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Sakamoto, Yoshiteru; Shirai, Hiroshi; Fujita, Takaaki; Ide, Shunsuke; Takizuka, Tomonori; Oyama, Naoyuki; Kamada, Yutaka
Plasma Physics and Controlled Fusion, 46(5A), p.A299 - A304, 2004/05
Times Cited Count：74 Percentile：88.76(Physics, Fluids & Plasmas)no abstracts in English
Nakatani, Takeshi; Agui, Akane; Yoshigoe, Akitaka; Matsushita, Tomohiro*; Takao, Masaru*; Aoyagi, Hideki*; Takeuchi, Masao*; Tanaka, Hitoshi*
AIP Conference Proceedings 705, p.290 - 293, 2004/00
We have developed a new method to extract only the orbit fluctuation caused by changing magnetic field error of an insertion device (ID). This method consists of two main parts. (i) The orbit fluctuation is measured with modulating the error field of the ID by using the real-time beam position measuring system. (ii) The orbit fluctuation depending on the variation of the error field of the ID is extracted by the filter applying the Wavelet Transform. We call this approach the amplitude modulation method. This analysis technique was applied to measure the orbit fluctuation caused by the error field of APPLE-2 type undulator (ID23) installed in the SPring-8 storage ring. We quantitatively measured two kinds of the orbit fluctuation which are the static term caused by the magnetic field error and the dynamic term caused by the eddy current on the ID23 chamber.
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JNC TJ7400 2000-001, 79 Pages, 2000/02
JNC-TJ7400-2000-001.pdf:3.07MB
no abstracts in English
Kasahara, Naoto; Yacumpai, A.*; Takasho, Hideki*
JNC TN9400 99-019, 34 Pages, 1999/02
At incomplete mixing area of high temperature and low temperature fluids near the surface of structures, temperature fluctuation of fluid gives thermal fatigue damage to wall structures. This thermohydraulic and thermomechanical coupled phenomenon is called thermal striping, which has so complex mechanism and sometimes causes crack initiation on the structural surfaces that rational evaluation methods are required for screening rules in design codes. In this study, frequency response characteristics of structures and its mechanism were investigated by both numerical and theoretical methods. Based on above investigation, a structural response diagram was derived, which can predict stress amplitude of structures from temperature amplitude and frequency of fluids. Furthermore, this diagram was generalized to be the Non-dimensional structural response diagram by introducing non-dimensional parameters such as Biot number, non-dimensional frequency, and non-dimensional stress. The use of the Non-dimensional structural response diagram appears to evaluate thermal stress caused by thermal striping, rapidly without structural analysis, and rationally with considering attenuation by non-stationary heat transfer and thermal unloading. This diagram can also give such useful information as sensitive frequency range to adjust coupled thermohydraulic and thermomechanical analysis models taking account of four kinds of attenuation factors: turbulent mixing, molecular diffusion, non-stationaly heat transfer, and thermal unloading.
; Shiraiwa, Shunichi*; Hoshino, Katsumichi; Miura, Yukitoshi; Hanada, Kazuaki*; ; JFT-2M Group
Japanese Journal of Applied Physics, Part 1, 36(12A), p.7367 - 7374, 1997/12
Times Cited Count：13 Percentile：56.99(Physics, Applied)no abstracts in English
PNC TN9410 97-039, 187 Pages, 1997/05
A numerical evaluation system, which is consisted of four codes, AQUA, DINUS-3, THEMIS and BEMSET has been developed for thermal striping phenomena. To validate the system for the phenomena, thermally fluid - structure interaction analysis was carried out using a existing sodium experiment of parallel impinging jet simulating the outlet region of an LMFBR core. Calculational results on the RMS values of temperature fluctuation, the histograms of temperature amplitudes and frequencies, the auto-power spectral density distributions of temperature fluctuations and the damping characteristics of temperature fluctuations showed good agreement with the measured values under the test conditions of various flow velocity. From the comparisons with the experimental data, it was concluded that the numerical evaluation system is applicable to the evaluation of thermally fluid - structure interaction phenomena related to the thermal striping.
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PNC TN9410 97-013, 111 Pages, 1997/01
Since the 54-rod cluster high-burnup fuel assemblies are planing to be loaded in Fugen, it must be confirmed that the mechanical integrity of the assemblies will be retained during the dwelling period in the reactor core. In the integrity verification, the confirmation that fretting wear, which occurs on fuel cladding surface at the contact with the spacer ring-elements, will not exceed the design margin is important. Accurate measurements of the flow-induced vibration characteristics under the hydraulic condition of coolant simulating the reactor core, especially measurements of the vibration amplitude, is necessary because the vibration amplitude directly affects the fretting wear depth. The flow-induced vibration measurements of the 54-rod cluster high-burnup fuels in which accelerometers were installed, were carried out under the various hydraulic conditions in the Component-Test-Loop (CTL). The results of the measurements are discribed in this papers. From the frequency analysis, the characteristic frequency of the fuel was observed around 105 Hz and 160 Hz. This frequency approximately coincided with that estimated by the fretting wear analysis code. The amplitude of flow-induced vibration was increased with increase in total flow rate and steam quality. Though these tendencies coincided with the results calculated by the analysis code, the amplitude measured at the region of low flow rate tended to be large compared with the calculated values. It was confirmed that this difference can be reduced on the safety side by the modification of the equation in the analysis code. The Paidoussis equation is divided into two terms in this modification, in which one term depending on total flow rate and the other term depending on steam quality, and proper coefficients are determined for each term. Though the amplitudes of flow-induced vibration for this fuel were larger than for either of the 28-rod cluster fuel of Fugen and 36-rod cluster fuel of ATR demonstration ...
Fujimura, Kaoru; R.E.Kelly*
J. Fluid Mech., 331, p.261 - 282, 1997/00
Times Cited Count：4 Percentile：25.91(Mechanics)no abstracts in English
Fujimura, Kaoru; R.E.Kelly*
Phys. Fluids, 7(1), p.68 - 79, 1995/01
Times Cited Count：29 Percentile：74.13(Mechanics)no abstracts in English
Fujimura, Kaoru; R.E.Kelly*
J. Fluid Mech., 246, p.545 - 568, 1993/00
Times Cited Count：26 Percentile：74.02(Mechanics)no abstracts in English
Fujimura, Kaoru;
Nihon Butsuri Gakkai-Shi, 47(10), p.798 - 805, 1992/10
no abstracts in English
Fujimura, Kaoru; R.E.Kelly*
Bifurcation Phenomena and Chaos in Thermal Convection, p.73 - 83, 1992/00
no abstracts in English
Fujimura, Kaoru
European Journal of Mechanics B, Fluids, 11(4), p.461 - 464, 1992/00
no abstracts in English
; Fujimura, Kaoru
J. Fluid Mech., 234, p.651 - 667, 1992/00
Times Cited Count：21 Percentile：67.84(Mechanics)no abstracts in English
Fujimura, Kaoru
Philos. Trans. R. Soc. Lond., Ser. A, 340, p.95 - 130, 1992/00
no abstracts in English
; ; Kawata, Tomio
PNC TN8410 92-012, 47 Pages, 1991/12
[Purpose] We confirmed that modified (6000rpm type) centrifugal clarifier arose the unstable vibration during the reduction of rotating speed under the condition of bearing undissolved residue after the clarification operation. This report describes the cause of unstable vibration that arise in the clarification body set on the rack which induced resonance vibration and the measurement results of vibration characteristic after taking countermeasure for vibration decrease. [Method] It was considered that the causes of the unstable vibration were following; (1)Unbalance between damping force of the lower bearing damper and the vibration force arisen by the rotational bowl (2)Effect of feed condition (3)Effect of self-excited vibration of the free liquid surface (4)Effect of frame strength The test has been conducted to make quantitative measure of vibration characteristic (amplitude of the rotational bowl and shaft) by changing the load in the rotational bowl. We also conducted the test to reconfirm the effect of the circumferential baffle plate which has shown the most effective effect to the vibration decrease in the preceding report. [Results] The effects of the circumferential baffle plate placed on the inside wall of the rotational bowl are shown as follows; (1)The unstable vibration during the reduction of rotating speed has been suppressed By this result, we verified that the vibration on the free liquid surface in the rotational bowl caused the vibration for the bowl without the circumferential baffle plate. (2)It was able to run the clarification operation in the standard condition(100
/h 
6h) for the rotational speed ranging from 4000 to 6000rpm. [Conclusion] By the results of this test and of the preceding report, the feed condition and the condition of setting the circumferential baffle plate are showed in the following, considering the aspects of rotational stability. (1)Condition of feed nozzle - feed 55㎜ in height from the lower ...
; Yasu, Takami; Kawata, Tomio
PNC TN8410 91-325, 68 Pages, 1991/11
[Purpose] We confirmed modified (6000rpm type) centrifugal clarifier happened unstable vibration in the downward rotation on the condition of including undissolved residue after the clarification operation. This report describes the cause of unstable vibration and the measurement results of vibration characteristic after taking countermeasure for vibration decrease. [Method] It was considered that the cause of unstable vibration was four items in the following. (1)Unbalance between damping force of lower bearing damper and vibration force arisen by rotational bowl (2)Effect of feed condition (3)Effect of self-excited vibration on the free surface (4)Effect of frame strength that be set modified. This test is for take countermeasure to each item (1
3 item) in the upper items, and for quantitative measure of vibration characteristic (amplitude of rotational bowl and shaft) in the downward rotation on the condition of including undissolved residue after the clarification operation and for select best countermeasure, that is most effective to vibration damping, and does not arise the fall of clarification performance (capture efficiency), the increase of leak rate of feed solution and the fall of sludge washing performance. [Results] (1)We could not confirme vibration damping, compared with spring constant k=9 kgf/cm, damping constant c=20㎏f
s/cm and the former condition (k=600 kgf/cm, c=0.3 kgfs/cm). (2)In case of countermeasure that operate as balance ring by sludge cohering height on the inside wall of rotational bowl, we could confirm that the amplitude in the downward rotation is about 1/3, the leak rate of feed solution is about 1/6, compared with the case of feed solution 55㎜ in height from the lower plate of rotational bowl and the former condition (25mm in height from the lower plate of rotational bowl). (3)Compared with the case of setting the side baffle plate 150㎜ in height from the lower plate of rotational bowl for decreasing ...
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Nucl.Eng.Des./Fusion, 3, p.59 - 62, 1985/00
Times Cited Count：1 Percentile：23.80(Nuclear Science & Technology)no abstracts in English
Sekihara, Takayasu
no journal, ,
Choi, B.; Nishida, Akemi
no journal, ,
To validate analysis models against actual phenomena is an important issue in improving the reliability of the seismic safety evaluation. In this work, firstly, we analyze seismic observation records in the target Nuclear Power Plant (NPP) building. In order to validate three dimensional finite element models of the target plant, seismic response analyses using the same input waves as the records are conducted, and a Fourier amplitude ratio of the response acceleration on each floor is compared between the analysis and the observation. By introducing the Fourier amplitude ratio between different floors, the amplification of the response acceleration is quantified, and more detailed comparisons between the analysis results and the observation records are enabled. Through this comparison, it is confirmed that in the analysis results, the amplification of the response acceleration at the frequency ranges of 3-4 Hz (primarly mode) and 8-9 Hz (secondary mode) is consistent with the observation records.
