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Journal Articles

Cs-Te corrosion depth dependence on distribution of chromium carbide precipitation in high chromium steel

Sasaki, Koei; Fujimura, Ryota*; Tanigaki, Takanori; Matsubara, Masanori*; Fukumoto, Kenichi*; Uno, Masayoshi*

Journal of Nuclear Science and Technology, 54(2), p.139 - 146, 2017/02

AA2016-0211.pdf:2.83MB

 Times Cited Count:3 Percentile:40.62(Nuclear Science & Technology)

In an attempt to investigate Cs-Te corrosion depth dependence on distribution of chromium carbide precipitation in high chromium steel, Cs-Te corrosion out-pile tests of two 9Cr steels with different distributions of chromium carbide were carried out at 975K for 100h and their corrosion depths were compared. The corrosion is obviously more advanced in a specimen which has grain boundary carbide than in the one that does not. A considerable reason of the result is that the carbide distributed at grain boundaries promoted the corrosion reaction and the corrosion extended along the grain boundary. This is the first case in which the Cs-Te corrosion depth dependence on distribution of chromium carbide precipitation in Fe-Cr steel is clarified experimentally.

JAEA Reports

Study to improve recriticality evaluation methodology after severe accident (Joint research)

Kugo, Teruhiko; Ishikawa, Makoto; Nagaya, Yasunobu; Yokoyama, Kenji; Fukaya, Yuji; Maruyama, Hiromi*; Ishii, Yoshihiko*; Fujimura, Koji*; Kondo, Takao*; Minato, Hirokazu*; et al.

JAEA-Research 2013-046, 53 Pages, 2014/03

JAEA-Research-2013-046.pdf:4.42MB

The present report summarizes the results of a 2-year cooperative study between JAEA and Hitachi-GE in order to contribute to the settlement of the Fukushima-Daiichi Nuclear Power Plants which suffered from the severe accident on March 2011. In the present study, the possible scenarios to reach the recriticality events in Fukushima-Daiichi were investigated first. Then, the analytical methodology to evaluate the time-dependent recriticality events has been developed by modelling the reactivity insertion rate and the possible feedback according to the recriticality scenarios identified in the first step. The methodology developed here has been equipped as a transient simulation tool, PORCAS, which is operated on a multi-purpose platform for reactor analysis, MARBLE. Finally, the radiation exposure rates by the postulated recriticality events in Fukushima-Daiichi were approximately evaluated to estimate the impact to the public environment.

Journal Articles

Conceptual design study for the demonstration reactor of JSFR, 3; Safety design and evaluation

Tani, Akihiro*; Shimakawa, Yoshio*; Kubo, Shigenobu*; Fujimura, Ken; Yamano, Hidemasa

Proceedings of 19th International Conference on Nuclear Engineering (ICONE-19) (CD-ROM), 10 Pages, 2011/10

Journal Articles

Irradiation history of Itokawa regolith material deduced from noble gases in the Hayabusa samples

Nagao, Keisuke*; Okazaki, Ryuji*; Nakamura, Tomoki*; Miura, Yayoi*; Osawa, Takahito; Bajo, Kenichi*; Matsuda, Shintaro*; Ebihara, Mitsuru*; Ireland, T.*; Kitajima, Fumio*; et al.

Science, 333(6046), p.1128 - 1131, 2011/08

 Times Cited Count:104 Percentile:95.41(Multidisciplinary Sciences)

A steroid surface materials record regolith processes and a history of cosmic-ray irradiation. Noble gas isotopes in three rocky grains from Itokawa have been determined. High concentrations of solar He, Ne, and Ar, as high as those in lunar soils, are released at variable temperatures from each sample. The isotopic compositions are essentially identical to those of solar wind but distinguishable in He relative abundance. These noble gas characteristics can be explained by repeated implantation and preferential loss of solar He by removal of weathered He-rich rim on the grain surface through friction among regolith grains on Itokawa. Residence time of regolith materials on Itokawa is alculated to be shorter than 10 Myr, suggesting that regolith materials of small asteroids would escape easily to space.

Journal Articles

A Study on LMFBR steam generator design without tube failure propagation in water leak events

Futagami, Satoshi; Hayafune, Hiroki; Fujimura, Ken; Sato, Mitsuru*

Proceedings of 2009 International Congress on Advances in Nuclear Power Plants (ICAPP '09) (CD-ROM), p.9169_1 - 9169_8, 2009/05

The major target performance of the SG for commercialized FBR is not only economic performance but also property protection performance. The straight double wall tube SG is one of the SG candidates for commercialized FBR, and other SG concepts were studied in this paper. In proposing an alternative SG, alternative technological measures with a double wall tube were investigated and included reinforcing the tube against wastage and quick detection of initial tube leaks. Alternative SG concept candidates for preventing tube failure propagation and mitigation of water leak accidents were proposed through a combination of technological measures. At the end of JFY 2010, the straight double wall tube SG will be decided upon as the result of R&D activities, and alternative SGs evaluated in feasibility studies. A plan for studying feasibility with the technological issues of the alternative SG was proposed.

Journal Articles

Effects of oxygen annealing on dielectric properties of LuFeCuO$$_{4}$$

Matsuo, Yoji*; Suzuki, Muneyasu*; Noguchi, Yuji*; Yoshimura, Takeshi*; Fujimura, Norifumi*; Yoshii, Kenji; Ikeda, Naoshi*; Mori, Shigeo*

Japanese Journal of Applied Physics, 47(11), p.8464 - 8467, 2008/11

 Times Cited Count:10 Percentile:41.53(Physics, Applied)

We have investigated the physical properties of LuFeCuO$$_{4}$$, which is a derivative material of the electronic ferroelectric LuFe$$_{2}$$O$$_{4}$$. From electron diffraction measurements at room temperature, ionic ordering of Fe$$^{3+}$$ and Cu$$^{2+}$$ in the a-b plane was observed. This ordering is similar to that in LuFe$$_{2}$$O$$_{4}$$ and has an electric dipole. The observation of small domains (5-10 nm) indicates the presence of polar regions. Dielectric measurements showed that a peak of dielectric constant appeared at around 500 K, and the peak value was about 1000, indicating that LuFeCuO$$_{4}$$ is a dielectric material. We will present the experimental data on the samples prepared under high-pressure oxygen.

Journal Articles

Numerical investigation of cross flow phenomena in a tight-lattice rod bundle using advanced interface tracking method

Zhang, W.; Yoshida, Hiroyuki; Ose, Yasuo*; Onuki, Akira; Akimoto, Hajime; Hotta, Akitoshi*; Fujimura, Ken*

Journal of Power and Energy Systems (Internet), 2(2), p.456 - 466, 2008/00

Journal Articles

Study on cross flow phenomena in a tight-lattice rod bundle by statistical method

Zhang, W.; Yoshida, Hiroyuki; Ose, Yasuo*; Onuki, Akira; Akimoto, Hajime; Hotta, Akitoshi*; Fujimura, Ken*

Dai-12-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu, p.85 - 88, 2007/06

As a candidate for next generation reactor, the innovative FLexible-fuel-cycle Water Reactor (FLWR) adopts a remarkably tight triangular lattice arrangement with about 1 mm gap spacing between adjacent fuel rods. In relation to its design, this study presents a statistical evaluation of numerical simulation results of a detailed two-phase flow simulation code (named TPFIT). In order to make clear mechanisms of cross flow in such tight lattice rod bundles, the TPFIT is used to simulate cross flow between two modeled subchannels. Attention was focused on instantaneous fluctuation characteristics of differential pressure between two subchannels and gas/liquid mixing coefficients. With the calculation of correlation coefficients between the differential pressure and gas/liquid mixing coefficients, the time scales of cross flow, e.g. lag times were evaluated, and the effects of mixing section length, flow pattern and gap spacing on correlation coefficients were extensively investigated. The difference in mechanism between gas and liquid cross flows was pointed out.

Journal Articles

Numerical investigation of cross flow phenomena in a tight-lattice rod bundle using advanced interface tracking method

Zhang, W.; Yoshida, Hiroyuki; Ose, Yasuo*; Onuki, Akira; Akimoto, Hajime; Hotta, Akitoshi*; Fujimura, Ken*

Proceedings of 15th International Conference on Nuclear Engineering (ICONE-15) (CD-ROM), 8 Pages, 2007/04

The innovative Water Reactor for FLexible fuel cycle (FLWR) adopts a tight triangular lattice arrangement with about 1 mm gap between adjacent fuel rods. In view of the importance of accurate prediction of cross flow between subchannels in the evaluation of the boiling transition (BT) in the FLWR core, this study numerically simulated steam-water two-phase cross flow between two modeled subchannels of tight-lattice rod bundle for the FLWR by using a detailed two-phase flow simulation code with an advanced interface tracking method (named TPFIT), statistically evaluated the simulation results, and clarified mechanisms of cross flow for developing a model. The effects of flow pattern, inlet and outlet of mixing section, and gap spacing on cross flow, and the local and general characters of cross flow were extensively investigated.

Journal Articles

Improvement of predictive accuracy on subchannel analysis Code (NASCA) for tight-lattice rod bundle tests; Optimization of Ueda's entrainment model parameter and cross flow model parameters

Chitose, Hiromasa*; Hotta, Akitoshi*; Onuki, Akira; Fujimura, Ken*

Proceedings of 14th International Conference on Nuclear Engineering (ICONE-14) (CD-ROM), 6 Pages, 2006/07

no abstracts in English

JAEA Reports

Study on high-performance fuel cladding materials; Joint research report in FY 2001-2005 (Phase 2) (Joint research)

Kiuchi, Kiyoshi; Ioka, Ikuo; Tanabe, Makoto*; Nanjo, Yoshiyasu*; Ogawa, Hiroaki; Ishijima, Yasuhiro; Tsukatani, Ichiro; Ochiai, Takamasa; Kizaki, Minoru; Kato, Yoshiaki; et al.

JAEA-Research 2006-023, 173 Pages, 2006/03

JAEA-Research-2006-023.pdf:20.51MB

The research concerning new cladding materials for ultra-high burnup of fuel elements with MOX fuels aiming at 100 GWd/t of BWR was pursued for 5 years from 2001 to 2005. On the Phase 1, the modified stainless steel of Fe-25Cr-35Ni-0.2Ti as fuel claddings and Nb-Mo alloy as a liner for inhibiting the pellet- clad interaction were selected as candidate materials, by evaluating fundamental properties required to BWR cladding materials, that are the nuclear economy, radioactivity, mass-transfer, irradiation properties, mechanical properties so on. On the present study, the making process of cladding tubes, lining by diffusion bonding, end plug by laser welding were developed and optimized, by considering the practical use of fuel elements consists of these candidates. The practical applicability was basically examined by irradiation tests using the accelerator of TIARA and the research reactor of JRR-3, for mainly confirming the resistance to IGSCC as one of the current important issues of BWR core materials of low carbon grade stainless steels. Creep and fatigue testing data were also obtained for evaluating the long performance of candidate materials. The behavior as fuel elements was analyzed with the safety calculation code for BWRs. The obtained results were established as a data base system, by considering the applicability to the fuel design and in-pile loop tests.

Journal Articles

Microscopic structure of the Gamow-Teller resonance in $$^{58}$$Cu

Hara, Keigo*; Adachi, Takeshi*; Akimune, Hidetoshi*; Daito, Izuru*; Fujimura, Hisako*; Fujita, Yoshitaka*; Fujiwara, Mamoru; Fushimi, Kenichi*; Hara, Kaoru*; Harakeh, M. N.*; et al.

Physical Review C, 68(6), p.064612_1 - 064612_9, 2003/12

 Times Cited Count:11 Percentile:59.58(Physics, Nuclear)

no abstracts in English

Journal Articles

Beam-palarization asymmetries for the $$p$$($$overrightarrow{gamma}$$,$$K$$$$^{+}$$)$$Lambda$$ and $$p$$($$overrightarrow{gamma}$$,$$K$$$$^{+}$$)$$Sigma$$$$^{0}$$ reactions for $$E$$$$_{gamma}$$=1.5-2.4 GeV

Zegers, R. G. T.*; Sumihama, Mizuki*; Ahn, D. S.*; Ahn, J. K.*; Akimune, Hidetoshi*; Asano, Yoshihiro; Chang, W. C.*; Dat$'e$, S.*; Ejiri, Hiroyasu*; Fujimura, Hisako*; et al.

Physical Review Letters, 91(9), p.092001_1 - 092001_4, 2003/08

 Times Cited Count:127 Percentile:95.25(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Evidence for a narrow $$S$$ = +1 Baryon resonance in photoproduction from the neutron

Nakano, Takashi*; Ahn, D. S.*; Ahn, J. K.*; Akimune, Hidetoshi*; Asano, Yoshihiro; Chang, W. C.*; Date, S.*; Ejiri, Hiroyasu*; Fujimura, Hisako*; Fujiwara, Mamoru; et al.

Physical Review Letters, 91(1), p.012002_1 - 012002_4, 2003/07

 Times Cited Count:994 Percentile:99.88(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Dipole excitation of $$alpha$$ clusters in $$^{6}$$Li and $$^{7}$$Li

Nakayama, Shintaro*; Yamagata, Tamio*; Akimune, Hidetoshi*; Daito, Izuru*; Fujimura, Hisako*; Fujita, Yoshitaka*; Fujiwara, Mamoru; Fushimi, Kenichi*; Greenfield, M. B.*; Kori, Hideki*; et al.

Physical Review Letters, 87(12), p.122502_1 - 122502_4, 2001/09

 Times Cited Count:20 Percentile:70(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Soft dipole resonance in the neutron-skin nucleus $$^{6}$$He

Nakayama, Shintaro*; Yamagata, Tamio*; Akimune, Hidetoshi*; Daito, Izuru*; Fujimura, Hisako*; Fujita, Yoshitaka*; Fujiwara, Mamoru; Fushimi, Kenichi*; Inomata, Toru*; Kori, Hideki*; et al.

Physical Review Letters, 85(2), p.262 - 265, 2000/07

 Times Cited Count:72 Percentile:89.44(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Ferrocene-containing polymers, 1; Radiation-induced polymerization of ferrocenylmethyl methacrylate

*; *; ; Yoshida, Kenzo; Fujimura, Takashi;

Journal of Polymer Science; Polymer Chemistry Edition, 17(1), p.173 - 184, 1979/00

no abstracts in English

JAEA Reports

2nd power-up test for JRR-2

Kambara, Toyozo; Uno, Hidero; Shoda, Katsuhiko; Hirata, Yutaka; Shoji, Tsutomu; Kohayakawa, Toru; Takayanagi, Hiroshi; Fujimura, Tsutomu; Morita, Morito; Ichihara, Masahiro; et al.

JAERI 1045, 11 Pages, 1963/03

JAERI-1045.pdf:0.72MB

no abstracts in English

Oral presentation

Study on gas-liquid two-phase flow characteristics in a tight-lattice bundle, 1; Master plan and experiments

Onuki, Akira; Tamai, Hidesada; Yoshida, Hiroyuki; Shibata, Mitsuhiko; Akimoto, Hajime; Chitose, Hiromasa*; Hotta, Akitoshi*; Fujimura, Ken*

no journal, , 

no abstracts in English

Oral presentation

Post irradiation evaluation of high purity stainless steel for high-performance fuel cladding

Ioka, Ikuo; Ishijima, Yasuhiro; Kiuchi, Kiyoshi; Kizaki, Minoru; Kato, Yoshiaki; Fujimura, Ken*; Obata, Hiroyuki*

no journal, , 

The IASCC and loss of ductility concerning new cladding materials for ultra-high burnup of fuel elements with MOX fuels aiming at 100GWd/t of BWR was performed after neutron irradiation. The specimens machined from tubes made of Fe-25Cr-35Ni-0.2Ti UHP and SUS304 were irradiated at 290$$^{circ}$$C up to 1.8dpa(1.5$$times$$10$$^{25}$$n/m$$^{2}$$) in JRR-3. The ultimate tensile strength of both specimens increased and the fracture elongation decreased in tensile test at 288$$^{circ}$$C. The loss of ductility was almost equal with data of previous literatures. IASCC was recognized on SUS304 by SSRT testing under high temperature water, but not on Fe-25Cr-35Ni-0.2Ti UHP.

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