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Hayashi, Takumi; Ito, Takeshi*; Kobayashi, Kazuhiro; Isobe, Kanetsugu; Nishi, Masataka
Fusion Engineering and Design, 81(8-14), p.1365 - 1369, 2006/03
Times Cited Count：19 Percentile：75.78(Nuclear Science & Technology)In a fusion reactor, high-level tritiated water of more than GBq/ml will be generated and stored temporally in the various areas. High level tritiated water decomposes by itself and generates hydrogen and oxygen, and becomes to tritiated hydrogen peroxide water, however, effective G-values from tritiated water are different from those obtained 
-ray experiments in our previous report. Furthermore, tritiated water of about 250GBq/ml has been stored for several years safely and checked its characteristics. Using the above experiences, this paper summarizes safety requirements for storage of high-level tritiated water and discusses design issues of the safety storage system. Concerning gaseous species, storage tank should be maintained at negative pressure and purged periodically or constantly to dedicated tritium removal system. Specially, it is important that the G-value of high-level tritiated water is increasing with decreasing the tritium concentration. The pH and ORP (Oxidation Reduction Potential) of tritiated water have been also changed depending on the tritium concentration and maintained for more than several years in glass vessel. High-level tritiated water of more than GBq/ml was acid and became to be corrosive depending on the dissolved species. Large amount of tritiated water will be stored in the various tanks of stainless steel, therefore, it should be monitored so that the liquid situation is maintained not to be corrosive.
Yamada, Hirokazu*; Sato, Satoshi; Mori, Kensuke*; Nagao, Yoshiharu; Takada, Fumiki; Kawamura, Hiroshi
Fusion Engineering and Design, 81(1-7), p.631 - 637, 2006/02
Times Cited Count：1 Percentile：9.40(Nuclear Science & Technology)This study estimated the neutron irradiation effect with 1.5 dpa on the mechanical properties of the SS/SS HIP joint materials jointed in the standard HIP joint condition. Results of this study showed that the HIP process in the standard HIP condition could make SS/SS HIP joint material of which tensile properties was equivalent to that of the SS base material. In addition, the effect of surface roughness at the HIP joint material on the mechanical properties of SS/SS HIP joint material was estimated.
Suzuki, Satoshi; Ezato, Koichiro; Hirose, Takanori; Sato, Kazuyoshi; Yoshida, Hajime; Enoeda, Mikio; Akiba, Masato
Fusion Engineering and Design, 81(1-7), p.93 - 103, 2006/02
Times Cited Count：14 Percentile：66.53(Nuclear Science & Technology)This paper presents an R&D activity on the plasma facing components (PFCs), such as first wall and divertor, for the fusion power plant. The PFCs of the power plant will be subjected to heavy neutron irradiation and high heat/particle flux from plasma during the continuous operation. In the present design of the PFCs, the candidate structural material is a reduced activation ferritic-martensitic steel, F82H, from the viewpoints of low activation and high robustness against neutron irradiation, and the candidate armor material is tungsten from the low sputtering yield and low tritium retention points of view. To realize the PFCs using such materials, JAERI has bee extensively conducting R&Ds on; (1) high performance cooling tube, (2) tungsten armor materials, (3) selection of a bonding technique for F82H and tungsten materials and (4) evaluation of structural integrity. Recent achievements on these R&Ds are presented.
Tsuchiya, Kunihiko; Uchida, Munenori*; Kawamura, Hiroshi
Fusion Engineering and Design, 81(8-14), p.1057 - 1063, 2006/02
Times Cited Count：12 Percentile：61.35(Nuclear Science & Technology)no abstracts in English
Iwai, Yasunori; Yamanishi, Toshihiko; Isobe, Kanetsugu; Nishi, Masataka; Yagi, Toshiaki; Tamada, Masao
Fusion Engineering and Design, 81(1-7), p.815 - 820, 2006/02
Times Cited Count：15 Percentile：68.67(Nuclear Science & Technology)Solid-polymer-electrolyte (SPE) water electrolysis is attractive in electrolytic process of water detritiation system (WDS) in fusion reactors because it can electrolyze liquid waste directly, but radioactive durability of its ion exchange membrane is a key point. Radioactive durability of Nafion, a typical commercial ion exchange membrane, was experimentally investigated using Co-60 irradiation facility and electron beam irradiation facility at Takasaki Radiation Chemistry Research Establishment of JAERI. Nafion is composed of PTFE (Polytetrafluoroethylene) main chain. However the degradation of its mechanical strength by irradiation was significantly distinguished from that of PTFE and no serious damage was observed for its ion exchange capacity up to 530 kGy, the requirement of ITER. Atmospheric effects such as soaking and oxygen on degrading behaviors were discussed from the viewpoint of radical reaction mechanism. Dependencies of operating temperature and radioactive source are also demonstrated in detail.
Kubota, Naoyoshi; Ochiai, Kentaro; Kutsukake, Chuzo; Kondo, Keitaro*; Shu, Wataru; Nishi, Masataka; Nishitani, Takeo
Fusion Engineering and Design, 81(1-7), p.227 - 231, 2006/02
Times Cited Count：5 Percentile：34.96(Nuclear Science & Technology)Hydrogen isotopes play important roles in the fuel recycling, the plasma condition etc. at the surface region of plasma facing components. The Fusion Neutronics Source (FNS) of Japan Atomic Energy Research Institute has started microanalysis studies for fusion components since 2002 by applying the beam analyses. In this study, we have measured tritium depth profiles of TFTR tiles exposed to the deuterium-tritium plasma to reveal the hydrogen isotope behavior at the surface region using some microscopic techniques for material analyses at FNS. As the result of the deuteron nuclear reaction analysis, four kinds of elements; deuterium, tritium, lithium-6 and lithium-7, were identified from the energy spectra. Using the spectra, depth profiles of each element were also calculated. The tritium profile had a peak at 0.5 micron, whereas the deuterium and lithium profiles were uniform from the surface to 1.0 micron depth. In addition, the surface region of the TFTR tile has retained the tritium more than one order of magnitude in the bulk.
Isobe, Kanetsugu; Nakamura, Hirofumi; Kaminaga, Atsushi; Tsuzuki, Kazuhiro; Higashijima, Satoru; Nishi, Masataka; Kobayashi, Yasunori*; Konishi, Satoshi*
Fusion Engineering and Design, 81(1-7), p.827 - 832, 2006/02
Times Cited Count：11 Percentile：58.45(Nuclear Science & Technology)Exhaust gas from JT-60U during experimental operation has been measured with Gas Chromatography (GC), and the gas exhaust characteristic from JT-60U on plasma discharge conditions has been investigated during the JT-60U experimental campaign in 2003-2004. During experimental operation of JT-60U, hydrogen isotope concentration strongly depended on the type of discharges such as high performance, long pulse and so on. On the other hand, impurity species, such as helium, hydrocarbon and carbon oxide, were detected during plasma discharges occasionally. During the experimental operation, plasma disruption remarkably tended to produce high concentration impurities. Glow discharge and Taylor discharge for wall conditioning also produced impurities. In the case of normal plasma, impurity was detected and high performance plasma, such as high 
plasma, tended to produce high concentration impurities. This result indicated that impurities concentration might be higher in the case of normal plasma in ITER, because of its high performance.
Kawamura, Yoshinori; Enoeda, Mikio; Yamanishi, Toshihiko; Nishi, Masataka
Fusion Engineering and Design, 81(1-7), p.809 - 814, 2006/02
Times Cited Count：16 Percentile：70.74(Nuclear Science & Technology)Tritium bred in the solid breeder blanket of a fusion reactor is extracted by passing of a helium sweep gas. Tritium is separated from sweep gas at the blanket tritium recovery system. Palladium membrane diffuser is one of the applicable processes for the blanket tritium recovery system. It is usually applied for hydrogen purification system such as TEP in ITER. However, it has been reported that the rate controlling step changes at lower hydrogen pressure such as the blanket sweep gas condition, and discussion about application for the blanket sweep gas condition is not enough. Recently, conceptual design of the demonstration reactor, named "DEMO2001", has been proposed from JAERI. In this report, the application of the Pd diffuser for the blanket sweep gas condition is discussed based on the condition of DEMO 2001.
Kobayashi, Kazuhiro; Hayashi, Takumi; Nishi, Masataka; Oya, Yasuhisa*; Okuno, Kenji*
Fusion Engineering and Design, 81(8-14), p.1379 - 1384, 2006/02
Times Cited Count：5 Percentile：34.96(Nuclear Science & Technology)In facilities of ITER, various construction materials are possibly exposed by tritium during periodical maintenances and an accident. It is required to establish the effective surface decontamination methods for the above construction materials of ITER. In tritium decontaminating, so-called "soaking" effect is important. This effect is based on sorption of tritiated water on the materials and subsequent desorption from them. In order to obtain and summarize data on the amount of tritium adsorption on the various materials, a series of tritiated water vapor exposure experiments have been carried out as a function of time. The amounts of tritium adsorption on the materials saturated almost within the period from several weeks to 1 month. The adsorption rate of the epoxy was found to be the largest. In the exposure time less than 2 hrs, the adsorption coefficients for the examined materials were found to be in the same order as those reported by F.Ono. It will be also discussed from viewpoint of kinetics for adsorption and desorption.
Yamauchi, Michinori*; Hori, Junichi*; Ochiai, Kentaro; Sato, Satoshi; Nishitani, Takeo; Kawasaki, Hiromitsu*
Fusion Engineering and Design, 81(8-14), p.1577 - 1582, 2006/02
Times Cited Count：1 Percentile：9.40(Nuclear Science & Technology)no abstracts in English
Ochiai, Kentaro; Nakao, Makoto*; Hori, Junichi*; Sato, Satoshi; Yamauchi, Michinori*; Ishioka, Noriko; Nishitani, Takeo
Fusion Engineering and Design, 81(8-14), p.1459 - 1464, 2006/02
Times Cited Count：2 Percentile：16.48(Nuclear Science & Technology)The IFMIF consists of two 40 MeV deuteron linear accelerators with 125 mA beam current each. The structure materials of the accelerators are activated with high energetic deuteron. To measure the activation cross sections with 
Al, 
Cu, W, V, Ni, Fe, and Ta samples irradiated with 22-40 MeV deuteron beams, we have carried out the irradiation experiment of the main elements of the IFMIF candidate materials by using the deutron beam of the AVF cyclotron of the TIARA facility in JAERI/Takasaki.
Kondo, Keitaro; Takagi, Satoshi*; Murata, Isao*; Miyamaru, Hiroyuki*; Takahashi, Akito*; Kubota, Naoyoshi; Ochiai, Kentaro; Nishitani, Takeo
Fusion Engineering and Design, 81(8-14), p.1527 - 1533, 2006/02
Times Cited Count：14 Percentile：68.67(Nuclear Science & Technology)In a fusion reactor development, double-differential charged-particle emission cross sections(DDXc) are necessary to estimate nuclear heating and material damages of candidate materials irradiated with neutrons. Especially in light nuclei such as Be, Li, and C, nuclear reactions are complicated and difficult to estimate energy spectra of emitted particles based only on theoretical calculations Therefore development of a new technique for precise measurements of DDXc is quite important. Recently we successfully developed a new spectrometer for measurement of DDXc using a pencil-beam DT neutron source of FNS in JAERI. In the present study we carried out measurements of DDXc of 
Be, 
C, 
F, and Al using the spectrometer. The present technique was valid from the result of measurement for the Al(n,x
) reactions. Slight differences appeared between measured data and evaluation or previous experimental values for Be(n,x) reactions at backward scattering angle and in lower energy region.
Yoshida, Hajime; Yokoyama, Kenji; Taniguchi, Masaki; Ezato, Koichiro; Suzuki, Satoshi; Akiba, Masato
Fusion Engineering and Design, 81(1-7), p.361 - 366, 2006/02
Times Cited Count：2 Percentile：16.48(Nuclear Science & Technology)A 100 V level, high-flux, large area and steady-state ion beam acceleration has been developed for the investigation of the interactions between fusion edge plasmas and plasma facing materials. We have developed the new electrodes and installed them in the Super Low Energy Ion Source (SLEIS). Obtained hydrogen ion flux is comparable to those of conventional high-flux ion source (
1020 H/m
s), though the accelerated voltage is extremely low (60-200 eV). This 100 V level ion beam acceleration will be useful to investigate the plasma wall interaction in divertor.
Inoue, Takashi; Hanada, Masaya; Kashiwagi, Mieko; Nishio, Satoshi; Sakamoto, Keishi; Sato, Masayasu; Taniguchi, Masaki; Tobita, Kenji; Watanabe, Kazuhiro; DEMO Plant Design Team
Fusion Engineering and Design, 81(8-14), p.1291 - 1297, 2006/02
Times Cited Count：13 Percentile：63.92(Nuclear Science & Technology)Requirement and technical issues of the neutral beam inejctor (NBI) is discussed for fusion DEMO plant. The NBI for the fusion DEMO plant should be high efficiency, high energy and high reliability with long life. From the view point of high efficiency, use of conventional electrostatic accelerator is realistic. Due to operation under radiation environment, vacuum insulation is essential in the accelerator. According to the insulation design guideline, it was clarified that the beam energy of 1.5
2 MeV is possible in the accelerator. Development of filamentless, and cesium free ion source is required, based on the existing high current/high current density negative ion production technology. The gas neutralization is not applicable due to its low efficiency (60%). R&D on an advanced neutralization scheme such as plasma neutralization (efficiency: 80%) is required. Recently, development of cw high power semiconductor laser is in progress. The paper shows a conceptual design of a high efficiency laser neutralizer utilizing the new semiconductor laser array.
TiO
pebbles with different diametersTsuchiya, Kunihiko; Kawamura, Hiroshi; Tanaka, Satoru*
Fusion Engineering and Design, 81(8-14), p.1065 - 1069, 2006/02
Times Cited Count：11 Percentile：58.45(Nuclear Science & Technology)no abstracts in English
Ezato, Koichiro; Suzuki, Satoshi; Dairaku, Masayuki; Akiba, Masato
Fusion Engineering and Design, 81(1-7), p.347 - 354, 2006/02
Times Cited Count：13 Percentile：63.92(Nuclear Science & Technology)no abstracts in English
Nishi, Masataka; Yamanishi, Toshihiko; Hayashi, Takumi; DEMO Plant Design Team
Fusion Engineering and Design, 81(1-7), p.745 - 751, 2006/02
Times Cited Count：33 Percentile：88.41(Nuclear Science & Technology)The fusion DEMO plant is under designing at JAERI as a fusion machine following ITER, and it is designed with long-term steady operation and tritium breeding blanket in which more tritium is produced than consumption. Therefore, proper tritium accountancy control concept should be discussed and developed for its safety and operation. From the viewpoint of regulation for the radioisotopes, at first, it will be suitable to divide facilities of the fusion DEMO plant into three accountancy control blocks, that is, (1) the contaminated waste management facility, (2) the long term tritium storage facility, and (3) the fuel processing plant. In each block, tritium amount of receipt and delivery should be carefully accounted. The fuel processing plant involves tritium production in the blanket, therefore proper accounting method for produced tritium should be established. Furthermore, dynamic accountancy is indispensable to the fuel processing plant to monitor tritium inventory distribution for safety and optimum system control in addition to the accountancy under regulation.
Tsuchiya, Katsuhiko; Akiba, Masato; Azechi, Hiroshi*; Fujii, Tsuneyuki; Fujita, Takaaki; Fujiwara, Masami*; Hamamatsu, Kiyotaka; Hashizume, Hidetoshi*; Hayashi, Nobuhiko; Horiike, Hiroshi*; et al.
Fusion Engineering and Design, 81(8-14), p.1599 - 1605, 2006/02
Times Cited Count：1 Percentile：9.40(Nuclear Science & Technology)no abstracts in English
Takahashi, Koji; Kobayashi, Noriyuki*; Kasugai, Atsushi; Sakamoto, Keishi
Fusion Engineering and Design, 81(1-7), p.281 - 287, 2006/02
Times Cited Count：5 Percentile：34.96(Nuclear Science & Technology)In the ITER, an EC H&CD steering antenna mirror was designed to reflect eight or nine 1MW-wave beams. The cross-section and thickness of the mirror are 250
360 mm and 50mm, respectively. The thermal and stress analysis under the ITER condition show that the copper alloy(DSCu) mirror with stainless steel cooling tubes inside is considered acceptable. The EC H&CD antenna system for the ITER must have a dog-legged transmission lines so as to protect the diamond windows or superconducting magnets of a tokamak. A 90
miter bend, which consists of waveguides and a reflection mirror, is required to make the structure. The mock-up of the mirror based on the ITER design was fabricated and the high power transmission experiment was carried out. The mm-wave transmission with power/pulse length 450kW/5.0sec, was demonstrated. The ohmic loss is estimated to be 0.2%, which agrees with the calculation based on electrical resistivity of DSCu 2.010
m.
Isono, Takaaki; Koizumi, Norikiyo; Okuno, Kiyoshi; Kurihara, Ryoichi; Nishio, Satoshi; Tobita, Kenji
Fusion Engineering and Design, 81(8-14), p.1257 - 1261, 2006/02
Times Cited Count：6 Percentile：39.85(Nuclear Science & Technology)In order to realize an economically competitive power generation system, generation of a higher field is required. Toroidal Field (TF) coils of fusion DEMO plant at JAERI are required to generate magnetic field of 16 to 20 T. To realize this high field, advanced superconducting materials, such as Nb
Al and high temperature superconductor (HTS), are considered. HTS has enough performance in a 20-T field at 4 K, and a forced-cooled type HTS conductor using a silver alloy sheathed Bi-2212 round wire has been proposed. Required areas of superconductor, structure, stabilizer, coolant and insulator in the cross section of coil winding have been calculated. However, there are many technical issues to be solved, such as accurate temperature control during heat treatment in an atmosphere of oxygen. On the other hand, a large coil using NbAl has been developed by JAERI, and major technology to fabricate a 16-T NbAl coil was developed. Validity and issues of grading the winding area are discussed, and there is a possibility to increase a field up to around 17 T using the method.
