bluuebunny/crossref_metadata_2025 huggingface dataset:
Plan of a Shaking Table Test on a Piping System Model for Verifying the Fracture-Control Concept
Authors: Nakamura Izumi , Kasahara Naoto
Published: November 2022

To mitigate the severe effects in the beyond design basis accident (BDBA), the concept of fracture control was proposed in the previous study. The idea of the fracture control is to manage the accident consequence by controlling to cause minor failure prior to the fatal failure.

Taking the piping system as an example, boundary failure should be prevented under the BDBA condition, whereas the minor failure, such as support failure which does not affect the function of the piping system, can be acceptable.

To realize the fracture control concept on piping system, shaking table tests on piping systems with support are planned. As the first step of the attempt, fundamental experiment on relatively simple piping system and support configuration was conducted. In this experiment, pipe elbows made of simulation material (lead-antimony alloy) were used, and the support was modeled by a plate. Through the experiments, the fracture of support successfully occurred prior to the large deformation of pipe itself. The results showed that the fracture control may be possible when the fracture of support occurred prior to the failure of pipe itself, and the ratio of the input frequency to the specimen’s natural frequency (fR) be over 1.0 after the support failure. The test results demonstrated the possibility of fracture control concept by support failure.

As the next step of the attempt, shaking table test on more realistic piping system, which is named as validation test, is now prepared. The preliminary analysis shows that the inelastic behavior of support is expected.
Assessment of Gaseous Detonations in Pressure Vessels
Authors: Pease Derrick , Abatt George , Clutter Keith
Published: November 2022

This paper covers several practical engineering aspects of gaseous detonations in pressure vessels: (1) Description of the phenomena and physics of deflagration, detonation, deflagration-to-detonation transition, and reflections in pressure vessels; (2) Development of pressures and loads caused by the detonation process in pressure vessels; (3) Analytical evaluation techniques and assessment criteria in the context of the ASME B&PV Code Section VIII. There are many factors that govern the type and severity of gaseous detonations in pressure vessels including gas composition, initial pressure, and ignition location within the pressure vessel. This paper addresses several of these factors, how they affect the resulting pressure transients in the vessels, and how the pressure transient loads can be applied to the Abaqus structural model. The method of load application is easily adapted to other FEA software packages. The structural integrity of the vessel is evaluated using the Abaqus Johnson-Cook plasticity model and associated strain limit damage criterion. The paper is specifically focused on pressure vessels where gaseous detonations have unique characteristics compared with more constrained space such as piping systems. A companion paper (PVP2022-84291) addresses the unique characteristics of gaseous detonations in piping systems and pipelines.
An Evaluation of Probabilistic Integrity Assessment Codes
Authors: Guo Lingyun , Niffenegger Markus
Published: November 2022

In recent years, a large number of failure assessment models (FAMs), like SINTAP, BS7910 and API 579 have been developed to evaluate the structural integrity of pipelines. Based on them, various software, such as PRO-LOCA, PROST, xLPR, etc, have been established to evaluate the safety and reliability of pipelines. However, which of these codes fit best the user’s requirements is a difficult problem because it depends on scientific as well as on personal criteria. Therefore, in this paper, we propose several multiple evaluation criteria to discuss the integrity assessment codes. Furthermore, we apply mathematical methods to evaluate the prediction performance (PP) of the codes PRO-LOCA and PROST.

The PP covers seven criteria: correlation, multimodality, dispersion, risk, conservativeness, robustness and accuracy. The correlation, multimodality and dispersion reflect the stability of the predicted results, while risk, conservativeness, robustness and accuracy illustrate distributional location characteristics (DLC) of the prediction accuracy (PA).
Clearing Effect of Blast Loads from PVBs
Authors: Geng Jihui , Thomas J. Kelly
Published: November 2022

Blast waves from explosion sources such as a pressure vessel burst (PVB) exhibit both positive and negative phases, and the relative magnitude of the positive and negative phases is a function of standoff distance from the explosion source to the target of interest. When an incident blast wave reaches a target building, the blast wave will be reflected off the front wall (i.e., that facing the blast source). Both the blast wave positive and negative phases are affected by this reflection process. A fully reflected blast wave would be produced if the incident blast wave reflected off an infinitely tall and wide wall in a normal orientation. However, when an incident blast wave reflects from a facing wall of finite size, rarefaction waves are created at the edges of the wall and roof, which then sweep inward across the wall. The rarefaction waves result in a clearing effect for both the positive and negative phases. Clearing relieves some of the applied positive phase blast load on the reflected wall. However, clearing may either relieve or enhance the applied negative phase blast load, depending on the blast wave profile and the wall dimensions.

This paper focuses on the determination of negative phase clearing as a function of blast wave and structure parameters. Blast load adjustment factors (i.e., ratio of cleared to fully reflected blast loads) are introduced to characterize blast clearing as a function of these parameters. The purpose of the evaluation described in this paper was to generate a database of the blast clearing for engineering modeling of blast-structure interaction.
Assessment of Gaseous Detonations in Piping Systems and Pipelines
Authors: Clutter Keith , Pease Derrick , Antaki George
Published: November 2022

This paper covers several practical engineering aspects of gaseous detonations in piping systems:

(1) Description of the phenomena and physics of deflagration, detonation, deflagration-to-detonation transition and reflected deflagration-to-detonation transition in piping systems;

(2) Development of transient pressures and loads caused by the detonation process in piping systems and in-line components;

(3) Analytical evaluation techniques and assessment criteria in the context of the ASME B31 Codes. There are several factors that govern the type and severity of gaseous detonations in piping systems including gas composition, initial pressure and ignition location within the piping system. This paper addresses many of these factors and how they affect the characteristics of gaseous detonations in piping systems. The critical characteristic used to determine the structural integrity of piping systems to withstand a detonation is the transient pressure history inside the piping. This paper addresses how to develop such transient pressure histories that can then be readily applied to analytical structural models. There are several methods that can be used to apply a transient pressure history to a structural model of a piping system. This paper addresses some methods that have been used to apply this type of loading to finite element models in Abaqus. These methods could be easily adapted to other FEA software packages. There are also several evaluation methods that can be used to determine the structural integrity of the piping system. This paper addresses some of the more advance methods involving plastic deformation with strain limit damage and explicit time-history solvers. Finally, this paper is specifically focused on piping systems and pipelines where gaseous detonations have unique characteristics compared to more open volumes such as tanks and vessels. A separate paper (PVP2022-84269) addresses the unique characteristics of gaseous detonations in pressure vessels.
Research on Flexural Performance of Curved Carbon Fiber Laminate Composites
Authors: Li Hongfei , Chen Zhiping , Ge Peng , Miao Hao
Published: November 2022

As a clean and efficient secondary energy, hydrogen energy is of great significance for building a clean, low-carbon, safe and efficient energy system. At present, high-pressure gaseous hydrogen storage systems for vehicles mostly use carbon fiber reinforced composite materials as the pressure-bearing materials of hydrogen storage vessel to obtain a lighter mass, so as to ensure the hydrogen storage system has a higher hydrogen storage density. However, unlike traditional steel hydrogen storage vessel, carbon fiber composite hydrogen storage vessel has low rigidity and is prone to bending and deformation during manufacture and use, which can cause safety accidents. Most of the previous studies on mechanical properties have focused on flat laminates, which are of limited help to the study of hydrogen storage vessel. In view of this situation, this work fabricated the curved carbon fiber laminates with the same manufacturing process as the hydrogen storage vessel and investigated their flexural performance using a combination of experimental and finite element methods. The bending experiments of curved carbon fiber laminates at different angles were carried out. And the finite element model for flexural performance prediction of curved carbon fiber laminates was established through validation against the experimental results. A parametric study was further performed to analyzed the influence of carbon fiber winding angle on the flexural performance. This work will provide reference and basis for the subsequent research on the flexural performance of carbon fiber composite hydrogen storage vessel.
Fluid-Structure Interaction Analysis of a Peristaltic Pump by Using Numerical and Experimental Methods
Authors: Li Qingye , Zong Chaoyong , Zhang Jianhua , Zhang Yanfeng , Song Xueguan
Published: November 2022

Peristaltic pump is an important transport device which is widely used in industries involving pharmaceutical, petrochemical, biomedical, and food processing. For designed and/or optimized purpose, it is necessary to have a thorough understanding the mechanism of its dynamics. For this purpose, both numerical and experimental investigations have been performed in this paper. In the numerical study, a numerical model concerning two-way Fluid-structure Interaction (FSI) phenomenon is developed, where the Mooney-Rivlin hyper-elasticity model and dynamic mesh technique are employed to simulate a complete operating period of a peristaltic pump. For model verification, a series of experimental tests are performed and the results of the simulation and the tests were compared, which showed a good agreement. With the validated model, a detailed velocity and pressure distribution of a working period of the peristaltic pump is obtained, the mass flow rate is analyzed to illustrate the mechanism of the flow fluctuations.
Numerical Simulation of Complex Fracture Network Propagation in Shallow Bright-Type Coal Seams in Hancheng Block, China
Authors: Zhao Haifeng , Li Xuejiao , Wang Xiaohua , Li Pengyue , Zhu Likai , Zhang Qingjiu
Published: November 2022

The generation of complex fracture networks by hydraulic fractures activating and connecting natural cleats and fractures during hydraulic fracturing is of great significance to the development of coalbed methane (CBM) reservoirs. Hydraulic fracturing physical simulation experiments of shallow bright-type coal seams in Hancheng block were conducted. Based on the experiment results, fluid-solid interaction theory, and discrete fracture network model, a 3D fracture network model of bright-type coal seams was developed. Fracture network propagation behaviors under different rock mechanical properties and fracturing operation parameters were investigated. Sensitivity analysis of the influencing factors of fracture network propagation was performed with the grey correlation method. The results show that a complex fracture network dominated by the main fracture is formed after hydraulic fracturing in bright-type coal seams. Fracturing operational parameters (fracturing fluid displacement and viscosity and perforation location) are the main controlling factors of fracture network propagation, whereas Poisson’s ratio of the coal seam has a relatively weak effect on the fracture network. As the elastic modulus difference between the roof and coal seam increases, the fracture network conductivity and simulated reservoir volume (SRV) first increase and then decrease. When the elastic modulus difference between layers is 10 GPa, the conductivity and SRV achieve their maximum values. With increasing displacement, the length, height and SRV of the fracture network increase linearly, but the conductivity decreases. Large displacement is beneficial to the formation of a complex fracture network in bright-type coal seams. The optimized fracturing fluid viscosity is 20 mPa·s. The optimal perforation location is near the formation interface. The results could provide theoretical guidance for the design and optimization of efficient fracturing of CBM reservoirs.
Research on On-Line Monitoring and Evaluation Method of Thermal Insulation Performance of Vehicle LNG Gas Cylinder
Authors: Shi Kun , Zhou Yunyi , Hu Hangjian , Duan Zhixiang
Published: November 2022

Driven by energy structure optimization, environmental pollution control and climate change constraints, the development of new energy vehicles has become a global trend, LNG (Liquefied Natural Gas) vehicles whose key energy storage equipment is the low-temperature insulated gas cylinders are one of the most important components. The feasibility of online health monitoring of low-temperature insulated gas cylinders for vehicles is verified in this paper and an online monitoring device for vehicle gas cylinder thermal insulation performance parameters is designed and implemented. Together with the wireless communication technology and the online monitoring device, the remote management platform for gas cylinder safety and health can be constructed. Through experiments, the static evaporation rate and holding time of low-temperature insulated gas cylinders with different filling rates and vacuum degrees were measured and the pressure boost curve before and after vacuum loss was obtained. By analyzing the experimental data, it is found that the rate of pressure rise of the cylinder is different before and after vacuum loss, so the safety condition of the cylinder can be evaluated. Compared with traditional vehicle gas cylinder inspection, it can save inspection time by monitoring the rate of pressure rise instead, which can realize the improvement of the efficiency of gas cylinder inspection and the timeliness of equipment risk warning.
Development of Material Mechanical Properties Testing Platform for Liquid Hydrogen Temperature Zone
Authors: Feng Yufeng , Wu Yingzhe , Kuang Jiyong , Gu Chaohua , Zheng Jinyang , Hua Zhengli , Gao Ruizhe
Published: November 2022

Many materials exhibit a ductile-brittle transition as the temperature decreases. Liquefied gas and cryogenic equipment become more and more widely used in the industry, especially the accelerated commercialization of the liquid hydrogen industry. However, there is a lack of cryogenic mechanical property testing platform and published material mechanical property data below the liquid nitrogen temperature zone (77K). The development of cryogenic mechanical property testing platform is the basis for obtaining cryogenic mechanical property data of materials.

Therefore, based on the existing cryogenic mechanical testing platform of the team, a system-level design of the modified cryogenic mechanical testing platform was designed and implemented. The modified platform is named Mechanical Performance Testing Platform for Liquid Hydrogen Temperature Zone and it is using a Gifford-Mcmahon refrigerator to provide cryogenic cooling and a refrigerated helium circulation loop to transfer the cooling to the specimen effectively. The lowest test temperature can reach the liquid hydrogen temperature range 20K. Finally, tensile tests of S30408 (Equivalent to UNS S30400) austenitic stainless steel at 20K and 77K are carried out by the Testing Platform.
The Study of Impact Damage of Carbon Fiber Wrapped Cylinder With Aluminum Liner Based on X-Ray Digital Radiography
Authors: Chai Sen , Huang Liang , Dai Huaibei , Bo Ke , Li Xiang , Deng Guide , Huang Qianghua
Published: November 2022

With the development of hydrogen fuel cell vehicles, Carbon Fiber Wrapped Cylinder with Aluminum Liner are widely used in the field of the on-board storage of compressed hydrogen. Impact damages are common in Carbon Fiber Wrapped Cylinder with Aluminum Liner because the composite laminate structure is sensitive to impact load. In this work, the DR method with the technology of compensation block is used to detect impact damage of Carbon Fiber Wrapped Cylinder with Aluminum Liner, and analyzes the expansion of impact damage after different number of pressure cycles. The main damage of Carbon Fiber Wrapped Cylinder with Aluminum Liner caused by impact are delamination of carbon fiber overwrap, debonding between cylinder liner and carbon fiber overwrap, and bulge inward of aluminum liner, and these damages become more serious as the impact energy increases from 500 J to 1500 J. As the pressure cycle test is performed to the Carbon Fiber Wrapped Cylinder with Aluminum Liner, the impact has a serious effect on the fatigue performance of the cylinder. In addition, the debonding between the cylinder liner and the carbon fiber overwrap and the bulge inward degree of the aluminum liner are reduced due to the internal pressure. When the impact energy is low (i.e., 500 J), the pressure cycle has no significant influence on the delamination defect of carbon fiber overwrap. Besides, under the high impact energy conditions (i.e., 1000 J and 1500 J), the delamination defect of the overwrap in the impact center appears obvious expansion with the pressure cycle, while the delamination defect at the impact edge does not propagate obviously.
Reconstruction of Phased Array Ultrasonic Testing Image of Through Hole Based on Finite Element Analysis
Authors: Feng Ying , Fang Haiqing , Guo Weican , Jiao Di , Shi Jianfeng
Published: November 2022

As a most feasible defect detection method, phased array ultrasonic testing (PA-UT) plays an important role in nondestructive testing of pressure vessels and piping for its high detection efficiency. It’s necessary to obtain the size and position of defects or features for safety assessment to ensure the safe running of equipment if there is a defect. However, PA-UT suffers from image distortion due to acoustic attenuation and dispersion, as well as problems with imaging principle, which usually leads to errors when measuring the size and position of detected features. In this paper, the standard polyethylene block with a through hole was tested by PA-UT and the PA-UT images of artificial defects were obtained. At the same time, the PA-UT images were simulated by combining finite element analysis of the PA-UT process as well as the ultrasonic imaging algorithm. By comparing the test results and simulation results, the influence of sector scan angle and the number of elements in the active aperture on image distortion was analyzed. Moreover, based on the simulation method, the PA-UT images were post-processed to eliminate the distortion and reconstructed to be closer to the real size. This method could be further used for improving the imaging quality of the PA-UT testing system.
Comparison of Technical Standards Between Buried and Above Ground Polyethylene Pipe in the Application of Nuclear Power Plant
Authors: Shi Jianfeng , Cao Yuhua , Jiao Di , Yu Fa , Li Yu , Jiang Jiayin , Zheng Jinyang
Published: November 2022

High-density polyethylene (HDPE) pipes have been used in essential service water (ESW) systems of nuclear power plants (NPP) for years. Some NPPs use buried HDPE pipes, while some others use above ground (gallery-installed) HDPE pipes, and this paper will discuss the differences in the design methods of these two construction methods in related technical standards. The design requirements and related load types of buried and above ground HDPE pipes in safety-related Class 3 service water or cooling water piping systems are compared. Pipeline models under different load types are introduced, including model assumption, material simplification, boundary conditions, interactions, etc. The differences in design loads are summarized, i.e., soil and surcharge load, negative internal pressure, flotation due to flood of buried HDPE pipe, and axial forces due to different supporting or fixing methods of above ground HDPE pipe. The design methods of buried and above ground HDPE pipeline are discussed and compared, i.e., design of mechanical load, temperature load, non-repeated anchor movements and seismic load. A case study is presented by using different technical standards of buried and above ground HDPE pipes. This work can provide a reference for the selection of HDPE pipes for safety-related Class 3 service water or cooling water piping systems in different NPPs.
Experiment Study on Acoustic Emission of Different Energy of Impact-Damaged Fully-Wrapped Composite Gas Cylinders With Non-Metallic Liner
Authors: Cheng Liang , Li Qinghua , Cui Dongliang , Bo Ke , Li Xiang
Published: November 2022

With the rapid development of clean energy, type 4 cylinders will be widely used in the world due to their many attractive advantages. Impact damage, cuts and abrasions are the common damage modes of type 4 cylinder. Impact damage affects the safety of cylinders, but few studies are involved in the assessment of impact damage for type 4 cylinders.

In order to evaluate the safty state of cylinder with impact damage, drop tests and burst tests were carried out for type 4 cylinders. The effect of different degree of impact damage to cylinder burst pressure cylinder was obtained. AE tests were carried out on undamaged cylinder and impact-damaged cylinders with different impact energy. The essential characteristics of AE signals for different energy levels of impacted cylinders were obtained.

The results showed that there was a critical impact damage at which cylinder burst pressure started to decrease. There were obvious changes of AE test results when peformed on impacted cylinders with different impact energy. AE cumulative hit number correlated well with the degree of impact damage of type 4 cylinder. AE cumulative hit number and signal energy were two critical parameters for evaluating the cylinder with impact damage. It demonstrated that AE test was efficient and could be used to differentate a cylinder which has a loss of key performance resulted from impact damage.
Data-Centric Structural Integrity Assessment and Risk-Informed Asset Management Using Operational Data and Probabilistic Updating
Authors: Martin Michael , Marshal Robert , Reed Peter
Published: November 2022

The UK EASICS (Establishing Advanced Modular Reactor Structural Integrity Codes and Standards) programme has developed guidance to inform the development of codes and standards for application to the structural integrity assessment of future high-temperature designs [1]. A key aspect of the EASICS guidance describes the use of probabilistic methods in the context of a data-centric approach that can use data from all stages of the product lifecycle from design and manufacture through operation, maintenance and decommissioning to update the structural integrity assessment.

This paper provides a summary of the EASICS data-centric approach before focusing on the operational phase of the product lifecycle and the use of data derived from plant monitoring and In-Service Inspection. The numerical analysis of a prototypical geometry with a postulated initial defect and set of simulated operational histories is used to demonstrate how such data can be used to manage the future inspection strategy on a risk-informed basis. A starting point of a required number of operational events, but unknown and arbitrary future operational sequence of events is considered.

The structural reliability is calculated and updated through-life using the Monte Carlo random sampling method in conjunction with a selection of probabilistic updating techniques, including Bayesian inference.
An Active Magnetic Saddle Based on Electro-Permanent Magnetic Adhesion Mechanism
Authors: Zhang Hongsheng , Li Yanbin , Guo Kai , Jiang Jianxv
Published: November 2022

In this paper, a novel transport technique for pressure vessels based on electro-permanent magnet (EPM) technology is proposed. The magnetic force and the resulting transport gripping force (TGF) are applied by controllable permanent magnets rather than conventional electromagnet or permanent magnet technology, and the current is only required at the moment of loading or unloading the TGF. The EPM system is convenient in control, and low in energy consumption. The experimental device including magnetic chuck, web of foundation girder and other components is constructed based on the EPM characteristics and requirements of transported equipment. The EPM units are used to generate magnetic force to realize loading and unloading of TGF. The principles and advantages of EPM transport technique are first elaborated with theoretical derivation and magnetic field simulation. Then, a series of experiments such as electrical circuit, magnetic field and tensile test were performed for the EPM chuck and magnetic saddle. It is demonstrated that the TGF applied by the designed system is large enough for the transportation of the pressure vessel. Also, the energy saving is significant using the EPM transportation system.
Effect of Normalizing Cooling Rate on Impact Toughness of ASME SA – 350 LF2 CL1 Forgings
Authors: Hernández Soto R. , Gómez de Salazar J. M.
Published: November 2022

This paper intends to contribute to a better understanding of how normalizing cooling rate affects toughness of SA – 350 LF2 Class 1 forgings. This is a sensitive material widely used in pressure vessels fabrication when toughness requirements are applicable.

Three pieces from the same forging were normalized at 870°C for two hours. Each of them was subjected to a different cooling rate from normalizing to room temperature, being the temperature in the center of the piece registered by thermocouples every two seconds. Test specimens were extracted for impact testing at −46°C and metallographic examination. Subsequently, the normalized samples were cut out in two and subjected to two simulated post weld heat treatment at 630°C. Further specimens for metallographic characterization and impact testing were taken.

It can be concluded that normalizing cooling rate has a pivotal role in the morphology of pearlite, and hence in its ability to offset the deterioration of toughness in the post weld heat treatment due to iron carbide precipitation by means of pearlite spheroidization.
Ductile Tearing Prediction of Ferritic Pipes by GTN Model for ATLAS+ European Project (Report 2)
Authors: Kumagai Satoshi , Hojo Kiminobu , Hirota Takatoshi , Kawanishi Keiji
Published: November 2022

The European project “Advanced Structural Integrity Assessment Tools for Safe Long Term Operation (ATLAS+)” is aiming to achieve a reasonable balance between safety and long term operation of nuclear reactor pressure coolant boundary systems. In the project, the Work Package 3 deals with development and validation of finite element analysis (FEA) using the Gurson-Tvergaard-Needleman (GTN) model to predict a ductile crack growth behavior of a pipe structure from those of laboratory specimens such as SE(T) and C(T) specimens. By using the parameter sets of the GTN model obtained by other members in the project, the authors predicted the fracture behaviors of three pipes with a circumferential through-wall crack or a circumferential outer surface crack by the four-point bending test conducted by a member of the project. As a result, the predicted maximum loads agreed with those of experiments within the error of 2.2 %, and the predicted ductile crack growth amounts were nearly equal to those on the fractured surface. In addition, the J-resistance of the pipe with a though-wall crack was calculated by the FEA by the node release technique with a crack growth criterion according to the crack growth predicted by the GTN model. Consequently, the J-resistance of the pipe is 3.1 to 3.6 times larger than that of C(T) specimens, which means that a prediction by the conventional fracture mechanics has a lot of margin to the actual fracture behavior.
Fatigue Crack Growth Prediction of a Pipe With a Circumferential Surface Flaw Using ΔJ and Reference Stress Method
Authors: Hojo Kiminobu , Kumagai Satoshi
Published: November 2022

Fatigue crack growth calculation method beyond ΔK in codes and standards, like ASME Sec. XI or JSME rules for Fitness for Service has not been established even in Mode I. In the FDF-II Subcommittee of the nuclear research committee of the Japan Welding Engineering Society, an evaluation procedure for fatigue crack growth beyond small scale yielding using ΔJ has been investigated for several years. Since the evaluation procedure in the Subcommittee is to be incorporated into codes and standards, it should not be complex. Therefore the reference stress approach was tried to apply to calculate J-integral as a simplified procedure. Several formulae for J-integral calculation based on the reference stress approach were proposed by researchers. The authors joined the Subcommittee and performed finite element analyses for a sample problem to confirm the accuracy of those formulae, which were for a pipe with a circumferential part-through wall flaw subjected by bending load. The reference stress-based J, whose accuracy was confirmed by the authors, was applied to predict crack growth behaviors of pipes with a circumferential surface flaw under cyclic bending load conducted by other researches a decade ago. The difference of the failure cycles between the prediction and the experiment were nearly within a factor of 2. Since the verification of the simplified procedure was performed for just one case, more verification cases were needed to incorporate the procedure into codes and standards.
Study on the Manufacturing and Failure Modes of Type Ⅳ High-Pressure Hydrogen Vessel Liner
Authors: Kang Qiubing , Kuang Jiyong , Hua Zhengli , Li Yifan , Chen Weifeng , Peng Wenzhu
Published: November 2022

With the development of the hydrogen energy industry, type IV hydrogen vessels are widely used in hydrogen fuel cell vehicles, hydrogen storage for stationary and transportation due to their advantages of light weight, high hydrogen storage mass ratio and fatigue resistance. The, type IV hydrogen vessel is composed of a polymer liner, and carbon fiber impregnated with thermosetting resin is wound on the liner. The manufacturing process of polymer liner will affect the performance and forming cost of type IV hydrogen vessels. When pressurized, due to the hydrogen permeability of polymer materials, hydrogen will penetrate and dissolve into the material, and then emptying will cause the pressure difference between the interface between the liner and the composite material layers and the inside of the vessel, which may result in polymer liner blistered or collapsed. The current status of foreign molding process that may be used for the type IV hydrogen vessel polymer liner is firstly summarized. Then, according to the failure modes of type IV hydrogen vessel, the related experimental research, finite element analysis method and failure prediction model are summarized and analyzed, and the factors affecting blistering and collapse are discussed. Finally, further research on blistering and collapse failure of the type IV hydrogen vessel liner is prospected.
FEA Validation and Refinement of Alternative Nozzle Reinforcement Rules for Gasketed Plate Heat Exchangers
Authors: Nikic Milan , Srnic Djordje
Published: November 2022

This paper is an expansion of previously developed alternative nozzle reinforcement rules for gasketed plate heat exchanger (GPHE) end plates. The previous work on the alternative reinforcement rules for GPHE has been conducted by analytical means utilizing the basis of ASME BPVC Section VIII, Div. 1, Section UG-39, and the principles and data of a simply supported plate theory. As a part of the initial work, some assumptions had been left to be validated by Finite Element Analysis (FEA). The objective of this paper is to conduct the FEA validation of those assumptions and to further refine and expand the alternative reinforcement rules for GPHE.

The results of FEA show a good agreement with the initially developed analytical rules. The rules have further been expanded utilizing the same principles developed in the initial work and using additional data obtained by FEA. The expanded alternative reinforcement rules for GPHE, while being limited to the range of plate length to width ratio, are useful analytical means for design of GPHE end plates that may be used in lieu of more costly proof testing or FEA. In addition, the alternative reinforcement rules evaluate the reinforcement in the vicinity of nozzle openings resulting in an optimized design thickness of the GPHE end plates.
Analysis of Piping Components for High Temperature
Authors: Adibi-Asl Reza
Published: November 2022

ASME Section III Div. 5 provides design rules for high temperature applications involving deformations in the creep range. The latest Code edition is mainly focused on component design and guidelines for piping analysis and design is very limited. For piping analysis, the Code refers to ASME Section III Div. 1 NB-3600 rules along with specific requirements within Div. 5 design by analysis requirement. This paper reviews these requirements and further explores how these requirements can be utilized in piping analysis.
Study on Ductile Crack Extension and Fracture Behavior in Plate Specimen With a Semi-Elliptical Surface Crack Using a BWR Reactor Pressure Vessel Material
Authors: Hayashi Takahiro , Ogawa Takuya , Yoshida Shuichi , Itatani Masao , Saito Toshiyuki
Published: November 2022

Cases of stress corrosion cracking (SCC) in Ni-base alloy weld metals welded to the low alloy steel (LAS) in reactor pressure vessel (RPV) components have led to discussions on the possibility of SCC propagating into the RPV. In the previous study, the fracture mode of dissimilar metal welds (DMWs) of LAS and Ni-base alloy weld has been investigated by using a large-scale, heavy forged steel part named “bottom head ring” of the RPV, manufactured for a recent boiling water reactor (BWR). The fracture loads evaluated using the elastic-plastic fracture mechanics (EPFM) methodology have showed fairly good agreement with the maximum loads in the fracture tests on plate specimens with a semi-elliptical surface crack. All the fracture tests have successfully demonstrated the applicability of the fracture assessment methodology based on EPFM to the DMWs of RPV components.

In the fracture tests on the plate specimens, a periodic unloading condition was applied in order to obtain specimen compliance: inverse of the gradient in the load-displacement relationship under unloading. The compliances were evaluated from the crack mouth opening displacement (CMOD) data that have been obtained for large CMOD of more than 10 mm at fracture. The results of detailed evaluations of the ductile crack extension behavior based on the evaluated compliance indicated that the ductile crack extension occurred near the maximum load. Evaluations of the J–Δa relationships of the plate specimens based on the CMOD data were also performed by finite element analyses (FEA) according to the proposed method. The J–R curves obtained for the plate specimens commonly showed similar behaviors of having significantly higher J for the small Δa range from 0 to about 2 mm than that for the compact tension (C(T)) specimen, indicating a difference in the plastic constraint in the crack tip between the two types of specimens. These results demonstrate that the method proposed in this study is highly useful for evaluating the J–Δa relationship of the fracture test specimen. Fracture assessments using the J–R curves of the plate specimens provided a better prediction of the fracture load than that using the J–R curve of the conventional C(T) specimen. All the results supported the applicability of the EPFM methodology in the fracture evaluation, shown in the previous work.
Damage Evaluations for BWR Lower Head in Severe Accident Based on Multi-Physics Simulations
Authors: Katsuyama Jinya , Yamaguchi Yoshihito , Nemoto Yoshiyuki , Furuta Takuya , Kaji Yoshiyuki
Published: November 2022

To assess rupture behavior of the lower head of reactor pressure vessel in boiling-water-type nuclear power plants due to severe accident like Fukushima Daiichi, we have been developing an analysis method based on coupled analysis of three-dimensional multi-physics simulations composed of radiation transport, thermal-hydraulics (TH) and thermal-elastic-plastic-creep analyses. In this simulation, Monte Carlo radiation transport calculation is firstly performed by using PHITS code to compute proton dose distribution considering molten conditions of core materials. Then the deposit energies at each location is imported into TH analysis code ANSYS Fluent with the same geometry and temperature distribution is simulated by thermal-fluid dynamics. Finally, temperature distribution obtained from TH analysis is applied to thermal-elastic-plastic-creep analyses using FINAS-STAR and then damage evaluation is carried out based on several criterions such as Kachanov, Larson-Miller-parameter, melting point. To conduct such analyses, we also have continued to obtain experimental data on creep deformation in high temperature range. In this study, to predict time and location of reactor pressure vessel (RPV) lower head rupture of boiling water reactors (BWRs) considering creep damage mechanisms, we performed creep damage evaluations based on developing analysis method by using detailed three-dimensional model of RPV lower head with control rod guide tubes, stub tubes and welds. From the detailed analysis results, it was concluded that failure regions of BWR lower head are only the control rod guide tubes or stub tubes under simulated conditions.
Environment Assisted Fatigue – Rules, Assumptions and Challenges for Fatigue Management of Primary Piping
Authors: Solin Jussi , Seppänen Tommi , Lemettinen Petri , Vanninen Rami , Pulkkinen Erkki
Published: November 2022

This paper introduces and discusses the commonly used methods for calculating environmental penalty factors (Fen) to be used in fatigue assessment of stainless reactor components.

Three alternative methods for determining Fen factors are introduced and instructed in the JSME S NF1-2009 Code in a language providing a designer the guidance needed for reliable and repeatable EAF assessment. Following these instructions together with the equations and parameters given in the NUREG/CR-6909 it is possible to obtain same Fen factors as by careful reading of the NUREG/CR-6909 alone.

The NUREG/CR-6909, Rev. 1 contains notable amounts of valuable information, but instructions for application can be ambiguous or conflicting. An example related to the modified strain rate approach for determining Fen factors is provided.
Research and Development of Viscous Fluid Dampers for Improvement of Seismic Resistance of Thermal Power Plants: Part 12 Vibration Measurement of Existing Boiler Structure
Authors: Minagawa Keisuke , Aida Kiyoshi , Fujita Satoshi
Published: November 2022

Thermal power generation is a very important power source until renewable energy or carbon-free energy become widespread.

Japan is one of the most earthquake-prone countries in the world, and coal-fired power plants have been damaged by major earthquakes. For example, strong earthquakes such as the Great East Japan Earthquake in 2011, the Hokkaido Eastern Iburi Earthquake in 2018 and the earthquake off the coast of Fukushima in 2021 caused coal-fired power plants to shut down for long periods of time, and these had a significant impact on society. Therefore, it is important to improve the seismic safety of existing coal-fired power plants in earthquake-prone countries such as Japan.

The authors have proposed an application of visco-elastic dampers to a boiler structure in a coal-fired power plant to improve seismic performance. In our past papers, development of the damper, manufacturing and various experimental tests of prototypes were carried out, then the application of the damper was effective to reduce the base shear force of a support structure of the boiler, and the dampers had a long lifetime for continuous deformation.

In order to effectively apply these dampers to a boiler structure, it is important to construct an analysis model of the boiler structure for suitable distribution of dampers. Thus observations of actual seismic response of the boiler structure to build an accurate analysis model are required. Therefore, this paper deals with a long-term vibration measurement of seismic response of an actual coal-fired thermal power plant in Japan. The long-term vibration measurement will also effective for early detections of damage due to aging or earthquakes. A system of the vibration measurement and an example of the measurement results will be reported in this paper.
Development of C-Ring Geometry to Explore Fatigue Crack Extension and Verification in High-Pressure Vessels
Authors: Wheeler Robert W. , Ronevich Joseph , San Marchi Chris , Grimmer Peter , Emery John M.
Published: November 2022

High pressure hydrogen storage vessels are frequently retired upon reaching their designed number of pressure cycles, even in cases where the in-use pressure cycles are significantly less severe than the design pressure cycle. One method for extending the life of hydrogen vessels is recertification through non-destructive evaluation (NDE); however, NDE techniques are frequently evaluated with machined defects in test samples rather than fatigue cracks which occur during pressure cycling and may be more difficult to detect. In this paper, 50 mm wide ring sections (called C-rings, since they represent slightly more than half the circumference) were extracted from pressure vessels and mechanically cycled to establish fatigue cracks. Sub-millimeter starter notches were machined, via plunge electrical discharge machining (EDM), to control the location of crack initiation. Crack growth was monitored via direct current potential difference (DCPD) and backface strain gauges, both of which were shown to be good indicators for crack propagation. The C-ring geometry and fatigue crack growth were modeled to demonstrate the ability to monitor/control the crack length and area, which can be used to develop calibration samples of varying crack depth for NDE techniques. Additionally, this sample is intended to evaluate the influence of residual stresses on the sensitivity of NDE techniques, such as the design stresses in autofrettaged vessels.
A Methodology for Calculating the Minimum Pressurization Temperature of New Built Hydroprocessing Reactors in 2¼Cr-1Mo-¼V Low Alloy Steel
Authors: Rensman Jan-Willem , Frittitta Davide , Fusari Fausto , Ronchi Nicola
Published: November 2022

Minimum Pressurization Temperature (MPT) is the lowest temperature at which a hydroprocessing reactor can start pressurizing safely. A reliable MPT evaluation is necessary due to the susceptibility of hydroprocessing reactor materials to the combined effects of temper embrittlement and hydrogen embrittlement. Accurate estimation of the MPT is important for owners, who are looking for the lowest MPT values to reduce start-up time.

Several methods to develop an MPT have been adopted in the past mainly based upon experimental data and/or acquired from material exposed in reactors over time. Most of these methods are based on historical concepts of hydrogen embrittlement in conventional 2¼Cr-1Mo alloys. For 2¼Cr-1Mo-¼V low alloy steels, hydrogen diffusion and trapping capacity are different and thus, potential for internal cracking is different. In addition, experiments to assess the influence of external hydrogen environment on stable cracking have been reported and provide more insight into stable crack growth potential due to a hydrogen atmosphere.

The traditional methods could lead to an overly conservative approach. The result could lead to an over-estimation (i.e., a shift to higher temperature envelope) of the MPT curve.

In this paper the authors describe a methodology for deriving the MPT for new built 2¼Cr-1Mo-¼V low alloy steel reactors. It is based on API TR-934 F parts 3 and 4 [1],[2] combined with some practices from WRC Bulletin 562 [3]. A case study will be described and a comparison with results according to historical calculations will be presented.
A Novel Real-Time Evaluation Method for the Temperature Field in the Electrofusion Welding of Polyethylene Pipe
Authors: Guo Weican , Tao Yangji , Miao Cunjian
Published: November 2022

In the electrofusion (EF) welding process of polyethylene (PE) pipes, the welding temperature field and its variations are available for predicting EF joint properties. The welding temperature field has key factors, which determine the welding quality to influence EF joint properties. However, it is difficult to measure and evaluate the welding temperature field in real time. We proposed a novel real-time evaluation method for the temperature field in the EF welding process of PE pipes. The temperature field in the EF welding process was simulated, based on a one-dimensional unsteady state heat transfer model. In the simulation, the temperature of the fusion zone dropped at the same rate. The EF joints of the whole welding process were detected by the ultrasonic phased array inspection, and phased array images were recorded in real time by using the video recording function of ultrasonic inspection instruments. According to the rate of temperature dropping in the fusion zone, the measurement model of the welding temperature field was established with video recordings. Then, welding temperature fields were evaluated in real time by using the temperature field of the normal welding process. Furthermore, the evaluation method was to set the foundation for exploring the formative mechanism of EF joint strength and optimizing welding parameters.
Artificial Intelligence for the Output Processing of Phased-Array Ultrasonic Test Applied to Materials Defects Detection in the ITER Vacuum Vessel Welding Operations
Authors: Ortiz de Zuniga Maria , Prinja Nawal , Casanova Cristian , Dans Alvarez de Sotomayor Andres , Febvre Max , Camacho Lopez Ana Maria , Rodríguez Prieto Alvaro
Published: November 2022

Artificial Intelligence (AI) has been applied to accelerate the analysis of outputs from the phased-array ultrasonic (PAUT) non-destructive testing (NDT).

The aim of this work is the development and analysis of AI tools for the output processing of PAUT applied to welding defects detection in the ITER Vacuum Vessel manufacturing. The development of the AI model, parameters of the data and data processing are described herein.

This development shows that AI is an appropriate tool to process PAUT data, resulting in an accuracy of prediction of over 83%. This allows for prompter data availability and gives an additional information set in order for projects to take informed decisions. The human error factors are decreased through this automation, as is the large time required to process each PAUT output, which can be decreased from an average of a week to a matter of minutes. A successful AI application for UT has a potential to save time and cost.