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Journal Articles

Development of effectiveness evaluations technology of the measures for improving resilience of nuclear structures at ultra high temperature

Onoda, Yuichi; Nishino, Hiroyuki; Kurisaka, Kenichi; Yamano, Hidemasa

Proceedings of Asian Symposium on Risk Assessment and Management 2021 (ASRAM 2021) (Internet), 11 Pages, 2021/10

The effectiveness evaluations technology of the measures for improving resilience by applying a fracture control concept under ultra-high temperature conditions has developed for prototype sodium-cooled fast reactor Monju as a model plant, and the trial evaluation has conducted using this technology in this paper. The important accident sequences to which the fracture control concept is expected to be applied under ultra-high temperature condition are identified by investigating the results of the existing researches of level-2 probabilistic risk assessment for Monju. Accident sequences categorized in protected loss of heat sink and loss of reactor level are both identified as such important accident sequences which has the potential to prevent core damage. This study has developed the technology to evaluate the effectiveness of improving resilience, where the headings which stand for success or failure of the measures to improve resilience are introduced into the event tree, the branch probability of them is set, and the effectiveness of improving resilience is expressed as the reduction of core damage frequency. As a result of the trial evaluation of the effectiveness for the measures to improve resilience, it is confirmed that core damage frequency can be reduced by applying fracture control concept. The branch probability of the measures to improve resilience proposed in this study is tentatively assigned based on the assumption. This value is expected to be quantified by the forthcoming analyses of the integrity for the reactor vessel structure at ultra-high temperature. The technology developed in this study will be applied for the evaluation of improving resilience of the next generation sodium-cooled fast reactor.

Journal Articles

Establishment of integrity evaluation method for Reserved Shutdown System of High-Temperature engineering Test Reactor (HTTR)

Hamamoto, Shimpei; Kawamoto, Taiki; Kondo, Makoto; Sawahata, Hiroaki; Takada, Shoji; Shinozaki, Masayuki

Nihon Genshiryoku Gakkai Wabun Rombunshi, 15(2), p.66 - 69, 2016/06

High Temperature engineering Test Reactor (HTTR) has the reactivity control system which is accompanied with the Reserved Shutdown System (RSS). The RSS consists of B$$_{4}$$C/C pellets, guide tube, electric plug, motor which contains brake and reducer, and so on. In accidents when the control rods cannot be inserted, an electric plug is pulled out by motor and the B$$_{4}$$C/C pellets fall into the core by gravity. It was revealed that the motor in the RSS drive mechanism did not work as the result of pre-start up checks as described followings: (1) The oil which was separated from a grease of motor reducer flowed down from gap of oil seal, (2) the separated oil penetrated into the brake, (3) the penetrated oil was mixed with abrasion powder released from brake disk, finally, (4) the adhesive mixture blocked the rotation of the motor. A new evaluation method was proposed to detect a sign of the motor sticking. Through the overhaul inspection of all RSS drive mechanisms of HTTR, it was revealed that the proposed method was effective to evaluate the integrity of the RSS drive mechanism.

Journal Articles

Reactivity control system of the high temperature engineering test reactor

Tachibana, Yukio; Sawahata, Hiroaki; Iyoku, Tatsuo; Nakazawa, Toshio

Nuclear Engineering and Design, 233(1-3), p.89 - 101, 2004/10

 Times Cited Count:8 Percentile:50.96(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Characteristic test of initial HTTR core

Nojiri, Naoki; Shimakawa, Satoshi; Fujimoto, Nozomu; Goto, Minoru

Nuclear Engineering and Design, 233(1-3), p.283 - 290, 2004/10

 Times Cited Count:11 Percentile:61.05(Nuclear Science & Technology)

This paper describes the results of core physics test in start-up and power-up of the HTTR. The tests were conducted in order to ensure performance and safety of the high temperature gas cooled reactor, and was carried out to measure the critical approach, the excess reactivity, the shutdown margin, the control rod worth, the reactivity coefficient, the neutron flux distribution and the power distribution. The expected core performance and the required reactor safety characteristics were verified from the results of measurements and calculations.

JAEA Reports

Investigation of automatic shutdown of HTTR on May 21st, 2003

Hirato, Yoji; Saito, Kenji; Kondo, Makoto; Sawahata, Hiroaki; Motegi, Toshihiro; Tsuchiyama, Masaru*; Ando, Toshio*; Mizushima, Toshihiko; Nakazawa, Toshio

JAERI-Tech 2004-037, 33 Pages, 2004/04

JAERI-Tech-2004-037.pdf:4.08MB

HTTR (High Temperature Engineering Test Reactor) was operated from May 6th, 2003 to June 18th, 2003 to obtain operation data in parallel loaded operation mode and in safety demonstration tests. Operated with the reactor power at 60% of the rated power on May 21st, HTTR was automatically scrammed by a signalof "Primary coolant flow rate of the Primary Pressurized Water Cooler (PPWC): Low". The cause of the shutdown was the primary gas circulator (A) automatically stopped. The primary coolant flow rate of the PPWC decresed and reached the scram set value due to the gas circulator stop. As a result of investigation, it became clear that the cause of the gas circulator stop was malfunction of an auxiliary relay which monitored electric power of a circuit breaker in power line of the gas circulator. The cause of malfunction was deterioration of the relay under high temperature condition because the relay was installed beside an electric part which was heated up by electricity.

JAEA Reports

Findings of the reactor automatic shutdown caused by a signal of a primary coolant flow rate of the PPWC:Low in the HTTR

Takamatsu, Kuniyoshi; Nakazawa, Toshio; Furusawa, Takayuki; Homma, Fumitaka; Saito, Kenji; Kokusen, Shigeru; Kamata, Takashi; Ota, Yukimaru; Ishii, Yoshiki; Emori, Koichi

JAERI-Tech 2003-062, 94 Pages, 2003/06

JAERI-Tech-2003-062.pdf:26.47MB

no abstracts in English

Journal Articles

Approach for safety assurance and structural integrity of ITER

Tada, Eisuke; Hada, Kazuhiko; Maruo, Takeshi; Safety Design/Evaluation Group

Purazuma, Kaku Yugo Gakkai-Shi, 78(11), p.1145 - 1156, 2002/11

no abstracts in English

Journal Articles

Safety shutdown of the High Temperature Engineering Test Reactor during loss of off-site electric power simulation test

Takeda, Takeshi; Nakagawa, Shigeaki; Homma, Fumitaka*; Takada, Eiji*; Fujimoto, Nozomu

Journal of Nuclear Science and Technology, 39(9), p.986 - 995, 2002/09

 Times Cited Count:4 Percentile:30.46(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Fast thermal shutdown of tokamak discharges without runaway electron avalanching

Bakhtiari, M.; Yoshino, Ryuji; Nishida, Yasushi*

Fusion Science and Technology, 41(2), p.77 - 87, 2002/03

 Times Cited Count:6 Percentile:41.16(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Neutronics analysis of the ITER NB system; Nuclear responses of the components and shutdown dose around the NB injector

Shibata, Keiichiro*; Maki, Koichi*; Inoue, Takashi*; Hanada, Masaya; Okumura, Yoshikazu; Yamashita, Y.*

Fusion Engineering and Design, 51-52, p.357 - 362, 2000/11

 Times Cited Count:1 Percentile:12.53(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Measurement of control rod reactivity worth with long insertion time by inverse kinetics rod drop method

Yamashita, Kiyonobu; Takeuchi, Mitsuo; Fujimoto, Nozomu; Fujisaki, Shingo; Nakano, Masaaki*; Nojiri, Naoki; Tamura, Seiji*

Nihon Genshiryoku Gakkai-Shi, 41(1), p.35 - 38, 1999/00

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

no abstracts in English

JAEA Reports

Preliminary analyses for HTTR's start-up physics tests by HTTR nuclear characteristics evaluation code system

Fujimoto, Nozomu; Nojiri, Naoki; Nakano, Masaaki*; Takeuchi, Mitsuo; Fujisaki, Shingo; Yamashita, Kiyonobu

JAERI-Tech 98-021, 66 Pages, 1998/06

JAERI-Tech-98-021.pdf:2.63MB

no abstracts in English

Journal Articles

Fast plasma shutdown by killer pellet injection in JT-60U with reduced heat flux on the divertor plate and avoiding runaway electron generation

Yoshino, Ryuji; Kondoh, Takashi; Neyatani, Yuzuru; Itami, Kiyoshi; Kawano, Yasunori; Isei, Nobuaki

Plasma Physics and Controlled Fusion, 39(2), p.313 - 332, 1997/02

 Times Cited Count:97 Percentile:93.71(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Benchmark calculation of JMTRC core with MCNP

Nagao, Yoshiharu; Shimakawa, Satoshi;

Transactions of the American Nuclear Society, 73, p.402 - 403, 1995/00

no abstracts in English

Journal Articles

Softening of Current quenches in JT-60U

Yoshino, Ryuji; Neyatani, Yuzuru; Hosogane, Nobuyuki; S.W.Wolfe*; Matsukawa, Makoto; Ninomiya, Hiromasa

Nuclear Fusion, 33(11), p.1599 - 1612, 1993/00

 Times Cited Count:33 Percentile:72.19(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Neutronics properties of JMTR LEU core

Nagaoka, Yoshiharu; Saito, Minoru;

Transactions of the American Nuclear Society, 66, p.454 - 455, 1992/11

no abstracts in English

JAEA Reports

A Feasibility study on the innovative control rod driving mechanism, 1

Ishizaka, Yuichi*;

JAERI-M 89-174, 105 Pages, 1989/11

JAERI-M-89-174.pdf:9.76MB

no abstracts in English

Journal Articles

Probabilistic method for evaluating reactivity margin of nuclear reactors

Journal of Nuclear Science and Technology, 21(4), p.308 - 314, 1984/00

 Times Cited Count:2 Percentile:30.46(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Fusion reactor shield optimization in terms of personnel access

; ; *

Journal of Nuclear Science and Technology, 19(1), p.11 - 19, 1982/00

 Times Cited Count:1 Percentile:22.14(Nuclear Science & Technology)

no abstracts in English

25 (Records 1-20 displayed on this page)