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Li, C.-Y.; Watanabe, Akira*; Uchibori, Akihiro; Okano, Yasushi
Journal of Nuclear Science and Technology, 61(7), p.935 - 957, 2024/07
Times Cited Count：2 Percentile：43.92(Nuclear Science & Technology)Ishida, Shinya; Uchibori, Akihiro; Okano, Yasushi
Dai-28-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (Internet), 4 Pages, 2024/06
no abstracts in English
Li, C.-Y.; Watanabe, Akira*; Uchibori, Akihiro; Okano, Yasushi
Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 10 Pages, 2023/05
Li, C.-Y.; Watanabe, Akira*; Uchibori, Akihiro; Okano, Yasushi
Dai-26-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (Internet), 4 Pages, 2022/07
Identifying accident scenarios that could lead to severe accidents and evaluating their frequency of occurrence are essential issues. This study aims to establish the methodology of the dynamic Probabilistic Risk Assessment (PRA) for sodium-cooled fast reactors that can consider the time dependency and the interdependence of each event. Specifically, the Continuous Markov chain Monte Carlo (CMMC) method is newly applied to the SPECTRA code, which analyzes the severe accident conditions of nuclear reactors, to develop an evaluation methodology for typical external hazards. Currently, a fault-tree model of air coolers of decay heat removal system is implemented as the CMMC method, and a series of preliminary analysis of the plant's transient characteristics under the scenario of volcanic ashfall has been conducted.
Li, C.-Y.; Uchibori, Akihiro; Takata, Takashi; Pellegrini, M.*; Erkan, N.*; Okamoto, Koji*
Dai-25-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (Internet), 4 Pages, 2021/07
The capability of stable cooling and avoiding re-criticality on the debris bed are the main issues for achieving IVR (In-Vessel Retention). In the actual situation, the debris bed is composed of mixed-density debris particles. Hence, when these mixed-density debris particles were launched to re-distribute, the debris bed would possibly form a density-stratified distribution. For the proper evaluation of this scenario, the multi-physics model of CFD-DEM-Monte-Carlo based neutronics is established to investigate the coolability and re-criticality on the heterogeneous density-stratified debris bed with considering the particle relocation. The CFD-DEM model has been verified by utilizing water injection experiments on the mixed-density particle bed in the first portion of this research. In the second portion, the coupled system of the CFD-DEM-Monte-Carlo based neutronics model is applied to reactor cases. Afterward, the debris particles' movement, debris particles' and coolant's temperature, and the k-eff eigenvalue are successfully tracked. Ultimately, the relocation and stratification effects on debris bed's coolability and re-criticality had been quantitatively confirmed.
Am reactor activation measurements
erovnik, G.*; Schillebeeckx, P.*; Becker, B.*; Fiorito, L.*; Harada, Hideo; Kopecky, S.*; Radulovic, V.*; Sano, Tadafumi*
Nuclear Instruments and Methods in Physics Research A, 877, p.300 - 313, 2018/01
Times Cited Count：5 Percentile：39.83(Instruments & Instrumentation)Methodologies to derive cross section data from spectrum integrated reaction rates were studied. The Westcott convention and some of its approximations were considered. The accuracy of the results strongly depends on the assumptions that are made about the neutron energy distribution, which is mostly parameterised as a sum of a thermal and an epi-thermal component. Resonance integrals derived from such data can be strongly biased. When the energy dependence of the cross section is known and information about the neutron energy distribution is available, a method to correct for a bias on the cross section at thermal energy is proposed. Reactor activation measurements to determine the thermal Am(n, 
) cross section reported in the literature were reviewed, where the results were corrected to account for possible biases. These data combined with results of time-of-flight measurements give a capture cross section 720 (14) b for Am(n, ) at thermal energy.
Hishinuma, Akimichi
Purazuma, Kaku Yugo Gakkai-Shi, 70(7), p.719 - 725, 1994/07
no abstracts in English
Suzuki, Masatoshi; ; Ichikawa, Hiroki
JAERI-M 92-201, 17 Pages, 1993/01
no abstracts in English
Naito, Yoshitaka; Furuta, Teruo; Ichikawa, Hiroki; Takano, Hideki
JAERI-M 91-028, 151 Pages, 1991/03
no abstracts in English
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JAERI-M 82-009, 43 Pages, 1982/03
no abstracts in English
Kaneko, Yoshihika; Iijima, Tsutomu; Mizuho, Mitsuru; Fuse, Takayoshi*; Fujita, Yoshiaki*; Nakazawa, Masaharu*; Sekiguchi, Akira*; Kimura, Itsuro*
Nihon Genshiryoku Gakkai-Shi, 18(2), p.77 - 88, 1976/02
no abstracts in English
