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Shimada, Takahiro*; Otani, Akihito*; Iwamoto, Kosuke*; Kitamura, Seiji
Nihon Kikai Gakkai Rombunshu, C, 77(777), p.1661 - 1673, 2011/05
Three dimensional seismic isolation devices have been developed for the base isolation system of the Fast Breeder Reactor that is an advanced nuclear power buildings. The developed seismic isolation system consists of the hydraulic type vertical springs with rocking suppression mechanism and the laminated rubber bearings for horizontal direction. In this paper, it is reported the frictional characteristics on high hydraulic pressure condition from the experiments on the 1/2 size of real device and the results of the seismic simulation on the real size building with isolation-device that has those characteristics.
Tanaka, Tadao; Shimada, Taro; Ito, Takeshi*; Hirano, Takahiro*; Sukegawa, Takenori
Progress in Nuclear Science and Technology (Internet), 1, p.408 - 411, 2011/02
Nuclear power plant sites are allowed to be released from nuclear safety regulations after the plants are decommissioned in Japan. The regulatory compliance will require confirming that there is no significant radioactivity remaining on the sites for the site release. In the present study, we propose an evaluation method of Cs-137 remaining on sites of decommissioned nuclear power plants. The method is time-efficient and gives a conservative result. In the evaluation method concept, all of the Cs-137, which is in reality distributed across the area of interest, is assumed to be the single point source located at the furthest position on the surface of the area from a detector. For such a configuration, the counting time that the Cs-137 point source is detectable is predicted using Monte Carlo calculations. If radiation from the Cs-137 point source is not detected for longer than the predicted counting time, it can be proven that the radioactivity remaining on the surface of the area is lower than the radioactivity corresponding to the assumed Cs-137 point source. A Cs-137 radiation source was placed at a fixed distance from the Ge detector, and the peak counting rate of Cs-137 were measured. The detectable time predicted by Monte Carlo calculations was approximately equal to the actual measurement time by the Ge detector, which means that the proposed evaluation method was reasonable for the conservative evaluation of remaining radioactivity.
-spectrometry (Contract research)Maeda, Shingo*; Hirano, Takahiro*; Shimada, Taro; Nakayama, Shinichi
JAEA-Technology 2008-066, 35 Pages, 2008/10
JAEA-Technology-2008-066.pdf:4.83MB
Bulk in-situ -spectroscopy is effective for a slightly and uniformly contaminated surface such as a room surrounded by concrete walls. The time-consuming scoping scanning survey for the entire surface is essential to ensure the slight and uniform contamination prior to the bulk in-situ measurement. However, the scoping scanning survey is omissible if the conservative procedure is acceptable. The count rate, cps, for the material of interest can be obtained by in-situ Ge detector will be converted to the radioactivity using conversion factor, Bq/cps, which depends on the distance from the detector to the furthest point. The radioactive concentration, Bq/g, is evaluated by dividing the radioactivity by the "measurement unit" of 100 kg. This procedure could certainly produce a conservative value. If the value obtained by this procedure is lower than the regulated clearance level, the material of interest can be cleared without the prior scoping scanning survey.
Yamamoto, Tomohiko; Yan, X.; Shimada, Takahiro*; Motegi, Haruki*; Kai, Satoru*; Otani, Akihito*
no journal, ,
no abstracts in English
山本 智彦; Yan, X.
島田 貴弘*; 大谷 章仁*; 甲斐 聡流*
JP, 2020-095752 Patent licensing information Patent publication (In Japanese)
【課題】地震に対する浮体式構造物および搭載機器の励振を低減する。 【解決手段】浮体式免震システム100は、液体114を貯留する液体貯留部110と、液体114に浮揚して配置される浮体式構造物120と、液体114と接触する箇所に設けられ、気体134を収容する気体収容空間132と、を備え、液体114と気体134を含む流体中を伝播する地震波により応答する系の固有振動数に基づいて、気体収容空間132の体積が設定されている。
