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Takata, Takashi; Azuma, Emiko*; Nishino, Hiroyuki; Yamano, Hidemasa; Sakai, Takaaki*
Proceedings of 10th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-10) (USB Flash Drive), 6 Pages, 2016/11
A new approach has been developed to assess event sequences under external hazard condition considering a plant status quantitatively and stochastically so as to take various scenarios into account automatically by applying a Continuous Markov Chain Monte Carlo (CMMC) method coupled with a plant dynamics analysis. In the paper, a strong wind is selected as the external hazard to assess the plant safety in a loop type sodium cooled fast reactor. As a result, it is demonstrated that the plant state is quite safe in case of the strong wind because multiple failures of the air coolers in the auxiliary cooling system (ACS) has a quite low probability. Furthermore, a weight factor is introduced so as to investigate the low failure probability events with a comparative small number of the sampling.
Yamano, Hidemasa; Nishino, Hiroyuki; Kurisaka, Kenichi; Okano, Yasushi; Sakai, Takaaki; Yamamoto, Takahiro*; Ishizuka, Yoshihiro*; Geshi, Nobuo*; Furukawa, Ryuta*; Nanayama, Futoshi*; et al.
Proceedings of 11th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, Operation and Safety (NUTHOS-11) (USB Flash Drive), 12 Pages, 2016/10
This paper describes mainly volcanic margin assessment methodology development in addition to the project overview. The volcanic tephra could potentially clog filters of air-intakes that need the decay heat removal. The filter clogging can be calculated by atmospheric concentration and fallout duration of the volcanic tephra and also suction flow rate of each component. In this paper, the margin was defined as a grace period to a filter failure limit. Consideration is needed only when the grace period is shorter than the fallout duration. The margin by component was calculated using the filter failure limit and the suction flow rate of each component. The margin by sequence was evaluated based on an event tree and the margin by component. An accident management strategy was also suggested to extend the margin; for instance, manual trip of the forced circulation operation, sequential operation of three air coolers, and covering with pre-filter.
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.
Yamano, Hidemasa; Nishino, Hiroyuki; Kurisaka, Kenichi; Okano, Yasushi; Sakai, Takaaki; Yamamoto, Takahiro*; Ishizuka, Yoshihiro*; Geshi, Nobuo*; Furukawa, Ryuta*; Nanayama, Futoshi*; et al.
Proceedings of 10th International Topical Meeting on Nuclear Thermal Hydraulics, Operation and Safety (NUTHOS-10) (USB Flash Drive), 12 Pages, 2014/12
This paper describes mainly snow probabilistic risk assessment (PRA) methodology development in addition to the project overview. In snow hazard category, the accident sequence was evaluated by producing event trees which consist of several headings representing the loss of decay heat removal. Snow removal action and manual operation of the air cooler dampers were introduced into the event tree as accident managements. The snow PRA showed less than 10
/reactor-year of core damage frequency.
IrSi
Pyon, S.*; Kudo, Kazutaka*; Matsumura, Junichi*; Ishii, Hiroyuki*; Matsuo, Genta*; Nohara, Minoru*; Hojo, Hajime*; Oka, Kengo*; Azuma, Masaki*; Garlea, V. O.*; et al.
Journal of the Physical Society of Japan, 83(9), p.093706_1 - 093706_5, 2014/09
Times Cited Count：33 Percentile：82.58(Physics, Multidisciplinary)Azuma, Hirozumi*; Sagisaka, Akito; Daido, Hiroyuki; Ito, Isao*; Kadoura, Hiroaki*; Kamiya, Nobuo*; Ito, Tadashi*; Nishimura, Akihiko; Ma, J.*; Mori, Michiaki; et al.
Applied Surface Science, 255(24), p.9783 - 9786, 2009/09
Times Cited Count：2 Percentile：11.71(Chemistry, Physical)Commercial single crystal silicon wafers and amorphous silicon films piled on single crystal silicon wafers were irradiated with a femtosecond pulsed laser and a nanosecond pulsed laser at irradiation intensities between 10
W/cm
and 10
W/cm. In the single crystal silicon substrate, the irradiated area was changed to polycrystalline silicon and the piled silicon around the irradiated area has spindly column structures constructed of polycrystalline and amorphous silicon. In particular, in the case of the higher irradiation intensity of 10
W/cm, the irradiated area was oriented to the same crystal direction as the substrate. In the case of the lower irradiation intensity of 10
W/cm, only amorphous silicon was observed around the irradiated area, even when the target was single crystal silicon.
Nishiuchi, Mamiko; Daido, Hiroyuki; Yogo, Akifumi; Orimo, Satoshi; Ogura, Koichi; Ma, J.-L.; Sagisaka, Akito; Mori, Michiaki; Pirozhkov, A. S.; Kiriyama, Hiromitsu; et al.
Physics of Plasmas, 15(5), p.053104_1 - 053104_10, 2008/05
Times Cited Count：45 Percentile：84.26(Physics, Fluids & Plasmas)High-flux energetic protons whose maximum energies are up to 4 MeV are generated by an intense femtosecond Titanium Sapphire laser pulse interacting with a 7.5, 12.5, and 25
m thick Polyimide tape targets. The laser pulse energy is 1.7 J, duration is 34 fs, and intensity is 310
Wcm
. The amplified spontaneous emission (ASE) has the intensity contrast ratio of 410
. The conversion efficiency from laser energy into proton kinetic energies of 
3% is achieved, which is comparable or even higher than those achieved in the previous works with nanometer-thick targets and the ultrahigh contrast laser pulses (10
).
Sagisaka, Akito; Azuma, Hirozumi*; Daido, Hiroyuki; Kamiya, Nobuo*; Ito, Tadashi*; Takeuchi, Akihiro*; Suzuki, Noritomo*; Nishimura, Akihiko; Mori, Michiaki; Orimo, Satoshi; et al.
Proceedings of 4th International Congress on Laser Advanced Materials Processing (LAMP 2006) (Internet), 3 Pages, 2006/00
no abstracts in English
Imai, Makoto*; Sataka, Masao; Kitazawa, Shinichi; Komaki, Kenichiro*; Kawatsura, Kiyoshi*; Shibata, Hiromi*; Tawara, Hiroyuki*; Azuma, Toshiyuki*; Kanai, Yasuyuki*; Yamazaki, Y.*
Nuclear Instruments and Methods in Physics Research B, 193(1-4), p.674 - 679, 2002/06
Times Cited Count：5 Percentile：34.51(Instruments & Instrumentation)no abstracts in English
Igarashi, Toru*; Ikeda, Kazutaka*; Azuma, Hiroyuki*; Imamura, Sugio*; Oshima, Masahiro*
JNC TJ1420 2001-035, 175 Pages, 2001/12
Kitazawa, Shinichi; Sataka, Masao; Tawara, Hiroyuki*; Imai, Makoto*; Shibata, Hiromi*; Komaki, Kenichiro*; Azuma, Toshiyuki*; Kawatsura, Kiyoshi*; Kanai, Yasuyuki*
Atomic Collision Research in Japan, No.25, p.65 - 67, 1999/00
no abstracts in English
Azuma, Hiroyuki*; Ando, Makoto*; Sakai, Ryutaro; Munakata, Masahiro; Kimura, Hideo
no journal, ,
In the safety assessment for a geological disposal of long-lived radioactive waste such as high-level radioactive waste it is important to develop the method evaluating of groundwater flow effect on the repository system. Japan Atomic Energy Agency has investigated more than 500 literatures to summarize 70 investigative techniques for effectiveness on the evaluation of geological and hydrological environment in the form of two-dimensional matrix table. As a result it demonstrates that electric prospecting techniques have been commonly used for evaluating of the groundwater flow system in the geophysical survey field in the past.
Nishiuchi, Mamiko; Daido, Hiroyuki; Yogo, Akifumi; Orimo, Satoshi; Ogura, Koichi; Ma, J.-L.; Sagisaka, Akito; Mori, Michiaki; Pirozhkov, A. S.; Kiriyama, Hiromitsu; et al.
no journal, ,
The efficient proton beam whose maximum energy of up to 4 MeV was produced by the 50TW short pulse intensity Ti:Sap laser irradiated on the polyimide target [(C
H
O
N
)n] with the thicknesses of 7.5m, 12.5m, 25m, which is transparent to the 800 nm laser. The laser parameters are energy of 1.7J, pulse width of 35fs and the intensity of 310 Wcm. The contrast of the ASE component is 410. The conversion efficiency from laser energy into the proton kinetic energy is up to 3%. This conversion efficiency is comparable or even higher than the results obtained with the same level laser ( J energy) interacts with the nano-meter level ultra thin target. In this paper we discuss on the comparison between our results and other experimental results obtained in other facilities.
Suzuki, Koichi*; Yoshimura, Kimitaka*; Sugita, Yutaka; Ando, Makoto*; Azuma, Hiroyuki*
no journal, ,
One of the benefits of geophysical exploration is that extensive and continuous surveys are possible at low cost, however, the obtained physical properties are chiefly velocity of elastic wave and electrical resistivity. Therefore, it is very important that the techniques can convert geophysical data into quantitative information on the geological environment required for engineering technology. In this study, we have applied an approach that provides estimates of porosity, clay content, and equivalent NaCl concentration based on a combined interpretation of geophysical survey data utilizing an expanded bimodal mixture model. The study used seismic velocity and electrical conductivity data obtained from geophysical logging at two soft sedimentary rock sites, in the muddy or tuffaceous sandstone and mudstone at Yokosuka, and in diatomaceous mudstone and fine sandstone at Horonobe, Japan. The geological information for these sites was successfully estimated.
Sumiya, Masato; Ikeda, Koki; Sonoda, Takashi; Niizato, Tadafumi; Mikake, Shinichiro; Abe, Hironobu; Inoue, Makoto; Eguchi, Kazutoshi; Kozawa, Masachiyo; Terunuma, Akihiro; et al.
no journal, ,
no abstracts in English
Yamano, Hidemasa; Nishino, Hiroyuki; Kurisaka, Kenichi; Okano, Yasushi; Sakai, Takaaki; Yamamoto, Takahiro*; Ishizuka, Yoshihiro*; Furukawa, Ryuta*; Geshi, Nobuo*; Nanayama, Futoshi*; et al.
no journal, ,
PRA and margin assessment methodologies are being developed for sodium-cooled fast reactors against representative external hazards. This report describes the overview of second-year (JPY2015) outcomes and the development of the margin assessment methodology against snow and tornado.
Yamano, Hidemasa; Nishino, Hiroyuki; Kurisaka, Kenichi; Okano, Yasushi; Sakai, Takaaki; Yamamoto, Takahiro*; Ishizuka, Yoshihiro*; Geshi, Nobuo*; Furukawa, Ryuta*; Nanayama, Futoshi*; et al.
no journal, ,
This paper describes mainly snow margin assessment methodology development in addition to the project overview. For the snow margin assessment, the index is the combination of a snowfall rate and duration. Since snow removal can be expected for the snowfall, this study developed the snow margin assessment methodology that the margin was regarded as the snowfall duration to the decay heat removal failure which was defined as when the snow removal rate was smaller than the snowfall rate.
Yamano, Hidemasa; Nishino, Hiroyuki; Kurisaka, Kenichi; Okano, Yasushi; Sakai, Takaaki; Yamamoto, Takahiro*; Ishizuka, Yoshihiro*; Furukawa, Ryuta*; Geshi, Nobuo*; Nanayama, Futoshi*; et al.
no journal, ,
PRA and margin assessment methodologies are being developed for sodium-cooled fast reactors against representative external hazards. This report describes the overview of Third-year (JPY2014) updates and the development of the sequence assessment methodology against volcanic eruption hazard.
Yamano, Hidemasa; Nishino, Hiroyuki; Okano, Yasushi; Kurisaka, Kenichi; Sakai, Takaaki; Yamamoto, Takahiro*; Ishizuka, Yoshihiro*; Furukawa, Ryuta*; Geshi, Nobuo*; Nanayama, Futoshi*; et al.
no journal, ,
A four-year research project since 2012 is being performed to develop risk assessment methodologies that include probabilistic risk assessment (PRA) and margin assessment methodologies against external hazards mainly for a sodium-cooled fast reactor. The present paper describes briefly the project overview and then mainly the development of PRA and margin assessment methodologies against strong wind. In this project, by 2014, PRA methodologies against snow, tornado, rain and strong wind were developed as well as their hazard evaluation methodologies. For a volcanic eruption hazard, tephra fallout simulations were carried out to contribute to the hazard evaluation methodology development. In developing the strong wind PRA methodology, hazard curves were estimated using the Gumbel distributions based on weather data recorded in Japan. Next, failure probabilities for components related to the decay heat removal function were calculated as a product of two probabilities: a probability for the missiles to enter the intake/outtake in the decay heat removal system, and fragility caused by the missile impacts. After developing event trees, a core damage frequency was estimated about 610/year by multiplying discrete hazard frequencies and conditional decay heat removal failure probabilities. The present study also developed the wind margin assessment methodology that the margin was regarded as wind speed leading to the decay heat removal failure.
