Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Sakon, Atsushi*; Nakajima, Kunihiro*; Takahashi, Kazuki*; Hohara, Shinya*; Sano, Tadafumi*; Fukaya, Yuji; Hashimoto, Kengo*
EPJ Web of Conferences, 247, p.09009_1 - 09009_8, 2021/02
In graphite-reflected thermal reactors, even a detector placed far from fuel region may detect a certain degree of the correlation amplitude. This is because mean free path of neutrons in graphite is longer than that in water or polyethylene. The objective of this study is experimentally to confirm a high flexibility of neutron detector placement in graphite reflector for reactor noise analysis. The present reactor noise analysis was carried out in a graphite-moderated and -reflected thermal core in Kyoto University Critical Assembly (KUCA). BF
proportional neutron counters (1" dia.) were placed in graphite reflector region, where the counters were separated by about 35cm and 30cm -thick graphite from the core, respectively. At a critical state and subcritical states, time-sequence signal data from these counters were acquired and analyzed by a fast Fourier transform (FFT) analyzer, to obtain power spectral density in frequency domain. The auto-power spectral density obtained from the counters far from the core contained a significant degree of correlated component. A least-squares fit of a familiar formula to the auto-power spectral density data was made to determine the prompt-neutron decay constant. The decay constant was 63.3
14.5 [1/s] in critical state. The decay constant determined from the cross-power spectral density and coherence function data between the two counters also had a consistent value. It is confirmed that reactor noise analysis is possible using a detector placed at about 35cm far from the core, as we expected.
Fukaya, Yuji; Nakagawa, Shigeaki; Goto, Minoru; Ishitsuka, Etsuo; Kawakami, Satoru; Uesaka, Takahiro; Morita, Keisuke; Sano, Tadafumi*
KURNS Progress Report 2018, P. 148, 2019/08
The Japan Atomic Energy Agency (JAEA) started the Research and Development (R&D) to improve nuclear prediction techniques for High Temperature Gas-cooled Reactors (HTGRs). The objectives are to introduce generalized bias factor method to avoid full mock-up experiment for the first commercial HTGR and to introduce reactor noise analysis to High Temperature Engineering Test Reactor (HTTR) experiment. To achieve the objectives, the reactor core of graphite moderation system named B7/4"G2/8"p8EUNU+3/8"p38EU(1) was newly composed in the B-rack of Kyoto University Critical Assembly (KUCA). The core plays a role of the reference core of the bias factor method, and the reactor noise was measured to develop the noise analysis scheme. In addition, training of operator of HTTR was also performed during the experiments.
Yamamoto, Toshihiro
Noizu Za Ribaibaru, p.165 - 171, 2001/11
no abstracts in English
PNC TN9410 97-011, 45 Pages, 1997/01
In the study for the development of the sub-criticality monitoring system for the nuclear fuel facilities, wavelet analysis was applied to detect the neutron multiplication system is approaching to critical. Neutron noise signal is the measured data for the monitoring, and the data was accumulated in the multi-channel scaler of the neutron detection system. From the point of view of the simplicity of numerical calculations of the MCS data, discrete wavelet transform by using the Cardinal spline functions was selected in the varaiety of wavelet funtions. Simulated noise data of the system without neutron multiplication was numerically produced and also transformed by the wavelet analysis procedure to be compared to the results from the nutron multiplication system. The approach to the critical can be detected by checking the difference of the two kinds of transformed results, with and without neutron multiplications. The method was applied to the neutron noise signal obtained at the Deuterium Critical Assembly(DCA), and it was confirmed that approaching to critical can be detected by tbe present method.
Hayashi, Koji; Shimazaki, Junya; Nabeshima, Kunihiko; Shinohara, Yoshikuni; Inoue, Kimio*;
JAERI-Research 95-015, 172 Pages, 1995/03
JAERI-Research-95-015.pdf:4.53MB
no abstracts in English
Hayashi, Koji
Tokei Suri Kenkyujo Kyodo Kenkyu Ripoto 68, 0, p.31 - 41, 1995/03
no abstracts in English
Hayashi, Koji; Shimazaki, Junya; Nabeshima, Kunihiko; Shinohara, Yoshikuni; Inoue, Kimio*;
JAERI-Research 95-004, 178 Pages, 1995/01
JAERI-Research-95-004.pdf:4.66MB
no abstracts in English
Suzudo, Tomoaki
JAERI-Research 94-003, 91 Pages, 1994/07
JAERI-Research-94-003.pdf:2.66MB
no abstracts in English
Hayashi, Koji; Shimazaki, Junya; Nabeshima, Kunihiko; Shinohara, Yoshikuni; Inoue, Kimio*;
JAERI-M 93-194, 163 Pages, 1993/10
no abstracts in English
Suzudo, Tomoaki
JAERI-M 93-137, 13 Pages, 1993/07
no abstracts in English
Hayashi, Koji
JAERI-M 93-041, 152 Pages, 1993/03
no abstracts in English
Suzudo, Tomoaki
Nuclear Science and Engineering, 113, p.145 - 160, 1993/02
Times Cited Count：12 Percentile：74.44(Nuclear Science & Technology)no abstracts in English
Hayashi, Koji
Nihon Genshiryoku Gakkai-Shi, 34(10), p.971 - 983, 1992/10
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)no abstracts in English
*; ; ; ; Fukami, Akihiro*; *; Igawa, Kenichi*
PNC TN9410 91-175, 52 Pages, 1991/05
An acoustic detection method is one of the FBR reactor core malfunction detection methods, and is regarded as being promising. In this study, the preliminary experiment of boiling detection by acoustic method was conducted at JOYO to measure the acoustic signal level and to investigate the applicability of the acoustic method. The experiment was performed on June 13 and 14, 1990 during the 8th periodic inspection of JOYO. The results obtained though the experiment are as follows: (1)Sodium bubbling (boiling) induced by the electric heater was detected as the fluctuation of temperature single of the thermocouple attached to surface of the electric heater. (2)Bubbling single of the acoustic detector could not be identified cleary because of the high background noise caused by the primary main pump vibration, sodium flow in the reacter vessel and the electric supply in the containment vessel. (3)The correlation between the signal of the acoustic detector or the fluctuation of temperature signal of the thermocouple and the flow rate of the primary loops was not ascertained. It became clear through this study that the validity of the reactor core malfunction detction by acoustic method depend on the peculiar noise level in the reactor vessel, and the reduction of noise is the subject for a future study.
*; Kyoya, Masahiko; *; *
JAERI-M 91-021, 61 Pages, 1991/03
no abstracts in English
Hayashi, Koji; Shinohara, Yoshikuni; Suzuki, Katsuo; Nabeshima, Kunihiko
JAERI-M 89-175, 90 Pages, 1989/10
no abstracts in English
*
JAERI 1292, 46 Pages, 1984/09
no abstracts in English
; ; ; ; Shinohara, Yoshikuni; ; ; ; ; Horiki, Oichiro
JAERI-M 84-137, 49 Pages, 1984/08
no abstracts in English
JAERI-M 84-084, 24 Pages, 1984/04
no abstracts in English
; ; ; Shinohara, Yoshikuni; ; ; ; *; Horiki, Oichiro
JAERI-M 84-056, 62 Pages, 1984/03
no abstracts in English
