bluuebunny/crossref_metadata_2025 huggingface dataset:
Certification of SAFESHIELD 2999A
Authors: Liu Yung , Bellamy Steve , Shuler James
Published: July 2008

Based on the U.S. Department of Transportation regulations in 49 CFR 173.7(d), the U.S. Department of Energy (DOE) Order 460.1B 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 safety standards in 10 CFR Part 71. The Office of Licensing (EM-24) is supported by technical review teams at Argonne National Laboratory, Lawrence Livermore National Laboratory, and Savannah River National Laboratory. SAFESHIELD 2999A is a Type-B radioactive material transportation packaging designed for use by the DOE’s Isotope Program. The contents of the packaging consist of source capsules of Co-60, Cs-137, or Ir-192; solid and liquid-metal accelerator targets; ion exchange resins; and target processing wastes. No fissile materials are included. Protection against radiation and confinement of radioactivity are, therefore, the two major requirements for the safety performance of the SAFESHIELD 2999A packaging under both normal conditions of transport and hypothetical accidents. The Safety Analysis Report for Packaging (SARP) of SAFESHIELD 2999A underwent four revisions by the applicant during the entire certification review. This paper will highlight some of the technical issues in areas such as contents, shielding, and quality assurance, and will discuss how these issues interact and affect other areas such as structural, thermal, containment, operating procedures, and acceptance tests and maintenance. Also discussed in the paper is the use of an independent third party to facilitate resolution of the technical issues and move the process forward for certification of SAFESHIELD 2999A.
Evolution of New Gasket Type Increases Reliability in HF Alkylation Unit
Authors: Simonton Julie L. , Barry Leon K.
Published: July 2008

The evolution of a new gasket type for use in Hydrofluoric (HF) Alkylation Units from the standard HF alkylation spiral-wound type gasket, (Monel windings, PTFE filler, and outer carbon steel ring) to a more specialized and robust gasket type was driven by a need to minimize flange face corrosion, overcome handling limitations and improve sealing performance. Protecting the carbon steel flange face from aggressive HF acid corrosion and resulting iron fluoride scaling, while increasing both the reliability and sealability of an HF connection was achieved, preventing costly flange damage, potential leakage and associated unit shutdowns required for repairs. This paper highlights the journey taken by a major petrochemical company in determining the solution to improving gasket durability and leakage prevention, while significantly reducing flange face corrosion in their HF alkylation units.
The Safe Transport of Radioactive Material: Principles and Their Application in the United Kingdom
Authors: Morgan-Warren Edmund J.
Published: July 2008

The good safety record of the transport of radioactive materials owes much to the establishment at an early stage of the principles which have been enshrined in the IAEA’s regulations and their supporting guidance material. These have been reviewed and updated periodically since their introduction in 1961. This paper outlines the principles governing the safe transport of radioactive material and their implementation through the regulatory regime. Beginning with a brief consideration of the scope and challenges of radioactive material transport, the paper outlines the basic principles of safety in transport, and the regulatory mechanism. The basis for packaging standards is described in relation to quantities, specific activities and release rates. The several types of package are discussed and the performance and testing requirements for each are summarised. Operational and administrative requirements are considered, including pre-shipment checks, contamination and radiation limits, and marking and labelling requirements. The paper includes a discussion of the requirements for emergency arrangements and a brief account of how these are fulfilled, and concludes with a description on the role of the competent authority in overseeing the regulatory process.
Deformation-Induced Microstructure Effects on Ultrasonic Waves: Simple Shear Versus Pure Shear
Authors: Tang S. H. , Wu S.
Published: July 2008

Although similar in total strain in simple shear and pure shear, they are very diverse in deformation modes, and the effect of these deformation modes on ultrasonic waves is very different. This paper aims to investigate deformation-induced microstructures and their effects on ultrasonic waves under simple and pure shear states. Texture evolutions, plastic spins, point defects induced by cross slips and fractal dimensions are analyzed via finite element polycrystal model. The investigation indicates that the texture evolutions are the same and transverse wave velocities depend on textures mainly; however, the point defects induced by cross slips show a striking difference between simple shear and pure shear, this implies that longitudinal wave velocities are sensitively influenced by point defects during plastic deformation.
The Industry Commitment to Global Transport Safety Standards
Authors: Green Lorne
Published: July 2008

Standards and regulations have no intrinsic practical effect without taking into account those who are the object of them; standards and regulations do not become operationally effective until they are implemented by the entities which are subject to them. Accordingly, there is a necessary synergy between the regulator and the regulated — the regulators whose task it is to make and enforce the rules for safe, efficient and reliable transport, and those whose job it is to transport within the rules. The bottom line of transport safety regulation is safety, but safety is not a factor exclusively of the working of regulatory provisions. Stability, clarity and consistency in the international regulatory regime also are important to safety. The experience of the nuclear transport industry operating within the regulations has been positive. The issues which have arisen have related principally to differences in interpretation of the regulations by modal organisations and competent authorities coupled with different time schedules for implementation. Such differences take on added importance in the context of an accelerated two-year review cycle. It is the operators who have the experience of dealing with the international regulatory regime across jurisdictions. The periodic review of the international transport safety regime is important, but it may be that such review could be more fully informed by a sharing of experiences. Does a periodic review have of necessity to require proposals for change, or rather, shouldn’t such proposals flow from a review first, and then be advanced if deemed appropriate on the basis of the review? It is important to show confidence in a regulatory regime that has proven its effectiveness over several decades. All stakeholders to the regime benefit from stability. This paper will examine industry’s experience of operating within the two-year regulatory review process and present some suggestions for consideration. If industry is to be persuasive in urging greater regulatory harmonisation worldwide, it must work to develop consolidated industry positions on practical issues which it then can carry to the other stakeholders for consideration. This paper will cite specific examples of industry, within WNTI, working to develop such consolidated views.
The New European Flange Design Method: Theory, Advantages, Comparison With Taylor Forge and DIN — Future Developments
Authors: Lidonnici Fernando
Published: July 2008

All the national standards dealing with Flange Design are generally based either on the Taylor Forge or on the DIN 2505 method. The assumptions used in both methods are more or less the same, that is, two different bolt loads are calculated separately for two different conditions: first the load at bolting-up, necessary for the seating of the gasket, and then the load needed to obtain leak tightness in service. In this way the flange calculation is made for two independent conditions, bolting-up and service (plus possibly a hydrostatic test condition), with no relationships with each other. However a bolted joint is a complex structure composed by two (possibly different) flanges, the gasket and the bolting; the bolt load varies from one condition to another as a consequence of the initial bolt tightening and of the elastoplastic (and creep) behaviour of all the interconnected components. The European Standard EN 1591 [1] has developed, for the first time, a method based on a more complex model of the bolted assembly. The method has been further developed in Annex G of EN 13445 Part 3 [2] (the European Unfired Pressure Vessel Standard), which is now under revision following to the results of experiments, also considering the different behaviour of liquids and gases from the point of view of leak tightness. The intention of this paper is not to explain in detail the theory used by EN 1591, but simply to describe the principles on which the method is based, and to compare the results of its use as an alternative to the other methods in a series of practical examples.
A Numerical Model of the Crystallization of Pure Aluminium
Authors: Kavicka Frantisek , Stetina Josef , Stransky Karel , Sekanina Bohumil , Dobrovska Jana , Heger Jaromir
Published: July 2008

The model was originally designed to confirm and enhance the capabilities of experimental research in the crystallization of pure aluminium (99.99% Al), specifically to determine the zone of the occurrence of columnar and equiaxed crystals and the positions of the transition interface. The character of primary crystallization was investigated on a simple cylindrical sample, crystallizing in a cast-iron mould pre-heated to various temperatures. The experimental research comprised the measurement of temperatures using thermocouples, the evaluation of the experimentally acquired temperature gradients G, and the shift rate of the phase transition interface R. The numerical model had been developed to expand the limited experimental capabilities of the evaluation of G and R to every point of the longitudinal section, based on the investigation of the 3D transient temperature field within the system comprising the casting, the mould and ambient. This enabled the prediction of the character of the crystallization in greater detail.
Measurement of Bolt Clamping Forces by Electromagnetic Vibration Method Without Disassembling Bolted Joints
Authors: Fukuoka Toshimichi , Sugano Nobukuni
Published: July 2008

The integrity and safety of a bolted joint can be greatly guaranteed by applying and maintaining an appropriate amount of bolt preloads. However, the variation of bolt preloads inevitably occurs in the service condition due to various reasons, even if the initial bolt preloads are properly applied. Accordingly, the monitoring of bolt forces in the service condition is significantly important. From the practical point of view, it is preferably conducted without disassembling the objective bolted joint. In this paper, Electromagnetic Vibration Method is introduced for monitoring the variation of bolt preloads in the service condition, and its performance is examined by experiments using bolted joints with various geometric configurations. Electromagnetic Vibration Method estimates the magnitude of bolt preload by measuring the resonant frequencies of the bolted joint, which vary in accordance with the contact pressure of the joint interface. From the experimental studies, Electromagnetic Vibration Method was found to be effective to evaluate the bolt force with a reasonable accuracy, except for the bolted joint whose plate interface being under very high contact pressure.
Determination of MAWP of a Slab Tank Using FEA
Authors: Hari Yogeshwar
Published: July 2008

The objective of this paper is to determine the maximum allowable working pressure per ASME Code [1] of a slab tank using finite element analysis [2]. The slab tank is to store various criticality liquids used in today’s industry. The slab tank has been designed on the basis of the capacity of the stored liquids. The slab tank design is consists of (a) two long side members, (b) two short side members, (c) top head, and (d) bottom head. The slab tank is supported from the bottom at a height by a rectangular plate enclosure. The heads are designed for internal pressure and static pressure at the bottom where the pressure is the maximum. The slab tank has been designed to withstand internal pressure plus static pressure due to liquid head. The procedure used to determine MAWP is as follows: (1) The dimensioned slab tank is modeled using STAAD III finite element software. (2) Two loading conditions are used: (a) internal pressure; (b) static pressure due to liquid head; (c) combined internal pressure plus static pressure. The maximum stress and deflection is evaluated at the above three conditions for determination of MAWP. The stress due to the static pressure due to liquid will remain the same. Only the stress due to internal pressure can be changed by changing the internal pressure. New internal pressure is calculated to meet the ASME code stress criteria, which then will be the MAWP condition. A procedure is established to determine the MAWP of slab tanks using FEA.
Numerical Assessment of Pipe Effort in Large Deformed Areas
Authors: Blyukher Boris , Malachowski Jerzy , Niezgoda Tadeusz , Szurgott Piotr
Published: July 2008

The results of numerical simulations of some selected states of loading the pipelines within the non-linear range, with account taken of large displacements and deformations, are described in this paper. Numerical analyses resulted in sizes of deformations, strains and stresses, which further on were used to conduct comparative analysis with results effected by tests carried out on a testing stand under laboratory conditions. At points where the pipeline is supported with pipe bearers, various kinds of dents, folds, ovalisations of the pipeline’s cross-section may occur so that results of numerical simulations enable evaluation of deformation sizes in a real pipeline structure.
Revised and New Proposal of Environmental Fatigue Life Correction Factor (Fen) for Carbon and Low-Alloy Steels and Nickel Base Alloys in LWR Water Environments
Authors: Higuchi Makoto , Sakaguchi Katsumi , Hirano Akihiko , Nomura Yuichiro
Published: July 2008

Low cycle fatigue life of carbon and low alloy steels reduces remarkably as functions of strain rate, temperature, dissolved oxygen and sulfur in steel in high temperature water simulating LWR coolant. A model for predicting such fatigue life reduction was first proposed in the early 1980s and since then has been revised several times. The existing model established in 2000 is used for the MITI Guideline [6] and the TENPES Guideline [7] which stipulate procedures for evaluating environmental fatigue damage at LWR plants in Japan. This paper presents the most recent environmental fatigue evaluation model derived based on additional fatigue data provided by the EFT Project over the past five years. This model differs not significantly with previous version but does provide more accurate equations for the susceptibility of fatigue life to sulfur in steel, strain rate, temperature and dissolved oxygen. Test data on environmental fatigue of nickel base alloys are available only to a limited extent and there is yet no model for predicting fatigue life reduction in such an environment. The EFT Project has made available considerable environmental fatigue test data and developed a new model for calculating Fen of nickel base alloys. The contribution of environment to fatigue of nickel base alloy is much less compared to that in austenitic stainless steel.
Weather Seal Design for Pipe Flanges
Authors: Kikuchi Tsutomu , Ogiso Ryoji
Published: July 2008

A weather seal is constructed in order to prevent the risk of high temperature flanges leaking during rain, for example, due to a temperature difference between the flanges and their bolts. From the point of view of saving energy, an adequate scal is essential to reduce the amount of heat that dissipates from the flange. However, the better the seal makes the greater the bolt temperature increase, and hence, the higher the risk of leakage. Thus there is a great demand for an optimal seal design.
Effect of Tightening Speed on the Torque-Tension and Wear Pattern in Bolted Connections
Authors: Nassar Sayed A. , Ranganathan Ramanathan M. , Ganeshmurthy Saravanan , Barber Gary C.
Published: July 2008

This experimental study investigates the effect of tightening speed and coating on both the torque – tension relationship and wear pattern in threaded fastener applications. The fastener torque – tension relationship is highly sensitive to normal variations in the coefficients of friction between threads and between the turning head and the surface of the joint. Hence, the initial level of the joint clamp load and the overall integrity and reliability of a bolted assembly is significantly influenced by the friction coefficients. The effect of repeated tightening and loosening is also investigated using M12, Class 8.8, fasteners with and without zinc coating. The torque – tension relationship is examined in terms of the non-dimensional nut factor K. The wear pattern is examined by monitoring the changes in surface roughness using a WYKO optical profiler and by using a LECO optical microscope. A Hitachi S-3200N Scanning Electron Microscope (SEM) is used to examine the contact surfaces, under the fastener head, after each tightening/loosening cycle. Experimental data on the effect of variables and the tightening speed, fastener coating and repeated tightening on the nut factor are presented and analyzed for M8 and M12, class 8.8, fasteners.
Measurements of Thermal Properties of Gaskets for the Design of Bolted Flange Joints Under Thermal Conduction Conditions
Authors: Ohmura Takahiro , Hanashima Kanji , Nyumura Junichi , Sawa Toshiyuki
Published: July 2008

In this study, the thermal properties of the gaskets, which were used for designing the bolted flange joints, such as effective thermal conductivity, specific heat, linear thermal expansion coefficient and so on were measured. Especially, the effective thermal conductivities were measured by using the heat flow method. The relationship between the gasket structure and the thickness was shown by using an equivalent thermal resistance, and an empirical equation of effective thermal conductivity, which was related to the bulk density and absolute temperature, was proposed by deriving the heat conduction in solid, radiation and gas. Also, in the measurement of the linear thermal expansion coefficients of the gaskets, the measured values were shown to change substantially below 150 °C, and to depend on the heating rate and the load applied on the gasket sample.
Effect of Factors on Fatigue Life in PWR Water Environment
Authors: Sakaguchi Katsumi , Nomura Yuichiro , Suzuki Shigeki , Tsutsumi Kazuya , Kanasaki Hiroshi , Higuchi Makoto
Published: July 2008

It is known that the fatigue life in elevated temperature water is substantially reduced compared with that in the air (1–4). Although the key parameters that have an effect on fatigue lives are strain rate and temperature in PWR water environment, it is necessary to consider the other factors on fatigue life for accurate evaluation. The effects of many factors on fatigue life have been investigated experimentally in the EFT project of Japan Nuclear Energy Safety Organization (JNES). Many tests have been done for carbon, low alloy, stainless steel and nickel-based alloy, and the environmental fatigue life equation that evaluates quantitative factor influencing the fatigue life has been proposed. In this paper, in order to evaluate effects of material structure difference between base metal and weld metal, strain amplitude, strain rate, strain ratio, temperature, sulfur content in steel, aging, water flow rate and strain holding, fatigue tests were performed in simulated PWR water environment.
Fatigue Crack Growth Curve for Austenitic Stainless Steels in PWR Environment
Authors: Nomura Yuichiro , Sakaguchi Katsumi , Kanasaki Hiroshi , Suzuki Shigeki
Published: July 2008

Reference fatigue crack growth rate curves for austenitic stainless steels in pressurized water reactors (PWR) environments were prescribed in JSME S NA1-2004(1) in Japan. The reference fatigue crack growth curve in PWR environment had been determined as a function of stress intensity factor range, temperature, load rising time and stress ratio. In order to confirm the applicability of the reference fatigue crack growth rate curve under high stress ratio, low rising time and low stress intensity range, fatigue crack propagation tests of austenitic stainless steels 316, 316 weld metal, 304 and 304 weld metal were carried out. It is concluded that the reference fatigue crack growth curve in PWR environment is applicable to predict fatigue crack growth rate of this study test conditions.
Establishing Minimum Pressurization Temperature (MPT) for Heavy Wall Reactors in Hydroprocessing Units
Authors: McLaughlin James E.
Published: July 2008

A procedure was developed to establish the minimum pressurization temperature (MPT) for Cr-Mo reactor vessels greater than 2-inches thick in high temperature hydrogen service. The procedure is consistent with a Level 2 assessment as defined in Part 3 of API RP-579 and accommodates the potential effects of temper embrittlement and hydrogen assisted fracture. Temper embrittlement effects can be accounted for by use of typical fracture data for Cr-Mo steels of similar vintage as used in the construction of the reactor vessel in question or by using data from actual reactor heat samples exposed in the reactor over time. The potential for hydrogen assisted fracture can be evaluated for specific vessel situations by estimating residual hydrogen levels in the vessel steel after shutdown. At very low levels of hydrogen (2 ppm and lower) hydrogen assisted fracture should not be a concern. An envelope for the reactor operating temperature and hydrogen partial pressure conditions is defined below which hydrogen assisted cracking should not be a concern. It should be noted that a more detailed Level 3 assessment as defined in Part 3 of API RP-579 can be performed to further refine the assessment if more material toughness data, flaw size information and/or stress information is available on the vessel. This procedure has been used within our company to safely start-up and shutdown heavy wall Cr-Mo vessels.
Investigation on Tendency of Stress in Local Thin Area of Shell Plate of Oil Storage Tank
Authors: Yuan Hai , Kawano Kazuma , Sekine Kazuyoshi , Maruyama Hiroaki
Published: July 2008

The shell plate of oil storage tank is an important evaluating component in the Fitness-For Service Assessment (FFS), because it is required to have sufficient strength against static and dynamic pressures in both operating and earthquake conditions. This paper presents an investigation on the tendency of stress occurred in the local thin areas (LTAs) of shell plate subjected to an internal pressure by using a partial three-dimensional shell model. In the analyses, a LTA is assumed as a rectangular area or a ring area with a rectangular cross section, and its lengths in the longitudinal and circumferential directions are taken as study parameters. The tendency of stress ratio (the stress in LTA of shell plate to that without LTA) has been investigated and the analytical results show that there is a tendency for stress ratio to be going up when the longitudinal length of LTA lengthens gradually and the thickness of shell plate is decreased. But it is opposite for increasing the circumferential length, when the stress ratio is going down. The relation between the stress ratio and the shape of LTA with different combination of sizes are clarified by the analytical results.
Fitness for Service and Remaining Life Assessment for 1-1/4Cr-1/2Mo Reactor System Piping on a Catalytic Reformer Unit
Authors: Cheta Ayman M. , Konet Ray , Hoyt F. Skip
Published: July 2008

Fitness for service and remaining life assessment were performed on high temperature reactor piping to verify mechanical integrity for a desired remaining life. The NPS 20 1-1/4Cr-1/2Mo piping, which is the subject of this paper, was built in 1968 to the 1966 edition of ASA B31.3 for design conditions 465 psi at 950 °F / 365 psi at 1000 °F (3.16 MPa at 510 °C / 2.48 MPa at 538 °C) for hydrogen and naphtha service. The actual operating conditions are 400 psi at 900 °F / 330 psi at 950 °F (2.72 MPa at 482 °C / 2.24 MPa at 510 °C). Due to numerous reported failures in the industry in the 1980’s, the ASME codes for piping and pressure vessels lowered the allowable stresses for low alloy steels operating in the creep range, mainly above 900 °F (482 °C). Piping systems designed prior to changing the allowable stress do not satisfy today’s codes. The operating stresses which can lead to failure from potential damage mechanisms, e.g. creep, reheat cracking and general corrosion, are defined and their impact on fitness-for-service and remaining life evaluated. Acceptance criteria for different types of defects were established prior to the unit maintenance turnaround by: 1. Finite element modeling of assumed different degrees of weld peaking and pipe out-of-roundness for longitudinally welded pipe. 2. Piping flexibility / stress analysis to identify areas with the highest operating stresses. 3. Stresses from 1 and 2 above were used to calculate the creep life based on Larson-Miller parameter (API 530). Acceptable flaw sizes were limited by the desired remaining life. Inspection plans were developed to inspect for reheat cracking, creep damage, peaking, out of roundness, as well as general corrosion.
JSME Codes on Environmental Fatigue Evaluation
Authors: Nakamura Takao , Higuchi Makoto , Kusunoki Takehiro , Sugie Yasuaki
Published: July 2008

The “Guidelines for Evaluating Fatigue Initiation Life Reduction in the LWR Environment” (the MITI Guidelines) including equations to evaluate environmental fatigue were issued and notified the electric utilities in September 2000 by the former Agency for Natural Resources and Energy in Japan. The MITI Guidelines require the Japanese utilities to take into account environmental effects when conducting fatigue evaluation associated with Plant Life Management (PLM) activities for operating nuclear power plants. However, the MITI guidelines do not specify how to conduct the environmental fatigue evaluation under actual plant conditions. To provide a concrete and practical method to deal with environmental effects on fatigue evaluation of plant equipment, Thermal and Nuclear Power Engineering Society established the “Guidelines on Environmental Fatigue Evaluation for LWR Component” (the TENPES Guidelines) in 2002. Since then, the Japan Society of Mechanical Engineers (JSME) has reviewed the equations to calculate the environmental fatigue life correction factor, Fen in the MITI guidelines and the methods to evaluate the environmental fatigue in the TENPES guidelines considering the latest environmental fatigue data. Based on the result of the review, JSME intends to establish new environmental fatigue evaluation method. This paper explains the scheme and the technical basis of the evaluation methods in JSME codes, and the positioning of the codes to apply them to actual plant conditions. Another paper is released separately that shows the background of the equation to evaluate the fatigue life under the reactor cooling water environment.[19]
CFD-Tool for Assessment of the Reactor Pressure Vessel Integrity in Pressure Thermal Shock Conditions: Influence of Turbulence Model and Mesh Refinement on the Vessel Thermal Loading During PTS Transient
Authors: Martin A. , Benhamadouche S. , Bezdikian G. , Beaud F. , Lestang F.
Published: July 2008

Integrity evaluation methods for nuclear Reactor Pressure Vessels (RPVs) under Pressurised Thermal Shock (PTS) loading are applied by French Utility. They are based on the analysis of the behavior of relatively shallow cracks under loading PTS conditions due to the emergency cooling during SBLOCA (Small Break Loss of Coolant Accident) transients. This paper presents the Research and Development program started at E.D.F on the Computational Fluid Dynamic (CFD) determination of the cooling phenomena of a PWR vessel during a Pressurised Thermal Shock. The numerical results are obtained with the thermal-hydraulic tool Code_Saturne, in combination with the thermal-solid code SYRTHES to take into account the coupled effect of heat transfer between the fluid flow and the vessel. Based on the global and local Thermal-hydraulic analysis of a Small Break Loss of Coolant Accident transient, the paper presents mainly a parametric study which helps to understand the main phenomena that can lead to better estimating the margin factors. The geometry studied represents a third of a PWR pressure vessel and the configuration investigated is related to the injection of cold water in the vessel during a SBLOCA transient. Conservative initial and boundary conditions for the CFD calculation are derived from the global Thermal-hydraulic analysis. Both the fluid behavior and its impact on the solid part formed by cladding and base metal are considered. The main purpose of the numerical thermal-hydraulic studies is to accurately estimate the distribution of fluid temperature in the down comer and the heat transfer coefficients on the inner RPV surface for a fracture mechanics computation which will subsequently assess the associated RPV safety margin factors.
Drop Simulation of 6M Drum With Locking-Ring Closure and Liquid Contents
Authors: Wu Tsu-Te
Published: July 2008

This paper presents the dynamic simulation of the 6M drum with a locking-ring type closure subjected to a 4.9-foot drop. The drum is filled with water to 98 percent of overflow capacity. A three dimensional finite-element model consisting of metallic, liquid and rubber gasket components is used in the simulation. The water is represented by a hydrodynamic material model in which the material’s volume strength is determined by an equation of state. The explicit numerical method based on the theory of wave propagation is used to determine the combined structural response to the torque load for tightening the locking-ring closure and to the impact load due to the drop.
Dynamic Simulation of Shipping Package Subjected to Torque Load and Sequential Impacts
Authors: Wu Tsu-Te , Blanton Paul S. , Abramczyk Glenn A.
Published: July 2008

A numerical technique has been developed to simulate the structural responses of radioactive material packaging components requiring closure-tightening torque to the scenarios of the hypothetical accident conditions (HAC) defined in the Code of Federal Regulations Title 10 part 71 (10CFR 71). A rigorous solution to this type of problem poses a considerable mathematical challenge. Conventional methods for evaluating the residue stresses due to the torque load are either inaccurate or not applicable to dynamic analyses. In addition, the HAC events occur sequentially and the cumulative damage to the package needs to be evaluated. Commonly, individual HAC events are analyzed separately and the cumulative damage is not addressed. As a result, strict compliance of the package with the requirements specified in 10CFR 71 is usually demonstrated by physical testing. The proposed technique utilizes the combination of kinematic constraints, rigid-body motions and structural deformations to overcome some of the difficulties encountered in modeling the effect of cumulative damage in numerical solutions. The analyses demonstrating use of this technique were performed to determine the cumulative damage of torque preload, a 30-foot drop, a 30-foot dynamic crush and a 40-inch free fall onto a mild steel pipe.
Coordinated Research Projects at IAEA Concerning RPV and Structural Integrity
Authors: Server William , Hardin Timothy , Brumovsky´ Milan
Published: July 2008

The International Atomic Energy Agency (IAEA) has had a series of reactor pressure vessel (RPV) structural integrity programs that started back in the 1970s. These Coordinated Research Projects most recently have focused on use of the Master Curve fracture toughness testing approach for RPV and other ferritic steel components and on the issue of pressurized thermal shock (PTS) in operating pressurized water reactors. This paper will provide the current status for these projects and discuss the implications for improved safety of key ferritic steel components in nuclear power plants (NPPs).
Type B Package Radioactive Material Contents Compliance
Authors: Hensel S. J. , Watkins R. W. , Smith A. C.
Published: July 2008

Implementation of packaging and transportation requirements can be subdivided into three categories; contents compliance, packaging closure, and transportation or logistical compliance. This paper addresses the area of contents compliance within the context of regulations, DOE Orders, and appropriate standards. Common practices and current pitfalls are also discussed.
Don’t Miss “Obvious” Hazards: Lessons Learned From Chemical Safety Board Investigations
Authors: Wallace Stephen J.
Published: July 2008

The United States Chemical Safety & Hazard Investigation Board (CSB) was conceived by Congress following a series of catastrophic industrial accidents in the mid to late 1980s. This federal agency is charged with investigating incidents at chemical and manufacturing facilities, determining the causes, and making recommendations to prevent future accidents. This paper focuses on the findings from several CSB investigations related to equipment failure. Numerous codes, standards, and good practice guidelines are in place to govern the design, maintenance, and operation of vessels. However, the CSB has found that serious accidents continue to occur because of poor implementation of established guidance. This paper uses actual case studies to illustrate problems with equipment that ultimately led to catastrophes. Lessons learned from these incidents include designing equipment with adequate overpressure protection, adjusting inspection frequencies based on actual observations, and requiring written procedures for critical phases such as startup. Additional good practices and recommendations from the CSB are discussed with each of the case studies.
Comparative Corrosion Behavior of Two Palladium-Containing Titanium Alloys
Authors: Lian Tiangan , Yashiki Takashi , Nakayama Takenori , Nakanishi Tomoaki , Rebak Rau´l B.
Published: July 2008

The ASTM standard B 265 provides the requirements for the chemical composition of titanium (Ti) alloys. It is planned to use corrosion resistant and high strength titanium alloys to fabricate the drip shield at the proposed Yucca Mountain Repository. Titanium grade (Gr) 7 (R52400) and other Ti alloys are currently being characterized for this application. Ti Gr 7 contains 0.15% Palladium (Pd) to increase its corrosion performance. In this article we report results on the comparative short term corrosion behavior of Ti Gr 7 and a Ruthenium (Ru) containing alloy (Ti Gr 33). Ti Gr 33 also contains a small amount of Pd. Limited electrochemical testing such as polarization resistance and cyclic potentiodynamic curves showed that both alloys have a similar corrosion behavior in the tested environments.
Anodic Behavior of Alloy 22 in High Nitrate Brines at Temperatures Higher Than 100°C
Authors: Ilevbare Gabriel O. , Etien Robert A. , Estill John C. , Hust Gary A. , Yilmaz Ahmet , Stuart Marshall L. , Rebak Raul B.
Published: July 2008

Alloy 22 (N06022) may be susceptible to crevice corrosion in chloride solutions. Nitrate acts as an inhibitor to crevice corrosion. Several papers have been published regarding the effect of nitrate on the corrosion resistance of Alloy 22 at temperatures 100°C and lower. However, very little is known about the behavior of this alloy in highly concentrated brines at temperatures above 100°C. In the current work, electrochemical tests have been carried out to explore the anodic behavior of Alloy 22 in high chloride high nitrate electrolytes at temperatures as high as 160°C at ambient atmospheres. Even though Alloy 22 may adopt corrosion potentials in the order of +0.5 V (in the saturated silver chloride scale), it does not suffer crevice corrosion if there is high nitrate in the solution. That is, the inhibitive effect of nitrate on crevice corrosion is active for temperatures higher than 100°C.
Stress Analysis and Assessment for Nozzle Welding Area Enduring High Pressure and High Temperature
Authors: Zhang Wenge , Chen Xuedong , Yang Tiecheng , Li Jianrong , Yu Jilin
Published: July 2008

Hydrogenation reactor vessel as a key heat exchanging element equipment endures both high pressure and high temperature. Its nozzle welding areas have complicated stress states with both high stress level and high stress grads (as well as high strain grads). Defects and cracks are frequently found just on the welds or at heat-influence area by ultrasonic non-destructive inspection for this kind of in-service heat exchanger. To acquire the accurate stress states of nozzle welding area are fundamental necessary step on safety assessment and residual life predication for the components as well as the heat exchanger. A three dimensional finite element analysis model is performed using the on-site parameters measured directly from the in-service equipment. The temperatures and stress distribution at the nozzle welding areas of hydrogenation reactor vessel are obtained. By applying the CVDA-84 standard codes to the area which contains initial defects, critical crack size can be calculated and the safety assessment can be performance.
Experimental Investigation on Double-Layered Pipe During Hydro-Expanding
Authors: Zheng Jinyang , Liu Fujun , Ding Shoubao , Guo Xiaolian
Published: July 2008

Hydro-expanding is one of main methods in manufacturing double-layered pipes. Experimental investigation of the hydro-expanding pressure on double-layered pipe is presented in this paper. The hoop strains at the external surface of the outer pipe were measured in seven experiments. The special experiment phenomenon, the strain values being nearly constant for about fifteen minutes when first pressurizing to 23.6MPa, was observed. The relationship between the hydro-expanding pressure and the hoop stress at the external surface of outer pipe was obtained. The results indicate that the range of the hydro-expanding pressure and the residual contact pressure in the experiment are both in good agreement with those in theory with a maximum relative error of 5.46%, and provide references for engineering application and further research in determining the range of the hydro-expanding pressure.
A Discussion on the Performance of Continuum Plasticity Models for Fatigue Lifetime Assessment Based on the Local Strain Appraoch
Authors: De Jesus Abi´lio M. P. , Pereira He´lder F. S. G. , Ribeiro Alfredo S. , Fernandes Anto´nio A.
Published: July 2008

This paper presents a discussion on the performance of continuum plasticity models for fatigue lifetime assessment according to the local strain approach. Several cyclic plasticity phenomena such as the cyclic hardening/softening, ratchetting, cyclic mean stress relaxation and non-proportional cyclic hardening require, in general, specialized continuum plasticity models. Continuum plasticity models, available in commercial finite element codes (e.g. ANSYS®), with linear, multilinear and nonlinear kinematic hardening are identified using the experimental information available for a pressure vessel steel — the P355NL 1 steel. The potentialities of these plasticity models to describe the material cyclic behaviour are discussed, limiting the discussion to proportional loading. The plasticity models are applied to evaluate the strain ranges and mean stresses of a nozzle-to-plate connection. Two analysis strategies are applied to extract the strain ranges, namely the Twice Yield (TY) and the Cycle-by-Cycle (CBC) methods. The mean stress is only evaluated using the CBC method since the TY method has been proposed only for evaluation of the strain ranges. It is demonstrated that the TY and CBC methods gives similar results for the linear and multilinear kinematic hardening plasticity models. The plasticity model can have an important effect on the evaluation of the mean stresses and thus on predicted strain-life results, if mean stress effects are taken into account in the local strain approach. Finally, the calculated strain ranges and mean stresses are used in the evaluation of the fatigue life of the nozzle-to-plate connection using a local strain approach, and predictions are compared with available experimental results. The effect of the mean stress is important for long lives and is very dependent on the continuum plasticity model and on the number of cycles modelled in the CBC extraction method. Although differences are observed in the estimation of the strain ranges, using the several plasticity models, relatively small differences in fatigue life estimations were resulted.
Study of a Major Mechanism for Self-Loosening of Bolted Joints
Authors: Wang Ziqin , Jiang Yanyao
Published: July 2008

A recent three-dimensional (3-D) finite element (FE) investigation on self-loosening of bolted joints revealed that two major mechanisms were responsible for the second-stage (nut rotation) self-loosening of bolted joints. One of the mechanisms is the slip-stick contact of the thread surfaces under the combined contact pressure and reversed bending moment exerted from the reversed transverse loading. The current investigation is a detailed study of the slip-stick contact of the thread surfaces with models that mimic the bolt loading condition. The contact pressure and the reversed bending moment are obtained from an earlier simulation for an M12 bolt. The FE simulations indicate that, with the contact pressure on the thread surface of the bolt and nut, the alternating bending moment results in the gradual motion between the contact thread surfaces. A detailed look at the contact surfaces reveals that localized slip along the tangential direction occurs in part of the contact area and the accumulation of this local slip is responsible for the gradual relative motion between bolt and nut. The FE simulations also indicate that the amplitude of the bending moment greatly influences the relative displacement between the bolt and the nut. There exists a threshold below which local slip will not occur. Results from a two-dimensional (2-D) model are discussed and compared with those obtained from a 3-D model.
Nonlinear Static Analysis of Orthotropic Piezoelectric Shallow Cylindrical Shell on Elastic Foundation
Authors: Gupta K. M. , Kumar Sandeep
Published: July 2008

With growth and emergence in the field of adaptive materials, the need arises to study their applications in the field of structural, aerodynamic, aerospace and other fields. These materials can be used as sensors, transducers, and actuators. Although their basic constitutive relations are already developed, but there is still a great deal of scope left in the field of applications. With this aim, a nonlinear static analysis of orthotropic piezoelectric shallow cylindrical shell on Pasternak foundation is investigated in the present work. Basic formulation of the problem is based on strain energy concept, and the governing differential equations are obtained by using Euler’s variational principle. Galerkin error minimization technique has been used to solve the governing differential equations. The results are presented for simply supported immovable edge boundary condition. Influences of shell geometry, foundation parameter, and piezoelectric properties on load-deflection characteristics for different radius-to-thickness ratios are studied. Numerical results have been obtained for different values of geometrical parameters in terms of load, displacement, and electric potential. Geometrical parameters are represented through non-dimensional entities η = a2/Rh, λ = Ka4/D11, and μ = Ga2/D11. The results are compared with nonlinear static analysis of an orthotropic shallow cylindrical shell without piezoelectric layer on Pasternak foundation. It is observed that an increase in the value of piezoelectric constant decreases the deflection of the shallow cylindrical shell under the identical values.
Plastic Collapse Assessment Procedure for Vessel With Local Thin Area Simultaneously Subjected to Internal Pressure and External Bending Moment
Authors: Konosu Shinji , Mukaimachi Norihiko
Published: July 2008

Assessment of the local thin area should be undertaken for both tension and compression bending. In this paper, simplified reference stresses for a flaw in a cylinder are proposed. By using these results, a newly-developed p-M (internal pressure ratio and external bending moment ratio) diagram which can evaluate the plastic collapse condition for pressure equipment such as vessels, piping and storage tanks with a local thin area simultaneously subjected to internal pressure, p, and external bending moment, M, due to earthquake, etc. is proposed. The p-M line is verified by comparison with the FEA results and the numerous results of experiment for a cylinder with a volumetric flaw obtained through the reference literatures. It was clarified that the differences in plastic collapse limit between the p-M line and DNV guideline under both internal pressure and compression moment became evident where the outer diameter/wall thickness of a cylinder is large and the yield ratio of the material is small.
Failure Assessment Curves (FACs) in Japanese FFS Code, HPIS Z101 Level 2
Authors: Konosu Shinji
Published: July 2008

The High Pressure Institute of Japan has prescribed the Japanese FFS code, HPIS Z101 Level 1, which can evaluate a crack-like flaw without an extensive knowledge of fracture mechanics. Level 2 is currently being studied and will also be prescribed. In HPIS Z101 Level 2, a two-parameter method (FAD: Failure Assessment Diagram) will be adopted. This paper reveals that FACs dependent on the type of materials should be specified. Kr-Lr relations calculated from experimentally obtained Ramberg-Osgood constants of several steels are compared with the FACs of BS7910 Level 2A & API 579 Level 2, R6 Option 1 and ASME N494-3. It is found that the FAC of ferritic steel in ASME N494-3 is pertinent to carbon steels with a marked yield point plateau while the FAC of BS7910 Level 2A & API 579Level 2 is suitable for ferritic steels other than carbon steels such as 0.5Mo, 2.25Cr-1Mo and 2.25Cr-1Mo-0.25V steels. Further, cut-off values dependent on the strength of the material and the plasticity interaction factors for the FAC of carbon steels are proposed.