bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Friction on Structural Capacities of a Subsea Intervention System Equipment
Authors: Sepehri Ali , Bansal Gaurav 
Published: November 2023

Abstract
The offshore oil and gas industry is drilling into and producing from wells in high-pressure, high-temperature (HPHT) environments. This has created a greater demand to develop more advanced tools and new technology to safely overcome the challenges in these operations. Due to the sensitivity and potential impact on the environment, the industry is striving to homogenize the design and acceptance criteria. The API 17G is the industry standard for offshore intervention operations. This standard adopts the methodologies from ASME Boiler Pressure Vessel Code (BPVC) Section VIII, Div. 3.
The objective of this study is to evaluate structural capacity of a subsea intervention system equipment according to API 17G standard by utilizing Yielding Load Method for single and combined loads per elastic-plastic analysis with no strain hardening. The assembly has multiple tightly fitted parts that can slip and slide upon application of external loads. Large deformations (nonlinear geometry) shall be included when analyzing such models. Contacts are modeled with friction. Therefore, application of real friction value is important for accuracy of results that are representative of realistic operations. A sensitivity study is conducted to assess the effect of friction on the structural capacity. In addition, absence of through section yielding criterion is also verified.
History and Technical Scope of Code Case N-513
Authors: Parker Stephen M. , McCracken Stephen L. , McGill Robert O. , Patten Ioannis D. 
Published: November 2023

Abstract
ASME Section XI Case N-513-6, Evaluation Criteria for Temporary Acceptance of Flaws in Moderate Energy Class 2 or 3 Piping and Gate Values [1], is one of the most widely implemented code cases within the U.S. nuclear industry. The primary purpose of the Code Case is to provide evaluation criteria for flaws within moderate energy, safety-related piping to allow for continued plant operation without repair/replacement until the next scheduled refueling outage. Utilities may avoid an unscheduled plant shutdown provided structural integrity is demonstrated and other requirements are met. Periodic examinations of the flaw during the temporary acceptance period are required by N-513 to ensure the flaw has not grown beyond the acceptable flaw size. N-513 is typically implemented to disposition flaws found in service water piping made of carbon steel that is exposed to raw water where active corrosion mechanisms exist. The Code Case can also be applied to stainless steel and nonferrous material components.
The purpose of this paper is to provide a history of N-513, its technical scope, current ASME Code and U.S. regulatory status, as well as proposed changes for an upcoming revision. This paper also provides a secondary benefit of consolidating the history and development of this important nuclear industry flaw evaluation methodology for traceability and knowledge transfer purposes.
Operational Experience With Application of Appendix G Methods for Irradiated Pressure Vessels
Authors: Edge Nathan , Cairns Scott , Dutton Oliver 
Published: November 2023

Abstract
ASME III Appendix G provides a non-mandatory approach for obtaining the allowable loadings for ferritic pressure-retaining components based on the principles of Linear Elastic Fracture Mechanics (LEFM). Its purpose is to derive a relationship between Temperature and allowable Pressure of a ferritic vessel in order to prevent it from being subjected to high pressure (and therefore stress) when the metal temperature is low and potentially susceptible to non-ductile failure. The purpose of this paper is to present operational experience using ASME III Appendix G to form operational boundaries for specific irradiated pressure vessels. An overview of the historic and recent use of ASME III Appendix G is presented alongside observations on improvements and relaxations of conservatisms inherent to this method. A discussion is also presented regarding alternative methods which link the calculation of maximum allowable pressure during low temperature operation to the defect tolerance assessments produced in support of safety cases, whilst maintaining appropriate levels of conservatism in the assessment. The conclusion of the paper is that whilst ASME III Appendix G generally supports the provision of reasonable operational boundaries for irradiated ferritic pressure vessels there are a number of alterations and revisions required for specific components, and indeed specific regions of components, where standard methods result in pessimistic limitations to performance.
Research on Flow Induced Vibration Tandem Towers Under Passive Control
Authors: Wang Jiawei , Tang Bowen , Tan Wei 
Published: November 2023

Abstract
The flow-induced vibration (FIV) of the tower is one of the important reasons for tower failure. It is very important to take effective manual measures to control FIV for the safety and operation of the tower. Helical strakes can effectively interfere with the Karman vortex street and suppress vortex-induced vibration of isolated structures. Due to the vortex structure interaction, the mechanism of FIV control of helical strakes on tandem cylinders remains to be studied. The idealized model of a multi cylinder system with elastic support has been recognized in many fields, such as aviation engineering, nuclear engineering, ocean engineering, and wind engineering. Therefore, in this paper, the tandem cylinders wind tunnel experiment is designed, and a helical strakes installed on the wall of the cylinder model of the tower is designed. The structural dimensions and shapes are mainly involute, square, and D-shape. The vibration respond of the cylinder model at different distances are explored, and the effects of different sections, screw pitches, and helical strakes fin heights on the crosswind vibration response of the cylinder model are investigated. Compared with a series of smooth cylinders, the vibration amplitude of the cylinder with a D-shape helical strakes is reduced by 89%. Furthermore, based on a D-shaped section, the influence of two parameters of helical strakes h (fin height) and P (pitch) on the amplitude response of tandem cylinders is explored, and the parameters of optimal D-shaped helical strakes under different spatial arrangements are given. The research results can be used for the vibration reduction research of tandem towers.
Response of Buried Pipelines Under Permanent Ground Movements: Physics-Informed Deep Neural Network Approach
Authors: Taraghi Pouya , Li Yong , Yoosef-Ghodsi Nader , Fowler Matt , Kainat Muntaseer , Adeeb Samer 
Published: November 2023

Abstract
Long-distance underground pipelines are inexorably constructed over harsh geological fields exposing them to geohazards resulting in both transient and permanent ground movement. The permanent ground movements caused by landslides, liquefaction, ground subsidence, slope failures, fault movement, etc., can result in large deformation threatening the safety and integrity of the pipelines. Therefore, evaluation of the structural response, i.e., displacement and strain fields of the buried pipelines exposed to the permanent ground displacement is a major concern for the industry. The mechanical and physical behavior of the pipelines subjected to ground movement can be described mathematically using nonlinear Partial Differential Equations (PDEs) by adopting the Euler-Bernoulli beam theory with large deformation. The model takes into account the nonlinearities caused by the pipe-soil interaction and pipe geometry. Various methods, including the Finite Element Method (FEM) and Finite Difference Method (FDM), can be used to solve the nonlinear PDEs and thus predict the structural response. However, the FEM usually requires complicated simulation using costly commercial software. Also, both the FE and FD methods are mesh-dependent. On this basis, this research endeavor proposes and utilizes an inexpensive, novel, easy-to-implemented, simulation-free, and meshless method to get the response. As a result, Physics-Informed Neural Networks (PINNs), deep-learning neural networks that consider the underlying law of physics in PDEs, can be a potential strategy to deal with PDEs with high complexity. To this end, the neural networks thoroughly learn based on the incorporated physical laws together with the boundary and/or initial conditions, eliminating the need for large training datasets. The obtained structural response, applicability, and accuracy of the predicted results of the proposed method are assessed by comparison with the obtained results from FEM.
Potential of Variational Auto-Encoder as an Alternative to a Welding Residual Stress Profile Sampling Model
Authors: Oh Changsik , Kim Jin-Gyum , Kang Sung-Sik , Lee Sangmin 
Published: November 2023

Abstract
Primary Water Stress Corrosion Cracking (PWSCC) is a significant degradation mechanism for probabilistic Leak-Before-Break evaluation. Welding residual stress profiles, which have a great influence on the evaluation results, are difficult to measure and have a large uncertainty due to very limited data. Therefore, constructing welding residual stress profiles by reflecting the actual characteristics is an important part in the probabilistic evaluation.
This paper analyzed whether a generation model based on artificial neural networks could be an alternative to a sampling model of welding residual stress profiles. The network selected in this study is the Variational Auto-Encoder (VAE), which is well-known for learning the distribution of training data. Like the Auto-Encoder, the VAE is based on deep neural networks composed of an encoder and a decoder, but additionally learns the probability distribution of the input data. Systematically constructed sinusoidal wave training data sets were used to investigate the characteristics of the VAE. Amplitude and phase changes were made to generate the training data sets showing the self-balancing nature of the welding residual stress profile. The results showed that the generated data well represented the features of the training data, and demonstrated its potential as an alternative to a welding residual stress profile sampling model.
INCEFA-SCALE Project – Phases 1 and 2 of Testing Programme
Authors: Beswick Jack , Doremus Luc , Martin Oliver , Le Roux Jean-Christophe 
Published: November 2023

Abstract
INCEFA-SCALE is a five-year project supported by the European Commission HORIZON 2020 programme. It is the successor to the INCEFA-PLUS programme that ran from 2015 to 2020. INCEFA-SCALE kicked off in September 2020. The objective is to advance the ability to predict lifetimes of Nuclear Plant components when subjected to Environmental Assisted Fatigue (EAF) loading.
It has been generally observed by nuclear plant operators that there appears to be a disconnect between the perceived difficulty of providing an acceptable assessment result with the current EAF methodologies and the good service experience with regard to this specific degradation mechanism. It is internationally recognised that a possible contributor to this discrepancy is the transferability of laboratory-scale tests to real nuclear components. This is the key knowledge gap addressed by INCEFA-SCALE. To address this gap, the project has identified specific loading, geometric and environmental conditions which are not fully understood and may be considered excessively pessimistically in assessment. The conditions include variable amplitude and multiaxial loading, stress raising features such as notches, and the transferability of results between air and PWR environments, and between specimens with differing surface finishes, under the complex loading scenarios under consideration. Test matrices have been designed to deepen the understanding of specific materials’ (stainless steels) fatigue performance under these conditions, and the testing is well underway at the time of writing.
This paper will give an overview of the INCEFA-SCALE testing carried out to date, from the first two one-year phases of the testing programme. The testing and associated analysis has been designed to better understand the material behaviour at the component scale, and assess the applicability of models, developed elsewhere in the project, to predict the lives of these components, which are in turn informed by comprehensive characterisation of the material after failure. The test results are presented in a manner to allow comparison between the experimental fatigue lives and those predicted with standardised assessment procedures, such as NUREG/CR-6909, with comment on how more advanced models (addressed in a different paper), could be used to improve predictions.
Repeatability and Uncertainty Study of Strain Measured on Coupled Fluid-Structure Vessels in Response to High Intensity Proton Pulses
Authors: Jiang Hao , Winder Drew , Liu Yun 
Published: November 2023

Abstract
Spallation Neutron Source (SNS) produces neutrons through spallation reactions with the short pulse (∼0.7 μs) operated at a repetition rate of 60 Hz with 1.0 GeV protons onto the mercury target in a stainless-steel vessel. Each pulse causes a distributed pressure field in the mercury, with pressures exceeding 20 MPa. Dynamic high-pressure waves created by the proton pulses interact with the stainless-steel vessel. Fluid-structure interaction causes stress cycles in the target vessel and leads to fatigue cracks and cavitation of the mercury, which leads to further damage. Strain measurements are critical for understanding and improving the lifetime of the target vessels. The measurements also allow evaluation of the efficacy of pulse mitigation techniques such as injecting small helium gas bubbles into the flowing mercury.
Since 2015, researchers at SNS have used fiber-optic sensor systems to measure dynamic strain responses of the target vessels. An abundance of mercury target strain data has been collected. We would like to use these strain data to validate simulation results. It is important that the uncertainty of the measurements is quantified as part of the validation process. This paper focuses on the repeatability and uncertainty study in strain measurement data of SNS target vessels. The potential reasons causing the variance associated with measurements are investigated and discussed.
An Approach to Include the Effects of Plasticity in the Calculation of Crack Opening Areas for Through-Wall Cracks Subject to Combined Primary and Secondary Loading
Authors: James Peter , Brayshaw William , Sharples John 
Published: November 2023

Abstract
The work presented within this paper looks at estimates of crack opening area (COA) under elastic-plastic material conditions.
Developing leak before break (LbB) arguments with secondary (thermal or weld) stresses present is challenging. This potentially results from defect assessment methods like R6 not including guidance on the effect of plasticity on COA estimations in the presence of the secondary stresses, where the COA would be expected to increase compared to the elastic COA. The corresponding elastic-plastic stress intensity factor (KJ) could, conversely, reduce compared to handbook elastic solutions for stress intensity factor (KI).
Current practise within an LbB assessment in the UK would be to assume a plasticity correction is applied to KI, calculated using the R6 failure assessment diagram (FAD) as a J estimation scheme, to provide KJ. COA’s are evaluated elastically to ensure that the assessment under-estimates real-plant scenarios and is therefore generally conservative. Including plasticity in COA evaluations will allow assessment of COA to be more accurate, and therefore provide a reduction in conservatism compared to current guidance when a defect is in the presence of a single load type or when different loading types are combined.
This paper presents an approach which allows plasticity to be included in COA evaluations by calculating an additional crack opening as a result of plasticity, based on crack tip opening displacement and an enhancement calculated from the contributions of elastic and plastic reference strain (and is therefore consistent with the reference stress methods contained in R6 and elsewhere). This resulting crack opening area is then added to the elastic COA (COAe) calculated from the solutions published in a previous ASME PVP paper by France et al. The results of this approach are compared to elastic-plastic FEA results, where the primary membrane and secondary through-wall bending stresses were investigated when in isolation and combined with respect to K and COA.
The method outlined herein provides an increase in crack opening and therefore a reduction in conservatism compared to the FEA results, whilst remaining conservative; i.e. elastic-plastic COA prediction (COAep) is less than the FEA results.
Where a secondary through-wall bend has been applied in isolation, the restriction of crack overclosure (inclusion of crack face contact) in the FEA generates greater opening at the tensile surface. This is not replicated in the COAep method developed in this work and would need further development.
Under combined loading, the inclusion of plasticity in COAep has a small effect as the primary and secondary stresses are low and the secondary stresses relax due to plasticity, ensuring the response remains nominally elastic and is therefore consistent with existing methodology.
Graphite Material Model Calibration for Conceptual Design and Core Configuration Studies
Authors: Young Amanda , Horne Graeme , Gray Richard , Kent Daniel , Joyce Mark 
Published: November 2023

Abstract
Nuclear graphite is a candidate moderator material for many high temperature advanced reactor concepts. However, the material properties of graphite used in this application evolve during service, principally as a function of fast neutron dose, irradiation temperature and, if relevant, radiolytic oxidation. In these applications, the graphite moderator components also define the core geometry, including channels for coolant and reactivity control devices. One of the most significant threats to the core structure continuing to meet its design requirements is graphite dimensional change, which can cause significant deformation in the components through life.
This paper proposes an approach to this problem by defining a semi-empirical model for the behaviour of graphite in a nuclear environment which can be calibrated to experimental data. It can then be used by Finite Element (FE) software to provide a prediction of expected behaviour of core components. Whilst this approach is used to support continued operation of the UK fleet of Advanced Gas-cooled Reactors (AGRs), it is also judged appropriate to inform the pre-conceptual design stage of new reactor core designs. Being able to rapidly assess different core configuration options and their compliance with the guidance in ASME Section III Division 5 is a valuable tool in the early stages of design, particularly when irradiated material data is sparse.
Once a best estimate prediction has been made a robust approach to sensitivity studies is required, aimed at ensuring that a particular core design is tolerant to material evolution uncertainty. This should enable design work to proceed in parallel to the collection of detailed material evolution information significantly reducing risk and the time to complete the system design and assurance process.
Re-Evaluating the Minimum Required Distance Between a Local Thin Area in a Cylinder and an Ellipsoidal Head
Authors: Bouse Scott D. , Hill Lance , Altstadt Steven , Sarzynski Melanie 
Published: November 2023

Abstract
Many of the assessment procedures in API 579 / ASME FFS-1 require that flaws to be assessed must be located a minimum distance away from a Major Structural Discontinuity to ensure that the disruptions caused by the discontinuity do not adversely affect the conservatism of the calculations. Flaws in a cylinder with a Distance to Major Structural Discontinuity (Lmsd) less than 1.8*sqrt(Dt) are typically excluded from basic assessments, regardless of the type of discontinuity (or flaw) in question. This work explores the impact of a Local Thin Area (LTA) in a cylindrical shell as the discontinuity approaches a 2:1 ellipsoidal head. In this paper, the authors populated an Elastic-Plastic parametric study spanning a wide range of cylindrical thickness-to-diameter ratios (D/t), flaw sizes (both longitudinal and circumferential), materials, flaw severities, and proximity to both 2:1 ellipsoidal heads and hemispherical heads in order to characterize the responses. The results imply the existence of several classes of structural discontinuity, along with conditions under which some discontinuities might either act to support or de-stabilize a cylindrical shell against plastic collapse. The authors demonstrate that under supportive conditions, an LTA in a cylinder can approach certain discontinuities with negligible effects. In some cases, the limiting load reliably increases due to the interaction with the discontinuity. The work concludes with broader observations on discontinuity types and the circumstances under which those discontinuities might be found to be beneficial.
Oxidation Properties of Graphitic Packings Used in Low Emission Valves
Authors: Girão Carlos D. , Ruffin Mark , Pontes João H. 
Published: November 2023

Abstract
Flexible Graphite is used in a variety of seals because of its good thermal resistance, chemical stability and high conformability. It is widely used throughout the industry, and it is present in most low emission packing solutions associated to some content of PTFE. However, graphite will show appreciable oxidation when exposed to air at elevated temperatures and PTFE is subject to thermal degradation thus leading to mass loss and consequently reducing sealing performance. With the growing need to evaluate Fugitive Emission at higher temperatures, API 622 has introduced in March of 2022 a High Temperature Testing Procedure to access seal performance at 400°C, and modified its Packing Ring Weight Loss Test procedure to include a 24h hold at 593°C to measure seal mass loss. The scope of this paper is to evaluate the effect of temperature on low emissions packings composed of graphite and PTFE. The influence of test method in the oxidation rate of inhibited graphite from different sources, using thermogravimetric analysis and a muffle oven are investigated at temperatures ranging from 400°C to 700°C. A comparison is presented among different forms of graphite — tape, yarn and packing. Additional comparative weight loss data are reported among packings with PTFE, without PTFE, tested exposed to air, and confined in a test rig simulating a stuffing box.