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Journal Articles

Introduction to radiation physics; Third revised edition

Tada, Junichiro*; Nakashima, Hiroshi; Hayano, Ryugo*; Kobayashi, Hitoshi*; Asano, Yoshihiro*

Wakariyasui Hoshasen Butsurigaku; Kaitei 3-Han, 305 Pages, 2018/03

This book is an introduction to radiation physics. Under the concept of "linking physics of high school and radiation physics" for readers with high school graduation degree, we are doing simple commentary on the basis of qualitative explanation as much as possible. This book begins with "What is Radiation Physics", and consists of 12 chapters, including introductory special relativity, introductory quantum theory, structures of atoms and nuclei, radiations, radioactivity, interactions between radiation and matter, accelerators, radiation dose and so on.

JAEA Reports

Annual report on the effluent control of low level liquid waste in Nuclear Fuel Cycle Engineering Laboratories FY2014

Watanabe, Hitoshi; Nakano, Masanao; Fujita, Hiroki; Kono, Takahiko; Inoue, Kazumi; Yoshii, Hideki*; Otani, Kazunori*; Hiyama, Yoshinori*; Kikuchi, Masaaki*; Sakauchi, Nobuyuki*; et al.

JAEA-Review 2015-030, 115 Pages, 2015/12

JAEA-Review-2015-030.pdf:25.28MB

Based on the regulations (the safety regulation of Tokai reprocessing plant, the safety regulation of nuclear fuel material usage facilities, the radiation safety rule, the regulation about prevention from radiation hazards due to radioisotopes, which are related with the nuclear regulatory acts, the local agreement concerning with safety and environment conservation around nuclear facilities, the water pollution control law, and bylaw of Ibaraki prefecture), the effluent control of liquid waste discharged from the Nuclear Fuel Cycle Engineering Laboratories of Japan Atomic Energy Agency has been performed. This report describes the effluent control results of the liquid waste in the fiscal year 2014. In this period, the concentrations and the quantities of the radioactivity in liquid waste discharged from the reprocessing plant, the plutonium fuel fabrication facilities, and the other nuclear fuel material usage facilities were much lower than the limits authorized by the above regulations.

Journal Articles

Development of a dynamic CT system for neutron radiography and consecutive visualization of three-dimensional water behavior in a PEFC stack

Murakawa, Hideki*; Hashimoto, Michinori*; Sugimoto, Katsumi*; Asano, Hitoshi*; Takenaka, Nobuyuki*; Mochiki, Koichi*; Yasuda, Ryo

Nihon Kikai Gakkai Rombunshu, B, 77(784), p.2255 - 2262, 2011/12

Journal Articles

Evaluation of water distribution in a small operating fuel cell using neutron color image intensifier

Yasuda, Ryo; Nitto, Koichi*; Konagai, Chikara*; Shiozawa, Masahiro*; Takenaka, Nobuyuki*; Asano, Hitoshi*; Murakawa, Hideki*; Sugimoto, Katsumi*; Nojima, Takehiro; Hayashida, Hirotoshi; et al.

Nuclear Instruments and Methods in Physics Research A, 651(1), p.268 - 272, 2011/09

 Times Cited Count:7 Percentile:51.85(Instruments & Instrumentation)

Neutron radiography is one of useful tools to visualize water behavior in fuel cells under operation. In order to observe the detailed information about the water distribution in MEA and GDL in fuel cells, a high spatial resolution and high sensitivity neutron imaging system are required. We developed an imaging system using the neutron color imaging intensifier and continuously observed water distribution in operating a fuel cell. By using the system, a small type fuel cell under operation was continuously observed at the TNRF in every 20 sec. In the results, the water area was appeared from GDL and MEA, and expanded to the channel of the cathode side. On the other hand, voltage was gradually reduced with the operation time, and steeply dropped. It is considered that voltage drop was caused by blockage of gas flow due to the piling up water in the channel of the cathode side.

Journal Articles

Measurements of water distribution in through-plane direction of PEFC by using neutron radiography

Murakawa, Hideki*; Wada, Daisuke*; Sugimoto, Katsumi*; Asano, Hitoshi*; Takenaka, Nobuyuki*; Yasuda, Ryo

Nuclear Instruments and Methods in Physics Research A, 651(1), p.286 - 289, 2011/09

 Times Cited Count:9 Percentile:60.25(Instruments & Instrumentation)

Journal Articles

Visualization of dynamic 3-D water behavior in polymer electrolyte fuel cell by using neutron image intensifier

Takenaka, Nobuyuki*; Asano, Hitoshi*; Sugimoto, Katsumi*; Murakawa, Hideki*; Hashimoto, Michinori*; Shindo, Noritaka*; Mochiki, Koichi*; Yasuda, Ryo

Nuclear Instruments and Methods in Physics Research A, 651(1), p.277 - 281, 2011/09

 Times Cited Count:5 Percentile:41.32(Instruments & Instrumentation)

Journal Articles

Effect of water distributions on performances of JARI standard PEFC by using neutron radiography

Murakawa, Hideki*; Ueda, Tadanobu*; Yoshida, Takehisa*; Sugimoto, Katsumi*; Asano, Hitoshi*; Takenaka, Nobuyuki*; Mochiki, Koichi*; Iikura, Hiroshi; Yasuda, Ryo; Matsubayashi, Masahito

Nuclear Instruments and Methods in Physics Research A, 605(1-2), p.127 - 130, 2009/06

 Times Cited Count:22 Percentile:82.31(Instruments & Instrumentation)

Journal Articles

Novel UV-induced photografting process for preparing poly(tetrafluoroethylene)-based proton-conducting membranes

Asano, Masaharu; Chen, J.; Maekawa, Yasunari; Sakamura, Takahiro*; Kubota, Hitoshi*; Yoshida, Masaru

Journal of Polymer Science, Part A; Polymer Chemistry, 45(13), p.2624 - 2637, 2007/07

A novel process comprising UV-induced photografting of styrene into polytetrafluoroethylene (PTFE) films and subsequent sulfonation has been developed for preparing proton-conducting membranes. The significance of this process is that the polystyrene can graft throughout the PTFE films. Even through the degree of grafting was lower than 10 %, the proton conductivity of the newly prepared membranes can reach a value similar to Nafion. In comparison with $$gamma$$-ray radiation grafting, UV photografting is less damaging to the membranes because significant degradation of the PTFE main chains can be avoided.

Journal Articles

Comparative study on the preparation and properties of radiation-grafted polymer electrolyte membranes based on fluoropolymer films

Chen, J.; Septiani, U.*; Asano, Masaharu; Maekawa, Yasunari; Kubota, Hitoshi*; Yoshida, Masaru

Journal of Applied Polymer Science, 103(3), p.1966 - 1972, 2007/03

 Times Cited Count:19 Percentile:53.17(Polymer Science)

In this study, ETFE and PVDF films, together with the crosslinked PTFE (cPTFE) films have been compared on the basis of their preparation and properties of radiation-grafted polymer electrolyte membranes (PEM). The proton conductivity and chemical stability of the three types of membranes with the similar ion exchange capacity near 1.0 mmolg$$^{-1}$$ were investigated and discussed in detail. Although the ETFE-based PEM was relatively more stable, its proton conductivity was lower than those of the PVDF- and cPTFE-based membranes. On the other hand, the cPTFE-based membrane showed the significantly higher proton conductivity, but its chemical stability was shorter than that of the ETFE-based membrane. The difference in the preparation and properties of the PEMs was due to the difference in the crystallinity and intrinsic properties of the base films.

Journal Articles

Proton exchange membranes for fuel cell applications prepared by ion track technology

Yamaki, Tetsuya; Kozone, Yuichi*; Hiroki, Akihiro; Hosoi, Katsuhiko*; Asano, Masaharu; Kubota, Hitoshi*; Yoshida, Masaru

Denki Kagaku Oyobi Kogyo Butsuri Kagaku, 75(2), p.175 - 178, 2007/02

 Times Cited Count:9 Percentile:21.7(Electrochemistry)

Proton exchange membranes for use in fuel cells were prepared our original ion-track technology, which involves (1) the swift heavy ion irradiation of polyvinylidene fluoride films and subsequent chemical etching to obtain cylindrical pores, and (2) the filling of proton-conducting polymer chains into the etched pores by $$gamma$$-ray-induced graft polymerization. We found that the membranes possessed one-dimensional straight proton conducting pathways parallel to the ion-beam incident axis. Such restricted structures probably led to less water uptake and lower methanol permeability compared to a commercially-available Nafion membrane.

Journal Articles

Influence of pre-irradiation atmosphere on the properties of polymer electrolyte membranes prepared using radiation grafting method

Septiani, U.*; Chen, J.; Asano, Masaharu; Maekawa, Yasunari; Yoshida, Masaru; Kubota, Hitoshi*

Journal of Materials Science, 42(4), p.1330 - 1335, 2007/02

 Times Cited Count:16 Percentile:49.4(Materials Science, Multidisciplinary)

The influence of pre-irradiation atmosphere, argon and air, on radiation grafting of styrene into poly(ethylene-co-tetrafluoroethylene) (ETFE) films and the properties of the ETFE-based radiation-grafted polymer electrolyte membranes were investigated. The preparation and properties of the membranes were found to be strongly influenced by the $$gamma$$-ray pre-irradiation atmosphere. The proton conductivity was measured in its water-saturated state at 25$$^{circ}$$C, and the membrane durability was tested in a 3 % H$$_{2}$$O$$_{2}$$ aqueous solution at 60$$^{circ}$$C. The proton conductivity of the membrane prepared by pre-irradiation under air was higher than that of the membrane prepared under argon with the same ion exchange capacity level. However, the durability of the former was considerably lower than that of the latter. For instance, the membrane with an ion exchange capacity of about 1.0 mmolg-1 prepared under argon was twice as durable as that prepared under air. It was considered that the lower durability of the membrane prepared by pre-irradiation under air was because of the unstable ether bond introduced between the graft chains and the backbone chains. : polymer electrolyte membrane (PEM); radiation grafting; styrene; durability; ETFE

Journal Articles

Preparation of ETFE-based fuel cell membranes using UV-induced photografting and electron beam-induced crosslinking techniques

Chen, J.; Asano, Masaharu; Maekawa, Yasunari; Sakamura, Takahiro*; Kubota, Hitoshi*; Yoshida, Masaru

Journal of Membrane Science, 283(1-2), p.373 - 379, 2006/10

 Times Cited Count:23 Percentile:59.84(Engineering, Chemical)

A novel process comprising UV-induced photografting of styrene into poly(tetrafluoroethylene-co-ethylene) (ETFE) films in vapor and liquid phases, followed by electron beam-induced crosslinking has been developed for preparing polymer electrolyte membranes. The significance of this process is that the photografted polystyrene chains can completely penetrate into the base ETFE film; the membranes show proton conductibility available for fuel cell applications. On one hand, the proton conductivity of the liquid-phase photografted electrolyte membranes is higher than the vapor-phase one, and is anisotropic in the surface and thickness directions. On the other hand, radiation-induced crosslinking greatly improves the chemical stability of the resultant fuel cell membranes, and maintains the surface concentration of sulfonic acid groups at its higher level.

Journal Articles

Nano-structure controlled polymer electrolyte membranes for fuel cell applications prepared by ion beam irradiation

Yamaki, Tetsuya; Kozone, Yuichi; Hiroki, Akihiro; Asano, Masaharu; Kubota, Hitoshi*; Yoshida, Masaru

ECS Transactions, 3(1), p.103 - 112, 2006/00

Fluoropolymer-based electrolyte membranes for water electrolyzers and fuel cells were prepared by using heavy ion beams from the cyclotron accelerator. The preparation method for these so-called "nano-scale structure-controlled membranes" involves (1) the swift heavy ion irradiation of polyvinylidene fluoride films and subsequent chemical etching to obtain cylindrical pores with a diameter of 100 nm, and (2) the filling of proton-conducting polymer chains into the etched pores by $$gamma$$-ray-induced graft polymerization. The proton transport only in the thickness direction was observed for the resulting membranes with controlled ion exchange capacities, indicating the formation of one-dimensional straight proton-conducting pathways parallel to the ion-beam incident axis. The membranes exhibited a lower water uptake and reduced methanol permeability compared to commercially-available Nafion probably due to the restricted structures.

Journal Articles

Preparation of fuel cell membranes by photografting in vapor and liquid phases

Chen, J.; Asano, Masaharu; Maekawa, Yasunari; Sakamura, Takahiro*; Kubota, Hitoshi*; Yoshida, Masaru

Electrochemical and Solid-State Letters, 9(5), p.G184 - G186, 2006/00

 Times Cited Count:8 Percentile:32.82(Electrochemistry)

UV radiation-induced photografting of styrene into ETFE films for the preparation of fuel cell membranes was carried out. The proton conductivity in thickness direction of membranes prepared by the vapor- and liquid-phase photografting can reach as high as 0.065 and 0.087 S/cm, respectively. The higher conductivity in the liquid-phase grafting is close to the homogeneity of graft chain distribution in the membrane.

Journal Articles

Polytetrafluoroethylene-based proton-conducting membranes prepared by ultraviolet-induced photografting

Chen, J.; Asano, Masaharu; Maekawa, Yasunari; Sakamura, Takahiro*; Kubota, Hitoshi*; Yoshida, Masaru

Electrochemical and Solid-State Letters, 9(11), p.G326 - G329, 2006/00

 Times Cited Count:5 Percentile:23.27(Electrochemistry)

A novel process comprising UV-induced photografting of styrene into PTFE films and subsequent sulfonation has been developed for preparing proton-conducting membranes. The significance of this process is that the graft chains can penetrate throughout the PTFE base films; the resultant sulfonated electrolyte membrane with a low degree of grafting near 7% shows higher proton conductibility and better mechanical properties, similar to those of Nafion membrane. Furthermore, the performances of the UV-photografted electrolyte membranes are better as compared to those of the radiation grafted electrolyte membranes.

Journal Articles

Preparation of proton exchange membranes based on crosslinked polytetrafluoroethylene for fuel cell applications

Yamaki, Tetsuya; Kobayashi, Kazuhiro; Asano, Masaharu; Kubota, Hitoshi*; Yoshida, Masaru

Polymer, 45(19), p.6569 - 6573, 2004/09

 Times Cited Count:56 Percentile:83.55(Polymer Science)

We prepared proton exchange membranes by the $$gamma$$-ray-induced post grafting of styrene into crosslinked polytetrafluoroethylene (PTFE) films and subsequent sulfonation. The degree of grafting was controlled in the range of 7-75% by the crosslinking density of the PTFE matrix as well as the grafting conditions. Under our preparation conditions, the films at the grafting yield of $$geq$$30% were found to produce ion exchange membranes with a homogeneous distribution of sulfonic acid groups. The resulting membranes showed a large ion exchange capacity up to 2.9 meq g$$^{-1}$$, which exceeded the performance of commercially-available perfluorosulfonic acid films such as Nafion; nevertheless, they appeared to be dimensionally stable in water. These should undoubtedly result from the use of the crosslinked PTFE films as graft substrates and make our ion exchange membranes promising for applications to polymer electrolyte fuel cells.

Journal Articles

Radiation grafting of styrene into crosslinked PTEE films and subsequent sulfonation for fuel cell applications

Yamaki, Tetsuya; Asano, Masaharu; Maekawa, Yasunari; Morita, Yosuke; Suwa, Takeshi; Chen, J.*; Tsubokawa, Norio*; Kobayashi, Kazuhiro*; Kubota, Hitoshi*; Yoshida, Masaru

Radiation Physics and Chemistry, 67(3-4), p.403 - 407, 2003/08

 Times Cited Count:76 Percentile:97.3(Chemistry, Physical)

no abstracts in English

Journal Articles

Preparation of crosslinked fluoropolymer electrolyte membranes for use in fuel cells and then investigated their structural properties

Inoue, Yutaka; Kobayashi, Kazuhiro; Yamaki, Tetsuya; Asano, Masaharu; Kubota, Hitoshi*; Yoshida, Masaru

Dai-2-Kai 21-Seiki Rengo Shimpojiumu; Kagaku Gijutsu To Ningen Rombunshu, p.257 - 260, 2003/00

We prepared crosslinked fluoropolymer electrolyte membranes for use in fuel cells and then investigated their structural properties by X-ray diffraction (XRD) analysis. The radiation-induced grafting of styrene into crosslinked polytetrafluoroethylene (PTFE) films and subsequent sulfonation enabled us to obtain the electrolyte membrane with a sufficient ion exchange capacity, which exceeds that of the commercially-available film, Nafion. As the crosslinking and styrene grafting reactions proceeded, the size of the PTFE crystallites in the film became smaller, thereby decreasing the film crystallinity. Interestingly, in contrast to Nafion, the resulting sulfonated membranes were found to have high crystallinity.

Journal Articles

Permeation of p-nitrophenol through N-isopropylacrylamide-grafted etched-track membrane close to $$theta$$-point temperature

Hiroki, Akihiro*; Yoshida, Masaru; *; Asano, Masaharu; N.Reber*; R.Spohr*; Kubota, Hitoshi*; Katakai, Ryoichi*

Radiat. Eff. Defects Solids, 147, p.165 - 175, 1999/00

no abstracts in English

Journal Articles

Simultaneously occurring process of radiation-induced polymerization, crosslinking, and degradation of N-isopropylacrylamide

Yoshida, Masaru; *; Asano, Masaharu; Suwa, Takeshi; Kubota, Hitoshi*; Katakai, Ryoichi*

J. Polym. Sci., Part A, 35, p.3075 - 3077, 1997/00

no abstracts in English

47 (Records 1-20 displayed on this page)