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Yamano, Hidemasa; Okamura, Shigeki*
Transactions of the 26th International Conference on Structural Mechanics in Reactor Technology (SMiRT-26) (Internet), 9 Pages, 2022/07
Seismic response analyses were conducted for the pipe with and without the seismic isolation system based on the response waveforms. This study performed a fragility analysis by setting uncertainty parameters on the basis of existing studies. The comparison results showed that the seismic isolation technology is effective for the pipe to prevent cliff-edge effects. In other words, the seismic margin for the seismically isolated plant is 1.2 times larger than that of the non-isolated plant. To evaluate the response reduction effect, this study focused on response coefficients of components as uncertainty parameters, which were specified within a physically possible range. Even if the uncertainty is considered, the HCLPF for the isolated plant is nearly twice as high as the non-isolated plant, namely the response reduction effect is still significant for the isolated plant. Therefore, the isolation technology is effective to avoid cliff-edge effects.
Yamano, Hidemasa; Nishino, Hiroyuki; Kurisaka, Kenichi
Nuclear Engineering and Design, 308, p.86 - 95, 2016/11
Times Cited Count：7 Percentile：51.66(Nuclear Science & Technology)This paper describes snow probabilistic risk assessment (PRA) methodology development through external hazard and event sequence evaluations mainly in terms of decay heat removal (DHR) function of a sodium-cooled fast reactor (SFR). Using recent 50-year weather data at a typical Japanese SFR site, snow hazard categories were set for the combination of daily snowfall depth (snowfall speed) and snowfall duration which can be calculated by dividing the snow depth by the snowfall speed. For each snow hazard category, the event sequence was evaluated by event trees which consist of several headings representing the loss of DHR. Snow removal action and manual operation of the air cooler dampers were introduced into the event trees as accident managements. Access route failure probability model was also developed for the quantification of the event tree. In this paper, the snow PRA showed less than 10
/reactor-year of core damage frequency. The dominant snow hazard category was the combination of 1-2 m/day of snowfall speed and 0.5-0.75 day of snowfall duration. Importance and sensitivity analyses indicated a high risk contribution to secure the access routes.
Yamano, Hidemasa; Nishino, Hiroyuki; Kurisaka, Kenichi; Okano, Yasushi; Sakai, Takaaki; Yamamoto, Takahiro*; Ishizuka, Yoshihiro*; Geshi, Nobuo*; Furukawa, Ryuta*; Nanayama, Futoshi*; et al.
Proceedings of 2015 International Congress on Advances in Nuclear Power Plants (ICAPP 2015) (CD-ROM), p.454 - 465, 2015/05
This paper describes mainly strong wind PRA methodology development in addition to the project overview. In developing the strong wind PRA methodology, hazard curves were estimated by using Weibull and Gumbel distributions based on weather data recorded in Japan. The obtained hazard curves were divided into five discrete categories for event tree quantification. Next, failure probabilities for decay heat removal related components were calculated as a product of two probabilities: i.e., a probability for the missiles to enter the intake or outtake in the decay heat removal system, and fragility caused by the missile impacts. Finally, based on the event tree, the core damage frequency was estimated about 6
10
/year by multiplying the discrete hazard probabilities in the Gumbel distribution by the conditional decay heat removal failure probabilities. A dominant sequence was led by the assumption that the operators could not extinguish fuel tank fire caused by the missile impacts and the fire induced loss of the decay heat removal system.
Yamano, Hidemasa; Nishino, Hiroyuki; Kurisaka, Kenichi; Okano, Yasushi; Sakai, Takaaki; Yamamoto, Takahiro*; Ishizuka, Yoshihiro*; Geshi, Nobuo*; Furukawa, Ryuta*; Nanayama, Futoshi*; et al.
Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 10 Pages, 2015/05
This paper describes mainly snow margin assessment methodology development in addition to the project overview. For the snow margin assessment, the index is a combination of a snowfall rate and duration. Since snow removal can be expected during the snowfall, the developed snow margin assessment methodology is such that the margin was regarded as the snowfall duration up to the decay heat removal failure which was defined as when the snow removal rate was smaller than the snowfall rate.
Nojiri, Naoki; Shimakawa, Satoshi; Fujimoto, Nozomu; Goto, Minoru
Nuclear Engineering and Design, 233(1-3), p.283 - 290, 2004/10
Times Cited Count：12 Percentile：60.66(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.
Tokuda, Shinji
Proceedings of 30th EPS Conference on Controlled Fusion and Plasma Physics (CD-ROM), 4 Pages, 2003/00
When we solve the eigenvalue problem associated with the two-dimensional Newcomb equation, we can identify the stability of a tokamak plasma against ideal MHD perturbations. The eigenvalue problem does not give the physical growth rate when the plasma is unstable. However, we can determine the growth rate by constructing a dispersion relation that gives the relation between the growth rate and the eigenvalue. It is expected that the dispersion relation provides an effective and fast method of stability analysis of MHD modes close to the marginal stability against ideal MHD perturbations, and the relation can be extended for non-ideal MHD modes close to the marginal stability.
Maki, Koichi*; Konno, Chikara; Maekawa, Fujio; Maekawa, Hiroshi; ;
Fusion Technology, 36(1), p.52 - 61, 1999/07
no abstracts in English
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：0.00(Nuclear Science & Technology)no abstracts in English
Fujimoto, Nozomu; Takeuchi, Mitsuo; Fujisaki, Shingo; Nakano, Masaaki*; Yamashita, Kiyonobu; Mogi, Haruyoshi
UTNL-R-0378, p.5.1 - 5.10, 1999/00
no abstracts in English
Fujimoto, Nozomu; Nojiri, Naoki; Nakano, Masaaki*; Takeuchi, Mitsuo; Fujisaki, Shingo; Yamashita, Kiyonobu
JAERI-Tech 98-021, 66 Pages, 1998/06
no abstracts in English
; Nagashima, Keisuke; Ushigusa, Kenkichi; Kikuchi, Mitsuru
Fusion Engineering and Design, 38(4), p.417 - 428, 1998/00
Times Cited Count：5 Percentile：38.45(Nuclear Science & Technology)no abstracts in English
Tokuda, Shinji;
JAERI-Data/Code 97-040, 105 Pages, 1997/10
JAERI-Data-Code-97-040.pdf:2.32MB
no abstracts in English
Nagao, Yoshiharu; Shimakawa, Satoshi;
Transactions of the American Nuclear Society, 73, p.402 - 403, 1995/00
no abstracts in English
Murata, Isao; Shindo, Ryuichi; Shiozawa, Shusaku
Proc. of the 8th Int. Conf. on Radiation Shielding, p.365 - 370, 1994/00
no abstracts in English
Nagaoka, Yoshiharu; Saito, Minoru;
Transactions of the American Nuclear Society, 66, p.454 - 455, 1992/11
no abstracts in English
Journal of Physics; Condensed Matter, 3, p.7039 - 7046, 1991/00
Times Cited Count：4 Percentile：32.89(Physics, Condensed Matter)no abstracts in English
Soda, Kunihisa; Sugimoto, Jun; Yamano, N.; Shiba, Koreyuki
NUREG/CP-0118, p.12-7 - 12-8, 1991/00
no abstracts in English
Okuno, Hiroshi; Nomura, Yasushi
Proc. of the Int. Topical Meeting on Safety, Margins in Criticality Safety, p.48 - 53, 1989/00
no abstracts in English
; ; Saito, Hiroshi*;
JAERI-M 85-108, 24 Pages, 1985/08
no abstracts in English
Sudo, Yukio; ; ;
Journal of Nuclear Science and Technology, 22(7), p.551 - 564, 1985/00
Times Cited Count：21 Percentile：89.30(Nuclear Science & Technology)no abstracts in English
