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Tsutsumi, Hideaki*; Yamada, Hiroyuki; Mori, Kazunari*; Ebisawa, Katsumi; Shibata, Katsuyuki
JAERI-Tech 2000-086, 93 Pages, 2001/02
JAERI-Tech-2000-086.pdf:6.56MB
no abstracts in English
Tsutsumi, Hideaki*; Yamada, Hiroyuki; Ebisawa, Katsumi; Shibata, Katsuyuki
JAERI-Tech 2000-045, 107 Pages, 2000/07
JAERI-Tech-2000-045.pdf:7.25MB
no abstracts in English
Mori, Koji*; Neyama, Atsushi*; *; Nishimura, Kazuya*
PNC TJ1458 97-003, 179 Pages, 1997/02
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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 ...
Yamaguchi, Akira
PNC TN9410 94-070, 51 Pages, 1994/02
Seismic fragilities of equipment and systems are evaluated in a seismic probabilistic safety analysis (PSA). The seismic fragility is defined as the failure probability and its uncertainty at various ground acceleration levels. One evaluates the seismic fragility efficiently by making most use of available information in the seismic PSA. This study is related to a Bayesian inference method to reflect the information to the seismic fragility evaluation. Information that can be used in the Bayesian inference is (1)seismic experience data, (2)expert judgment on the seismic fragility, (3)seismic test data. The generic fragility database was used as the prior fragility that was to be updated. The acceleration level of the seismic experience and test data is much lower than the median value of the seismic capacity level of equipment. However, it is useful to cut down the lower tail of the fragility curves thus the modeling uncertainty. As the results, it is has been found that the annual frequency of failure that is calculated by the convolution of the fragility with seismic hazard curves is reduced considerably. Furthermore, the author has proposed the concept of entropy to quantify the value of the information used in the Bayesian inference. The combined use of the Bayesian inference and the entropy is a useful method to propose a cost-effective seismic test for the fragility evaluation. Findings obtained from the seismic PSA are taken into consideration in achieving more reasonable safety design. It should be noted that the findings are strongly affected by the uncertainty. Hence the reduction is necessary of the uncertainty of the contributive equipment from the viewpoint of seismic safety. Specific analysis and test of the contributive equipment is an effective way of reducing the uncertainty.
*; *; Imazu, Akira
PNC TN9410 88-080, 132 Pages, 1988/06
A series of analytical investigations were made into the seismic response characteristics of bellows, as a part of work aiming at establishing reliable seismic design and analysis methodologies for bellows piping systems. Simplified calculation methods were developed for the axial and lateral seismic response of bellows, in which bellows is modeled as an equivalent rod or beam, respectively. Using these methods, spectral response analyses were performed on the bellows with the number of convolutions as a parameter, and the results were compared with detailed FEM analysis by FINAS. Analyses were also made to compare with available vibration test data. The simplified methods were found to give fairly good results when compared with those by FINAS, and relatively conservative results when compared with experimental data. Through this study, simplified methods were established to evaluate the seismic response and stress of bellows with sufficient accuracy for practical design use.