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Funato, Takumi*; Kato, Takeo*; Matsuo, Mamoru
Physical Review B, 106(14), p.144418_1 - 144418_10, 2022/10
Times Cited Count:3 Percentile:45.85(Materials Science, Multidisciplinary)Kaneko, Masashi; Sasaki, Yuji; Wada, Eriko*; Nakase, Masahiko*; Takeshita, Kenji*
Chemistry Letters, 50(10), p.1765 - 1769, 2021/10
Times Cited Count:0 Percentile:0(Chemistry, Multidisciplinary)Density functional theory calculation is applied to predict the stability constants for Eu and Am complexes in aqueous solution for molecular modelling of novel separation agents for minor actinides over lanthanides. Logarithm of experimental stability constants correlates with calculated complex formation enthalpies with high reproducibility (R 0.98). Prediction of stability constants of novel chelates is demonstrated and indicates a potential availability of the derivatives of diethylenetriaminepentaacetic acid type chelate in acidic condition and enhancement of Am selectivity over Eu.
Endo, Tomohiro*; Noguchi, Akihiro*; Yamamoto, Akio*; Tada, Kenichi
Transactions of the American Nuclear Society, 124(1), p.184 - 187, 2021/06
This study confirmed that the sensitivity analysis of the alpha-eigenvalue can be carried even for non-neutron multiplication systems such as water-only systems. The preliminary results of nuclear data-induced uncertainties of alpha-eigenvalue were smaller than the differences between numerical and experimental results of alpha-eigenvalue. For further investigation, it is necessary to reconsider the experimental bias and the nuclear data-induced uncertainty in alpha-eigenvalue due to the thermal scattering law data of water.
Kikuchi, Shin; Sakamoto, Kan*; Takai, Toshihide; Yamano, Hidemasa
Nihon Kikai Gakkai 2020-Nendo Nenji Taikai Koen Rombunshu (Internet), 4 Pages, 2020/09
In a postulated severe accidental condition of sodium-cooled fast reactor (SFR), eutectic melting between boron carbide (BC) as control rod element and stainless steel (SS) as control rod cladding or related structure may occur. Thus, behavior of BC-SS eutectic melting is one of the phenomena to evaluate the core disruptive accidents in SFR. In order to clarify the kinetic feature of BC-SS eutectic melting process in the interface, the thinning test for SS crucibles using the pellets of BC or SS with low BC concentration were performed to obtain the rate constant with dependence of BC concentration against SS. It was found that the rate constants of eutectic melting between SS and SS low BC concentration were smaller than that of BC-SS in the high temperature range. Besides, the rate constant of eutectic melting between SS and BC containing SS became small when decreasing the BC concentration against SS.
Yokoyama, Kenji; Sugino, Kazuteru; Ishikawa, Makoto; Maruyama, Shuhei; Nagaya, Yasunobu; Numata, Kazuyuki*; Jin, Tomoyuki*
JAEA-Research 2018-011, 556 Pages, 2019/03
We have developed a new unified cross-section set ADJ2017, which is an improved version of the unified cross-section set ADJ2010 for fast reactors. The unified cross-section set is used for reflecting information of C/E values (analysis / experiment values) obtained by integral experiment analyses; the values are stored in the standard database for FBR core design via the cross-section adjustment methodology, which integrates with the information such as uncertainty (covariance) of nuclear data, uncertainty of integral experiment / analysis, sensitivity of integral experiment with respect to nuclear data. The ADJ2017 is based on Japan's latest nuclear data library JENDL-4.0 as in the previous version of ADJ2010, and it incorporates more information on integral experimental data sets related to minor actinides (MAs) and degraded plutonium (Pu). In the creation of ADJ2010, a total of 643 integral experimental data sets were analyzed and evaluated, and 488 of the integral experimental data sets were finally selected to be used for the cross-section adjustment. In contrast, we have evaluated a total of 719 data sets, and eventually adopted 620 integral experimental data sets to create ADJ2017. ADJ2017 shows almost the same performance as ADJ2010 for the main neutronic characteristics of conventional sodium-cooled MOX-fuel fast reactors. In addition, for the neutronic characteristics related to MA and degraded Pu, ADJ2017 improves the C/E values of the integral experimental data sets, and reduces the uncertainty induced by the nuclear data. ADJ2017 is expected to be widely used in the analysis and design research of fast reactors. Moreover, it is expected that the integral experimental data sets used for ADJ2017 can be utilized as a standard database of FBR core design.
Yokoyama, Kenji; Kitada, Takanori*
Journal of Nuclear Science and Technology, 56(1), p.87 - 104, 2019/01
Times Cited Count:4 Percentile:40.43(Nuclear Science & Technology)no abstracts in English
Yokoyama, Kenji
Robutsuri No Kenkyu (Internet), (70), 12 Pages, 2018/04
no abstracts in English
Ebihara, Kenichi; Saito, Kei*; Takai, Kenichi*
Proceedings of 2016 International Hydrogen Conference (IHC 2016); Materials Performance in Hydrogen Environments, p.470 - 477, 2017/00
For understanding hydrogen (H) embrittlement of steels, it is necessary to infer the state that defects trap H in the steels. Thermal desorption spectra of H obtained by the thermal desorption spectrometry (TDS) are used for inferring such a state. Because the thermal desorption spectra include the influence of experimental conditions and hydrogen diffusion as well as information of the defects trapping H, it is necessary to interpret the spectra using the numerical simulation. In the presentation, we determined the detrapping and the trapping rate constants which are necessary for the simulation from the experimental spectra obtained for plate specimens which is so small that H diffusion is ignorable. Then we confirmed that the model using the obtained rate constants can simulate the spectra of larger cylindrical specimens, so that it was found that the rate constant for small specimens can be used for the simulation of the spectra for specimens of different shape or size.
Kobayashi, Takanori; Yokoyama, Keiichi
Journal of Nuclear Science and Technology, 53(10), p.1489 - 1493, 2016/10
Times Cited Count:6 Percentile:49.05(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 710 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.
Yokoyama, Kenji; Yamamoto, Akio*
Journal of Nuclear Science and Technology, 53(10), p.1622 - 1638, 2016/10
Times Cited Count:10 Percentile:67.99(Nuclear Science & Technology)On the basis of the minimum variance approach, the unified formulation for three types of the cross-section adjustment methods has been derived in a straightforward way without assuming the normal distribution. These methods are intended to minimize the variances of the predicted target core parameters, the adjusted cross-section set, and the calculated integral experimental values. The first and the second methods are found to be slightly different from the extended and the conventional cross-section adjustment methods based on the Bayesian approach with the normal distribution assumption, respectively. However, they become equivalent in some cases and results. The third method is a new method, which is necessary from the viewpoint of the symmetry of the formulation. The derivation procedure proposed in the present paper is potentially applicable to developing more sophisticated cross-section adjustment methods because of the less assumptions on the probability density function.
Iwamoto, Hiroki; Nishihara, Kenji; Katano, Ryota*; Fukushima, Masahiro; Tsujimoto, Kazufumi
JAEA-Research 2014-033, 82 Pages, 2015/03
The effect of experiments using Transmutation Physics Experimental Facility (TEF-P) is analysed from the viewpoint of the reduction of uncertainties in reactor physics parameters (criticality and coolant void reactivity) of an accelerator-driven system (ADS). The analysis is conducted by the nuclear-data adjustment method using JENDL-4.0 on the assumption that ve types of reactor physics experiments (a total of 44 experiments) are performed in TEF-P: (1) criticality experiment, (2) lead void reactivity experiment, (3) reaction rate ratio experiment, (4) sample reactivity experiment, and (5) fuel replacement reactivity experiment. As the result, 1.0% of uncertainty in criticality is found to be reduced to approximately 0.4%, and effective experiments for the reduction of uncertainty in criticality and coolant void reactivity are shown to be fuel replacement reactivity experiments and lead void reactivity experiments, respectively. Although these effects depend largely on the composition and amount of minor-actinide (MA) fuels, it is found that a combination of different types of experiments and database of existing experiments is effective in reducing the uncertainties.
Nagaishi, Ryuji; Inoue, Masao; Hino, Ryutaro; Ogawa, Toru
Proceedings of 2014 Nuclear Plant Chemistry Conference (NPC 2014) (USB Flash Drive), 9 Pages, 2014/10
Since seawater has been used as a coolant for reactors and spent fuel pools in broken reactor buildings at Fukushima Daiichi NPS accident, radioactive contaminated water emitted following the accident has contained salt content of seawater at high concentrations, different from that at TMI-2 accident. Radiolysis of seawater leading to hydrogen generation and corrosion has been simulated and reported by several groups. However, the proposed radiolysis models cannot be always applied to water radiolysis at the wide range of salt concentrations present in the NPS, mainly because primary yields of radiolysis products of water and radiation-induced reactions are dependent on the salt concentration. In this study, the radiolytic behavior in diluted and concentrated systems of seawater was considered on the basis of results in steady state and pulse radiolysis experiments, in which the above salt effects were demonstrated from the obtained results.
Hoshino, Tsuyoshi; Kobayashi, Takeshi*; Nashimoto, Makoto*; Kawamura, Hiroshi; Dokiya, Masayuki*; Terai, Takayuki*; Yamawaki, Michio*; Takahashi, Yoichi*
JAERI-Conf 2004-012, p.140 - 147, 2004/07
no abstracts in English
Fujii, Yasunori*; Iwamoto, Akira
Physical Review Letters, 91(26), p.261101_1 - 261101_4, 2003/12
Times Cited Count:41 Percentile:82.46(Physics, Multidisciplinary)no abstracts in English
Ishii, Yasutomo; Azumi, Masafumi; Kishimoto, Yasuaki; Leboeuf, J. N.*
Nuclear Fusion, 43(7), p.539 - 546, 2003/07
Times Cited Count:27 Percentile:61.29(Physics, Fluids & Plasmas)no abstracts in English
Yamashita, Toshiyuki; Kuramoto, Kenichi; Nakada, Masami; Yamazaki, Satoshi*; Sato, Tsuyoshi*; Matsui, Tsuneo*
Journal of Nuclear Science and Technology, 39(Suppl.3), p.585 - 591, 2002/11
no abstracts in English
Takano, Masahide; Ito, Akinori; Akabori, Mitsuo; Ogawa, Toru; Numata, Masami; Kizaki, Minoru
Journal of Nuclear Science and Technology, 39(Suppl.3), p.842 - 845, 2002/11
no abstracts in English
Tanai, Kenji; Horita, M.*; Dewa, Katsuyuki*; Goke, Mitsuo*
JNC TN8410 2001-026, 116 Pages, 2002/03
Earthquake resistance for the underground structure is higher than the ground structure. Therefore, the case of examining the earthquake resistance of underground structure was little. However, it carries out the research on the aseismic designing method of underground structure, since the tunnel was struck by Hyogo-ken Nanbu Earthquake, and it has obtained a much knowledge. However, an object of the most study was behavior at earthquake of the comparatively shallow underground structure in the alluvial plain board, and it not carry out the examination on behavior at earthquake of underground structure in the deep rock mass. In the meantime, underground disposal facility of the high level radioactive waste constructs in the deep underground, and it carries out the operation in these tunnels. In addition, it has made almost the general process of including from the construction start to the backfilling to be about 60 years (Japan Nuclear Fuel Cycle Development Institute, 1999). During these periods, it is necessary to also consider the earthquake resistance as underground structure from the viewpoint of the safety of facilities. Then, it extracted future problem as one of the improvement of the basis information for the decision of the safety standard and guideline of the country on earthquake-resistant design of the underground disposal facility, while it carried out investigation and arrangement of earthquake-resistant design cases, guidelines and analysis method on existing underground structure, etc.. And, the research item for the earthquake resistance assessment of underground structure as case study of the underground research laboratory.
Iwamoto, Akira
Suri Kagaku, (465), p.10 - 17, 2002/03
no abstracts in English
Okada, Kenichi*; Tsuneoka, Masaki; Murano, Yoshihiro*; Okawa, Yoshinao
Denki Setsubi Gakkai-Shi, 22(2), p.151 - 158, 2002/02
no abstracts in English