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Journal Articles

High temperature gas-cooled reactors

Takeda, Tetsuaki*; Inagaki, Yoshiyuki; Aihara, Jun; Aoki, Takeshi; Fujiwara, Yusuke; Fukaya, Yuji; Goto, Minoru; Ho, H. Q.; Iigaki, Kazuhiko; Imai, Yoshiyuki; et al.

High Temperature Gas-Cooled Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.5, 464 Pages, 2021/02

As a general overview of the research and development of a High Temperature Gas-cooled Reactor (HTGR) in JAEA, this book describes the achievements by the High Temperature Engineering Test Reactor (HTTR) on the designs, key component technologies such as fuel, reactor internals, high temperature components, etc., and operational experience such as rise-to-power tests, high temperature operation at 950$$^{circ}$$C, safety demonstration tests, etc. In addition, based on the knowledge of the HTTR, the development of designs and component technologies such as high performance fuel, helium gas turbine and hydrogen production by IS process for commercial HTGRs are described. These results are very useful for the future development of HTGRs. This book is published as one of a series of technical books on fossil fuel and nuclear energy systems by the Power Energy Systems Division of the Japan Society of Mechanical Engineers.

Journal Articles

Bound spinon excitations in the spin-$$frac{1}{2}$$ anisotropic triangular antiferromagnet Ca$$_{3}$$ReO$$_{5}$$Cl$$_{2}$$

Nawa, Kazuhiro*; Hirai, Daigoro*; Kofu, Maiko; Nakajima, Kenji; Murasaki, Ryo*; Kogane, Satoshi*; Kimata, Motoi*; Nojiri, Hiroyuki*; Hiroi, Zenji*; Sato, Taku*

Physical Review Research (Internet), 2(4), p.043121_1 - 043121_11, 2020/12

The spin excitations of the $$S$$ = $$frac{1}{2}$$ anisotropic triangular antiferromagnet Ca$$_{3}$$ReO$$_{5}$$Cl$$_{2}$$ were investigated by inelastic neutron-scattering experiments. The spin excitation spectrum exhibits sharp dispersive modes in addition to a spinonlike continuum. The consistency with the simulated spectrum based on the random-phase approximation is better for Ca$$_{3}$$ReO$$_{5}$$Cl$$_{2}$$ than for Cs$$_{2}$$CuCl$$_{4}$$, indicating that the spin system in the former remains closer to a Tomonaga-Luttinger liquidlike disordered state.

Journal Articles

Magnetic structures and quadratic magnetoelectric effect in LiNiPO$$_{4}$$ beyond 30 T

Fogh, E.*; Kihara, Takumi*; Toft-Petersen, R.*; Bartkowiak, M.*; Narumi, Yasuo*; Prokhnenko, O.*; Miyake, Atsushi*; Tokunaga, Masashi*; Oikawa, Kenichi; S${o}$rensen, M. K.*; et al.

Physical Review B, 101(2), p.024403_1 - 024403_12, 2020/01

 Times Cited Count:5 Percentile:71.61(Materials Science, Multidisciplinary)

Journal Articles

Pulsed magnet system at MLF in J-PARC

Watanabe, Masao; Nojiri, Hiroyuki*

Journal of Neutron Research, 21(1-2), p.39 - 45, 2019/05

Magnetic field acts directly on the spin and the orbital motion of electron in the material and interesting quantum phenomena and phase transition are found in high magnetic field. Recently, experimental equipments using neutron beams in high magnetic field have been rapidly developed. For example, superconducting DC magnet up to 17 T has developed for neutron scattering experiments. Although the sample environment team in the MLF have several DC superconducting magnets up to 7 T as a sample environment apparatus, some users have requested the preparation of higher field magnets. However, another magnet technology is needed to generate higher than 20 T. However, it is difficult to construct such a large system in the MLF from the point of view of construction space. It is practical to employ a pulsed magnetic field as it enables operation of smaller energy as well as downsizing of the instruments. Therefore, we have been developed a compact and movable pulsed magnet system up to 30 T.

Journal Articles

Development of compact high field pulsed magnet system for new sample environment equipment at MLF in J-PARC

Watanabe, Masao; Nojiri, Hiroyuki*; Ito, Shinichi*; Kawamura, Seiko; Kihara, Takumi*; Masuda, Takatsugu*; Sahara, Takuro*; Soda, Minoru*; Takahashi, Ryuta

JPS Conference Proceedings (Internet), 25, p.011024_1 - 011024_5, 2019/03

Recently, neutron scattering experiments have been rapidly progressed under high magnetic field. In the J-PARC, proto-type compact pulse magnet system with the power supply, the coil and the sample stick has been developed. Basic specifications of the power supply are as follows; maximum charged voltage with capacitor is 2 kV, maximum current is 8 kA, repetition rate is a pulse per several minutes and pulse duration is several msec. Maximum magnetic field in the coil is more than 30 Tesla. The sample stick is designed for Orange-Cryostat. In this presentation, We report the details of the pulsed magnet system and the performance of it on neutron scattering experiments at MLF beam line (HRC).

JAEA Reports

Conceptual design of multipurpose compact research reactor; Annual report FY2010 (Joint research)

Imaizumi, Tomomi; Miyauchi, Masaru; Ito, Masayasu; Watahiki, Shunsuke; Nagata, Hiroshi; Hanakawa, Hiroki; Naka, Michihiro; Kawamata, Kazuo; Yamaura, Takayuki; Ide, Hiroshi; et al.

JAEA-Technology 2011-031, 123 Pages, 2012/01

JAEA-Technology-2011-031.pdf:16.08MB

The number of research reactors in the world is decreasing because of their aging. However, the planning to introduce the nuclear power plants is increasing in Asian countries. In these Asian countries, the key issue is the human resource development for operation and management of nuclear power plants after constructed them, and also the necessity of research reactor, which is used for lifetime extension of LWRs, progress of the science and technology, expansion of industry use, human resources training and so on, is increasing. From above backgrounds, the Neutron Irradiation and Testing Reactor Center began to discuss basic concept of a multipurpose low-power research reactor for education and training, etc. This design study is expected to contribute not only to design tool improvement and human resources development in the Neutron Irradiation and Testing Reactor Center but also to maintain and upgrade the technology on research reactors in nuclear power-related companies. This report treats the activities of the working group from July 2010 to June 2011 on the multipurpose low-power research reactor in the Neutron Irradiation and Testing Reactor Center and nuclear power-related companies.

JAEA Reports

Safety demonstration test using the High Temperature Engineering Test Reactor (HTTR); Cold test of the loss of forced cooling

Shinohara, Masanori; Yanagi, Shunki; Tochio, Daisuke; Shimazaki, Yosuke; Nojiri, Naoki; Owada, Hiroyuki; Sato, Nao; Sagawa, Hiroshi; Umeda, Masayuki

JAEA-Technology 2011-029, 39 Pages, 2011/12

JAEA-Technology-2011-029.pdf:3.03MB

JAEA plans and performs the safety demonstration test using the HTTR to develop High Temperature Gas Reactor technologies. Cold test of the loss of forced cooling was conducted prior to the safety demonstration test, to check test procedure and plant behavior. Cold test consists of two phases, Phase1, 1 or 2 Vessel Cooling System (VCS) terminates, in the Phase2, all 3 Gas circulators and 1 VCS terminates. Cold test could confirm test process, and obtain data necessary to analysis and 2-dimensional horizontal sectional model analysis was verified to simulate actual measurement value.

Journal Articles

Resonant magnetic X-ray diffraction study on the successive metamagnetic transitions of TbB$$_4$$ up to 30T

Inami, Toshiya; Owada, Kenji; Matsuda, Yasuhiro*; Ouyang, Z. W.*; Nojiri, Hiroyuki*; Matsumura, Takeshi*; Okuyama, Daisuke*; Murakami, Yoichi*

Journal of Physics; Conference Series, 211, p.012010_1 - 012010_6, 2010/02

 Times Cited Count:3 Percentile:78.42

Journal Articles

Universal magnetic structure of the half-magnetization phase in Cr-based spinels

Matsuda, Masaaki; Oyama, Kenji*; Yoshii, Shunsuke*; Nojiri, Hiroyuki*; Frings, P.*; Duc, F.*; Vignolle, B.*; Rikken, G. L. J. A.*; Regnault, L.-P.*; Lee, S.-H.*; et al.

Physical Review Letters, 104(4), p.047201_1 - 047201_4, 2010/01

 Times Cited Count:23 Percentile:75.89(Physics, Multidisciplinary)

Journal Articles

Instability of magnons in two-dimensional antiferromagnets at high magnetic fields

Masuda, Takatsugu*; Kitaoka, Shuji*; Takamizawa, Satoshi*; Metoki, Naoto; Kaneko, Koji; Rule, K. C.*; Kiefer, K.*; Manaka, Hiroshi*; Nojiri, Hiroyuki*

Physical Review B, 81(10), p.100402_1 - 100402_4, 2010/00

 Times Cited Count:37 Percentile:81.27(Materials Science, Multidisciplinary)

Spin dynamics of the square lattice Heisenberg antiferromagnet, Ba$$_2$$MnGe$$_2$$O$$_7$$, is studied by a combination of bulk measurements, neutron diffraction, and inelastic neutron-scattering techniques. Easy plane type antiferromagnetic order is identified at T$$leq$$4.0 K. The exchange interactions are estimated as $$J_1$$ = 27.8(3) $$mu$$eV and$$J_2$$ = 1.0(1) $$mu$$eV, and the saturation field $$H$$$$_{rm C}$$ is 9.75 T. Magnetic excitation measurements with high experimental resolution setup by triple axis neutron spectrometer reveals the instability of one magnon excitation in the field range of 0.7$$H$$$$_{rm C}$$ $$_sim^{<}$$ $$H$$ $$_sim^{<}$$ 0.85$$H$$$$_{rm C}$$.

Journal Articles

XMCD spectroscopy on valence fluctuating and heavy fermion compounds in very high magnetic fields up to 40 T

Matsuda, Yasuhiro*; Her, J. L.*; Inami, Toshiya; Owada, Kenji; Ouyang, Z. W.*; Okada, Kyoko*; Nojiri, Hiroyuki*; Mitsuda, Akihiro*; Wada, Hirofumi*; Yoshimura, Kazuyoshi*; et al.

Journal of Physics; Conference Series, 190, p.012019_1 - 012019_6, 2009/11

 Times Cited Count:7 Percentile:86.65

Journal Articles

X-ray magnetic circular dichroism of a valence fluctuating state in Eu at high magnetic fields

Matsuda, Yasuhiro*; Ouyang, Z. W.*; Nojiri, Hiroyuki*; Inami, Toshiya; Owada, Kenji; Suzuki, Motohiro*; Kawamura, Naomi*; Mitsuda, Akihiro*; Wada, Hirofumi*

Physical Review Letters, 103(4), p.046402_1 - 046402_4, 2009/07

 Times Cited Count:49 Percentile:87.39(Physics, Multidisciplinary)

X-ray magnetic circular dichroism (XMCD) at the Eu L edge in two compounds exhibiting valence fluctuation, namely EuNi$$_2$$(Si$$_{0.18}$$Ge$$_{0.82}$$)$$_2$$ and EuNi$$_2$$P$$_2$$, has been investigated at high magnetic fields of up to 40T. A distinct XMCD peak corresponding to the trivalent state (Eu$$^{3+}$$), whose ground state is nonmagnetic (J = 0), was observed in addition to the main XMCD peak corresponding to the magnetic (J = 7/2) divalent state (Eu$$^{2+}$$). This result indicates that the 5$$d$$ electrons belonging to both valence states are magnetically polarized. It was also found that the ratio $$P$$$$_{5d}$$(3+)/$$P$$$$_{5d}$$(2+) between the polarization of 5$$d$$ electrons($$P$$$$_{5d}$$) in the Eu$$^{3+}$$ state and that of Eu$$^{2+}$$ depends on the material. The possible origin of the XMCD and an explanation of the material dependence of $$P$$$$_{5d}$$(3+)/$$P$$$$_{5d}$$(2+) are discussed in terms of hybridization between the conduction electrons and the f electrons.

JAEA Reports

Handling of HTTR second driver fuel elements in assembling and storage working

Tomimoto, Hiroshi; Kato, Yasushi; Owada, Hiroyuki; Sato, Nao; Shimazaki, Yosuke; Kozawa, Takayuki; Shinohara, Masanori; Hamamoto, Shimpei; Tochio, Daisuke; Nojiri, Naoki; et al.

JAEA-Technology 2009-025, 29 Pages, 2009/06

JAEA-Technology-2009-025.pdf:21.78MB

The first driver fuel of the HTTR (High Temperature Engineering test Reactor) was loaded in 1998 and the HTTR reached first criticality state in the same year. The HTTR has been operated using the first driver fuel for a decade. In Fuel elements assembling, 4770 of fuel rods which consist of 12 kinds of enrichment uranium are loaded into 150 fuel graphite blocks for HTTR second driver fuel elements. Measures of prevention of fuel rod miss loading, are employed in fuel design. Additionally, precaution of fuel handling on assembling are considered. Reception of fuel rods, assembling of fuel elements and storage of second driver fuels in the fresh fuel storage rack in the HTTR were started since June, 2008. Assembling, storage and pre-service inspection were divided into three parts. The second driver fuel assembling was completed in September, 2008. This report describes concerns of fuel handling on assembling and storage work for the HTTR fuel elements.

JAEA Reports

Result of long-term operation of HTTR; Rated/parallel-loaded 30-days operation

Tochio, Daisuke; Nojiri, Naoki; Hamamoto, Shimpei; Inoi, Hiroyuki; Sekita, Kenji; Kondo, Masaaki; Saikusa, Akio; Kameyama, Yasuhiko; Saito, Kenji; Fujimoto, Nozomu

JAEA-Technology 2009-005, 47 Pages, 2009/05

JAEA-Technology-2009-005.pdf:4.01MB

HTTR is now conducted in-service operation through the rise-to power operation with rated operation or high-temperature test operation from achievement of first criticality at 1998. In order to demonstrate to supply stable heat to heat utilization system for long-term, HTTR was conducted rated/parallel-loaded 30-days operation. This paper reports the characteristics of long-term operation for HTTR.

Journal Articles

Resonant magnetic X-ray diffraction study on successive metamagnetic transitions in TbB$$_4$$

Inami, Toshiya; Owada, Kenji; Matsuda, Yasuhiro*; Ouyang, Z. W.*; Nojiri, Hiroyuki*; Matsumura, Takeshi*; Okuyama, Daisuke*; Murakami, Yoichi*

Journal of the Physical Society of Japan, 78(3), p.033707_1 - 033707_4, 2009/03

 Times Cited Count:15 Percentile:66.43(Physics, Multidisciplinary)

Journal Articles

The Frontiers of condensed matter science advanced by J-PARC

Fujii, Yasuhiko; Arai, Masatoshi; Kadono, Ryosuke*; Kanaya, Toshiji*; Kamiyama, Takashi*; Niimura, Nobuo*; Nojiri, Hiroyuki*; Noda, Yukio*; Yagi, Takehiko*; Yamada, Kazuyoshi*

Kotai Butsuri, 43(7), p.441 - 450, 2008/07

no abstracts in English

JAEA Reports

Ultrasonic test results for the reactor pressure vessel of the HTTR; Longitudinal welding line of bottom dome

Nojiri, Naoki; Owada, Hiroyuki; Kato, Yasushi

JAEA-Technology 2008-045, 38 Pages, 2008/06

JAEA-Technology-2008-045.pdf:6.95MB

This paper describes the inspection method, the measured area, etc. of the ultrasonic test of the in-service inspection (ISI) for welding lines of the reactor pressure vessel of the HTTR and the inspection results of the longitudinal welding line of the bottom dome. The pre-service inspection (PSI) results for estimation of occurrence and progression of defects to compare the ISI results is described also.

Journal Articles

High-magnetic-field X-ray absorption spectroscopy of field-induced valence transition in EuNi$$_2$$(Si$$_{1-x}$$Ge$$_x$$)$$_2$$

Matsuda, Yasuhiro*; Inami, Toshiya; Owada, Kenji; Murata, Yuto*; Nojiri, Hiroyuki*; Murakami, Yoichi*; Mitsuda, Akihiro*; Wada, Hirofumi*; Miyazaki, Hiroshi*; Harada, Isao*

Journal of the Physical Society of Japan, 77(5), p.054713_1 - 054713_7, 2008/05

 Times Cited Count:24 Percentile:75.23(Physics, Multidisciplinary)

The magnetic-field-induced valence transition in EuNi$$_2$$(Si$$_{1-x}$$Ge$$_x$$)$$_2$$ (x=0.82, 0.85) has been studied by X-ray absorption spectroscopy at low temperatures. The field dependence of the Eu valence is directly observed for the first time. We find a significant decrease in the valences at high magnetic fields above 40 T. The valence of Eu changes from v = 2.75 at a zero field to v = 2.33 at 40 T for x = 0.82. The results are analyzed using a theoretical model. The hybridization parameter V between the Eu$$^{2+}$$ and Eu$$^{3+}$$ states and the energy separation $$Delta$$$$E$$ are determined, which are crucial for quantum mechanical mixing.

Journal Articles

Direct observation of field-induced variant transformation in Fe$$_3$$Pt using pulsed magnetic field X-ray diffraction

Ouyang, Z. W.*; Matsuda, Yasuhiro*; Nojiri, Hiroyuki*; Inami, Toshiya; Owada, Kenji; Tsubota, Masami*; Sakon, Takuo*; Fukuda, Takashi*; Kakeshita, Tomoyuki*

Journal of Applied Physics, 102(11), p.113917_1 - 113917_6, 2007/12

 Times Cited Count:1 Percentile:5.73(Physics, Applied)

JAEA Reports

HTTR operation data base, 2; Examples of the HTTR core characteristics data base, etc

Nojiri, Naoki; Owada, Hiroyuki; Fujimoto, Nozomu

JAEA-Data/Code 2007-013, 93 Pages, 2007/06

JAEA-Data-Code-2007-013.pdf:5.34MB

For the future HTGR development and the management of the High Temperature engineering Test Reactor(HTTR), the HTTR operation data base is constructed. The data base consists of the sorted or evaluated data based on the measured values from the HTTR's operation, such as excess reactivity of the core, temperature at facilities of the core and the plant, impurities in coolant and so on. The data base also consists of some sub-databases which have objects related to the future HTGR development or the HTTR's operational management in order to manage the important operation data systematically on a long term. This paper describes examples of the HTTR common data base, the HTTR nuclear characteristics data base, the helium purity control data base and the other data base.

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