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ASME Pressure Vessels and Piping Conference (PVP)

作者： Prewitt, T. J. Bednorz, Michael DNV Dublin OH 43017 USA

ISBN: (纸本)9780791886151

Intermittent pipe movement due to transient pressure events including vapor column collapse or water hammer events can impart large strains into the pipe, cause damage to the support structure, damage coatings, and cause damage or failure of the pipe. This paper will present a method that has been used with success for determining the pipe stresses and strains and possible cause associated with a transient pressure event based on coating damage evidence gathered from in-field assessments. After constructing a hydraulic model of the piping system, various transient events were modelled to obtain resulting pressure over the transient event's period at key points along the piping system, such as valves and elbows. A second, more refined finite element model was created to incorporate the pressure values to determine the resulting displacements and stresses to relate to the in-field measurements of the region in question. By comparing the displacements in the model to the field evidence, the models were calibrated, and evaluation of the likely cause of coating damage found in the field was able to be performed. Moreover, the stresses in the pipe during the event are able to be assessed which allows for damage assessments to be conducted and allows for corrective actions to take place. Transient events assessed ranged from valve openings and closures, pump start up, and vapor column collapse.

关键词： Dynamic analysis finite and boundary element methods

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AN ESTIMATE OF SPENT NUCLEAR FUEL MECHANICAL LOADS IN THE GENERAL 30 CM PACKAGE DROP SCENARIO

AN ESTIMATE OF SPENT NUCLEAR FUEL MECHANICAL LOADS IN THE GE...

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ASME Pressure Vessels and Piping Conference (PVP)

作者： Klymyshyn, Nicholas Kadooka, Kevin Spitz, Casey Fitzpatrick, James Pacific Northwest Natl Lab Richland WA 99354 USA

ISBN: (纸本)9780791886199

The US Department of Energy Spent Fuel and Waste Science and Technology (SFWST) program is performing research to determine the mechanical loading conditions applied to spent nuclear fuel (SNF) during normal conditions of transport to inform mechanical tests of SNF and close an important knowledge gap related to the practical disposition of SNF in the US. Researchers at Pacific Northwest National Laboratory (PNNL) have completed an extensive finite element study to characterize and estimate the potential mechanical loads on SNF during a hypothetical 30 cm drop of an SNF transportation package. This modeling study is validated with test data collected by the SFWST program during a physical test campaign that included one-third scale package drop tests and full-scale single fuel assembly drop tests. The test campaign was led by Sandia National Laboratories (SNL) and included international collaboration with Equipos Nucleares S.A, S.M.E (ENSA) and Bundesanstalt fur Materialforschung und -prufung (BAM). The key contribution of the modeling study is to go beyond the limitations of the limited number of physical tests to estimate the impact response to variations in impact angle, initial gap conditions, fuel assembly design, burnup and other parameters that affect the mechanical loads. The methodology of this study included a classic parametric study to calculate the impact response of highly detailed fuel assemblies over many combinations of parameters. Models of a 17x17 pressurized water reactor fuel assembly and a generic 10x10 boiling water reactor fuel assembly were both used in this study to cover the major fuel assembly types in the US inventory. Over 2,000 impact responses were calculated. The results of the parametric study were evaluated using traditional methods and basic statistics. The results were also used to construct a damage model using multiple nonlinear regression techniques to predict the mechanical loads over the full range of all input parameters. T

关键词： Dynamic Analysis finite and boundary element methods Numerical and Computational Reactor/Nuclear Structural Integrity

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LARGE-SCALE PARAMETRIC MODELING OF SPENT NUCLEAR FUEL DYNAMICS IN THE 30 CM PACKAGE DROP SCENARIO

LARGE-SCALE PARAMETRIC MODELING OF SPENT NUCLEAR FUEL DYNAMI...

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ASME Pressure Vessels and Piping Conference (PVP)

作者： Kadooka, Kevin Fitzpatrick, James Klymyshyn, Nicholas Pacific Northwest Natl Lab Richland WA 99354 USA

ISBN: (纸本)9780791886199

Packages used to transport spent nuclear fuel (SNF) are required by the U.S. Code of Federal Regulations 10 CFR 71.71 to demonstrate satisfactory performance during a drop scenario. While the CFR is meant to ensure safe package function, it does not evaluate survival of the SNF within. The U.S. Department of Energy Spent Fuel and Waste Science and Technology program is working on closing the knowledge gap related to the response of SNF to external mechanical loads, including the 30 cm package drop scenario in the CFR. In support of this effort, LSDYNA finite element simulations were developed by Pacific Northwest National Laboratory (PNNL) to model generic drop scenarios at both the package and fuel assembly level. The models were validated against one-third scale package and full scale fuel assembly drop test data and were exercised to predict fuel cladding strains in a narrow range of model configurations. This work describes a large-scale parametric study conducted by PNNL using the previously developed and validated PWR finite element model, with the addition of a new generic BWR assembly model. The motivation for the parametric study was to characterize the broad range of SNF responses in the 30 cm package drop scenario. This was accomplished by varying the drop orientation, fuel assembly type (17x17 PWR and 10x10 BWR), burnup, cladding temperature, spacer grid buckling load, package mass, impact limiter stiffness, and mechanical gap conditions within the basket. A MATLAB framework was developed to automate LS- DYNA model generation and execution on PNNL institutional computing resources. In total, over 2000 simulations were performed. For each simulation, the SNF response was quantified in terms of permanent grid deformation, fuel rod contact pressure, and strains within the fuel rods, guide tubes, and water rods. The results provide valuable insight into the range of responses that could be reasonably expected from SNF in the 30 cm drop scenario, as well as t

关键词： Dynamic Analysis finite and boundary element methods Numerical and Computational Reactor/Nuclear Structural Integrity

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STRUCTURAL DYNAMICS MODELING OF SPENT NUCLEAR FUEL DURING HYPOTHETICAL PACKAGE DROP EVENTS

STRUCTURAL DYNAMICS MODELING OF SPENT NUCLEAR FUEL DURING HY...

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ASME Pressure Vessels and Piping Conference (PVP)

作者： Kadooka, Kevin Fitzpatrick, James Klymyshyn, Nicholas Pacific Northwest Natl Lab Richland WA 99352 USA

ISBN: (纸本)9780791885352

The response of spent nuclear fuel (SNF) to hypothetical package drop events is of particular interest in the scope of spent fuel storage and transportation because of the mechanical shock encountered in such scenarios. Previous testing and modeling by the U.S. Department of Energy have demonstrated that the shock and vibration environment of normal shipping and handling conditions (excluding package drop events) is relatively benign and does not challenge the integrity of spent nuclear fuel. Cask drop events are worth considering because SNF packages are required to withstand free drops onto unyielding surfaces as part of their licensing basis. The acceleration experienced during drop events can be orders of magnitude higher, and thus more advanced models are needed to encompass potential nonlinear behavior of the fuel, such as spacer grid buckling and rod-to-rod impact. This work describes a number of finite element models developed to calculate the response of spent nuclear fuel to various hypothetical drop events that have been validated by package and fuel assembly drop tests conducted in the last decade. Sensitivity of the model response to factors such as package drop orientation, secondary impacts, and irradiated material properties, as well as their potential impacts to fuel cladding integrity, was also investigated. Cask drops are not expected as a regular occurrence during SNF transportation, but this work helps raise the understanding of SNF mechanical loads to the point of consistency with the package design requirements.

关键词： Dynamic Analysis finite and boundary element methods Numerical and Computational Reactor/Nuclear Structural Integrity

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SPENT NUCLEAR FUEL MECHANICAL LOADS IN THE GENERAL PACKAGE DROP SCENARIO

SPENT NUCLEAR FUEL MECHANICAL LOADS IN THE GENERAL PACKAGE D...

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ASME Pressure Vessels and Piping Conference (PVP)

作者： Klymyshyn, Nicholas Spitz, Casey Ivanusa, Pavlo Kadooka, Kevin Fitzpatrick, James Pacific Northwest Natl Lab Richland WA 99352 USA

ISBN: (纸本)9780791885352

The US Department of Energy Spent Fuel and Waste Science and Technology program is performing research to determine the mechanical loading conditions applied to spent nuclear fuel (SNF) during normal conditions of transportation to inform mechanical tests of SNF and close an important knowledge gap related to the practical disposition of SNF in the US. A recent multi-national collaborative test campaign measured SNF assembly impact response to the 30 cm horizontal package drop scenario, which is a common regulatory basis test of SNF package design. Researchers at Pacific Northwest National Laboratory (PNNL) are using the test data to validate explicit finite element models to calculate the mechanical loads and structural response of spent nuclear fuel assemblies in the as-tested 30 cm horizontal package drop scenario. Once the as-tested package drop model is validated, the next step is to apply the model to the general 30 cm drop scenario, which includes all impact angles, all fuel assembly types, and all burnup conditions. PNNL is developing a damage model that will incorporate the results of finite element parametric studies to establish trends in SNF mechanical loading to various input parameters, like impact orientation and burnup. The damage model will have the capability to estimate mechanical loads for any single set of input parameters, but it will first be used to describe the upper bounds of potential SNF loading in the 30 cm drop scenario. This paper describes PNNL's progress toward developing the general solution to the problem of spent nuclear fuel mechanical loads in the 30 cm package drop scenario, and it describes the next steps in closing the knowledge gap.

关键词： Dynamic Analysis finite and boundary element methods Numerical and Computational Reactor/Nuclear Structural Integrity

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Benchmark Analysis of Ductile Fracture Simulation for Circumferentially Cracked Pipes Subjected to Bending

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JOURNAL OF PRESSURE VESSEL TECHNOLOGY-TRANSACTIONS OF THE ASME 2022年第1期144卷 011509-011509页

作者： Kumagai, Tomohisa Miura, Yasufumi Miura, Naoki Marie, Stephane Almahdi, Remmal Mano, Akihiro Li, Yinsheng Katsuyama, Jinya Wada, Yoshitaka Hwang, Jin-Ha Kim, Yun-Jae Nagashima, Toshio Huh, Nam-Su Takahashi, Akiyuki Cent Res Inst Elect Power Ind Yokosuka Kanagawa 2400196 Japan Framatome France F-92084 Paris France Japan Atom Energy Agcy Tokai Ibaraki 3191195 Japan Kindai Univ Dept Mech Engn Fac Sci & Engn Higashiosaka Osaka 5778502 Japan Korea Univ Sch Mech Engn Seoul 136713 South Korea Sophia Univ Dept Engn & Appl Sci Fac Sci & Technol Tokyo 1028554 Japan Seoul Natl Univ Sci & Technol Dept Mech Engn Seoul 139743 South Korea Tokyo Univ Sci Dept Mech Engn Fac Sci & Technol Noda Chiba 2788510 Japan

To predict fracture behavior for ductile materials, some ductile fracture simulation methods different from classical approaches have been investigated based on appropriate models of ductile fracture. For the future use of the methods to overcome restrictions of classical approaches, the applicability to the actual components is of concern. In this study, two benchmark problems on the fracture tests supposing actual components were provided to investigate the prediction ability of simulation methods containing parameter decisions. One was the circumferentially through-wall and surface cracked pipes subjected to monotonic bending, and the other was the circumferentially through-wall cracked pipes subjected to cyclic bending. Participants predicted the ductile crack propagation behavior by their own approaches, including finite element method (FEM) employed Gurson-Tvergaard-Needleman (GTN) yielding function with void ratio criterion, are FEM employed GTN yielding function, FEM with fracture strain or energy criterion modified by stress triaxiality, extended FEM with J or Delta J criterion, FEM with stress triaxiality and plastic strain based ductile crack propagation using FEM, and elastic-plastic peridynamics. Both the deformation and the crack propagation behaviors for monotonic bending were well reproduced, while few participants reproduced those for cyclic bending. To reproduce pipe deformation and fracture behaviors, most of the groups needed parameters that were determined to reproduce pipe deformation and fracture behaviors in benchmark problems themselves and it is still difficult to reproduce them by using parameters only from basic materials tests.

关键词： fatigue and fracture prediction finite and boundary element methods inelastic analysis

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Closed-Form Stress Intensity Factor Solutions for Circumferential and Axial Surface Cracks With Large Aspect Ratios in Pipes

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JOURNAL OF PRESSURE VESSEL TECHNOLOGY-TRANSACTIONS OF THE ASME 2022年第6期144卷 061303-061303页

作者： Azuma, Kisaburo Li, Yinsheng Secretariat Nucl Regulat Author Regulatory Stand & Res Dept Minato Ku 1-9-9 Roppongi Tokyo 1068450 Japan Japan Atom Energy Agcy Shirakala 2-4 Tokai Ibaraki 3191195 Japan

The ASME Boiler and Pressure Vessel Code Section XI prescribes the stress intensity factor solutions at the surface and deepest points for a semi-elliptical crack. The ASME Code Section XI, however, provides no solutions for a crack with a large aspect ratio, that is a crack in which the crack depth a is larger than the half-length c. The difficulty in treating the crack with a large aspect ratio relates to the position of the maximum stress intensity factor, which appears at neither the surface point nor the deepest point. In this paper, we investigate the influence of the stress intensity factor at the maximum point for circumferential and axial inside surface cracks with a large aspect ratio in a cylinder. First, we obtain the influence coefficients G(i) for the stress intensity factor at the surface point, the deepest point, and the maximum point by finite element analysis, and developed a series of closed-form G(i) solutions. Three geometrical factors are considered as parameters affecting the influence coefficients G(i): aspect ratio (a/l = 0.5, 1.0, 2.0, and 4.0), crack depth ratio (a/t = 0.01, 0.1, 0.2, 0.2, 0.4, 0.6, and 0.8), and radius to thickness ratio (R-i/t = 2, 5, 10, 20, 40, and 80). Finally, we propose methods for evaluating the stress intensity factor for a crack with a large aspect ratio in a manner that characterizes the influence of the solutions at the maximum point.

关键词： fatigue and fracture prediction finite and boundary element methods

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FINGER FLANGE DESIGNS ON CAST EQUIPMENT

FINGER FLANGE DESIGNS ON CAST EQUIPMENT

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ASME Pressure Vessels and Piping Conference (PVP)

作者： Shitole, Bhaskar Heinrichs, Cynthia Wood Calgary AB Canada

ISBN: (纸本)9780791883822

Piping systems connecting critical equipment such as pumps with non-standard flanges should be designed so that all components have compatible strength. One such non-standard flange design is the so-called finger flange, used on the discharge flanges of large pumps. A finger flange uses slots instead of holes for the bolts. This design is common for certain types of equipment in use today, such as large slurry and water pumps. In this study, finite element analysis is used to model a finger flange bolted to a standard ASME B16.5 weldneck flange and understand the areas of weakness in the overall joint. Seating stresses caused by bolt load are calculated as well as stresses experienced by the joint during operation with additional pressure applied. Stresses are compared for the region of highest stress at the junction of the hub to the pipe shell. Various aspects of the geometry are modified to evaluate the effect on flange stress. The slots were found to have minimal effect on flange stress. Increasing the wall thickness reduces the stress in the finger flange. Bolting the finger flange to a thicker standard flange increases the stress in the finger flange. Uneven bolting was simulated by tightening a bolt and leaving the surrounding bolts loose. In this situation the finger flange experienced significantly higher stress than a standard flange exposed to the same uneven load. Gasket stress and displacement were similar between a finger flange joint and a standard joint.

关键词： Flange strength slurry pump bolted finite and boundary element methods FEA

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Liquid vibrations in cylindrical tanks with flexible membranes

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JOURNAL OF KING SAUD UNIVERSITY SCIENCE 2021年第8期33卷

作者： Choudhary, Neelam Kumar, Narveen Strelnikova, Elena Gnitko, Vasil Kriutchenko, Denys Degtyariov, Kyryl Bennett Univ Dept Math Greater Noida 201310 Uttar Pradesh India A Pidgorny Inst Mech Engn Problems Dept Hydroaeromech Power Machines Dm Pozharsky Str 2-10 UA-61046 Kharkiv Ukraine Kharkov Natl Univ Dept Phys & Energy Svobody Sq 4 UA-61022 Kharkov Ukraine

The objectives of this paper are in studying the liquid vibrations in rigid circular cylindrical shells with internal flexible membranes or covered by membranes. The liquid in the container is supposed to be an ideal and incompressible one, and the fluid motion is irrotational. In above formulated suppositions the velocity potential is introduced;it satisfies the Laplace equation. The boundary value problem is for-mulated for the velocity potential. To obtain boundary conditions on the liquid free surface, the mem-brane deflection is considered, and the equality of normal components of liquid and membrane velocities is satisfied. The incompressible and inviscid liquid is supposed to perform irrotational motion in the fluid domain divided into two sub-domains by internal flexible membrane that is installed at the given height. For solutions of the problems both numerical and analytical methods are in use. The ana-lytical solutions of two boundary value problems are obtained for unknown velocity potential and mem-brane deflection as the Fourier-Bessel series with coefficients depending on unknown frequency. Satisfying boundary conditions, we obtain the system of homogeneous algebraic equations. The condition of a non-trivial solution of this system gives the non-linear equation for evaluating the frequencies. The coupled membrane and liquid vibrations in cylindrical tanks are studied also by FEM and BEM methods. The comparison of results obtained using analytical approach with ones received with boundary and finite element method is provided. The main results are as follows. As follows from numerical simula-tions, if the membrane is installed inside the cylinder, then the most important parameter affecting the result, is the height of the membrane installation. If the membrane is installed at a considerable dis-tance from the free surface, then the sloshing frequency practically does not change, and more precisely, it slightly increases. The dependencies of frequencie

关键词： Liquid vibrations Rigid shell Flexible membrane Fourier-Bessel series finite and boundary element methods

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Analysis of the Thermal Stress at the Tubesheet in Floating-Head or U-Tube Heat Exchangers

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JOURNAL OF PRESSURE VESSEL TECHNOLOGY-TRANSACTIONS OF THE ASME 2017年第2期139卷 021601-021601页

作者： Liu, Jiuyi Qian, Caifu Li, Huifang Beijing Univ Chem Technol 15 North Third Ring Rd Beijing 100029 Peoples R China

Thermal stress is an important factor influencing the strength of a heat exchanger tubesheet. Some studies have indicated that, even in floating-head or U-tube heat exchangers, the thermal stress at the tubesheet is significant in magnitude. For exploring the value, distribution, and the influence factors of the thermal stress at the tubesheet of these kind heat exchangers, a tubesheet and triangle arranged tubes with the tube diameter of 25mm were numerically analyzed. Specifically, the thermal stress at the tubesheet center is concentrated and analyzed with changing different parameters of the tubesheet, such as the temperature difference between tube-side and shell-side fluids, tubesheet diameter, thickness, and the tube-hole area ratio. It is found that the thermal stress of the tubesheet of floating-head or U-tube heat exchanger was comparable in magnitude with that produced by pressures, and the distribution of the thermal stress depends on the tube-hole area and the temperature inside the tubes. The thermal stress at the center of the tubesheet surface is high when tube-hole area ratio is very low. And with increasing the tubehole area ratio, the stress first decreases rapidly and then increases linearly. A formula was numerically fitted for calculating the thermal stress at the tubesheet surface center which may be useful for the strength design of the tubesheet of floating-head or U-tube heat exchangers when considering the thermal stress. Numerical tests show that the fitted formula can meet the accuracy requirements for engineering applications.

关键词： finite and boundary element methods safety and reliability tubesheet design thermal stress floating head heat exchangers U-tube heat exchangers

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