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Journal Articles

Development of ARKADIA-Safety for severe accident evaluation of sodium-cooled fast reactors

Aoyagi, Mitsuhiro; Sonehara, Masateru; Ishida, Shinya; Uchibori, Akihiro; Kawada, Kenichi; Okano, Yasushi; Takata, Takashi

Proceedings of Technical Meeting on State-of-the-art Thermal Hydraulics of Fast Reactors (Internet), 3 Pages, 2022/09

Journal Articles

Oxidation of anatase TiO$$_{2}$$(001) surface using supersonic seeded oxygen molecular beam

Katsube, Daiki*; Ono, Shinya*; Takayanagi, Shuhei*; Ojima, Shoki*; Maeda, Motoyasu*; Origuchi, Naoki*; Ogawa, Arata*; Ikeda, Natsuki*; Aoyagi, Yoshihide*; Kabutoya, Yuito*; et al.

Langmuir, 37(42), p.12313 - 12317, 2021/10

 Times Cited Count:1 Percentile:7.58(Chemistry, Multidisciplinary)

We investigated the oxidation of oxygen vacancies at the surface of anatase TiO$$_{2}$$(001) using supersonic seeded molecular beam (SSMB) of oxygen. The oxygen vacancies at the top-surface and sub-surface could be eliminated by the supply of oxygen using an SSMB. These results indicate that the interstitial vacancies can be mostly assigned to oxygen vacancies, which can be effectively eliminated by using an oxygen SSMB. Oxygen vacancies are present on the surface of anatase TiO$$_{2}$$(001) when it is untreated before transfer to a vacuum chamber. These vacancies, which are stable in the as-grown condition, could also be effectively eliminated using the oxygen SSMB.

Journal Articles

Compressing the time series of five dimensional distribution function data from gyrokinetic simulation using principal component analysis

Asahi, Yuichi; Fujii, Keisuke*; Heim, D. M.*; Maeyama, Shinya*; Garbet, X.*; Grandgirard, V.*; Sarazin, Y.*; Dif-Pradalier, G.*; Idomura, Yasuhiro; Yagi, Masatoshi*

Physics of Plasmas, 28(1), p.012304_1 - 012304_21, 2021/01

AA2020-0790.pdf:7.13MB

 Times Cited Count:4 Percentile:46.45(Physics, Fluids & Plasmas)

This article demonstrates a data compression technique for the time series of five dimensional distribution function data based on Principal Component Analysis (PCA). Phase space bases and corresponding coefficients are constructed by PCA in order to reduce the data size and the dimensionality. It is shown that about 83% of the variance of the original five dimensional distribution can be expressed with 64 components. This leads to the compression of the degrees of freedom from $$1.3times 10^{12}$$ to $$1.4times 10^{9}$$. One of the important findings - resulting from the detailed analysis of the contribution of each principal component to the energy flux - deals with avalanche events, which are found to be mostly driven by coherent structures in the phase space, indicating the key role of resonant particles.

Journal Articles

Optical properties of trinuclear citrate complexes containing 4f and 5f block metals

Aoyagi, Noboru; Palladino, G.*; Nagasaki, Shinya*; Kimura, Takaumi

Bulletin of the Chemical Society of Japan, 91(6), p.882 - 890, 2018/06

 Times Cited Count:1 Percentile:4.29(Chemistry, Multidisciplinary)

The speciation and coordination geometries of M(III)-citrate complexes in aqueous solutions, where M denotes Eu, Tb, Lu, or Cm, are studied using potentiometric titration, nuclear magnetic resonance spectroscopies. Their photophysical properties are also characterized by time-resolved fluorescence spectra. The formation constants of mononuclear, dinuclear, and trinuclear Lu-citrate species were determined by potentiometric titration in 3.00 M NaClO$$_{4}$$ aqueous media. Terminal carboxylic conformation in trinuclear complexes comprised both the five- and six-membered rings at different exchanging rates. Hydration states evaluated for Eu$$^{3+}$$ ions are the chemical formula of [Eu(Cit)$$_{2}$$ (H$$_{2}$$ O)$$_{2.5}$$ ]$$^{3-}$$ and [Eu$$_{3}$$(OH)$$_{4}$$(Cit)$$_{4}$$(H$$_{2}$$O)$$_{3.4}$$]$$^{7-}$$. These complexes in aqueous solution have geometrical similarity to the crystal structures in the literature. Furthermore, the entity of the hetero-trinuclear complex induces the intramolecular energy transfer from Tb$$^{3+}$$ to Eu$$^{3+}$$. The incorporation of Cm$$^{3+}$$ into these homo/hetero-trinuclear citrate complexes proved to be a successful trial to probe the formation of actinide polymer at a trace level.

Journal Articles

Progress report of Japanese simulation research projects using the high-performance computer system Helios in the International Fusion Energy Research Centre

Ishizawa, Akihiro*; Idomura, Yasuhiro; Imadera, Kenji*; Kasuya, Naohiro*; Kanno, Ryutaro*; Satake, Shinsuke*; Tatsuno, Tomoya*; Nakata, Motoki*; Nunami, Masanori*; Maeyama, Shinya*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 92(3), p.157 - 210, 2016/03

The high-performance computer system Helios which is located at The Computational Simulation Centre (CSC) in The International Fusion Energy Research Centre (IFERC) started its operation in January 2012 under the Broader Approach (BA) agreement between Japan and the EU. The Helios system has been used for magnetised fusion related simulation studies in the EU and Japan and has kept high average usage rate. As a result, the Helios system has contributed to many research products in a wide range of research areas from core plasma physics to reactor material and reactor engineering. This project review gives a short catalogue of domestic simulation research projects. First, we outline the IFERC-CSC project. After that, shown are objectives of the research projects, numerical schemes used in simulation codes, obtained results and necessary computations in future.

Journal Articles

Utilization status of the electron accelerator and the $$gamma$$-ray irradiation facilities

Agematsu, Takashi; Uno, Sadanori; Hanaya, Hiroaki; Yamagata, Ryohei; Seito, Hajime; Nagao, Yuto; Yamasaki, Shota; Kawashima, Ikuo*; Yagi, Norihiko*; Takagi, Masahide*; et al.

JAEA-Review 2015-022, JAEA Takasaki Annual Report 2014, P. 173, 2016/02

The electron accelerator and the three $$gamma$$-ray irradiation facilities of Takasaki Advanced Radiation Research Institute were operated for various research subjects according to the operation plan in FY 2014. The number of research subjects in FY 2014 decreased at the electron accelerator with operation stop by accelerator trouble, and increased slightly at the $$gamma$$-ray irradiation facilities as compared with FY 2013, and research subjects were 205 and 857, respectively. Among these research subjects, 35 and 172 related to recovery from the Fukushima Daiichi Nuclear disaster, respectively, were performed at the electron accelerator and the $$gamma$$-ray irradiation facilities, respectively.

Journal Articles

Operation of the electron accelerator and the $$^{60}$$Co $$gamma$$-ray irradiation facilities

Uno, Sadanori; Hanaya, Hiroaki; Yamagata, Ryohei; Seito, Hajime; Nagao, Yuto; Yamasaki, Shota; Agematsu, Takashi; Kawashima, Ikuo*; Yagi, Norihiko*; Takagi, Masahide*; et al.

JAEA-Review 2015-022, JAEA Takasaki Annual Report 2014, P. 172, 2016/02

This paper reports on the operation status of the $$gamma$$-ray irradiation facilities and the electron accelerator in fiscal 2014 at the Takasaki Advanced Radiation Research Institute of JAEA. The $$gamma$$-ray irradiation facilities were operated smoothly, whereas the electron accelerator stopped for five months because of successive troubles of discharge due to deterioration of equipment over thirty-four years. The annual operation times of the $$gamma$$-ray irradiation facilities of the first, second and food buildings were 19,907, 13,831 and 7,293 hours, respectively, and that of the electron accelerator was 746 hours. The $$gamma$$-ray irradiation facilities were replenished with new five sources of 2.22 PBq, and twenty old sources were removed for disposal. The electron accelerator was repaired for each trouble, however, the complete recovery has not yet been achieved.

Journal Articles

Current status of the electron accelerator at TARRI, JAEA

Uno, Sadanori; Hanaya, Hiroaki; Yamasaki, Shota; Yamagata, Ryohei; Seito, Hajime; Nagao, Yuto; Agematsu, Takashi; Kawashima, Ikuo*; Yagi, Norihiko*; Takagi, Masahide*; et al.

Dai-28-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.121 - 123, 2015/12

no abstracts in English

Journal Articles

Cross-scale interactions between electron and ion scale turbulence in a tokamak plasma

Maeyama, Shinya*; Idomura, Yasuhiro; Watanabe, Tomohiko*; Nakata, Motoki*; Yagi, Masatoshi; Miyato, Naoaki; Ishizawa, Akihiro*; Nunami, Masanori*

Physical Review Letters, 114(25), p.255002_1 - 255002_5, 2015/06

 Times Cited Count:84 Percentile:95.13(Physics, Multidisciplinary)

Multiscale gyrokinetic turbulence simulations with the real ion-to-electron mass ratio and $$beta$$ value are realized for the first time, where the $$beta$$ value is given by the ratio of plasma pressure to magnetic pressure and characterizes electromagnetic effects on microinstabilities. Numerical analysis at both the electron scale and the ion scale is used to reveal the mechanism of their cross-scale interactions. Even with the real- mass scale separation, ion-scale turbulence eliminates electron-scale streamers and dominates heat transport, not only of ions but also of electrons. When the ion-scale modes are stabilized by finite-$$beta$$ effects, the contribution of the electron-scale dynamics to the turbulent transport becomes non-negligible and turns out to enhance ion-scale turbulent transport.

Journal Articles

Utilization status of the electron accelerator and the $$gamma$$-ray irradiation facilities

Agematsu, Takashi; Hanaya, Hiroaki; Yamagata, Ryohei; Seito, Hajime; Nagao, Yuto; Kaneko, Hirohisa; Yamaguchi, Toshiyuki*; Kawashima, Ikuo*; Yagi, Norihiko*; Takagi, Masahide*; et al.

JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 183, 2015/03

The electron accelerator and the three $$gamma$$-ray irradiation facilities were operated for various research subjects according to the operation plan in FY 2013. The number of research subjects at the electron accelerator and at the $$gamma$$-ray irradiation facilities kept constant from FY 2012. Among these research subjects, 47 and 91 ones respectively performed at the electron accelerator and the $$gamma$$-ray irradiation facilities were relevant to recovery from the Fukushima Daiichi nuclear disaster.

Journal Articles

Operation of the electron accelerator and the $$gamma$$-ray irradiation facilities

Agematsu, Takashi; Hanaya, Hiroaki; Yamagata, Ryohei; Seito, Hajime; Nagao, Yuto; Kaneko, Hirohisa; Yamaguchi, Toshiyuki*; Kawashima, Ikuo*; Yagi, Norihiko*; Takagi, Masahide*; et al.

JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 182, 2015/03

The electron accelerator and the $$gamma$$-ray irradiation facility have been operated approximately smoothly. The annual operation time in FY 2013 for the electron accelerator, the first, the second cobalt irradiation facility and food irradiation facility are 1242 h, 18,900 h, 11,804 h and 6,587 h, respectively. Typically repairs were next ones. The SF$$_{6}$$ gas withdrawal system was renewed at the electron accelerator. The 600 m$$^{3}$$ water storage tank was installed to keep pool-water for the cobalt facilities maintenance. New pieces of $$^{60}$$Co sources were purchased and loaded to the first and the second irradiation facility. The maintenance check was done for the food irradiation facility.

Journal Articles

Comparison between kinetic-ballooning-mode-driven turbulence and ion-temperature-gradient-driven turbulence

Maeyama, Shinya; Ishizawa, Akihiro*; Watanabe, Tomohiko*; Nakata, Motoki; Miyato, Naoaki; Yagi, Masatoshi; Idomura, Yasuhiro

Physics of Plasmas, 21(5), p.052301_1 - 052301_12, 2014/05

 Times Cited Count:15 Percentile:59.65(Physics, Fluids & Plasmas)

Journal Articles

Utilization status of the electron accelerator and the $$gamma$$-ray irradiation facilities

Agematsu, Takashi; Haruyama, Yasuyuki; Hanaya, Hiroaki; Yamagata, Ryohei; Seito, Hajime; Nagao, Yuto; Kaneko, Hirohisa; Yamaguchi, Toshiyuki*; Yagi, Norihiko*; Takagi, Masahide*; et al.

JAEA-Review 2013-059, JAEA Takasaki Annual Report 2012, P. 181, 2014/03

The electron accelerator and the three $$gamma$$-ray irradiation facilities were operated for various research subjects according to the operation plan in FY 2012. The number of research subjects at the electron accelerator kept constant compared with FY 2011. The number of research subjects at the $$gamma$$-ray irradiation facilities slightly decreased year after year. Of all these research subjects, 14 ones at the electron accelerator and 93 ones at the $$gamma$$-ray irradiation facilities were relevant to the Fukushima Daiichi nuclear disaster.

Journal Articles

Operation of the electron accelerator and the $$gamma$$-ray irradiation facilities

Agematsu, Takashi; Haruyama, Yasuyuki; Hanaya, Hiroaki; Yamagata, Ryohei; Seito, Hajime; Nagao, Yuto; Kaneko, Hirohisa; Yamaguchi, Toshiyuki*; Yagi, Norihiko*; Takagi, Masahide*; et al.

JAEA-Review 2013-059, JAEA Takasaki Annual Report 2012, P. 180, 2014/03

The electron accelerator and the $$gamma$$-ray irradiation facility have been operated without serious trouble. The annual operation time in FY 2012 for the electron accelerator, the first, the second cobalt irradiation facility and food irradiation facility are 910 h, 15,738 h, 10,537 h and 7,871 h, respectively. Typicaly repairs were next ones. The SF6 gas withdrawal system broke of the accelerator, and there was trouble of mixing in of air. The maintenance check of the first irradiation facility was done. The $$^{60}$$Co ources were purchased and loaded to the first irradiation facility. Fifteen pencil sources of $$^{60}$$Co with length of 30 cm each, twelve ball sources of $$^{60}$$Co and five $$^{137}$$Cs source were disposed of, and they were transferred to Japan Radioisotope Association (JRIA).

Journal Articles

Operation of the electron accelerator and the $$gamma$$-ray irradiation facilities

Agematsu, Takashi; Haruyama, Yasuyuki; Hanaya, Hiroaki; Yamagata, Ryohei; Seito, Hajime; Nagao, Yuto; Kaneko, Hirohisa; Yamaguchi, Toshiyuki*; Yagi, Norihiko*; Takagi, Masahide*; et al.

JAEA-Review 2012-046, JAEA Takasaki Annual Report 2011, P. 174, 2013/01

The electron accelerator and the $$gamma$$-ray irradiation facility have been operated without serious trouble. The annual operation time in FY 2011 for the electron accelerator, the first, the second cobalt irradiation facility and food irradiation facility are 1,059 h, 18,722 h, 9,976 h and 7,427 h, respectively. Typically repairs were next ones. The beam control circuit trouble and the isolation trouble by mixing in of air into SF$$_{6}$$ gas at electron accelerator were repaired. The maintenance check of the second irradiation facility was done. The $$^{60}$$Co sources were purchased and loaded to the second irradiation facility. Forty five pencil sources of $$^{60}$$Co with length of 30 cm each, eight coin sources of $$^{60}$$Co and the $$gamma$$-ray radiographic apparatus with a $$^{60}$$Co source were disposed to Japan Radioisotope Association (JRIA).

Journal Articles

Utilization of the electron accelerator and the $$gamma$$-ray irradiation facilities

Haruyama, Yasuyuki; Agematsu, Takashi; Hanaya, Hiroaki; Yamagata, Ryohei; Seito, Hajime; Nagao, Yuto; Kaneko, Hirohisa; Yamaguchi, Toshiyuki*; Yagi, Norihiko*; Takagi, Masahide*; et al.

JAEA-Review 2012-046, JAEA Takasaki Annual Report 2011, P. 175, 2013/01

The electron accelerator and the three $$gamma$$-ray irradiation facilities were operated for various research subjects according to the operation plan in FY 2011 without serious trouble. The number of research subjects at the electron accelerator increased in the research fields of nuclear facilities and resources & biotechnology, and decreased in the fields of material processing and material for space. The number of research subjects at the $$gamma$$-ray irradiation facilities increased in the fields of material for space and material processing, and decreased in the fields of nuclear facilities and resources & biotechnology. Of all these research subjects, 15 ones at the electron accelerator and 94 ones at the $$gamma$$-ray irradiation facilities were relevant to the Fukushima Daiichi nuclear disaster.

Journal Articles

Luminescence and potentiometric studies on the complexation of europium(III) by picolinate in an aqueous solution

Aoyagi, Noboru; Toraishi, Takashi*; Nagasaki, Shinya*; Tanaka, Satoru*

Journal of Applied Solution Chemistry and Modeling, 1(2), p.148 - 155, 2012/12

Journal Articles

Speciation of Eu$$^{3+}$$ bound to humic substances by time-resolved laser fluorescence spectroscopy (TRLFS) and parallel factor analysis (PARAFAC)

Lukman, S.*; Saito, Takumi*; Aoyagi, Noboru; Kimura, Takaumi; Nagasaki, Shinya*

Geochimica et Cosmochimica Acta, 88, p.199 - 215, 2012/07

 Times Cited Count:21 Percentile:54.14(Geochemistry & Geophysics)

Journal Articles

Surface speciation of Eu$$^{3+}$$ adsorbed on kaolinite by time-resolved laser fluorescence spectroscopy (TRLFS) and parallel factor analysis (PARAFAC)

Ishida, Keisuke*; Saito, Takumi*; Aoyagi, Noboru; Kimura, Takaumi; Nagaishi, Ryuji; Nagasaki, Shinya*; Tanaka, Satoru*

Journal of Colloid and Interface Science, 374(1), p.258 - 266, 2012/05

 Times Cited Count:26 Percentile:55.95(Chemistry, Physical)

Journal Articles

Operation of the electron accelerator and $$gamma$$-ray irradiation facilities

Haruyama, Yasuyuki; Hanaya, Hiroaki; Yamagata, Ryohei; Seito, Hajime; Nagao, Yuto; Kaneko, Hirohisa; Yamaguchi, Toshiyuki*; Yagi, Norihiko*; Takagi, Masahide*; Kawashima, Ikuo*; et al.

JAEA-Review 2011-043, JAEA Takasaki Annual Report 2010, P. 174, 2012/01

The electron accelerator and $$gamma$$-ray irradiation facilities have been operated without serious troubles before the earthquake happened in March 11 2011. The electron accelerator and $$gamma$$-ray irradiation facilities were stopped with concern about the earthquake damage, for 13 and 20 days, respectively.

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