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Watakabe, Tomoyoshi; Yamamoto, Tomohiko; Okamura, Shigeki; Miyazaki, Masashi; Miyagawa, Takayuki; Uchita, Masato*; Hirayama, Tomoyuki*; Somaki, Takahiro*; Yukawa, Masaki*; Fukasawa, Tsuyoshi*; et al.
Proceedings of ASME 2024 Pressure Vessels & Piping Conference (PVP 2024) (Internet), 10 Pages, 2024/07
To secure the seismic safety of the thin-walled mechanical components and piping under a severe design earthquake level, employing a three-dimensional (3D) seismic isolation system has been planned in a sodium-cooled fast reactor. The development results of the 3D isolation system have been reported in previous papers so far. Its update is reported in Part 7 to Part 9. Part 7 describes the overview of the development, the test plan of the isolation system in the assembled state of each element, and the performance of individual isolation elements. In part 8, the performance of the isolation device that each element was assembled into was investigated through loading tests. Part 9 reports analytical studies by an analysis model validated based on the insight of the test results.
Somaki, Takahiro*; Yukawa, Masaki*; Fukasawa, Tsuyoshi*; Hirayama, Tomoyuki*; Uchita, Masato*; Miyagawa, Takayuki; Okamura, Shigeki; Yamamoto, Tomohiko; Watakabe, Tomoyoshi; Miyazaki, Masashi; et al.
Proceedings of ASME 2024 Pressure Vessels & Piping Conference (PVP 2024) (Internet), 9 Pages, 2024/07
Fukasawa, Tsuyoshi*; Somaki, Takahiro*; Yukawa, Masaki*; Hirayama, Tomoyuki*; Watakabe, Tomoyoshi; Yamamoto, Tomohiko; Okamura, Shigeki; Miyazaki, Masashi; Uchita, Masato*; Miyagawa, Takayuki; et al.
Proceedings of ASME 2024 Pressure Vessels & Piping Conference (PVP 2024) (Internet), 10 Pages, 2024/07
Yamamoto, Tomohiko; Okamura, Shigeki; Hirayama, Tomoyuki*; Somaki, Takahiro*
Haikan Gijutsu, 65(13), p.1 - 4, 2023/11
The authors are conducting research and development on three-dimensional seismic isolation devices to improve the earthquake resistance of future sodium-cooled fast reactors. This paper introduces an overview of the device and how to use it.
Fukasawa, Tsuyoshi*; Yamamoto, Tomohiko; Uchita, Masato*; Hirayama, Tomoyuki*
Dai-10-Kai Kozobutsu No Anzensei, Shinraisei Ni Kansuru Kokunai Shimpojiumu (JCOSSAR2023) Koen Rombunshu (Internet), p.135 - 142, 2023/10
Horizontal seismic isolation systems have been studied for Sodium-Cooled Fast Reactors to improve their seismic resistance. However, challenges arise in reducing seismic forces not only in the horizontal direction but also in the vertical direction. The authors have developed a new three-dimensional seismic isolation system to address this issue. A 1/2-scale test specimen was fabricated, and the force-displacement relationships were examined using static loading tests with a maximum axial force of 8000 kN to evaluate the feasibility of this design. Moreover, a horizontal oil damper was fabricated as a horizontal damping element, and its damping force was assessed through excitation tests with a maximum velocity of 2.7 m/s. This paper reports the findings of these tests.
OKondo, Yosuke*; Achouri, N. L.*; Al Falou, H.*; Atar, L.*; Aumann, T.*; Baba, Hidetada*; Boretzky, K.*; Caesar, C.*; Calvet, D.*; Chae, H.*; et al.
Nature, 620(7976), p.965 - 970, 2023/08
Times Cited Count：32 Percentile：94.93(Multidisciplinary Sciences)no abstracts in English
Fukasawa, Tsuyoshi*; Hirayama, Tomoyuki*; Yokoi, Shinobu*; Hirota, Akihiko*; Somaki, Takahiro*; Yukawa, Masaki*; Miyagawa, Takayuki; Uchita, Masato*; Yamamoto, Tomohiko; Miyazaki, Masashi; et al.
Nihon Kikai Gakkai Rombunshu (Internet), 89(924), p.23-00023_1 - 23-00023_17, 2023/08
no abstracts in English
Ne at the transition into the island of inversion; Detailed structure study of NeWang, H.*; Yasuda, Masahiro*; Kondo, Yosuke*; Nakamura, Takashi*; Tostevin, J. A.*; Ogata, Kazuyuki*; Otsuka, Takaharu*; Poves, A.*; Shimizu, Noritaka*; Yoshida, Kazuki; et al.
Physics Letters B, 843, p.138038_1 - 138038_9, 2023/08
Times Cited Count：5 Percentile：69.17(Astronomy & Astrophysics)Detailed 
-ray spectroscopy of the exotic neon isotope Ne has been performed using the one-neutron removal reaction from Ne. Based on an analysis of parallel momentum distributions, a level scheme with spin-parity assignments has been constructed for Ne and the negative-parity states are identified for the first time. The measured partial cross sections and momentum distributions reveal a significant intruder p-wave strength providing evidence of the breakdown of the N = 20 and N = 28 shell gaps. Only a weak, possible f-wave strength was observed to bound final states. Large-scale shell-model calculations with different effective interactions do not reproduce the large p-wave and small f-wave strength observed experimentally, indicating an ongoing challenge for a complete theoretical description of the transition into the island of inversion along the Ne isotopic chain.
Takahashi, Tomoyuki*; Fukaya, Yukiko*; Iimoto, Takeshi*; Uni, Yasuo*; Kato, Tomoko; Sun, S.*; Takeda, Seiji; Nakai, Kunihiro*; Nakabayashi, Ryo*; Uchida, Shigeo*; et al.
Hoken Butsuri (Internet), 56(4), p.288 - 305, 2021/12
We report the results of activities related to the Task Group of Parameters Used in Biospheric Dose Assessment Models for Radioactive Waste Disposal at the Japan Health Physics Society.
Wang, H.*; Otsu, Hideaki*; Chiga, Nobuyuki*; Kawase, Shoichiro*; Takeuchi, Satoshi*; Sumikama, Toshiyuki*; Koyama, Shumpei*; Sakurai, Hiroyoshi*; Watanabe, Yukinobu*; Nakayama, Shinsuke; et al.
Communications Physics (Internet), 2(1), p.78_1 - 78_6, 2019/07
Times Cited Count：10 Percentile：55.63(Physics, Multidisciplinary)Searching for effective pathways for the production of proton- and neutron-rich isotopes through an optimal combination of reaction mechanism and energy is one of the main driving forces behind experimental and theoretical nuclear reaction studies as well as for practical applications in nuclear transmutation of radioactive waste. We report on a study on incomplete fusion induced by deuteron, which contains one proton and one neutron with a weak binding energy and is easily broken up. This reaction study was achieved by measuring directly the cross sections for both proton and deuteron for 
Pd at 50 MeV/u via inverse kinematics technique. The results provide direct experimental evidence for the onset of a cross-section enhancement at high energy, indicating the potential of incomplete fusion induced by loosely-bound nuclei for creating proton-rich isotopes and nuclear transmutation of radioactive waste.
Morobishi, Ryota*; Yukawa, Masaki*; Hirayama, Tomoyuki*; Miyagawa, Takayuki*; Yamamoto, Tomohiko; Miyazaki, Masashi; Fukasawa, Tsuyoshi*
no journal, ,
no abstracts in English
Okamura, Shigeki; Hirayama, Tomoyuki*; Yokoi, Shinobu*; Morobishi, Ryota*; Yukawa, Masaki*; Yamamoto, Tomohiko; Uchita, Masato*; Fujita, Satoshi*
no journal, ,
no abstracts in English
Okamura, Shigeki; Nakashima, Risako*; Minami, Ayako*; Yokoi, Shinobu*; Hirayama, Tomoyuki*; Kotake, Shoji*; Fujita, Satoshi*; Yamaguchi, Akira*
no journal, ,
no abstracts in English
Yamamoto, Tomohiko; Hirayama, Tomoyuki*; Yokoi, Shinobu*; Morobishi, Ryota*; Yukawa, Masaki*; Okamura, Shigeki; Uchita, Masato*; Fujita, Satoshi*
no journal, ,
no abstracts in English
Hirayama, Tomoyuki*; Yokoi, Shinobu*; Uchita, Masato*; Yamamoto, Tomohiko; Okamura, Shigeki
no journal, ,
no abstracts in English
Yukawa, Masaki*; Morobishi, Ryota*; Yokoi, Shinobu*; Hirayama, Tomoyuki*; Yamamoto, Tomohiko; Okamura, Shigeki
no journal, ,
no abstracts in English
Futagami, Satoshi; Hayafune, Hiroki; Enuma, Yasuhiro*; Ogumo, Shinya*; Hirayama, Tomoyuki*; Murakami, Hisatomo*
no journal, ,
no abstracts in English
Yokoi, Shinobu*; Hirayama, Tomoyuki*; Yukawa, Masaki*; Morobishi, Ryota*; Yamamoto, Tomohiko; Okamura, Shigeki
no journal, ,
no abstracts in English
Ezato, Koichiro; Suzuki, Satoshi; Seki, Yohji; Mori, Kensuke; Hirayama, Tomoyuki; Kakudate, Satoshi
no journal, ,
no abstracts in English
Seki, Yohji; Ezato, Koichiro; Suzuki, Satoshi; Yokoyama, Kenji; Yamada, Hirokazu; Hirayama, Tomoyuki
no journal, ,
Through R&D for a plasma facing unit (PFU) of an ITER full-tungsten (W) divertor, Japan Atomic Energy Agency (JAEA) succeeded in demonstrating the durability of the cyclic heat loaded W divertor which was shaped by an electrical discharge machining (EDM). To prevent melting of W, an adequate technology to meet requirements of a geometrical shape and tolerance of the PFU is one of the most important key issues in a manufacturing process. JAEA has evaluated the EDM to control the final shape tolerance of 
0.25 mm. In order to examine an effect on durability of the micro-crack due to EDM, one polished W armor without the EDM and three W armors with the EDM were exposed to cyclic thermal loads. As the result, all of the W armors endured the repetitive heat load of 20 MW/m
1000 cycles without any macro-cracks, which strongly encourages the realization of the PFU of ITER full-W divertor with various geometrical shape and high accuracy tolerance.
