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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：76.30(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.
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：35.34(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.
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：35.34(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.
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：58.92(Nuclear Science & Technology)no abstracts in English
Tsuchiya, Kunihiko; Uchida, Munenori*; Kawamura, Hiroshi
Fusion Engineering and Design, 81(8-14), p.1057 - 1063, 2006/02
Times Cited Count：12 Percentile：61.76(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：69.07(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.
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：9.58(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.
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：87.74(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：9.58(Nuclear Science & Technology)no abstracts in English
Yamanishi, Toshihiko; Iwai, Yasunori; Kawamura, Yoshinori; Nishi, Masataka
Fusion Engineering and Design, 81(1-7), p.797 - 802, 2006/02
Times Cited Count：9 Percentile：52.28(Nuclear Science & Technology)no abstracts in English
Luo, G.; Shu, Wataru; Nishi, Masataka
Fusion Engineering and Design, 81(8-14), p.957 - 962, 2006/02
Times Cited Count：67 Percentile：96.53(Nuclear Science & Technology)The influence of blistering on deuterium retention in W was investigated using the newly established plasma generator with controllable incident energies ranging from 100 eV down to around 10 eV and incident flux of 110
D/m/s. The retention in the irradiated samples was measured using a thermal desorption spectrometer (TDS) at a ramping rate of 5 C/s. The results indicate that only one peak appears in each spectrum, with the peak temperatures ranging from 500 until 850 C, much higher than those from the trapping sites like vacancies, grain boundaries, dislocation loops, or impurities, implying probably a direct origin from the molecules existing inside blisters, voids/bubbles. Significant decrease in the retention at a certain incident fluence after blister appearance was observed and attributed to rupturing of the blisters, consistent with the limited size and increasing number of the blisters with increasing the incident fluence, as observed by means of SEM.
Shu, Wataru; Matsuyama, Masao*; Suzuki, Takumi; Nishi, Masataka
Fusion Engineering and Design, 81(1-7), p.803 - 808, 2006/02
Times Cited Count：12 Percentile：61.76(Nuclear Science & Technology)In this work, the counting rate of bremsstrahlung X-rays was measured against the tritium partial pressure in two mixed gases diluted with helium or hydrogen. Subsequently, the counting rate was also measured against total pressure for T-He mixture at a constant tritium partial pressure of 93 Pa or 1.3 kPa. For both mixtures, the counting rate of bremsstrahlung X-rays decreased linearly with the decreasing tritium partial pressure when the total pressure is smaller than about 10 kPa. At higher pressures, the deviation from the linear relationship appeared due to absorption of beta-particles in the gas phase, and this can be decreased by some commercially available arrangements. On the other hand, the counting rate of bremsstrahlung X-rays depended only upon the tritium partial pressure when absorption of beta-particles in the gas phase is negligibly small. The results obtained show that this method of tritium monitoring is very promising for the fuel processing system of fusion reactors, especially for tritium recovery system of breeding blankets.
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：40.23(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.
Nishitani, Takeo; Yamauchi, Michinori*; Nishio, Satoshi; Wada, Masayuki*
Fusion Engineering and Design, 81(8-14), p.1245 - 1249, 2006/02
Times Cited Count：14 Percentile：66.95(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：16.63(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：66.95(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.
Enoeda, Mikio; Akiba, Masato; Tanaka, Satoru*; Shimizu, Akihiko*; Hasegawa, Akira*; Konishi, Satoshi*; Kimura, Akihiko*; Koyama, Akira*; Sagara, Akio*; Muroga, Takeo*
Fusion Engineering and Design, 81(1-7), p.415 - 424, 2006/02
Times Cited Count：63 Percentile：96.09(Nuclear Science & Technology)no abstracts in English
Sakamoto, Keishi; Takahashi, Koji; Kasugai, Atsushi; Minami, Ryutaro; Kobayashi, Noriyuki*; Nishio, Satoshi; Sato, Masayasu; Tobita, Kenji
Fusion Engineering and Design, 81(8-14), p.1263 - 1270, 2006/02
Times Cited Count：6 Percentile：40.23(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：64.48(Nuclear Science & Technology)no abstracts in English
TiO heated at high temperature under various conditionsHoshino, Tsuyoshi; Yasumoto, Masaru*; Tsuchiya, Kunihiko; Hayashi, Kimio; Nishimura, Hidetoshi*; Suzuki, Akihiro*; Terai, Takayuki*
Fusion Engineering and Design, 81(1-7), p.555 - 559, 2006/02
Times Cited Count：19 Percentile：76.30(Nuclear Science & Technology)no abstracts in English
