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Journal Articles

Simultaneous sequestration of Co$$^{2+}$$ and Mn$$^{2+}$$ by fungal manganese oxide through asbolane formation

Aoshima, Miku*; Tani, Yukinori*; Fujita, Rina*; Tanaka, Kazuya; Miyata, Naoyuki*; Umezawa, Kazuhiro*

Minerals (Internet), 12(3), p.358_1 - 358_16, 2022/03

 Times Cited Count:4 Percentile:85.88(Geochemistry & Geophysics)

In this study, we conducted sequestration experiments of Co$$^{2+}$$ by ${it Acremonium strictum}$ KR21-2 in a Mn$$^{2+}$$/Co$$^{2+}$$ binary solution at pH7. The sequestration of Co$$^{2+}$$ by newly formed BMOs readily progressed in parallel with the exogenous Mn$$^{2+}$$, with higher efficiency than that in single Co$$^{2+}$$ solutions. This is attributed to a synergetic effect on Co$$^{2+}$$ sequestration through the formation of asbolane in Mn$$^{2+}$$/Co$$^{2+}$$ binary systems.

Journal Articles

Design for detecting recycling muon after muon-catalyzed fusion reaction in solid hydrogen isotope target

Okutsu, Kenichi*; Yamashita, Takuma*; Kino, Yasushi*; Nakashima, Ryota*; Miyashita, Konan*; Yasuda, Kazuhiro*; Okada, Shinji*; Sato, Motoyasu*; Oka, Toshitaka; Kawamura, Naritoshi*; et al.

Fusion Engineering and Design, 170, p.112712_1 - 112712_4, 2021/09

 Times Cited Count:2 Percentile:25.87(Nuclear Science & Technology)

A muonic molecule which consists of two hydrogen isotope nuclei (deuteron (d) or tritium (t)) and a muon decays immediately via nuclear fusion and the muon will be released as a recycling muon, and start to find another hydrogen isotope nucleus. The reaction cycle continues until the muon ends up its lifetime of 2.2 $$mu$$s. Since the muon does not participate in the nuclear reaction, the reaction is so called a muon catalyzed fusion ($$mu$$CF). The recycling muon has a particular kinetic energy (KE) of the muon molecular orbital when the nuclear reaction occurs. Since the KE is based on the unified atom limit where distance between two nuclei is zero. A precise few-body calculation estimating KE distribution (KED) is also in progress, which could be compared with the experimental results. In the present work, we observed recycling muons after $$mu$$CF reaction.

Journal Articles

Time evolution calculation of muon catalysed fusion; Emission of recycling muons from a two-layer hydrogen film

Yamashita, Takuma*; Okutsu, Kenichi*; Kino, Yasushi*; Nakashima, Ryota*; Miyashita, Konan*; Yasuda, Kazuhiro*; Okada, Shinji*; Sato, Motoyasu*; Oka, Toshitaka; Kawamura, Naritoshi*; et al.

Fusion Engineering and Design, 169, p.112580_1 - 112580_5, 2021/08

 Times Cited Count:3 Percentile:46.88(Nuclear Science & Technology)

A muon ($$mu$$) having 207 times larger mass of electron and the same charge as the electron has been known to catalyze a nuclear fusion between deuteron (d) and triton (t). These two nuclei are bound by $$mu$$ and form a muonic hydrogen molecular ion, dt$$mu$$. Due to the short inter-nuclear distance of dt$$mu$$, the nuclear fusion, d +t$$rightarrow alpha$$ + n + 17.6 MeV, occurs inside the molecule. This reaction is called muon catalyzed fusion ($$mu$$CF). Recently, the interest on $$mu$$CF is renewed from the viewpoint of applications, such as a source of high-resolution muon beam and mono-energetic neutron beam. In this work, we report a time evolution calculation of $$mu$$CF in a two-layered hydrogen isotope target.

Journal Articles

Influence of temperature histories during reactor startup periods on microstructural evolution and mechanical properties of austenitic stainless steel irradiated with neutrons

Kasahara, Shigeki; Kitsunai, Yuji*; Chimi, Yasuhiro; Chatani, Kazuhiro*; Koshiishi, Masato*; Nishiyama, Yutaka

Journal of Nuclear Materials, 480, p.386 - 392, 2016/11

 Times Cited Count:0 Percentile:0.01(Materials Science, Multidisciplinary)

This paper addresses influence of two different temperature profiles during startup periods in the Japan Materials Testing Reactor and a boiling water reactor upon microstructural evolution and mechanical properties of austenitic stainless steel irradiated with neutrons to about 1 dpa and 3 dpa. Tensile tests at 290$$^{circ}$$C and Vickers hardness tests at room temperature were carried out, and their microstructures were observed by FEG-TEM. Influence of difference in the temperature profiles was observed obviously in interstitial cluster formation, in particular, growth of Frank loops. The influence was also found certainly in loss of strain hardening capacity and ductility, although the influence on the yield strength and the Vickers hardness was not clearly observed. As a result, Frank loops, which were observed in austenitic stainless steel irradiated at doses of 1 dpa or more, were considered to contribute to deformation of the austenitic stainless steel.

Journal Articles

Correlation between locally deformed structure and oxide film properties in austenitic stainless steel irradiated with neutrons

Chimi, Yasuhiro; Kitsunai, Yuji*; Kasahara, Shigeki; Chatani, Kazuhiro*; Koshiishi, Masato*; Nishiyama, Yutaka

Journal of Nuclear Materials, 475, p.71 - 80, 2016/07

 Times Cited Count:8 Percentile:63.78(Materials Science, Multidisciplinary)

To elucidate the mechanism of irradiation-assisted stress corrosion cracking (IASCC) in high-temperature water for neutron-irradiated austenitic stainless steels (SSs), the locally deformed structures, the oxide films formed on the deformed areas, and their correlation were investigated. Tensile specimens made of irradiated 316L SSs were strained 0.1%-2% at room temperature or at 563 K, and the surface structures and crystal misorientation among grains were evaluated. The strained specimens were immersed in high-temperature water, and the microstructures of the oxide films on the locally deformed areas were observed. The appearance of visible step structures on the specimens' surface depended on the neutron dose and the applied strain. The surface oxides were observed to be prone to increase in thickness around grain boundaries (GBs) with increasing neutron dose and increasing local strain at the GBs. No penetrative oxidation was observed along GBs or along surface steps.

Journal Articles

Recent progress in the chopper spectrometer 4SEASONS at J-PARC

Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Kamazawa, Kazuya*; Ikeuchi, Kazuhiko*; Iida, Kazuki*; Ishikado, Motoyuki*; Nakajima, Kenji; Kawamura, Seiko; Nakatani, Takeshi; et al.

JAEA-Conf 2015-002, p.319 - 329, 2016/02

Journal Articles

Thermal engineering of non-local resistance in lateral spin valves

Kasai, Shinya*; Hirayama, Yusuke*; Takahashi, Yukiko*; Mitani, Seiji*; Hono, Kazuhiro*; Adachi, Hiroto; Ieda, Junichi; Maekawa, Sadamichi

Applied Physics Letters, 104(16), p.162410_1 - 162410_4, 2014/04

 Times Cited Count:14 Percentile:54.07(Physics, Applied)

Journal Articles

Investigation on iodine release behavior during the operation of high temperature engineering test reactor (HTTR)

Ueta, Shohei; Inoi, Hiroyuki; Mizutani, Yoshitaka; Ohashi, Hirofumi; Iwatsuki, Jin; Sakaba, Nariaki; Sawa, Kazuhiro

Proceedings of 21st International Conference on Nuclear Engineering (ICONE-21) (DVD-ROM), 4 Pages, 2013/07

Japan Atomic Energy Agency (JAEA) has planned to investigate on iodine release behavior from fuel through the testing operation of High Temperature Engineering Test Reactor (HTTR) in order to contribute to the reasonable estimation of the radiation exposure necessary for the realization of HTGR in the future. In this test, the fractional release of iodine will be measured and evaluated by measuring xenon isotopes, the daughter nuclides of iodine isotopes, in the primary coolant sampling under the loss-of-forced cooling (LOFC) test by which the primary coolant circulator is shut down and/or the manual scram test of HTTR. In parallel, the local area of primary coolant circuit where iodine is plated-out will be evaluated. This paper describes the testing plan and the preliminary analytical study on the release behavior of iodine and xenon isotopes through the operation of HTTR.

Journal Articles

Evaluation techniques of the materials for nuclear power plants

Kasahara, Shigeki; Chatani, Kazuhiro*

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 54(3), p.205 - 209, 2012/03

The serial lecture of "Materials for Nuclear Energy Systems; Towards High Reliability" introduced technical trends and topics, which focused on the materials development and application for nuclear energy systems. In this article which is titled "Evaluation Techniques of the Materials for Nuclear Power Plants", some examples of the evaluation methods for the integrity of the components, pipings, reactor vessels and their internals are explained from the viewpoints of material evaluation for nuclear power plants. In addition, progress of technical development is introduced on the fracture toughness examinations for the materials irradiated with neutrons of reactor vessel internals.

Journal Articles

IASCC evaluation method for irradiated core internal structures in BWR power plants

Takakura, Kenichi*; Tanaka, Shigeaki*; Nakamura, Tomomi*; Chatani, Kazuhiro*; Kaji, Yoshiyuki

Proceedings of 2010 ASME Pressure Vessels and Piping Conference (PVP 2010) (CD-ROM), 10 Pages, 2010/07

Irradiation Assisted Stress Corrosion Cracking (IASCC) is a matter of great concern as a degradation of core internal components in light water nuclear reactor. Japan Nuclear Energy Safety organization (JNES) had been conducting a project related to IASCC as a part of safety research and development study for the aging management and maintenance of the nuclear power plants. Based on the JNES project results, JNES proposed "IASCC evaluation guide for BWR core internals". The purpose of this paper is to describe the background of the guide, especially crack growth rate (CGR) tests for irradiated stainless steels.

Journal Articles

Measurement and analysis of reactivity worth of $$^{237}$$Np sample in cores of TCA and FCA

Sakurai, Takeshi; Mori, Takamasa; Okajima, Shigeaki; Tani, Kazuhiro*; Suzaki, Takenori*; Saito, Masaki*

Journal of Nuclear Science and Technology, 46(6), p.624 - 640, 2009/06

 Times Cited Count:5 Percentile:36.83(Nuclear Science & Technology)

Journal Articles

Development of optical fiber detector for measurement of fast neutron

Yagi, Takahiro*; Misawa, Tsuyoshi*; Pyeon, C. H.*; Unesaki, Hironobu*; Shiroya, Seiji*; Kawaguchi, Shinichi*; Okajima, Shigeaki; Tani, Kazuhiro*

Proceedings of International Conference on the Physics of Reactors, Nuclear Power; A Sustainable Resource (PHYSOR 2008) (CD-ROM), 8 Pages, 2008/09

In order to insert a neutron detector in a narrow space such as a gap of between fuel plates and measure the fast neutrons in real time, a neutron detector with an optical fiber has been developed. This detector consists of an optical fiber whose tip is covered with mixture of neutron converter material and scintillator such as ZnS(Ag). The detector for fast neutrons uses ThO$$_{2}$$ as converter material because $$^{232}$$Th makes fission reaction with fast neutrons. The place where $$^{232}$$Th can be uses is limited by regulations because $$^{232}$$Th is nuclear fuel material. The purpose of this research is to develop a new optical fiber detector to measure fast neutrons without $$^{232}$$Th and to investigate the characteristic of the detector. These detectors were used to measure a D-T neutron generator and fast neutron flux distribution at Fast Critical Assembly. The results showed that the fast neutron flux distribution of the new optical fiber detector with ZnS(Ag) was the same as it of the activation method, and the detector are effective for measurement of fast neutrons.

Journal Articles

Numerical analysis of the hydrogen atom density in a negative ion source

Takato, Naoyuki; Hanatani, Junji*; Mizuno, Takatoshi*; Hatayama, Akiyoshi*; Tobari, Hiroyuki; Hanada, Masaya; Inoue, Takashi; Taniguchi, Masaki; Dairaku, Masayuki; Kashiwagi, Mieko; et al.

AIP Conference Proceedings 925, p.38 - 45, 2007/09

The production and transport processes of the H$$^0$$ atom are numerically simulated to obtain the H$$^0$$ atom density. The three dimensional transport code using the Monte Carlo method has been applied to H$$^0$$ atoms in the large "JAEA 10 ampere negative ion source" under the Cs-seeded condition. In this study, the production rate of H$$^0$$ atoms through the dissociation process of H$$_2$$ molecules is estimated from single probe characteristics of the Langmuir probe measurement. In addition, the energy relaxation process of H$$^0$$ atoms is also considered. The results show that the existence of high-energy electrons and the energy relaxation process of H$$^0$$ atoms affect the H$$^0$$ atom density.

Journal Articles

IASCC crack growth rate of neutron irradiated low carbon austenitic stainless steels in simulated BWR condition

Chatani, Kazuhiro*; Takakura, Kenichi*; Ando, Masami*; Nakata, Kiyotomo*; Tanaka, Shigeaki*; Ishiyama, Yoshihide*; Hishida, Mamoru*; Kaji, Yoshiyuki

Proceedings of 13th International Conference on Environmental Degradation of Materials in Nuclear Power Systems (CD-ROM), 9 Pages, 2007/00

Crack growth rate (CGR) tests have been conducted with neutron irradiated compact tension (CT) specimens. The CGR tests of 316L and 304L base metals irradiated from 0.516 to 1.07$$times$$10$$^{25}$$n/m$$^{2}$$ (E$$>$$1MeV), and of 316L and 308L weld metals irradiated from 0.523 to 0.541$$times$$10$$^{25}$$n/m$$^{2}$$ (E$$>$$1MeV) were performed using the reversing dc potential drop (DCPD) method under constant load at a few average stress intensity factors (K) and electrochemical corrosion potential (ECP) conditions at 288$$^{circ}$$C in water. CGRs of base metals were increased with increasing neutron fluence. Clear reductions in CGRs of base metals and weld metals were measured with decreasing ECP levels.

Journal Articles

Ripple reduction with ferritic insert in JFT-2M

Shinohara, Koji; Sato, Masayasu; Kawashima, Hisato; Tsuzuki, Kazuhiro; Suzuki, Sadaaki; Urata, Kazuhiro*; Isei, Nobuaki; Tani, Takashi; Kikuchi, Kazuo; Shibata, Takatoshi; et al.

Fusion Science and Technology, 49(2), p.187 - 196, 2006/02

 Times Cited Count:7 Percentile:46.55(Nuclear Science & Technology)

In JFT-2M, the toroidal field ripple was reduced by ferritic insert. Two kinds of ripple reduction were carried out. In the first case, ferritic steel was installed between toroidal field coil and vacuum vessel, just under toroidal field coil, outside vacuum vessel. In the second one, ferritic steel was installed inside vacuum vessel covering almost whole inside wall. The ripple was successfully reduced in the both cases. The temperature increment on the first wall measured by infrared TV was also reduced. A new version of OFMC code was also developed to analyze fast ion behavior in the complex structure of the toroidal field. The TF ripple reduction with ferritic insert in JFT-2M is summarized in this article.

JAEA Reports

Study on Thermal Electric Conversion System for Sodium cooled FBR; Investigation for development of thermoelectric materials and systematic technology

Suzuki, Ryosuke*; Tanabe, Kentaro*; kondo, koki*; Ono, Katsutoshi*; Toda, Shinichi; kasagawa, yusuke; Tamayama, Kiyoshi; Oketani, Kazuhiro*

JNC TY4400 2003-004, 214 Pages, 2003/08


Recently, it has been important to reuse discharged heat energy from present nuclear plants in the view of reduction of environmental burden and improvement of heat efficiency for plant. For practical use in future of sodium cooled FBRs, which are typical high temperature system, this issue must be given priority. The thermal electric conversion system has been applied to the limited uses such as space or military, however, that results show good merits for reliability, maintenance free, and so on. Recently, this technology has been reconsidered in the view of saving energy in general industry. In this study, we made an investigation for applicability of the thermal electric conversion system to sodium cooled FBR as a heat recovery techbnology. Exactly, We have carried out the fundamental research and development for thermoelectric materials and elements, development of modules, and sodium tests with those modules, and then, we acquired the fundamental knowledge to estimate the efficiencies of thermal electric conversion system or modules for a sodium cooled FBR.

JAEA Reports

Applicability of thermoelectric power generation system to Monju

Aizawa, Tatsuhiko*; Yamamoto, Shigeo*; Kim, S.*; Yang, J.*; Iwasako, Yasushi*; Toda, Shinichi; kasagawa, yusuke; Sakata, Hideaki; Oketani, Kazuhiro*

JNC TY4400 2003-003, 100 Pages, 2003/08


How to utilize the waste of heat is one of the most important issues for nuclear engineering. Its technological impact is significant in reduction of environmental burdens and minimization of CO2 emission through nuclear power generation with high efficiency. Research and development for thermoelectric power generation still weighs its importance on the search for high figure-of-merit materials; many engineering issues are still present to be solved toward promising solution to engineering issues are still present to be solved toward promising solution to engineering demand from market. Inthis study, new engineering ideas are proposed to make full use of heat waste via the prototype system for thermoelectric power generation. Sodium loop at the International Cooperation and Technology Development Center of Tsuruga Head Office in JNC was used as a heat source to demonstrate the effectiveness of the developed prototype system. The present research activities are categorized by the following elements.

JAEA Reports

Improvement of the MSG code for the MONJU Evaporators; Additional function of reverse flow calculation on water/steam model and animation for post processing

Toda, Shinichi; Yoshikawa, Shinji; Watanabe, Osamu*; Kishida, Masako*; Oketani, Kazuhiro*

JNC TN4400 2003-005, 106 Pages, 2003/05


The improved version of the MSG code(Multi-dimensional Thermal-hydroulic Analysis Code for Steam Generators) has been released. It has been carried out to improve based on the original version in order to calculate reverse flow on water/steam side, and to animate the post-processing data. To calculate reverse flow locally, modification to set pressure at each divided node point of water/steam region in the helical-coil heat tansfer tubes has been carried out. And the matrix solver has been also improved to treat a problem within practical calculation time against increasing the pressure points. In this case pressure and enthalpy have to be calculated simultaneously, however, it was found out that using the bloci-Jacobean method make a diagonal-dominant matrix, and solve the matriz efficiently with a relaxation method. As the result of calculations of a steady-state condition and a transient of SG blow down with manual tip operation, the improvement on calculation function of the MSG code was confirmed. And an animation function of temperature contour in the sodium shell side as a post procssing has been added. Since the animation is very effective to understand themal-hydraulic behavior on the sodium shell side of the SG, especially in case of transient condition, the analysis and evalution of the calculation results will be enabled to be more quickly and effectively.

Journal Articles

Fast ion loss measurement by IRTV in a reduced ripple experiment with ferritic inserts on JFT-2M

Kawashima, Hisato; Tsuzuki, Kazuhiro; Tani, Takashi; Sato, Masayasu; Suzuki, Sadaaki; Kimura, Haruyuki

Purazuma, Kaku Yugo Gakkai-Shi, 78(9), p.935 - 940, 2002/09

no abstracts in English

Journal Articles

Safety design concepts for ITER-tritium facility; Toward construction in Japan

Ohira, Shigeru; Tada, Eisuke; Hada, Kazuhiko; Neyatani, Yuzuru; Maruo, Takeshi; Hashimoto, Masayoshi*; Araki, Takao*; Nomoto, Kazuhiro*; Tsuru, Daigo; Ishida, Toshikatsu*; et al.

Fusion Science and Technology, 41(3), p.642 - 646, 2002/05

no abstracts in English

73 (Records 1-20 displayed on this page)