bluuebunny/crossref_metadata_2025_split huggingface dataset:
New French Nuclear Pressure Equipment Regulation in 2019 and Use of Codes
Authors: Malouines Philippe , Wasylyk Andrew , Duranton Pascal 
Published: November 2019

Abstract
Nuclear regulations aim to minimize industrial risk, and assure the safety of workers and the public. In order to effective, regulations will often impact industrial processes and sometimes, industry organisation. It is therefore logical that any change in the regulation and its philosophy will have a significant impact on the industry.
This paper will present the evolution of the French regulations over the past 15 years, starting with the Nuclear Regulations which orientates the nuclear technology, toward maximizing safety of workers and public. Utilities and vendors have to comply with these regulations, which may modify the design and manufacturing process, and sometimes, industry organization. Through the case of the updating of French Nuclear order for pressure Equipment on September 3rd, 2018 [1], it will be reminded how the first Order in 2005 has affected current projects, and how nuclear codes has taken in account these new requirements from 2005 to 2015 [3]. It will be explained convergence of AFCEN codes requirements with regulation, and latest updating of ESPN Order in 2015 [3] and 2018 [1]. New approaches with Essential Safety Requirements, specific of European Regulation Pressure Equipment Directive in Europe (2014/68/UE) [7], give objectives to achieve, like risk analysis, Particular Material Appraisal (PMA), technical qualification of Material, among other, and they will be described, when they are applied to nuclear Equipment. Guides and AFCEN Technical Publication (PTAN) will illustrate in detail how the RCC M issued in 2018 [5] has been improved. The communication will conclude with the analysis of the effect of the new French regulation on nuclear reactor’s projects outside France.
Comparison of Ellipsoidal and Equivalent Torispherical Heads Under Internal Pressure: Buckling, Plastic Collapse and Design Rules
Authors: Zheng Jinyang , Li Keming , Yu Yehong , Zhang Zekun , Peng Wenzhu , Gu Chaohua , Xu Ping 
Published: November 2019

Abstract
Ellipsoidal and torispherical heads, whose geometric shapes are close, are usually used as end closures of internally pressurized vessels. In pressure vessel codes, for example, ASME BPVC Section VIII, ellipsoidal heads are designed as torispherical heads using geometric equivalency approaches. However, the difference between ellipsoidal and equivalent torispherical heads has not been studied in detail. In this paper, we first investigate the shape deviation between the two types of heads. Then we compare the elastic-plastic behaviors between ellipsoidal and equivalent torispherical heads as well as their failure modes, i.e., buckling and plastic collapse. It is found that ellipsoidal heads have more buckling resistance than equivalent torispherical heads, indicating that the current design rules for buckling failure based on the geometric equivalency approaches result in uneconomical design. Nevertheless, the shape deviation has little effect on plastic collapse pressures of ellipsoidal and equivalent torispherical heads, showing that the geometric equivalency approaches are applicable for such heads that fail by plastic collapse (bursting). In addition, the experimental and numerical results show that such heads experience geometric strengthening. The FE method considering the effect of geometric strengthening provides a good prediction about plastic collapse (bursting) pressure. However, the current design equation for bursting does not consider the effect of geometric strengthening, also leading to uneconomical design.
Therefore, in order to avoid uneconomical design, we recommend that (1) with respect to the buckling of ellipsoidal heads, a new design equation be proposed rather than implementing the geometric equivalency approaches, and (2) the current design equation for bursting be deleted, and a new design equation, considering the effect of geometric strengthening, be proposed for the bursting of ellipsoidal and torispherical heads subjected to internal pressure.
Elastic-Plastic Buckling Analysis of Spherical Latticed Shell of Large Scale Molten Salt Storage Tank
Authors: Tang Hui , Shi Qianyu , Wang Zhijian , Li Qi 
Published: November 2019

Abstract
In recent years, with the rapid development of solar thermal power technology in China, the key equipment molten salt storage tank is widely used. Instability is the primary failure mode for these large thin-walled structures. Thus, stability design for the molten salt storage tanks is significant. In this paper, the elastic and elastic-plastic buckling analyses of a spherical latticed shell are carried out with whole process load-deformation method considering geometric and material non-linearity. The critical buckling loads of these two analysis types are obtained from the load-deformation curve. Comparison between spherical latticed shells with channel beam and I-section beam is presented. The modeling method of finite element model for buckling analysis of latticed shell is discussed. This may provide a reference to the stability design of large scale storage tank.
European Project ATLAS+: Small and Large Scale Ductile Tearing Experiments on Ferritic Steel WB36 to Study Transferability of Material Ductile Properties
Authors: Dahl Anna , Moinereau Dominique , Le Delliou Patrick , Vincent Willy 
Published: November 2019

Abstract
The 4-years European project ATLAS+ (Advanced Structural Integrity Assessment Tools for Safe long Term Operation) has been launched in June 2017. One of its objectives is to study the transferability of material ductile properties from small scale specimens to large scale components and validate some advanced tools for structural integrity assessment.
The study of properties transferability is based on a wide experimental programme which includes a full set of fracture experiments conducted on conventional fracture specimens and large scale components (mainly pipes).
Three materials are considered in the programme : a ferritic steel WB36 typical from secondary feed water line in German PWR reactors, an aged stainless steel austenitic weld representative of EPR design and a typical VVER austenitic dissimilar weld (DMW).
This paper describes the experimental work conducted on the ferritic steel WB 36 (15NiCuMoNb5) and summarizes the experimental results available after 2 years of work.
Numerous mechanical tests have been conducted on a wide panel of fracture mechanics specimens for a full characterization of the ferritic steel: Tensile properties, Hardness, Charpy Energy, pre-cracked Charpy PCC, Master curve on CT and SENT specimens, ductile tearing properties on CT and SENT specimens.
In parallel, it is planned to test three 4PB large scale tests on pipings (FP1, FP2 and FP3) at room temperature on the EDF test facility with 3 configurations (shape, size and location) of cracks: through wall crack (TWC), internal and external ½ elliptical cracks. Progress of these large scale experiments is described including first results.
Stress Corrosion Cracking in Low Temperature Carbon Steel
Authors: Al-Harthi Sultan G. , Mohammad Sameer Mohammad Obaid 
Published: November 2019

Abstract
Repeated weld joints leaks were observed in newly commissioned non insulated low temperature carbon steel anhydrous ammonia pipes after few months of operations. A detailed investigation was carried out to identify the root cause which found to be usage of high strength filler wire which leads to stress corrosion cracking (SCC) and weld joints failure. Also, An Online advance inspection via Phased Array Ultrasonic Test (PAUT) was conducted to assess the condition of weld joints in anhydrous ammonia pipe loops. Moreover, three different samples of leaked weld joints were submitted for metallurgical failure analysis laboratory. The paper explains the root cause of the damage, Online PAUT inspection and the challenges faced during development of the rectification procedure and implementation.
Proposal of Ductile Damage Model Based on Unit Cell Analysis for Prediction of Ductile Crack Growth Resistance of Cracked Component
Authors: Yamada Takehisa , Ohata Mitsuru 
Published: November 2019

Abstract
The aim of this study is to propose the damage model on the basis of the mechanism for ductile fracture related to void growth and applicable to ductile fracture assessment for steels. In order to determine damage evolution law, void growth behavior in the material was investigated by elasto-plastic finite element analyses using unit cell model with an initial void. From the results of the unit cell analyses, it was evident that a void in unit cell grew nonlinearly with increasing applied macroscopic strain. Moreover, the relationships between normalized void volume fraction and normalized strain by each critical value corresponding to crack initiation were independent of stress-strain relationship of material and stress triaxiality state. Based on this characteristic associated with void growth, damage evolution law representing nonlinear damage accumulation was derived. Then, using the damage evolution law, ductile damage model reflecting void growth behavior and ductility of material was proposed.
For validation and application of the proposed damage model, ductile crack growth tests using bend specimens with a machined notch or a fatigue pre-crack were conducted for low carbon steel. The proposed damage model was implemented in finite element analyses and ductile crack growth simulations were performed for each bending test. Then, it was shown that the proposed model could accurately predict ductile crack growth resistance from machined notch root and fatigue pre-crack tip (R-curves) and the validity and applicability of proposed damage model to cracked components could be confirmed.
Review of Pressure Vessel Code Rules on Cold Forming Limits and Heat Treatment Requirements
Authors: Xu Kang , Rana Mahendra D. , White James 
Published: November 2019

Abstract
In pressure vessel fabrication, cold formed carbon and alloy steels are required to have a subsequent heat treatment because of the loss of ductility and toughness from cold forming. The requirements for heat treatment are dependent on the materials, thickness, amount of cold forming and service condition. There are significant differences among the pressure vessel codes on the requirements for cold forming heat treatment. In this paper, the code requirements for cold forming heat treatment are reviewed for ASME Section VIII Divisions 1 and 2, EN 13445-4 and GB-150. The technical basis of forming strain calculations is discussed. Based on experimental data on the impact toughness as a function of forming strain, and fracture mechanics studies on cold formed components, improved guidelines are proposed on cold forming limits for heat treatment.
Technical Basis of a Code Case to Provide a Strain-Based Acceptance Limits for Service Level D Evaluation of Piping Systems Under Section III of ASME Boiler and Pressure Vessel Code
Authors: Wen Jie , Adams Timothy M. 
Published: November 2019

Abstract
Section III, non-mandatory Appendix F and mandatory Appendix XXVII provide the evaluation rules for Service Level D loads. Appendix F, article F-1341.2 permits plastic analysis, but provides only a stress-based acceptance criteria. Strain-based acceptance criteria for use in Appendix XXVII is under development. Strain-based acceptance criteria for Level D service limits for piping would be beneficial, especially, for regions where extremely high seismic events exist. A Code Case for strain-based acceptance criteria for level D service limits of piping is being developed in Section III of the ASME Boiler and Pressure Vessel Code. This paper presents the technical basis of the strain-based acceptance criteria Code Case. The authors reviewed extensive literatures which were published over last 50 years to build the foundation of the Code Case. A historical background of the seismic rules is given to explain why the load cycles are limited to 20 as in Section III, Division I, Subsection NB/NC/ND-3622.2 This paper also explains the consideration of reversing dynamic load and non-reversing dynamic load and how they are combined in the analysis. Comparison to current Appendix F (Appendix XXVII) acceptance criteria and some existing test results are provided to show the acceptability and conservatism of this Code Case.
Thermal Aging Assessment and Microstructural Investigations of Alloy 52 Dissimilar Metal Welds for Nuclear Components
Authors: Yescas Miguel , Joly Pierre , Roch François 
Published: November 2019

Abstract
Dissimilar Metal Welds (DMW) are commonly found between the ferritic low alloy steel heavy section components and the austenitic stainless steel piping sections in nuclear power plants. In the EPR™ design which is the latest FRAMATOME Pressurized water reactor (PWR) these DMW involve a narrow gap technology with no buttering, and only one bead per layer of a nickel base alloy weld filler metal (Alloy 52).
In order to assess the thermal aging performance of this relatively new narrow gap DMW design, a significant internal R&D program was launched some years ago. Several representative mock-ups were thoroughly characterized in the initial condition as well as in the thermal aged condition, up to 50,000 hours aging at 350°C. The characterisations were focused on the fusion line between the ferritic low alloy steel (LAS) and the nickel base alloy since a particular microstructure is present in this area, especially in the carbon depleted area of the Heat Affected Zone (HAZ) which is often regarded as the weak zone of the weld joint. Metallography, hardness, nanohardness, chemical analyses, and Atom Probe Tomography, as well as fracture toughness tests were carried out on different specimens in different thermal aging conditions. The results show that the fracture toughness behaviour in the ductile-brittle domain of the low alloy steel carbon depleted HAZ at the interface with the alloy 52 weld metal of the DMWs is excellent, even for a thermal ageing equivalent to 60 years at service temperature. This was found in spite of the carbon depleted zone of the HAZ, the variations of hardness, chemical composition, particularly the carbon gradients, and the thermal aging effect induced by phosphorous segregation at grain boundaries.
Design Equation for Minimum Required Thickness of a Cylindrical Shell Subject to Internal Pressure Based on Von Mises Criterion
Authors: Lu James , Millet Barry , Kirkpatrick Kenneth , Mosher Bryan 
Published: November 2019

Abstract
Design equation (4.3.1) for the minimum required thickness of a cylindrical shell subjected to internal pressure in Part 4 “design by rule (DBR)” of the ASME Boiler and Pressure Vessel Code, Section VIII, Division 2 [1] is based on the Tresca Yield Criterion, while design by analysis (DBA) in Part 5 of the Division 2 Code is based on the von Mises Yield Criterion. According to ASME PTB-1 “ASME Section VIII – Division 2 Criteria and Commentary”, the difference in results is about 15% due to use of the two different criteria. Although the von Mises Yield Criterion will result in a shell wall thickness less than that from Tresca Yield Criterion, Part 4 (DBR) of ASME Division 2 adopts the latter for a more convenient design equation. To use the von Mises Criterion in lieu of Tresca to reduce shell wall thickness, one has to follow DBA rules in Part 5 of Division 2, which typically requires detailed numeric analysis performed by experienced stress analysts.
This paper proposes a simple design equation for the minimum required thickness of a cylindrical shell subjected to internal pressure based on the von Mises Yield Criterion. The equation is suitable for both thin and thick cylindrical shells. Calculation results from the equation are validated by results from limit load analyses in accordance with Part 5 of ASME Division 2 Code.
The Effect of Pedicle Screw Thread Shape on the Stress Concentration Under Lateral Bending
Authors: Yang Yucheng , Ma Qin 
Published: November 2019

Abstract
Pedicle screws (PS) are frequently used in medical spinal column fixation. Despite 7 out of 100 pedicle screws fracture inside of the patients’ body and under the claim that lateral bending is the main failure mode, little research has addressed the stress characteristics and the fracture location of the PS under lateral bending. This study focuses on the effect of thread design on the magnitude and location of maximum stress concentration. Four types of thread shapes are considered including V-shape, square-shape, buttress, and reverse buttress. Three-dimensional (3D) finite element (FE) methods are used in this investigation. A load of 150 Newton is applied at the screw head to simulate lateral bending. The models are created in SolidWorks. The 3D FE analysis is performed using the standard coding of ANSYS Workbench 19.1. Based on this study, it is found that the high stress concentration is located at the cortical bone region rather than at the cancellous bone region. Although the general stress patterns are similar, the PS thread shape design and the thread fillet radius may significantly affect on the magnitude and location of maximum stress concentration.
Selection of the Test Specimens for Seismic Tests of Air-Operated Valve Actuators for Nuclear Power Plants
Authors: Kojima Nobuo , Tsutsumi Yoshitaka , Matsubara Yoshinao , Nishino Koji , Ito Yasuyuki , Kubota Ryo , Suzuki Shigeki 
Published: November 2019

Abstract
The soundness for the function of air-operated valves in nuclear power plants during earthquake has been investigated via seismic test results and so forth. Since the seismic response acceleration has increased more and more with a recent reassessment of design earthquake ground motions conducted according to the revised Japanese nuclear safety regulation, it is necessary to evaluate the soundness for the function of various valves subject to large acceleration beyond design basis. The air-operated valves currently installed in the nuclear power plants in Japan play the important roles in the sever accident events. In this study, we classified them based on the valve type, manufactures and the previous test results. Furthermore, we proposed the strategy for evaluating the seismic-proof and the seismic test condition for examining the soundness of the dynamic function. Here, the dynamic function is defined as the function required under and after earthquakes.
A Multi-Factor Comprehensive Evaluation Method for Pipeline Integrity
Authors: Yang Jing , Wang Xiaolin 
Published: November 2019

Abstract
Pipeline integrity management is widely used as an effective means for pipeline safety management, in which integrity evaluation is an important part. To some extent, pipeline integrity can be interpreted as the safety condition of the pipeline, while safety is an eternal topic for pipeline operators. In numerous recent studies, the evaluation of pipeline integrity generally focuses on the evaluation of remaining strength and/or residual life, which is based on the defect size such as corrosion, dents, etc., obtained during inspection. However, pipeline integrity is not only related to the pipe body, all factors that may threaten the operation safety of the pipe should be considered, including the pipe body, ancillary facilities, the pipe security system, and the surrounding environment, etc.. Although some comprehensive models have been established recently to assess pipeline condition, there still exist limitations for practical application, such as quantification of integrity and complexity of analysis. Therefore this paper presents the development of a comprehensive integrity evaluation method based on multi-factor analysis. The method is developed by an integrated application of fuzzy mathematics, grey correlation analysis theory, and the artificial neural network technique. After establishing integrity evaluating indexes, fuzzy analysis is used to quantify and classify pipeline integrity, and grey correlation analysis to screen key influence indicators. Then a comprehensive predictive evaluation model can be generated using large amount of relevant sample data based on the artificial neural network technique. In the end of the paper, a simple case is applied to validate feasibility of this comprehensive integrity evaluation method. The comprehensive evaluation method is expected to be applied to determine the condition of pipeline integrity, and to grade and rank the integrity condition of pipes, so as to assist and optimize pipeline maintenance decision for pipeline operators.
INCEFA-PLUS: Increasing Safety in NPPs by Covering Gaps in Environmental Fatigue Assessment
Authors: Mottershead Kevin , Bruchhausen Matthias , Cicero Sergio , Cuvilliez Sam 
Published: November 2019

Abstract
INCEFA-PLUS is a five year project supported by the European Commission HORIZON2020 programme. The project commenced in mid-2015. Sixteen organisations from across Europe have combined forces to deliver new experimental data which will support the development of improved guidelines for assessment of environmental fatigue damage to ensure safe operation of nuclear power plants. Within INCEFA-PLUS, the effects of mean strain and stress, hold time, strain amplitude and surface finish on fatigue endurance of austenitic stainless steels in light water reactor environments are being studied experimentally, these being issues of common interest to all participants. The data obtained is being collected and standardised in an online environmental fatigue database, implemented with the assistance of an INCEFA-PLUS led CEN workshop on this aspect. Towards the end of the project it is planned that INCEFA-PLUS will develop and disseminate methods for including the new data into assessment approaches for environmental fatigue degradation.
This paper provides an overall update on project developments since it was last presented at PVP2018 [1]. As well as being a standalone paper, this document will also serve as an introduction to a companion paper being submitted to cover data generated by the project in more detail [2]. In particular, this paper summarises:
• The results for Phases 1 & 2 testing.
• The plans for Phase 3 testing.
• A summary of emerging sensitivities to, and interdependencies between:
o Mean strain and stress, surface finish, strain amplitude and hold time.
o Environment.
o Material.
o Laboratory.
• The latest thinking on the direction of the project in its final year.
• The latest thoughts on how the project results will be used to advance development of improved assessment guidelines.
• A summary of dissemination achieved and planned.
• Ideas for work after the end of INCEFA-PLUS.