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Kawasaki, Kohei; Ono, Takanori; Shibanuma, Kimikazu; Goto, Kenta; Aita, Takahiro; Okamoto, Naritoshi; Shinada, Kenta; Ichige, Hidekazu; Takase, Tatsuya; Osaka, Yuki; et al.
JAEA-Technology 2022-031, 91 Pages, 2023/02
JAEA-Technology-2022-031.pdf:6.57MB
The document for back-end policy opened to the public in 2018 by Japan Atomic Energy Agency (hereafter, JAEA) states the decommissioning of facilities of Nuclear Fuel Cycle Engineering Laboratories and JAEA have started gathering up nuclear fuel material of the facilities into Plutonium Fuel Production Facilities (hereafter, PFPF) in order to put it long-term, stable and safe storage. Because we planned to manufacture scrap assemblies almost same with Monju fuel assembly using unsealed plutonium-uranium mixed-oxide (hereafter, MOX) powder held in PFPF and transfer them to storage facilities as part of this "concentration" task of nuclear fuel material, we obtained permission to change the use of nuclear fuel material in response to the new regulatory Requirements in Japan for that. The amount of plutonium (which is neither sintered pellets nor in a lidded powder-transport container) that could be handled in the pellet-manufacturing process was limited to 50 kg Pu or less in order to decrease the facility risk in this manufacture. Therefore, we developed and installed the "MOX weighing and blending equipment" corresponding with small batch sizes that functioned in a starting process and the equipment would decrease handling amounts of plutonium on its downstream processes. The failure data based on our operation and maintenance experiences of MOX fuel production facilities was reflected in the design of the equipment to further improve reliability and maintainability in this development. The completed equipment started its operation using MOX powder in February 2022 and the design has been validated through this half-a-year operation. This report organizes the knowledge obtained through the development of the equipment, the evaluation of the design based on the half-a-year operation results and the issues in future equipment development.
Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.
Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03
Times Cited Count：43 Percentile：96.93(Astronomy & Astrophysics)Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 
C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.
Harii, Kazuya; Seo, Y.-J.*; Tsutsumi, Yasumasa*; Chudo, Hiroyuki; Oyanagi, Koichi*; Matsuo, Mamoru; Shiomi, Yuki*; Ono, Takahito*; Maekawa, Sadamichi; Saito, Eiji
Nature Communications (Internet), 10, p.2616_1 - 2616_5, 2019/06
Times Cited Count：28 Percentile：81.46(Multidisciplinary Sciences)
Fe
O
cantileversSeo, Y.-J.*; Harii, Kazuya; Takahashi, Ryo*; Chudo, Hiroyuki; Oyanagi, Koichi*; Qiu, Z.*; Ono, Takahito*; Shiomi, Yuki*; Saito, Eiji
Applied Physics Letters, 110(13), p.132409_1 - 132409_4, 2017/03
Times Cited Count：12 Percentile：50.89(Physics, Applied)We have fabricated ferrite cantilevers in which their vibrational properties can be controlled by external magnetic fields. Submicron-scale cantilever structures were made from YFeO films by physical etching combined with the use of a focused ion beam milling technique. We found that the cantilevers exhibit two resonance modes which correspond to horizontal and vertical vibrations. Under external magnetic fields, the resonance frequency of the horizontal mode increases, while that of the vertical mode decreases, quantitatively consistent with our numerical simulation for magnetic forces. The changes in resonance frequencies with magnetic fields reach a few percent, showing that an efficient magnetic control of resonance frequencies was achieved.
Fujita, Hiroki; Nojima, Takehiro; Nagaoka, Mika; Osawa, Takahito; Yokoyama, Hiroya; Ono, Hironobu*
KEK Proceedings 2016-8, p.168 - 172, 2016/10
An automatic analysis system was developed to analyze Strontium-90 (
Sr) radioactivity in environmental sample for 2013-2015. Various kinds of ashed environmental samples were used in performance tests of the automatic system. These tests were successful without any system trouble. However, Sr concentration had not been measured using the samples analyzed by the system. In this research, Sr concentration in seaweed sample was compared by between the system's analysis and worker's one. Moreover, the system was improved in each analysis process.
Nojima, Takehiro; Fujita, Hiroki; Nagaoka, Mika; Osawa, Takahito; Yokoyama, Hiroya; Ono, Hironobu*
KEK Proceedings 2015-4, p.111 - 115, 2015/11
Automatic strontium-90 analysis system was developed for environmental sample in this research. The system was successful to do wet ashing, chemical separation and ion exchange processes using robot, automatic heating system and so on. Hand-made control program can operate the system by itself.
Ono, Masao; Sueyoshi, Masanori*; Okayasu, Satoru; Hao, T.; Esaka, Fumitaka; Osawa, Takahito; Iguchi, Yusuke*; Mashimo, Tsutomu
Review of Scientific Instruments, 80(8), p.083908_1 - 083908_6, 2009/08
Times Cited Count：3 Percentile：17.78(Instruments & Instrumentation)A prototype rotor with 2 grooves for the multi-stage centrifugal isotope separation in solid state was developed to test a new idea. This idea is based on the sedimentation of constitutional atoms in solid. In the performance test using indium specimen, it is verified that the developed rotor can receive all injected molten-indium droplets from an automatic raw-material feeding system even at the high rotational speed of 97,000 r.p.m. without the loss of rotational stability, and the received indium specimens can be transferred in/between 2 grooves through the plastic flow under the influence of strong centrifugal force even in the solid state. The isotope ratio of centrifuged indium specimens was analyzed employing the Secondary Ion Mass Spectrometry (SIMS), and it is confirmed that intended isotope separation by the centrifugation is realized in the solid state.
Ono, Masao; Iguchi, Yusuke*; Okayasu, Satoru; Esaka, Fumitaka; Kobayashi, Katsura*; Hao, T.; Bagum, R.*; Osawa, Takahito; Fujii, Kimio; Nakamura, Eizo*; et al.
Defect and Diffusion Forum, 289-292, p.63 - 68, 2009/04
The atomic-scale graded structure of In-Pb alloy was formed by an ultracentrifuge experiment under conditions that a gravitational field of 0.81
10
G for 100 hours at 150 C in solid state in our previous study. The isotope ratio measurements were performed on the centrifuged sample with secondary ion mass spectrometer (SIMS). 
Pb/
Pb and 
Pb/Pb isotope ratio changed with negative gradient in the direction of centrifugal force approximately 1.5% and 0.8%, respectively. And three-isotope diagram of Pb/Pb versus Pb/Pb proved that the isotope fluctuation depends on isotopic mass difference. These results showed that the strong gravitational field not only affected on the inter-diffusion but also on self-diffusion in this alloy as causing isotope fractionation effect, and the isotope fractionation was dependent on mass-difference.
Osawa, Takahito; Ono, Masao; Esaka, Fumitaka; Okayasu, Satoru; Iguchi, Yusuke*; Hao, T.; Magara, Masaaki; Mashimo, Tsutomu
EPL; A Letters Journal Exploring the Frontiers of Physics, 85(6), p.64001_1 - 64001_5, 2009/03
Times Cited Count：6 Percentile：41.67(Physics, Multidisciplinary)Pure tin metals were centrifuged at 1
and at 220 C for 100 hours, 0.40 at 220-230 C for 24 hours, and 0.25 at 220 C for 24 hours. Their isotopic compositions were measured by a secondary ion mass spectrometer (SIMS). 
Sn/
Sn and 
Sn/Sn ratios of the 1.02 sample were considerably different than the initial compositions, and the magnitude of isotopic fractionation reached 2.6%. A three-isotope diagram of Sn/Sn versus Sn/Sn shows conclusively that isotopic fractionation caused by a gravitational field depended only on isotopic mass.
Ono, Masao; Iguchi, Yusuke*; Okayasu, Satoru; Esaka, Fumitaka; Kobayashi, Katsura*; Hao, T.; Bagum, R.*; Osawa, Takahito; Fujii, Kimio; Nakamura, Eizo*; et al.
Journal of Nuclear Science and Technology, 45(Suppl.6), p.108 - 110, 2008/09
Times Cited Count：1 Percentile：10.05(Nuclear Science & Technology)The atomic-scale graded structure of In-Pb alloy was formed by an ultracentrifuge experiment under conditions that a gravitational field of 810,000 G for 100 hours at 150C (solid state) in our previous study. The isotope fluctuation on this sample was measured using secondary ion mass spectrometer (SIMS). The ratio both Pb/Pb and 
In/
In changed with positive gradient in the direction of centrifugal force approximately 1.2%. These isotope fluctuations were larger than that of starting state of natural state (In
0.2%, Pb0.1%). These show that the sedimentation of isotopes occurred by solid centrifugation in this alloy, although achieved concentration gradients were small.
Ono, Masao; Iguchi, Yusuke*; Okayasu, Satoru; Esaka, Fumitaka; Kobayashi, Katsura*; Hao, T.; Bagum, R.*; Osawa, Takahito; Fujii, Kimio; Nakamura, Eizo*; et al.
no journal, ,
The atomic-scale graded structure of In-Pb alloy was formed by an ultracentrifuge experiment under conditions that a gravitational field of 0.8110G for 100 hours at 150 C in solid state in our previous study. The isotope ratio measurements were performed on the centrifuged sample with secondary ion mass spectrometer (SIMS, CAMECA IMS-6f). Both In/In and Pb/ isotope ratio changed with negative gradient in the direction of centrifugal force approximately 1.2% showing the tendency that the heavy In isotope (Pb isotope) abundance increased and light In isotope (Pb isotope) abundance decreased in the direction of centrifugal force. This showed that the isotope fractionation effect due to sedimentation of atoms occurred in this alloy by ultracentrifuge experiment.
Osawa, Takahito; Ono, Masao; Esaka, Fumitaka; Okayasu, Satoru; Iguchi, Yusuke*; Hao, T.; Mashimo, Tsutomu
no journal, ,
Pure tin metals were centrifuged at 1,0200,000G and at 220C for 100 hours, 400,000 G at 220-230C for 24 hours, and 250,000G at 220C for 24 hours. Their isotopic compositions were measured by a secondary ion mass spectrometer (SIMS). 116Sn/120Sn and 124Sn/120Sn ratios of the 1,0200,000G sample were considerably different than the initial compositions, and the magnitude of isotopic fractionation reached 2.6%. A three-isotope diagram of 116Sn/120Sn versus 124Sn/120Sn shows conclusively that isotopic fractionation caused by a gravitational field depended on isotopic mass.
Ono, Masao; Hao, T.; Okayasu, Satoru; Esaka, Fumitaka; Osawa, Takahito; Iguchi, Yusuke*; Mashimo, Tsutomu
no journal, ,
no abstracts in English
Osawa, Takahito; Ono, Masao; Esaka, Fumitaka; Okayasu, Satoru; Mashimo, Tsutomu*
no journal, ,
no abstracts in English
Osawa, Takahito; Nagao, Keisuke*; Ono, Masao
no journal, ,
Primordial trapped noble gas component in primitive chondrites is concentrated in phase Q. We tried to separate phase Q from a carbonaceous chondrite using ultra-centrifugation. Noble gases are concentrated in a heavy fraction, showing that phase Q may be heavy carbonaceous materials or heavy particles attached to carbonaceous materials.
Kawano, Yasunori; Imazawa, Ryota; Ono, Takehiro; Ishikawa, Masao; Hayashi, Toshimitsu; Sato, Kazuyoshi; Kusama, Yoshinori; Ebisawa, Katsuyuki*; Wakabayashi, Kuniaki*; Katsumata, Takahito*
no journal, ,
no abstracts in English
Osawa, Takahito; Ono, Masao; Esaka, Fumitaka; Okayasu, Satoru; Mashimo, Tsutomu*
no journal, ,
no abstracts in English
Nojima, Takehiro; Fujita, Hiroki; Nagaoka, Mika; Osawa, Takahito; Yokoyama, Hiroya; Ono, Hironobu*
no journal, ,
An automatic analysis system was developed to analyze radioactive strontium (Sr) radioactivity in environmental sample. The analysis method was followed to the manual compiled by the MEXT, to determine low level of Sr radioactivity concentration in environmental sample. In this research, the procedure of the Sr analysis before milking procedure of Y was automated except for a part of the analysis. The systems were controlled by an original program under the LabVIEW. Various kinds of ashed environmental samples were used in performance tests of the automatic system. These tests were successful without system trouble. Finally, Sr recovery was about 40-70% to whitebait analysis.
Ono, Masao; Okayasu, Satoru; Iguchi, Yusuke*; Esaka, Fumitaka; Ishitsuka, Etsuo; Osawa, Takahito; Ogata, Yudai; Mashimo, Tsutomu*
no journal, ,
Fujita, Hiroki; Nojima, Takehiro*; Nagaoka, Mika; Osawa, Takahito; Ono, Hironobu*
no journal, ,
no abstracts in English
