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Journal Articles

Impacts of friction stir processing on irradiation effects in vacuum-plasma-spray coated tungsten

Ozawa, Kazumi; Tanigawa, Hiroyasu; Morisada, Yoshiaki*; Fujii, Hidetoshi*

Fusion Engineering and Design, 98-99, p.2054 - 2057, 2015/10

 Times Cited Count:1 Percentile:86.4(Nuclear Science & Technology)

Reduced activation ferritic/martensitic steel, as typified by F82H, is a promising candidate for structural material of DEMO fusion reactors. To prevent plasma sputtering, tungsten (W) coating was essentially required. This study aims to examine the irradiation effects on hardness and microstructure of vacuum-plasma-spray coated W-F82H steel, with a special emphasis on the impacts of grain-refining induced by frictional stir processing (FSP). It was revealed that the hardness of the VPS-FSP W after ion-irradiation to 5.4 dpa at 800$$^{circ}$$C were not remarkably changed, where bulk W usually exhibited significant irradiation hardening.

Journal Articles

Modification of vacuum plasma sprayed tungsten coating on reduced activation ferritic/martensitic steels by friction stir processing

Tanigawa, Hiroyasu; Ozawa, Kazumi; Morisada, Yoshiaki*; Noh, S.*; Fujii, Hidetoshi*

Fusion Engineering and Design, 98-99, p.2080 - 2084, 2015/10

 Times Cited Count:7 Percentile:33.59(Nuclear Science & Technology)

The vacuum plasma spray (VPS) technique has been investigated as the most practical method to form Tungsten (W) layer as a plasma facing material in fusion devices. The issues are the thermal conductivity and the strength of VPS-W, i.e., the thermal conductivity of VPS-W were significantly lower than that of the bulk W, and the hardness of VPS-W is much less than that of the bulk W. These are mainly caused by the porous structure of VPS-W. In order to solve these issues, friction stir processing (FPS) was applied on VPS-W in this study. It was suggested that FSP can contribute to significant improvement both in mechanical and thermal properties of VPS-W coating.

Journal Articles

Cross section measurements of the radioactive $$^{107}$$Pd and stable $$^{105,108}$$Pd nuclei at J-PARC/MLF/ANNRI

Nakamura, Shoji; Kimura, Atsushi; Kitatani, Fumito; Ota, Masayuki; Furutaka, Kazuyoshi; Goko, Shinji*; Hara, Kaoru; Harada, Hideo; Hirose, Kentaro; Kin, Tadahiro*; et al.

Nuclear Data Sheets, 119, p.143 - 146, 2014/05

 Times Cited Count:7 Percentile:44.79(Physics, Nuclear)

We have started the measurements of the neutron-capture cross sections for stable $$^{105,108}$$Pd nuclei as well as the radioactive $$^{107}$$Pd. The neutron-capture cross-section measurements by the time-of flight method were performed using an apparatus called "Accurate Neutron-Nucleus Reaction measurement Instrument (ANNRI)" installed at the neutron Beam Line No.4 of the Materials and Life science experimental Facility (MLF) in the J-PARC. The neutron-capture cross sections of $$^{107}$$Pd and $$^{105,108}$$Pd have been measured in the neutron energy range from thermal to 300 eV. Some new information was obtained for resonances of these Pd nuclei.

Journal Articles

Capture cross-section measurement of $$^{241}$$Am(n,$$gamma$$) at J-PARC/MLF/ANNRI

Harada, Hideo; Ota, Masayuki; Kimura, Atsushi; Furutaka, Kazuyoshi; Hirose, Kentaro; Hara, Kaoru; Kin, Tadahiro*; Kitatani, Fumito; Koizumi, Mitsuo; Nakamura, Shoji; et al.

Nuclear Data Sheets, 119, p.61 - 64, 2014/05

 Times Cited Count:18 Percentile:18.34(Physics, Nuclear)

Journal Articles

Neutron capture cross section of palladium-107 in the thermal-neutron energy region

Nakamura, Shoji; Ota, Masayuki; Oshima, Masumi; Kitatani, Fumito; Kimura, Atsushi; Kin, Tadahiro; Koizumi, Mitsuo; Goko, Shinji*; Toh, Yosuke; Hara, Kaoru; et al.

JAEA-Conf 2012-001, p.147 - 152, 2012/07

Journal Articles

Neutron-capture cross-sections of $$^{244}$$Cm and $$^{246}$$Cm measured with an array of large germanium detectors in the ANNRI at J-PARC/MLF

Kimura, Atsushi; Fujii, Toshiyuki*; Fukutani, Satoshi*; Furutaka, Kazuyoshi; Goko, Shinji*; Hara, Kaoru; Harada, Hideo; Hirose, Kentaro; Hori, Junichi*; Igashira, Masayuki*; et al.

Journal of Nuclear Science and Technology, 49(7-8), p.708 - 724, 2012/07

 Times Cited Count:37 Percentile:3.43(Nuclear Science & Technology)

Journal Articles

Measurements of neutron capture cross sections at J-PARC/MLF/ANNRI, 2

Hori, Junichi*; Fujii, Toshiyuki*; Fukutani, Satoshi*; Furusaka, Michihiro*; Furutaka, Kazuyoshi; Goko, Shinji*; Harada, Hideo; Hiraga, Fujio*; Igashira, Masayuki*; Kamiyama, Takashi*; et al.

JAEA-Conf 2011-002, p.29 - 34, 2011/09

The neutron capture cross sections of $$^{93}$$Zr, $$^{99}$$Tc and $$^{107}$$Pd have been measured relative to the $$^{10}$$B(n,$$alphagamma$$) standard cross section by the neutron time-of-flight (TOF) method. Neutron capture $$gamma$$ rays were measured with a 4$$pi$$ Ge spectrometer as a part of the Accurate Neutron-Nucleus Reaction measurement Instrument (ANNRI) installed at the neutron Beam Line No.4 (BL04) of the Material and Life science experimental Facility (MLF) in the Japan Proton Accelerator Research Complex (J-PARC). This paper presents the preliminary results.

Journal Articles

Measurement of neutron-capture cross sections of palladium isotopes at the J-PARC/MLF/ANNRI

Nakamura, Shoji; Furutaka, Kazuyoshi; Goko, Shinji; Harada, Hideo; Kimura, Atsushi; Kin, Tadahiro; Kitatani, Fumito; Koizumi, Mitsuo; Ota, Masayuki; Oshima, Masumi; et al.

Journal of the Korean Physical Society, 59(2), p.1773 - 1776, 2011/08

 Times Cited Count:5 Percentile:57.14(Physics, Multidisciplinary)

A series of neutron-capture cross-section measurements using the time-of flight method has been started at the J-PARC/MLF/ANNRI. As a part of the measurements, we have measured the neutron-capture cross-sections of Pd isotopes such as $$^{105,106,108}$$Pd.

Journal Articles

Study of neutron capture reactions using the 4$$pi$$ Ge spectrometer

Harada, Hideo; Goko, Shinji*; Kimura, Atsushi; Ota, Masayuki*; Oshima, Masumi; Kitatani, Fumito; Toh, Yosuke; Furutaka, Kazuyoshi; Kin, Tadahiro; Koizumi, Mitsuo; et al.

Journal of the Korean Physical Society, 59(2), p.1547 - 1552, 2011/08

 Times Cited Count:7 Percentile:48.39(Physics, Multidisciplinary)

For the improvement of the accuracy on the neutron capture cross sections, a 4$$pi$$ Ge spectrometer was developed. The 4$$pi$$ Ge spectrometer is a unique tool due to its superior energy resolution for studying properties on neutron capture reactions, not only capture cross sections but also resonance identification, $$gamma$$-ray intensity distribution, and spin-parity assignment. For example, its performance on the resonance identification was demonstrated using a $$^{rm nat}$$Ag sample. On the measurement of a $$gamma$$-ray intensity distribution for each resonance, the results of $$^{238}$$U will be shown. Using the 4$$pi$$ Ge spectrometer, the measurements of neutron capture cross sections were started at the J-PARC/MLF/ANNRI. The preliminary results on the measurements of neutron capture cross sections will be discussed mainly based on measurements of neutron capture cross sections for $$^{241}$$Am, together with related techniques.

Journal Articles

Measurements of neutron-capture cross sections of $$^{244}$$Cm and $$^{246}$$Cm at J-PARC/MLF/ANNRI

Kimura, Atsushi; Furutaka, Kazuyoshi; Goko, Shinji*; Harada, Hideo; Kin, Tadahiro; Kitatani, Fumito; Koizumi, Mitsuo; Nakamura, Shoji; Ota, Masayuki*; Oshima, Masumi; et al.

Journal of the Korean Physical Society, 59(2), p.1828 - 1831, 2011/08

 Times Cited Count:2 Percentile:77.61(Physics, Multidisciplinary)

Journal Articles

The "Study on nuclear data by using a high intensity pulsed neutron source for advanced nuclear system" nuclear data project and the characteristics of the neutron beam line for the capture cross section experiments at J-PARC

Kiyanagi, Yoshiaki*; Kino, Koichi*; Furusaka, Michihiro*; Hiraga, Fujio*; Kamiyama, Takashi*; Kato, Kiyoshi*; Igashira, Masayuki*; Katabuchi, Tatsuya*; Mizumoto, Motoharu*; Oshima, Masumi; et al.

Journal of the Korean Physical Society, 59(2), p.1781 - 1784, 2011/08

 Times Cited Count:12 Percentile:35.48(Physics, Multidisciplinary)

The project of the comprehensive nuclear data research for the development of the advanced reactor systems had been executed successfully by eight organizations from 2005 to 2009. In this project, we constructed the pulsed neutron beamline that was aimed to obtain neutron capture cross-sections of long-lived fission products and minor actinides accurately. The energy spectra, spatial distributions, and pulses of the beam were studied by measurements and simulation calculations, and they were found to be consistent with those of the beamline design. In this paper, we present the overview of the project and the properties of the neutron beam provided by this beam line.

Journal Articles

Status and future perspectives of nuclear data measurements at J-PARC MLF BL04

Harada, Hideo; Oshima, Masumi; Kimura, Atsushi; Goko, Shinji*; Ota, Masayuki*; Furutaka, Kazuyoshi; Kin, Tadahiro; Kitatani, Fumito; Koizumi, Mitsuo; Nakamura, Shoji; et al.

JAEA-Conf 2010-005, p.9 - 14, 2010/12

The neutron-nucleus reaction instrument (NNRI) was installed at the J-PARC MLF BL04, which was designed for measuring neutron cross sections with a neutron time-of-flight technique. This includes two kinds of capture $$gamma$$-ray spectrometers: the 4$$pi$$ Ge spectrometer and the NaI spectrometers. The measurements of neutron capture cross sections for minor actinides and fission products have been started at the NNRI using these spectrometers since 2009. In this paper, the preliminary results and future perspectives are discussed.

Journal Articles

Measurement of neutron capture cross section ratios of $$^{244}$$Cm resonances using NNRI

Goko, Shinji*; Kimura, Atsushi; Harada, Hideo; Oshima, Masumi; Ota, Masayuki*; Furutaka, Kazuyoshi; Kin, Tadahiro; Kitatani, Fumito; Koizumi, Mitsuo; Nakamura, Shoji; et al.

Journal of Nuclear Science and Technology, 47(12), p.1097 - 1100, 2010/12

 Times Cited Count:5 Percentile:59.86(Nuclear Science & Technology)

To obtain the accurate nuclear data of minor actinides required for a nuclear transmutation system or an innovative nuclear fuel cycle system, measurement of neutron-capture cross section of $$^{244}$$Cm was performed using NNRI installed at beam line No.4 (BL04) of MLF in J-PARC. Using "4$$pi$$ Ge spectrometer" that is a component of NNRI, neutron time of flight spectra and prompt $$gamma$$ ray spectra were measured. Then neutron-capture cross section ratios of $$^{244}$$Cm resonances were derived and compared with the evaluated values of JENDL-3.3. The previous experimental data was measured using a nuclear explosion as a pulsed neutron source, and the present result is the first time in the world that such measurements have been carried out at an accelerator facility. By developing techniques for more detailed analysis and improvement of the experimental conditions, the absolute values of capture cross section are expected to be obtained.

Journal Articles

Influences of sedimentary history on the mechanical properties and microscopic structure change of Horonobe siliceous rocks

Sanada, Hiroyuki; Niunoya, Sumio*; Matsui, Hiroya; Fujii, Yoshiaki*

Journal of MMIJ, 125(10,11), p.521 - 529, 2009/11

This paper shows the results obtained from the laboratory tests and microscopic observation of Horonobe siliceous rocks. The consolidated undrained and drained triaxial compression tests showed different behaviors of strain-softening, pore pressure and dilatancy between diatomaceous and siliceous mudstones. Stress-strain behavior changed from strain-softening to ductile behavior under high confining pressure and pore pressure increased gradually even after peak strength for diatomaceous mudstone. Diatomaceous mudstone yielded under hydrostatic pressure of 10 MPa in isotropic consolidation test. This yielding was regarded as pore collapse based on the variation of hydraulic conductivity which was estimated from variation of volumetric strain in isotropic consolidation test, effective porosity and microscopic observation before and after the yielding.

Journal Articles

Applicability of initial stress measurement methods to Horonobe siliceous rocks and initial stress state around Horonobe Underground Research Laboratory

Sanada, Hiroyuki; Niunoya, Sumio*; Matsui, Hiroya; Fujii, Yoshiaki*

Journal of MMIJ, 125(10,11), p.530 - 539, 2009/10

Understanding initial stress in underground is important for construction of HLW repository. Evaluation of initial stress around Horonobe URL was carried out in order to understand initial stress condition and applicability of AE, DSCA and hydraulic fracturing (HF) methods to Neogene sedimentary rock. Initial stress values obtained from AE method is smaller than overburden pressure due to time dependency of Kaizer effect. Principal stress values by DSCA are similar to those by HF tests. Directions of maximum horizontal principal stresses are approximately in E-W and corresponded to HF results. Horizontal maximum and minimum principal stresses increase linearly in HF results. Deviatoric stress is acting at shallow depth. Initial stress condition approaches hydrostatic condition with depth. Direction of maximum horizontal principal stress was in E-W direction which was similar to tectonic movement around Horonobe URL by triangular surveying.

Journal Articles

Deformation and failure behavior of rock mass around the ventilation shaft in Horonobe URL

Sanada, Hiroyuki; Sugita, Yutaka; Fujii, Yoshiaki*

Proceedings of 3rd International Workshop and Conference on Earth Resources Technology 2009 (CD-ROM), p.149 - 158, 2009/05

EDZ is considered to be important issues in repositories since this is relevant to plug design, support design etc. As a part of the research and development on the geological isolation, JAEA has been implementing the Horonobe URL Project. Deformation and failure behavior around a shaft in URL is described in the paper. Tunnel shape are being measured by a laser displacement sensor to clarify dimension and mechanism of breakouts along the shaft wall. Displacement measurement by extensometers are being carried out to understand deformation behavior in the surrounding rock mass. Breakouts of about 50 cm deep in N-S direction are more frequently observed with excavation depth. The breakout direction was consistent with the maximum horizontal stress which was estimated to be approximately in E-W direction by hydrofracturing tests. Compressive deformation of rock mass also increased with excavation depth. Most part of the deformation occurred within 1 m from the shaft wall.

Journal Articles

Mechanical properties of siliceous rocks around Horonobe URL from triaxial compression and isotropic consolidation tests

Sanada, Hiroyuki; Matsui, Hiroya; Fujii, Yoshiaki*

Proceedings of International Symposium on Rock Mechanics "Rock Characterization, Modelling and Engineering Design Methods" (SINOROCK 2009) (CD-ROM), 5 Pages, 2009/05

This paper shows the results obtained from triaxial and isotropic consolidation test to select mechanical behavior of Horonobe siliceous rocks. The consolidated undrained and drained triaxial compression tests showed different behaviors of strain-softening, pore pressure and dilatancy between diatomaceous and siliceous mudstones. Stress-strain behavior changed from strain-softening to ductile behavior under high confining pressure and pore pressure increased gradually even after peak strength for diatomaceous mudstone. Diatomaceous mudstone yielded under hydrostatic pressure of 10 MPa in isotropic consolidation test. This yielding was regarded as pore collapse based on the variation of hydraulic conductivity which was estimated from variation of volumetric strain in isotropic consolidation test, effective porosity and microscopic observation before and after the yielding.

Journal Articles

Mechanical property of Horonobe siliceous rock

Sanada, Hiroyuki; Matsui, Hiroya; Fujii, Yoshiaki*

Dai-12-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (CD-ROM), p.703 - 708, 2008/09

This paper shows the result of rock mechanical investigations which have been carried out as a part of the investigations of Horonobe Underground Research Project. The results of the investigations are summarized as follows. Uniaxial compression and tensile strength of siliceous rock distributed in Wakkanai formation is larger than diatomaceous mudstone distributed in Koetoi formation. Stress-strain curve shows strain softening behavior from results of tri-axial compression test. Pore pressure and dilatancy behavior show different trends as compared with diatomaceous mudstone and siliceous rock.

Journal Articles

Consideration on poroelastic behavior of siliceous rock mass around an opening by stress-seepage coupled analysis

Sanada, Hiroyuki; Matsui, Hiroya; Yamamoto, Takuya*; Aoki, Tomoyuki*; Ogawa, Toyokazu*; Jo, Mayumi*; Fujii, Yoshiaki*

Heisei-19-Nendo Shigen, Sozai Gakkai Hokkaido Shibu Sokai Oyobi Shunki Koenkai Koen Yoshishu, p.9 - 10, 2007/06

Japan Atomic Energy Agency has been conducting the Horonobe Underground Reseach Laboratory Project as a part of geological isolation research and development at Horonobe-town in Hokkaido, Japan. The rocks around URL have high porosity and low permeability. Therefore, the excess pore pressure caused by URL excavation is possible to affect to the stability of surrounding rock. In this point of view, the authors carried out a stress-seepage coupled analysis to understand the process of the pore pressure change due to excavation and the influence to the stability of surrounding rock and support system. As a result, the large excess pore pressure causes a part in surrounding rock on excavation in an anisotropic initial stress condition and it dissipates with time. The pore pressure change causes the complex deformation in the surrounding rock as well. However, the phenomena are not significant influence to the stability of the surrounding rock and support system.

JAEA Reports

Development of a system to measure the in-situ mechanical conditions and to evaluate easiness of underground construction in the weak sedimentary rock

Ishijima, Yoji*; Fujii, Yoshiaki*; Kawakita, Minoru*; Nakama, Shigeo; Matsui, Hiroya

JNC-TY7400 2004-002, 91 Pages, 2003/03

JNC-TY7400-2004-002.pdf:3.33MB

The ratio of soft rock occupied in the whole rock mass in Japan is relatively high. Strata control problems occur more frequently in soft rock than in hard rock, since fracture and large deformation are easily induced in soft rock whose strength and stiffness are small in magnitude. A rational method to overcome these problems is to develop such system to measure the rock stresses as well as to evaluate the in-situ strength of the rock mass and to use these data to predict the phenomena occurred during nderground constructions and to reflect them to design of the rock mass structure. However, the technique of measurements which can be used in soft rock has not been developed to this day, due to many problems to overcome. Purpose of the present investigation is to develop a system to measure such components as the rock stress, the width of the fissured one and the creep deformation, by using a single borehole drilled in the soft rock. To confirm the validity of this system, the in-situ measurements were conducted in the soft iatomaceous mudstone in Horonobe district, Hokkaido, Japan. Various findings obtained in this investigation will be reported.

38 (Records 1-20 displayed on this page)