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Tc solution from 
Mo to be obtained by (
) reaction; A Preliminary study using inactive Re instead of TcTanase, Masakazu*; Fujisaki, Saburo*; Ota, Akio*; Shiina, Takayuki*; Yamabayashi, Hisamichi*; Takeuchi, Nobuhiro*; Tsuchiya, Kunihiko; Kimura, Akihiro; Suzuki, Yoshitaka; Ishida, Takuya; et al.
Radioisotopes, 65(5), p.237 - 245, 2016/05
no abstracts in English
Sekine, Yurina; Kobayashi, Riki*; Chi, S.*; Fernandez-Baca, J. A.*; Suzuya, Kentaro; Fujisaki, Fumika*; Ikeda, Kazutaka*; Otomo, Toshiya*; Fukazawa, Tomoko*; Yamauchi, Hiroki; et al.
JPS Conference Proceedings (Internet), 8, p.033009_1 - 033009_6, 2015/09
Neutron diffraction profiles of low-D
O-content poly-N,N,-dimethylacrylamide (PDMAA) hydrogels were measured from 100 to 300 K to investigate the structure and properties of water in hydrogels. A broad diffraction observed at temperatures lower than 220 K indicates the existence of amorphous ice in the hydrogels at low temperatures. During the heating process, diffraction peaks from ice crystals appear in the profiles. These peaks indicate that cubic ice and hexagonal ice exist at T 
220 K. We refined the structure parameters of these ices in the hydrogel, which indicate the existence of low-density ice in the hydrogel.
short elbow piping systems of JSFRTanaka, Masaaki; Fujisaki, Tatsuya*; Oki, Hiroshi*
Nihon Kikai Gakkai Kanto Shibu Ibaraki Koenkai 2013 Koen Rombunshu, p.141 - 142, 2013/09
Numerical simulation method to analyze unsteady flow phenomena in the upper plenum and the hot-leg piping system in Japan Sodium cooled Fast Reactor (JSFR) has been developed. A flow-induced vibration in the hot-leg piping is mainly targeted in this study. A numerical model of the hot-leg piping integrated into a full domain of the upper plenum was constructed. By comparing with the existing experimental results, applicability of numerical model was confirmed.
Fujisaki, Hiroshi*; Shiga, Motoyuki; Moritsugu, Kei*; Kidera, Akinori*
Journal of Chemical Physics, 139(5), p.054117_1 - 054117_9, 2013/08
Times Cited Count：13 Percentile：45.06(Chemistry, Physical)We propose a novel path sampling method based on the Onsager-Machlup action by generalizing the multiscale enhanced sampling technique. In this method, the system of interest is coupled to a coarse-grained system, which can move more quickly and computed more efficiently than the original system. We simulate this combined system using Lange in dynamics where different heat baths are coupled to the two systems. We apply this method to a model polymer with Asakura-Osawa interaction, and compare the results with the conventional transition path sampling method.
Tc production from (n, 
) MoTanase, Masakazu*; Shiina, Takayuki*; Kimura, Akihiro; Nishikata, Kaori; Fujisaki, Saburo*; Ota, Akio*; Kobayashi, Masaaki*; Yamamoto, Asaki*; Kawauchi, Yukimasa*; Tsuchiya, Kunihiko; et al.
Proceedings of 5th International Symposium on Material Testing Reactors (ISMTR-5) (Internet), 9 Pages, 2012/10
Tc is used as a radiopharmaceutical and manufactured from the parent nuclide of Mo. Extraction method of Tc from (n, ) Mo have been developed, as a part of the industrial use expansion after JMTR will re-start. In this research, the method proposed would be applicable to a practical production of Tc obtained from (n, ) Mo in large quantities. The method proposed would be applicable to a practical production of Tc obtained from (n, ) Mo in large quantities.
Shiga, Motoyuki; Fujisaki, Hiroshi*
Journal of Chemical Physics, 136(18), p.184103_1 - 184103_11, 2012/05
Times Cited Count：12 Percentile：40.78(Chemistry, Physical)We propose a generalization of intrinsic reaction coordinate (IRC) for quantum many-body system described in terms of the mass-weighted centroids, i.e. the mass-weighted center of nuclear masses of the ring polymers in the imaginary-time path integral theory. This novel kind of reaction coordinate, which may be called the "centroid IRC", corresponds to the minimum free energy path that interconnects between the reactant and the product with a least amount of reversible work done on the center of nuclear masses. We provide a numerical recipe to obtain the centroid IRC based on first principles by combining the ab initio path integral simulation and the string method. The method is applied to the NH
and NH
as well as their deuterated isotopomers to study the importance of nuclear quantum effects in the intra- and inter-molecular proton transfer reactions.
Fujisaki, Hiroshi*; Shiga, Motoyuki; Kidera, Akinori*
Journal of Chemical Physics, 132(13), p.134101_1 - 134101_8, 2010/04
Times Cited Count：22 Percentile：59.56(Chemistry, Physical)For sampling multiple pathways in a rugged energy landscape, we propose a novel action-based path sampling method using the Onsager-Machlup action functional. To avoid "path trapping" around an initially guessed path, the path sampling method is further combined with a powerful sampling technique, the replica exchange method. The principle and algorithm of our method is numerically demonstrated for a model two-dimensional system with a bifurcated potential landscape.
Aoyanagi, Shigeo; Oda, Yoshihiro; Sasamoto, Hiroshi; Shibata, Masahiro; Tanai, Kenji; Taniguchi, Naoki; Nishimura, Mayuka; Fujisaki, Kiyoshi; Kikuchi, Hirohito*; Matsumoto, Kazuhiro*
Hoshasei Haikibutsu Anzen Kenkyu Nenji Keikaku (Heisei-13-Nendo
Heisei-17-Nendo) Kenkyu Seika Hokokushu, p.179 - 203, 2006/03
no abstracts in English
Tokuda, Shinji; Okubo, Hiroshi*; Fujisaki, Masahide*; Karube, Yukihiro*
no journal, ,
An MHD (MagnetoHydroDynamic) stability code MARG2D has recently been developed which identifies the stability against ideal MHD perturbations in a tokamak. The code reduces the stability problem to an eigenvalue problem and solves the problem less than ten seconds when a massively parallel computer (SGI Altix 3700Bx2) is used. Real time stability analysis therefore becomes probable since the characteristic time is 
seconds for changing the pressure profile in ITER. To this end we are now developing by using FPGA (Field Programmable Gate Array) a special purpose computer that solves the eigenvalue problem. We report on the progress of this project, especially on matrix operations by FPGA with the study of performance.
Tanaka, Masaaki; Ohshima, Hiroyuki; Yamano, Hidemasa; Aizawa, Kosuke; Oki, Hiroshi*; Fujisaki, Tatsuya*
no journal, ,
Applicability of U-RANS approach with RSM using commercial CFD code (STAR-CD) to the flow through the short-elbow was examined. Before the discussion of the hydraulic phenomena, appropriate numerical options in the current version of the STAR-CD were checked, comparing with the experimental results of velocity profiles and pressure fluctuation. Using the appropriate numerical options for U-RANS approach, numerical simulation for the 1/3-scaled water experiment simulating the hot-leg piping of the JSFR was conducted.
Sasamoto, Hiroshi; Yui, Mikazu; Naito, Morimasa; Walker, C.; Fujisaki, Kiyoshi*; Takase, Hiroyasu*
no journal, ,
Development of a method to evaluate applicability of cementitious materials based on the implications for long-term safety has been performed considering the use of cementitious grout materials for reduction of water leakage during the stages of drilling of drift and implementation. In this study, an approach to evaluate the effects on alteration behavior of rock, the status of development of necessary model and database and a test case for evaluation are presented.
Shiga, Motoyuki; Fujisaki, Hiroshi*
no journal, ,
We propose a new simulation method for simple evaluation of free energy curves of quantum systems by combining ab initio path integral method with string method. In this method, the center of mass positions of nuclei represented in terms of path integral formulation (centroid) is set as configurational variables, and the free energy surface is defined on this configuration space. Then, the minimum free energy reaction path on this surface is searched by the string method. This is one of the ways to generalise the idea of intrinsic reaction coordinate to quantum systems, and it could be useful for analysing proton and deutron transfer reactions.
Shiga, Motoyuki; Fujisaki, Hiroshi*
no journal, ,
This result is an application study of quantum first-principles calculation method on hydrogen-bonded systems developed during the mid-term plan of CCSE. In this talk, I will suggest a new methodology of calculating free energy curves of quantum systems by combining ab initio path integral method and string method. This is one of the ways to apply the idea of intrinsic reaction coordinate to quantum systems, and it is expected to be useful for the analysis of proton and deutron transfer reactions.
Shiga, Motoyuki; Fujisaki, Hiroshi*
no journal, ,
In this paper, I propose a first-principles computational approach to obtain chemical reactions of quantum many-body systems by the extension of Fukui's intrinsic reaction coordinate. For a chemical process from the reactant to the product, we search for a path that passes a barrier in which quantum mechanical free energy is minimum. This opens a way to a first-principles analysis of proton transfer reactions of complex hydrogen bonded systems that involve large amplitude thermal and quantum fluctuations.
Tanaka, Masaaki; Murakami, Satoshi*; Fujisaki, Tatsuya*; Oki, Hiroshi*; Ohno, Shuji; Kamide, Hideki
no journal, ,
Numerical estimation method to analyze unsteady flow phenomena in the upper plenum and the hot-leg piping system in sodium cooled fast reactor has been developed. As for the high cycle thermal fatigue, outline of development status of a numerical simulation code MUGTHES and numerical estimation method including V&V process are explained. As for the flow-induced vibration phenomena, construction of a numerical model of the hot-leg piping integrated into a symmetric half domain of the upper plenum is explained and numerical results relating to applicable numerical schemes and turbulence model (RSM) are briefly mentioned.
Yoshimura, Kazuo; Doda, Norihiro; Oki, Hiroshi*; Fujisaki, Tatsuya*; Tanaka, Masaaki; Vilim, R. B.*
no journal, ,
The CFD analysis of SHRT-17 test in the experimental fast bread reactor of EBR-II, was carried out to investigate the thermal stratification measured in the core upper plenum with the simulation result in the test. From the numerical simulation, it could be confirmed that the driving force of the natural circulation through the whole plant was influenced by the thermal stratification in the upper part of the core upper plenum and in the sloped part of the Z-shaped pipe.
Ichikawa, Nozomi*; Hamamoto, Takafumi*; Sasamoto, Hiroshi; Ichige, Satoru*; Kawakita, Ryohei; Fujisaki, Kiyoshi*
no journal, ,
For model validation of bentonite behavior under high alkaline condition, a batch type reaction experiment and modeling were performed. In the batch type reaction experiment, simulated solutions for the leachate from cement material (Region I solution of pH13 simulated by mixture of both 0.2M NaOH and KOH solutions, Region II solution of pH12.5 simulated by 0.016M CaOH solution) and bentonite (Kunigel V1 and Kunipia F) were reacted under L/S ratio of 50 mL/g and temperature for either 25 or 50 degrees, and for 2 years as the maximum duration. As the results, for example of the experiment for reactions between Region I solution and Kunipia F at 50 degrees, the peak intensity for montmorillonite slightly decreased with time and the new formed secondary mineral suggested as phillipsite occur. Geochemical modeling for this experimental case was performed. Regarding the amount of montmorillonite dissolution, the modeling considering the reactions of both montmorillonite dissolution and ion exchange approximated the experimental result well, however, the addition of the secondary mineral precipitation reaction was less effective. Sensitivity analyses considering the parameter uncertainties of secondary mineral precipitation reaction stimulated that the inconsistency was not dependent on the parameter uncertainties.
