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Yamazaki, Takumi*; Hirai, Takamasa*; Yagi, Takashi*; Yamashita, Yuichiro*; Uchida, Kenichi*; Seki, Takeshi*; Takanashi, Koki
Physical Review Applied (Internet), 21(2), p.024039_1 - 024039_11, 2024/02
Times Cited Count：0Yamashita, Susumu; Sato, Takumi; Nagae, Yuji; Kurata, Masaki; Yoshida, Hiroyuki
Journal of Nuclear Science and Technology, 60(9), p.1029 - 1045, 2023/09
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)Yamashita, Takuya; Sato, Takumi; Madokoro, Hiroshi; Nagae, Yuji
Annals of Nuclear Energy, 173, p.109129_1 - 109129_15, 2022/08
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)Horiike, Takumi*; Dotsuta, Yuma*; Nakano, Yuriko*; Ochiai, Asumi*; Utsunomiya, Satoshi*; Onuki, Toshihiko; Yamashita, Mitsuo*
Applied and Environmental Microbiology, 83(20), p.e00855-17_1 - e00855-17_11, 2017/10
Times Cited Count：18 Percentile：58.91(Biotechnology & Applied Microbiology)Radioactive strontium (
Sr) leaked into the ocean from the Fukushima Daiichi Nuclear Power Plant after the nuclear accident. Since the removal of Sr using general adsorbents is not efficient at high salinity, this study investigated removal of soluble Sr from a saline solution by biogenic carbonate minerals. An isolate, Bacillus sp. strain TK2d, from marine sediment removed more than 99 % of Sr in a saline solution. Sr adsorbed at the cell surface and then carbonate minerals containing Sr developed outside the cells.
Yamashita, Yuji*; Saito, Takumi
Journal of Environmental Chemical Engineering, 3(4), p.3024 - 3029, 2015/12
Humic substances are natural organic matters with heterogeneity in the size distribution and composition of there functional groups. In this study, the effects of organic acid, which are often used as pH buffering agents, on the size of a humic substance and size-dependent binding of metal ions on the humic substance were investigated by flow-field flow fractionation (Fl-FFF). Comparing the three organic acids, Tris, MES, and MOPS, the size of purified Aldrich humic acid (PAHA) changed in the presence of Tris and MES, suggesting that the interaction with these organic acid modulated the molecular structure of PAHA; on the other hand, MOPS hardly affect the size of PAHA. Size-dependent binding of europium (Eu
) and uranium (UO
) were also studied by Fl-FFF in the presence of MOPS. The binding of these metal ions were not homogeneous with respect to the size of PAHA; they exhibited high affinity to PAHA fractions with 5 nm hydrodynamic diameter.
Sanda, Toshio; Yamashita, Takumi; Mizuno, Tomoyasu
Proceedings of International Conference on Nuclear Energy System for Future Generation and Global Sustainability (GLOBAL 2005) (CD-ROM), 6 Pages, 2005/10
A conceptual core design study is performed on Pb-Bi cooled fast reactor with forced circulation (FC) cooling in the Feasibility Study on Commercialized Fast Reactor Cycle System (FS) in Japan. From the viewpoint of Pb-Bi eutectic alloy application as reactor coolant, Pb-Bi/core material compatibility is one of the most significant issues. The previous core design study assumes that the maximum acceptable fuel pin cladding temperature is to be 650 deg-C and applies provisional cladding corrosion correlation based on a little available information of ferritic/martensitic steel-Pb(-Bi) compatibility studies. Recently new cladding corrosion correlation was proposed based on recent material corrosion tests in the Pb-Bi eutectic alloys, which suggests that the acceptable fuel pin cladding temperature is to be 570 deg-C. The core design is performed under the new corrosion conditions for 750MWe Pb-Bi cooled reactor. The designed core without upper axial and radial blanket achieves the target of the FS, such as 1.1 of breeding ratio and core average burnup of 150GWd/t, filling the demand from a plant design. And shielding structures around the core are set, shielding performance is checked.
Yamashita, Takumi; Sanda, Toshio; Mizuno, Tomoyasu
JNC TN9400 2005-039, 88 Pages, 2005/08
JNC-TN9400-2005-039.pdf:4.73MB
In "Feasibility Studies on Commercialized Fast Breeder Reactor Cycle System(FS)", various types of fast breeder reactor using different coolant have been studied, in which lead-bismuth is one of the subject. In this study, design studies of medium size forced circulation (FC) reactor were carried out using newly proposed correlation in evaluation for clad outside surface corrosion and in restriction on the maximum clad outside surface temperature to 570
C based on the design in JFY 2003. The influence of changes in foregoing design conditions on core performances of the FC reactor was smaller than that of natural circulation (NC) reactor, and consequently, design of the FC core (outputs were 1980MWt, 750MWe) was performed to meet demands for coolant velocity, bundle pressure loss and so on. The designed core was larger than that designed in JFY 2002 because of increase in fuel pin diameter and fuel pin pitch. The main specifications for the designed core were as follows; with no radial blanket, fuel pin diameter of 8.0mm, core height of 70cm, core equivalent diameter of 4.43m, envelope diameter of radial shielding region of 5.35m. The main core performances were as follows; operation period of 18 months, burn-up of over 150GWd/t, and breeding ratio of 1.10 for the breeding core and 1.04 for the break even core. They achieved the performance targets in the FS within the condition where envelope diameter of radial shielding region was less than 5.5m. Fast fluence was not restricted in anticipation of improvements on materials in the future. When it was restricted to the development target of ODS steel and PNC-FMS steel (5
10
n/cm
, E
0.1Mev), the burn-up was about 125GWd/t. From these results, prospect of possibility of core manufacture was gained within the new design conditions of clad corrosion and temperature.
Yamashita, Takumi; Sanda, Toshio; Mizuno, Tomoyasu
JNC TN9400 2004-065, 93 Pages, 2004/11
JNC-TN9400-2004-065.pdf:6.96MB
In "Feasibility Studies on Commercialized Fast Breeder Reactor Cycle System(FS)", various types of fast breeder reactor using different coolant are studied, in which lead-bismuth is one of the subject. In JFY 2003 study of FS phase-II, design studies of medium scale forced /natural circulation nitride fuel core (FC/NC core) were carried out considering DDI (duct-duct interaction) which was not considered in JFY 2001 studies. The prospect of satisfying a design target of the core performance was acquired by improved design. By comparing properties of FC core (750MWe) and NC core (550MWe), we recommended the FC core as a hopeful one to design. The FC core was superior to the NC core in the following points, (1)Larger average burn-up (core and blanket) (2)Less Pu-fissile loaded weight (3)Smaller core equivalent diameter in spite of larger generating power (4)The NC core has much problems from the viewpoint of earthquake-resistant design. A design target of high burn-up of 150 GWd/t was satisfied, but fast fluence on clad is over the development target of ODS steel and PNC-FMS stee1 (5 10n/cm, E0.1Mev). Cores in which fast fluence was restricted to less than the target were also designed. MOX fuel and metal fuel cores were studied, and the effect of composition of TRU fuel recovered from LWR to core performance was also investigated to show flexibility and diversity in the lead-bismuth cooled core. In recent studies, it is becoming clear that the present evaluation for the clad corrosion in lead-bismuth gives non-conservative result and lowering the highest clad temperature will be required in core design. The lowering of temperature was permissible according to preliminary analysis using the present corrosion correlation.
Konomura, Mamoru; Ogawa, Takashi; Okano, Yasushi; Yamaguchi, Hiroyuki; Murakami, Tsutomu; Takaki, Naoyuki; Nishiguchi, Youhei; Sugino, Kazuteru; Naganuma, Masayuki; Hishida, Masahiko; et al.
JNC TN9400 2004-035, 2071 Pages, 2004/06
JNC-TN9400-2004-035.pdf:76.42MB
The attractive concepts for Sodium-, lead-bismuth-, helium- and water-cooled FBRs have been created through using typical plant features and employing advanced technologies. Efforts on evaluating technological prospects of feasibility have been paid for these concepts. Also, it was comfirmed if these concepts satisfy design requierments of capability and performance presumed in the feasibilty study on commertialization of Fast Breeder Reactor Systems. As results, it was concluded that the selection of sodium-cooled reactor was most rational for practical use of FBR technologies in 2015.
Sato, Takumi; Nishi, Tsuyoshi*; Shirasu, Noriko; Kurata, Masaki; Yamashita, Yuichiro*
no journal, ,
no abstracts in English
Onuki, Toshihiko; Kozai, Naofumi; Sakamoto, Fuminori; Yu, Q.; Yamashita, Mitsuo*; Horiike, Takumi*; Utsunomiya, Satoshi*
no journal, ,
We have studied the elimination of Sr from sea water into biogenic calcite. Biogenic calcite were produced at 30 by a maline microbe of TK2d. SEM and TEM analyses showed that needle shaped precipitates containing Ca and Sr was formed when 1.0 mM Sr was added in the solution with TK2d strain. XAFS analysis indicates that coordination environment of Sr in the biotic coprecipitates differs from that in the abiotic one.
Sato, Takumi; Yamashita, Takuya; Madokoro, Hiroshi; Nagae, Yuji
no journal, ,
no abstracts in English
Sato, Takumi; Yamashita, Takuya; Shimomura, Kenta; Nagae, Yuji
no journal, ,
Sato, Takumi; Yamashita, Takuya; Shimomura, Kenta; Nagae, Yuji
no journal, ,
no abstracts in English
