bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Simulation of Transitions Between Forced Circulation and Natural Circulation With Nuclear Reactivity Feedback
Authors: Chen Hanying , Xia Linzhong , Gao Puzhen , Tan Sichao , Yuan Hongsheng
Published: October 2021

For a nuclear power reactor operating under forced circulation (FC) and natural circulation (NC) conditions, during transitions between these two types of circulation condition, nuclear reactivity fluctuation will occur due to sudden coolant flowrate change, and the reactivity fluctuation will in turn cause variation of nuclear heating power. In order to provide a more achievable and less costly approach for experimentally investigating transient thermal-hydraulic behavior of these transitions between NC and FC in nuclear power reactors, we designed and established an electrically-heated experimental loop. The established experimental loop has a heating section, whose heating power is controlled in real time and programmed to simulate the nuclear power variation caused by fuel and coolant temperature reactivity feedback. This experimental simulation is specifically implemented by coupling the point kinetics model with temperature measurements of the electrically heated experimental loop. In our study, reactivity feedback during both NC-to-FC transition and the reverse transition were simulated experimentally, and different reactivity compensation strategies were tested. The simulation results show that: in transitions from FC to NC, the decrease of power in initial stage of the transitions can restrain the fast increase of the fuel temperature; while in transitions from NC to FC, enough negative reactivity should be inserted as soon as the circulation pump is shut down, so as to avoid the nuclear power increase peak.
Steam Generator Grade P91 Steel Components Creep-Assessment By Test After Extended Service
Authors: Grisolia Ottaviano , Scano Lorenzo , Piccini Francesco , Lo Conte Antonietta , De Agostinis Massimiliano , Fini Stefano
Published: October 2021

Previous study carried out creep analysis for steam generator high-temperature-section two components, outflow tubing and manifold of the superheater harp: they may have been critical because of the long continued service (109,000 hours or twelve years) and loading conditions, including maximum operation temperature (565°C) and applied stress (65 MPa). Metallographic methods by replica had showed no evidence of the creep cavitation in all the positions considered for both tubing and manifold. In particular, they had not found any cavitation or phases affecting creep strength of the material in the base, HAZ and weld metal microstructure. Now, present study carries out investigation for the two components based on the next plant outage outcome, after further 20,000-hours service. Both metallographic methods and hardness measurements’ results would compare with previous ones providing microstructure evolution in the period.
Development of the Buckling Evaluation Method for Large Scale Vessel by the Testing of Gr. 91 Vessel Subjected to Horizontal and Cyclic Vertical Loading
Authors: Okafuji Takashi , Miura Kazuhiro , Sago Hiromi , Murakami Hisatomo , Ando Masanori , Miyazaki Masashi
Published: October 2021

The current buckling design standard of Class 1 vessels for fast reactors (FRs) power plant in Japan, “Design and Construction for Nuclear Power Plants, Division 2 Fast Reactors” by the Japan Society of Mechanical Engineers, focuses primarily on plastic buckling of austenitic stainless steel vessel. For next-generation FRs, the higher-yield material, especially ASME Grade 91 steel, plans to be applied to the vessels such as steam generators in addition to austenitic stainless steel. Seismic isolation system is also being devised in the next plant to meet the design seismic load in Japan.

To accommodate these conditions, the standard buckling strength equations in Japan were proposed in previous study, which were modified by considering elasto–plastic buckling of vessel. The modified equations consisted of elasto–plastic axial compression, bending, shear buckling, and their interactions, as well as ASME/BPVC CASE N-284, considering the reduction of buckling strength by cyclic larger vertical load with long–period lower horizontal load under the horizontal seismic isolation plant design.

The applicability of the modified buckling equations to high-yield material was confirmed by a series of buckling tests under the monotonic load to Grade 91 steel vessels with an initial imperfection mode in previous study.

In this study, the applicability of the proposed modified buckling equations was confirmed through a series of buckling tests under cyclic loading considering horizontal seismic isolation, or with the circumferential wrinkle shape corresponding to elephant’s foot buckling (EFB) mode as the conservative initial imperfection shape. These tests were simulated by elasto–plastic buckling analyses considering stress–strain relationship and imperfections in the test vessels with high accuracy, and these test and analysis results showed the applicability of the modified equations.

The effect of initial imperfection shape of large vessels manufactured by multiple plates welding on the buckling load was evaluated via a series of analyses. In these analyses, the superimposition of global imperfection shape due to accumulation of misalignment of plates in the buckling mode imperfection, and the local imperfection and residual stress by welding had minimal effect on the buckling load.

These buckling test and analysis results confirmed the contribution of the factors to the buckling strength such as initial imperfection and loading, and showed that the modified equations are applicable to the vessels in FRs power plant.
Sensitivity Analysis of Tunable Equation of State Material Model In Pulsed Mercury Target Simulation
Authors: Lin Lianshan , Winder Drew
Published: October 2021

A pulsed neutron spallation target is subjected to very short but intense loads from repeated proton pulses. Approximately 60% of the energy from each proton pulse is deposited into the mercury target material and the stainless-steel target structure, leading to a high-pressure region in both the stationary target structure and the flowing mercury. The high-pressure region propagates and leads to fluid-structure interaction. The resultant loading on the target structure containing liquid mercury is difficult to predict, although various simulation approaches and material models for the mercury have been tried. To date, the best match of simulation to experimental data is obtained by using an equation of state (EOS) material model with a specified tensile cutoff pressure, which simulates the cavitation threshold. The inclusion of a threshold to represent cavitation is key to the successful predictions of stress waves triggered by the high-energy pulse striking the mercury and vessel. However, recent measurements of target structure strain show that significant discrepancies remain between the measured and simulated strain values in the EOS mercury model. These differences grow when noncondensable helium gas is intentionally injected into the flowing mercury to reduce the loading on the structure. An EOS-based proportional–integral–derivative (PID) mercury model has been proposed to reduce the gap between the measured and simulated vessel strain responses for targets with gas injection. The conceptual and numerical description and initial investigation of the PID model are presented in previous work. Further studies of this PID model — including the sensitivity of the structure’s strain response to model parameters (the tensile cutoff, PID parameters Kp, Ki, and Kd) — are reported in this article. Results show the strain response is more sensitive to changes in the tensile cutoff value than to changes in the model parameters Kp, Ki, and Kd. These results will aid in future work where the model parameters will be optimized to match simulation data to strain measurements.
Seismic Fragility and Behavior of Spherical Pressure Vessels
Authors: Öztürk Sezer , Akgül Kayahan , Sarı Ali
Published: October 2021

Pressurized tanks are vessels that show high impermeability and strength against large internal pressures. These tanks can be used for liquid or gas storage. The internal pressures of the vessels used in gas storage can be at very high levels. These tanks are used in many different areas in the industry. Therefore, human health and life safety is an important parameter. Thus, the design of the tanks to be produced must be suitable for the purpose, as well as the correct analysis and safe usage conditions. Excessive pressure and the temperature difference can lead to explosions that will cause dangerous and many fatal accidents. As a result, domino effects can occur in industrial facilities. For this reason, the risk analysis and seismic behavior of these vessels should be carefully examined. When the performances of past earthquakes are examined, it has been revealed that especially spherical vessels show seismic fragility. Therefore, evaluating the seismic fragility of these vessels is an important issue in regions with high seismic risk. Fragility curves are important tools to evaluate the vulnerability of structures to earthquakes. Within the scope of this study, fragility curves have been created by considering nonlinear time history analyzes and the limited database analyzed for the damage conditions of spherical pressure vessels in earthquakes that occurred in the past years. The curves obtained were interpreted in relation to the ground motion intensity parameter (PGA). In addition, nonlinear time history analyzes of tank models using the Finite Element Method (FEM) have been performed to evaluate the seismic performance of the vessels. Also, the damage data of horizontal tanks were collected and interpreted.
Strain Based Damage Model Predictions of Ductile Crack Growth in Multiple Fracture Specimen Geometries
Authors: Kalyanam S. , Hill L. T. , Wilkowski G. , Hioe Y. , Brust F. W.
Published: October 2021

Modeling damage and ductile crack growth in metallic materials has been of interest over the last four decades. Damage models of increasing complexity have been employed to characterize and predict the ductile crack growth in materials. A short review of the existing ductile crack growth models has been provided. Recently, a strain-based damage model has been advanced by researchers, which is capable of capturing the stress and strain states for the incipient damage within the material while being able to capture the triaxiality parameter. In this work a strain based ductile fracture damage model has been employed to model specimens with three different crack geometries, namely a single-edge notch tension SEN(T), compact-tension C(T), and outer diameter (OD) axial surface-cracked pipe. The predictions from the ductile crack growth model have been compared to experimental findings of the crack growth (obtained using a d-c Electric Potential measurement technique) and the corresponding load levels and crack opening displacements (CODs). The points of similarity between the experimental measurements and the fracture surface observations of crack growth and the predictions from the finite element modeling (FEM) approach have been discussed. The same X80 material properties and damage model parameters were employed to benchmark the ductile crack growth in two different SEN(T) specimens with differing normalized crack depths (crack/width ratios, a/W), a C(T) specimen (a/W = 0.5), and an OD SC pipe (a/t = 0.6) to shed light on the predictability of the crack initiation event and the subsequent ductile crack growth until failure. The findings provide credence to the applicability of the new approach for piping materials while providing a framework for flaw evaluation methodologies. The investigation also opens the doors for regions where mesh regularization methods and modeling approaches along with mathematical relations can be developed to form a more efficient framework for modeling specimens with diverse constraints efficiently.
Research and Development of Viscous Fluid Dampers for Improvement of Seismic Resistance of Thermal Power Plants: Part 11 Optimization of Dampers by Genetic Algorithm
Authors: Minagawa Keisuke , Aida Kiyoshi , Fujita Satoshi
Published: October 2021

In Japan, thermal power generation is one of the important power sources after the Great East Japan Earthquake in 2011. On the other hand, some thermal power plants were damaged by the Great East Japan Earthquake or Hokkaido Eastern Iburi Earthquake in 2018, therefore strengthening of seismic performance of thermal power plants has been required for reliable power supply against large earthquakes that will occur in the future. The authors have proposed an application of visco-elastic dampers to a boiler structure in a coal-fired power plant to improve seismic performance. The application of dampers 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 our past papers, the parameters were selected manually. However, to design proper parameters and distribution of the dampers on manual is laborious works with many seismic response analyses. Therefore, the genetic algorithm was introduced to the parameter selection of dampers in this paper. The genetic algorithm is one of the optimization algorithms that was inspired by the evolution process of creatures. The genetic algorithm creates a virtual population having genes in the computer, and only individuals with high fitness remain while repeating generational changes. In this paper, parameters of dampers that can reduce the base shear force were searched by the genetic algorithm. This approach can be applied to vibration controls for other industrial facilities.
Fatigue Life Calculation Method of 4130X High Pressure Hydrogen Storage Cylinder With Initial Crack Defect
Authors: Ge Peng , Chen Zhiping , Liu Mengjie
Published: October 2021

Hydrogen storage cylinders are often used for medium- and short-distance transportation of hydrogen. The presence of hydrogen tends to increase the risk of using the gas cylinders. The alternating stress caused by factors such as hydrogen charging and discharging during the service process of the gas cylinder leads to the expansion of initial cracks inside the cylinder and the final fatigue fracture. At present, the fatigue life calculation of pressure vessels mainly adopts the S-N curve method, however, some steels do not have the S-N curve under the hydrogen environment, it is necessary to use fracture mechanics methods to analyze the fatigue life of gas cylinders in a high-pressure gaseous hydrogen environment. In this work, a method for calculating the fatigue life of fracture mechanics for hydrogen storage cylinders was established according to ASME VIII-3 KD-10. The development of the program was completed by Matlab. An example was given to illustrate the program. Firstly, basic parameters of the material used for the cylinder were obtained. Then, finite element method was used for stress analysis to obtain the fitting curve and the function expression of hoop stress. Finally, fatigue life calculations of high pressure hydrogen storage cylinder were made. The minimum service life of example was predicted to be 40 years. This result is consistent with the good service history of this type of container. This work could contribute to design, safety evaluation of hydrogen storage cylinders.
Design of Piping Systems for Accidental Explosion and Fire Events
Authors: Akinci Necip Onder , Loudoun James , Parvathaneni Krishna , Kim Hyun-Su
Published: October 2021

Piping systems constitute the most critical portion of process plants. Proper blast and fire design of critical piping systems improve safety and resiliency. Design of piping and pipe supports are typically governed by operating and abnormal load conditions depending on the design basis. Well established analysis and design methodologies as per the applicable ASME codes ensure performance of piping systems against load cases such as internal pressure, thermal expansion, self-weight, wind, seismic and vibration. Pipe stress analysis using code based linear elastic analysis methods allow design for these types of conventional load cases in a practical way. However, beyond design basis load cases from hydrocarbon accidents including explosion and fires can pose additional challenges. Limitations of conventional design tools against demands due to extreme events require use of more advanced techniques. This study presents a practical approach for assessment and design of piping systems for hydrocarbon accident events. Performance based failure criteria for piping systems has been shown to reduce the conservatism compared to allowable stress design for extreme events. Examples from major projects and case studies are also presented to demonstrate the technical approach. Consideration of a holistic approach accounting for interaction of piping and its support structure plays a key role in improving the design process.
Numerical Studies on Modal Analysis of Curved Tube and Coil Tube in Coil-Wound Heat Exchanger
Authors: Wang Yue , Ren Peng , Zhu Guorui , Tan Wei
Published: October 2021

Coil-wound heat exchanger, which has a large-scale turbulence in the shell side and a great heat transfer coefficient, has been widely used in chemical industry, such as liquefied natural gas (LNG) and crude pyrolysis of ethylbenzene. To investigate the general vibration characteristics, a complete wound tube can be divided into the curved tube and the coil tube for easy research because of its constraint condition. A finite element analysis is used to obtain the natural frequencies and corresponding mode shapes of the curved tubes and the coil tubes with various parameters. For the curved tube, the deformation of middle position of the tube is larger than that of the clamped ends. The maximum deformation occurs at the transition from the bending tube to the straight tube. With the increase of R1 and the decrease of R2, H1, H and θ, the natural frequencies of curved tube increase which is more likely to avoid the fluid-elastic instability, in which R1 is circumferential radius of the straight part of curved tube, R2 is coil radius, H1 is axial straight tube length, H is axial height of curved tube and θ is deflection angle. And for the coil tube, all the deformation for mode shape occurs in the axial direction, and there is no obvious deformation in the radial direction. With the increase of support number and the decrease of R2, the basic frequency of the coil tube increases. It provides a certain reference for the support layout of coil-wound heat exchanger.
Benchmark Analysis by Beremin Model and GTN Model in CAF Subcommittee
Authors: Hirota Takatoshi , Nagoshi Yasuto , Hojo Kiminobu , Okada Hiroshi , Takahashi Akiyuki , Katsuyama Jinya , Ueda Takashi , Ogawa Takuya , Yashirodai Kenji , Ohata Mitsuru , Minami Fumiyoshi
Published: October 2021

In order to establish a guideline for fracture evaluation without excessive conservatism by considering plastic constraint in the ductile-brittle transition temperature (DBTT) region, the CAF (Constraint-Based Assessment of Fracture in Ductile-Brittle Transition Temperature Region) subcommittee has been launched in 2018 in the Atomic Energy Research Committee of the Japan Welding Engineering Society with a five years’ term. In the committee, fracture tests are conducted using laboratory specimens of C(T), SE(B), and 50mm-thick flat plate with a surface flaw subjected to bending load or tensile load to verify fracture evaluation methods, which strongly depend on numerical simulation. Since simulation results are easily affected by analysis conditions, benchmark analysis is essential for the potential users of the guideline. Therefore, benchmark analyses are executed on brittle and ductile damages by Beremin and Gurson–Tvergaard–Needleman (GTN) models implemented in the FE codes owned by the committee members. The benchmark analyses are carried out in four steps; Step 0 is to confirm the output of finite element (FE) codes in each member with the same input data and the same FE model. Step 1 is to confirm the result of Weibull stress analysis for C(T) specimens tested at −125°C. The Weibull parameter, m, was fixed in this step. At step 2, sensitivity analyses are conducted on Weibull stresses in different conditions. The outputs by the GTN model are also confirmed. At the final step, the fracture simulation will be run for flat plate specimens with less plastic constraint than the standard fracture toughness specimen. As the results of the benchmark analyses up to step 2, a significant difference are not observed in the Weibull stress computed by committee members with the same input data and FE model and it is confirmed that the effects of element type, nonlinear deformation theory employed in FE analysis and convergence procedure for the Weibull parameter m are marginal by the sensitivity analyses. For the calculation of the Weibull parameter m by using the fracture toughness test results and the developed programs by committee members, the converged values of m show good agreement among them. The obtained knowledge by the benchmark analyses is used to establish the guideline for fracture assessment of structural components with different plastic constraints.
Testing a Tunable Diode Laser Absorption Spectroscopy Oxygen Analyzer
Authors: Reich Alton , Shaw James , Bergmans John
Published: October 2021

Chemical processing systems can be controlled using a wide variety of instrumentation. Often pressure and temperature are key parameters that are monitored and controlled, and this instrumentation is extremely mature technology. In some cases, chemical concentrations are a key process parameter that must be monitored and used as an input to the system controller. Chemical concentrations may be monitored indirectly through pH or conductivity. Direct measurements are often made via electrochemical cells, but these tend to have slow response times.

For chemical processes that operate in batch mode, particularly ones that have relatively short cycle times, chemical sensors that have fast response and recovery times are needed, and electrochemical sensors may not be suitable. This paper describes such an application where the chemical concentration of oxygen is an important process and safety parameter. A Tunable Diode Laser Absorption Spectroscopy (TDLAS) oxygen sensor was selected for this application because of the short response and recovery time. When the oxygen sensor was received, it was set up in the laboratory and tested to verify measurement accuracy and data communication with the sensor. During this testing, we discovered that the sensor produced incorrect output over a portion of the system operating pressure range. The root cause of the error was traced to how the firmware (sensor operating software) handled the measured pressure input to produce the oxygen concentration output. The paper discusses the laboratory testing setup, and the testing that was executed. A structured test program was executed that enabled us to understand the nature of the incorrect measurement, and trace the source of the error to the sensor operating software.
Seismic Analysis of VVER-1000 Polar Crane
Authors: Dubyk Yaroslav , Antonchenko Vitalii
Published: October 2021

This article discuss an analytical dynamic model of a polar crane to assess its seismic strength based on artificially generated accelerograms. The polar crane is installed under the dome of the VVER-1000 NPP containment and serves to move various cargoes in the reactor compartment, including nuclear hazardous cargo. The high-rise location of the crane (+ 55m) causes the possibility of significant seismic loads. To build a dynamic model, at the beginning, the stiffness of individual elements was analyzed using numerical and analytical methods. In particular, the stiffnesses of the main beams and the main balancers are analyzed to determine the type of dynamic model required. A feature of the seismic analysis of a polar crane is the nonlinear interaction of its elements, which can lead to the breaking of some connections and the separation of the structure from the supporting elements. The key in the analysis is taking into account the contact nonlinearity of the wheel-rail pair; to model this contact, we used the classical theory of Hertz. The generalized response spectra for the NPP site were used as the load. A method for calculating artificial accelerograms, which are generated for the purposes of dynamic analysis, based on response spectra is used. Also, as a comparison, the results of calculating the seismic strength of the polar crane by the linear response spectrum method are given. As a result of the analysis, weak points in the structure were identified, and the ultimate seismic resistance of the polar crane was determined.
Stress Analysis of Tubes During Die Expansion Process
Authors: Zhao Zijian , Bouzid Abdel-Hakim
Published: October 2021

In practical applications, the stress status of expanded tubes is a critical parameter to control leakage and stress corrosion cracking. Therefore, it is important to study and analyze the stress distribution generated from tube expansion. Unfortunately, there are only a few theoretical approaches available for estimating the stress distribution of formed tubes, especially for cases where the expansion is achieved with spherical and oval dies.

In this study, 3/8 stainless steel and copper tubes were expanded with an oval die in a designed test workbench, and the tangential and longitudinal strains were monitored during the expansion process. A new analytical approach is developed to estimate the stresses and strains in the expanded tube during the expansion process. The different expanded zones are treated using different theories. An axisymmetric finite element model as a numerical approach is used to analyze the stresses based on a multi-linear kinematic hardening behavior to validate the analytical approach.

In addition, the stresses in the expanded tube and the push force of the die are also provided by the analytical, numerical and experimental approaches. Finally, the results from the three approaches are in a relatively good agreement.
INCEFA-SCALE (Increasing Safety in NPPs by Covering Gaps in Environmental Fatigue Assessment - Focusing on Gaps Between Laboratory Data and Component-Scale)
Authors: Mottershead Kevin , Cicero Roman , McLennan Alec , Courtin Stephan , Huotilainen Caitlin , Cicero Sergio
Published: October 2021

INCEFA-SCALE is a five year project supported by the European Commission HORIZON2020 programme. It is the successor to the INCEFA-PLUS programme that ran from 2015 to 2020. INCEFA-SCALE kicked off in October 2020. The objective is to continue work, advancing the ability to predict lifetimes of Nuclear Plant components when subjected to Environmental Assisted Fatigue loading (EAF).

It has been generally observed by nuclear plant operators that the number of failure events attributable to EAF is fewer than predicted by the current assessment methodologies. It is internationally recognised that a possible contributor to this discrepancy is the transferability of laboratory-scale tests to real nuclear components. EPRI, in the USA, is leading a series of component-scale environmental fatigue tests that are expected to advance data availability significantly; however, the ability to address transferability of laboratory-scale tests to real component geometries and loadings will still be constrained by limited test data. This is the knowledge gap addressed by INCEFA-SCALE. The project strategy will be (1) the development of comprehensive mechanistic understanding developed through detailed examination of test specimens and MatDB data mining, and (2) testing focussed on particular aspects of component-scale cyclic loading. The project will initially survey and understand the vast amount of test data within JRC’s MatDB database (from the predecessor INCEFA-PLUS project, and from other external sources such as USNRC, EPRI, MHI and the AdFaM project). The experimental programme will be specified in the first year and run for three years. Finally, the project will deliver guidance on the use of laboratory-scale data for component-scale applications.

This paper will report progress in agreeing data gaps, mechanistic understanding needs, and testing requirements.
Hydrogen Induced Cracking Damage Estimation and Evaluation
Authors: Subramanian Kannan , Penso Jorge
Published: October 2021

New non-destructive testing (NDT) inspection technology, quantification of damage, and tensile testing, has enabled the assessment of conservatism associated with the hydrogen induced cracking (HIC) damage parameter (DH) currently used in API 579 – 1/ASME Fitness-For-Service (FFS) Part 7. To address HIC damage from an FFS perspective, the general requirements include addressing protection against plastic collapse and protection against cracking. The focus of this body of work is only to address conservatism regarding the protections against plastic collapse. The detrimental effects of HIC damage on plastic collapse is modeled through the DH parameter, currently set at 0.8 or an 80% strength loss in HIC damage material for the Level 2 HIC Assessment Procedure. Original development of the DH parameter was based on tensile testing of HIC damaged material performed in air, where the HIC damage was not sized or quantified, and a 30% margin was added to the maximum measured reduction in tensile strength to get to the 80% strength loss. Modification of the DH parameter is allowed in the Level 3 HIC Assessment Procedure, provided supporting testing data justifying a reduction is also provided with the assessment.

For the tensile testing in air, the quantified HIC damage and tensile testing results are consistent with an 80% strength loss, without an added margin. A rigorous ultrasonic testing inspection using conventional phased array ultrasonic testing (PAUT) and PAUT with full matrix capture using the total focusing method (FMC/TFM) was performed on ex-service SA-212 Grade B material. Locations with service generated HIC damage were extracted and tensile tested in air and in gaseous hydrogen. Examination of the tensile specimen fracture surfaces allowed for quantification of HIC damage associated with final tensile failure. HIC damage measured with NDT was similar to the HIC damage on the fracture surface when characterized using the crack sensitivity ratio (CSR). The hydrogen tensile testing results suggested that for material still charged with hydrogen (not currently explicitly addressed in API 579 – 1/ASME FFS Part 7), the loss in strength may be larger than 80%.
Micro Ultrasonic Knurling Technology Creating High Precision Texture on Sliding Surface in Mechanical System (Fundamental Experiment)
Authors: Aoki Shigeru , Sakai Yasunori , Tanaka Tomohisa
Published: October 2021

Sliding surface in mechanical system is required to move smoothly and stop at target position. Sliding surface can move and stop by applying adequate friction force. It is necessary to develop machining technology to create texture with high precision and efficiency. On the other hand, ultrasonic vibration is used in many manufacturing fields. It is well known that surface roughness is improved and stress is reduced using ultrasonic vibration. In this study, machining technology creating wear resistant texture on large area sliding surface with high precision and efficiency using ultrasonic vibration during knurling is developed. The technology can be applied to the dampers and the base isolation systems for reduction of seismic response of the structures in this paper, the effect of ultrasonic vibration is examined by the fundamental experiment. In some of those devices, friction characteristics are an important factor for controlling their efficiency. In the experiment making a groove on the surface with an indenter using a 2 dimensional table, pressing force and friction force are measured. These forces are reduced using ultrasonic vibration. Pressing experiment making texture on the surface is also made. Deeper and clearer marks are formed using ultrasonic vibration during knurling.
Investigation on Leak Rates in Thin-Walled Structures
Authors: Silber Fabian E. , Stumpfrock Ludwig , Weihe Stefan
Published: October 2021

The results presented here are an experimental investigation of single phase and two-phase flow of water through pin holes and defined slits. The project was performed to extend the database of experimentally determined leak rates at thin-walled components. Test specimens described herein include five pin holes and three different geometries with defined slits and were manufactured with a wall thickness t of approximately 1.2 mm. Leak rate measurement was performed in parameter range with temperatures ranging from 20 °C to 230 °C and a pressure range from 5 to 75 bar. These experiments cover a t/dh ratio range from 1.4 to 12. Furthermore, leak rates with discharge into a water vessel are compared to free discharge into air environment or rather approximately free discharge into a condenser. As a part of these investigations the formation of a metastable fluid phase in the flow regime at the outlet of the apertures was documented with a high-speed camera, evaluated and categorized for different geometries. Within this contribution an overview of the test facility, the testing procedure, and a selection of results of the investigations will be presented and discussed.
Fatigue Behavior and Lifetime Assessment of the Austenitic Stainless Steel AISI 347 and its Associated Filler Metal ER 347 Under Low-, High- and Very High Cycle Fatigue Loadings
Authors: Schopf T. , Weihe S. , Daniel T. , Smaga M. , Beck T. , Rudolph J.
Published: October 2021

The fatigue assessment of safety relevant components is of importance for ageing management with regard to safety and reliability. Those components are subjected to low cycle (LCF), high cycle (HCF), very high cycle fatigue (VHCF) and their combination in terms of complex loading collectives and nonlinear fatigue damage accumulation. Reactor internals, for example, are subjected to thermo-mechanical fatigue induced by operational temperature transients such as stratification loads and to flow induced vibrations. Obviously, methodological gaps within the current fatigue assessment approach, i.e. the assessment of the VHCF behavior, the treatment of the fatigue damage accumulation in combination with the transient endurance limit are to be bridged. Additionally, environmentally assisted fatigue is to be considered properly.

Design fatigue curves in international design codes were extended from originally 106 up to 1011 load cycles. Nevertheless, the existing data base for load cycles above ≈ 107 is still insufficient. The cyclic deformation behavior of the material under discussion (AISI 347 within the recent project and AISI 304 within a follow-up project) is different depending on the fatigue regime respectively to the applied load or deformation amplitude. While the LCF behavior is already well investigated and the basic behavior in the HCF regime is fairly well known the VHCF cyclic deformation behavior has not been characterized so far. As a consequence, the real damage accumulation of variable amplitude combinations consisting of LCF- and HCF/VHCF loads is still widely unknown.

A cooperative R&D project of MPA Stuttgart, WKK University of Kaiserslautern and Framatome GmbH addresses the existing gaps of knowledge discussed above and has recently been finished.

The following topics will be discussed in detail in the paper:

• Basic characterization of the HCF and VHCF behavior at relevant operational temperatures in air at 106 – 2·109 load cycles (base material and welded material)

• Fatigue behavior at variable amplitude loading (combination of LCF / HCF and LCF / VHCF)

• Numerical simulations and fatigue assessment of VHCF-regime loadings

• Development of a fatigue assessment methodology under consideration of the transient endurance limit and damage accumulation effects including assessment and adaptation of appropriate fatigue damage parameters
Demonstration of Intelligent Welding Machine for Polyethylene Pipe
Authors: Xiang Guangte , Hu Yurui , Zeng Sheng , Shi Jianfeng , Zheng Jinyang
Published: October 2021

Electrofusion (EF) welding is one of the most common connection methods for polyethylene (PE) pipe, as well as thermoplastic pipe and reinforced composite pipe. Conventional EF welding generally adopts constant-voltage welding mode. The welding machine outputs a constant welding voltage to heat the resistance wire within specific welding time. In our previous study, intelligent welding machine was designed to ensure the quality of the EF joint, based on the study of the temperature field in EF joint. In this paper, three experiments were used to show the difference between the intelligent welding machine and traditional welding machine. The intelligent welding machine can actively adjust the welding parameters to ensure the quality of EF joint even it was given the wrong welding voltage and welding time. Compared with the traditional welding machine, the intelligent welding machine can automatically control the maximum temperature and the depth of melting region in EF joint during the welding process, and this method applies for EF joints with various diameters or design welding parameters.
Correlating Incident Heat Flux and Source Temperature to Meet ASTM E1529 Requirements for RAM Packaging Components Thermal Testing
Authors: Baird Austin R. , Gill Walt , Mendoza Hector , Figueroa Victor
Published: October 2021

Often in fire resistance testing of packaging vessels and other components, both the heat source temperature and the incident heat flux on a test specimen need to be measured and correlated. Standards such as ASTM E1529 require a specified temperature range from the heat source and a specified heatflux on the surface of the test specimen. There are other standards that have similar requirements. The geometry of the test environment and specimen may make heat flux measurements using traditional instruments (directional flame thermometers (DFTs) and water-cooled radiometers) difficult to implement. Orientation of the test specimen with respect to the thermal environment is also important to ensure that the heat flux on the surface of the test specimen is properly measured. Other important factors in the flux measurement include the thermal mass and surface emissivity of the test specimen. This paper describes the development of a cylindrical calorimeter using water-cooled wide-angle Schmidt-Bolter gauges to measure the incident heat flux for a vessel exposed to a radiant heat source. The calorimeter is designed to be modular to be modular with multiple configurations while meeting emissivity and thermal mass requirements via a variable thermal mass. The results of the incident heat flux and source temperature along with effective/apparent emissivity calculations are discussed.
Case Study of Supplemental Steel Structures
Authors: Wiseman Phillip , Subedi Raju
Published: October 2021

Supplementary steel provides essential connections between building steel or ground to pipe supports and component supports of power and processing plants. This type of structure is usually with steel members less than 10 feet in length and sustains temperature within the range of the ambient conditions and the pipe or component. Being a connection, the standards and Codes provide an array of stress and geometrical checks that share that of a building and of a pressure boundary. Therefore, the applied engineering mechanics utilized in the analysis of supplemental steel configurations, including but not limited to beams, columns, and frames along with their welded or bolted connections, stretches across multiple engineering disciplines. A study of load cases and load case combinations is performed across multiple configurations of assemblies with industry assumptions incorporated. With the mitigation of sag of pipe systems, study of analytical stress and geometrical checks are evaluated to find any correlations of governing criteria. Additionally, the utilization of two types of structural steel design fundamentals and provisions, Allowable Strength Design (ASD) and Load and Resistance Factor Design (LRFD), are investigated with supplemental steel structures which stem from design considerations of steel buildings. This case study in the analysis of supplemental steel structures provides segue to highlighting how Codes and Standards utilized within the field that overlap other fields.
A Comprehensive Review on Failure Analysis of Electrofusion Joint For Plastic Pipes
Authors: Ge Zhoutian , Yao Riwu , Shi Jianfeng , Zheng Jinyang
Published: October 2021

Electrofusion joint plays an important role in connecting plastic pipes and composite pipes. The safety of electrofusion joint has been of major concern affecting the pipeline system. Existing researches reveal that the failure of electrofusion joints is influenced by intrinsic factors such as welding and installation qualities, and external factors such as various load conditions. The combination of these factors would result in different failure modes of electrofusion joints. This paper provided a comprehensive review of current publications on failure analysis of electrofusion joints focusing on both the intrinsic and external factors. The former summarized premature failure of joints caused by incorrect production procedure before service, while the latter addressed the relation between failure modes and load conditions. Key factors affecting the failure modes were subsequently listed. Ultimately, based on current researches and industry hotspots, prospects on the development of electrofusion joint were discussed.
Fire-Induced Pressure Response and Failure of 3013 Containers
Authors: Mendoza Hector , Gill Walter , Baird Austin , Figueroa Victor G. , Hensel Steve , Sanborn Scott
Published: October 2021

Several Department of Energy (DOE) facilities have nuclear or hazardous materials stored in robust, welded, stainless-steel containers with undetermined fire-induced pressure response behaviors. Lack of test data related to fire exposure requires conservative safety analysis assumptions for container response at these facilities. This conservatism can in turn result in the implementation of challenging operational restrictions with costly nuclear safety controls. To help address this issue for sites that store DOE 3013 stainless-steel containers, a series of five tests were undertaken at Sandia National Laboratories. The goal of this test series was to obtain the response behavior for various configurations of the DOE 3013 containers when exposed to various fire conditions. Key parameters measured in the test series included identification of failure-specific characteristics such as pressure, temperature, and leak/burst failure type. This paper describes the development and execution of the test series performed to identify these failure-specific characteristics. Work completed to define the test configurations, payload compositions, thermal insults, and experimental setups are discussed. Test results are presented along with corresponding discussions for each test.
Regulatory Testing and Posttest Analysis of the DPP-3 Type B Shipping Container for NCT and HAC Tests
Authors: Martinez Oscar , Adeniyi Abiodun , Nogradi Paul , Loftin Bradley , Martinez Coleen E. , Van Hoy Blake
Published: October 2021

Safe transportation of radioactive material using appropriately designed, certified packages ensures protection of the public and environment using rigorous system packaging requirements. This protocol was conducted to determine the effects of drop testing on a Type B shipping package (DPP-3) performance per normal and hypothetical accident conditions tests. Preparation, testing, and post-test evaluations of a Type B shipping package tested to 10 Code of Federal Regulations (CFR) 71.71 and 71.73 requirements are presented. Six packages were subjected to free drop, puncture, and thermal tests per 10 CFR 71.73. The posttest helium leak test showed a leak rate < 1 × 10−7 He-cc/sec, indicating that the containment boundary and leak-tight environment were maintained. Statistical analyses were performed to determine changes in package performance. The null hypothesis was that measurements would not change enough from pre- to post-testing to show statistical significance, which would indicate too much variability in package design. A repeated measures t-test was used to analyze drum lid and containment vessel (CV) torques. All six CV lid torques were statistically significant, but only three drum lid torques were statistically significant. Therefore, lid design caused more variability than necessary when subjected to the horizontal-and-cold, vertical-lid-down, and corner-with-lid-up drop tests. A one-way analysis of variance (ANOVA) analyzed package heights and diameters, with results on height indicating four of the six certification test units (CTUs) were statistically significant. Thus, CTU design caused more variability than necessary when subjected to horizontal-hot, horizontal-cold, corner-lid-up, and corner-lid-down tests. One-way ANOVA analysis of diameter indicated that all six CTUs were statistically significant. Thus, CTU design caused more variability than necessary when subjected to all tests. The DPP-3 has been shown to be an acceptable design for transport of radioactive materials, but statistical analysis revealed that package and test design can be improved to reduce variability in performance before and after testing.
A Case Study of a Challenging Coke Drum Skirt Repair: A Through Wall Crack Extended 360 Degrees Around Circumference
Authors: Gao Huidong , Penso Jorge , Dewees David , Chatham Everett
Published: October 2021

An unusual finding of a through wall crack was discovered along the skirt to bottom head weldment. The crack extended nearly 360-degrees along the circumferential weld seam. This flaw resulted in the drum level dropping approximately 2.5 inches onto the skirt resulting in a visible lean of the drum relative to the adjoining support structure.

This paper describes the inspection, engineering analysis, and repair performed after discovery of this challenging situation. Initial inspection included quantitative measurement of the drum displacement and skirt cracking. Engineering analyses included stability analysis of the coke drum, development of a robust and technical viable repair plan, design of a lifting & rigging system to enable repair in the field, controlled deposition welding (CDW) approach, and detailed description of non-destructive examination (NDE) techniques to assure repair quality control. A skirt crack monitoring program and operation cycle optimization were also implemented following the successful repair of the severe cracking along the drum skirt.