bluuebunny/crossref_metadata_2025_split huggingface dataset:
International Civil Ageing Management and Assessment Methodology of Concrete
Authors: de Haan – de Wilde F. H. E. , de Bont C. G. M. 
Published: November 2019

Abstract
For many nuclear power plants worldwide the operation period will be extended to 60 or 80 years in the coming years. As the operation period increases, the importance of knowledge of ageing mechanisms increases. In the framework of LTO there is limited knowledge about ageing and structural integrity of concrete structures.
Knowledge about the strength of concrete structures and modelling thereof can be improved for a more complete knowledge base on ageing and degradation mechanism in nuclear facilities. Therefore, effort is required to improve the knowledge of concrete, material models and finite element modelling techniques as well as the assessment method.
Recent developments have shown that ageing of civil structures receive more attention internationally (E.g. concrete degradation in bunker building Doel). Traditionally a large part of the research and development is focused on mechanical issues like piping and vessels. In order to increase the knowledge in the field of civil structures, the focus is on investigation of ageing of concrete and determining analysis methods.
This paper focuses on the development of a practical assessment method for ageing of civil structures.
As a first step information from international publications and other sources on civil structures ageing issues and management thereof, will be gathered. Well known international standards taking care of ageing phenomena based on problem areas and good practices are IGALL and GALL.
IGALL and GALL contain information tables based on international experience. This is the starting point of the research in finding an assessment methodology for civil ageing management. It will be shown that IGALL and GALL contain very similar elements. Sorting on the AMPs results in a practical set of datasheets with summarizing information per AMP, including the underlying international experience. The datasheets are of limited size, presenting an helpful overview of the relevant structures or components, materials, environment and mechanisms.
A method for civil ageing management is proposed which will be applied and developed in more detail in future research. Further research is necessary to develop a specific assessment methodology for concrete.
Continued Safe Operation (LTO Research Reactors) High Flux Reactor, Petten
Authors: Stefanini L. , de Haan – de Wilde F. H. E. , Offerein J. F. 
Published: November 2019

Abstract
The HFR is one of the most powerful and versatile Research Reactors in the world. Because of its strategical importance in the medical isotopes production, after 57 years of operating experience a Continued Safe Operations (CSO) mission will take place. The CSO project structure is based on the outline given in the IAEA draft Safety Guide SSG-48. The ageing management for the HFR is evaluated based on the IAEA Specific Safety Guide SSG-10. Moreover, the approach to the contents of the project is supported by the IAEA Draft Guidelines for Peer Review of “Ageing Management of Research Reactors for Continued Safe Operations”. The HFR is the second Research Reactor (RR) in the world to undergo this type of assessment and its experience will be extremely valuable in setting the international standards for CSO of research reactors. This paper describes the phases of the CSO project, the challenges encountered and the experience built during its development.
An Update on the Investigation of Fracture Toughness Properties of the High Flux Reactor Vessel From Surveillance Test Campaign in 2017
Authors: Kolluri M. , de Haan – de Wilde F. H. E. , Nolles H. S. , de Jong A. J. M. 
Published: November 2019

Abstract
The reactor vessel of the High Flux Reactor (HFR) in Petten has been fabricated from Al 5154-O alloy grade with a maximum Mg content of 3.5 wt. %. The vessel experiences large amount of neutron fluences (notably at hot spot), of the order of 1027 n/m2, during its operational life. Substantial damage to the material’s microstructure and mechanical properties can occur at these high fluence conditions. To this end, a dedicated surveillance program: SURP (SURveillance Program) is executed to understand, predict and measure the influence of neutron radiation damage on the mechanical properties of the vessel material. In the SURP program, test specimens fabricated from representative HFR vessel material are continuously irradiated in two specially designed experimental rigs. A number of surveillance specimens are periodically extracted and tested to evaluate the changes in fracture toughness properties of the vessel as function neutron fluence. The surveillance testing results of test campaigns performed until 2015 were published previously in [1, 2]. The current paper presents fracture toughness and SEM results from the recent surveillance campaign performed in 2017. The fracture toughness specimen tested in this campaign received a thermal neutron fluence of 13.56 x1026 n/m2, which is ∼8.9 × 1025 n/m2 more than the thermal fluence received by the specimen tested in SURP 2015 campaign. These results from this campaign have shown no change in the fracture toughness from the values measured in the previous SURP campaign. The SEM observations are performed to study the fracture surface, to measure (by WDS) the transmutation Si formed near crack tip and to investigate various inclusions in the microstructure. SEM fracture surface investigation revealed a tortuous (bumpy) fracture surface constituting micro-scale dimples over majority of the fracture area. Islands of cleavage facets and secondary cracks have been observed as well. EDS analysis of various inclusions in the microstructure revealed presence of Fe rich inclusions and Mg-Si rich precipitates. Additionally, inclusions rich in Al-Mg-Cr-Ti were identified. Finally, changes in mechanical properties of Al 5154-O alloy with an increase in neutron fluence (or transmutation Si) are discussed in correlation with SEM microstructure and fracture morphology observed in SEM. TEM investigation of precipitate microstructure is ongoing and those results will be published in future.
Comparative Risks of Hydrostatic and Pneumatic Pipeline Testing
Authors: Simpson David A. 
Published: November 2019

Abstract
An important step in a pipeline-construction project is confirming that the piping and facilities are adequate for the expected operating pressures. This confirmation is done via a static strength test using a test fluid. All fluids have mass and internal energy. Fluids under pressure have significantly elevated internal energy. All fluids are compressible to some greater or lesser extent, and the fluid added to raise the pressure of the fluid in the bulk volume adds significant energy. The raw mass of a fluid must be considered when evaluating terrain elements and support elements (i.e., pipe stands and pipe racks). The selection process for a test fluid should always endeavor to minimize the total risk of the entire process.
There is guidance in the primary pipeline design/construction codes (e.g., ASME B31 series) for many of the important considerations for managing the risk associated with the tests required to perform this confirmation of fitness for purpose. This code-guidance has historically not shown a clear preference for the selection of one particular test-medium over another. Some jurisdictions have written regulations that step away from ASME guidance and do show a clear preference for hydrostatic testing over pneumatic testing. This preference manifests itself in several ways, but the primary representation is the requirement in statutes and regulations that a pneumatic test have an “exclusion zone” around the test to reduce the risk of injury during the test. These documents tend to not have an exclusion-zone requirement for hydrostatic tests.
This paper is undertakes to demonstrate the relative risks of liquid vs. gaseous test media and presents a background of why pneumatic tests have been singled out by regulators as higher risk and shows why this regulatory preference can result in actually increasing risk rather than decreasing it.
Analysis of the Gasket Damage and Sealing Performance for the Thread Ring Block Heat Exchanger
Authors: Zhuang Fakun , Sui Wen , Xie Guoshan , Shao Shanshan , Han Zhiyuan , Liu Wen 
Published: November 2019

Abstract
The thread ring block heat exchangers, served at the high temperature and pressure, are the key equipment in the petrochemical industry. Due to the severe operational conditions and unsuitable assemble, internal leakage problem commonly occurs, especially for the seal gasket between the tube sheet and shell. Many failed gaskets are collected. Through a series of experiments including chemical composition, metallographic analysis, SEM and fracture analysis, the gasket damage and leakage causes are analyzed. For further interpretation, the gasket stress analysis is completed by the finite element method. It shows that the gasket stress is a main factor that affects the sealing performance for the thread ring block heat exchanger. Under long term operation at high temperature and pressure, the gasket stress between the tube sheet and shell becomes loose and creep. The gasket material also deteriorates with increasing time. Therefore, in order to prevent the internal leakage, the stress should be controlled in an appropriate range. And periodical inspection must be performed.
Comparison and Analysis of Effective Guided Wave Standards Between GB and ASTM
Authors: Ding Ju , Zhang Min , Liu Shu-hong , Tang Chen-huai , Zhu Xu-chen , Tang Deng-chao , Yang Yu-qing 
Published: November 2019

Abstract
This paper discusses four different ultrasonic guided wave standards. Three of them are China’s national standards or industry standards: GB/T 31211-2014 “Nondestructive Testing Ultrasound Guided Wave Detection”, GB/T 28704-2012“Non-destructive testing—Test method for ultrasonic guided wave testing based on magnetostrictive effects”, and DL/T 1452-2015 “Thermal Power Pipeline Ultrasound Guided Wave Detection”. The another one is ASTM E2929:“Standard Practice for Guided Wave Testing of Above Ground Steel Piping with Magnetostrictive Transfusion”. Through six aspects in this article, including testing application scope, preliminary requirements, standard specimen and comparative specimen, distant amplitude curve and time gain curve, the existing difference between China and America is obvious and diversity. It is necessary to explore the underlying reasons for the connection of Chinese code and international code in the field of Non-destructive testing. During the standardization, anyone of the standard should be actually compared on the presentation of chart, and the verification and comparison of results, and lists the similarities and differences of each part based on GB31211.
This paper provides reference for China to integrate with foreign standards in the field of ultrasonic guided wave detection of pressure vessel and pipelines.
An Optimized Heat Treatment Process to Reduce the Weld Residual Stress by Auxiliary Heating
Authors: Luo Yun , Gao Teng , Jiang Wenchun 
Published: November 2019

Abstract
Local post welding heat treatment (PWHT) is a popular method to reduce the residual stress of bigger weld structures. In this paper, the weld residual stresses before and after local PWHT were investigated. The results show that there are larger axial stresses concentration in weld toe and an inconsistent deformation along axial direction during heating stage which may leads to crack. The residual stresses in outer surface are decreased greatly after local PWHT. An optimized local PWHT with auxiliary heating (AH) temperature 800°C and width 800mm were proposed. The axial stress and deformation inconsistent in weld can be reduced by AH, thus leads to the reduction of crack risk in weld toe.
Development of New Design Fatigue Curves in Japan: Discussion of Effect of Surface Finish on Fatigue Strength of Nuclear Component Materials
Authors: Nakane Motoki , Wang Yun , Hatoh Hisamitsu , Yamamoto Masato , Hirano Akihiko , Hayashi Kentaro 
Published: November 2019

Abstract
Based on the world wide fatigue test database, The Design Fatigue Curve (DFC) Phase 1 and 2 subcommittees established in The Japan Welding Engineering Society (JWES) have been developed new design fatigue curves which are applied for the nuclear component materials, in air environment. The effects of the design factor, such as mean stress, size effect and surface finish, etc. on the fatigue curves are also discussed with the fatigue database in order to construct fatigue evaluation method for the new design fatigue curves. The subcommittees also have studied the applicability of newly developed fatigue evaluation method to the nuclear component materials.
This paper reports the fatigue test results of machined finished small-scale test specimens which are used for the verification of proposed fatigue evaluation method. The materials subjected to the fatigue tests are austenitic stainless steel SUS316LTP, low-alloy steels SQV2A and SCM435H, and carbon steel STPT370. Specimens finished with lathe machining are subjected to the tests. The planed maximum height roughness of the specimen are 25 and 100 μm. The fatigue test results show that the surface finish effect on the fatigue strength in the high cycle region of the austenitic stainless steel can be negligible. On the other hand, fatigue strength of the carbon steel and low alloy steel is decreased as increasing the surface roughness of the specimen. Especially, decrease of fatigue strength for the specimens with more than 100 μm maximum height roughness is larger than that of conventional estimation. It is presumed that severe roughness introduced by lathe machining tends to behave as notches and increase the stress concentration at the specimen surface, and resulted in unexpected decrease of fatigue strength.
Load Normalization Method Accounting for Elastic and Elastic-Plastic Crack Growth
Authors: Wallin Kim , Xu Steven 
Published: November 2019

Abstract
A single specimen technique to estimate crack length, standardized in ASTM E1820, is the so called load-normalization technique, also known as the Key-curve technique. The method is based on the separability between deformation and crack length. This means that if the load is normalized by a suitable function of crack length, the result will be a single crack length independent load-displacement curve. If this “Key”-curve is known, then based only on load and displacement information it is possible to estimate the corresponding crack length.
The load normalizing method assumes a plastic response of the specimen during crack growth. If there is crack growth already in the elastic regime, non-linearity in the load-displacement record is not due to plasticity, but due to the crack growth. In this case the standard load-normalization method does not work since it assumes that the non-linearity is due to plasticity or crack tip blunting. Such materials require a modified approach.
Here, a modified load normalization method accounting for possible elastic crack growth is presented. The method is shown to produce realistic crack growth estimates regardless of plasticity level of the specimen. The method applies an improved load normalization equation compared to the one presently used in ASTM E1820.
Dynamics of a Pipe Subjected to Internal and Confined External Flow
Authors: Païdoussis Michael P. , Abdelbaki Ahmed R. , Butt M. Faisal Javed , Moditis Kyriakos , Misra Arun K. , Nahon Meyer 
Published: November 2019

Abstract
We consider a hanging cantilevered pipe conveying water within a water-filled container; the upper portion of the pipe is surrounded by a rigid cylindrical tube of larger diameter, forming an annular fluid-filled region around the pipe. Two flow configurations are investigated : (a) water enters the pipe at its clamped end and flows downwards, discharging at its free end into the container; the fluid exits the container by flowing upwards in the annulus and out; (b) the reverse flow arrangement: water enters the system at the upper end of the annulus and exits by flowing upwards in the pipe. The dynamics of the system is studied theoretically and experimentally for both configurations. The analytical models utilized are outlined and the experiments are described. Theory and experiment find that the system loses stability at sufficiently high flow velocity by flutter or static divergence.
Cyclic Plasticity Analysis of Welded Joint With Welding Residual Stress Using the Direct Method
Authors: Puliyaneth Manu , Chen Haofeng , Luan Weiling 
Published: November 2019

Abstract
To meet the growing energy demands, the power sector continuously strives at enhancing the efficiency of its power plants by increasing the operating temperature. Under cyclic loading conditions, this leads to creep-cyclic plasticity driven damage mechanisms such as cyclically enhanced creep, creep enhanced plasticity and creep ratcheting. A detailed understanding of creep and related damages is therefore essential for predicting any potential failure mechanisms and ensuring confidence in the safe-working of the components. This becomes particularly difficult and challenging in the presence of welds due to two main reason; a) presence of different material zones, namely parent metal, weld metal and heat affected zone; b) introduction of residual stress during welding. An extended Direct Steady Cycle Analysis within the Linear Matching Method (LMM) framework has been previously developed to consider the full interaction between creep and cyclic plasticity. This paper presents the basic theory and an overview behind the LMM framework along with a new application of a welded flange, considering for the first time the effect of residual stress due to welding. A 3D finite element model is adopted for the flange, and it is subjected to a constant pressure and cyclic thermal load of varying dwell. The effects of welding residual stress on the creep-cyclic plastic response of the welded flange are investigated. Additional parametric studies considering different levels of the applied load and dwell period are performed. The results reflect the ease of using LMM over conventional inelastic analysis.
The Effects of Bolt Tightening Sequences on the Mechanical Behaviors of Gasketed Flange Joint
Authors: Chang Chia-Lung , Huang Jung Xian 
Published: November 2019

Abstract
During tightening bolts on the flange joint, a load is applied on each bolt. The deformation and stress on joint parts vary with magnitude and location of applying bolt forces. Therefore, sequence of tightening bolts has effects on the deformation and accumulated stress on joint parts. Finite element method is used to model the flange joint and to simulate effects of bolt tightening sequence on the deformation and stress on joint parts. The model includes bolts, nuts, raised face flanges, and gasket. Contact conditions are set on contact surfaces between contact parts. 3D elements are used to build the model. In order to prevent leaks, the bolt load and gasket pressure should be uniform. The accumulated stress of bolts and gasket are calculated. The deformation of gasket and flange are also simulated. The model is used to simulate the stress and deformation of flange joint generated by various bolt tightening sequences. The optimal tightening sequence is selected by that the variation of accumulated stress on gasket is the least.
Experimental and Simulation Study on Effective Hydrogen Diffusivity of Cold-Worked Type-304 Austenitic Stainless Steel
Authors: Sezgin Jean-Gabriel , Takatori Daichi , Yamabe Junichiro 
Published: November 2019

Abstract
This study presents some measurements of the effective hydrogen diffusivity in a cold-rolled, Type-304 stainless steel. Steel plates rolled under various cold working (CW) ratios were prepared. Disk specimens, referred to as LT and SL specimens, were sampled from the plates to determine the diffusivity. The rolling direction is perpendicular to the thickness direction for LT specimens and parallel for the SL specimens. Fraction and distribution of α′ phase islands resulting from strain-induced martensite were characterized by electromagnetic induction (EMI) method and electron backscatter diffraction (EBSD) analysis, respectively. The diffusivity of the LT and SL specimens exposed to high-pressure hydrogen gas was determined experimentally through desorption methods. Hydrogen permeation tests for LT and SL specimens were simulated using the finite element method (FEM) by considering a model material containing an inhomogeneous distribution of α′ phase islands. The EMI measurements established that the fraction of the α′ phase increases with the CW ratio. The phase maps from the EBSD analysis revealed an important difference in α′ phase distribution on planes perpendicular and parallel to the rolling direction (LT and SL planes). For CW = 60%, the diffusivity of the SL specimen was five times larger as compared to the LT specimen, although the fraction of the α′ phase is equal. The simulation of the permeation tests also showed a strong difference in the diffusivity between both specimens, and therefore supports the experimental results. Both experiments and simulations suggested that the anisotropic nature of the effective hydrogen diffusivity (in LT and SL specimens) could be attributed to the inhomogeneous distribution of the α′ phase islands in the cold-rolled material.
Enhancement of Uplift Displacement of Tanks due to Out-of-Round Deformation of Cylindrical Shell
Authors: Miyauchi Yoshiyuki , Taniguchi Tomoyo , Nakashima Teruhiro , Hongu Junichi , Okui Daisuke 
Published: November 2019

Abstract
Two unanchored vinyl chloride scale tank models, whose diameter, height and thickness of their shell and base were 860 mm, 400 mm and 0.5 mm respectively, were set on a shaking table for experiencing the horizontal motion. These scale tank models satisfy law of similarity to have an equivalent strain under the action of loads.
The first scale tank model has no stiffeners on its cylindrical shell that allows out-of-round deformation of the cylindrical shell during the shaking table test. To understand effects of the out-of-round deformation of the cylindrical shell on the tank uplift, the sweeping test is carried out. The Operational Modal Analysis clarifies that the out-of-round deformation of the cylindrical shell enhances the uplift displacement by denting a part of cylindrical shell.
The second scale tank model has the multi-stage stiffeners on its cylindrical shell to prevent its out-of-round deformation during the shaking table test. The primary purpose of the second test is to verify applicability of the explicit finite element analysis for analyzing the tank rocking motion. The time history of the uplift displacement of the tank base during a seismic excitation is measured and compared with that computed by the explicit finite element analysis. The comparison shows that the explicit finite element analysis adequately reproduces the tank rocking behavior.