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Kato, Atsushi; Kubo, Shigenobu; Chikazawa, Yoshitaka; Miyagawa, Takayuki*; Uchita, Masato*; Suzuno, Tetsuji*; Endo, Junji*; Kubo, Koji*; Murakami, Hisatomo*; Uzawa, Masayuki*; et al.
Proceedings of International Conference on Fast Reactors and Related Fuel Cycles; Sustainable Clean Energy for the Future (FR22) (Internet), 11 Pages, 2022/04
The authors are carrying out conceptual design studies for a pool-type sodium-cooled fast reactor. There are main challenges such as measures against severe earthquake in Japan, thermal hydraulic in a reactor vessel (RV), a decay heat removal system design. When the JP-pool SFR of 650 MWe is installed in Japan, it shall be designed against the severe seismic conditions. Additionally, a newly three-dimensional seismic isolation system is under development.
Shinto, Katsuhiro; Ichikawa, Masahiro; Takahashi, Yasuyuki*; Kubo, Takashi*; Tsutsumi, Kazuyoshi; Kikuchi, Takayuki; Kasugai, Atsushi; Sugimoto, Masayoshi; Gobin, R.*; Girardot, P.*; et al.
Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1009 - 1012, 2014/10
The prototype accelerator is being developed as an engineering validation for the International Fusion Materials Irradiation Facility (IFMIF) equipped with an accelerator-driven-type neutron source for developing fusion reactor materials. This prototype accelerator is a deuteron linear accelerator consisting of an injector, an RFQ, a superconducting linac and their auxiliaries. It aims to produce a CW D
beam with the energy and current of 9 MeV/125 mA. The injector test was completed at CEA/Saclay in 2012 for producing a CW H beam and a CW D beam with the energy and current of 100 keV/140 mA. After the beam test at CEA/Saclay, the injector was transported to the International Fusion Energy Research Centre (IFERC) located in Rokkasho, Aomori, Japan. In the end of 2013, installation of the injector was started at IFERC for the injector beam test beginning from summer 2014 in order to obtain better beam qualities to be satisfied with the injection and acceleration of the following accelerators. In this paper, some results of the injector beam test performed at CEA/Saclay and the status quo of the installation of the injector at IFERC are presented.
Machida, Akihiko; Honda, Mitsunori*; Hattori, Takanori; Sano, Asami; Watanuki, Tetsu; Katayama, Yoshinori; Aoki, Katsutoshi; Komatsu, Kazuki*; Arima, Hiroshi*; Oshita, Hidetoshi*; et al.
Physical Review Letters, 108(20), p.205501_1 - 205501_5, 2012/05
Times Cited Count：21 Percentile：70.52(Physics, Multidisciplinary)Hydrogen atoms absorbed in a metal occupy the interstitial sites of the metal lattice. In an fcc metal lattice, each metal atom has two tetrahedral (T) and one octahedral (O) sites that can accommodate hydrogen. Rare-earth metal La forms T-site occupied LaH
and fully occupied LaH
. O-site occupied or NaCl-type monohydride has yet to be reported for rare-earth metals. Previous X-ray diffraction measurements revealed the pressure-induced decomposition of an fcc-LaH
into H-rich and H-poor phases around 11 GPa. The present neutron diffraction measurements on LaD confirm the formation of NaCl-type LaD as a counterpart of the D-rich LaD
by disproportionation. First-principle calculations demonstrate that the NaCl-type LaH is stabilized at high pressures. Finding the NaCl-type LaH will pave the way for investigations on the site-dependent nature of hydrogen-metal interactions.
Hs and 
HsSato, Nozomi; Haba, Hiromitsu*; Ichikawa, Takatoshi*; Kaji, Daiya*; Kudo, Yuki*; Morimoto, Koji*; Morita, Kosuke*; Ozeki, Kazutaka*; Sumita, Takayuki*; Yoneda, Akira*; et al.
Journal of the Physical Society of Japan, 80(9), p.094201_1 - 094201_7, 2011/09
Times Cited Count：16 Percentile：65.66(Physics, Multidisciplinary)Decay properties of Hs and Hs produced in the 
Pb(
Fe, 
) [
=1, 2] reactions were studied using a gas-filled recoil ion separator at the linear accelerator facility of RIKEN. A total of 6 decay chains were assigned to Hs. Cross sections for the Hs production in the 
Pb(Fe,
) and 
Pb(Fe,
) reactions were measured to be 
pb and 
pb, respectively. The isotope Hs decayed with a half-life of 
ms by 
-particle emission and spontaneous fission. The -particle energy of Hs was observed at 10.61
0.04 and 10.800.08 MeV. The spontaneous fission branch of Hs was found to be 
.
Kamakura, Nozomu; Takeda, Yukiharu; Saito, Yuji; Yamagami, Hiroshi; Tsubota, Masami*; Paik, B.*; Ichikawa, Takayuki*; Kojima, Yoshitsugu*; Muro, Takayuki*; Kato, Yukako*; et al.
Physical Review B, 83(3), p.033103_1 - 033103_4, 2011/01
Times Cited Count：6 Percentile：27.76(Materials Science, Multidisciplinary)The electronic structure of lithium amide, which is lightweight complex hydride expected as a high-capacity hydrogen storage material, is investigated by N 1
soft X-ray emission spectroscopy (XES) and absorption spectroscopy (XAS). The overall feature of the electronic structure of lithium amide by the XES and XAS is consistent with the band calculation, while the strongly hybridized state with H 1 is located at higher binding energy than the band calculation.
-FeSiMaeda, Yoshihito; Ichikawa, Takayuki*; Jonishi, Takafumi*; Narumi, Kazumasa
Physics Procedia, 11, p.83 - 86, 2011/00
Times Cited Count：0 Percentile：0.00(Optics)
-edgesIshimatsu, Naoki*; Sasada, Ryohei*; Maruyama, Hiroshi*; Ichikawa, Takayuki*; Miyaoka, Hiroki*; Kimura, Toru*; Tsubota, Masami*; Kojima, Yoshitsugu*; Tsumuraya, Takao*; Oguchi, Tamio*; et al.
Journal of Physics; Conference Series, 190, p.012070_1 - 012070_4, 2009/11
Times Cited Count：5 Percentile：78.54(Physics, Condensed Matter)We have investigated the effect of hydrogenation on La 
and 
electronic states in metallic LaH
by X-ray absorption near edge structure at the La -edges. As the hydrogen content increases from 0 to 2.6, white-line intensity at the La 
-edges shows a remarkable increase in the range of 
2.0. This is interpreted as the increase in La hole induced by interstitial H atoms on the octahedral sites. On the other hand, the shoulder structure at the La 
-edge disappears in the process of = 0.0 
2.0, indicating that the 
-
hybridization is weakened by H atoms on the tetrahedral sites. This study demonstrates that H atoms on the two interstitial H sites provide different contribution to the modification of the electronic states.
Bh and 
Db produced in the 
Cm + 
Na reactionMorita, Kosuke*; Morimoto, Koji*; Kaji, Daiya*; Haba, Hiromitsu*; Ozeki, Kazutaka*; Kudo, Yuki*; Sato, Nozomi*; Sumita, Takayuki*; Yoneda, Akira*; Ichikawa, Takatoshi*; et al.
Journal of the Physical Society of Japan, 78(6), p.064201_1 - 064201_6, 2009/06
Times Cited Count：30 Percentile：77.51(Physics, Multidisciplinary)Decay properties of an isotope Bh and its daughter nucleus Db produced by the Cm(Na,5) reaction were studied by using a gas-filled recoil separator coupled with a position-sensitive semiconductor detector. Bh was clearly identified from the correlation of the known nuclide, Db. The obtained decay properties of Bh and Db are consistent with those observed in the 
113 chain, which provided further confirmation of the discovery of 113.
HsKaji, Daiya*; Morimoto, Koji*; Sato, Nozomi*; Ichikawa, Takatoshi*; Ideguchi, Eiji*; Ozeki, Kazutaka*; Haba, Hiromitsu*; Koura, Hiroyuki; Kudo, Yuki*; Ozawa, Akira*; et al.
Journal of the Physical Society of Japan, 78(3), p.035003_1 - 035003_2, 2009/03
A new hassium isotopes Hs is directly produced for the first time. The experiment was performed at the linear accelerator (RILAC) facility in RIKEN (the Institute of Physical and Chemical Research) from Jun. 19 to 25. In the 25-h irradiation of Fe on 
Pb and 46-h irradiation of 
Fe on Pb, 8 decay chains and 1 decay chain, respectively, were observed. All decay chains were assigned to subsequent decays from Hs. The half-life of Hs is 0.60
ms. In this experiment, the total beam dose was 
ions for Fe and 
ions for Fe. The production cross section corresponding to 8 decay events and 1 decay chain was deduced to be 21
pb and 1.6
pb by assuming that the transmission of the system is 80%.
HsKaji, Daiya*; Morimoto, Koji*; Sato, Nozomi*; Ichikawa, Takatoshi*; Ideguchi, Eiji*; Ozeki, Kazutaka*; Haba, Hiromitsu*; Koura, Hiroyuki; Kudo, Yuki*; Ozawa, Akira*; et al.
Journal of the Physical Society of Japan, 78(3), p.035003_1 - 035003_2, 2009/03
Times Cited Count：3 Percentile：25.59(Physics, Multidisciplinary)A new neutron deficient hassium (
=108) isotope of Hs was identified via two different reactions of Pb(Fe,n) and Pb(Fe,n) by using a gas-filled recoil separator GARIS at June 2008. During the 25-h irradiation of Pb with the Fe beam and 46-h irradiation of Pb with the Fe beam, 8 decay chains and 1 decay chain, respectively, have been observed. The half-life of Hs is 0.60
ms. In this experiment, the total beam doses of the Fe and Fe was 4.1
10
ions and 6.210 ions, respectively. The production cross sections corresponding to the 8 decay chains and 1 decay chain have been deduced to be 21 pb and 1.6 pb by assuming the transmission of the system to be 80%.
Hs, 
Sg, and 
RfSato, Nozomi*; Haba, Hiromitsu*; Ichikawa, Takatoshi*; Ideguchi, Eiji*; Kaji, Daiya*; Koura, Hiroyuki; Kudo, Yuki*; Morimoto, Koji*; Morita, Kosuke*; Ozawa, Akira*; et al.
RIKEN Accelerator Progress Report, Vol.42, P. 16, 2009/00
New Decay Properties of Hs and its -decay daughter nuclei were studied by using reactions of Pb(Fe,2n) and Pb(Fe,n) by using a gas-filled recoil ion separator, GARIS at RIKEN. We observed three correlated events in irradiation of Fe on Pb, and eight events in irradiation of Fe on Pb. A half-life was deduced to be 0.90
. We assigned these eleven events to be the decays of Hs. We found different decay-chain events of Hs from a previous report. One is a long-lived -decay of Sg with 180
ms of half-life. Another is a long-lived -decay of Rf with 10.4
s of half-life. For Sg and Rf, the decay of such a long-lived state have not been reported. These are the first observations of isomerism in Sg and Rf.
Maki, Takashi*; Ichikawa, Hajime*; Asao, Takayuki*; Horiuchi, Nobutake*
JNC TJ9400 2002-004, 228 Pages, 2001/02
JNC-TJ9400-2002-004.PDF:9.97MB
We developed two computer codes to evaluate fuel cycle requirements of FR systems, which were selected in "the feasibility studies on commercialized FBR cycle systems". One code (CODE for material balance analysis) is to calculate the material balance data to evaluate the characteristics of each candidate. The other is to calculate the time-series data of material balance of fuel cycle as a whole, to evaluate an optimum scenario of FR systems introduction. The main characteristics of these codes are as follows: (1) Common function of both codes (a) They execute burn up calculation using characteristics values of reactor calculated with ORIGEN2 code. And they adjust Pu content using a concept of physical accounting method for adjusted fissile enrichment. (b) They simulate 18 type of FR systems, 10 reactor types and 6 reprocessing types. (2) Function of CODE for material balance analysis (a) It calculates nuclide inventory and thermal power, radioactivity, radio-toxicity in the waste and environmental release. (b) It evaluates safety of geological disposal of HLW and TRU waste (iodine waste) with simplified safety estimation method. (3) Function of CODE for time-series analysis (a) In addition to FR systems, it simulates 4 type of LWR systems and 5 type of Pu-Thermal LWR systems. (b)It calculates the Pu demand-and-supply situation. The precision of these codes was checked and verified by using other code result. Then we investigation characteristics of each FR system by evaluating material balance of fuel cycle. In addition we clarified differences between scenarios of introduction of FR systems.
113 produced by the 
Bi(
Zn,n)113 reactionMorimoto, Koji*; Morita, Kosuke*; Kaji, Daiya*; Haba, Hiromitsu*; Ozeki, Kazutaka*; Kudo, Yuki*; Sato, Nozomi; Sumita, Takayuki*; Yoneda, Akira*; Ichikawa, Takatoshi*; et al.
no journal, ,
We performed the experiment to synthesize an isotope of the element 113 produced by a Bi(Zn,n)113 reaction using a gas-filled recoil ion separator (GARIS) at RIKEN. Two decay chains were observed, and assigned to those originating from an isotope 113. Both chains were connected into the previously known decays of Bh and Db via previously unknown decays of 113, 
Rg, and 
Mt. Although the Bh was known nuclide, a number of atoms reported so far was limited. In order to study more precise decay property of the Bh, we performed the direct production of Bh by the Cm(Na,5n)Bh reaction. In this experiment, the Bh was clearly identified from the correlation of the nuclide, Db. The obtained decay properties of Bh and Db are consistent with those observed in the 113 chain, which provided further confirmation of the discovery of 113.
by using a soft X-ray emission spectroscopyMizumaki, Masaichiro*; Agui, Akane; Uozumi, Takayuki*; Ichikawa, Noriya*; Shimakawa, Yuichi*
no journal, ,
no abstracts in English
Machida, Akihiko; Honda, Mitsunori; Hattori, Takanori; Sano, Asami; Watanuki, Tetsu; Katayama, Yoshinori; Aoki, Katsutoshi; Komatsu, Kazuki*; Arima, Hiroshi; Oshita, Hidetoshi*; et al.
no journal, ,
Formation of an NaCl-type mono-deuteride LaD has been found by neutron diffraction experiments at high pressure. The NaCl-type structure has been reported for alkaline hydrides and transition metal hydrides, but not for rare-earth metal hydrides. The NaCl-type mono-hydride is formed in rare-earth metals for the first time. Lanthanum mono-deuteride is formed as a result of the phase separation of the di-deuteride under high pressure. This result suggests that the three different hydrides, mono-, di-, and tri-hydrides, with the fcc metal lattice are realized. The hydrogen atoms occupy only O-sites, only T-sites and both O-sites and T-sites in the mono-, di-, and tri-hydrides, respectively. Hence, it is expected that the H-M bonding nature is different for each hydride.
Kamakura, Nozomu; Takeda, Yukiharu; Okane, Tetsuo; Fujimori, Shinichi; Saito, Yuji; Yamagami, Hiroshi; Miyaoka, Hiroki*; Tsubota, Masami*; Ichikawa, Takayuki*; Kojima, Yoshitsugu*; et al.
no journal, ,
no abstracts in English
Kamakura, Nozomu; Yamagami, Hiroshi; Takeda, Yukiharu; Okane, Tetsuo; Saito, Yuji; Miyaoka, Hiroki*; Tsubota, Masami*; Ichikawa, Takayuki*; Kojima, Yoshitsugu*; Muro, Takayuki*; et al.
no journal, ,
In this research, the electronic states of the insulator alkali metal amide (
, 
) and alkaline earth metal amide (
), which are lightweight complex hydrides being considered as a high-capacity hydrogen storage material, are investigated by the soft X-ray emission (XES)and absorption spectroscopies. The sharp three peak structure commonly observed in the XES spectrum of alkali metal amides shows the localized character of the valence electrons, while the importance of the number of the amide ion is shown by the XES spectrum of which is clearly different from that of alkali metal amide. The comparison with the band calculation clarifies the electronic sates of .
Kamakura, Nozomu; Takeda, Yukiharu; Yamagami, Hiroshi; Miyaoka, Hiroki*; Tsubota, Masami*; Ichikawa, Takayuki*; Kojima, Yoshitsugu*; Muro, Takayuki*; Kinoshita, Toyohiko*
no journal, ,
Metal amide has been attracted much attention as a lightweight hydride being considered for high capacity hydrogen storage materials. In this research, the electronic states of the insulator alkali metal amide (KNH, NaNH) and alkaline earth metal amide (Ca(NH), Mg(NH)) are investigated by the soft X-ray emission spectroscopy (XES) and absorption spectroscopy (XAS) in the total fluorescence yield mode. The localized character of the valence electrons is shown by the sharp three peak structure commonly observed in the XES spectrum of alkali metal amide. The localized character of the valence electrons is shown by the sharp peak structure commonly observed in the XES spectrum of alkali metal amide. The broadening of the N 2p states by the hybridization is observed in the XES spectrum of the alkaline earth metal amide. Decomposition temperature of the metal amide is found to relate to the character of the chemical bond observed in the XAS.
Aoki, Katsutoshi; Machida, Akihiko; Honda, Mitsunori; Hattori, Takanori; Sano, Asami; Watanuki, Tetsu; Katayama, Yoshinori; Komatsu, Kazuki*; Arima, Hiroshi; Otomo, Toshiya*; et al.
no journal, ,
Rare-earth metal La forms T-site occupied fcc-LaH and fully occupied fcc-LaH
, the former is metallic and the latter is insulating. Our previous synchrotron X-ray and infrared measurements revealed that the dihydride decomposed into hydrogen-rich and hydrogen-poor phases upon compression to 11 GPa at ambient temperature; the hydrogen rich phase was identified as LaH but the hydrogen composition and occupation sites of the hydrogen-poor phase remained undetermined. The crystal structure of the hydrogen-poor phase was investigated for LaD by neutron diffraction measurement with a total diffractometer NOVA at J-PARC. The formation of NaCl-type LaD as a counterpart of LaD by the decomposition was confirmed from the diffraction profiles. First-principle enthalpy and lattice dynamic calculations have demonstrated that the NaCl-type LaH is stabilized at high pressures.
Sato, Tetsuya; Sato, Nozomi; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Oe, Kazuhiro; Kaneya, Yusuke*; Kojima, Takayuki*; Nagame, Yuichiro; Sch
del, M.; et al.
no journal, ,
The first ionization potential (IP) of the heaviest actinide lawrencium (Lr) is predicted to be lower than those of other actinides. To determine the IP of Lr based on the surface ionization technique, we have developed a surface ionization ion source coupled to a gas-jet transport system for the Isotope Separator On-Line at the JAEA tandem accelerator facility. We measured ionization efficiencies of short-lived lanthanides isotopes as a function of ion-source temperature as a model experiment of Lr.
