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Katano, Ryota; Yamanaka, Masao*; Pyeon, C. H.*
Journal of Nuclear Science and Technology, 57(2), p.169 - 176, 2020/02
Times Cited Count:4 Percentile:40.43(Nuclear Science & Technology)We proposed the linear combination method as a subcriticality measurement method which estimates the prompt neutron decay constant () correlated with the subcriticality using measurement results obtained at multiple detector positions. In the previous study, we confirmed applicability of the linear combination method through the pulsed neutron experiment with DT neutron source at Kyoto University Critical Assembly (KUCA). In this study, we conduct the pulsed neutron source experiment with spallation neutrons at KUCA and confirm the robustness of the linear combination to neutron sources.
Katano, Ryota; Yamanaka, Masao*; Pyeon, C. H.*
Nuclear Science and Engineering, 193(12), p.1394 - 1402, 2019/12
Times Cited Count:5 Percentile:48.18(Nuclear Science & Technology)The author proposed the linear combination method as a subcriticality measurement method which estimates the prompt neutron decay constant (alpha) correlated with the subcriticality using measurement results obtained at multiple detector positions. In this study, we conduct the pulsed neutron experiment at Kyoto University Critical Assembly (KUCA) and measure alpha by the linear combination method using measured neutron counts. Through experiment, we experimentally show that the linear combination method can reduce the higher-mode effect compared to the conventional method. In addition, experimentally show that the linear combination has capability of the different mode extraction.
Katano, Ryota
Nuclear Science and Engineering, 193(4), p.431 - 439, 2019/04
Times Cited Count:6 Percentile:54.98(Nuclear Science & Technology)We proposed "linear combination method" to reduce the higher order mode effect on the prompt neutron decay constant measured by the pulsed neutron experiment. When the spatial higher order mode effect is taken into account, the time evolution of the neutron counts after the pulsed neutron injection is given by linear combination of multiple exponential functions. However, the measurement results by the conventional method include the systematic error derived from the higher order mode effect because the conventional method fit the neutron counts with a single exponential function. The proposed method extract the single exponential function of the fundamental mode by linear combination of the neutron counts at multiple detectors, thus the proposed method reduces the higher order mode effect. As the verification, we applied the proposed method to the numerical simulation. The results indicate that the proposed method can reduce the higher order mode effect by linear combination.
Nagaya, Yasunobu
Proceedings of Joint International Conference on Mathematics and Computation, Supercomputing in Nuclear Applications and the Monte Carlo Method (M&C + SNA + MC 2015) (CD-ROM), 9 Pages, 2015/04
A new method to calculate the prompt neutron decay constant () with the Monte Carlo method is proposed. It is based on the conventional - search algorithm but no iteration is required for the value search. The eigenvalue is expressed in the truncated Taylor series with regard to ; the differential coefficients are calculated with the differential operator sampling, which is one of the Monte Carlo perturbation techniques. In order to examine the applicability of the proposed method, verification has been performed for simple geometries of a bare fast system (Godiva) and an unreflected thermal system (STACY). Comparisons has been done with the pulsed neutron source (PNS) simulation and the direct calculation from the definition of the value. The results with the proposed method show good agreement with the reference PNS simulation.
Yamashita, Kiyonobu; Shindo, Ryuichi; Murata, Isao; Nakata, Tetsuo*
JAERI-M 89-198, 42 Pages, 1989/12
no abstracts in English
; *; ;
JAERI-M 9942, 60 Pages, 1982/02
no abstracts in English
; ; ;
JAERI-M 9911, 32 Pages, 1982/02
no abstracts in English
Katano, Ryota
no journal, ,
no abstracts in English
Katano, Ryota
no journal, ,
We have proposed the linear combination method for accurate prompt neutron decay constant measurement, which improves accuracy of the fitting method using pulsed neutron source (PNS). In this study, we perform PNS simulation with a continuous energy Monte Carlo code to confirm applicability of the proposed method to ADS core. The results indicate that thermal neutrons, which have less contribution to fissions, have long lifetime due to small absorption cross sections of LBE nuclides and could degrade accuracy of .