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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.
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
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：74.46(Nuclear Science & Technology)no abstracts in English
*; 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
; ; ; ; Shinohara, Yoshikuni; ; ; ; ; Horiki, Oichiro
JAERI-M 84-137, 49 Pages, 1984/08
no abstracts in English
; ; ; Shinohara, Yoshikuni; ; ; ; *; Horiki, Oichiro
JAERI-M 84-056, 62 Pages, 1984/03
no abstracts in English
*; Shinohara, Yoshikuni
JAERI-M 84-025, 131 Pages, 1984/02
no abstracts in English
JAERI-M 9576, 32 Pages, 1981/07
no abstracts in English
JAERI-M 8579, 23 Pages, 1979/11
no abstracts in English
Journal of Nuclear Science and Technology, 10(12), p.753 - 761, 1973/12
no abstracts in English
Nakajima, Kunihiro*; Nagaya, Yasunobu; Sakon, Atsushi*; Sano, Tadafumi*; Hashimoto, Kengo*
no journal, ,
Reactor noise analysis have been performed with the MVP3.0 code for subcritical experiments at KUCA A-core. The prompt neutron decay constant 
has been calculated with Feynman- simulation capability of the code. It has been confirmed that the calculated values agree with the measured ones within the range of 10%.
