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Tokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Haga, Yoshinori; Tokiwa, Yoshifumi; Opletal, P.; Fujibayashi, Hiroyuki*; Kinjo, Katsuki*; Kitagawa, Shunsaku*; Ishida, Kenji*; et al.
Journal of the Physical Society of Japan, 91(2), p.023707_1 - 023707_5, 2022/02
Te NMR experiments in field (
) applied along the easy magnetization axis (the 
-axis) revealed slow electronic dynamics developing in the paramagnetic state of UTe. The observed slow fluctuations are concerned with a successive growth of long-range electronic correlations below 30
40 K, where the spin susceptibility along the hard magnetization axis (the 
-axis) shows a broad maximum. The experiments also imply that tiny amounts of disorder or defects locally disturb the long-range electronic correlations and develop an inhomogeneous electronic state at low temperatures, leading to a low temperature upturn observed in the bulk-susceptibility in 
. We suggest that UTe would be located on the paramagnetic side near an electronic phase boundary, where either the magnetic or Fermi-surface instability would be the origin of the characteristic fluctuations.
Ono, Masato; Shimizu, Atsushi; Ohashi, Hirofumi; Hamamoto, Shimpei; Inoi, Hiroyuki; Tokuhara, Kazumi*; Nomoto, Yasunobu*; Shimazaki, Yosuke; Iigaki, Kazuhiko; Shinozaki, Masayuki
Nuclear Engineering and Design, 386, p.111585_1 - 111585_9, 2022/01
In the late 1980s during the design stage, the seismic classification of the high temperature engineering test reactor (HTTR) was formulated. Owing to the lack of operation experiences of the HTTR to sufficiently understand the safety characteristics of high temperature gas cooled reactors (HTGR) at that time, the seismic classification of commercial light water reactors (LWR) was applied to HTTR. However, the subsequent operation experiences and test results using HTTR made it clear that the seismic classification of commercial LWR was somewhat too conservative for the HTGR. As a result, Class S facilities were downgraded compared to the commercial LWR. Moreover, the validity of the new seismic classification is confirmed. In June 2020, the Nuclear Regulatory Authority approved that the result of the seismic classification conformed to the standard rules of the reactor installation change.
Te-NMR study on a single crystal of heavy fermion superconductor UTeTokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Hattori, Taisuke; Higa, Nonoka; Nakamine, Genki*; Kitagawa, Shunsaku*; Ishida, Kenji*; Nakamura, Ai*; Shimizu, Yusei*; et al.
Journal of the Physical Society of Japan, 88(7), p.073701_1 - 073701_4, 2019/07
Times Cited Count：29 Percentile：95.25(Physics, Multidisciplinary)We report Te-NMR studies on a newly discovered heavy fermion superconductor UTe. Using a single crystal, we have measured the Te-NMR Knight shift 
and spin-lattice relaxation rate 
for fields along the three orthorhombic crystal axes. The data confirm a moderate Ising anisotropy for both the static () and dynamical susceptibilities () in the paramagnetic state above about 20 K. Around 20 K, however, we have observed a sudden loss of NMR spin-echo signal due to sudden enhancement of the NMR spin-spin relaxation rate 
, when the field is applied along the easy axis of magnetization (= axis). This behavior suggests the development of longitudinal magnetic fluctuations along the axis at very low frequencies below 20 K.
Ir
Si
with one-dimensional uranium zigzag chainsLi, D. X.*; Honda, Fuminori*; Miyake, Atsushi*; Homma, Yoshiya*; Haga, Yoshinori; Nakamura, Ai*; Shimizu, Yusei*; Maurya, A.*; Sato, Yoshiki*; Tokunaga, Masashi*; et al.
Physical Review B, 99(5), p.054408_1 - 054408_9, 2019/02
Times Cited Count：2 Percentile：22.92(Materials Science, Multidisciplinary)
Pt NMRTokunaga, Yo; Nakamura, Ai*; Aoki, Dai*; Shimizu, Yusei*; Homma, Yoshiya*; Honda, Fuminori*; Sakai, Hironori; Hattori, Taisuke; Kambe, Shinsaku
Physical Review B, 98(1), p.014425_1 - 014425_5, 2018/07
Times Cited Count：1 Percentile：8.26(Materials Science, Multidisciplinary)Pt NMR measurements have been performed on a single crystal of the uranium-based compound UPtGe, which is the only 5f system known to possess an incommensurate helical (cycloidal) structure below TN = 50 K. Knight shift measurement confirmed the isotropic character of the static spin susceptibilities in hexagonal-like ac crystal planes of the EuAuGe-type crystal structure. The hyperfine coupling constants were also found to be isotropic in the planes. Nuclear relaxation rate measurement revealed the development of the antiferro-magnetic spin fluctuations with XY character confined to the hexagonal-like plane below 200 K. The results present a clear contrast to the Ising anisotropy of the fluctuations in ferromagnetic superconductors UCoGe and URhGe.
Umeda, Koji; Yasue, Kenichi; Kokubu, Yoko; Niwa, Masakazu; Asamori, Koichi; Fujita, Natsuko; Shimizu, Mayuko; Matsubara, Akihiro; Tamura, Hajimu; Yokoyama, Tatsunori; et al.
JAEA-Review 2015-019, 42 Pages, 2015/09
JAEA-Review-2015-019.pdf:4.64MB
This report is a plan of research and development (R&D) on geosphere stability for long-term isolation of high-level radioactive waste (HLW) in JAEA, in fiscal year 2015. The objectives and contents in fiscal year 2015 are described in detail based on the outline of 7 years plan (fiscal years 2015-2021). Background of this research is clarified with the necessity and the significance for site investigation and safety assessment, and the past progress in this report. In addition, the plan framework is structured into the following categories: (1) Development and systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques.
Umeda, Koji; Yasue, Kenichi; Kokubu, Yoko; Niwa, Masakazu; Asamori, Koichi; Fujita, Natsuko; Shimizu, Mayuko; Shimada, Akiomi; Matsubara, Akihiro; Tamura, Hajimu; et al.
JAEA-Review 2015-012, 43 Pages, 2015/08
JAEA-Review-2015-012.pdf:1.24MB
The concept of geological disposal of high-level radioactive waste (HLW) in Japan is based on a multibarrier system which combines a stable geological environment with an engineered barrier system. Potential geological host formations and their surroundings are chosen, in particular, for their long-term stability, taking into account the fact that Japan is located in tectonically active zone. This report is to outline 7 years plan (fiscal years 2015-2021) of research and development (R&D) for geosphere stability for long-term isolation of the HLW in JAEA. Background of this research is clarified with the necessity and the significance, and the past progress in this report. The objectives, outline, contents and schedule during the next 7 years are described in detail. In addition, the plan framework is structured into the following categories: (1) Development and Systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques.
Asakura, Nobuyuki; Hoshino, Kazuo; Shimizu, Katsuhiro; Shinya, Kichiro*; Uto, Hiroyasu; Tokunaga, Shinsuke; Tobita, Kenji; Ono, Noriyasu*
Journal of Nuclear Materials, 463, p.1238 - 1242, 2015/08
Times Cited Count：11 Percentile：76.52(Materials Science, Multidisciplinary)Arrangements of interlink divertor coils and divertor geometries for short super-X was proposed as the Demo advanced divertor design. Performance of plasma detachment under the large heat flux was investigated to optimize the divertor design, using SONIC simulation with Ar impurity seeding, where Pout = 500 MW, ne = 7
10
m
at the core-edge boundary and the same diffusion coefficients for ITER simulation. Effects on the plasma temperature and density distributions were compared to the conventional divertor. The first run results with the same radiation power fraction of 0.92 in the conventional divertor showed that full detached plasma is produced, the maximum radiation region was maintained upstream the divertor target, and both the plasma heat load plus radiation load at the target was reduced to 10 MWmm
level. Simulation for the lower radiation power fractions of 0.8-0.9 was also performed, and physics issues of the short super-X divertor are discussed.
-lactamase from the moderate halophile 
sp.560 and the discovery of a Cs
-selective binding siteArai, Shigeki; Yonezawa, Yasushi*; Okazaki, Nobuo*; Matsumoto, Fumiko*; Shibazaki, Chie; Shimizu, Rumi; Yamada, Mitsugu*; Adachi, Motoyasu; Tamada, Taro; Kawamoto, Masahide*; et al.
Acta Crystallographica Section D, 71(3), p.541 - 554, 2015/03
Times Cited Count：4 Percentile：40.84(Biochemical Research Methods)The crystal structure of halophilic -lactamase from sp.560 (HaBLA) was determined using X-ray crystallography. Moreover, the locations of bound Sr
and Cs ions were identified by anomalous X-ray diffraction. The location of one Cs specific binding site was identified on HaBLA even in the presence of 9-fold molar excess of Na (90 mM Na /10 mM Cs). This Cs binding site is formed by two main-chain O atoms and an aromatic ring of a side chain of Trp. An aromatic ring of Trp interacts with Cs by the cation-
interaction. The observation of a selective and high-affinity Cs binding site provides important information that is useful for designing artificial Cs binding sites useful in bioremediation of radioactive isotopes.
Hoshino, Kazuo; Asakura, Nobuyuki; Shimizu, Katsuhiro; Tokunaga, Shinsuke
Proceedings of 25th IAEA Fusion Energy Conference (FEC 2014) (CD-ROM), 6 Pages, 2014/10
Hoshino, Kazuo; Asakura, Nobuyuki; Shimizu, Katsuhiro; Tokunaga, Shinsuke; Takizuka, Tomonori*; Someya, Yoji; Nakamura, Makoto; Uto, Hiroyasu; Sakamoto, Yoshiteru; Tobita, Kenji
Plasma and Fusion Research (Internet), 9(Sp.2), p.3403070_1 - 3403070_8, 2014/06
no abstracts in English
Asakura, Nobuyuki; Shimizu, Katsuhiro; Hoshino, Kazuo; Tobita, Kenji; Tokunaga, Shinsuke; Takizuka, Tomonori*
Nuclear Fusion, 53(12), p.123013_1 - 123013_15, 2013/12
Times Cited Count：39 Percentile：90.68(Physics, Fluids & Plasmas)Power exhaust scenario for 3 GW fusion reactor has been developed with enhancing the radiation loss from seeding impurity. Impurity transport and plasma detachment were simulated self-consistently under the Demo divertor condition using an integrated divertor code SONIC. Power handling with different seeding impurities showed that the total heat load, including the plasma transport and radiation, was reduced from 15 MW/m
to 10 MW/m for the higher Z case, where both heat load components became comparable. Effects of a long-leg divertor were examined. Full detachment was obtained and peak heat load was decreased to 12 MW/m, where neutral load became comparable to the plasma and radiation load, which may be due to small flux expansion. Finally, plasma diffusion significantly affected the performance of the plasma detachment. Peak heat lard was reduced to 5 MW/m well below engineering design level, with uniformly increasing the diffusion coefficient by the factor of two.
Satoh, Daiki; Maeda, Yoshikazu*; Tameshige, Yuji*; Nakashima, Hiroshi; Shibata, Tokushi*; Endo, Akira; Tsuda, Shuichi; Sasaki, Makoto*; Maekawa, Motokazu*; Shimizu, Yasuhiro*; et al.
Journal of Nuclear Science and Technology, 49(11), p.1097 - 1109, 2012/11
Times Cited Count：10 Percentile：65.97(Nuclear Science & Technology)At the Fukui Prefectural Hospital Proton Therapy Center, neutron doses behind concrete shields and at maze have been measured by using radiation monitors, DARWIN, Wendi-2, a rem meter, and solid state nuclear track detectors. The measured data were compared with the estimations by analytical models and Monte Carlo code PHITS. The analytical model with the parameters employed in shielding design of the facility gave considerably larger estimates than the measured data. This means that the facility was designed with an enough safety margin. The calculation results of PHITS were less than those of the analytical model, and were about 3 times larger than the measured data. From the view point of a safety policy with conservative estimation for shielding design, Monte Carlo simulation is a better tool for estimating radiation safety at accelerator-based proton treatment facilities.
Ozeki, Takahisa; Hayashi, Nobuhiko; Honda, Mitsuru; Aiba, Nobuyuki; Hamamatsu, Kiyotaka; Shimizu, Katsuhiro; Kawashima, Hisato; Hoshino, Kazuo; Takizuka, Tomonori; Tokuda, Shinji
Journal of Plasma and Fusion Research SERIES, Vol.8, p.1138 - 1142, 2009/09
*; Futakawa, Masatoshi; Ioka, Ikuo; Onuki, Kaoru; Shimizu, Saburo; Eto, Motokuni; Oku, Tatsuo*; *
Zairyo, 48(7), p.746 - 752, 1999/07
no abstracts in English
ray detector system for radioactivity measurement in deep seaYamamoto, Tadatoshi; Shimizu, Toku; Kozawa, Teruo; Birumachi, Atsushi; ; Katagiri, Masaki
JAERI-Research 99-032, 59 Pages, 1999/04
JAERI-Research-99-032.pdf:6.47MB
no abstracts in English
Tokuda, Shinji; Takizuka, Tomonori; Kishimoto, Yasuaki; Yamagiwa, Mitsuru; Shimizu, Katsuhiro; Ishii, Yasutomo; Azumi, Masafumi; *
ANU-PRL-TP-96/01, 0, p.70 - 72, 1996/00
no abstracts in English
Ando, Toshiro; Takatsu, Hideyuki; Nakamura, Hiroo; Yamamoto, Masahiro; ; Arai, Takashi; Kaminaga, Atsushi; ; Horiike, Hiroshi; Shimizu, Masatsugu; et al.
Kaku Yugo Kenkyu, 65(SPECIAL ISSUE), p.27 - 49, 1991/03
no abstracts in English
Eto, Motokuni; Fukaya, Kiyoshi; Oku, Tatsuo*; *; ; Takatsu, Hideyuki; Ando, Toshiro; Yamamoto, Masahiro; ; Shimizu, Masatsugu
Int. Symp. on Carbon New Processing and New Applications; Extended Abstracts,Vol. l, p.206 - 209, 1990/11
no abstracts in English
Fujine, Sachio; Shimizu, Toku; Saito, Keiichiro; Shiba, Koreyuki
JAERI-M 89-176, 100 Pages, 1989/10
no abstracts in English
