bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of JSME Seismic Code Case by Elastic-Plastic Response Analysis to Practical Piping System
Authors: Otani Akihito , Kai Satoru , Kaneko Naoaki , Watakabe Tomoyoshi , Ando Masanori , Tsukimori Kazuyuki 
Published: November 2018

A Code Case in the framework of JSME Nuclear Codes and Standards is being developed to incorporate a seismic design evaluation methodology for piping by means of advanced elastic-plastic response analysis methods and strain-based fatigue criteria. The Code Case as an alternative seismic design rule over the current rule will provide a more rational seismic design evaluation than the current criteria.
This paper demonstrates an application result of the JSME Seismic Code Case to an actual complex piping system. The secondary coolant piping system of Japanese Fast Breeder Reactor, Monju, was selected as a representative of the complex piping systems. The elastic-plastic time history analysis for the piping system was performed and the piping system has been evaluated according to the JSME Seismic Code Case. The evaluation by the Code Case provides a reasonable result in terms of the piping fatigue evaluation that governs seismic integrity of piping systems. Moreover, it is found that the supporting forces and the response accelerations of the piping system obtained by the elastic-plastic response analysis also become more rational results than those with the current elastic response analysis. The contradiction of two requirements in piping design, flexibility for thermal expansion and rigidity for seismic response, can be effectively relaxed by use of the Code Case being developed.
Optimization of Reactor’s Start-Up and Shutdown Procedures by Transient Thermo-Mechanical Finite Element Analysis
Authors: Lee Sang-Mo , Kwon Ohgeon , Garcia Vitor Lopes 
Published: November 2018

Efficient refinery start-up and shutdown durations are vital in establishing prolonged productivity in refineries operating hydrotreating reactors. The benefits of efficient start up and shutdown cycles are extensive, and include considerable operational and cost reduction. Reduced start-up and shutdown cycles, however, require increased heating and cooling rates, which cause higher temperature gradients throughout the reactor vessel, consequently leading to higher thermal stresses, which may affect damage mechanisms and limit reactor’s life. The equipment’s OEM has defined guidelines for the reactor heating and cooling during start-up and shutdown cycles and any attempt to reduce the start-up and shutdown duration is usually limited by these guidelines. It is therefore necessary to carry out an engineering assessment to determine the effect of changing the start-up and shutdown procedures beyond the OEM guidelines on reactor’s life.
Multiple thermo-mechanical Finite Element analyses for a series of different start-up/ shutdown procedures, including the current procedure, were carried out to determine the through-wall thermal gradient and stresses, and identify the most critical locations. In order to estimate convective heat transfer coefficients, Computational Fluid Dynamic (CFD) analysis was utilized to describe the complex fluid flow behavior of the feedstock in the presence of catalysts and internal geometry features. Low Cycle Fatigue (LCF) was adopted as a main damage mechanism to quantify the damage as a result of the changed operating conditions. It was determined that the LCF life calculated in the reactor vessel’s critical damage locations was found to be sufficiently long with respect to the frequency of start/shutdown cycles, even with operating conditions exceeding the OEM limit. Therefore, alternative guidelines were suggested to achieve the time reduction in startup/shutdown operation by increasing ramp rates without compromising structural integrity of the vessel.
Experimental Results and Numerical Analyses of Tests Conducted on Large Alloy 600 Centre Cracked Tensile Specimens
Authors: Le Delliou Patrick , Dahl Anna , Sonnefraud Christophe , Vincent Willy 
Published: November 2018

Some components of the main primary circuit of PWR nuclear power plants contain nickel-base alloy 600 parts (steam generator (SG) tubes, steam generator partition plates, lower internal radial supports). It is well known that this alloy is prone to stress corrosion cracking in the primary water environment. In 2002, surface cracks were discovered for the first time in SG partition plates of EDF 900 MWe NPP. The integrity of the SG containing these cracks must be demonstrated for all operating conditions, including accidental conditions. Due to the high tensile consolidation rate and the high fracture toughness of alloy 600, this was proved using limit load analysis. However, for a thorough demonstration, an experimental program was launched at EDF/R&D to better understand the behaviour of cracks in this high fracture toughness material. Centre Cracked Tensile (CCT) specimens were selected for this experimental program, being closer to the industrial case than conventional CT specimens.
Two tests have been conducted at room temperature on large CCT specimens containing a semi-elliptical crack. The paper presents the design of the CCT tests, the material characterisation, the main results of the tests and their numerical interpretation.
Study on the Predictive Evaluation Method of Nonlinear Sloshing Wave Height of Cylindrical Tanks: Part 2 — Proposal and Examination of Applicability of the Predictive Evaluation Method
Authors: Sago Hiromi , Morita Hideyuki , Takata Tomoshige , Madokoro Hideki , Murakami Hisatomo , Yokoi Shinobu , Yamamoto Tomohiko 
Published: November 2018

When cylindrical tanks installed on the ground, such as oil tanks and liquid storage tanks, receive strong seismic waves, including the long-period component, motion of the free liquid surface inside the tank called sloshing may occur. If high-amplitude sloshing occurs and the waves collide with the tank roof, it may lead to accidents such as damage to the tank roof or outflow of internal liquid. Therefore, it is important to predict the wave height of sloshing generated by an earthquake input.
Sloshing is vibration of the free liquid surface, and when the sloshing wave height is small, it can be approximated with a linear vibration model. In that case, the velocity-response-spectrum method using velocity potential can estimate the sloshing wave height under an earthquake input. However, when the sloshing wave height increases and the sloshing becomes nonlinear, it is necessary to evaluate the wave height using other methods such as numerical analysis.
Taking into consideration that design earthquake levels tend to increase and the use of seismic isolation mechanisms has continued to spread in recent years, the amplitude of the long-period components of an earthquake input which act on cylindrical tanks may also increase. Therefore, although the evaluation of nonlinear sloshing wave height is important, there are few examples which quantitatively evaluate the wave height of nonlinear sloshing.
The purpose of this study is to construct a simple evaluation technique of a nonlinear sloshing wave height of cylindrical tanks. In this study, the simple evaluation technique of the nonlinear sloshing wave height was proposed based on the study result shown by the 1st report (PVP2018-84416). Moreover, in order to verify the applicability of the proposed evaluation technique, the shaking table test and flow analysis which used the small cylindrical tank were carried out. As a result, the applicability of the proposed evaluation technique has been verified.
Development of New Design Fatigue Curves in Japan: Proposal of a New Fatigue Evaluation Method
Authors: Asada Seiji , Hirano Akihiko , Saito Toshiyuki , Takada Yasukazu , Kobayashi Hideo 
Published: November 2018

In order to develop new design fatigue curves for carbon steels & low-alloy steels and austenitic stainless steels and a new design fatigue evaluation method that are rational and have clear design basis, Design Fatigue Curve (DFC) Phase 1 subcommittee and Phase 2 subcommittee were established in the Atomic Energy Research Committee in the Japan Welding Engineering Society (JWES). The study on design fatigue curves was actively performed in the subcommittees.
In the subcommittees, domestic and foreign fatigue data of small test specimens in air were collected and a comprehensive fatigue database (≈6000 data) was constructed and the accurate best-fit curves of carbon steels & low-alloy steels and austenitic stainless steels were developed. Design factors were investigated. Also, a Japanese utility collaborative project performed large scale fatigue tests using austenitic stainless steel piping and low-alloy steel flat plates as well as fatigue tests using small specimens to obtain not only basic data but also fatigue data of mean stress effect, surface finish effect and size effect. Those test results were provided to the subcommittee and utilized the above studies.
Based on the above studies, a new fatigue evaluation method has been developed.
Fast Reactor Core Seismic Experiment and Analysis Under Strong Excitation
Authors: Yamamoto Tomohiko , Iwasaki Akihisa , Kawamura Kazuteru , Matsubara Shinichiro , Harada Hidenori 
Published: November 2018

In design of fast reactor (FR) core components, seismic response must be evaluated in order to ensure the structural integrity. Thus, a core seismic analysis method has been developed to evaluate 3D core vibration behavior considering fluid structure interaction and vertical displacement (upward).
Thirty seven 1/1.5 scale core element models which shape hexagonal-arrangement were used to validate the core element vibration analysis code in three dimensions (REVIAN-3D). Based on the test data, the newly incorporated analysis model has been verified to respond to strong excitation.
Fast Reactor Core Seismic Experiment of Full Scale Single Model of Control Rod
Authors: Iwasaki Akihisa , Matsubara Shinichiro , Kawamura Kazuteru , Harada Hidenori , Yamamoto Tomohiko 
Published: November 2018

The control rod guide tube self-stands on the core support plate. The control rod is inserted in the control rod guide tube, and the control rod hangs from the upper structure of the reactor. At scrum in case of an earthquake, the control rod is detached and it sits on the seating structure in the control rod guide tube. The control rod guide tube is raised more easily than the fuel assembly by the vertical differential pressure of the core during operation, because the control rod guide tube is lighter than the fuel assembly. Therefore, it is necessary to restrain the rising of the control rod guide tube. The sleeve dashpot structure, in which a sleeve is attached on the upper surface of the receptacle tube, is employed. Moreover, the control rod guide tube is equipped with the control rod dashpot in order to restrain the vertical movement of the control rod. In case of an earthquake, horizontal vibrational behavior also arises. The horizontal vibration generates friction force in the vertical direction and it restrains the rising. In this seismic evaluation of the control rod guide tube and the control rod, only the vertical motion is taken into consideration because it becomes conservative side against the rising displacement.
The seismic evaluation of the control rod guide tube is performed in operating condition (the coolant is flowing upward); that of the control rod assembly (the control rod guide tube and the control rod) is performed in shutdown condition (the coolant is not flowing).
Seismic experiments were performed using a full-scale model of the control rod guide tube and the control rod, vertical excitation and water instead of liquid sodium in the actual plant, to verify the analysis method and to demonstrate the rising restraining effect of the sleeve dashpot and the control rod dashpot. In this study, the rising behavior of the control rod guide tube and the control rod was investigated. The effect of restraining rising by the sleeve dashpot and by the control rod dashpot was confirmed.
Fast Reactor Core Seismic Analysis for Verification of Assessment Model of Control Rod
Authors: Iwasaki Akihisa , Matsubara Shinichiro , Kawamura Kazuteru , Harada Hidenori , Yamamoto Tomohiko 
Published: November 2018

The control rod guide tube self-stands on the core support plate. The control rod is inserted in the control rod guide tube, and the control rod hangs from the upper structure of the reactor. At scrum in case of an earthquake, the control rod is detached and it sits on the seating structure in the control rod guide tube (Fig.1). In a vertical earthquake, the control rod guide tube is raised from the core support plate, and the control rod is also raised from the control rod guide tube. Therefore, drawing out may arise. During the earthquake after scrum, the rising behavior is different from the other core elements because the control rod and the control rod guide tube rise interfering each other.
The control rod guide tube is raised more easily than the fuel assembly by the vertical differential pressure of the core during operation, because the control rod guide tube is lighter than the fuel assembly. Therefore, it is necessary to restrain the rising of the control rod guide tube. The sleeve dashpot structure, in which a sleeve is attached on the upper surface of the receptacle tube, is employed. Moreover, the control rod guide tube is equipped with the control rod dashpot in order to restrain the rising displacement of the control rod.
This paper summarizes the analysis method of the rising behavior of the single control rod guide tube and the rising behavior of the control rod and the control guide tube after the control rod is inserted.
A Study on the Magnetic Distribution of Nd-Fe-B Permanent Magnets in Pipeline in Line Inspection Tool
Authors: Song Pan , Tang Xiaoying , Wang ShaoJun , Ren Bin , Zuo Yantian , Wang Jielu 
Published: November 2018

The pressure pipeline in line inspection technology is the most effective nondestructive testing method to detect the quality of buried oil and gas pipelines at present. In line inspection tool usually uses magnetic flux leakage (MFL) technology to detect the change of leakage magnetic field to detect pipeline defects. Permanent magnets magnetize the wall of the pipeline as an excitation. During the detection process, the magnetic field performance of permanent magnets is required to be high. At the same time, the magnetic performance of the permanent magnet in the magnetic cleaning pipe also determine the cleaning effect inside the pipeline. In this paper, the magnetic distribution of permanent magnets is studied and the Nd-Fe-B permanent magnets with the best magnetic properties are taken as the objects. The finite element simulation is used to optimize the shape of the permanent magnets with better magnetic distribution, and the magnetic intensity factors of the preferred cylindrical permanent magnets are analyzed. In addition, three experiments of the influence of temperature, the influence of the ferromagnetic combination, and the influence of the environment medium are conducted.
As a result, the relationship between the magnetic intensity of the Nd-Fe-B permanent magnets and the factors is obtained. The conclusion is of great significance to the design and research of permanent magnetic circuit in line inspection magnetization device.
FEM Calculations of SIF and COA for Through Axial Cracks in Pipes in Geometrically Nonlinear Formulation
Authors: Oryniak Andrii , Orynyak Igor 
Published: November 2018

The determination of stress intensity factors (SIF) and crack opening area or displacements (COA or COD) is important constituent when performing the “leak before break” analysis of piping systems in NPPs. The tabulated parametrical results of their calculation are widely presented in modern scientific and normative literature. Nevertheless, there is one aspect of crack behavior, at least in thin walled pipes, which still had not obtained its due attention. We mean here the geometrically nonlinear effect, which can be the big enough to be accounted for in practical applications.
It is considered in geometrically linear analysis that only the inner pressure opens the crack, and COA and SIF are directly proportional to it. SIF is presented usually as solution for infinite plate multiplied by so-called bulging factor, BF, which depends on dimensionless crack length, i.e. ratio of crack length divided on square root of product of radius, R, and wall thickness, t.
Two loading factors in thin walled pipes can contribute to geometrically nonlinear behavior. The first one is axial stresses induced by value of axial force or bending moment. The second one – is the inner pressure itself.
The most attention in present paper is given to influence of the axial force. With this goal the numerical models were created for pipes with different ratios of R/t (20, 30, 40, 50) and different dimensionless crack length (2, 4, 6, 8). To exclude the nonlinearity due to circumferential stress the inner pressure is kept as a very small value and dimensionless SIF and COD values are calculated with respect to axial force.
To prove the correctness of choosing the finite element types, meshing, number of elements along the thickness, loading steps the auxiliary problem of nonlinear modeling of transverse beam loaded additionally by very big axial force is considered. The very good correspondence was attained.
For the pipe with axial crack the careful verification of numerical model was performed by comparison with linear results existing in literature.
The results obtained are presented as a percentage of difference between the linear and nonlinear results. They show that influence of geometrical nonlinearity is fairly essential to be accounted in practice and can reach for practically real cases almost 3–10%. The change of SIF in percentages due to geometrical nonlinearity for different axial stress levels and for different crack lengths can be fairly well presented as unique dependence from product of stresses, radius to thickness ratio, and square root of dimensionless crack length. The change COD in central point of crack is slightly bigger than for SIF and the same unique dependence can be formulated for COD with only exception for small cracks λ < 3.
Fitness-for-Service Assessment of an Injection Point in a Boiler Feed-Water Line Subjected to Corrosion
Authors: Kaida Takuyo , Sasaki Masahiro , Baldomir Gutierrez Luis Alejandro 
Published: November 2018

When inspecting a piping system, injection points should receive specific attention because they are sometimes subject to accelerated or localized corrosion. If metal loss is found at the location of such injection points during the inspection, a Fitness-For-Service (FFS) assessment can be used to evaluate whether the component can continue to operate safely without a plant shutdown. A more practical method for assessing the integrity is needed to provide specific procedures for the FFS assessment of a piping branch, e.g., an area-replacement rule.
This paper will present a practical example of an FFS assessment of an injection point in a boiler feed-water line in which internal corrosion was found using ultrasonic testing. We outline a way to characterize the metal-loss shape and assess the integrity of the injection point. We also present a quill-type injection design as a permanent countermeasure.
High-Frequency Responses in Relation to the Use of Explicit Time Integration Method
Authors: Bae Sungjin 
Published: November 2018

Design of an Independent Spent Fuel Storage Installation (ISFSI) pad requires examining seismic stability and determining the static and dynamic loads of casks in accordance with the provision of 10 CFR 72.212 (Ref. 1). Since spent fuel storage casks are free standing structures on a concrete pad, cask rocking and sliding are expected to occur during an earthquake. NUREG/CR-6865 (Ref. 2) requires that the dynamic analyses consider the effect of soil-and-structure interactions between supporting soil and concrete pad as well as between casks and concrete pad. When casks exhibit rocking or sliding, nonlinear analyses are performed to handle the contact, and explicit time integration analyses with very short period of time step are often used to analyze the dynamic contact behavior of casks.
Explicit time integration analyses are more prone to contain high-frequency response than implicit time stepping analyses because of the use of very small time step and the limitation of damping model. A cask analysis case is presented in this paper to illustrate high frequency responses associated with the use of Rayleigh mass proportional damping, which is a commonly used damping model for explicit time integration analyses. A modified mass proportional damping expression is proposed to improve the responses of soil and casks.
Global Matrix 3.0 Physical Activity Report Card Grades for Children and Youth: Results and Analysis From 49 Countries
Authors: Aubert Salomé , Barnes Joel D. , Abdeta Chalchisa , Abi Nader Patrick , Adeniyi Ade F. , Aguilar-Farias Nicolas , Andrade Tenesaca Dolores S. , Bhawra Jasmin , Brazo-Sayavera Javier , Cardon Greet , Chang Chen-Kang , Delisle Nyström Christine , Demetriou Yolanda , Draper Catherine E. , Edwards Lowri , Emeljanovas Arunas , Gába Aleš , Galaviz Karla I. , González Silvia A. , Herrera-Cuenca Marianella , Huang Wendy Y. , Ibrahim Izzeldin A.E. , Jürimäe Jaak , Kämppi Katariina , Katapally Tarun R. , Katewongsa Piyawat , Katzmarzyk Peter T. , Khan Asaduzzaman , Korcz Agata , Kim Yeon Soo , Lambert Estelle , Lee Eun-Young , Löf Marie , Loney Tom , López-Taylor Juan , Liu Yang , Makaza Daga , Manyanga Taru , Mileva Bilyana , Morrison Shawnda A. , Mota Jorge , Nyawornota Vida K. , Ocansey Reginald , Reilly John J. , Roman-Viñas Blanca , Silva Diego Augusto Santos , Saonuam Pairoj , Scriven John , Seghers Jan , Schranz Natasha , Skovgaard Thomas , Smith Melody , Standage Martyn , Starc Gregor , Stratton Gareth , Subedi Narayan , Takken Tim , Tammelin Tuija , Tanaka Chiaki , Thivel David , Tladi Dawn , Tyler Richard , Uddin Riaz , Williams Alun , Wong Stephen H.S. , Wu Ching-Lin , Zembura Paweł , Tremblay Mark S. 
Published: November 2018

Background: Accumulating sufficient moderate to vigorous physical activity is recognized as a key determinant of physical, physiological, developmental, mental, cognitive, and social health among children and youth (aged 5–17 y). The Global Matrix 3.0 of Report Card grades on physical activity was developed to achieve a better understanding of the global variation in child and youth physical activity and associated supports. Methods: Work groups from 49 countries followed harmonized procedures to develop their Report Cards by grading 10 common indicators using the best available data. The participating countries were divided into 3 categories using the United Nations’ human development index (HDI) classification (low or medium, high, and very high HDI). Results: A total of 490 grades, including 369 letter grades and 121 incomplete grades, were assigned by the 49 work groups. Overall, an average grade of “C-,” “D+,” and “C-” was obtained for the low and medium HDI countries, high HDI countries, and very high HDI countries, respectively. Conclusions: The present study provides rich new evidence showing that the situation regarding the physical activity of children and youth is a concern worldwide. Strategic public investments to implement effective interventions to increase physical activity opportunities are needed.