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Journal Articles

Quasielastic neutron scattering probing H$$^{-}$$ dynamics in the H$$^{-}$$ conductors LaH$$_{3-2x}$$O$$_{x}$$

Tamatsukuri, Hiromu; Fukui, Keiga*; Iimura, Soshi*; Honda, Takashi*; Tada, Tomofumi*; Murakami, Yoichi*; Yamaura, Junichi*; Kuramoto, Yoshio*; Sagayama, Hajime*; Yamada, Takeshi*; et al.

Physical Review B, 107(18), p.184114_1 - 184114_8, 2023/05

 Times Cited Count:0 Percentile:0(Materials Science, Multidisciplinary)

JAEA Reports

Degradation behavior of optical components by gamma irradiation (Contract research)

Takeuchi, Tomoaki; Shibata, Hiroshi; Hanakawa, Hiroki; Uehara, Toshiaki*; Ueno, Shunji*; Tsuchiya, Kunihiko; Kumahara, Hajime*; Shibagaki, Taro*; Komanome, Hirohisa*

JAEA-Technology 2017-026, 26 Pages, 2018/02

JAEA-Technology-2017-026.pdf:4.0MB

Under severe accidents, high-integrity transmission techniques are necessary so as to monitor the situation of the nuclear power plant. In this study, effects of gamma irradiation up to 10$$^{6}$$Gy on properties of optical devices were evaluated toward the development of a radiation-resistant in-water wireless transmission system using visible light. After the irradiation, for the LEDs, the total luminous flux decreased and the browning of resin lenses occurred. Meanwhile, the current-voltage characteristics hardly changed. For the PDs, the light sensitivity decreased and the browning of resin window occurred. The dark currents of PDs did not become large enough to adversely affect transmission. These results indicated that both the decreases of the total luminous flux of the LEDs and the light sensitivity of the PDs were mainly caused by not the degradation of the semiconductor parts but the browning of the resin parts by the irradiation. In addition, basic decrease behaviors of light transmission of several different types of glasses by gamma irradiation were also obtained so as to select the suitable optical windows and filters for the developing radiation-resistant in-water wireless transmission system.

Journal Articles

Degradation behavior of LED by $$gamma$$ irradiation

Takeuchi, Tomoaki; Shibata, Hiroshi; Otsuka, Noriaki; Uehara, Toshiaki; Kumahara, Hajime*; Tsuchiya, Kunihiko

JAEA-Review 2015-022, JAEA Takasaki Annual Report 2014, P. 29, 2016/02

$$gamma$$ irradiation effects on LEDs which were fabricated by different two fabricators and had relatively large amount of light were evaluated toward the development of a radiation-resistant in-water wireless transmission system using visible light. The current-voltage characteristics and total luminous flux of the LEDs were measured before and after the irradiation. After the irradiation, the total luminous flux decreased and the resin lenses turned oxblood. Meanwhile, the current-voltage characteristics hardly changed. These results indicated that the decreases of the total luminous flux of the LEDs were mainly caused by not the degradation of the semiconductor parts but the coloring of the resin parts by the irradiation. On the other hand, the decrease rates of the total lumious fluxes with $$gamma$$ absorbed dose of the LEDs fabricated one fabricator were smaller than the others. Therefore, they are possible candidates for the light emitting devices of the developing in-water transmission system.

Journal Articles

Degradation behavior of LED and photo diode by $$gamma$$ irradiation

Takeuchi, Tomoaki; Hanakawa, Hiroki; Shibata, Hiroshi; Uehara, Toshiaki; Ueno, Shunji; Kumahara, Hajime*; Tsuchiya, Kunihiko

JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 33, 2015/03

$$gamma$$ irradiation effects on LEDs and photo diodes (PDs) were evaluated toward the development of a radiation-resistant in-water wireless transmission system using visible light. The current-voltage characteristics and total luminous flux of the LEDs and the dark current and light sensitivity of the PDs were measured before and after the irradiation. After the irradiation, for the LEDs, the total luminous flux decreased and the resin lenses turned oxblood. Meanwhile, the current-voltage characteristics hardly changed. For the PDs, the light sensitivity decreased and the resin window turned oxblood while the dark currents stayed at most 10 nA. These results indicated that both the decreases of the total luminous flux of the LEDs and the light sensitivity of the PDs were mainly caused by not the degradation of the semiconductor parts but the coloring of the resin parts by the irradiation.

Journal Articles

Spatial distribution of $$Delta$$$$^{14}$$C values of organic matter in surface sediments off Saru River in northern Japan, one year after a flood event in 2006

Nagao, Seiya*; Irino, Tomohisa*; Aramaki, Takafumi*; Ikehara, Ken*; Katayama, Hajime*; Otosaka, Shigeyoshi; Uchida, Masao*; Shibata, Yasuyuki*

Radiocarbon, 52(3), p.1068 - 1077, 2010/08

 Times Cited Count:0 Percentile:0.01(Geochemistry & Geophysics)

This study discusses the effects of flooding on the spatial distribution of organic matter on the shelf region of off the Saru River, southern part of Hokkaido, Japan, on the basis of the $$Delta$$$$^{14}$$C and $$delta$$$$^{13}$$C values. Surface sediments on the shelf were collected in August 2007, one year after the severe flood in 2006. Suspended particles and sediment of the Saru River were also collected in August 2007 and 2008. The $$Delta$$$$^{14}$$C values of organic matter in the shelf sediments ranged from -665 to -77 per mil. The silt and clay sediments had $$Delta$$$$^{14}$$C values of -240 to -77 per mil, but the sandy sediments ranged from -665 to -388 per mil. The $$Delta$$ values of particulate organic carbon in the Saru River are -292 to -247 per mil at normal flow conditions. These results indicate that surface soil with relatively older organic matter is deposited on the shelf region by the flooding event, and freshly-produced organic matter in sea surface is deposited after the flooding.

Journal Articles

C-axis critical current of a PrFeAsO$$_{0.7}$$ single crystal

Kashiwaya, Hiromi*; Shirai, Kazumi*; Matsumoto, Tetsuro*; Shibata, Hajime*; Kambara, Hiroshi*; Ishikado, Motoyuki; Eisaki, Hiroshi*; Iyo, Akira*; Shamoto, Shinichi; Kurosawa, Itaru*; et al.

Applied Physics Letters, 96(20), p.202504_1 - 202504_3, 2010/05

 Times Cited Count:28 Percentile:71.55(Physics, Applied)

The ${it c}$-axis transport properties of a high-pressure synthesized PrFeAsO$$_{0.7}$$ single crystal are studied using s-shaped junctions. Resistivity anisotropy of about 120 detected at 50 K shows the presence of strong anisotropy in the electronic states. The obtained critical current density for the ${it c}$-axis of 2.9 $$times$$ 10$$^{5}$$ A/cm$$^{2}$$ is two orders of magnitude larger than that in Bi$$_{2}$$Sr$$_{1.6}$$La$$_{0.4}$$CuO$$_{6+delta}$$. The appearance of a hysteresis in the current-voltage curve below ${it T}$ $$_{c}$$ is the manifestation of the intrinsic Josephson effect similar to that in cuprate superconductors. The suppression of the critical current-normal resistance (${it I}$ $$_{c}$$ ${it R}$ $$_{n}$$) product is explained by an inspecular transport in ${it s}$ $$_{pm}$$ -wave pair potential.

Journal Articles

Development of design technology on thermal-hydraulic performance in tight-lattice rod bundles, 6; Estimation of void fraction

Kureta, Masatoshi; Tamai, Hidesada; Sato, Takashi; Shibata, Mitsuhiko; Onuki, Akira; Akimoto, Hajime

Proceedings of 15th International Conference on Nuclear Engineering (ICONE-15) (CD-ROM), 11 Pages, 2007/04

Five types of void fraction experiments with 7-, 14-, 19- and 37-rod and rod-gap of 1.0-1.3 mm bundle and spacer effect tests are being conducted under from the atmospheric pressure to 7.2 MPa, and also applicability of the numerical analysis codes and drift-flux model to the tight-lattice rod bundle on void fraction estimation were evaluated based on the comparison of these void fraction calculation methods with the experimental data. Because the tendency of the calculated void fraction by these codes and measured data was similar within the measurement error, for evaluation on void fraction distribution, these codes can apply to the tight-lattice rod bundles.

JAEA Reports

Report of Examination of the Sample from Core Shroud (2F2-H3) at Fukushima Dai-ni Power Station Unit-2 (Contract research)

The Working Team for Examination of the Sample from Core Shrouds and Primary Loop Recirculation Pipi; Nakajima, Hajime*; Shibata, Katsuyuki; Tsukada, Takashi; Suzuki, Masahide; Kiuchi, Kiyoshi; Kaji, Yoshiyuki; Kikuchi, Masahiko; Ueno, Fumiyoshi; Nakano, Junichi; et al.

JAERI-Tech 2004-015, 114 Pages, 2004/03

JAERI-Tech-2004-015.pdf:38.06MB

The Tokyo Electric Power Company (TEPCO) visually inspected the weld joint of core shroud at Fukushima Dai-ni Nuclear Power Station Unit-2 by a direction of the Nuclear and Industrial Agency, cracks were observed at outer side of the ring weld joint (H3) between a core shroud middle trunk and a middle ring. TEPCO has conducted a material examination with Nippon Nuclear Fuel Development Co. Ltd. (NFD) on the specimen including cracks sampled from the core shroud. The present examination has been performed with the objective to independently investigate and evaluate the materials by jointly attending the examination with NFD from the planning stage. Based on results of the present examination, the probable presence of tensile residual stress by welding process and dissolved oxygen contents in the cooling water, it was shown that the cracks were considered to be stress corrosion cracking (SCC). However, the cause of the cracks needs more consideration on the way of shroud construction.

Journal Articles

High performance tokamak experiments with a ferritic steel wall on JFT-2M

Tsuzuki, Kazuhiro; Kimura, Haruyuki; Kawashima, Hisato; Sato, Masayasu; Kamiya, Kensaku; Shinohara, Koji; Ogawa, Hiroaki; Hoshino, Katsumichi; Bakhtiari, M.; Kasai, Satoshi; et al.

Nuclear Fusion, 43(10), p.1288 - 1293, 2003/10

 Times Cited Count:39 Percentile:74.34(Physics, Fluids & Plasmas)

no abstracts in English

JAEA Reports

Study on structural integrity evaluation of core shroud based on crack growth analysis (Contract research)

Onizawa, Kunio; Tsutsumi, Hideaki*; Suzuki, Masahide; Shibata, Katsuyuki; Ueno, Fumiyoshi; Kaji, Yoshiyuki; Tsukada, Takashi; Nakajima, Hajime*

JAERI-Tech 2003-073, 125 Pages, 2003/08

JAERI-Tech-2003-073.pdf:11.62MB

Concerning the cracks due to stress corrosion cracking (SCC) observed on the core shrouds of BWRs, a study was conducted on structural integrity evaluation based on crack growth analysis. The cracks investigated were those observed on the regions of lower ring and support ring of the core shroud at Kashiwazaki-Kariwa Nuclear Power Station (NPS) Unit-3, and that on the middle shell region of the core shroud at Fukushima Daiichi NPS Unit-4 of Tokyo Electric Power Company. It was confirmed through data analysis of past SCC growth rate experiments applicable to the condition of the ring regions that the SCC growth rate prescribed in the JSME rule was conservative. The analysis on the core shroud rigidity with a crack indicated that the rigidity reduction was small enough not to affect the dynamic seismic response for the regions studied. Through the comparison of the required area in a cracked section or the allowable crack length, and crack growth analysis results, it was confirmed that the integrity of the core shrouds would be maintained even 4 effective full power years later.

Journal Articles

Study on gas-liquid two-phase flow distribution in a tight-lattice rod bundle

Onuki, Akira; Shibata, Mitsuhiko; Tamai, Hidesada; Akimoto, Hajime; Yamauchi, Toyoaki*; Mizokami, Shinya*

Nihon Konsoryu Gakkai Nenkai Koenkai 2003 Koen Rombunshu, p.35 - 36, 2003/07

Analytical evaluation of maximum critical power by so-called subchannnel code is indispensable for design of reduced moderation water reactor. In this study, two-phase flow distribution in a tight-lattice rod bundle is investigated using 19-rod bundle experimental rig and subchannnel analysis code NASCA. The flow distribution was measured under so-called churn flow regime and the predictive capability of NASCA was assessed. NASCA can predict the flow distribution qualitatively depending on local pressure drop. Quantitative prediction is also reasonable for liquid phase but the gas phase distribution was underestimated. Void-drift model has a dominant contribution and we should improve the model for the tight-lattice rod bundle.

Journal Articles

Experimental results of functional performance of a vacuum vessel pressure suppression system in ITER

Shibata, Mitsuhiko; Takase, Kazuyuki; Watanabe, Hironori; Akimoto, Hajime

Fusion Engineering and Design, 63-64, p.217 - 222, 2002/12

 Times Cited Count:5 Percentile:34.65(Nuclear Science & Technology)

no abstracts in English

JAEA Reports

Study on operation conditions and an operation system of a nuclear powered submersible research vessel; Report of working group on application of a very small nuclear reactor to an ocean research

Ura, Tamaki*; Takamasa, Tomoji*; Nishimura, Hajime*; Aoki, Taro*; Ueno, Michio*; Maeda, Toshio*; Nakamura, Masato*; Shimazu, Shunsuke*; Tokunaga, Sango*; Shibata, Yozo*; et al.

JAERI-Tech 2001-049, 154 Pages, 2001/07

JAERI-Tech-2001-049.pdf:11.24MB

JAERI has studied on design and operation of a nuclear powered submersible research vessel, which will navigate under sea in the Arctic Ocean, as a part of the design study of advanced marine reactors. This report describes operation conditions and an operating system of the vessel those were discussed by the specialists of hull design, sound positioning, ship motions and oceanography, etc. The design conditions on ship motions for submersible vessels were surveyed considering regulations in our country, and ship motions were evaluated assuming the observation activities in the Arctic Ocean. A submarine transponder system and an on ice communication buoy system were examined as a positioning and communication system supposing the activity under ice. Procedures to secure safety of nuclear powered submersible research vessel were discussed based on the investigation of accidents. These results were reflected to the concept of the nuclear powered submersible research vessel, and subjects fto be settled in the next step were clarified.

Journal Articles

Boiling and condensation of water discharged into a vacuum vessel of a fusion reactor

Takase, Kazuyuki; Ose, Yasuo*; Shibata, Mitsuhiko; Akimoto, Hajime

Dai-38-Kai Nihon Dennetsu Shimpojiumu Koen Rombunshu, p.641 - 642, 2001/00

no abstracts in English

Journal Articles

Ion collection from photoionized plasma with a wire electrode in weak magnetic field

Adachi, Hajime; Tamura, Koji; Ogura, Koichi; Shibata, Takemasa

Japanese Journal of Applied Physics, 38(12A), p.6887 - 6889, 1999/12

 Times Cited Count:2 Percentile:18.88(Physics, Applied)

no abstracts in English

Journal Articles

Charge transfer cross sections for uranium

Tamura, Koji; Adachi, Hajime*; Ogura, Koichi; Oba, Hironori; Shibata, Takemasa

Japanese Journal of Applied Physics, Part 1, 38(11), p.6512 - 6516, 1999/11

 Times Cited Count:12 Percentile:50.97(Physics, Applied)

no abstracts in English

Journal Articles

Charge transfer cross sections for dysprosium and cerium

Tamura, Koji; Adachi, Hajime; Shibata, Takemasa

Japanese Journal of Applied Physics, Part 1, 38(5A), p.2973 - 2977, 1999/05

 Times Cited Count:6 Percentile:32.57(Physics, Applied)

no abstracts in English

Journal Articles

Secondary electron emission yield from uranium surface due to uranium ion bombardment

Tamura, Koji; ; Adachi, Hajime; Oba, Hironori; Shibata, Takemasa

Japanese Journal of Applied Physics, Part 1, 38(4A), p.2122 - 2123, 1999/04

 Times Cited Count:8 Percentile:43.01(Physics, Applied)

no abstracts in English

JAEA Reports

Charge transfer cross section for uranium

Adachi, Hajime; Tamura, Koji; ; Ogura, Koichi; Oba, Hironori; Shibata, Takemasa

JAERI-Research 99-029, 19 Pages, 1999/03

JAERI-Research-99-029.pdf:0.94MB

no abstracts in English

JAEA Reports

Secondary electron emission from uranium surface due to uranium ion bombardment

Tamura, Koji; ; Adachi, Hajime; Oba, Hironori; Shibata, Takemasa

JAERI-Research 98-073, 10 Pages, 1998/12

JAERI-Research-98-073.pdf:0.52MB

no abstracts in English

35 (Records 1-20 displayed on this page)