressions depend on the strain rate during a transient. The strain rate in a thermal transient is dependent on the ramp time of the temperature change. Classically, fatigue analysis has been performed by conservatively considering that temperature changes are instantaneous (e.g., ramp time = zero). This results in maximizing the stress response. But, all other things being equal, Fen effects are minimum at instantaneous changes. Previous work performed by the MRP to support 2005 ASME Code activities has investigated how Fen × Usage varies with ramp time and has concluded that Fen × Usage maximizes at a small but definitely non-zero ramp time [1]. The implications of non-zero transient ramp times are that difficulties arise in both specifying ahead of time and qualifying the component for appropriate ramp times and, at the same time, not creating a situation whereby plant operations are required to proceed at a specified pace to remain design compliant. Therefore, it is desirable to have the qualifying fatigue analyses cover all conceivable ramp times such that the operator neither has to: (a) be limited to a minimum pace, nor (b) confirm through observations that the pace is at least as fast as assumed in the design. This paper summarizes qualifying fatigue analyses that have been performed using piping methodologies to define bounding ramp times for a variety of piping geometry and material configurations. The intent of these analyses is to provide the component designer with a set of parametric tools that can be used to easily design components without the need for iterative fatigue analyses to determine the bounding conditions when Fen rules are considered. In addition, the tool developed to perform the parametric analyses is available for future use by the designer should more specific analyses be required.
Sample Environmental Fatigue Calculations Associated With the Review of Draft Regulatory Guide DG-1144
Authors: Stevens Gary L. , Davis J. Michael , Spain Les
Published: August 2009

Draft Regulatory Guide DG-1144 “Guidelines for Evaluating Fatigue Analyses Incorporating the Life Reduction of Metal Components Due to the Effects of the Light-Water Reactor Environment for New Reactors”, July 2006 [1], and Associated Basis Draft Document NUREG/CR-6909 (ANL-06/08), “Effect of LWR Coolant Environments on the Fatigue Life of Reactor Materials”, July 2006 [6] provided methods for addressing environmentally assisted fatigue (EAF) in all new nuclear plant designs. In these documents, a new model was proposed that more accurately accounts for actual plant conditions. The new model includes an EAF correction factor, Fen, which is different from Fen methods previously and currently being considered for adoption into the ASME Code. The Fen methods proposed in DG-1144 are also different than the Fen methods utilized by license renewal applicants, as required by the Generic Aging Lessons Learned (GALL) report [2], as documented in NUREG/CR-5704 [4] (for stainless steel) and NUREG/CR-6583 [3] (for carbon and low alloy steels).
Finite Element Ductile Failure Simulations of Tensile and Bend Bars Made of API X65 Steels
Authors: Kim Yun-Jae , Oh Chang-Kyun , Song Tae-Kwang , Shim Do-Jun
Published: August 2009

This paper presents a micro-mechanical model of ductile fracture for the API X65 steel using the Gurson-Tvergaard-Needleman (GTN) model. Experimental tests and FE damage simulations using the GTN model are performed for smooth and notched tensile bars, from which the parameters in the GTN model are calibrated. As application, the developed GTN model is applied to simulate small-sized, single-edge-cracked tensile and bend bars, via three-dimensional FE damage analyses. Comparison with experimental test data shows overall good agreements.
Net-Section Limit Pressure and Engineering J Estimates for Axial Part-Through Surface Cracked Pipes
Authors: Kim Yun-Jae , Oh Chang-Sik , Song Tae-Kwang
Published: August 2009

This paper provides net-section limit pressures and a reference stress based J estimation method for pipes with internal axial surface cracks under internal pressure. Based on systematic small strain FE limit analyses using elastic-perfectly plastic materials, closed-form approximations of net-section limit pressures are presented. Then, based on proposed net-section limit moments, a method to estimate elastic-plastic J is proposed based on the reference stress approach. Comparison with extensive FE results shows overall good agreement.
Interaction Effect of Twin Circumferential Surface Cracks on Limit Load of Pipe Under Tension
Authors: Kamaya Masayuki
Published: August 2009

The influence of interaction between two surface cracks on the limit load (LL) was examined by finitie element analysis. The cicumferential surface cracks were assumed to be on the straight pipe that was subjected to uniform tensile load. Change in the LL due to relative spacing of cracks, crack and pipe geometries were evaluated. The LL was equivalent to coalesced crack when the cracks were on the same plane or their offset and horizonatal distance were the same, although the LL decreased as the offset distance increased in the other cases. The magnitude of the interaction was large compared with that of the stress intensity factor and J-integral value under the same relative spacing. Based on the analysis results, assessment criteria for evaluating the influence of the interaction was discussed.
Axial Length and Shape Effects of Local Wall Thinning on Net-Section Limit Loads
Authors: Park Chi-Yong , Lee Sung-Ho , Kim Yun-Jae , Oh Chang-Kyun , Myeng No-Hoon
Published: August 2009

This paper provides plastic limit loads of pipes with local wall thinning under internal pressure and under bending, by quantifying effects of the axial extent and the shape of local wall thinning. The effect of the axial extent on plastic limit loads is not so significant for bending but could be more significant for internal pressure. It is also found that the effect of the shape of local wall thinning on limit loads could be quite significant. Thus idealization of local wall thinning as rectangular shapes rather than circular ones could lead to significantly conservative estimates of maximum loads, which is also supported by comparison with published full-scale pipe test data.
Effects of the Bend Angle and the Length of the Attached Straight Pipe on Plastic Loads for Pipe Bends
Authors: Oh Chang-Sik , Kim Yun-Jae
Published: August 2009

This paper quantifies effects of the bend angle and the length of the attached straight pipe on plastic limit loads of the 90° pipe bend, based on small strain FE limit analyses using elastic-perfectly plastic materials with the small geometry change option. It is found that the effect of the length of the attached straight pipe on plastic limit loads can be significant, and the limit loads tend to decrease with decrease of the length of the attached straight pipe. Regarding the effect of the bend angle, it is found the plastic load smoothly changes from the limit load of the straight pipe when the bend angle approaches zero to the plastic load of the 90° pipe bend when the bend angle approaches 90 degree.
Incorporation of Unit 1 Inspection Results on the STP Reactor Vessel Head Nuclear Asset Management Analysis
Authors: Kee Ernie , Moiseytseva Vera , Galenko Alexander , Morton David , Popova Elmira
Published: August 2009

Including local experience information with generic data can maximize operational flexibility and help make better informed nuclear asset management decisions. Experience data are particularly helpful in risk-informed asset management decision-making. In 2004, South Texas Project (STP) used a risk-informed study to help decide the proper timing for reactor vessel head replacement. The decision to replace the reactor vessel heads was based on a previous study. Up to the time of decision-making inspections had not been performed at STP and therefore, the likelihood of finding a J-Groove failure in an inspection was based on generic industry information in both of the studies. In the Unit 1 fall outage, a full volumetric reactor vessel head penetration inspection was performed. The inspection method is briefly described. The algorithm for optimal timing of the reactor vessel head is presented and solved for the STP case. The generic industry J-Groove failure data is updated with the recent results from the Unit 1 outage inspection and the new failure projections are summarized. The optimal timing model is again run using the updated data and compared with the previous results.
Fatigue Life of Commercial High Pressure Needle Valves and Tee Assemblies
Authors: Rovere Mario L. , Mann Michael D. , Culley William R.
Published: August 2009

This paper investigates the design cycle life of commercially available 9/16 inch needle valves and 9/16 inch tees under tri-axial fatigue. The valves and tees investigated were manufactured from 316 stainless steel and are rated to 4100 bar (60,000 psi) maximum allowable working pressure. The testing was performed using a tri-axial fatigue machine originally designed by Dr. B. Crossland, Dr. J.L.M. Morrison and Dr. J.S.C. Perry in 1960 [1] and upgraded by Michael D. Mann of KMT Waterjet Systems, Inc. This investigation compares the fatigue life of the 9/16 inch needle valves and 9/16 inch tees from two different commercial sources via actual test results from the fatigue machine.
Buckling of Axisymmetric Cylindrical Shells of Variable Thickness: Finite Difference Solution
Authors: Brar Gurinder Singh , Hari Yogeshwar , Williams Dennis K.
Published: August 2009

This paper presents the third of a series of solutions to the buckling of imperfect cylindrical shells subjected to an axial compressive load. In particular, the initial problem reviewed is the case of a homogeneous cylindrical shell of variable thickness that is of an axisymmetric nature. The equilibrium equations as first introduced by Donnell over seventy years ago are discussed and reviewed in establishing a basis for embarking upon a solution that utilizes finite difference methods to solve the resulting equilibrium and compatibility equations. The ultimate objective of these calculations is to achieve a quantitative assessment of the critical buckling load considering the small axisymmetric deviations from the nominal cylindrical shell wall thickness. Clearly in practice, large diameter, thin wall shells of revolution that form stacks are never fabricated with constant diameters and thicknesses over the entire length of the assembly. The method and results described herein are in stark contrast to the “knockdown factor” approach currently utilized in ASME Code Case 2286-1. The results obtained by finite difference method agree well with those published by Elishakoff and Williams for the prediction of buckling load.
AWJ Performance Characteristics at 600 MPa
Authors: Hashish Mohamed
Published: August 2009

Increasing the pressure of abrasive waterjet, while fixing the jet power, increases the jet’s power density and thus the cutting speed may increase. This was observed for steel, aluminum, and stone cutting. It was also observed that the kerf taper is less for higher pressure jets. Increasing the pressure while keeping the jet diameter fixed will increase both the power and the power density. This will result in increase cutting speed and less taper. The operating cost of the AWJ process consists mainly of the costs of abrasives, nozzle wear, utility, and maintenance of equipment. The cost per unit length of material (specific cost) is determined based on the cutting speed. It was found that the main advantage of increasing pressure is increasing the cutting speed or reducing the abrasive consumption per unit time or unit length of cut. The highest savings are obtained when the speed is maximized by increasing the pressure and the abrasive flow rate. Several study cases were addressed in this paper using assumptions and simple models to generalize the analysis. The analysis indicates that increasing the pressure from 400 MPa to 600 MPa may result in cost per unit length saving of over 30%.
Limitations of ASME Section VIII Division 3 Pressure Vessels Designed to Non-Mandatory Appendix J
Authors: Peters Daniel T. , Bernosky Matthew
Published: August 2009

ASME Section VIII Division 3 2006 Addenda [2] has adopted Non-Mandatory Appendix J “Stress Concentration Factors for Cross-Bores in Closed-End Cylinders and Square Blocks”. There were a number of concerns relative to the proposal that required further research. These included a reduction in margin against collapse in some designs, a possible effect in the cyclic life of the vessels due to the plasticity at the intersection of the cross-bore, and the possible increased strain due to both the cross-bore and the potential blend radii. This paper is an attempt to analyze these effects and make recommendation with regard to possibly limiting the range of concentration factors that should be included in the Code.
CFD Simulations of Natural Convection/Radiation Heat Transfer Within the Fuel Regions of a Truck Cask for Normal Transport
Authors: Venigalla Venkata V. R. , Greiner Miles
Published: August 2009

A two-dimensional finite volume mesh is constructed that accurately represents the geometry of a legal weight truck cask, including four PWR fuel assemblies inside. CFD simulations calculate buoyancy driven gas motion as well as natural convection and radiation heat transfer in the gas filled fuel regions. They also calculate conduction within the cask solid components. The cask is in a normal transportation environment. The fuel and cask temperatures are calculated for ranges of fuel heat generation rate and cladding emissivity, for both helium and nitrogen backfill gas. The cask thermal capacity, which is the fuel heat generation rate that brings the peak fuel cladding to its temperature limit, is also determined. The results are compared to simulations in which the gas speed is set to zero, to determine the effect of buoyancy induced motion. The allowable heat generation rate is 23% higher for helium than for nitrogen due to helium’s higher thermal conductivity. Increasing the cladding emissivity by 10% increases the allowed fuel heating rate by 4% for nitrogen, but only 2% for helium. The higher value for nitrogen is caused by the larger fraction of heat transported by radiation when it is the backfill gas compared to helium. The stagnant-gas calculations give only slightly higher cladding temperatures than the gas-motion simulations. This is because buoyancy induced gas motion does not greatly enhance heat transfer compared to conduction and radiation for this configuration. The cask thermal capacity from the stagnant-CFD calculation is therefore essentially the same as that from the CFD simulation. This suggests that future cask thermal calculations may not need to include gas motion. These results must be experimentally benchmarked before the CFD methods can be used with confidence for designing transport casks. Basket surface temperatures calculated in this work can be used as the basis for boundary condition in those experiments.
Buckling of Ring Stiffened Pontoons of Floating Roofs in Aboveground Oil Storage Tanks
Authors: Yoshida Shoichi , Kitamura Kazuhiro
Published: August 2009

The 2003 Tokachi-Oki earthquake caused severe damage to oil storage tanks due to liquid sloshing. Six single-deck floating roofs had experienced structural problems as evidenced by sinking failure in large diameter tanks at the refinery in Tomakomai, Japan. The pontoon of floating roof might be buckled due to circumferential bending moment during the sloshing. The content in the tank was spilled on the floating roof from small failures which might be caused in the lap-welded joints or in the stress concentrated parts of the pontoon bottom plate by the buckling. Then the floating roof began to lose buoyancy and submerged into the content slowly. The failure of the roof expanded gradually in the sinking process. It is presumed that the initial small failures were caused by the elastic buckling of the pontoon due to circumferential bending moment. In this paper, the buckling strength of the pontoon is presented using axisymmetric shell finite element analysis. Linear elastic bifurcation buckling analyses are carried out and the buckling characteristics of ring stiffened pontoons are investigated.
A Study on the Cylindrical Shock Compression Device Using Shock Wave Generated by Explosion of Explosive
Authors: Nakamyosu Megumi , Kim Young Kook , Tanaka Shigeru , Itoh Shigeru
Published: August 2009

There are a lot of studies related to the shock wave generated by explosive; explosive compaction [1], explosive welding [2], shock synthesis [3], and explosive forming [4]. Especially, shock synthesis is interested. Recently, the artificially diamond with high-function material using shock synthesis method is being studied. In this paper, to obtain an Al/Graphite and Cu/Graphite consolidated bulk material, shock compaction method is employed. Experiments are carried out using a cylindrical shock compression device. The samples are Al/Graphite and Cu/Graphite powder. In these experiments, the pressure which acts on powder container was not high because as a X-ray diffraction result, a peak of diamond was not appeared in any cases. However, the consolidated material of Al/Graphite and Cu/Graphite are obtained.
The Research on Molding Super-Hard Material Powder Using Shock Compaction
Authors: Kida Junichi , Tanaka Shigeru , Hokamoto Kazuyuki , Itoh Shigeru
Published: August 2009

Shock compaction techniques have been developed in order to create new advanced materials with improved and unique properties. The problem in industrializing the technique is the formation of cracks due to the propagation of strong shock wave inside the material to be consolidated and a size limitation for recovered compact. Therefore, we developed a modified apparatus to employ cylindrical configuration. The tungsten carbide is used for a lot of tools by the peculiar mechanical properties. A lot of time is needed for the manufacturing though the solid of the super-hard alloy like the tungsten carbide is manufactured by sintering usually. So we tried shock compaction to make bulk materials of hard-to-consolidate powders using cylindrical configuration. Using the cylindrical configuration, shock compaction experiment was carried out for consolidation of WC-15wt%Co powders. Look of compacted exactly were observed for a sample recovered. High compaction hardness was also measured for the sample. Numerical simulation was carried out using LS-DYNA3D and compared with the experimental result for the WC-15wt%Co compacts.
Measurement of Residual Stresses in a Nozzle-to-Cylinder Weld After Thermal Ageing at 550°C
Authors: Hossain S. , Truman C. E. , Smith D. J. , Bouchard P. J.
Published: August 2009

This paper presents results from a programme of experimental measurements of residual stresses in a type 316H stainless steel component consisting of a nozzle welded to a cylinder. The residual stresses were measured using the deep-hole drilling (DHD) technique. The welded component had been thermally aged in a furnace at 550°C for 19,644 hours prior to the residual stress measurements. Measurements were obtained in the through-thickness section of the component at two locations: (i) in the cylinder heat affected zone (HAZ) at the flank of the nozzle-to-cylinder weld intersection and (ii) in the cylinder HAZ near the crown of the nozzle-to-cylinder weld intersection. The stress measurements made after the furnace heat soak treatment are compared with the earlier as-welded stress measurements. In comparison with as-welded residual stress measurements on the same component and with residual stresses in a service-aged (55,000 hours at 525°C) component, it was evident that the thermal soak test treatment had significantly relaxed the weld residual stresses. In particular the soak test hoop stress profile was almost identical to the service-aged condition, whereas the transverse stress distribution had only been partially relaxed by the thermal soak test.
Statistical Analysis of Residual Stresses in a Stainless Steel Edge Welded Beam
Authors: Nadri Brahim , Bouchard Peter J. , Truman Christopher E. , Smith David J.
Published: August 2009

A statistical approach based on Bayes’ theorem has been applied to determine the ‘best estimate’ means of two sets of measured residual stress profiles at various point locations through the depth of a stainless steel edge welded beam. Residual stresses introduced into an AISI Type 316H stainless steel beam (250mm × 50mm × 10mm) by welding along the 10mm edge have been measured using high energy synchrotron and neutron diffraction techniques. Mean values of measured residual stresses are compared with predicted stresses obtained from a two-dimensional finite element simulation employing isotropic, kinematic and mixed isotropic-kinematic hardening models. The accuracy of the prediction has been assessed using a root mean square error approach (RMS).
Coupled Thermo-Mechanical Modelling of Friction Stir Welding
Authors: Li Hongjun , Mackenzie Donald
Published: August 2009

The significant development in welding technology for the last decade is the emergence of Friction Stir Welding (FSW). This paper investigates the thermo-mechanical phenomena involved in the FSW welded plates by Finite Element Analysis. The numerical models are fully thermo-mechanically coupled in that heat generated by material plastic deformation and temperature dependent mechanical material properties are taken into account. The whole FSW process is divided into three distinct stages: plunge, dwell and transverse. The transient temperature, stress and velocity of material particles around the tool are reported from the numerical models. It is found that temperature plays an important role in obtaining a sound weld, and only when a proper temperature field is established can the FSW process proceed to next stage. It is also found that it is not possible to fully simulate the FSW process using the ALE formulation without full remeshing during the travel stage of the process due to excessive element distortion.
Deterministic and Probabilistic Analyses of Pipeline Burst Failure
Authors: Zhu Xian-Kui , Leis Brian N.
Published: August 2009

Deterministic and probabilistic analyses are carried out in this paper to investigate burst failure of defect-free pipelines. Three deterministic models for predicting the burst pressure of pipelines, i.e., the Tresca solution, the Mises solution and a newly developed Average Shear Stress Yield (ASSY) solution are used in statistical evaluation of experimental data of burst pressure, and in probabilistic analysis of pipeline failure. Monte Carlo simulation is adopted and programmed as Excel macros for calculating probability of failure. The results show that the ASSY solution is the best prediction of the experimental data, the Tresca and Mises solutions provide a lower bound and an upper bound, respectively. These three theoretical solutions can significantly affect the possibility of burst failure for pipelines, and the difference can be in several orders of magnitude. Validity of the modified ASME B31G and other criteria to predict the burst failure is examined, and influence of the probability distribution type of random variables on probability of failure for pipelines is also discussed.
Progress With the International Pipe Failure Data Exchange Project
Authors: Lydell Bengt , Huerta Alejandro , Gott Karen
Published: August 2009

Certain member countries of the Organisation for Economic Cooperation and Development (OECD) in 2002 established the OECD Pipe Failure Data Exchange Project (OPDE) to produce an international database on the piping service experience applicable to commercial nuclear power plants. OPDE is operated under the umbrella of the OECD Nuclear Energy Agency (NEA). The Project collects pipe failure data including service-induced wall thinning, part through-wall crack, pinhole leak, leak, and rupture/severance (i.e., events involving large leak rates up to and beyond the make-up capacity of engineered safeguards systems). The part through-wall events include degradation in excess of code allowable for pipe wall thinning or crack depth. OPDE also addresses such degradation that could have generic implications regarding the reliability of in-service inspection. At the end of 2006 the OPDE database included approximately 3,700 records on pipe failure affecting ASME Code Class 1 through 3 and non-Code piping. This paper summarizes the unique data quality considerations that are associated with the reporting and recording of piping component degradation and failure. The paper also summarizes the database content and puts it in perspective relative to past efforts to systematically collect and evaluate service experience data on piping performance.
The Probability of Pipe Failure on the Basis of Operating Experience
Authors: Lydell Bengt
Published: August 2009

This paper addresses the progress with piping reliability analysis methods and techniques in the context of probabilistic safety assessment (PSA) to support risk-informed decisions. Piping reliability analysis has been a topic of discussion and concern within the nuclear safety community for a very long time. In part, this concern has been related to the capabilities and limitations of available methods and techniques, as well as with the requirements for how to best perform quantitative analysis in support of safety cases. The team of analysts responsible for the seminal Reactor Safety Study (WASH-1400) performed a limited evaluation of nuclear power plant piping reliability based on service experience from the then approximately 150 U.S. commercial nuclear reactor operating years [1,2]. This evaluation was aimed at estimation of loss-of-coolant-accident (LOCA) frequencies for input to the two PSA models of WASH-1400. After the publication of WASH-1400 in 1975 many other R&D projects have explored the roles of structural reliability models and statistical evaluation models in providing acceptable input to PSA. Furthermore, during the past 15 years efforts have been directed towards establishment of comprehensive pipe failure event databases as a foundation for exploratory research to better understand the capabilities and limitations of today’s piping reliability analysis frameworks. Against a historical overview of past efforts, this paper addresses the question how to best utilize service experience data for quantitative piping reliability analysis. Significant progress has been made to develop pipe failure databases, as well as analysis methods and techniques to explore and analyze the body of service experience with piping from today’s (February 2007) over 12,500 commercial reactor operating years. Insights from recent pipe failure database applications are utilized to reach some conclusions about the capability of statistical analysis approaches to piping reliability analysis, including Bayesian modeling.
Erosive Wear of Sharp-Edged Orifice Plates
Authors: Ezekoye L. I.
Published: August 2009

Sharp-edged orifice plates are extensively used in flow measurement and flow trimming. In many plant applications where they are used, orifices are installed in systems which are generally clean and debris free. However, there are applications where the system may be either debris laden or exposed, in accident conditions, to debris that could challenge the effectiveness of orifices. This paper presents the results of an accelerated erosive wear test of aluminum and steel orifice plates to determine firstly, how sharp-edged orifices wear in such medium, and secondly, how the wear affects flow measurements.
Certification of DOT 7A Type A Packaging in Type AF Configurations
Authors: Liu Yung , Liaw Jay , Li Zhian , Shuler James
Published: August 2009

Based on the U.S. Department of Transportation (DOT) regulations in 49 CFR 173.7(d), the U.S. Department of Energy (DOE) Order 460.1B (DOE 2003) codifies the authority of certification of Type-B and fissile material transportation packaging to the Office of Environmental Management (EM), except for materials of interest to national security, naval propulsion systems, and civilian radioactive waste management. DOE Order 460.1B also stipulates that the EM certification of Type B and fissile materials transportation packaging shall be in accordance with the U.S. Nuclear Regulatory Commission (NRC) safety standards in 10 CFR Part 71. The Packaging Certification Program (PCP) of the Office of Safety Management and Operations (EM-60) is supported by technical review teams at Argonne National Laboratory and Lawrence Livermore National Laboratory. In recent years EM-60 has received requests for certification of fissile material packages for the shipment of low-enrichment uranium oxides in DOT 7A Type A drums in Type AF configurations. One request originally sought for DOT exemption (i.e., special permit) per 49 CFR 107, Subpart B that underwent reviews by DOE, NRC, and DOT. DOT eventually advised DOE that the packaging should be certified as a DOT 7A Type A drums in a Type AF configuration. Historically EM-60 has also issued Certificate of Compliances (CoC) for low-enrichment fissile uranium metals in wooden boxes as Type B packages for shipment, even though the wooden boxes do not meet the structural and thermal requirements in 10 CFR 71 under hypothetical accident conditions. There are also provisions in 10 CFR 71.15 for exemption from classification as fissile material, and in 10 CFR 71.22 General license: Fissile material that specifically references the DOT requirements in 49 CFR 173.417(a) for Type A package. The myriad of NRC and DOT regulations applicable to fissile materials and Type A packages availed alternative approaches in the requests for packaging certification; however, in all cases the primary concern for fissile material packages is the assurance of criticality safety in the shipment under both normal conditions of transport and hypothetical accidents. This paper will present a case in the certification of DOT 7A Type A packaging in Type AF configurations, drawing highlights from a recent certification review of packagings for shipment of low-enrichment uranium oxides in Type A drums. Various regulatory requirements are also discussed.
Validation and Development of Fitness-for-Service Assessment Procedures for Local Thin Areas in API RP579
Authors: Janelle J. L. , Osage David A.
Published: August 2009

The procedures in API 579 [1] provide computational methods to assess flaws that are found in in-service equipment caused by various damage mechanisms. The focus of this study is to review the technical basis for the fitness-for-service assessment procedures for general and local metal loss. Extensive validation of these procedures along with additional development is presented. The conclusions of the study are recommended as the best practices to be included in API 579.
Weld Residual Stresses and Primary Water Stress Corrosion Cracking in Bimetal Nuclear Pipe Welds
Authors: Brust Frederick W. , Scott Paul M.
Published: August 2009

There have been incidents recently where cracking has been observed in the bi-metallic welds that join the hot leg to the reactor pressure vessel nozzle. The hot leg pipes are typically large diameter, thick wall pipes. Typically, an inconel weld metal is used to join the ferritic pressure vessel steel to the stainless steel pipe. The cracking, mainly confined to the inconel weld metal, is caused by corrosion mechanisms. Tensile weld residual stresses, in addition to service loads, contribute to PWSCC (Primary Water Stress Corrosion Cracking) crack growth. In addition to the large diameter hot leg pipe, cracking in other piping components of different sizes has been observed. For instance, surge lines and spray line cracking has been observed that has been attributed to this degradation mechanism. Here we present some models which are used to predict the PWSCC behavior in nuclear piping. This includes weld model solutions of bimetal pipe welds along with an example calculation of PWSCC crack growth in a hot leg. Risk based considerations are also discussed.
Demonstration Results of the Robotized Repair of Underclad Cracks in the Main Vessel
Authors: Delaunay Bastien , Tortolano Marcel , Guillet Jacques
Published: August 2009

The increase in nuclear power plants lifetime is a major issue for EDF. But the subsequent ageing of main components requires new maintenance strategy development especially for the reactor pressure vessel. The R&D division of the French electricity company EDF is working on robotized repairing feasibility. This approach can be more relevant than the replacement of components or the development of dedicated machines for costs, delays and dosimetry reasons. In this context, EDF R&D has engaged a feasibility demonstration of robotized controls and repairs of underclad cracks in this vessel. Stable underclad cracks in the main vessel have been known for many years. Anticipating the ageing of components, EDF R&D is currently running a full repairing feasibility demonstration. The complete repair consists in installing a robot dedicated to the carrying out of the following processes: • Precise localization of the defects using UT testing, • Elimination of the defects by high speed machining, • Control that the defects were eliminated using penetrant testing, • Geometry recording of the removed volume by laser scanning, • Weld metal refilling of the cavity with TIG tempered bead process, • UT control of the repair. Two main repairing strategies have been developed. The first one consisted in removing the defect without refilling. This option simplifies the repairing operation but requires extra justifications on corrosion created by the contact between carbon steel and primary circuit water. The second option with all the processes developed above provides a complete protection against corrosion but presents specific issues mainly coming from welding without pre and post heat-treatment. The welding procedure and the mechanical and metallurgical substantiation of the complete repair have been developed in 2005. The main work carried out in 2006 consisted in developing high speed machining and UT control procedures and in measuring some mechanical parameters resulting from this repair. The complete repair demonstration including all of the complementary processes (positioning and localization of the arm at the beginning of the repair, penetrant testing, video inspections, laser scanning) was performed on a mock-up at the beginning of 2007.
Finite Element Analyses of JNES/NUPEC Seismic Shear Wall Cyclic and Shaking Table Test Data
Authors: Xu Jim , Nie Jinsuo , Hofmayer Charles , Ali Syed
Published: August 2009

This paper describes a finite element analysis to predict the JNES/NUPEC cyclic and shaking table RC shear wall test data, as part of a collaborative agreement between the U.S. NRC and JNES to study seismic issues important to the safe operation of commercial nuclear power plant (NPP) structures, systems and components (SSC). The analyses described in this paper were performed using ANACAP reinforced concrete models. The paper describes the ANACAP analysis models and discusses the analysis comparisons with the test data. The ANACAP capability for modeling nonlinear cyclic characteristics of reinforced concrete shear wall structures was confirmed by the close comparisons between the ANACAP analysis results and the JNES/NUPEC cyclic test data. Reasonable agreement between the analysis results and the test data was demonstrated for the hysteresis loops and the shear force orbits, in terms of both the overall shape and the cycle-to-cycle comparisons. The ANACAP simulation analysis of the JNES/NUPEC shaking table test was also performed, which demonstrated that the ANACAP dynamic analysis with concrete material model is able to capture the progressive degrading behavior of the shear wall as indicated from the test data. The ANACAP analysis also predicted the incipient failure of the shear wall, reasonably close to the actual failure declared for the test specimen. In summary, the analyses of the JNES/NUPEC cyclic and shaking table RC shear wall tests presented in this paper have demonstrated the state-of-the-art analysis capability for determining the seismic capacity of RC shear wall structures.
Asset Management Evaluation: Extended Pilot Case Studies
Authors: Hai¨k P. , Bauby C. , Lonchampt J. , Remy E.
Published: August 2009

The long term management of a production asset raises several major issues among which rank the technical management of the plant, its economics and the fleet level perspective one has to adopt. Decision makers are therefore faced with the need to define long term policies (up to the end of asset operation) which take into account multiple criteria including safety (which is paramount) and performance. In this paper we first remind the reader of the EDF three-level methodology for asset management. As introduced in PVP 03 [1] and PVP 04 [2], this methodology addresses the component/technical level (how to safely operate daily and invest for the future), the plant level (how to translate technical decisions into plant-wide consequences including economic performance) and the fleet level (how to manage a large number of similar assets). We then focus on the software tools — introduced in PVP 04 [2] and PVP 05 [4] — that implement this methodology in order to allow decision makers to define, evaluate and analyze long term plant operation and maintenance policies. Lastly we show how the methodology and the software tool were used, in 2006, on two pilot case studies. Examples of technical and economic results obtained at the plant level are described as well as the conclusions one can draw from them in order to help decision makers evaluate and analyze long term asset management strategies or compare different plants. We also analyze the added value of probabilistic evaluations and of our “rolling-up” process that allows to take into account interactions existing between the components of the plant. Finally, we introduce some of the possible uses of our methodology and tools.
“Adaptative” User Interface for Expert Knowledge Validation and Evaluations Interpretation in an Asset Management Process
Authors: Hai¨k P. , Parfouru S. , Bauby C. , Mahe S.
Published: August 2009

The long term management of a production asset raises several major issues among which rank the technical management of the plant, its economics and the fleet level perspective one has to adopt. Decision makers are therefore faced with the need to define long term policies (up to the end of asset operation) which take into account multiple criteria including safety (which is paramount) and performance. In this paper we first remind the reader of the EDF three-level methodology for asset management. We then focus on the knowledge model and on the software tools that implement this methodology in order to gather, preserve, share, maintain and exploit the expert knowledge needed for asset management and to allow decision makers to define, evaluate and analyze long term plant operation and maintenance policies. Lastly, as the quality of the processed plant level evaluations (operation & maintenance strategies are evaluated, at a plantlevel, through a set of technical and economic indicators) and their interpretation relies on the quality of the knowledge captured in the tools, we focus on the definition of a “adaptative” user interface — based on Electronic Structured Documents — that allows technical/strategic experts and decision makers to consult the useful pieces of knowledge in a context dependent way. Such an interface, which, in a near future, should be fully implemented in the tools will facilitate the validation of the knowledge-base content and the analysis of the processed results.
Linear and Nonlinear Finite Element Analysis of an Exhaust Manifold With Included Bellows
Authors: Steinbrink Scott E. , Aggarwal Mahesh C. , Shepherd Kapilla I. M.
Published: August 2009

The aim of this paper is to examine the utility of nonlinear analysis for structural response to thermal and mechanical loads, for a structure containing alternating regions of high and low stiffness as a result of inclusion of bellow sections. Utility is measured by comparison of results of linear and nonlinear analyses. The specific example used is that of an exhaust manifold for a large diesel engine. The paper discusses modeling of geometric and material nonlinearity, and makes recommendations in regard to which nonlinear effects are thought to be significant, based on the linear/nonlinear comparisons. The paper also contains general comments on the finite element modeling of structures containing bellows.
Evaluation of the Failure of a Radioactive Waste Transfer Line Jacket
Authors: Wiersma Bruce J. , Subramanian Karthik H. , Jenkins Charles F. , Hinz William R. , Fellinger Andrew P. , Plummer A. Scott
Published: August 2009

Radioactive wastes are confined in 49 underground storage tanks at the Savannah River Site. The waste is transported between tanks primarily via an underground transfer piping system. Due to the hazardous nature of the waste, the inner core stainless steel pipe is typically surrounded by a carbon steel pipe jacket, which provides secondary containment. Recently, several through-wall penetrations were discovered on a segment of one of the jackets. An evaluation was performed to verify the failure mechanism and to estimate the degree of damage that existed on the pipe segment. Failure analysis confirmed that pitting corrosion on the exterior of the pipe led to the through-wall penetration. Ultrasonic measurements were utilized to determine the remaining wall thickness in adjacent areas of the pipe. Based on these measurements, the degree of pitting and general corrosion was determined. Pit growth rate models were then developed to estimate the life expectancy of sections of the pipe that had not been excavated. The calculations indicated that the occurrence of through-wall penetrations in this jacket will begin to increase substantially in 12 years. Given that this pipe segment will be utilized beyond this time, short-term and long-term solutions to this failure were proposed. The short-term solutions focused on the repair or replace decisions that must be made to return the jacket to service as soon as practical. The long-term solutions focused on a broader strategy to address jacket integrity issues in the entire waste storage facility. These solutions included the evaluation of innovative remote inspection and repair techniques.
Z-Factor for Ferritic Pipe Axial Flaw Using J-T Analysis
Authors: Hoang Phuong H. , Scarth Douglas A.
Published: August 2009

Tabulation solution for ductile tearing failure of piping axial flaws was first implemented in the A90 Addendum to the 1989 Edition of the ASME B&PV, Section XI, Appendix H. The solution was based on J-Tearing analyses of pipe axial semi-elliptical part-through wall flaws in a generic ferritic material that has J1C > = 600 in-lbs/in2. Analytical solution for pipe axial flaw has not been implemented in the Code. In this paper a general load multiflier Z-factor is developed for use in an analytical solution for pipe axial part-through wall flaw, which is compatible with the current Elastic-Plastic Fracture Mechanics (EPFM) tabular solution in the Section XI, Appendix C. The Z-curve is developed using the same J-Tearing analysis technique and the same generic material properties for ferritic materials that were used in the development of the Code tabulation solutions. The predicted failure stresses using the Z curve are fairly corelated and conservatively the actual failure stress in the available test specimens from the PIFRAC database.
Type B Radioactive Material Package Failure Modes and Contents Compliance
Authors: Hensel S. J. , Watkins R. W. , Smith A. C.
Published: August 2009

Type B radioactive material package failures can occur due to any one of the following: inadequate design, manufacture, and maintenance of packages, load conditions beyond those anticipated in the regulations, and improper package loading and operation. The rigorous package design evaluations performed in the certification process, robust package manufacture quality assurance programs, and demanding load conditions prescribed in the regulations are all well established. This paper focuses on the operational aspects of Type B package loading with respect to an overbatch, a condition not evaluated during packaging certification, which may cause a package failure.