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Nagasumi, Satoru; Hasegawa, Toshinari; Nakagawa, Shigeaki; Kubo, Shinji; Iigaki, Kazuhiko; Shinohara, Masanori; Saikusa, Akio; Nojiri, Naoki; Saito, Kenji; Furusawa, Takayuki; et al.
JAEA-Research 2025-005, 23 Pages, 2025/07
JAEA-Research-2025-005.pdf:2.68MB
A safety demonstration test under abnormal operating conditions using the HTTR (High Temperature Engineering Test Reactor) was conducted to demonstrate safety features of the HTGRs (High Temperature Gas-cooled Reactors). Under a simulation of a control rod shutdown failure, all primary helium gas circulators were intentionally stopped during a steady-state operation at 100% reactor thermal power (30 MW), temporal changes of the reactor power and temperatures around the reactor pressure vessel (RPV) were obtained after the complete loss of forced heat removal from the reactor core. After the event (primary coolant flow stopped), the reactor power quickly decreased due to the negative reactivity feedback associated with the core temperature rise, and then the reactor power spontaneously shifted to a stable state of low power (about 1.2%) even after a recriticality. Heat dissipation from RPV surface to a surrounding vessel cooling system (water-cooled panels) ensured the amount of heat removal required to maintain the reactor temperature constant in the low power state. In this way, the transition from the event occurrence to the stable and safety state, i.e., inherent safety features of HTGRs, were demonstrated in the case of core forced cooling loss without active shutdown operations.
C and 500CTakagi, Honoka*; Yabutsuka, Takeshi*; Hayashida, Hirotoshi*; Song, F.; Kai, Tetsuya; Shinohara, Takenao; Kurita, Keisuke; Iikura, Hiroshi; Yamamoto, Norio*; Nakajima, Minoru*; et al.
Solid State Ionics, 417, p.116716_1 - 116716_7, 2024/12
Times Cited Count：3 Percentile：46.95(Chemistry, Physical)
-wave resonance of 
+
Okudaira, Takuya*; Nakabe, Rintaro*; Auton, C. J.*; Endo, Shunsuke; Fujioka, Hiroyuki*; Gudkov, V.*; Ide, Ikuo*; Ino, Takashi*; Ishikado, Motoyuki*; Kambara, Wataru*; et al.
Physical Review C, 109(4), p.044606_1 - 044606_9, 2024/04
Times Cited Count：2 Percentile：61.39(Physics, Nuclear)
-odd/
-odd interactions on the 0.75 eV -wave resonance in 
+
forward transmission determined using a pulsed neutron beamNakabe, Rintaro*; Auton, C. J.*; Endo, Shunsuke; Fujioka, Hiroyuki*; Gudkov, V.*; Hirota, Katsuya*; Ide, Ikuo*; Ino, Takashi*; Ishikado, Motoyuki*; Kambara, Wataru*; et al.
Physical Review C, 109(4), p.L041602_1 - L041602_4, 2024/04
Times Cited Count：1 Percentile：10.98(Physics, Nuclear)Kurita, Keisuke; Iikura, Hiroshi; Tsuchikawa, Yusuke; Kai, Tetsuya; Shinohara, Takenao; Odaira, Naoya*; Ito, Daisuke*; Saito, Yasushi*; Matsubayashi, Masahito
Journal of Physics; Conference Series, 2605, p.012005_1 - 012005_6, 2023/10
The Japan Research Ractor-3 (JRR-3) is operation resumed on February 26, 2021, and the shared use was also restarted in July, 2021. With the resumption of JRR-3 operation, two imaging facilities called TNRF and CNRF have also resumed their utilization. In this presentation, we report the details of these two neutron facilities.
Murase, Kiyoka*; Kataoka, Ryuho*; Nishiyama, Takanori*; Nishimura, Koji*; Hashimoto, Taishi*; Tanaka, Yoshimasa*; Kadokura, Akira*; Tomikawa, Yoshihiro*; Tsutsumi, Masaki*; Ogawa, Yasunobu*; et al.
Journal of Space Weather and Space Climate (Internet), 12, p.18_1 - 18_16, 2022/06
Times Cited Count：3 Percentile：25.39(Astronomy & Astrophysics)We identified two energetic electron precipitation (EEP) events during the growth phase of moderate substorms and estimated the mesospheric ionization rate for an EEP event for which the most comprehensive dataset from ground-based and space-born instruments was available. The mesospheric ionization signature reached below 70 km altitude and continued for ~15 min until the substorm onset, as observed by the PANSY radar and imaging riometer at Syowa Station in the Antarctic region. We also used energetic electron flux observed by the Arase and POES 15 satellites as the input for the air-shower simulation code PHITS to quantitatively estimate the mesospheric ionization rate. Combining the cutting-edge observations and simulations, we shed new light on the space weather impact of the EEP events during geomagnetically quiet times, which is important to understand the possible link between the space environment and climate.
Bh in the 
Cm(
Na,5
)Bh reaction and its decay propertiesHaba, Hiromitsu*; Fan, F.*; Kaji, Daiya*; Kasamatsu, Yoshitaka*; Kikunaga, Hidetoshi*; Komori, Yukiko*; Kondo, Narumi*; Kudo, Hisaaki*; Morimoto, Koji*; Morita, Kosuke*; et al.
Physical Review C, 102(2), p.024625_1 - 024625_12, 2020/08
Times Cited Count：7 Percentile：53.09(Physics, Nuclear)Shinohara, Takenao; Kai, Tetsuya; Oikawa, Kenichi; Nakatani, Takeshi; Segawa, Mariko; Hiroi, Kosuke; Su, Y. H.; Oi, Motoki; Harada, Masahide; Iikura, Hiroshi; et al.
Review of Scientific Instruments, 91(4), p.043302_1 - 043302_20, 2020/04
Times Cited Count：79 Percentile：97.16(Instruments & Instrumentation)Shoji, Eita*; Isogai, Shosei*; Suzuki, Rikuto*; Kubo, Masaki*; Tsukada, Takao*; Kai, Tetsuya; Shinohara, Takenao; Matsumoto, Yoshihiro*; Fukuyama, Hiroyuki*
Scripta Materialia, 175, p.29 - 32, 2020/01
Times Cited Count：24 Percentile：72.98(Nanoscience & Nanotechnology)Kataoka, Ryuho*; Nishiyama, Takanori*; Tanaka, Yoshimasa*; Kadokura, Akira*; Uchida, Herbert Akihito*; Ebihara, Yusuke*; Ejiri, Mitsumu*; Tomikawa, Yoshihiro*; Tsutsumi, Masaki*; Sato, Kaoru*; et al.
Earth, Planets and Space (Internet), 71(1), p.9_1 - 9_10, 2019/12
Times Cited Count：11 Percentile：40.86(Geosciences, Multidisciplinary)Transient ionization of the mesosphere was detected at around 65 km altitude during the isolated auroral expansion occurred at 2221-2226 UT on June 30, 2017. A general-purpose Monte Carlo particle transport code PHITS suggested that significant ionization is possible in the middle atmosphere due to auroral X-rays from the auroral electrons of 
10 keV.
Koyama, Taku*; Ueno, Kazuki*; Sekine, Mariko*; Matsumoto, Yoshihiro*; Kai, Tetsuya; Shinohara, Takenao; Iikura, Hiroshi; Suzuki, Hiroshi; Kanematsu, Manabu*
Materials Research Proceedings, Vol.4, p.155 - 160, 2018/05
Times Cited Count：0 Percentile：0.00(Materials Science, Characterization & Testing)
Nb and 
Ta for chemical studies of element 105, Db, using the GARIS gas-jet systemHuang, M.*; Haba, Hiromitsu*; Murakami, Masashi*; Asai, Masato; Kaji, Daiya*; Kanaya, Jumpei*; Kasamatsu, Yoshitaka*; Kikunaga, Hidetoshi*; Kikutani, Yuki*; Komori, Yukiko*; et al.
Journal of Radioanalytical and Nuclear Chemistry, 304(2), p.845 - 849, 2015/05
Times Cited Count：3 Percentile：22.96(Chemistry, Analytical)A technique to utilize radioisotopes of Nb and Ta was developed for chemical studies of element 105, Db, by coupling a gas-jet transport system to the RIKEN gas-filled recoil ion separator (GARIS). The short-lived Nb and Ta were produced with nuclear reactions using a 
F beam whose energy was the same as that to produce 
Db. Then, they were separated with GARIS and extracted to a chemistry laboratory with the gas-jet transport system. By changing only magnetic field of GARIS and inserting an energy degrader and a shutter for recoil ions, we could deliver the Nb and Ta to a chemistry device for Db without changing other experimental conditions.
Db in the Cm(F,5)Db reaction and decay properties of Db and 
LrHaba, Hiromitsu*; Huang, M.*; Kaji, Daiya*; Kanaya, Jumpei*; Kudo, Yuki*; Morimoto, Koji*; Morita, Kosuke*; Murakami, Masashi*; Ozeki, Kazutaka*; Sakai, Ryutaro*; et al.
Physical Review C, 89(2), p.024618_1 - 024618_11, 2014/02
Times Cited Count：28 Percentile：82.28(Physics, Nuclear)
/Md
reduction potential studied with flow electrolytic chromatographyToyoshima, Atsushi; Li, Z.*; Asai, Masato; Sato, Nozomi; Sato, Tetsuya; Kikuchi, Takahiro; Kaneya, Yusuke; Kitatsuji, Yoshihiro; Tsukada, Kazuaki; Nagame, Yuichiro; et al.
Inorganic Chemistry, 52(21), p.12311 - 12313, 2013/11
Times Cited Count：8 Percentile：33.53(Chemistry, Inorganic & Nuclear)The reduction behavior of mendelevium (Md) was studied using a flow electrolytic chromatography apparatus. By applying appropriate potentials on the chromatography column, the more stable Md is reduced to Md. The reduction potential of the Md + e
Md couple was determined to be -0.16
0.05 V vs. a normal hydrogen electrode.
Ohgama, Kazuya; Ando, Yoko; Yamaguchi, Mika; Ikuta, Yuko; Shinohara, Nobuo; Murakami, Hiroyuki; Yamashita, Kiyonobu; Uesaka, Mitsuru*; Demachi, Kazuyuki*; Komiyama, Ryoichi*; et al.
JAEA-Review 2013-004, 76 Pages, 2013/05
JAEA-Review-2013-004.pdf:13.53MB
JAEA together with the Japan Nuclear Human Resource Development Network (JN-HRD Net), the University of Tokyo (UT) and the Japan Atomic Industrial Forum (JAIF) cohosted the IAEA-Nuclear Energy Management School in Tokai Village, aiming that Japan will be the center of nuclear HRD in the Asian region. In the school, not only lectures by IAEA experts, but also lectures by Japanese experts and technical visits were included for foreign participants. The school contributed to the internationalization of Japanese young professionals, development of nuclear human resource of other countries, and enhancement of cooperation between IAEA and Japan. Additionally, collaborative relationship within JN-HRD Net was strengthened by the school. In this report, findings obtained during the preparatory work and the school period are reported for future international nuclear HRD activities in Japan.
SO
/HNO
mixed solutionLi, Z.*; Toyoshima, Atsushi; Asai, Masato; Tsukada, Kazuaki; Sato, Tetsuya; Sato, Nozomi; Kikuchi, Takahiro; Nagame, Yuichiro; Sch
del, M.; Pershina, V.*; et al.
Radiochimica Acta, 100(3), p.157 - 164, 2012/03
Times Cited Count：14 Percentile：68.20(Chemistry, Inorganic & Nuclear)
Sg in the Cm(
Ne,5)Sg reaction and decay properties of two isomeric states in SgHaba, Hiromitsu*; Kaji, Daiya*; Kudo, Yuki*; Morimoto, Koji*; Morita, Kosuke*; Ozeki, Kazutaka*; Sakai, Ryutaro*; Sumita, Takayuki*; Yoneda, Akira*; Kasamatsu, Yoshitaka*; et al.
Physical Review C, 85(2), p.024611_1 - 024611_11, 2012/02
Times Cited Count：56 Percentile：90.87(Physics, Nuclear)Two isomeric states in Sg, i.e, Sg
and Sg
were produced in the Cm(Ne,5) reaction. Decay properties of Sg
were investigated with a rotating-wheel apparatus for 
and spontaneous fission (SF) spectrometry under low background condition attained by a gas-jet transport system coupled to the RIKEN gas-filled recoil ion separator. Based on genetically correlated - (-) and -SF decay chains, 18 and 24 events were assigned to Sg and Sg, respectively. The half-life and -particle energy of Sg were measured to be 
s and 
MeV, respectively, and those of Sg were 
s and 
MeV.
Yanagie, Hironobu*; Kumada, Hiroaki*; Nakamura, Takemi; Higashi, Shushi*; Ikushima, Ichiro*; Morishita, Yasuyuki*; Shinohara, Atsuko*; Fujiwara, Mitsuteru*; Suzuki, Minoru*; Sakurai, Yoshinori*; et al.
Proceedings of 14th International Congress on Neutron Capture Therapy (ICNCT-14) (CD-ROM), p.157 - 160, 2010/10
Kasamatsu, Yoshitaka*; Toyoshima, Atsushi; Asai, Masato; Tsukada, Kazuaki; Li, Z.; Ishii, Yasuo; Tome, Hayato*; Sato, Tetsuya; Kikuchi, Takahiro; Nishinaka, Ichiro; et al.
Chemistry Letters, 38(11), p.1084 - 1085, 2009/10
Times Cited Count：17 Percentile：50.63(Chemistry, Multidisciplinary)We report on the characteristic anion-exchange behavior of the superheavy element dubnium (Db) with atomic number Z = 105 in HF/HNO solution at the fluoride ion concentration [F] = 0.003 M. The result clearly demonstrates that the fluoro complex formation of Db is significantly different from that of the group-5 homologue Ta in the 6th period of the periodic table while the behavior of Db is similar to that of the lighter homologue Nb in the 5th period.
N nano-particles for magnetic recording tapeOku, Takayuki; Kikuchi, Takayuki*; Shinohara, Takenao; Suzuki, Junichi; Ishii, Yuya*; Takeda, Masayasu; Kakurai, Kazuhisa; Sasaki, Yuji*; Kishimoto, Mikio*; Yokoyama, Makoto*; et al.
Physica B; Condensed Matter, 404(17), p.2575 - 2577, 2009/09
Times Cited Count：8 Percentile：35.11(Physics, Condensed Matter)The microscopic determination of the magnetic moment in the FeN nano-particles by means of polarized neutron diffraction experiment is reported. These particles had been developed by industrial researchers for use in high-density magnetic tape, and the particles were coated with proprietary nonmagnetic material. Polarized neutrons were used to measure the magnetic-nuclear interference contributions and, given the known crystal structure, the detailed analysis allowed to determine the magnetic moments on the different Fe-sites. The future perspectives of this technique using the high-intensity powder instrument in combination with pulsed magnetic high-field at J-PARC including the possible industrial application is discussed.
