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Zablackaite, G.; Shiotsu, Hiroyuki; Kido, Kentaro; Sugiyama, Tomoyuki
Nuclear Engineering and Technology, 56(2), p.536 - 545, 2024/02
Times Cited Count:1 Percentile:75.38(Nuclear Science & Technology)Kaburagi, Masaaki; Miyamoto, Yuta; Mori, Norimasa; Iwai, Hiroki; Tezuka, Masashi; Kurosawa, Shunsuke*; Tagawa, Akihiro; Takasaki, Koji
Journal of Nuclear Science and Technology, 9 Pages, 2024/00
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)Fukuda, Kodai; Yamane, Yuichi
Journal of Nuclear Science and Technology, 60(12), p.1514 - 1525, 2023/12
Times Cited Count:1 Percentile:34.39(Nuclear Science & Technology)This study aims to clarify the effect of fuel particle radius on the criticality transient behavior and the total number of fissions in water-moderated solid fuel dispersion systems. Neutronics/thermal hydraulics-coupled kinetics analysis was performed in a hypothetical fuel debris system, where small fuel particles aggregate in water and become supercritical. Results showed that the number of fissions is 10 times larger when the fuel particle radius is reduced by one order of magnitude under conditions where heat transfer, i.e. from fuel to water, is emphasized. Moreover, there is a possibility that lower reactivity could give a larger number of fissions when the fuel particle size is very small. In addition, the number of fissions may be overestimated or underestimated to an unexpected extent unless appropriate fuel particle size is set on the analysis.
Ito, Ayumi*; Yamashita, Susumu; Tasaki, Yudai; Kakiuchi, Kazuo; Kobayashi, Yoshinao*
Journal of Nuclear Science and Technology, 60(4), p.450 - 459, 2023/04
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)Yamane, Yuichi
Journal of Nuclear Science and Technology, 59(11), p.1331 - 1344, 2022/11
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)The reactivity was estimated from a time profile of neutron count rate or a simulated data in a quasi-steady state after sudden change of reactivity or external neutron source strength. The estimation was based on the equation of power in subcritical quasi-steady state. The purpose of the study is to develop the method of timely reactivity estimation from complicated time profile of neutron count rate. The developed method was applied to the data simulating neutron count rate created by using one-point kinetics code, AGNES, and Poisson-distributed random noise and to the transient subcritical experiment data measured by using TRACY. The result shows that the difference of the estimated and reference value was within about 5% or less for (
-1) for simulated data and within about 7% or less for
-1.4 and -3.1 for the experimental data. It was also shown that the possibility of the reactivity estimation several ten seconds after the status change.
Takezawa, Hiroki*; Tuya, D.; Obara, Toru*
Nuclear Science and Engineering, 195(11), p.1236 - 1246, 2021/11
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)This study introduces new methodologies for integrating fission reactions induced by delayed neutrons into the Multi-Region Integral Kinetic (MIK) code by using a Monte Carlo neutron transport calculation. First, it was confirmed that it is feasible to solve the Integral Kinetic Model (IKM) with delayed neutrons by the forward Euler discretization method in terms of the number of time steps. This can be done with the help of the law of radioactive decay to reflect the delay in the emission of delayed neutrons in the discretized IKM. Second, a new Monte Carlo-based methodology was introduced for calculating the cumulative distribution functions of secondary fission induced by prompt and delayed neutrons. These functions are necessary for the discretized IKM. The results of preliminary verification using the Godiva reactor confirmed the applicability of the new Monte Carlo-based methodology.
Yamane, Yuichi
Journal of Nuclear Science and Technology, 57(8), p.926 - 931, 2020/08
Times Cited Count:1 Percentile:9.57(Nuclear Science & Technology)An equation of power in subcritical quasi-steady state has been derived based on one-point kinetics equations for the purpose of utilizing it for the development of timely reactivity estimation from complicated time profile of neutron count rate. It linearly relates power, , to a new variable
, which is a function of time differential of the power. It has been confirmed by using one-point kinetics code, AGNES, that the calculated points (
) are perfectly in a line described by the new equation and that points (
) calculated from transient subcritical experiments by using TRACY made a line with a slope indicated by the new equation.
Subekti, M.*; Kudo, Kazuhiko*; Nabeshima, Kunihiko; Takamatsu, Kuniyoshi
Atom Indonesia, 43(2), p.93 - 102, 2017/08
Reactor kinetics based on point kinetic model have been generally applied as the standard method for neutronics codes. As the central control rod (C-CR) withdrawal test has demonstrated in a prismatic core of HTTR, the transient calculation of kinetic parameter, such as reactivity and neutron fluxes, requires a new method to shorten calculation-process time. Development of neural network method was applied to point kinetic model as the necessity of real-time calculation that could work in parallel with the digital reactivity meter. The combination of TDNN and Jordan RNN, such as TD-Jordan RNN, was the result of the modeling approach. The application of TD-Jordan RNN with adequate learning, tested offline, determined results accurately even when signal inputs were noisy. Furthermore, the preprocessing for neural network input utilized noise reduction as one of the equations to transform two of twelve time-delayed inputs into power corrected inputs.
Takamatsu, Kuniyoshi; Tochio, Daisuke; Nakagawa, Shigeaki; Takada, Shoji; Yan, X.; Sawa, Kazuhiro; Sakaba, Nariaki; Kunitomi, Kazuhiko
Journal of Nuclear Science and Technology, 51(11-12), p.1427 - 1443, 2014/11
Times Cited Count:15 Percentile:72.47(Nuclear Science & Technology)In a safety demonstration test involving a loss of both reactor reactivity control and core cooling, HTGRs such as the HTTR, which is the only HTGR in Japan, demonstrate that the reactor power would stabilize spontaneously. In the test at an initial power of 30%, when the insertion of all control rods was disabled and all gas circulators were tripped to reduce the coolant flow rate to zero, a reactor transient was initiated and examined. The results confirmed that the reactor power would decrease immediately and become effectively zero.
Shibata, Yasushi*; Matsumura, Akira*; Yamamoto, Tetsuya*; Akutsu, Hiroyoshi*; Yasuda, Susumu*; Nakai, Kei*; Nose, Tadao*; Yamamoto, Kazuyoshi; Kumada, Hiroaki; Hori, Naohiko; et al.
Research and Development in Neutron Capture Therapy, p.1055 - 1060, 2002/09
We prospectively investigated the predictability of blood boron concentrations using the data obtained at the first craniotomy after infusion of a low dose of sodium undecahydroclosododecaborate (BSH). Nine patients with malignant glial tumors underwent Boron neutron capture therapy (BNCT) at the Japan Atomic Energy Research Institute (JAERI) between 1995 and 2001. In 7 patients, 1g of BSH was infused before the first tumor removal and boron concentrations were determined using prompt gamma ray analysis (PGA). Then, 12 hours before BNCT, patients were infused at a dose of 100mg/kg BSH, and the boron concentrations were determined again. The boron biodistribution data showed a biexponential pharmacokinetic profile. If the final boron concentration at 6 or 9 hours after the end of the infusion is within the 95% confidence interval of the prediction, direct prediction from biexponential fit will reduce the error of blood boron concentrations during irradiation to around 6%.
Shimakawa, Satoshi; Tabata, Toshio; Komukai, Bunsaku
JAERI-Data/Code 99-045, p.31 - 0, 1999/11
no abstracts in English
Yamane, Tsuyoshi; Takeuchi, Mitsuo; Shimakawa, Satoshi; Kaneko, Yoshihiko*
Nihon Genshiryoku Gakkai-Shi, 40(2), p.122 - 123, 1998/00
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)no abstracts in English
G.D.Spriggs*; R.D.Busch*; Sakurai, Takeshi; Okajima, Shigeaki
Transactions of the American Nuclear Society, 76, p.374 - 375, 1997/06
no abstracts in English
Kaneko, Yoshihiko*; Yamane, Tsuyoshi; Shimakawa, Satoshi; Yamashita, Kiyonobu
Nihon Genshiryoku Gakkai-Shi, 38(11), p.907 - 911, 1996/00
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)no abstracts in English
Nagaya, Yasunobu;
Annals of Nuclear Energy, 22(7), p.421 - 440, 1995/00
Times Cited Count:9 Percentile:65.95(Nuclear Science & Technology)no abstracts in English
Murao, Yoshio; Araya, Fumimasa; Iwamura, Takamichi; Watanabe, Hironori
Transactions of the American Nuclear Society, 69, p.539 - 540, 1993/00
no abstracts in English
Araya, Fumimasa; Hirano, Masashi; ; Matsumoto, Kiyoshi; Yokobayashi, Masao; Kosaka, Atsuo
Nihon Genshiryoku Gakkai-Shi, 34(9), p.879 - 888, 1992/09
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)no abstracts in English
Araya, Fumimasa;
JAERI-M 91-071, 53 Pages, 1991/05
no abstracts in English
; Inabe, Teruo
JAERI-M 84-203, 67 Pages, 1984/11
no abstracts in English
Onishi, Nobuaki; Inabe, Teruo
Journal of Nuclear Science and Technology, 19(7), p.528 - 542, 1982/00
Times Cited Count:10 Percentile:71.00(Nuclear Science & Technology)no abstracts in English