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Oba, Yojiro; Motokawa, Ryuhei; Kaneko, Koji; Nagai, Takayuki; Tsuchikawa, Yusuke; Shinohara, Takenao; Parker, J. D.*; Okamoto, Yoshihiro
Scientific Reports (Internet), 13, p.10071_1 - 10071_8, 2023/06
Times Cited Count：1 Percentile：72.91(Multidisciplinary Sciences)Motokawa, Ryuhei; Kaneko, Koji; Oba, Yojiro; Nagai, Takayuki; Okamoto, Yoshihiro; Kobayashi, Taishi*; Kumada, Takayuki; Heller, W. T.*
Journal of Non-Crystalline Solids, 578, p.121352_1 - 121352_7, 2022/02
Times Cited Count：3 Percentile：22.84(Materials Science, Ceramics)Tsuji, Nobumasa*; Nakano, Masaaki*; Takada, Eiji*; Tokuhara, Kazumi*; Ohashi, Kazutaka*; Okamoto, Futoshi*; Tazawa, Yujiro; Inaba, Yoshitomo; Tachibana, Yukio
Proceedings of 6th International Topical Meeting on High Temperature Reactor Technology (HTR 2012) (USB Flash Drive), 9 Pages, 2012/10
Passive heat removal performance of the reactor vessel cavity cooling system (RCCS) is of primary concern for enhanced inherent safety of HTGR. In a loss of forced cooling accident, decay heat must be removed by radiation and natural convection of RCCS. Thus thermal hydraulic analysis of reactor internals and RCCS is powerful means for evaluation of the heat removal performance of RCCS. The thermal hydraulic analyses using CFD computation tools are conducted for normal operation of the High Temperature Engineering Test Reactor (HTTR) and are compared to the temperature distribution of measured data. The calculated temperatures on outer faces of the permanent side reflector (PSR) blocks are in fair agreement with measured data. The transient analysis for decay heat removal mode in HTTR is also conducted.
C high temperature gas-cooled reactorNakano, Masaaki*; Takada, Eiji*; Tsuji, Nobumasa*; Tokuhara, Kazumi*; Ohashi, Kazutaka*; Okamoto, Futoshi*; Tazawa, Yujiro; Tachibana, Yukio
Proceedings of 6th International Topical Meeting on High Temperature Reactor Technology (HTR 2012) (USB Flash Drive), 6 Pages, 2012/10
The conceptual core design study of High Temperature Gas-cooled Reactor (HTGR) is performed. The major specifications are 600 MW thermal output, 950C outlet coolant temperature, prismatic core type, enriched uranium fuel. The decay heat in the core can be removed with only passive measures, for example, natural convection reactor cavity cooling system (RCCS), even if any electricity is not supplied (station blackout). The transient thermal analysis of the depressurization accident in the case the primary coolant decreases to the atmosphere pressure shows that the fuels and the reactor pressure vessel temperatures are kept under their safety limit criteria. The fission product release, 
Ag and 
Cs from the fuels under the normal operation is small as to make maintenance of devices in the primary cooling system, such as a gas turbine, without remote maintenance. The HTGRs can achieve the advanced safety features based on their inherent passive safety characteristics.
Ohashi, Kazutaka; Nishihara, Tetsuo; Kunitomi, Kazuhiko; Nakano, Masaaki*; Tazawa, Yujiro*; Okamoto, Futoshi*
Nihon Genshiryoku Gakkai Wabun Rombunshi, 7(1), p.32 - 43, 2008/03
Interests on the development of the Very High-Temperature Gas-Cooled Reactor (VHTR), of which the reactor outlet temperature is 950C or much higher, are recently increasing world-widely and it was selected as one of the candidate reactor types of the GIF. Japan Atomic Energy Agency has already initiated R&D efforts on the electricity and hydrogen co-generation plant with VHTR system, GTHTR300C. Although technical feasibility of its VHTR reactor using Pin-in-block fuel, which has experience to be already used in the HTTR, has been shown fundamentally, more improvements of the core performances, such as decrease of the occupational exposure doses during the plant maintenance, are desired. This report presents the results of the conceptual core design study using Multi-hole type fuel and the study on the occupational exposure doses. The latter results shows much better plant maintainability compared to the previous results of the GTHTR-300.
Haruyama, Yasuyuki; Tachibana, Hiroyuki; Kojima, Takuji; *; Kashiwazaki, Shigeru*; *; *
Radioisotopes, 44(8), p.507 - 513, 1995/08
no abstracts in English
W.H.Chung*; Kojima, Takuji; *
Radioisotopes, 43(5), p.278 - 282, 1994/05
no abstracts in English
Haruyama, Yasuyuki; Kojima, Takuji; Tachibana, Hiroyuki; Agematsu, Takashi; Okamoto, Jiro; *
Radioisotopes, 42(8), p.445 - 451, 1993/08
no abstracts in English
Haruyama, Yasuyuki; Yotsumoto, Keiichi; Okamoto, Jiro
JAERI-M 93-114, 46 Pages, 1993/06
no abstracts in English
Kojima, Takuji; Haruyama, Yasuyuki; Tachibana, Hiroyuki; Tanaka, Ryuichi; Okamoto, Jiro; *; *
Applied Radiation and Isotopes, 44(1-2), p.361 - 365, 1993/00
Times Cited Count：5 Percentile：50.63(Chemistry, Inorganic & Nuclear)no abstracts in English
Sunaga, Hiromi; Tachibana, Hiroyuki; Tanaka, Ryuichi; Okamoto, Jiro; *; Saito, Toshio*
Radiation Physics and Chemistry, 42(4-6), p.749 - 752, 1993/00
Times Cited Count：3 Percentile：38.1(Chemistry, Physical)no abstracts in English
Kojima, Takuji; Tachibana, Hiroyuki; Haruyama, Yasuyuki; Tanaka, Ryuichi; Okamoto, Jiro
Radiation Physics and Chemistry, 42(4-6), p.813 - 816, 1993/00
Times Cited Count：8 Percentile：63.68(Chemistry, Physical)no abstracts in English
Kojima, Takuji; Haruyama, Yasuyuki; Tachibana, Hiroyuki; Tanaka, Ryuichi; Okamoto, Jiro; *; *; *; Kashiwazaki, Shigeru*
Radiation Physics and Chemistry, 42(4-6), p.757 - 760, 1993/00
Times Cited Count：7 Percentile：60.43(Chemistry, Physical)no abstracts in English
Okada, Sohei; Sunaga, Hiromi; Kaneko, Hirohisa; Tachibana, Hiroyuki; Yotsumoto, Keiichi; Okamoto, Jiro
Hoshasen, 18(2), p.63 - 81, 1992/05
no abstracts in English
Sunaga, Hiromi; Okada, Sohei; Kaneko, Hirohisa; Tachibana, Hiroyuki; Yotsumoto, Keiichi; Okamoto, Jiro
Proc. of the 17th Linear Accelerator Meeting in Japan, p.124 - 126, 1992/00
no abstracts in English
Sunaga, Hiromi; Okada, Sohei; Tachibana, Hiroyuki; Yotsumoto, Keiichi; Okamoto, Jiro
Proc. of the 16th LINEAR Accelerator Meeting in Japan, p.112 - 114, 1991/00
no abstracts in English
Okamoto, Jiro; Sugo, Takanobu; *; *
Radiation Physics and Chemistry, 35(1-3), p.113 - 116, 1990/00
no abstracts in English
Okamoto, Jiro
Kagaku Keizai, 1989(1), p.88 - 95, 1989/01
no abstracts in English
Sugo, Takanobu; Okamoto, Jiro
Nihon Kagakkai-Shi, 1988(9), p.1601 - 1606, 1988/09
no abstracts in English
Uezu, Kazuya*; Saito, Kyoichi*; Hori, Takahiro*; Furusaki, Shintaro*; Sugo, Takanobu; Okamoto, Joro
Nihon Genshiryoku Gakkai-Shi, 30(4), p.359 - 364, 1988/04
Times Cited Count：7 Percentile：61.33(Nuclear Science & Technology)no abstracts in English
