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Journal Articles

Quantum dynamics of hydrogen in the iron-based superconductor LaFeAsO$$_{0.9}$$D$$_{0.1}$$ measured with inelastic neutron spectroscopy

Yamaura, Junichi*; Hiraka, Haruhiro*; Iimura, Soshi*; Muraba, Yoshinori*; Bang, J.*; Ikeuchi, Kazuhiko*; Nakamura, Mitsutaka; Inamura, Yasuhiro; Honda, Takashi*; Hiraishi, Masatoshi*; et al.

Physical Review B, 99(22), p.220505_1 - 220505_6, 2019/06

Inelastic neutron scattering was performed for an iron-based superconductor, where most of D (deuterium) replaces oxygen, while a tiny amount goes into interstitial sites. By first-principle calculation, we characterize the interstitial sites for D (and for H slightly mixed) with four equivalent potential minima. Below the superconducting transition temperature Tc = 26 K, new excitations emerge in the range 5-15 meV, while they are absent in the reference system LaFeAsO$$_{0.9}$$F$$_{0.1}$$. The strong excitations at 14.5 meV and 11.1 meV broaden rapidly around 15 K and 20 K, respectively, where each energy becomes comparable to twice of the superconducting gap. The strong excitations are ascribed to a quantum rattling, or a band motion of hydrogen, which arises only if the number of potential minima is larger than two.

Journal Articles

Introduction and implementation of physical protection measures including trustworthiness program at Tokai Reprocessing Facilities

Nakamura, Hironobu; Kimura, Takashi; Yamazaki, Katsuyuki; Kitao, Takahiko; Tasaki, Takashi; Iida, Toru

Proceedings of International Conference on Physical Protection of Nuclear Material and Nuclear Facilities (Internet), 9 Pages, 2018/09

After the accident of Fukushima Daiichi Nuclear Power Station, to develop effective security measures based on the lesson learned from such crisis and to meet the IAEA Nuclear Security Recommendations (INFCIRC/225/Rev.5), NRA in Japan made a partial amendment of the regulations concerning the reprocessing activity in 2012. The Tokai reprocessing facility implemented all of those security measures by the end of March 2014. Those new measures help us to keep high degree of security level and contributed to our planned operations to reduce the potential risk of the plant. On the other hand, the trustworthiness program was newly introduced in 2016, based on the trustworthiness policy determined by NRA. The implementing entity of the program is JAEA for the Tokai Reprocessing Facility and is required for both the persons afford unescorted access to Category I and II, CAS/SAS, and the persons afford access to the sensitive information. Those who are involved this program will be judged before engaging the work whether they might act as insider to cause or assist radiological sabotage or unauthorized removal of nuclear material, or leak sensitive information. The program is expected as a measure against insider at reprocessing facilities, and is expected to be enforced around the autumn of 2017. As well as the establishment of security measures, the promoting nuclear security culture for all employees was a big challenge. The Tokai reprocessing facility have introduced several security culture activities, such as case study education of security events done by a small group and putting up the security culture poster and so on. This paper presents introduction and implementation with effectiveness of security measures in the Tokai reprocessing facilities and the future security measures applied to the reprocessing facilities are discussed.

Journal Articles

Some characteristics of gas-liquid two-phase flow in vertical large-diameter channels

Shen, X.*; Schlegel, J. P.*; Hibiki, Takashi*; Nakamura, Hideo

Nuclear Engineering and Design, 333, p.87 - 98, 2018/07

 Times Cited Count:1 Percentile:62.02(Nuclear Science & Technology)

Journal Articles

Discussion of effective insider threat mitigation method at reprocessing plant

Nakamura, Hironobu; Kitao, Takahiko; Yamada, Hiroyuki; Kono, Soma; Kimura, Takashi; Tasaki, Takashi

Proceedings of INMM 59th Annual Meeting (Internet), 9 Pages, 2018/07

Journal Articles

Elastic and dynamical structural properties of La and Mn-doped SrTiO$$_{3}$$ studied by neutron scattering and their relation with thermal conductivities

Kajimoto, Ryoichi; Nakamura, Mitsutaka; Murai, Naoki; Shamoto, Shinichi; Honda, Takashi*; Ikeda, Kazutaka*; Otomo, Toshiya*; Hata, Hiroto*; Eto, Takahiro*; Noda, Masaaki*; et al.

Scientific Reports (Internet), 8(1), p.9651_1 - 9651_8, 2018/06

 Times Cited Count:2 Percentile:41.94(Multidisciplinary Sciences)

Journal Articles

Neutron scattering study of yttrium iron garnet

Shamoto, Shinichi; Ito, Takashi; Onishi, Hiroaki; Yamauchi, Hiroki; Inamura, Yasuhiro; Matsuura, Masato*; Akatsu, Mitsuhiro*; Kodama, Katsuaki; Nakao, Akiko*; Moyoshi, Taketo*; et al.

Physical Review B, 97(5), p.054429_1 - 054429_9, 2018/02

 Times Cited Count:1 Percentile:100(Materials Science, Multidisciplinary)

Nuclear and magnetic structure and full magnon dispersions of yttrium iron garnet Y$$_3$$Fe$$_5$$O$$_{12}$$ have been studied by neutron scattering. The lowest-energy dispersion below 14 meV exhibits a quadratic dispersion as expected from ferromagnetic magnons. The imaginary part of $$q$$-integrated dynamical spin susceptibility $$chi$$"($$E$$) exhibits a square-root energy-dependence in the low energies. The magnon density of state is estimated from the $$chi$$"($$E$$) obtained on an absolute scale. The value is consistent with a single chirality mode for the magnon branch expected theoretically.

Journal Articles

Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex, 2; Neutron scattering instruments

Nakajima, Kenji; Kawakita, Yukinobu; Ito, Shinichi*; Abe, Jun*; Aizawa, Kazuya; Aoki, Hiroyuki; Endo, Hitoshi*; Fujita, Masaki*; Funakoshi, Kenichi*; Gong, W.*; et al.

Quantum Beam Science (Internet), 1(3), p.9_1 - 9_59, 2017/12

The neutron instruments suite, installed at the spallation neutron source of the Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex (J-PARC), is reviewed. MLF has 23 neutron beam ports and 21 instruments are in operation for user programs or are under commissioning. A unique and challenging instrumental suite in MLF has been realized via combination of a high-performance neutron source, optimized for neutron scattering, and unique instruments using cutting-edge technologies. All instruments are/will serve in world-leading investigations in a broad range of fields, from fundamental physics to industrial applications. In this review, overviews, characteristic features, and typical applications of the individual instruments are mentioned.

JAEA Reports

Inspection and repair techniques in reactor vessel of the experimental fast reactor JOYO; Development of devices for retrieving bent MARICO-2 subassembly and completion of retrieval work

Ashida, Takashi; Nakamura, Toshiyuki*; Ito, Hideaki

JAEA-Technology 2017-024, 198 Pages, 2017/11

JAEA-Technology-2017-024.pdf:55.8MB
JAEA-Technology-2017-024-appendix(CD-ROM)-1.zip:298.09MB
JAEA-Technology-2017-024-appendix(CD-ROM)-2.zip:210.77MB

In the experimental fast reactor Joyo, the disconnecting of an irradiation test subassembly MARICO-2 (Material Testing Irradiation Rig with Temperature Control) from its holding mechanism was conducted in May 2007. After the operation, the rotating plug was rotated despite the fact that the test subassembly was not disconnected completely. Consequently, top of wrapper tube of the MARICO-2 subassembly was bent onto the in-vessel storage rack. Since the overhanging part of the subassembly was in the height in which contacts with the upper core structure, it had damaged the bottom surface of the upper core structure. As the result, it was necessary to replace the damaged upper core structure and to retrieve the bent MARICO-2 subassembly for Joyo restart. Retrieval devices for MARICO-2 subassembly consist of a gripper mechanism to lift subassembly together with transfer pot, a guide tube built-in a pantograph mechanism to adjust lifting axis and safety mechanisms to prevent or mitigate falling of MARICO-2 subassembly, a retrieval cask and so on. Design of the retrieval devices have been verified in ex-vessel partial or full-scale mock-up tests and in-vessel function tests. In 2014, MARICO-2 subassembly was successfully retrieved from the reactor vessel by applying these retrieval devices. Then, retrieved subassembly was transported to a hot-cell facility for post-irradiation examinations. Devices have demonstrated expected performance under the actual environmental conditions of a sodium cooled fast reactor. This is a synthetic report about the retrieval work of the deformed and irradiated test subassembly in Joyo. This report includes the detail design and fabrication of the special retrieval device, results of tests for confirmation including the mock-up tests in manufacturer's factory, and results of MARICO-2 retrieval work from the reactor vessel.

Journal Articles

Experimental study on interfacial area transport of two-phase bubbly flow in a vertical large-diameter square duct

Shen, X.*; Sun, Haomin; Deng, B.*; Hibiki, Takashi*; Nakamura, Hideo

International Journal of Heat and Fluid Flow, 67(Part.A), p.168 - 184, 2017/10

An experimental study on upward bubbly air-water flows in a vertical large-diameter square duct have been performed by mainly using four-sensor probes. Local measurements of interfacial area concentration (IAC), void fraction, 3D bubble velocity vector and bubble diameter at 3 axial positions were conducted. Although the interfacial area transport equation (IATE) and its bubble coalescence and breakup models have already played an important role in predicting the IAC in general two-phase flow fields, they are mainly developed based on the two-phase flow experimental data taken in round pipes or small diameter channels. To confirm their usability in large-diameter square duct, this study has evaluated the 1D one-group IATE with its 6 sets of bubble coalescence and breakup models with the presently-obtained database. It was found the relative error between the best prediction and the database was 25%.

Journal Articles

Experimental analysis of neutron and background $$gamma$$-ray energy spectra of 80-400 MeV $$^{7}$$Li(p,n) reactions under the quasi-monoenergetic neutron field at RCNP, Osaka University

Iwamoto, Yosuke; Sato, Tatsuhiko; Satoh, Daiki; Hagiwara, Masayuki*; Yashima, Hiroshi*; Masuda, Akihiko*; Matsumoto, Tetsuro*; Iwase, Hiroshi*; Shima, Tatsushi*; Nakamura, Takashi*

EPJ Web of Conferences (Internet), 153, p.08019_1 - 08019_3, 2017/09

 Percentile:100

To develop 100-400 MeV quasi-monoenergetic neutron field, we measured neutron and unexpected $$gamma$$-ray energy spectra of the $$^{7}$$Li(p,n) reaction with 80-389 MeV protons in the 100-m time-of-flight (TOF) tunnel at the Research Center for Nuclear Physics (RCNP). Neutron energy spectra with energies above 3 MeV were measured by the TOF method and $$gamma$$ energy spectra with energies above 0.1 MeV were measured by the automatic unfolding function of the radiation dose monitor DARWIN. For neutron spectra, the contribution of peak intensity to the total intensity integrated with energies above 3 MeV varied between 0.38 and 0.48. For $$gamma$$-ray spectra, high-energetic $$gamma$$-rays at around 70 MeV originated from the decay of $$pi$$$$^{0}$$ were observed over 200 MeV. For the 246-MeV proton incident reaction, the contribution of $$gamma$$-ray dose to neutron dose is negligible because the ratio of $$gamma$$-ray to neutron is 0.014.

Journal Articles

Characterization of the PTW 34031 ionization chamber (PMI) at RCNP with high energy neutrons ranging from 100 - 392 MeV

Theis, C.*; Carbonez, P.*; Feldbaumer, E.*; Forkel-Wirth, D.*; Jaegerhofer, L.*; Pangallo, M.*; Perrin, D.*; Urscheler, C.*; Roesler, S.*; Vincke, H.*; et al.

EPJ Web of Conferences (Internet), 153, p.08018_1 - 08018_5, 2017/09

 Percentile:100

At CERN, gas-filled ionization chambers PTW-34031 (PMI) are commonly used in radiation fields including neutrons, protons and $$gamma$$-rays. A response function for each particle is calculated by the radiation transport code FLUKA. To validate a response function to high energy neutrons, benchmark experiments with quasi mono-energetic neutrons have been carried out at RCNP, Osaka University. For neutron irradiation with energies below 200 MeV, very good agreement was found comparing the FLUKA simulations and the measurements. In addition it was found that at proton energies of 250 and 392 MeV, results calculated with neutron sources underestimate the experimental data due to a non-negligible gamma component originating from the target $$^{7}$$Li(p,n)Be reaction.

Journal Articles

Shielding experiments of concrete and iron for the 244 MeV and 387 MeV quasi-mono energetic neutrons using a Bonner sphere spectrometer (at RCNP, Osaka Univ.)

Matsumoto, Tetsuro*; Masuda, Akihiko*; Nishiyama, Jun*; Iwase, Hiroshi*; Iwamoto, Yosuke; Satoh, Daiki; Hagiwara, Masayuki*; Yashima, Hiroshi*; Yashima, Hiroshi*; Shima, Tatsushi*; et al.

EPJ Web of Conferences (Internet), 153, p.08016_1 - 08016_3, 2017/09

 Percentile:100

Neutron energy spectra behind concrete and iron shields were measured for quasi-monoenergetic neutrons above 200 MeV using a Bonner sphere spectrometer (BSS). Quasi-monoenergetic neutrons were produced by the $$^{7}$$Li(p,xn) reaction with 246-MeV and 389-MeV protons. The response function of BSS was also measured at neutron energies from 100 MeV to 387 MeV. In data analysis, the measured response function was used and the multiple neutron scattering effect between the BSS and the shielding material was considered. The neutron energy spectra behind the concrete and iron shields were obtained by the unfolding method using the MAXED code. Ambient dose equivalents were obtained as a function of a shield thickness successfully. For the case of the 244 MeV neutron incidence, the multiple neutron scattering effect on the effective dose is large under 50 cm thickness of the concrete shield.

Journal Articles

Neutron spectrometry and dosimetry in 100 and 300 MeV quasi-mono-energetic neutron field at RCNP, Osaka University, Japan

Mares, V.*; Trinkl, S.*; Iwamoto, Yosuke; Masuda, Akihiko*; Matsumoto, Tetsuro*; Hagiwara, Masayuki*; Satoh, Daiki; Yashima, Hiroshi*; Shima, Tatsushi*; Nakamura, Takashi*

EPJ Web of Conferences (Internet), 153, p.08020_1 - 08020_3, 2017/09

 Times Cited Count:1 Percentile:14.04

To validate response of an extended range Bonner Sphere Spectrometer (ERBSS) with $$^{3}$$He proportional counter, neutron energy spectra were measured using an ERBSS in the quasi-mono-energetic neutron field at the Research Center for Nuclear Physics (RCNP). Using 100 MeV and 296 MeV proton beams, neutron fields with nominal peak energies of 96 MeV and 293 MeV were generated via $$^{7}$$Li(p,n)$$^{7}$$Be reactions. The energy spectra were measured at a distance of 35 m from the target. To deduce the corresponding neutron spectra from thermal to the nominal maximum energy, the ERBSS data were unfolded using the MSANDB unfolding code. At high energies, the neutron spectra were also measured by means of the TOF method using NE213 organic liquid scintillators. The agreement between ERBSS and TOF neutron spectra above 5 MeV is very good. Comparison in terms of ambient dose equivalent, H$$^{*}$$(10) between ERBSS and TOF values for both proton energies shows very good agreement.

Journal Articles

Axial flow characteristics of bubbly flow in a vertical large-diameter square duct

Shen, X.*; Sun, Haomin; Deng, B.*; Hibiki, Takashi*; Nakamura, Hideo

Proceedings of 17th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-17) (USB Flash Drive), 14 Pages, 2017/09

An experimental study on the upward bubbly air-water flows in a vertical large-diameter square duct have been performed by using four-sensor probes. The four-sensor probe were applied in the local measurements at 3 axial positions along the flow direction to obtain interfacial area concentration, 3-D bubble velocity vector and bubble diameter. The obtained void fraction, interfacial area concentration, 3-D bubble velocity vector and bubble diameter provided valuable insight into the flow structure and will serve as a valuable database to develop the mechanistic models for interfacial area transport equation sources and sinks.

Journal Articles

Materials and Life Science Experimental Facility at the Japan Proton Accelerator Research Complex, 3; Neutron devices and computational and sample environments

Sakasai, Kaoru; Sato, Setsuo*; Seya, Tomohiro*; Nakamura, Tatsuya; To, Kentaro; Yamagishi, Hideshi*; Soyama, Kazuhiko; Yamazaki, Dai; Maruyama, Ryuji; Oku, Takayuki; et al.

Quantum Beam Science (Internet), 1(2), p.10_1 - 10_35, 2017/09

Neutron devices such as neutron detectors, optical devices including supermirror devices and $$^{3}$$He neutron spin filters, and choppers are successfully developed and installed at the Materials Life Science Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC), Tokai, Japan. Four software components of MLF computational environment, instrument control, data acquisition, data analysis, and a database, have been developed and equipped at MLF. MLF also provides a wide variety of sample environment options including high and low temperatures, high magnetic fields, and high pressures. This paper describes the current status of neutron devices, computational and sample environments at MLF.

Journal Articles

Multi-dimensional gas-liquid two-phase flow in vertical large-diameter channels

Shen, X.*; Schlegel, J. P.*; Hibiki, Takashi*; Nakamura, Hideo

Proceedings of 2017 Japan-US Seminar on Two-Phase Flow Dynamics (JUS 2017), 6 Pages, 2017/06

Journal Articles

2016 Professional Engineer (PE) test preparation course; Nuclear and radiation technical disciplines

Takahashi, Naoki; Suzuki, Soju; Saito, Hiroto; Ueno, Takashi; Abe, Sadayoshi; Yamanaka, Atsushi; Tanigawa, Masafumi; Nakamura, Daishi; Sasaki, Shunichi; Mine, Tadaharu

Nippon Genshiryoku Gakkai Homu Peji (Internet), 20 Pages, 2017/05

no abstracts in English

Journal Articles

Development and implementation of GloveBox Cleanout Assistance Tool (BCAT) to detect the presence of MOX by computational approach

Nakamura, Hironobu; Nakamichi, Hideo; Mukai, Yasunobu; Hosoma, Takashi; Kurita, Tsutomu; LaFleur, A. M.*

Proceedings of International Conference on Mathematics & Computational Methods Applied to Nuclear Science & Engineering (M&C 2017) (USB Flash Drive), 7 Pages, 2017/04

In order to maintain facility nuclear material accountancy (NMA) and safeguards properly, to understand where and how much holdup deposit in the process is presence is very important for the cleanout before PIT. JAEA and LANL developed a GloveBox Cleanout Assistance Tool (BCAT) to help cleanout (MOX powder recovering in a glovebox) for invisible holdup effectively by computational approach which is called distributed source-term approach (DSTA). The BCAT tool is a simple neutron measurement slab detectors and helps operator to find locations of holdup. To know the holdup location and the activity from the neutron measurements, the relation between BCAT measurements results at predetermined positions (57 positions) and source voxels (53 voxels) that we want to know the holdup activity was mathematically defined as a matrix by the MCNPX simulation. The model of MCNPX for entire process is very precisely established. We have implemented and experimentally proved that the BCAT tool can direct the operator to recoverable holdup that would otherwise be accounted for as MUF. Reducing facility MUF results in a direct improvement of the facility NMA. The BCAT enables the staff to significantly improve their knowledge of the locations of residual holdup in the process area. JAEA would like to use this application for dismantling of the glovebox with transparency in the future.

Journal Articles

Applicability of the two-angle differential method to response measurement of neutron-sensitive devices at the RCNP high-energy neutron facility

Masuda, Akihiko*; Matsumoto, Tetsuro*; Iwamoto, Yosuke; Hagiwara, Masayuki*; Satoh, Daiki; Sato, Tatsuhiko; Iwase, Hiroshi*; Yashima, Hiroshi*; Nakane, Yoshihiro; Nishiyama, Jun*; et al.

Nuclear Instruments and Methods in Physics Research A, 849, p.94 - 101, 2017/03

 Percentile:100(Instruments & Instrumentation)

Quasi-monoenergetic high-energy neutron fields induced by $$^{7}$$Li(p,n) reactions are used for the response evaluation of neutron-sensitive devices. The quasi-monoenergetic high-energy field consists of high-energy monoenergetic peak neutrons and unwanted continuum neutrons down to the low-energy region. A two-angle differential method has been developed to compensate for the effect of the continuum neutrons in the response measurements. In this study, the two-angle differential method was demonstrated for Bonner sphere detectors, which are typical examples of moderator-based neutron-sensitive detectors, to investigate the method's applicability and its dependence on detector characteristics. Through this study, the adequacy of the two-angle differential method was experimentally verified, and practical suggestions were made pertaining to this method.

Journal Articles

Evaluation of mechanical properties of oxide layers of fuel cladding material Zircaloy-4 and M5 oxidized under PWR condition using Nano indentation with spherical indenter

Shibata, Akira; Wakui, Takashi; Nakamura, Natsuki; Futakawa, Masatoshi; Maekawa, Katsuhiro*; Naka, Michihiro

Zairyo Shiken Gijutsu, 62(1), p.41 - 47, 2017/01

Nuclear reactor fuel cladding material has been gradually replaced from Zircaloy-4 to Zr-Nb alloys such as M5. To reveal the origin of good corrosion resistance of Zr-Nb alloys, evaluation on oxide layer of fuel cladding tube Zircaloy-4 and M5 was performed. Nano-indentation with spherical indenter was performed on oxide layer of those materials. Test results of the indentation were evaluated by the inverse analysis using Kalman filter and Finite Element Method. The results analysis shows that the oxide layer of M5 has more ductility compare from that of Zircaloy 4. Thus, oxide layer of Zircaloy4 could be injured by smaller strain compare from that of M5.

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