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Negishi, Hitoshi; Kamide, Hideki; Maeda, Seiichiro; Nakamura, Hirofumi; Abe, Tomoyuki
Nihon Genshiryoku Gakkai-Shi ATOMO
, 62(8), p.438 - 441, 2020/08
Prototype Fast Breeder Reactor, Monju, was under decommission since April, 2018. It is the first time for Japan to make a sodium cooled reactor into decommission. It is significant work and will take 30 years. The Monju has provided wide spectrum and huge amount of findings and knowledge, e.g., design, R&D, manufacturing, construction, and operation up to 40% of full power over 50 years of development history. It is significant to utilize such findings and knowledge for the development and commercialization of a fast rector in Japan.
Isobe, Kanetsugu; Kawamura, Yoshinori; Iwai, Yasunori; Oyaizu, Makoto; Nakamura, Hirofumi; Suzuki, Takumi; Yamada, Masayuki; Edao, Yuki; Kurata, Rie; Hayashi, Takumi; et al.
Fusion Engineering and Design, 98-99, p.1792 - 1795, 2015/10
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)Activities on Broader Approach (BA) were started in 2007 on the basis of the Agreement between the Government of Japan and the EURATOM. The period of BA activities consist of Phase1 and Phase2 dividing into Phase 2-1 (2010-2011), Phase 2-2 (2012-2013) and Phase 2-3 (2014-2016). Tritium technology was chosen as one of important R&D issues to develop DEMO plant. R&D activities of tritium technology on BA consist of four tasks. Task-1 is to prepare and maintain the tritium handling facility in Rokkasho BA site in Japan. Task 2, 3 and 4 are main R&D activities for tritium and these are focused on: Task-2) Development of tritium accountancy technology, Task-3) Development of basic tritium safety research, Task-4) Tritium durability test. R&D activities of tritium technology in Phase 2-2 were underway successfully and closed in 2013.
Hayashi, Takumi; Nakamura, Hirofumi; Kawamura, Yoshinori; Iwai, Yasunori; Isobe, Kanetsugu; Yamada, Masayuki; Suzuki, Takumi; Kurata, Rie; Oyaizu, Makoto; Edao, Yuki; et al.
Fusion Science and Technology, 67(2), p.365 - 370, 2015/03
Times Cited Count：1 Percentile：9.74(Nuclear Science & Technology)Ishimi, Akihiro; Katsuyama, Kozo; Nakamura, Hirofumi; Asaka, Takeo; Furuya, Hirotaka
Nuclear Technology, 189(3), p.312 - 317, 2015/03
Times Cited Count：4 Percentile：33.25(Nuclear Science & Technology)A high resolution X-ray CT technique was developed, which made it possible to obtain fine X-ray CT images of an irradiated fuel assembly. In addition, the density distributions in the irradiated MOX fuel pellet could be continually measured, using the relationship between the densities and CT values. These results were compared to the one obtained by metallographical method. As results, it was found that the relative change of radial density distributions in the irradiated fuel pellet can be measured more accurately by the X-ray CT technique than by the metallographical examination.
Hayashi, Takumi; Isobe, Kanetsugu; Nakamura, Hirofumi; Kobayashi, Kazuhiro; Oya, Yasuhisa*; Okuno, Kenji*; Oyaizu, Makoto; Edao, Yuki; Yamanishi, Toshihiko
Fusion Engineering and Design, 89(7-8), p.1520 - 1523, 2014/10
Times Cited Count：1 Percentile：8.88(Nuclear Science & Technology)Tritium confinement is the most important safety issue in the fusion reactor. Tritium behavior on the water metal boundary is very important to design tritium plant with breading blanket system using cooling water. A series of tritium permeation experiment into pressurized water or water vapor jacket with He or Ar have been performed through pure iron piping with/without 7 micro-meter gold plating, which contained about 1 kPa of pure tritium gas at 423 K, with monitoring the chemical forms of tritium. Also, deuterium permeation experiments from heavy water vessel through various metal piping, such as pure iron (Fe), nickel (Ni), stainless steel (SS304), and pure iron with 10 micro-meter gold plating, were performed at 573 K and at 15 MPa. Recently, using the above heavy water system, we have succeeded to detect simultaneous hydrogen isotopes transfer from and to the metal surface by introducing H
gas to the metal piping after stabilized deuterium permeation was detected.
Yamanishi, Toshihiko; Nakamura, Hirofumi; Kawamura, Yoshinori; Iwai, Yasunori; Isobe, Kanetsugu; Oyaizu, Makoto; Yamada, Masayuki; Suzuki, Takumi; Hayashi, Takumi
Fusion Engineering and Design, 87(5-6), p.890 - 895, 2012/08
Times Cited Count：1 Percentile：10.14(Nuclear Science & Technology)In JAEA, the tritium processing and handling technologies have been studied at TPL. The main basic R&D activities in this field are: the tritium processing technology for the blanket recovery system; the tritium behavior in a confinement; and detritiation and decontamination. The R&D for tritium processing and handling technologies to a demonstration reactor (DEMO) are also planned to be carried out in the Broader Approach (BA) program in Japan by JAEA with Japanese universities. The ceramic electrolysis cell has been studied as a tritium processing method for the blanket system. The permeation behavior of tritium through pure iron into the gas containing water vapor has been studied. As for the behavior of high concentration tritium water, it was observed that the formation of the oxidized layer was prevented by the presence of tritium in water. Tritium durability tests were also carried out for the electrolysis cell of the chemical exchange column.
Nakamura, Hirofumi; Hatano, Yuji*; Yamanishi, Toshihiko
Fusion Engineering and Design, 87(5-6), p.916 - 920, 2012/08
Times Cited Count：4 Percentile：31.96(Nuclear Science & Technology)Deuterium behavior in the metal exposed to hot heavy water has been investigated in order to understand the oxidation driven tritium permeation in the fusion reactor. Disks of SS304, F82H and Ni and gold plated SS304 and F82H were oxidized in an autoclave at 573K. After the oxidation, soaked deuterium in the specimen was measured by the thermal desorption method and elemental depth distribution in the specimen was measured by a glow discharge optical elemental spectroscopy method. Obtained results were followings, (1) The oxide thickness has grown with the soaking time, and solved deuterium amount also increases with oxidation time for all materials. (2) Deuterium exists at the interface of the oxide and metal for all materials. (3) Deuterium in the gold plated samples were less than that in the bare SS304 about 1/5. (4) Deuterium in nickel was less than that in the SS304 by one orders magnitude and oxide thickness was also thinner than SS304. Those results indicate that deuterium solution into the material would be initiated by the deuterium gas production at the oxidation process of metal. Gold plating as the oxidation protection could be effective to prevent deuterium solution into the metal.
Hayashi, Takumi; Nakamura, Hirofumi; Isobe, Kanetsugu; Kobayashi, Kazuhiro; Oyaizu, Makoto; Yamanishi, Toshihiko; Oya, Yasuhisa*; Okuno, Kenji*
Fusion Engineering and Design, 87(7-8), p.1333 - 1337, 2012/08
Times Cited Count：8 Percentile：52.49(Nuclear Science & Technology)In order to investigate the behavior of hydrogen isotope on the water-metal boundary, deuterium permeation experiments from heavy water vessel through various metal piping, such as pure iron (Fe), nickel (Ni), stainless steel (SS304), and pure iron with 10 
m gold plating, were performed at 573 K and at 15 MPa. During the experiment, surfaces of metal piping except gold plating one were oxidized at the heavy water boundary and then deuterium would generate by the oxidation reactions. This deuterium could be detected by mass spectrometer, which monitored the inside gases of the piping under vacuum. The result showed clearly that the deuterium permeated through Fe, Ni, and SS304 piping was detected as deuterium gas (D) under vacuum, though that through gold plating one could not be detected effectively. The D permeation rate through Fe, Ni, and SS304 piping reached some stabilized value. This paper summarizes the above experimental results and discusses the mechanism of deuterium behavior on the water metal boundary.
Kobayashi, Kazuhiro; Nakamura, Hirofumi; Hayashi, Takumi; Yamanishi, Toshihiko
Fusion Science and Technology, 60(4), p.1335 - 1338, 2011/11
Times Cited Count：1 Percentile：10.73(Nuclear Science & Technology)In a fusion reactor of high safety and acceptability, safety confinement of tritium is one of key issues for the fusion reactor. Tritium should be well-controlled and not excessively released to environment and to prevent workers from excess exposure. Especially, the hot cell and tritium facility of ITER will be used various construction materials such as the concrete and the organic materials. Transport properties of tritiated water vapor (HTO) in the epoxy paint has been evaluated by the HTO exposure and removal behavior from the epoxy paint in order to obtain the data base of tritium behavior in the confinement facilities such as the hot cell or the tritium plant building of ITER.
Isobe, Kanetsugu; Nakamura, Hirofumi; Nakamichi, Masaru; Yamanishi, Toshihiko
Fusion Science and Technology, 60(4), p.1584 - 1587, 2011/11
Times Cited Count：3 Percentile：26.02(Nuclear Science & Technology)We focused on the reaction between tritium and carbon dioxide at elevated temperature, self-radiation reactions at 373, 473 and 573 K were investigated. Self-radiation experiment using high purity gaseous tritium was carried out in the chamber of stainless steel at atmospheric pressure and initial ratio between gaseous tritium and carbon dioxide was almost 1:1. After 2 weeks experiment, gas contents and these concentrations were measured with quadrupole mass spectrometer. Main products were carbon monoxide, water and methane. And production ratios of such products were almost same at any temperature. Therefore, it was found that self-radiation reaction between gaseous tritium and carbon dioxide is independent of temperature in the rage of 373-573 K.
Yamanishi, Toshihiko; Yamada, Masayuki; Suzuki, Takumi; Kawamura, Yoshinori; Nakamura, Hirofumi; Iwai, Yasunori; Kobayashi, Kazuhiro; Isobe, Kanetsugu; Inomiya, Hiroshi; Hayashi, Takumi
Fusion Science and Technology, 60(3), p.1083 - 1087, 2011/10
Times Cited Count：2 Percentile：18.29(Nuclear Science & Technology)Tritium Process Laboratory (TPL) in Japan Atomic Energy Agency has been established as the only test facilities to handle over 1 gram of in Japan. From March 1988, TPL has been operated with tritium, and no tritium release accident has been observed. The average tritium concentration in a stream from a stack of the TPL to environment was 71 Bq/m
, and was 1/70 of the Japanese regulation value for HTO. The failure data have been analyzed for several main components of the safety systems such as pumps, valves, and monitors. The data on the tritium waste and accountancy has also been accumulated. As a study of the Grants-in-Aid for Scientific Research, these data are analysed and are reported.
Nakamura, Hirofumi; Nakamichi, Masaru; Tanigawa, Hiroyasu; Yamanishi, Toshihiko
Journal of Nuclear Materials, 417(1-3), p.1150 - 1153, 2011/10
Times Cited Count：3 Percentile：26.02(Materials Science, Multidisciplinary)Deuterium permeation characteristics through various surface states ofF82H such as F82H without surface treatment (bare F82H), welded F82H,and gold plated F82H (Au-F82H) have been investigated in order to understand the effect of surface state on permeation for the realistic tritium permeation evaluation in the fusion reactors especially breeding blanket system, which has many welding points and permeation reduction coatings. Based on obtained permeation behavior, the steady state permeation and the diffusivity derived form the transient permeation behavior have been discussed. As the results, deuterium permeation through bare F82H is smaller than that through clean surface F82H. Asto the effect of welding on permeation, the results indicate that significant difference of welding is not observed between bare F82H and welded F82H. Finally, gold plating on F82H showed good permeation reduction performance.
Oyaizu, Makoto; Isobe, Kanetsugu; Nakamura, Hirofumi; Hayashi, Takumi; Yamanishi, Toshihiko
Journal of Nuclear Materials, 417(1-3), p.1143 - 1146, 2011/10
Times Cited Count：7 Percentile：48.91(Materials Science, Multidisciplinary)The tritium permeation behavior through F82H steel from carrier-free tritiated water vapor was investigated and the difference between as-received sample surface and that after the permeation experiments were analyzed by means of SEM, EDX and XRD. As the results, the permeability of tritium through F82H steel from tritiated water vapor is two to three orders of magnitude smaller than that from gaseous hydrogen. A thick and porous iron oxide layer composed of hematite and magnetite was formed in the permeation experiments. These results indicate that the oxide layer would hardly work as tritium permeation barrier, and that gaseous hydrogen could be generated by the redox reaction of water on the sample surface. Therefore, it could be considered that the tritium permeation through F82H steel from tritiated water vapor could result from the partial pressure of T.
Hayashi, Takumi; Nakamura, Hirofumi; Isobe, Kanetsugu; Kobayashi, Kazuhiro; Oyaizu, Makoto; Oya, Yasuhisa*; Okuno, Kenji*; Yamanishi, Toshihiko
Fusion Science and Technology, 60(1), p.369 - 372, 2011/07
Times Cited Count：2 Percentile：18.29(Nuclear Science & Technology)Nakamura, Hirofumi; Isobe, Kanetsugu; Nakamichi, Masaru; Yamanishi, Toshihiko
Fusion Engineering and Design, 85(7-9), p.1531 - 1536, 2010/12
Times Cited Count：17 Percentile：74.1(Nuclear Science & Technology)Tritium permeation reduction performance of various coatings was evaluated by means of deuterium permeation experiment and thermal stress analysis. Several coatings such as amorphous CrPO
, plasma sprayed zirconia (ZrO) and gold plating. As the results, ZrO showed relatively good permeation reduction performance about 1/10, and deuterium seems permeate through the grain boundaries or cracks of the ZrO. Improvement such as filling the diffusion path will be effective for further permeation reduction performance. On the other hand, gold plating showed excellent permeation reduction performance around 550 K. Permeation reduction by gold plating would be attributed to low solubility of deuterium in gold. Results of thermal stress analysis were consistent with the results of permeation experiment. Therefore, thermal stress analysis could be an effective method for the selecting permeation reduction coatings prior to the permeation experiment.
Yamanishi, Toshihiko; Hayashi, Takumi; Kawamura, Yoshinori; Nakamura, Hirofumi; Iwai, Yasunori; Kobayashi, Kazuhiro; Isobe, Kanetsugu; Suzuki, Takumi; Yamada, Masayuki
Fusion Engineering and Design, 85(7-9), p.1002 - 1006, 2010/12
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)The R&D for tritium technologies to a demonstration reactor (DEMO) is planned to be carried out in the Broader Approach (BA) program in Japan by JAEA with Japanese universities: (1) tritium analysis technology; (2) basic tritium safety research; and (3) tritium durability test. A multi-purpose RI facility is under construction at Rokkasho in Aomori to carry out the above R&D subjects. A preliminary safety study has been carried out for the amount of tritium released to the environment and for the radiation dose of workers. The main subjects of the R&D of tritium analysis are the technologies for real-time analysis for hydrogen isotopes, gas, liquid and solid. The materials of interest include F82H, SiC, ZrCo, solid and liquid advanced breeder and multipliers. In the tritium durability tests, organic materials and metals are studied for the radiation and the corrosion damage. A series of preliminary studies for the above subjects has been started.
Hayashi, Takumi; Iwai, Yasunori; Kobayashi, Kazuhiro; Nakamura, Hirofumi; Yamanishi, Toshihiko; Perevezentsev, A.*
Fusion Engineering and Design, 85(7-9), p.1386 - 1390, 2010/12
Times Cited Count：11 Percentile：59.22(Nuclear Science & Technology)In order to establish effective ITER atmosphere detritiation system (DS), JAEA has investigated the performance and the durability at various incident/accident conditions, and supported to finalize the DS conceptual design through the ITER design review. The current DS at the safety important component has been discussed and mainly consists of catalytic reactors, wet scrubber column (SC) and blowers. The functional failure of the DS design with SC was evaluated using database of failure experiences of valves, controllers and components. Even in the tritium release into the biggest confinement sector of Tokamak gallery, it improved more than tow orders of magnitude comparing with that of original DS design using Molecular Sieve (MS) dryer beds in the 2001 design report. This improvement is achieved mainly by the minimization of valve operation like MS dryers and by the standardized module arrangement of DS with SC.
Tobita, Kenji; Nishio, Satoshi*; Enoeda, Mikio; Nakamura, Hirofumi; Hayashi, Takumi; Asakura, Nobuyuki; Uto, Hiroyasu; Tanigawa, Hiroyasu; Nishitani, Takeo; Isono, Takaaki; et al.
JAEA-Research 2010-019, 194 Pages, 2010/08
JAEA-Research-2010-019-01.pdf:48.47MBJAEA-Research-2010-019-02.pdf:19.4MB
This report describes the results of the conceptual design study of the SlimCS fusion DEMO reactor aiming at demonstrating fusion power production in a plant scale and allowing to assess the economic prospects of a fusion power plant. The design study has focused on a compact and low aspect ratio tokamak reactor concept with a reduced-sized central solenoid, which is novel compared with previous tokamak reactor concept such as SSTR (Steady State Tokamak Reactor). The reactor has the main parameters of a major radius of 5.5 m, aspect ratio of 2.6, elongation of 2.0, normalized beta of 4.3, fusion out put of 2.95 GW and average neutron wall load of 3 MW/m
. This report covers various aspects of design study including systemic design, physics design, torus configuration, blanket, superconducting magnet, maintenance and building, which were carried out increase the engineering feasibility of the concept.
Nakamura, Hirofumi; Kobayashi, Kazuhiro; Yokoyama, Sumi*; Saito, Shigeru; Yamanishi, Toshihiko; Kikuchi, Kenji*
Journal of Plasma and Fusion Research SERIES, Vol.9, p.326 - 331, 2010/08
Based on results of tritium measurement in the SS316 specimens irradiated up to 5.9 dpa in the SINQ target (580 MeV proton) using a thermal desorption (TDS) method, trap site density and trap energy in the materials induced by the high-energy proton irradiation have been evaluated by means of the numerical tritium transport analysis. The results indicate that almost residual tritium in the SS316 specimen exists in the trap site, whose trap density is maximum 238 appm (5.9 dpa) and trap energy is 
1.4 eV, and that tritium release by the TDS is mainly attributed to the disappearance of the trap sites by the specimen heating, whose activation energy is about 0.7 eV. The trap site density seems to be almost proportional to the irradiation dose (dpa). Additionally, irradiation conditions such as the dose or irradiation temperature do not affect on the trapping mechanism.
Sakanaka, Shogo*; Akemoto, Mitsuo*; Aoto, Tomohiro*; Arakawa, Dai*; Asaoka, Seiji*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; et al.
Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2338 - 2340, 2010/05
Future synchrotron light source using a 5-GeV energy recovery linac (ERL) is under proposal by our Japanese collaboration team, and we are conducting R&D efforts for that. We are developing high-brightness DC photocathode guns, two types of cryomodules for both injector and main superconducting (SC) linacs, and 1.3 GHz high CW-power RF sources. We are also constructing the Compact ERL (cERL) for demonstrating the recirculation of low-emittance, high-current beams using above-mentioned critical technologies.
