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Journal Articles

Development of boron sheet and DT neutron irradiation experiments of multi-layered concrete structure with boron sheet

Sato, Satoshi; Maegawa, Toshio*; Yoshimatsu, Kenji*; Sato, Koichi*; Nonaka, Akira*; Takakura, Kosuke; Ochiai, Kentaro; Konno, Chikara

Progress in Nuclear Science and Technology (Internet), 4, p.623 - 626, 2014/04

In the previous study, we developed a multi-layered concrete structure to reduce induced activity in concrete applied for neutron generation facilities such as a fusion reactor. This structure is composed of low activation concrete as the first layer, boron doped low activation concrete as the second layer and ordinary concrete as the third layer from the side of the neutron source. In this study, as an alternative of the boron doped low activation concrete we have developed the boron doped resin sheet with boron carbonate and resin to reduce the construction cost. The weight ratio of the boron carbonate to the resin is 0.75. The developed boron sheet has good flexibility and sufficient strength for repeated bending. DT neutron irradiation experiments for four multi-layered concrete structures with the boron sheet have been performed at the FNS (Fusion Neutronics Source) facility in JAEA in order to study shielding performance of the structures with the boron sheet. Structure-1 of about 30 cm in width, 30 cm in height and 50 cm in thickness is composed of low activation concrete of 20 cm in thickness as the first layer and ordinary concrete of 30 cm in thickness as the second layer. The boron sheet is inserted between the first and second layers. In Structure-2 one more boron sheet is inserted at the 10 cm depth from the surface of Structure-1. Structure-3 added one more boron sheet at 30 cm depth from the surface of Strucure-2. For comparison, Structure-4 has no boron sheet. The reaction rates were measured every 5 cm in depth with activation foils of gold and niobium. By inserting the boron sheet, the reaction rate of the gold generated by low energy neutrons decreases by a factor of about four. It is demonstrated that the multi-layered concrete structure with the boron sheet effectively reduces low energy neutrons.

Journal Articles

Development of the water cooled ceramic breeder test blanket module in Japan

Enoeda, Mikio; Tanigawa, Hisashi; Hirose, Takanori; Suzuki, Satoshi; Ochiai, Kentaro; Konno, Chikara; Kawamura, Yoshinori; Yamanishi, Toshihiko; Hoshino, Tsuyoshi; Nakamichi, Masaru; et al.

Fusion Engineering and Design, 87(7-8), p.1363 - 1369, 2012/08

 Times Cited Count:33 Percentile:93.74(Nuclear Science & Technology)

The development of a Water Cooled Ceramic Breeder (WCCB) Test Blanket Module (TBM) is being performed as one of the most important steps toward DEMO blanket in Japan. For the TBM testing and evaluation toward DEMO blanket, the module fabrication technology development by a candidate structural material, reduced activation martensitic/ferritic steel, F82H, is one of the most critical items from the viewpoint of realization of TBM testing in ITER. Fabrication of a real scale first wall, side walls, a breeder pebble bed box and assembling of the first wall and side walls have succeeded. Recently, the real scale partial mockup of the back wall was fabricated. The fabrication procedure of the back wall, whose thickness is up to 90 mm, was confirmed toward the fabrication of the real scale back wall by F82H. This paper overviews the recent achievements of the development of the WCCB TBM in Japan.

Journal Articles

Development of a low activation concrete shielding wall by multi-layered structure for a fusion reactor

Sato, Satoshi; Maegawa, Toshio*; Yoshimatsu, Kenji*; Sato, Koichi*; Nonaka, Akira*; Takakura, Kosuke; Ochiai, Kentaro; Konno, Chikara

Journal of Nuclear Materials, 417(1-3), p.1131 - 1134, 2011/10

 Times Cited Count:7 Percentile:53.57(Materials Science, Multidisciplinary)

The multi-layered concrete structure has been developed to reduce induced activity in the concrete applied for neutron generation facilities such as a fusion reactor. The multi-layered concrete structure is composed of the low activation concrete as the first layer, the boron-doped low activation concrete as the second layer and the ordinary concrete as the third layer from the side of the neutron source. By applying the multi-layered concrete structure, the volume of the boron can drastically decrease compared with the monolithic boron-doped concrete. A 14 MeV neutron irradiation experiment with the multi-layered concrete structure mockups was performed at FNS and several reaction rates and induced activities in the mockups were measured. This experiment demonstrated that the multi-layered concrete effectively reduced low energy neutrons and induced activities.

Journal Articles

X-ray photon correlation spectroscopy study in valence fluctuation compound Eu$$_{3}$$S$$_{4}$$

Nakao, Hironori*; Owada, Kenji; Shimomura, Susumu*; Ochiai, Akira*; Namikawa, Kazumichi*; Mizuki, Junichiro; Mimura, Hidekazu*; Yamauchi, Kazuto*; Murakami, Yoichi*

AIP Conference Proceedings 1234, p.935 - 938, 2010/06

 Times Cited Count:2 Percentile:69.52

Journal Articles

Bulk 5$$f$$ electronic states of the uranium monochalcogenide US as seen via soft X-ray photoemission

Takeda, Yukiharu; Okane, Tetsuo; Okochi, Takuo*; Saito, Yuji; Yamagami, Hiroshi; Fujimori, Atsushi*; Ochiai, Akira*

Physical Review B, 80(16), p.161101_1 - 161101_4, 2009/10

 Times Cited Count:7 Percentile:35.36(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Structural phase transition in the spin gap system YbAl$$_3$$C$$_3$$

Matsumura, Takeshi*; Inami, Toshiya; Kosaka, Masashi*; Kato, Yoshiaki*; Inukai, Takaki*; Ochiai, Akira*; Nakao, Hironori*; Murakami, Yoichi*; Katano, Susumu*; Suzuki, Hiroyuki*

Journal of the Physical Society of Japan, 77(10), p.103601_1 - 103601_4, 2008/10

 Times Cited Count:12 Percentile:59.32(Physics, Multidisciplinary)

Journal Articles

Soft X-ray magnetic circular dichroism study of uranium monochalcogenides at uranium $$N_{4,5}$$ absorption edges

Okane, Tetsuo; Takeda, Yukiharu; Okamoto, Jun*; Mamiya, Kazutoshi*; Okochi, Takuo; Fujimori, Shinichi; Saito, Yuji; Yamagami, Hiroshi; Fujimori, Atsushi; Ochiai, Akira*; et al.

Journal of the Physical Society of Japan, 77(2), p.024706_1 - 024706_6, 2008/02

 Times Cited Count:13 Percentile:62.96(Physics, Multidisciplinary)

Journal Articles

Application of $$gamma$$ rays from D($$alpha$$,$$gamma$$)$$^{6}$$Li and $$^{19}$$F($$alpha$$,n)$$^{22}$$Na to alpha particle diagnostics

Ochiai, Kentaro; Kubota, Naoyoshi; Taniike, Akira*; Kitamura, Akira*; Kondo, Keitaro*; Nishitani, Takeo

Fusion Science and Technology, 51(2T), p.262 - 264, 2007/02

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

For the density of 3.5-MeV $$alpha$$ particle and the leakage $$alpha$$ particle in D-T plasmas, we propose the observation of 2.186-MeV $$gamma$$-ray produced by D($$alpha$$,$$gamma$$)$$^{6}$$Li reaction and the use of the activation method by $$^{19}$$F($$alpha$$,n)$$^{22}$$Na reaction, respectively. In order to verify these reaction rates, we have carried out the irradiation experiments by means of helium ion bombardment into a deuteride polyethylene and a calcium floride crystal samples. From our experiment, D($$alpha$$,$$gamma$$)$$^{6}$$Li reaction rate is estimated to be 10$$^{13}$$m$$^{-3}$$s$$^{-1}$$in the ITER typical plasma condition. So we obtained good prospect of the $$gamma$$-ray measurement as the confined $$alpha$$ diagnostics by using high efficiency detector. Also, it was found that The number of leakage alpha particles in order of 10$$^{18}$$m$$^{2}$$ could be estimated by the activation method with $$^{19}$$F($$alpha$$,n)$$^{22}$$Na.

Journal Articles

Soft X-ray magnetic circular dichroism study of ferromagnetic uranium compounds

Okane, Tetsuo; Takeda, Yukiharu; Fujimori, Shinichi; Saito, Yuji; Okamoto, Jun*; Mamiya, Kazutoshi*; Muramatsu, Yasuji*; Fujimori, Atsushi; Ochiai, Akira*; Haga, Yoshinori; et al.

Journal of the Physical Society of Japan, 75(Suppl.), p.105 - 106, 2006/08

no abstracts in English

JAEA Reports

Quantitative analysis on the surface of Lithium-6 enriched lithium titanate using proton RBS (Cooperative research)

Kubota, Naoyoshi; Fujiwara, Yoshio*; Okumura, Kazutaka*; Ochiai, Kentaro; Kitamura, Akira*; Furuyama, Yuichi*; Taniike, Akira*; Nishitani, Takeo

JAEA-Research 2006-019, 15 Pages, 2006/06

JAEA-Research-2006-019.pdf:0.75MB

Surface analysis of lithium-6 ($$^{6}$$Li) was performed for both 95 % and 40 % $$^{6}$$Li-enriched lithium titanate (Li$$_{2}$$TiO$$_{3}$$) samples as the candidate tritium breeding material using 2.6 MeV-proton Rutherford Backscattering Spectroscopy (RBS). The depth resolution of this method was enough to measure the $$^{6}$$Li depth profile in terms of the evaluation of thermal neutron transportation. The atomic density of $$^{6}$$Li could be measured within the error of 27 % for both samples although the accuracy of 5 % was not achieved for the evaluation of tritium breeding. It was confirmed that the sample atomic compositions agreed with Li$$_{2}$$TiO$$_{3}$$ within errors of 30 % for Li/Ti and 15 % for O/Ti. The whole errors were caused by the data accuracy of scattering cross sections predominately. Providing more accurate cross section data can lead to the utilization of the RBS method for tritium breeding materials analysis.

Journal Articles

Irradiation and penetration tests of boron-doped low activation concrete using 2.45 MeV and 14 MeV neutron sources

Morioka, Atsuhiko; Sato, Satoshi; Kinno, Masaharu*; Sakasai, Akira; Hori, Junichi*; Ochiai, Kentaro; Yamauchi, Michinori*; Nishitani, Takeo; Kaminaga, Atsushi; Masaki, Kei; et al.

Journal of Nuclear Materials, 329-333(2), p.1619 - 1623, 2004/08

 Times Cited Count:7 Percentile:46.83(Materials Science, Multidisciplinary)

The neutron penetration and the activation characteristics of the boron-doped low activation concrete were investigated for irradiation of 2.45 and 14 MeV neutrons. The shielding property of the 2 wt% boron-doped low activation concrete is superior to that of the 1 wt% boron for the thermal neutron, on the contrary to the no clear difference for the fast neutron. The total activity detected in the boron-doped low activation concrete was about one hundredth of that in the geostandard sample at more than 30 days cooling time. The total activity of the boron-doped concrete by major nuclei does not depend on the boron density for the 14 MeV neutron irradiation.

Journal Articles

Neutron transmission experiment of boron-doped resin for the JT-60SC neutron shield using 2.45 MeV neutron source

Morioka, Atsuhiko; Sato, Satoshi; Ochiai, Kentaro; Sakasai, Akira; Hori, Junichi; Yamauchi, Michinori*; Nishitani, Takeo; Kaminaga, Atsushi; Masaki, Kei; Sakurai, Shinji; et al.

Journal of Nuclear Science and Technology, 41(Suppl.4), p.109 - 112, 2004/03

Neutron shielding material of the port section of JT-60 superconducting modification (JT-60SC) serves as a design which used resin (KRAFTON-HB4) excellent in the temperature characteristic from polyethylene. In order to make port weight mitigate and reduce the nuclear heating of the superconducting coil, we were developed the resin which added natural BORON to resin. The 2.45MeV neutron generated in the D-D reaction was irradiated, the penetration of the neutron was measured in some kinds of samples which changed the amount of BORON, and the shielding performance of the resin containing BORON was compared with them. The penetration rates of fast neutron flux do not depend on the doped density of boron in both measurements. Whereas the penetration rates of thermal neutron flux in the resin with 2 wt% B are about 25% lower than those with 1 wt% at the back surface of the test specimens.

Journal Articles

X-ray magnetic circular dichroism at the U $$N_{4,5}$$ edges of uranium monochalcogenides US, USe and UTe

Okane, Tetsuo; Okamoto, Jun; Mamiya, Kazutoshi; Fujimori, Shinichi; Saito, Yuji; Muramatsu, Yasuji; Fujimori, Atsushi; Ochiai, Akira*

Physica B; Condensed Matter, 345(1-4), p.221 - 224, 2004/03

 Times Cited Count:4 Percentile:26.12(Physics, Condensed Matter)

Magnetic circular dichroism (MCD) has been measured at the U $$N_{4,5}$$ absorption edges of ferromagnetic uranium monochalcogenides US, USe and UTe. The MCD signals are weaker in US than in USe and UTe. Both the spin and orbital moments are increased in going from US to USe, and then reduced from USe to UTe.

Journal Articles

High-resolution resonance photoemission study of Ce$$MX$$ ($$M$$=Pt, Pd; $$X$$=P, As, Sb)

Iwasaki, T.*; Sekiyama, Akira*; Yamasaki, Atsushi*; Okazaki, Makoto*; Kadono, Koji*; Utsunomiya, Hiroshi*; Imada, Shin*; Saito, Yuji; Muro, Takayuki*; Matsushita, Tomohiro*; et al.

Physical Review B, 65(19), p.195109_1 - 195109_9, 2002/05

 Times Cited Count:23 Percentile:72.01(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Development of Quadrupole Type Mass Spectrometer for Analysis of UF$$_{6}$$

Nagatoro, Yuko*; Suzuki, Shohachi*; Ochiai, Kenichi; Kaya, Akira*

Shitsuryo Bunseki, 26(4), p.321 - 332, 1978/12

Oral presentation

Measurement of $$gamma$$-ray by $$^{4}$$He(d,$$gamma$$)reaction and its application for burning plasma diagnostics

Kubota, Naoyoshi; Ochiai, Kentaro; Taniike, Akira*; Kitamura, Akira*

no journal, , 

no abstracts in English

Oral presentation

Measurement of Li isotope distribution in Li$$_2$$TiO$$_3$$ for blanket materials of fusion reactor using nuclear reaction analysis

Takahashi, Genki*; Furuyama, Yuichi*; Okamoto, Masanori*; Kawatsu, Sho*; Taniike, Akira*; Kitamura, Akira*; Kubota, Naoyoshi; Ochiai, Kentaro; Nishitani, Takeo

no journal, , 

no abstracts in English

Oral presentation

The Annihilation behavior of irradiation defects induced by 14 MeV and thermal neutron irradiation in Li$$_{4}$$SiO$$_{4}$$

Nishikawa, Yusuke*; Oyaizu, Makoto*; Suda, Taichi*; Yoshikawa, Akira*; Shinozaki, Takashi*; Munakata, Kenzo*; Fujii, Toshiyuki*; Yamana, Hajimu*; Takakura, Kosuke; Ochiai, Kentaro; et al.

no journal, , 

no abstracts in English

Oral presentation

Composition analysis of Li compounds for blanket candidate materials with accelerator analysis

Takahashi, Genki*; Kawatsu, Sho*; Unehara, Hiroshi*; Furuyama, Yuichi*; Taniike, Akira*; Kitamura, Akira*; Ochiai, Kentaro; Kubota, Naoyoshi; Nishitani, Takeo

no journal, , 

no abstracts in English

Oral presentation

Soft X-ray magnetic circular dichroism study of ferromagnetic uranium monochalcogenides

Okane, Tetsuo; Takeda, Yukiharu; Okamoto, Jun*; Mamiya, Kazutoshi*; Fujimori, Shinichi; Saito, Yuji; Yamagami, Hiroshi; Fujimori, Atsushi; Ochiai, Akira*; Tanaka, Arata*

no journal, , 

no abstracts in English

25 (Records 1-20 displayed on this page)