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K
Li
)NbO
synthesized by malic acid complex solution methodYoneda, Yasuhiro; Takada, Eri*; Nagai, Haruka*; Kikuchi, Takeyuki*; Morishita, Masao*; Kobune, Masafumi*
Japanese Journal of Applied Physics, 56(10S), p.10PB07_1 - 10PB07_7, 2017/10
Times Cited Count：3 Percentile：15.1(Physics, Applied)A monoclinic phase was discovered in (NaKLi)NbO solid solution ceramics grown by a malic acid complex solution method. The average and local structures of this monoclinic phase were analyzed by synchrotron X-ray measurements. The local structure can be reproduced by assuming a rhombohedral model, that is the same local structure of KNbO. The results demonstrate that the monoclinic average structure is observed as a disordered rhombohedral structure.
KLi)NbO solid solutions by malic acid complex solution methodNakai, Tomoaki*; Kobune, Masafumi*; Nagamoto, Takeru*; Kikuchi, Takeyuki*; Yoneda, Yasuhiro
Transactions of the Materials Research Society of Japan, 41(3), p.251 - 254, 2016/09
Solid solutions of NaNbO and KNbO are the candidate for non-Pb piezoelectric materials. It is difficult to obtain dense ceramics owing to the difference of their calcination temperature. We developed the malic acid complex method to obtain the (NaKLi)NbO to obtain a high-quality ceramics sample. It was found that (NaKLi)NbO lies complicated phase boundaries; one is the structural phase boundary between NaNbO and KNbO, the other is that between (Na,K)NbO mixture and LiNbO, which is a sintering additive.
NaTiO, BiNa
Li
TiO, and 0.95BiNaTiO 
0.05BaMn
V
OYoneda, Yasuhiro; Nagamoto, Takeru*; Nakai, Tomoaki*; Kobune, Masafumi*
Transactions of the Materials Research Society of Japan, 41(2), p.197 - 200, 2016/06
BiNaTiO (BNT) has been investigated as a lead-free piezoelectric material. We have already performed structure analysis of BNT. The average structure of BNT with low-temperature synthesis is a rhombohedral structure and it becomes a monoclinic structure as the synthesized temperature increases. Our local structure analysis indicated that the 
-site atoms of Bi and Na displaced toward different position depending on the lattice expansion and construction. We synthesized BNT crystals with various substitution and performed local structure analysis to examine the hypothesis. The local structure analysis revealed that the substitution effect on BNT can be explained by our hypothesis.
Chikazawa, Yoshitaka; Enuma, Yasuhiro; Kisohara, Naoyuki; Yamano, Hidemasa; Kubo, Shigenobu; Hayafune, Hiroki; Sagawa, Hiroshi*; Okamura, Shigeki*; Shimakawa, Yoshio*
Proceedings of 2012 International Congress on Advances in Nuclear Power Plants (ICAPP '12) (CD-ROM), p.677 - 686, 2012/06
Evaluation of Earthquake and Tsunami on JSFR has been analyzed. For seismic design, safety components are confirmed to maintain their functions even against recent strong Earthquakes. As for Tsunami, some parts of reactor building might be submerged including component cooling water system whose final heat sink is sea water. However, in the JSFR design, safety grade components are independent from component cooling water system (CCWS). The JSFR emergency power supply adopts a gas turbine system with air cooling, since JSFR does not basically require quick start-up of the emergency power supply thanks to the natural convection DHRS. Even in case of long station blackout, the DHRS could be activated by emergency batteries or manually and be operated continuously by natural convection.
Kurome, Kazuya*; Kawamura, Masaya*; Enuma, Yasuhiro*; Tsujita, Yoshihiro*; Sato, Mitsuru*; Futagami, Satoshi; Hayafune, Hiroki
Proceedings of International Conference on Fast Reactors and Related Fuel Cycles (FR 2009) (CD-ROM), 11 Pages, 2012/00
Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Akiya, Takahiro*; Kato, Hiroaki*; Une, Yasuhiro*; Sagawa, Masato*
Proceedings of 21st International Workshop on Rare-Earth Permanent Magnets and their Applications (REPM 2010), p.161 - 164, 2010/08
We performed small-angle neutron scattering (SANS) measurements of Nd-Fe-B sintered magnets to get information on the averaged internal microstructure of Nd-Fe-B sintered magnets including the interfacial structure which is a key parameter to achieve a high-coercivity Dy-free Nd-Fe-B sintered magnet. SANS patterns from the Nd-Fe-B sintered magnets measured with a two-dimensional detector of a small-angle neutron scattering spectrometer SANS-J-II in the research reactor JRR-3 were sensitive to the sintering and annealing condition of the samples. These results indicate that the SANS measurement is a promising tool to investigate the correlation between the coercivity and the internal microstructure of Nd-Fe-B sintered magnets.
Hayafune, Hiroki; Enuma, Yasuhiro; Soman, Yoshindo; Konomura, Mamoru; Mizuno, Tomoyasu; Igawa, Kenichi*
JNC TN9400 2004-054, 339 Pages, 2004/08
JNC-TN9400-2004-054.pdf:24.71MB
Concepts of the reactor, SG and main coolant pump have been studied considering maintainability and aseismic capability, which is a medium size pool type lead-bismuth cooled reactor. The results are following.(1) Reconsideration of reactor design concepts concerning maintainability. In pursuit of good reactor maintainability, the structural concepts of SG, UIS and core support structures have been changed to be drawn up above the upper area of the reactor system. After a few decade of interval, lead-bismuth inventory in the reactor vessel shall be fully drained for easy ISI operation of in-vessel main components such as core support structures. From the viewpoint of the reactor aseismic capability, the axial length of reactor vessel was reduced and the reactor vessel support location was changed from the top hanging to the circumference of the vessel.(2) SG concept selection in conjunction with a compact reactor vessel.The concept of SG consisting of a once through type with helical coil tube is selected. 6 units of a small scale SG are arranged on a reactor roof deck along the peripheral direction, in addition to 3 units of a centrifugal mechanical pump.(3) Aseismic structural integrity of the reactor components. Aseismic structural integrity of the reactor vessel, core support structures, UIS, FHM, SG and the main pumps has been vigorously examined respectively. These components besides FHM could keep the aseismic structural integrity for strong S2 earthquake under the design condition FHM could also keep the integrity for S1 earthquake.(4) Safety evaluation. Thermal translents following loss of flow type accident due to plant total blackout and typical manual reactor trip incident, have been evaluated to assure the plant safety design, by analyzing thermal hydraulic behavior of transients concerning core flow rate and temperatures of the plant cooling system. *Loss of flow accident due to plant total blackout. The reactor coolant pumps shall be tripped and the
CuHara, Keigo*; Adachi, Takeshi*; Akimune, Hidetoshi*; Daito, Izuru*; Fujimura, Hisako*; Fujita, Yoshitaka*; Fujiwara, Mamoru; Fushimi, Kenichi*; Hara, Kaoru*; Harakeh, M. N.*; et al.
Physical Review C, 68(6), p.064612_1 - 064612_9, 2003/12
Times Cited Count：11 Percentile：58.08(Physics, Nuclear)no abstracts in English
Enuma, Yasuhiro; Hayafune, Hiroki; Soman, Yoshindo; Konomura, Mamoru; Mizuno, Tomoyasu; Sakai, Takaaki
JNC TN9400 2003-081, 234 Pages, 2003/09
JNC-TN9400-2003-081.pdf:13.34MB
Main issues of structural integrity, seismic integrity and operation are studied to confirm feasibilities of the medium size lead-bismuth cooled reactor as a candidate for one of the concepts of fast reactor in the feasibility studies on commercialized FBR cycle system. The results are following. (1) Integrity under loading of earthquake (a) Reactor system: Seismic integrity of the reactor is confirmed. (b) Upper core structures and fuel exchanging machine: Those structures are necessary for increasing stiffness by bonding. (2) Structural integrity for thermal loading Characteristics of both the medium size lead-bismuth cooled reactor and the large size sodium cooled reactor in the feasibility studies are arranged and structural integrity for thermal loading is evaluated about particular phenomena of thermal stratification and thermal striping. (3) Operation Feasibility of the natural circulation operation is confirmed. (a) Water-steam supply system concerned with control system (b) Control characteristics and transient characteristics of lead-bismuth reactor (c) Initial start-up operation concerned with preheating and charging of coolant (4) Safty Core integrity on SG tube rupture is evaluated to be confirmed its safety, by analyzing thermal hydraulic behavior of transient of power, flow and temperature, by calculating characteristics of core and by evaluating additional reactivity by steam coming into core region. (5) Internal core structures design and system power balance design.
Hayafune, Hiroki; Enuma, Yasuhiro; Mizuno, Tomoyasu; Soman, Yoshindo; Konomura, Mamoru; Mito, Makoto*; Tanji, Mikio*
Roshia Kosokuro Kokusai Kaigi, 0 Pages, 2003/00
Focusing on the cover layer materials (as the Radon Barrier Materials), which could have the effect to restrain the radon from scattering into the air and the effect of the radiation shielding, we produced the radon barrier materials with crude bentonite on an experimental basis, using the rotary type comprehensive unit for grinding and mixing, through which we carried out the evaluation of the characteristics thereof.
Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Akiya, Takahiro*; Kato, Hiroaki*; Une, Yasuhiro*; Sagawa, Masato*
no journal, ,
We have been investing the correlation between the coercive force and the averaged internal structure of Neodymium-Iron-Boron (Nd-Fe-B) sintered magnets using the small-angle neutron scattering (SANS) spectrometer, SANS-J-II installed at the beam hall of the research reactor JRR-3 in Tokai. The correlation is a clue to achieve the less or Dysprosium (Dy)-free Nd-Fe-B sintered magnets with high coercivity for high-temperature application. In this talk, we report that the coercivity is very sensitive to the averaged diameter of powder and the temperature in sintering process, and that the SANS patterns on 2-dimensional position-sensitive detector (2D-PSD) are also sensitively changed following the sintering condition.
Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Akiya, Takahiro*; Kato, Hiroaki*; Une, Yasuhiro*; Sagawa, Masato*
no journal, ,
A Neodymium Iron Boron (Nd-Fe-B) sintered magnet is the most powerful permanent magnet among the commercially available ones. Because of the low 
, the coercivity of this magnet rapidly reduces above the room temperature. It is well known that substitution of dysprosium (Dy) for a part of Nd recovers the coercivity at the high temperatures. There are two key parameters to enhance the coercivity of Nd-Fe-B sintered magnets without the addition of Dy: grain refinement of microstructure in the magnets, and the microstructural control at the interface between Nd
Fe
B and Nd-rich phases surrounding the main phase. Small-angle neutron scattering (SANS) is very powerful tool to investigate such internal structures. We performed SANS measurements of the Nd-Fe-B sintered magnets using unpolarized and polarized neutrons on SANS-J-II installed at JRR-3. The information is essential to the achievement of the high-coercivity Dy-free Nd-Fe-B sintered magnet.
Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Akiya, Takahiro*; Kato, Hiroaki*; Une, Yasuhiro*; Sagawa, Masato*
no journal, ,
A neodymium iron boron (Nd-Fe-B) sintered magnet is the most powerful permanent magnet among the commercially available ones. Dysprosium (Dy), however, has to be added in Nd-Fe-B sintered magnets to keep the high 
above the room temperature or high-temperature applications. Dy-less or Dy-free Nd-Fe-B sintered magnets are now highly demanded because Dy is one of the rare metals. We performed small-angle neutron scattering (SANS) measurements of sintered Nd-Fe-B sintered magnets to elucidate the correlation between the coercivity and averaged internal structures of this magnet. Such correlation is a clue to achieve the Dy-less or Dy-free Nd-Fe-B sintered magnets. In this talk, we report the detailed results of the experiments and the correlation revealed by the SANS measurements.
Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Akiya, Takahiro*; Kato, Hiroaki*; Une, Yasuhiro*; Sagawa, Masato*
no journal, ,
no abstracts in English
Futagami, Satoshi; Hayafune, Hiroki; Enuma, Yasuhiro*; Ogumo, Shinya*; Hirayama, Tomoyuki*; Murakami, Hisatomo*
no journal, ,
no abstracts in English
Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Akiya, Takahiro*; Kato, Hiroaki*; Une, Yasuhiro*; Sagawa, Masato*
no journal, ,
no abstracts in English
Shimazaki, Masanori; Hayafune, Hiroki; Futagami, Satoshi; Enuma, Yasuhiro*; Kawamura, Masaya*; Ogumo, Shinya*
no journal, ,
no abstracts in English
Suzuki, Junichi; Yamaguchi, Daisuke; Akiya, Takahiro*; Kato, Hiroaki*; Une, Yasuhiro*; Sagawa, Masato*; Takeda, Masayasu
no journal, ,
no abstracts in English
Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Akiya, Takahiro*; Kato, Hiroaki*; Une, Yasuhiro*; Sagawa, Masato*
no journal, ,
no abstracts in English
Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Akiya, Takahiro*; Kato, Hiroaki*; Une, Yasuhiro*; Sagawa, Masato*
no journal, ,
no abstracts in English
