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Journal Articles

Basic performance tests on vibration of support structure with flexible plates for ITER tokamak device

Takeda, Nobukazu; Kakudate, Satoshi; Shibanuma, Kiyoshi

Purazuma, Kaku Yugo Gakkai-Shi, 81(4), p.312 - 316, 2005/04

http://ci.nii.ac.jp/naid/110006281933

The vibration experiments of the support structures with flexible plates for the ITER major components such as toroidal field coil and vacuum vessel were performed using small-sized flexible plates aiming to obtain its basic mechanical characteristics such as dependence of the stiffness on the loading angle. The experimental results obtained by the hammering and frequency sweep tests were agreed each other, so that the experimental method is found to be reliable. In addition, the experimental results were compared with the analytical ones in order to estimate an adequate analytical model. As a result, the bolt connection strongly affected on the stiffness of the support structure. After studies of modeling the bolts, it is found that the analytical results modeling the bolts with finite stiffness only in the axial direction and infinite stiffness in the other directions agree well with the experimental ones. Using this model, the stiffness of the support structure for the ITER major components can be calculated precisely in order to estimate the dynamic behaviors.

JAEA Reports

Plan of vibration tests for estimation of seismic performance of ITER tokamak

Takeda, Nobukazu; Nakahira, Masataka

JAERI-Tech 2004-073, 59 Pages, 2005/01

JAERI-Tech-2004-073.pdf:11.36MB

The ITER toamak is composed of major components such as superconducting magnet and vacuum vessel whose operation temperatures are changed from room temperature to 4 K and room temperature to 200 $^{circ}$ C, respectively. The gravity support of the tokamak is flexible in order to accept the thermal deformation caused by temperature change. This structural feature causes the complex behaviors of the tokamak during seismic events. Therefore, the mechanical characteristics of the flexible support have to be investigated in detail. The present report describes the global plan of the series of vibration tests to estimate the seismic performance of the ITER tokamak. Although it is ideal that the vibration tests are carried out using a full-scale model, scale models are planned due to the limitation of the test facilities. The test results can be estimated by a scaling law. When the scaling law cannot be applied to some performances, the test is performed using a full-scale model. In addition, the other tests such as vacuum vessel and small-scaled models of the support structure are also planned.

JAEA Reports

Dynamic analysis of ITER tokamak based on results of vibration test using scaled model

Takeda, Nobukazu; Kakudate, Satoshi; Nakahira, Masataka

JAERI-Tech 2004-072, 43 Pages, 2005/01

JAERI-Tech-2004-072.pdf:6.06MB

The vibration experiments of the support structures with flexible plates for the ITER major components such as the vacuum vessel (VV) and the toroidal field (TF) coil were performed aiming to obtain its basic mechanical characteristics. Based on the experimental results, numerical analysis regarding the actual support structure was performed and a simplified model of the support structure was proposed. A support structure was modeled by only two spring elements. The stiffness calculated by the spring model agrees well with that of shell model, simulating actual structures based on the experimental results. It is therefore found that the spring model with the only two values of stiffness enables to simplify the complicated support structure with flexible plates. Using the spring model, the dynamic analysis of the VV and TF coil were performed to estimate the integrity under the design earthquake. As a result, the maximum relative displacement of 8.6 mm between VV and TF coil is much less than designed clearance, 100 mm, so that the integrity of the components is ensured.

Journal Articles

Design and structural analysis of support structure for ITER vacuum vessel

Takeda, Nobukazu; Omori, Junji*; Nakahira, Masataka; Shibanuma, Kiyoshi

Journal of Nuclear Science and Technology, 41(12), p.1280 - 1286, 2004/12

https://doi.org/10.1080/18811248.2004.9726357

The vibration experiments of the support structures with flexible plates for the ITER major components such as toroidal field coil and vacuum vessel were performed using small-sized flexible plates aiming to obtain its basic mechanical characteristics such as dependence of the stiffness on the loading angle. The experimental results obtained by the hammering and frequency sweep tests were agreed each other, so that the experimental method is found to be reliable. In addition, the experimental results were compared with the analytical ones in order to estimate an adequate analytical model. As a result, the bolt connection strongly affected on the stiffness of the support structure. After studies of modeling the bolts, it is found that the analytical results modeling the bolts with finite stiffness only in the axial direction and infinite stiffness in the other directions agree well with the experimental ones. Using this model, the stiffness of the support structure for the ITER major components can be calculated precisely in order to estimate the dynamic behaviors.

Journal Articles

Numerical evaluation of experimental models to investigate the dynamic behavior of the ITER tokamak assembly

Onozuka, Masanori*; Takeda, Nobukazu; Nakahira, Masataka; Shimizu, Katsusuke*; Nakamura, Tomomichi*

Fusion Engineering and Design, 69(1-4), p.757 - 762, 2003/09

https://doi.org/10.1016/S0920-3796(03)00139-X

Times Cited Count：2 Percentile：19(Nuclear Science & Technology)

The dynamic behavior of the ITER tokamak assembly has been investigated. Three experimental models have been considered to validate the numerical analysis methods for the dynamic events, mainly seismic events. A 1/8-scaled tokamak model, which is based on the 1998 ITER design, is under construction. Non-linear vibration characteristics, such as damping, can only be identified by a full-scale model. Therefore, a full-scale gravity support structure for the coil system has been designed and will be tested. In addition, for the sub-scaled tokamak model, the VV is assumed to be a rigid structure. This assumption is to be verified using a 1/20-scaled model. The above experimental models and their testing conditions have analytically and numerically evaluated. For example, both the static and dynamic spring constants obtained by static analysis and eigen-value analysis, respectively, were evaluated to be in good agreement.

JAEA Reports

Findings of the reactor automatic shutdown caused by a signal of a primary coolant flow rate of the PPWC:Low in the HTTR

Takamatsu, Kuniyoshi; Nakazawa, Toshio; Furusawa, Takayuki; Homma, Fumitaka; Saito, Kenji; Kokusen, Shigeru; Kamata, Takashi; Ota, Yukimaru; Ishii, Yoshiki; Emori, Koichi

JAERI-Tech 2003-062, 94 Pages, 2003/06

JAERI-Tech-2003-062.pdf:26.47MB

no abstracts in English

Journal Articles