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Takaya, Shigeru; Seki, Akiyuki; Yoshikawa, Masanori; Sasaki, Naoto*; Yan, X.
Mechanical Engineering Journal (Internet), 11(2), p.23-00408_1 - 23-00408_11, 2024/04
Enhancing the ability to manage abnormal situations is important for improvement of the safety of nuclear power plants. It is necessary to investigate potential risks thoroughly in advance, and prepare countermeasures against the identified risks. In case of an occurrence of an abnormal situation, plant operators are required to recognize the plant situation promptly and select a suitable countermeasure. This study develops a novel plant operator support system designed not only to estimate details of anomalies in a plant but also propose countermeasures adaptively by employing several AI technologies of deep neural network and reinforcement learning. The design and performance of the proposed system is illustrated using High Temperature engineering Test Reactor operated in Japan Atomic Energy Agency.
Nishimura, Shoichiro*; Torii, Hiroyuki*; Fukao, Yoshinori*; Ito, Takashi; Iwasaki, Masahiko*; Kanda, Sotaro*; Kawagoe, Kiyotomo*; Kawall, D.*; Kawamura, Naritoshi*; Kurosawa, Noriyuki*; et al.
Physical Review A, 104(2), p.L020801_1 - L020801_6, 2021/08
Times Cited Count:16 Percentile:82.28(Optics)Takaya, Shigeru; Sasaki, Naoto*
Mechanical Engineering Journal (Internet), 7(3), p.19-00549_1 - 19-00549_9, 2020/06
Seismic buckling of vessels is one of main concerns for the design of fast reactor plants in Japan. In previous studies, we discussed evaluation methods of seismic buckling probability of vessels by taking account of seismic hazards in order to rationalize seismic buckling evaluation, and proposed a rule for seismic buckling of vessels based on the load and resistant factor design method. The proposed method deals with only seismic load, but in actuality, dead weight and internal pressure also exist. In this study, the rule was expanded so that dead weight and internal pressure can be taken into account. Furthermore, the influences of dead weight and internal pressure to seismic buckling evaluation were discussed. As result, it was shown that approximately 10 to 20% of further rationalization of allowable seismic load could be achieved by considering dead weight and internal pressure in the evaluation.
Ueno, Yasuhiro*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Katsuhiko*; Ito, Takashi; Iwasaki, Masahiko*; et al.
Hyperfine Interactions, 238(1), p.14_1 - 14_6, 2017/11
Times Cited Count:3 Percentile:85.06(Physics, Atomic, Molecular & Chemical)Takaya, Shigeru; Sasaki, Naoto*; Asayama, Tai; Kamishima, Yoshio*
Mechanical Engineering Journal (Internet), 4(3), p.16-00558_1 - 16-00558_12, 2017/06
In this study, we developed a new design rule for the prevention of seismic buckling of vessels using the load and resistance factor design method to enable more rational vessel designs. The effectiveness of the new design rule was illustrated in comparison with the current provision.
Strasser, P.*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Katsuhiko*; Ito, Takashi; Iwasaki, Masahiko*; et al.
Hyperfine Interactions, 237(1), p.124_1 - 124_9, 2016/12
Times Cited Count:7 Percentile:89.76(Physics, Atomic, Molecular & Chemical)Takaya, Shigeru; Sasaki, Naoto*; Tomobe, Masato*
JAEA-Data/Code 2015-002, 54 Pages, 2015/03
Many efforts have been made to implement the System Based Code concept of which objective is to optimize margins dispersed in several codes and standards. Failure probability is expected to be a promising quantitative index for optimization of margins, and statistical information for random variables is needed to evaluate failure probability. Statistical information of material strength has not been provided enough yet. In this report, the statistical properties of material strength was estimated for SUS304, 316FR steel and some other austenitic stainless steels. These materials are registered in the JSME code of design and construction of fast reactors, so test data used for developing the code were used as much as possible in this report.
Sakakibara, Tetsuro; Aoyama, Yoshio; Yamaguchi, Hiromi; Sasaki, Naoto*; Nishikawa, Takeshi*; Murata, Minoru*; Park, J.*; Taniguchi, Shoji*; Fujita, Michiru*; Fukuda, Tomoyuki*; et al.
Proceedings of International Waste Management Symposium 2009 (WM '09) (CD-ROM), 15 Pages, 2009/03
The volume reduction treatment of solid waste system by ultra-high frequency induction furnace (UHFIF) was developed from FY2005 to FY2007. Basic data for melting performance were collected by non-radioactive experiments using the bench scale UHFIF with a crucible capacity of 10 liters. Based on the obtained data, engineering specifications were evaluated for a demonstration scale UHFIF with a crucible capacity of 30 liters. A new demonstration scale UHFIF was constructed and melting experiments of surrogate wastes were carried out by this furnace. It was confirmed that the demonstration scale UHFIF can melt ferrous metal, ceramics and aluminum all together and stabilize aluminum by oxidation to alumina. Density, chemical composition, and surface condition of the solidified substances were analyzed, and homogeneity of the solidified substances was confirmed. Melting behavior in the demonstration scale UHFIF was analyzed by computer simulation and simulation results agreed well with the experimental ones. From the design study for a full scale UHFIF with a crucible capacity of 100 liters, basic specifications were evaluated for the full scale UHFIF. Based on the obtained specification, melting behavior in the full scale UHFIF was analyzed by computer simulation.
Kirihara, Kazuhiro*; Kawaguchi, Kenji*; Shimizu, Yoshiki*; Sasaki, Takeshi*; Koshizaki, Naoto*; Kimura, Kaoru*; Yamada, Yoichi; Yamamoto, Hiroyuki; Shamoto, Shinichi
no journal, ,
Radiation effects of the boron nano-belt on the electronic conductivity have been studied.
Aoyama, Yoshio; Sakakibara, Tetsuro; Yamaguchi, Hiromi; Sasaki, Naoto*; Taniguchi, Shoji*; Fujita, Michiru*; Suzuki, Hiroshi*
no journal, ,
no abstracts in English
Sasaki, Toshihiko*; Kobayashi, Yuichi*; Morii, Yukio; Metoki, Naoto; Hirose, Yukio*
no journal, ,
no abstracts in English
Takaya, Shigeru; Sasaki, Naoto*; Okamoto, Toshiki*; Machida, Hideo*
no journal, ,
This paper describes benchmark analysis of independently programmed structural reliability evaluation codes, REAL-P and GENPEP. An upper core structure was chosen, and crack initiation time due to fatigue-creep interaction damage was evaluated in deterministic and probabilistic manners. Evaluation procedures follows new guidelines issued by JSME. The results estimated by two codes agreed very well for both deterministic and probabilistic evaluations, which indicates that these codes are programmed properly according to the guidelines.
Kirihara, Kazuhiro*; Kawaguchi, Kenji*; Shimizu, Yoshiki*; Sasaki, Takeshi*; Koshizaki, Naoto*; Kimura, Kaoru*; Yamada, Yoichi; Yamamoto, Hiroyuki; Shamoto, Shinichi
no journal, ,
Isotopic B atom has large thermal neutron capture cross section.
Li atom and
particle as a product of the neutron reaction can change the electrical transport property of the boron-rich semiconductor because they provide carrier doping and lattice defects. We successfully synthesized catalyst-free single-crystalline boron nanobelts (BNBs) and clarified the electrical transport and photoconduction mechanism of individual nanobelt. The BNB device is promising candidates for solid-state neutron sensors with both high resolution and good discrimination performance between neutron and
-ray. In the presentation, we discuss the performance of thermal neutron detection of BNB devices. Isotopic
B enriched BNBs was synthesized to detect thermal neutrons efficiently. Electrical conductance of a nanobelt increased to eight times after the thermal neutron irradiation with a dose of 1.8
10
cm
by the neutron reaction of
B.
Kirihara, Kazuhiro*; Kawaguchi, Kenji*; Shimizu, Yoshiki*; Sasaki, Takeshi*; Koshizaki, Naoto*; Kimura, Kaoru*; Yamada, Yoichi; Yamamoto, Hiroyuki; Shamoto, Shinichi
no journal, ,
We discuss the effects of neutron and -ray irradiation on electrical transport of single-crystalline boron nanobelts toward a nano-scale radiation sensor device. Changes of electrical conductance of individual nanobelt before and after thermal neutron irradiation with low (10
cm
s
) or high (3
10
cm
s
) flux are presented.
Aoyama, Yoshio; Sakakibara, Tetsuro; Yamashita, Toshiyuki; Sasaki, Naoto*; Nishikawa, Takeshi*
no journal, ,
no abstracts in English
Sasaki, Shigemi*; Miyamoto, Atsushi*; Hosaka, Masahito*; Yamamoto, Naoto*; Kyo, Ayataro*; Kato, Masahiro*; Imazono, Takashi; Koike, Masato
no journal, ,
The phenomenon of higher harmonic radiation from a helical undulator carrying orbital angular momentum (OAM) attracts a great deal of attention because this novel property may be used as a new probe for synchrotron radiation science that would be performed in diffraction limited light source facilities. Although a diffraction limited VUV and X-ray sources do not yet exist, the 750 MeV UVSOR-III is already a diffraction limited light source in the UV region. In this ring, a tandem-aligned double-APPLE undulator system is installed. Using this set-up, we observed spiral interference patterns between two different harmonic radiations with a scanning fiber multi-channel spectrometer and a CCD camera placed at the end of BL1U beamline. By these measurements, various interference patterns such as single, double, and triple spirals were observed which concur with the theoretical prediction for every mode in the right or left circular polarization.