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based on experimental data and density functional theory calculation resultWatanabe, Masashi; Nakamura, Hiroki; Suzuki, Kiichi; Machida, Masahiko; Kato, Masato
Journal of the American Ceramic Society, 105(3), p.2248 - 2257, 2022/03
Times Cited Count：1 Percentile：6.98(Materials Science, Ceramics)Properties of CeO
were evaluated by DFT simulation to determine band gap, Frenkel defect formation energy and defect migration energy. Band gap and Frenkel defect formation energy were used to analyze defect equilibria. Oxygen partial pressure dependence of defect equilibria was evaluated based on oxygen potential experimental data and DFT calculation, and a Brouwer diagram was derived. The defect formation energies, including Frenkel defect, electron-hole pair and so on, were determined and used to evaluate the properties, including oxygen diffusion coefficients, electrical conduction, heat capacity and thermal conductivity. Mechanisms of various properties were discussed for a deeper understanding based on defect chemistry, and the relationship among properties were systematically described.
Ito, Hiroto*; Shiotsu, Hiroyuki; Tanaka, Yoichi*; Nishihara, Satomichi*; Sugiyama, Tomoyuki; Maruyama, Yu
JAEA-Data/Code 2018-012, 42 Pages, 2018/10
JAEA-Data-Code-2018-012.pdf:4.93MB
Chemical composition of fission products transported in nuclear facilities in severe accidents is controlled by slower chemical reaction rates, therefore, it could be different from that evaluated on the chemical equilibrium assumption. Hence, it is necessary to evaluate the chemical composition with reaction kinetics. On the other hand, databases applicable to the analysis of nuclear facilities have not been constructed because knowledge of reaction rates of complex chemical reactions in severe accidents is currently limited. Accordingly, we have developed the CHEMKEq code based on a partial mixed model with chemical equilibrium and reaction kinetics to decrease uncertainties of the chemical composition caused by the reaction rate. The CHEMKEq code, under mass conservation law, firstly evaluates chemical species obeying the chemical equilibrium model, and then, relatively slow reactions are solved by the reaction kinetics model. Moreover, the CHEMKEq code has a multiplicity of use in evaluations of chemical composition because general chemical equilibrium and reaction kinetics models are also available and databases required to calculation are external file formats. This report is the user's guide of the CHEMKEq code, showing models, solution methods, structure of the code and calculation examples. And information to run the CHEMKEq code is summarized in appendixes.
Matsuoka, Seikichi; Idomura, Yasuhiro; Satake, Shinsuke*
Physics of Plasmas, 25(2), p.022510_1 - 022510_10, 2018/02
Times Cited Count：17 Percentile：74.87(Physics, Fluids & Plasmas)Global full-f gyrokinetic simulations, in which the gyrokinetic equation is solved based on the first principle without the scale separation with respect to the plasma distribution function, is attracting much attention in the plasma transport simulation studies. In this work, in order to apply a global full-f gyrokinetic simulation code GT5D to stellarator plasmas with complicated three-dimensional magnetic field configurations, we extend finite difference scheme of GT5D and develop a new interface code which incorporates the three-dimensional magnetic equilibria provided by a standard equilibrium code, VMEC. A series of benchmark calculations are carried out for the numerical verification of GT5D. It is successfully demonstrated that GT5D well reproduces results of a theoretical analysis and another global neoclassical transport code.
by Knudsen effusion mass spectrometryNakajima, Kunihisa; Takai, Toshihide; Furukawa, Tomohiro; Osaka, Masahiko
Journal of Nuclear Materials, 491, p.183 - 189, 2017/08
Times Cited Count：8 Percentile：61.27(Materials Science, Multidisciplinary)One of the main chemical forms of cesium in the gas phase during severe accidents of light water reactor is expected to be cesium metaborate, CsBO, by thermodynamic equilibrium calculation considering reaction with boron. But accuracy of the thermodynamic data of gaseous metaborate, CsBO(g), has been judged as poor quality. Thus, Knudsen effusion mass spectrometric measurement of CsBO was carried out to obtain reliable thermodynamic data. The evaluated values of standard enthalpy of formation of CsBO(g), 
H
(CsBO,g), by the 2nd and 3rd law treatments are -700.7
10.7 kJ/mol and -697.010.6 kJ/mol, respectively, and agree with each other within the errors, which suggests our data are reliable. Further, it was found that the existing data of the Gibbs energy function and the standard enthalpy of formation agreed well with the values evaluated in this study, which indicates the existing thermodynamic data are also reliable.
, I, I
, and CsI on C
fullereneKobayashi, Takanori; Yokoyama, Keiichi
Journal of Nuclear Science and Technology, 53(10), p.1489 - 1493, 2016/10
Times Cited Count：6 Percentile：49.29(Nuclear Science & Technology)Theoretical investigation for the adsorption of the cesium atom (Cs), the cesium iodide molecule (CsI), the iodine atom (I), the cesium cation (Cs), and the iodide anion (I) onto the surface of a single fullerene molecule (C) are reported. A hybrid exchange-correlation functional using the Coulomb-attenuating method (CAM-B3LYP) is employed. The adsorption energies, i.e., the opposite of enthalpy change through adsorption, are calculated to be 34, 3, 2, 11, and 12 kcal mol
for Cs, CsI, I, Cs, and I, respectively. The equilibrium constant for Cs is calculated to be 7
10
atm at the temperature of 1000 K and is seven orders of magnitude higher than that for CsI, indicating that the C molecule adsorb the Cs atom highly selectively against the CsI molecule.
C based on two binary non-ideal solid solutionsWalker, C.; Suto, Shunkichi; Oda, Chie; Mihara, Morihiro; Honda, Akira
Cement and Concrete Research, 79, p.1 - 30, 2016/01
Times Cited Count：69 Percentile：90.65(Construction & Building Technology)Modeling the solubility behavior of calcium silicate hydrate (C-S-H) gel is important to make quantitative predictions of the degradation of hydrated ordinary Portland cement (OPC) based materials. Experimental C-S-H gel solubility data have been compiled from the literature, critically evaluated and supplemented with new data from the current study for molar Ca/Si ratios = 0.2-0.83. All these data have been used to derive a discrete solid phase (DSP) type C-S-H gel solubility model based on two binary non-ideal solid solutions in aqueous solution(SSAS). Features of the DSP type C-S-H gel solubility model include satisfactory predictions of pH values and Ca and Si concentrations for all molar Ca/Si ratios = 2.7 
0 in the C-S-H system, portlandite (CH) for Ca/Si ratios 
1.65, congruent dissolution at Ca/Si ratios = 0.85, and amorphous silica (SiO
) for Ca/Si ratios 
0.55 as identified in the current study by IR spectroscopy.
Kurihara, Kenichi; Itagaki, Masafumi*; Miyata, Yoshiaki; Nakamura, Kazuo*; Urano, Hajime
Purazuma, Kaku Yugo Gakkai-Shi, 91(1), p.10 - 47, 2015/01
no abstracts in English
Maeda, Toshikatsu; Bamba, Tsunetaka*; Mizuno, Tsuyoshi*; Terakado, Shogo; Kitagawa, Isamu; Numata, Masami
Haikibutsu Gakkai Rombunshi, 17(4), p.271 - 281, 2006/07
no abstracts in English
Sherrill, M. E.*; Abdallah, J. Jr.*; Csanak, G.*; Dodd, E. S.*; Fukuda, Yuji; Akahane, Yutaka; Aoyama, Makoto; Inoue, Norihiro*; Ueda, Hideki*; Yamakawa, Koichi; et al.
Physical Review E, 73(6), p.066404_1 - 066404_6, 2006/06
Times Cited Count：29 Percentile：75.69(Physics, Fluids & Plasmas)A model that solves simultaneously both the electron and atomic kinetics was used to generate synthetic He
X-ray spectra to characterize a high intensity ultrashort laser driven Ar cluster target experiment. In particular, level populations were obtained from a detailed collisional-radiative model where collisional rates were computed from a time varying electron distribution function obtained from the solution of the zero dimensional Boltzmann equation. In addition, aparticle-in-cell simulation was used to model the laser interaction with the cluster target and provided the initial electron energy distribution function (EEDF) for the Boltzmann solver. This study suggests that the high density plasma contribution to the time-integrated He spectrum was in a highly non-equilibrium state in both the EEDF and the ion level populations and provides a prediction of 5.7 ps for the average cluster integrity time for this high density state.
Mukai, Masayuki; Tanaka, Tadao; Yukawa, Kazuhiko; Suryantoro*
Genshiryoku Bakkuendo Kenkyu, 12(1-2), p.41 - 51, 2006/03
To evaluate radionuclides migration through geologic media coexistent with colloids in groundwater, a model has been coded. To evaluate an applicability of four models to colloid transport through porous media, breakthrough curves (BTCs) from column experiments using sand and reddish soil have been analyzed. Instantaneous equilibrium model could not explain both timings of breakthrough and reach to C
/C
=1 concurrenyly, however 1st order kinetic reaction model successfully simulate them well. BTCs from the reddish soil column have a particular feature that shows step-wise rising pattern in response to alternately inflow of colloid. Both the instantaneous equilibrium, the 1st order kinetic reaction and filtration models could not simulate this feature, however a 1st order kinetic reaction with filtration capacity model reasonably simulates the feature. The model for colloid transport, given an important role as a part of colloidal migration model of radionuclide, has been validated on the basis of the laboratory experiments.
Sato, Masayasu; Sakurai, Shinji; Nishio, Satoshi; Tobita, Kenji; Inoue, Takashi; Nakamura, Yukiharu; Shinya, Kichiro*; Fujieda, Hirobumi*; DEMO Plant Design Team
Fusion Engineering and Design, 81(8-14), p.1277 - 1284, 2006/02
Times Cited Count：14 Percentile：68.12(Nuclear Science & Technology)no abstracts in English
Asahi, Yoshiro; Suzudo, Tomoaki; Ishikawa, Nobuyuki; Nakatsuka, Toru
Nuclear Science and Engineering, 152(2), p.219 - 235, 2006/02
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)An analysis of a BWR turbine trip experiment was performed with the THYDE-NEU code. The plant was treated as a closed coolant system whose pressure ranges to the atmospheric pressure. To simulate an entire plant, it was found necessary to have the moisture separator model and to account for reversible pressure drops at a junction with an area change. A spatial kinetics model without a notion of reactivity was applied. It was confirmed that THYDE-NEU can perform a coupled neutronic and thermal-hydraulic null transient at the hot full power. Among factors influencing spatial kinetics in the turbine trip were the temporal behavior of the bypass valve opening, the thermal non-equilibrium model and the manner in which to express the coolant density used in the table look-up of cross sections. By adjusting these factors, it was found possible to generate the scram signal when the core averaged LPRM output reached the prescribed value. The other calculated results also were found satisfactorily in agreement with the experimental results.
Kurihara, Kenichi; Kawamata, Yoichi; Sueoka, Michiharu; Hosoyama, Hiroki*; Yonekawa, Izuru; Suzuki, Takahiro; Oikawa, Toshihiro; Ide, Shunsuke; JT-60 Team
Fusion Engineering and Design, 74(1-4), p.527 - 536, 2005/11
Times Cited Count：11 Percentile：59.93(Nuclear Science & Technology)Since tokamak magnetic fusion research has just made a step forward to an international collaborative project ITER, the existing tokamaks including JT-60 are expected to explore more advanced operation scenarios. To test those scenarios in the JT-60 experiment, the basic methods for understanding of plasma equilibrium have been developed. Some of them have been accomplished, and the other are being conducted as follows: (1) A complete plasma shape is precisely reproduced in real time. (2) Eddy current effects are considered for shape reproduction. (3) A plasma current profile in the poloidal cross-section is reproduced in real. (4) For long-pulse DT operation, a method is developed to correct the drifted signal of the integrator for a pick-up coil by employing distant sensor signals. In the symposium, those methods will be explained in detail with the experimental results at JT-60. On the basis of such discussion, we would like to envisage a future of plasma equilibrium control toward ITER and a fusion power plant.
Machida, Masahiko; Koyama, Tomio*; Kato, Masaru*; Ishida, Takekazu*
Physica C, 426-431(1), p.169 - 173, 2005/10
no abstracts in English
Kubo, Shinji; Yoshida, Mitsunori; Sakurai, Makoto*; Tanaka, Kotaro*; Miyashita, Reiko*
Bunri Gijutsu, 35(3), p.148 - 152, 2005/05
no abstracts in English
Watanabe, Masayuki; Mirvaliev, R.*; Tachimori, Shoichi; Takeshita, Kenji*; Nakano, Yoshio*; Morikawa, Koshi*; Chikazawa, Takahiro*; Mori, Ryohei*
Solvent Extraction and Ion Exchange, 22(3), p.377 - 390, 2004/06
Times Cited Count：32 Percentile：65.75(Chemistry, Multidisciplinary)The synergistic extraction with N,N,N',N'-tetrakis(2-methylpyridyl)-ethylenediamine (TPEN) and di(2-ethylhexyl)phosphoric acid (D2EHPA) demonstrates a good selectivity for Am(III) over macro amount of Ln(III) in 1-octanol. The maximum apparent separation factor, which is defined as the ratio of the distribution ratio of Am(III) to that of Eu(III), is ca. 80 while the molar fraction between D2EHPA and TPEN is 2.0. This ratio is corresponding to the result of the spectrophotometric titration, which indicates that TPEN and D2EHPA form an aggregate in 1-octanol and two D2EHPA molecules coordinate to Eu(III) TPEN complex, [Eu(TPEN)]
. In the present study, the association of D2EHPA and TPEN is one of the most important factors for the synergistic extraction and the complexation of TPEN and D2EHPA with Eu(III).
Sakakibara, Satoru*; Kurihara, Kenichi
Purazuma, Kaku Yugo Gakkai-Shi, 80(5), p.364 - 371, 2004/05
This article presents recent progress in magnetic measurements at magnetic confinement systems. The drift-problem of the integrator used in magnetic measurements is one of the major problems for plasma control and estimation of equilibrium parameters in long-pulse operation. In addition, the durability of the sensors such as a magnetic probe, a flux loop, etc., under fusion neutron irradiation environments is also important. The present status of the developments of a long-pulse integrator and a magnetic sensor are reported.
Suzuki, Takahiro; Oikawa, Toshihiro; Isayama, Akihiko; Fujita, Takaaki
Purazuma, Kaku Yugo Gakkai-Shi, 80(5), p.362 - 363, 2004/05
An analytical method to evaluate spatio-temporal change in current density profile directly from the motional Stark effect (MSE) diagnostic is applied to a discharge, where a neo-classical tearing mode (NTM) appeared and was stabilized by electron cyclotron current drive (ECCD). The analysis clearly shows spatially localized decrease in current density at the magnetic island location, implying decrease in bootstrap current due to flattening of pressure profile within the island. When the NTM is stabilized after the start of the ECCD application, increase in current density at the island location is observed.
Watanabe, Masayuki; Nankawa, Takuya*; Yamada, Teppei*; Kimura, Takaumi; Namiki, Kosuke*; Murata, Masaki*; Nishihara, Hiroshi*; Tachimori, Shoichi
Inorganic Chemistry, 42(22), p.6977 - 6979, 2003/11
Times Cited Count：34 Percentile：75.29(Chemistry, Inorganic & Nuclear)A tripodal ligand, tris(2-pyridyl)carbinol affords a novel tetradentate coordination mode in homodinuclear lanthanide complexes, which exhibit remarkably short distance between the metal ions. Strong fluorescence of Eu(III) and Tb(III) complexes with the ligand demonstrate that the ligand has a suitable excited state for energy transfer from the ligand to Eu(III) and Tb(III) center.
Suzuki, Hideya*; Naganawa, Hirochika; Tachimori, Shoichi
Solvent Extraction and Ion Exchange, 21(4), p.527 - 546, 2003/03
Times Cited Count：12 Percentile：45.03(Chemistry, Multidisciplinary)no abstracts in English
