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I in the contaminated water and tree samples at the Fukushima Daiichi Nuclear Power StationShimada, Asako; Ozawa, Mayumi; Kameo, Yutaka; Yasumatsu, Takuyo*; Nebashi, Koji*; Niiyama, Takuya; Seki, Shuhei; Kajio, Masatoshi; Takahashi, Kuniaki
Nuclear Back-end and Transmutation Technology for Waste Disposal, p.311 - 317, 2015/00
no abstracts in English
Tanaka, Kosuke; Miwa, Shuhei; Sato, Isamu; Hirosawa, Takashi; Sekine, Shinichi; Osaka, Masahiko; Obayashi, Hiroshi; Koyama, Shinichi
Journal of Nuclear Science and Technology, 51(7-8), p.876 - 885, 2014/07
Times Cited Count：5 Percentile：34.70(Nuclear Science & Technology)As a first step for obtaining experimental data on the effects of high-temperature chemical interaction on fission product (FP) release behavior, we focused on the dissolution of irradiated uranium plutonium mixed oxide (MOX) fuel by molten zircaloy (Zry), and carried out a heating test under the reducing atmosphere. Pieces of an irradiated MOX fuel pellet and cladding were subjected to the heating test at 2373 K for 5 min. The fractional release rate of cesium (specifically 
Cs) was monitored during the test and its release behavior was evaluated. The observation of microstructures and measurements of elemental distribution in the heated specimen were also performed. We demonstrated experimentally that the fuel dissolution by molten Zry accelerated the release of Cs from the fuel pellets.
Tanaka, Kosuke; Miwa, Shuhei; Sato, Isamu; Hirosawa, Takashi; Sekine, Shinichi; Seki, Takayuki*; Tokoro, Daishiro*; Obayashi, Hiroshi; Koyama, Shinichi
JAEA-Research 2013-022, 62 Pages, 2014/01
JAEA-Research-2013-022.pdf:33.64MB
In order to establish the method for heating tests focused on the fission product release resulting from the high temperature chemical interaction between fuel and cladding material and to obtain the novel data on fission product release behaviors, the heating test was carried out with irradiate MOX fuel pellet and cladding.
Tanaka, Kosuke; Miwa, Shuhei; Sekine, Shinichi; Yoshimochi, Hiroshi; Obayashi, Hiroshi; Koyama, Shinichi
Journal of Nuclear Materials, 440(1-3), p.480 - 488, 2013/09
Times Cited Count：13 Percentile：67.22(Materials Science, Multidisciplinary)In order to confirm the effect of minor actinide addition on irradiation behavior of MOX fuel pellets, 3% and 5% americium-containing MOX (Am-MOX) fuels were irradiated for 10 minutes at 43 kW/m and for 24 hours at 45 kW/m in the experimental fast reactor Joyo. Two nominal values of the fuel pellet oxygen-to-metal ratio (O/M), 1.95 and 1.98, were used as a test parameter. Emphasis was placed on the behavior of restructuring and redistribution of actinides which directly affect the fuel performance and the fuel design for fast reactors. Microstructural evolutions in the fuels were observed by optical microscopy and redistribution behavior of constituent elements was determined by mapping and quantitative point analyses of EPMA.
Osaka, Masahiko; Donomae, Takako; Ichikawa, Shoichi; Sasaki, Shinji; Ishimi, Akihiro; Inoue, Toshihiko; Sekio, Yoshihiro; Miwa, Shuhei; Onishi, Takashi; Asaka, Takeo; et al.
Proceedings of 1st Asian Nuclear Fuel Conference (ANFC), 2 Pages, 2012/03
Support system for training and education of future expert in hot laboratories of Oarai-JAEA, named FEETS, is presented. The system has been established based on research results on both characterization of Oarai hot laboratory and user-needs. Various programs under FEETS are also introduced.
Osaka, Masahiko; Konashi, Kenji*; Hayashi, Hirokazu; Li, D.*; Homma, Yoshiya*; Yamamura, Tomoo*; Sato, Isamu; Miwa, Shuhei; Sekimoto, Shun*; Kubota, Takumi*; et al.
Proceedings of International Conference on Toward and Over the Fukushima Daiichi Accident (GLOBAL 2011) (CD-ROM), 5 Pages, 2011/12
Summer schools for future experts have successfully been completed under Japan Actinide Network (J-ACTINET) for the purpose of development of human resources who are expected to be engaged in every areas of actinide-research/engineering. The first summer school was held in Ibaraki-area in August 2009, followed by the second one in Kansai-area in August 2010. Two summer schools have focused on actual experiences of actinides in actinide-research fields for university students and young researchers/engineers as an introductory course of actinide-researches. Several quasi actinide-handling experiences at the actinide-research fields have attracted attentions of participants at the first school in Ibaraki-area. The actual experiments using actinides-containing solutions have been carried out at the second school in Kansai-area. Future summer schools will be held every year for the sustainable human resource development in various actinide-research fields.
Miwa, Shuhei; Osaka, Masahiko; Yoshimochi, Hiroshi; Tanaka, Kenya; Seki, Takayuki*; Sekine, Shinichi*
JNC TN9400 2005-023, 43 Pages, 2005/04
JNC-TN9400-2005-023.pdf:3.56MB
The effect of oxygen potential on the sintering behavior of MOX fuel containing Am (Am-MOX) was investigated. Green pellets of Am-MOX were prepared by a conventional powder metallurgical technique. For Am-MOX fuel pellets sintered at various oxygen potential conditions, density measurement, microstructural observation and elements analyses by EPMA were performed High density pellets having good structure were obtained due to oxygen potential change of sintering atmosphere from high oxygen potential to low oxygen potential at 800
C in the cooling process.For the pellets sintered at -520 kJ/mol, -390 kJ/mol and -340 kJ/mol, the sintered density increases with increase of oxygen potential up to -390 kJ/mol (threshold oxygen potential), then decreases above the threshold oxygen potential. This tendency is similar to that observed in the (U,Gd)O
system. The differences of sintering behavior for Am-MOX pellets which were observed by changing the oxygen potential were attributable to the difference of pore structure, which was supposed to be caused by the valence state of Am in the oxides. On the other hands, the grain size of Am-MOX pellet sintered at -520 kJ/mol was almost the same as that at -390 kJ/mol. Homogeneous distribution of U, Pu and Am was obtained at pellets sintered both -520 and -390 kJ/mol in these sintering conditions. For the pellets sintered at 1500C , 1600C , 1700C , the high dense pellets are obtained, therefore This results shows the the possibility of fabrication of good fuel pellets at lower temperature than 1700C
Osaka, Masahiko; Miwa, Shuhei; Mondo, Kenji; Ozaki, Yoko; Ishi, Yohei; Yoshimochi, Hiroshi; Seki, Takayuki*; Sekine, Shinichi*; Ishida, Takashi*; Tanaka, Kenya
JNC TN9400 2005-002, 40 Pages, 2005/03
JNC-TN9400-2005-002.pdf:2.43MB
An experimental investigation for the phase relation of (U,Pu,Am)O was performed with XRD, ceramography and DTA. Although lattice parameter tended to increase with increases of Am content and O/M ratio, its slope differed from that of (U,Pu)O. A drastic structural change was observed around O/M=1.98. Besides, many DTA peaks, which could never be seen in the case of (U,Pu)O, were observed above O/M=1.98.These results were interpreted with a hypothesis that all Am were trivalent and equivalent amount of U became pentavalent. The dependence of lattice parameter on Am content could be expressed well by using a model with ionic radii of each element. Also the structural change around O/M=1.98 could be explained as caused by valence states of each element. It was concluded from these interpretation that all Am in (U,Pu,Am)O were likely to exist as trivalent state.
Tanaka, Kosuke; Miwa, Shuhei; Sato, Isamu; Hirosawa, Takashi; Obayashi, Hiroshi; Koyama, Shinichi; Yoshimochi, Hiroshi; Tanaka, Kenya; Sekine, Shinichi*
no journal, ,
Microstructural change was investigated on the Am-containing MOX fuel irradiated in JOYO for short term (24 hours).
Miwa, Shuhei; Osaka, Masahiko; Tanaka, Kosuke; Sekine, Shinichi*
no journal, ,
no abstracts in English
Hirosawa, Takashi; Sato, Isamu; Miwa, Shuhei; Ishida, Takashi*; Sekine, Shinichi*
no journal, ,
no abstracts in English
Onishi, Takashi; Osaka, Masahiko; Miwa, Shuhei; Obayashi, Hiroshi; Sekino, Hirotaka*; Kirishima, Akira*; Sato, Nobuaki*
no journal, ,
As a demonstration of nuclear fuel reprocessing by sulfurization reaction, voloxidation, selective sulfurization and selective dissolution of simulated spent nuclear fuel pellet fabricated from U, Pu, Am and non-radioactive FP were conducted. As results, dissolution rate of each elements were obtained and behavior of MA and FP were investigated.
Osaka, Masahiko; Miwa, Shuhei; Tanaka, Kosuke; Sekine, Shinichi*
no journal, ,
Basic sintering tests of UO
/PuO-Mo cermet were carried out adding Ni and Pd as sintering additives. Optimal conditions to achieve high density cermet were pursured. This study intends to obtain basic knowledge about densification of Mo-cermet when metal impurities are included.
Tanaka, Kosuke; Miwa, Shuhei; Sato, Isamu; Hirosawa, Takashi; Obayashi, Hiroshi; Koyama, Shinichi; Yoshimochi, Hiroshi; Tanaka, Kenya; Sekine, Shinichi*
no journal, ,
Am redistribution behavior was investigated on the Am-containing MOX fuel irradiated for short term in JOYO.
Tanaka, Kosuke; Miwa, Shuhei; Sato, Isamu; Hirosawa, Takashi; Obayashi, Hiroshi; Koyama, Shinichi; Yoshimochi, Hiroshi; Tanaka, Kenya; Sekine, Shinichi*
no journal, ,
Am redistribution behavior was investigated on the Am-containing MOX fuel irradiated for short term in Joyo.
Tanaka, Kosuke; Miwa, Shuhei; Sato, Isamu; Hirosawa, Takashi; Obayashi, Hiroshi; Koyama, Shinichi; Yoshimochi, Hiroshi; Tanaka, Kenya; Sekine, Shinichi*
no journal, ,
Effect of O/M ratio on the Am redistribution was investigated on the Am-containing MOX fuel irradiated for short term in Joyo.
Asaka, Takeo; Osaka, Masahiko; Donomae, Takako; Ichikawa, Shoichi; Sasaki, Shinji; Ishimi, Akihiro; Inoue, Toshihiko; Sekio, Yoshihiro; Miwa, Shuhei; Onishi, Takashi; et al.
no journal, ,
Activities on a system development for education and training of future experts in the nuclear field thorough experiments at PIE facilities are given. Basic concept of the system and acceptance-support apparatus are introduced.
Sato, Isamu; Hirosawa, Takashi; Miwa, Shuhei; Suto, Mitsuo; Sekine, Shinichi; Seino, Hiroshi; Ohno, Shuji
no journal, ,
Migration behavior of radioactive materials such as Pu and Am from irradiated U-Pu mixed oxide fuels were evaluated by analyzing sampling parts with EPMA, 
-ray and 
-ray spectrometries.
Tanaka, Kosuke; Miwa, Shuhei; Sato, Isamu; Hirosawa, Takashi; Sekine, Shinichi; Obayashi, Hiroshi; Koyama, Shinichi; Seki, Takayuki*; Tokoro, Daishiro*
no journal, ,
In order to develop the heating method for both fuel pellet and cladding, irradiated MOX fuel together with Zry-2 cladding were heated by using source term evaluation equipment.
Sato, Isamu; Hirosawa, Takashi; Miwa, Shuhei; Tanaka, Kosuke; Koyama, Shinichi; Tokoro, Daishiro*; Seki, Takayuki*
no journal, ,
Fuel pellets irradiated in the advanced thermal reactor, "FUGEN", were heated using a high frequency induction fuenace, and then the release and residue behavior of fission products were observed.
