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Kasahara, Naoto; Iwata, Koji; Imazu, Akira; Horikiri, Morito; Tokura, Sunao*
PNC TN9410 90-032, 321 Pages, 1989/12
Tubesheet structures are one of the most critical portions in the LMFBR components, and also have complicated configurations. Consequently, the specialized evaluation methods are required for design of tubesheets. In the case of structural design of the prototype LMFBR "Monju", the tentative design evaluation method had been suggested. It is the purpose of this study to propose the advanced method, that can be applied to designs of condenced tubesheets and of higher temperature operating ones, which are required in the demonstration LMFBR. As a conventional design method, ASME Sec. III A-8000 is basicaly adopted in the world. A-8000, however, is the elastic design method for LWR where main loading is inner pressure. For a design of tubesheets in LMFBR, It is necessary to make A-8000 adopted to thermal stress and to develop inelastic strain calculation methods. In this study we clarified the application range of A-8000 and proposed the improved method to calculate thermal stresses. The elastic design method based on perforated palate models without A-8000 is also developed. To evaluate inelastic responses of material, the relation between inelastic strain amplifications around holes of tubesheets and ligament efficiencies is obtained in the view point of dependence of inelastic behavior on ligament efficiencies. As the results, we developed the inelastic strain concentration factor which have consistency with the general purpose high temperature design code.
Kasahara, Naoto; Tokura, Sunao*; Iwata, Koji; Horikiri, Morito; Imazu, Akira
PNC TN9410 88-037, 169 Pages, 1988/02
Tubesheet Structures of Heat Exchanger is one of the most important structures in the Fast Breeder Reactor Plants, and simplified analysis methods for design are necessary because of those complex structures. The conventional method exists in ASME Code Sec. III A-8000, which is only available for elastic analysis. In this study we developed simplified inelastic analysis methods on tubesheet structures using the equivalent inelastic properties of perforated region. To define the equivalent elastoplastic stress-strain relation we adopted the Ludwik type equation. And Igari's creep strain equation on perforated plates was examined, which proves to be conservative. As the application of these properties this study proposed two simplified models. The one is equivalent axisymmetric solid plate model to evaluate junction between rim and shroud. The other is partially perforated equivalent solid plate model to evaluate the outermost holes. These models were validated by comparison with thermal transient test data.
Kasahara, Naoto; Horikiri, Morito; Iwata, Koji; Uno, Tetsuro*; Imazu, Akira; Tokura, Sunao*
PNC TN9410 87-057, 245 Pages, 1987/03
The structural design methods for tubesheets have been studied in connection with the development of fast breeder reactors, because tubesheet structures have complex and 3-dimmensional configulation, and are subjected to severe thermal loading. In Japan the tentative guidelines for structural design methods for tubesheets of FBR plants are proposed by the task group on the design methods of tubesheets in Power Reactor and Nuclear Fuel Development Corporation. The objective of this study is to validate this tentative methods by using data obtained from thermal transient tests of tubesheet models of evaporator and detailed analytical study, and moveover to provide usuful knowledge to rationalize the tentative guidelines. In this report, simplified methods of thermal and stress analyses for tubesheet structures are newly proposed and applied to thermal transient tests of tubesheet models which were carried out in 1984. The works contained in this report are summarized as; (1)Heat transfer analyses with 3-dimensional full model and elastic analyses with the same model are executed on the tubesheet structure, and the mechanism of thermal stress generation in the tubesheets is clarified. (2)Two simplified heat transfer analysis models are developed: the convection film model and the modified perforated plate model. Tbose models are proved to be accurate enough through the comparison with the results of 3-dimensional analyses. (3)Heat-transfer coefficient on the tubesheet structures are discussed with the data of temperature tests and thermal-hydraulicanalyses. As the results, it is shown that the film heat-transfer formula for turbulent flow inside tubes canbe used conservatively for inner surface of shrouds. (4)The simplified inelastic analysis method for tubesheets is developed. This method uses 2-dimensional models considering 3-dimensional effects of shrouds. As the results of comparison with the thermal transient test data of tubesheet model, the ...
