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Journal Articles

Design and actual performance of J-PARC 3 GeV rapid cycling synchrotron for high-intensity operation

Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.

Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09

 Times Cited Count:1 Percentile:58.67(Nuclear Science & Technology)

In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.

Journal Articles

An Automotive intelligent catalyst that contributes to hydrogen safety for the Decommissioning of Fukushima Daiichi Nuclear Power Station (1FD)

Tanaka, Hirohisa*; Masaki, Sayaka*; Aotani, Takuro*; Inagawa, Kohei*; Iwata, Sogo*; Aida, Tatsuya*; Yamamoto, Tadasuke*; Kita, Tomoaki*; Ono, Hitomi*; Takenaka, Keisuke*; et al.

SAE Technical Paper 2022-01-0534 (Internet), 10 Pages, 2022/03

Journal Articles

Identification of hydrogen species on Pt/Al$$_{2}$$O$$_{3}$$ by ${it in situ}$ inelastic neutron scattering and their reactivity with ethylene

Yamazoe, Seiji*; Yamamoto, Akira*; Hosokawa, Saburo*; Fukuda, Ryoichi*; Hara, Kenji*; Nakamura, Mitsutaka; Kamazawa, Kazuya*; Tsukuda, Tatsuya*; Yoshida, Hisao*; Tanaka, Tsunehiro*

Catalysis Science & Technology, 11(1), p.116 - 123, 2021/01

 Times Cited Count:4 Percentile:36.19(Chemistry, Physical)

Journal Articles

Probabilistic risk assessment method development for high temperature gas-cooled reactors, 1; Project overviews

Sato, Hiroyuki; Nishida, Akemi; Ohashi, Hirofumi; Muramatsu, Ken*; Muta, Hitoshi*; Itoi, Tatsuya*; Takada, Tsuyoshi*; Hida, Takenori*; Tanabe, Masayuki*; Yamamoto, Tsuyoshi*; et al.

Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 7 Pages, 2017/04

JAEA, in conjunction with Tokyo City University, The University of Tokyo and JGC Corporation, have started development of a PRA method considering the safety and design features of HTGR. The primary objective of the project is to develop a seismic PRA method which enables to provide a reasonably complete identification of accident scenario including a loss of safety function in passive system, structure and components. In addition, we aim to develop a basis for guidance to implement the PRA. This paper provides the overview of the activities including development of a system analysis method for multiple failures, a component failure data using the operation and maintenance experience in the HTTR, seismic fragility evaluation method, and mechanistic source term evaluation method considering failures in core graphite components and reactor building.

Journal Articles

Probabilistic risk assessment method development for high temperature gas-cooled reactors, 2; Development of accident sequence analysis methodology

Matsuda, Kosuke*; Muramatsu, Ken*; Muta, Hitoshi*; Sato, Hiroyuki; Nishida, Akemi; Ohashi, Hirofumi; Itoi, Tatsuya*; Takada, Tsuyoshi*; Hida, Takenori*; Tanabe, Masayuki*; et al.

Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 7 Pages, 2017/04

This paper proposes a set of procedures for accident sequence analysis in seismic PRAs of HTGRs that can consider the unique accident progression characteristics of HTGRs. Main features of our proposed procedure are as follows: (1) Systematic analysis techniques including Master Logic Diagrams are used to ensure reasonable completeness in identification of initiating events and classification of accident sequences, (2) Information on factors that govern the accident progression and source terms are effectively reflected to the construction of event trees for delineation of accident sequences, and (3) Frequency quantification of seismically-initiated accident sequence frequencies that involve multiplepipe ruptures are made with the use of the Direct Quantification of Fault Trees by Monte Carlo (DQFM) method by a computer code SECOM-DQFM.

Journal Articles

Diffusion behavior of D$$_{2}$$O in the film on Fe oxidized at high temperature in air

Haruna, Takumi*; Yamamoto, Tatsuya*; Miyairi, Yoji*; Shibata, Toshio*; Taniguchi, Naoki; Sakamaki, Keiko; Tachikawa, Hirokazu*

Zairyo To Kankyo, 64(5), p.201 - 206, 2015/05

Diffusion coefficients of D$$_{2}$$O in the films was determined in order to estimate corrosion rate of carbon steel for the overpack in ground water. Fe plates were heated to form oxide films. The films were characterized with XRD and SEM. After that, the specimen was contacted with D$$_{2}$$O for 5184 ks, followed by subjected to TDS to obtain an amount of D$$_{2}$$O absorbing into the film. As a result, single-layered film of Fe$$_{3}$$O$$_{4}$$ was formed at 573 and 723 K, and double-layered film of Fe$$_{2}$$O$$_{3}$$ and Fe$$_{3}$$O$$_{4}$$ was formed at 873 K. It was found that an amount of D$$_{2}$$O in the film correlated linearly with a square root of the absorption period, and that the amount was steady for a long period. From the results and Fick's second law, diffusion coefficients of D$$_{2}$$O was determined as 9.7$$times$$10$$^{-13}$$ cm$$^{2.}$$s$$^{-1}$$ for the Fe$$_{3}$$O$$_{4}$$ film, and 5.5$$times$$10$$^{-13}$$ cm$$^{2.}$$s$$^{-1}$$ to 2.2$$times$$10$$^{-12}$$ cm$$^{2.}$$s$$^{-1}$$ for Fe$$_{2}$$O$$_{3}$$ film.

Journal Articles

Analysis on effects of transverse electric field in an injector cavity of compact-ERL at KEK

Hwang, J.-G.*; Kim, E.-S.*; Miyajima, Tsukasa*; Honda, Yosuke*; Harada, Kentaro*; Shimada, Miho*; Takai, Ryota*; Kume, Tatsuya*; Nagahashi, Shinya*; Obina, Takashi*; et al.

Nuclear Instruments and Methods in Physics Research A, 753, p.97 - 104, 2014/07

 Times Cited Count:7 Percentile:50.6(Instruments & Instrumentation)

Journal Articles

HBC foil beam study and long-term observation at the 3-GeV RCS in J-PARC

Yoshimoto, Masahiro; Saha, P. K.; Yamazaki, Yoshio; Kawase, Masato; Saeki, Riuji; Hayashi, Naoki; Yamamoto, Kazami; Hotchi, Hideaki; Ishiyama, Tatsuya; Kinsho, Michikazu; et al.

Journal of Physics; Conference Series, 417, p.012073_1 - 012073_6, 2013/03

 Times Cited Count:4 Percentile:76.89

The HBC foil are installed in the J-PARC RCS for the charge-exchange H$$^{-}$$ beam injection. In order to examine the characteristics of the HBC foils, beam studies for the HBC foil were carried out from the viewpoint of foil's life time and the beam survival rate due to foils. According to the compromise between charge-exchange efficiency and foil scattering beam loss, we optimized the foils thickness for user operation. The long-term observation during the user operation as well as the HBC foil endurance test for its life time evaluation was carried out. Even after one year was operation, there was no deterioration of the stripping foil.

Journal Articles

Analysis of buried heterointerfacial hydrogen in highly lattice-mismatched epitaxy on silicon

Yamazaki, Tatsuya; Asaoka, Hidehito; Taguchi, Tomitsugu; Yamamoto, Shunya; Yamazaki, Dai; Maruyama, Ryuji; Takeda, Masayasu; Shamoto, Shinichi

Thin Solid Films, 520(8), p.3300 - 3303, 2012/02

 Times Cited Count:2 Percentile:10.41(Materials Science, Multidisciplinary)

We succeeded in realizing the epitaxial growth of a Sr layer on Si(111) with an atomically abrupt heterointerface - in spite of its large lattice mismatch (12%) with Si - by introducing a monoatomic layer of H on Si. In order to identify the buried H, we carried out a combination analysis involving neutron reflectometry and resonant nuclear reaction of $$^{1}$$H($$^{15}$$N,$$alpha$$$$gamma$$)$$^{12}$$C analysis. We found different neutron reflectivity profiles resulting from a contrast variation between the H and D atoms at the buried heterointerface. Furthermore, the depth $$gamma$$-ray intensity profiles revealed that the H at the heterointerface acts as an effective buffer layer that enables it to manage the highly mismatched epitaxy on Si.

Journal Articles

Analysis of dissolved hydrogen concentration utilizing of channel-flow-electrode method

Miura, Tatsuya*; Nishikata, Atsushi*; Tsuru, Toru*; Yamamoto, Masahiro; Uchiyama, Gunzo; Nojima, Yasuo*; Fujine, Sachio*

Fushoku Boshoku Kyokai Dai-58-Kai Zairyo To Kankyo Toronkai Koenshu, p.15 - 16, 2011/09

There exist some equipments made of Ti or Ti-5Ta alloy in the spent nuclear fuel reprocessing plant. These equipments are investigated for failure by hydrogen embrittlement. To evaluate the stabilities of hydrogen in the solutions using at the reprocessing plant, channel-flow-ellectrode (CFE) method was utilized. The method to determine the dissolved hydrogen concentration was considered from the results of anodic polarization curves.

Journal Articles

Beam study results with HBC stripping foils at the 3-GeV RCS in J-PARC

Yoshimoto, Masahiro; Yamazaki, Yoshio; Hayashi, Naoki; Yamamoto, Kazami; Saeki, Riuji; Hotchi, Hideaki; Saha, P. K.; Harada, Hiroyuki; Kawase, Masato; Ishiyama, Tatsuya; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.3927 - 3929, 2010/05

The ($underline{H}$)ybrid type thick ($underline{B}$)oron-doped ($underline{C}$)arbon (HBC) stripping foils are installed and used for the beam injection at the 3GeV RCS (Rapid Cycling Synchrotron) in J-PARC (Japan Proton Accelerator Research Complex). Up to now, the performance deterioration of the stripping foils can not be seen after the long beam irradiation for the 120kW user operation and 300kW high power beam demonstration at the RCS. In order to examine the characteristic of the HBC foils, various beam studies were carried out. The beam-irradiated spot at the foil was measured by scanning the foil setting position, the charge exchange efficiency was evaluated with various thickness foils, and the effect of the SiC fibers supporting the foil mounting was checked with different mounting foils. Beam study results obtained with using the HBC foils will be presented. In addition, the trends of outgas from the stripping foils and the deformations of the foils during the beam irradiation will be reported.

Journal Articles

Initial oxidation of Si(110) surface evaluated by photoemission spectroscopy and substrate-curvature measurements

Yamamoto, Yoshihisa*; Suzuki, Yasushi*; Miyamoto, Yu*; Bantaculo, R.*; Suemitsu, Maki*; Enta, Yoshiharu*; Teraoka, Yuden; Yoshigoe, Akitaka; Asaoka, Hidehito; Yamazaki, Tatsuya

Hakumaku, Hyomen Butsuri Bunkakai, Shirikon Tekunoroji Bunkakai Kyosai Tokubetsu Kenkyukai Kenkyu Hokoku, p.207 - 210, 2009/01

The bending of Si substrate has been measured optically in the oxidation of Si(110) surface and variation of curvature for (001) and (-110) directions have been evaluated. Furthermore, time evolutions of oxygen adsorption content and its chemical bonding states have been measured by photoemission spectroscopy to discuss inisotropy of the Si(110) oxidation in comjunction with substrate curvature measurements. Oxygen adsorption content was evaluated from O1s photoemission and chemical bonding states were evaluated from Si2p photoemission. O$$_{2}$$ gas pressure was ranging from 5.0$$times$$10$$^{-6}$$ Pa to 6.7$$times$$10$$^{-6}$$ and substrate temperature was 873 K. Compressive stress was detected in the (-110) direction. In turn, stretching stress was detected. The photoemission spectroscopy indicated that a layer-by-layer oxidation was not took place. The stretching stress in the (001) direction implies that oxidation of B-bonds which have components along the (001) direction takes place.

Journal Articles

Ga NQR relaxation rates in superconductor PuRhGa$$_5$$

Sakai, Hironori; Kambe, Shinsaku; Tokunaga, Yo; Fujimoto, Tatsuya; Walstedt, R. E.*; Yasuoka, Hiroshi; Aoki, Dai*; Homma, Yoshiya*; Yamamoto, Etsuji; Nakamura, Akio; et al.

Journal of Physics and Chemistry of Solids, 68(11), p.2103 - 2106, 2007/11

 Times Cited Count:1 Percentile:7.14(Chemistry, Multidisciplinary)

A lot of attention is currently focused on Pu-based superconductors. These systems have relatively high superconducting (SC) transition temperatures, ${it i.e.,}$ $$T_{rm c}simeq$$ 18 K for PuCoGa$$_{5}$$ and $$T_{rm c}simeq$$ 9 K for PuRhGa$$_{5}$$. Both compounds crystallize in the tetragonal HoCoGa$$_{5}$$ (115) structure, which is well known for the heavy-fermion SC systems Ce$$T$$In$$_{5}$$ ($$T$$=Co, Rh, Ir)with $$T_{rm c} sim$$ 2 K at most. Recently, NMR and NQR experiments have been reported for PuCoGa$$_{5}$$ by Curro et al. and for PuRhGa$$_{5}$$ by our group. In both cases, measurements of $$1/T_{1}$$ using NQR have revealed that the Pu115 superconductors show unconventional superconductivity with an anisotropic gap. Now we have measured the more detailed data of $$1/T_{1}$$ for NQR lines in PuRhGa$$_5$$, especially focusing on the low-lying magnetic excitation in the normal state. From the viewpoint of spin-fluctuations, we will discuss the difference between PuRhGa$$_{5}$$ and PuCoGa$$_{5}$$ and between superconducting Pu115 and non-superconducting An115 series.

Journal Articles

$$^{17}$$O NMR spin-lattice relaxation in NpO$$_2$$; Field-dependent cross-relaxation process driven by $$^{237}$$Np spins

Tokunaga, Yo; Walstedt, R. E.*; Homma, Yoshiya*; Aoki, Dai*; Kambe, Shinsaku; Sakai, Hironori; Fujimoto, Tatsuya; Ikeda, Shugo; Yamamoto, Etsuji; Nakamura, Akio; et al.

Journal of Physics and Chemistry of Solids, 68(11), p.2016 - 2019, 2007/11

 Times Cited Count:2 Percentile:12.76(Chemistry, Multidisciplinary)

In this paper, we report a comprehensive study of $$^{17}$$O nuclear spin-lattice relaxation in NpO$$_2$$ for a wide range of fields and temperatures. In both the paramagnetic and ordered-state regions, a strong, field-dependent $$^{237}$$Np -$$^{17}$$O nuclei cross-relaxation process is observed in addition to the expected background rate. The cross relaxation process, driven by the $$^{237}$$Np spins, is conveyed to the $$^{17}$$O via a greatly enhanced indirect nuclear spin-spin coupling which is described and reported here for the first time. The magnitude and temperature dependence of the indirect coupling are in reasonable accord with a simple theoretical model. The magnitude and temperature dependence of the $$^{237}$$Np $$T_1$$ process are also deduced from the data obtained.

Journal Articles

NMR studies of actinide dioxides

Tokunaga, Yo; Sakai, Hironori; Fujimoto, Tatsuya; Kambe, Shinsaku; Walstedt, R. E.*; Ikushima, Kenji*; Yasuoka, Hiroshi; Aoki, Dai*; Homma, Yoshiya*; Haga, Yoshinori; et al.

Journal of Alloys and Compounds, 444-445, p.241 - 245, 2007/10

 Times Cited Count:18 Percentile:68.03(Chemistry, Physical)

In this paper, we present our recent NMR works on Neptunium and Plutonium compounds. In order to elucidate the nature of the exotic multipolar ordered phase of NpO$$_2$$, we have initiated the first NMR measurements on this system. We have shown that direct observation of multipole order parameters is possible by means of NMR. Our NMR results provide further insight into the microscopic nature of multipole phase transitions in f-electron systems. We have also performed $$^{69,71}$$Ga NMR/NQR studies on a single crystal of PuRhGa$$_5$$. From the temperature dependence of the spin-lattice relaxation rate ($$1/T_1$$), we have found that PuRhGa$$_5$$ is an unconventional superconductor having an anisotropic superconducting (SC) gap 2$$Delta(0)$$=5$$K_BT_c$$. Furthermore, we have confirmed the Knight shift to be decreased below $$T_c$$. This gives strong evidence for spin singlet SC pairing.

Journal Articles

Current status of the control system for J-PARC accelerator complex

Yoshikawa, Hiroshi; Sakaki, Hironao; Sako, Hiroyuki; Takahashi, Hiroki; Shen, G.; Kato, Yuko; Ito, Yuichi; Ikeda, Hiroshi*; Ishiyama, Tatsuya*; Tsuchiya, Hitoshi*; et al.

Proceedings of International Conference on Accelerator and Large Experimental Physics Control Systems (ICALEPCS '07) (CD-ROM), p.62 - 64, 2007/10

J-PARC is a large scale facility of the proton accelerators for the multi-purpose of scientific researches in Japan. This facility consists of three accelerators and three experimental stations. Now, J-PARC is under construction, and LINAC is operated for one year, 3GeV synchrotron has just started the commissioning in this October the 1st. The completion of this facility will be next summer. The control system of accelerators established fundamental performance for the initial commissioning. The most important requirement to the control system of this facility is to minimize the activation of accelerator devices. In this paper, we show that the performances of each layer of this control system have been achieved in the initial stage.

Journal Articles

Anisotropic spin fluctuations and anomalies of nuclear quadrupole interactions in the itinerant antiferromagnet NpCoGa$$_5$$; $$^{59}$$Co NMR and $$^{69,71}$$Ga NMR/NQR studies

Sakai, Hironori; Kambe, Shinsaku; Tokunaga, Yo; Fujimoto, Tatsuya*; Walstedt, R. E.*; Yasuoka, Hiroshi; Aoki, Dai*; Homma, Yoshiya*; Yamamoto, Etsuji; Nakamura, Akio; et al.

Physical Review B, 76(2), p.024410_1 - 024410_14, 2007/07

 Times Cited Count:19 Percentile:62.79(Materials Science, Multidisciplinary)

Nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR)experiments have been performed on a single crystal of NpCoGa$$_5$$ with a N$'e$el temperature $$T_{rm N}$$=47 K. Knight shift, electric field gradient (EFG), frequency, and asymmetry parameter of the EFG are deduced for each site. These parameters are confirmed by NQR measurements in zero field. Hyperfine tensors for each site are deduced. Antiferromagnetic NMR spectra in zero field were also observed. A sharp anisotropy for spin fluctuations in NpCoGa$$_{5}$$ has also been demonstrated.

Journal Articles

Multipolar ordering in NpO$$_2$$ probed by NMR

Tokunaga, Yo; Kambe, Shinsaku; Sakai, Hironori; Fujimoto, Tatsuya*; Ikeda, Shugo; Yamamoto, Etsuji; Nakamura, Akio; Walstedt, R. E.*; Yasuoka, Hiroshi; Homma, Yoshiya*; et al.

Kotai Butsuri, 42(4), p.241 - 252, 2007/04

We have initiated the first NMR measurements in the ordered state of NpO$$_2$$. From the angular dependence of hyperfine fields at $$^{17}$$O nuclei, we have obtained clear evidence for the appearance of field-induced antiferro-octupolar as well as field-induced antiferro-dipolar moments below T$$_0$$=26 K. The NMR studies provide definitive support for the proposed longitudinal triple-q antiferro-octupolar ordering model for NpO$$_2$$.

Journal Articles

NMR observation of quadrupolar order parameter in NpO$$_2$$

Tokunaga, Yo; Aoki, Dai*; Homma, Yoshiya*; Kambe, Shinsaku; Sakai, Hironori; Ikeda, Shugo; Fujimoto, Tatsuya; Walstedt, R. E.*; Yasuoka, Hiroshi; Shiokawa, Yoshinobu*; et al.

Journal of Magnetism and Magnetic Materials, 310(2, Part1), p.735 - 737, 2007/03

In this paper, we present recent and detailed $$^{17}$$O-NMR results obtained in a single crystal. From the analysis of the field-angle dependence of the NMR spectrum,the appearance of a hyperfine interaction with field-induced antiferro-octupole (AFO) moment has been confirmed. This field-induced AFO moment appears as a result of the longitudinal triple-$$vec{q}$$ antiferro-quadrupole (AFQ) structure in the ordered state. We have also observed spin echo modulations caused by quadrupole interactions between the $$^{17}$$O nuclei and the Np-5f quadrupole moments. This reveals that the AFQ structure is directly observable by NMR. Our NMR results provide further insight into the microscopic nature of multipole phase transitions in f-electron systems.

Journal Articles

Enhancement of relaxation rates in the normal state of superconductor PuRhGa$$_5$$:NQR relaxation study

Sakai, Hironori; Kambe, Shinsaku; Tokunaga, Yo; Fujimoto, Tatsuya; Walstedt, R. E.*; Yasuoka, Hiroshi; Aoki, Dai*; Homma, Yoshiya*; Yamamoto, Etsuji; Nakamura, Akio; et al.

Journal of Magnetism and Magnetic Materials, 310(2, Part1), p.e118 - e119, 2007/03

The spin-lattice relaxation rates ($$1/T_1$$) have been measured under zero fieldusing nuclear quadrupole resonance (NQR) linesin superconductor PuRhGa$$_5$$ and Pauli-paramagnet LuCoGa$$_5$$. In the reference LuCoGa$$_5$$ with fully-occupied $$4f$$ shell, the $$1/T_1$$ shows the constant behavior of $$(T_1T)^{-1}=0.495pm0.002$$ (sec$$cdot$$K)$$^{-1}$$. On the other hand, in PuRhGa$$_5$$, $$1/T_1$$ is much larger than in LuCoGa$$_5$$and the $$1/T_1propto T$$ behavior below $$sim$$30 K is seen, where its $$(T_{1}T)^{-1}$$ value is 3.27 $$pm$$ 0.005 (sec$$cdot$$K)$$^{-1}$$. These results suggest a development of coherent Fermi liquid stateincorporated with $$5f$$ electronsbelow $$sim$$30 K in PuRhGa$$_5$$.

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