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Watanabe, Seiya*; Kawahara, Jun*; Aoki, Takayuki*; Sugihara, Kenta; Takase, Shinsuke*; Moriguchi, Shuji*; Hashimoto, Hirotada*
Engineering Applications of Computational Fluid Mechanics, 17(1), p.2211143_1 - 2211143_23, 2023/00
Times Cited Count：1 Percentile：61.52(Engineering, Multidisciplinary)In tsunami inundations or slope disasters of heavy rain, a lot of floating debris or driftwood logs are included in the flows. The damage to structures from solid body impacts is more severe than the damage from the water pressure. In order to study free-surface flows that include floating debris, developing a high-accurate simulation code of free-surface flows with high performance for large-scale computations is desired. We propose the single-phase free-surface flow model based on the cumulant lattice Boltzmann method coupled with a particle-based rigid body simulation. The discrete element method calculates the contact interaction between solids. An octree-based AMR (Adaptive Mesh Refinement) method is introduced to improve computational accuracy and time-to-solution. High-resolution grids are assigned near the free surfaces and solid boundaries. We conducted two kinds of tsunami flow experiments in the 15 and 70 m water tanks at Hachinohe Institute of Technology and Kobe University to validate the accuracy of the proposed model. The simulation results have shown good agreement with the experiments for the drifting speed, the number of trapped wood pieces, and the stacked angles.
Yamamoto, Tomohiko; Kato, Atsushi; Chikazawa, Yoshitaka; Hara, Hiroyuki*
Nuclear Technology, 206(12), p.1875 - 1890, 2020/12
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)This paper gives a detailed evaluation of the countermeasures for the external hazards and severe accidents that could impact the 2010 JSFR design building by lessons learned from the Fukushima Daiichi Nuclear Power Plant (Fukushima I NPP) accident.
Choi, B.; Nishida, Akemi; Itoi, Tatsuya*; Takada, Tsuyoshi*
Geosciences (Internet), 8(1), p.1_1 - 1_22, 2018/01
After the Tohoku earthquake in 2011, we observed that aftershocks tended to occur in a wide region after such a large earthquake. These aftershocks resulted in secondary damage or delayed rescue and recovery activities. However, it is difficult to evaluate the hazards of an aftershock before the main shock due to various uncertainties. For possible great earthquakes, we must make decisions based on such uncertainties, and it is important to quantify the various uncertainties. We previously proposed a probabilistic aftershock occurrence model that is expected to be useful to develop plans for recovery activities after future large earthquakes. In this paper, engineering applications of the proposed approach for probabilistic aftershock hazard analysis are shown for demonstration purposes. One application is to use aftershock hazard maps to plan recovery activities. Another application is to derive load combination equations of the load and resistance factor design (LRFD) considering the simultaneous occurrence of tsunamis and aftershocks for the tsunami-resistant design of tsunami evacuation buildings and nuclear facilities.
Kaminaga, Masanori; Kusunoki, Tsuyoshi; Araki, Masanori
no journal, ,
The Japan Materials Testing Reactor (JMTR) is a light water cooled and moderated tank type research reactor with 50MW thermal power. From its first criticality in March 1968, the JMTR has been utilized for the fuel/material irradiation examinations of the LWRs, the HTGR and nuclear fusion research as well as for the RI productions. The JMTR operation was once stopped in order to have a check & review in August 2006, and the refurbishment and restart of the JMTR was finally determined after the national discussion. The refurbishment was started from JFY 2007, and was finished in March 2011. However, at the end of the JFY 2010, the Great East Japan Earthquake occurred, and the functional tests before the JMTR restart were delayed. On the other hand, based on the safety assessments considering the Great East Japan Earthquake in 2011, new regulatory requirements for research and test reactors have been established on Dec.18, 2013 by the NRA (Nuclear Regulation Authority). The new regulatory requirements include the satisfaction of integrities for the updated earthquake forces, Tsunami, the consideration of natural phenomena, the provision of manuals for full evacuation, and the management of consideration in the Beyond Design Basis Accidents to protect fuel damage and to mitigate impact of the accidents. Above analyses have intensively been performed, and an application to the NRA was submitted on March 27, 2015. In this presentation, the recent activities for the new regulatory requirements and a training course for foreign young researchers and engineers are introduced.
