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Shibata, Taiju; Mizuta, Naoki; Sumita, Junya; Sakaba, Nariaki; Osaki, Takashi*; Kato, Hideki*; Izawa, Shoichi*; Muto, Takenori*; Gizatulin, S.*; Shaimerdenov, A.*; et al.
Proceedings of 9th International Topical Meeting on High Temperature Reactor Technology (HTR 2018) (USB Flash Drive), 7 Pages, 2018/10
Graphite materials are used for the in-core components of High Temperature Gas-cooled Reactor (HTGR). Oxidation damage on the graphite components in air ingress accident is a crucial issue for the safety point of view. SiC coating on graphite surface is a possible technique to enhance oxidation resistance. However, it is important to confirm the integrity of this material against high temperature and neutron irradiation for the application of the in-core components. JAEA and Japanese graphite companies carried out the R&D to develop the oxidation-resistant graphite. JAEA and INP investigated the irradiation effects on the oxidation-resistant graphite by using a framework of ISTC partner project. This paper describes the results of post irradiation experiment about the neutron irradiated SiC-coated oxidation-resistant graphite. A brand of oxidation-resistant graphite shows excellent performance against oxidation test after the irradiation.
Mizuta, Naoki; Sumita, Junya; Shibata, Taiju; Osaki, Takashi*; Kato, Hideki*; Izawa, Shoichi*; Muto, Takenori*; Gizatulin, S.*; Sakaba, Nariaki
Tanso Zairyo Kagaku No Shinten; Nihon Gakutsu Shinkokai Dai-117-Iinkai 70-Shunen Kinen-Shi, p.161 - 166, 2018/10
To enhance oxidation resistance of graphite material for in-core components of HTGR, JAEA and four Japanese graphite companies; Toyo Tanso, IBIDEN, Tokai Carbon and Nippon Techno-Carbon, are carrying out for development of oxidation-resistant graphite by CVD-SiC coating. This paper describes the outline of neutron irradiation test about the oxidation-resistant graphite by WWR-K reactor of INP, Kazakhstan through an ISTC partner project. Prior to the irradiation test, the oxidation-resistant graphite by CVD-SiC coating of all specimens showed enough oxidation resistance under un-irradiation condition. The neutron irradiation test was already completed and out-of-pile oxidation test will be carried out at the hot-laboratory of WWR-K.
Shibata, Taiju; Sumita, Junya; Sakaba, Nariaki; Osaki, Takashi*; Kato, Hideki*; Izawa, Shoichi*; Muto, Takenori*; Gizatulin, S.*; Shaimerdenov, A.*; Dyussambayev, D.*; et al.
Proceedings of 8th International Topical Meeting on High Temperature Reactor Technology (HTR 2016) (CD-ROM), p.567 - 571, 2016/11
Graphite are used for the in-core components of HTGR, and it is desirable to enhance oxidation resistance to keep much safety margin. SiC coating is the candidate method for this purpose. JAEA and four Japanese graphite companies are studying to develop oxidation-resistant graphite. Neutron irradiation test was carried out by WWR-K reactor of INP of Kazakhstan through ISTC partner project. The total irradiation cycles of WWR-K operation was 10 cycles by 200 days. Irradiation temperature about 1473 K would be attained. The maximum fast neutron fluence (E 
0.18 MeV) for the capsule irradiated at a central irradiation hole was preliminary calculated as 1.2
10
/m
, and for the capsule at a peripheral irradiation hole as 4.210
/m. Dimension and weight of the irradiated specimens were measured, and outer surface of the specimens were observed by optical microscope. For the irradiated oxidation resistant graphite, out-of-pile oxidation test will be carried out at an experimental laboratory.
Tanaka, Kosuke; Sato, Isamu; Hirosawa, Takashi; Kurosaki, Ken*; Muta, Hiroaki*; Yamanaka, Shinsuke*
Journal of Nuclear Science and Technology, 52(10), p.1285 - 1289, 2015/10
Times Cited Count：2 Percentile：18.97(Nuclear Science & Technology)Polycrystalline specimens of americium-containing barium plutonate have been prepared by mixing the appropriate amounts of (Pu
Am
)O
and BaCO
powders followed by reacting and sintering at 1600 K under the flowing gas atmosphere of dry-air. The sintered specimens had a single phase of orthorhombic perovskite structure and were crack-free. The elastic moduli were determined from the longitudinal and shear sound velocities. The Debye temperature was also determined from the sound velocities and lattice parameter measurements. The thermal conductivity was calculated from the measured density at room temperature, literature values of heat capacity, and thermal diffusivity measured by laser flash method in vacuum. The thermal conductivity of americium-containing barium plutonate was roughly independent of the temperature and was almost the same magnitude as that of BaPuO and BaUO.
Osaki, Hirotaka; Shimazaki, Yosuke; Sumita, Junya; Shibata, Taiju; Konishi, Takashi; Ishihara, Masahiro
Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 8 Pages, 2015/05
For the design on the VHTR graphite components, it is desirable to employ graphite material with higher strength. IG-430 graphite has been developed as an advanced candidate for VHTR. However, the new developed IG-430 does not have enough databases for the design of HTGR. In this paper, the compressive strength (Cs) of IG-430, one of important strengths for design data, is statistically evaluated. The component reliability is evaluated based on the safety factors defined by the graphite design code, and the applicability as the VHTR graphite material is discussed. It was found that IG-430 has higher strength (about 11%) and lower standard deviation (about 27%) than IG-110 which is one of traditional graphites used for HTGR, because the crack in IG-430 would not easy to propagate rather than IG-110. Since fracture probability for IG-430 is low, the higher reliability of core-component will be achieved using IG-430. It is expected that IG-430 is applicable for VHTR graphite material.
Fujita, Ichiro*; Eto, Motokuni*; Osaki, Hirotaka; Shibata, Taiju; Sumita, Junya; Konishi, Takashi; Yamaji, Masatoshi; Kunimoto, Eiji
JAEA-Research 2013-004, 20 Pages, 2013/07
JAEA-Research-2013-004.pdf:2.4MB
Graphite components in HTGR and VHTR may be oxidized by impurities in coolant helium-gas even at normal operation, as well as by air at air-ingress accident. In this study, by air-oxidation test at 520-900
C, oxidation characteristics of IG-110 and IG-430 graphites, and associated decrease in compressive strength were examined. The following results were obtained. (1) The activation energy of the air-oxidation for IG-430 is 176 kJ/mol being almost same as for IG-110, though the oxidation rate for IG-430 is less than a half of that for IG-110. (2) There are correlations between density change and decrease in compressive strength. Decrease in strength is the largest in case that the oxidation temperature is lower than 600 C where the homogenous oxidation occurs. (3) In the process of oxidation, amorphous binder regions are predominantly oxidized. It suggests that peeling-off of cokes grains is necessary to be considered for oxidation weight loss, as well as gasification.
Tanaka, Kosuke; Sato, Isamu; Hirosawa, Takashi; Kurosaki, Ken*; Muta, Hiroaki*; Yamanaka, Shinsuke*
Journal of Nuclear Materials, 422(1-3), p.163 - 166, 2012/03
Times Cited Count：8 Percentile：54.4(Materials Science, Multidisciplinary)Polycrystalline specimens of strontium plutonate, SrPuO, have been prepared by mixing the appropriate amounts of PuO and SrCO powders followed by reacting and sintering at 1600 K under the flowing gas atmosphere of dry-air. The sintered specimens had a single phase of orthorhombic perovskite structure and were crack-free. The elastic moduli of SrPuO were determined from the longitudinal and shear sound velocities. The Debye temperature was also determined from the sound velocities and lattice parameter measurements. The thermal conductivity of SrPuO was calculated from the measured density at room temperature, literature values of heat capacity, and thermal diffusivity measured by laser flash method in vacuum.
Tanaka, Kosuke; Osaka, Masahiko; Miwa, Shuhei; Hirosawa, Takashi; Kurosaki, Ken*; Muta, Hiroaki*; Uno, Masayoshi*; Yamanaka, Shinsuke*
Journal of Nuclear Materials, 420(1-3), p.207 - 212, 2012/01
Times Cited Count：6 Percentile：45.12(Materials Science, Multidisciplinary)In order to investigate the effect on fuel thermophysical properties when adding americium and selected fission products to uranium-plutonium mixed fuel, simulated low decontamination MOX fuel with high burn-ups to 250 GWd/t, has been prepared and subjected to characterization tests, elastic moduli measurements, melting temperature measurement.
Ge spectrometerHarada, Hideo; Goko, Shinji*; Kimura, Atsushi; Ota, Masayuki*; Oshima, Masumi; Kitatani, Fumito; Toh, Yosuke; Furutaka, Kazuyoshi; Kin, Tadahiro; Koizumi, Mitsuo; et al.
Journal of the Korean Physical Society, 59(2), p.1547 - 1552, 2011/08
Times Cited Count：8 Percentile：51.69(Physics, Multidisciplinary)For the improvement of the accuracy on the neutron capture cross sections, a 4 Ge spectrometer was developed. The 4 Ge spectrometer is a unique tool due to its superior energy resolution for studying properties on neutron capture reactions, not only capture cross sections but also resonance identification, 
-ray intensity distribution, and spin-parity assignment. For example, its performance on the resonance identification was demonstrated using a 
Ag sample. On the measurement of a -ray intensity distribution for each resonance, the results of 
U will be shown. Using the 4 Ge spectrometer, the measurements of neutron capture cross sections were started at the J-PARC/MLF/ANNRI. The preliminary results on the measurements of neutron capture cross sections will be discussed mainly based on measurements of neutron capture cross sections for 
Am, together with related techniques.
at temperatures from 300 to 1500 KTanaka, Kosuke; Sato, Isamu; Hirosawa, Takashi; Kurosaki, Ken*; Muta, Hiroaki*; Yamanaka, Shinsuke*
Journal of Nuclear Materials, 414(2), p.316 - 319, 2011/07
Times Cited Count：22 Percentile：84.91(Materials Science, Multidisciplinary)Polycrystalline specimens of barium plutonate, BaPuO, have been prepared by mixing the appropriate amounts of PuO and BaCO followed by reacting and sintering at 1600 K under the flowing gas atmosphere of dry-air. The thermal conductivity of BaPuO was almost the same magnitude as that of BaUO.
Kadono, Atsunobu; Funakawa, Shinya*; Kosaki, Takashi*
Soil Science and Plant Nutrition, 55(2), p.243 - 251, 2009/04
Times Cited Count：9 Percentile：28.47(Plant Sciences)To understand the dynamics of soil organic matter (SOM) in humid Asia, several properties were tested to estimate the amounts of potentially mineralizable carbon (PMC) and nitrogen (PMN) as well as recalcitrant carbon (ROC) and nitrogen (RON). Eighty-nine surface soil samples were collected in Thailand, Indonesia and Japan from cropland and forest ecosystems. The fresh soils were incubated under constant conditions, and the CO and the mineral N from the soils were monitored. PMC and PMN were determined by fitting models to the cumulative curves of the emitted C and N. ROC and RON were determined by the subtraction of PMC and PMN from TC and TN, respectively. Using multiple regression analysis with the stepwise method, PMC and PMN was well estimated by carbon and nitrogen content of light fraction (LFC and LFN) and clay content, while ROC and RON were estimated by LF-OM, amorphous materials and clay content, suggesting the importance of parent materials in this region.
Osaka, Masahiko; Namekawa, Takashi; Kurosaki, Ken*; Yamanaka, Shinsuke*
Journal of Nuclear Materials, 344(1-3), p.230 - 234, 2005/09
Times Cited Count：12 Percentile：63.79(Materials Science, Multidisciplinary)The oxygen potential isotherms of (U,Pu,Am)O were represented by a chemical thermodynamic model proposed by Lindemer et al. It was assumed in the present model that (U,Pu,Am)O consisted of the chemical species PuO, Pu
O, AmO, Am
O and UO in a pseudo-quaternary system by treating the reduction rates of Pu and Am as identical; furthermore an interaction between AmO and UO was introduced. The agreement between analytical and experimental isotherms was good, but the analytical values slightly overestimated the experimental values especially in the case of lower Am content. Adding an interaction between AmO and PuO to the model resulted in a better representation.
,Pu
,Am
)O solid solutionsOsaka, Masahiko; Sato, Isamu; Namekawa, Takashi; Kurosaki, Ken*; Yamanaka, Shinsuke*
Journal of Alloys and Compounds, 397(1-2), p.110 - 114, 2005/07
Times Cited Count：25 Percentile：78.86(Chemistry, Physical)Oxygen potentials of (U,Pu)O containing AmO, (UPuAm)O, were measured as functions of the oxygen to metal (O/M) ratios and temperatures by hermogravimetric analysis (TGA) and discussed from thermodynamic viewpoints. The (UPuAm)O solid solution was prepared by a traditional powder metallurgical route. Oxygen partial pressure (pO) was adjusted in the region from 10
to 10
MPa by using CO/H and HO /H equilibria. Changes of microgram order in the specimen weight were continuously monitored with a TGA apparatus and the dependences of oxygen potentials on the O/M ratios were obtained at 1123K, 1273K and 1423K. The oxygen potentials of (UPuAm)O were significantly higher than those in (U
Pu
)O. The partial molar entropy and enthalpy of oxygen have been calculated and compared with those of Am O, (Am
U) O, and (UPu)O. Finally, the oxygen potential isotherms of (U,Pu,Am)O were examined in terms of defect structure.
Yamanaka, Shinsuke*; Uno, Masayoshi*; Kurosaki, Ken*; Osaka, Masahiko; Sato, Isamu; Namekawa, Takashi; Kato, Masato; Kihara, Yoshiyuki
JNC TY9400 2004-001, 111 Pages, 2004/04
JNC-TY9400-2004-001.pdf:2.81MB
As the fundamental study for MOX containing MA fuel, property measurement and its evaluation has been performed by JNC and Osaka university, respectively. Each results were compared, and the properties of MOX containing MA has been evaluated totally.
Hamada, Kazuya; Nakajima, Hideo; Okuno, Kiyoshi; Endo, Sakaru*; Kikuchi, Kenichi*; Kubo, Yoshio*; Aoki, Nobuo*; Yamada, Yuichi*; Osaki, Osamu*; Sasaki, Takashi*; et al.
JAERI-Tech 2002-027, 23 Pages, 2002/03
JAERI-Tech-2002-027.pdf:2.94MB
The Engineering Design Activities (EDA) for the International Thermonuclear Experimental Reactor (ITER) was performed under the collaboration of Japan, EU, Russia and the US. The EDA was successfully completed in July 2001, in which the development of fabrication technology for advanced components, such as superconducting coils, was conducted. The ITER magnet system consists of Toroidal Field coils, a Central Solenoid (CS), Poloidal Field coils and Correction coils. The construction of these coils requires advanced technologies that fairly exceeded those available at the start of the EDA. Therefore, CS Model Coil and TF Model Coil projects were implemented. To fabricate the CS Model Coil, the fabrication technologies for high performance strand, large cable, winding, heat treatment, joint and insulation are indispensable. This report describes the above detailed fabrication technologies successfully developed in the CS Model Coil Project.
Yamanaka, Shinsuke*; Uno, Masayoshi*; Kurosaki, Ken*; ; Namekawa, Takashi
JNC TY9400 2001-004, 175 Pages, 2001/03
no abstracts in English
Yamanaka, Shinsuke*; Uno, Masayoshi*; Kurosaki, Ken*; ; Namekawa, Takashi
JNC TY9400 2000-011, 41 Pages, 2000/03
JNC-TY9400-2000-011.pdf:1.28MB
no abstracts in English
Ando, Toshinari; Hiyama, Tadao; Takahashi, Yoshikazu; Nakajima, Hideo; Kato, Takashi; Isono, Takaaki; Sugimoto, Makoto; Kawano, Katsumi; Koizumi, Norikiyo; Nunoya, Yoshihiko; et al.
IEEE Transactions on Applied Superconductivity, 10(1), p.568 - 571, 2000/03
Times Cited Count：10 Percentile：53.86(Engineering, Electrical & Electronic)no abstracts in English
Ando, Toshinari; Hiyama, Tadao; Takahashi, Yoshikazu; Nakajima, Hideo; Kato, Takashi; Sugimoto, Makoto; Isono, Takaaki; Kawano, Katsumi; Koizumi, Norikiyo; Hamada, Kazuya; et al.
IEEE Transactions on Applied Superconductivity, 9(2), p.628 - 631, 1999/06
Times Cited Count：8 Percentile：51.78(Engineering, Electrical & Electronic)no abstracts in English
Kadono, Atsunobu; Funakawa, Shinya*; Kosaki, Takashi*
no journal, ,
For better understanding of the terrestrial SOM dynamics and its modelling, following studies were conducted: (1) to determine the factors that affect the amounts of labile and recalcitrant SOM in different ecosystems, and (2) to offer a simple process-based model with measurable SOM pools that describe in situ SOM dynamics in natural grassland ecosystems. According to the relationship between potentially mineralizable C (PMC) and soil properties in forty-one surface soils collected in Ukraine and Kazakhstan, a SOM dynamics model was constructed using parameters including the PMC, net primary productivity (NPP) and soil respiration on a daily time. Measured soil respiration in Ukraine from 2002 to 2004 was well estimated by the SOM model. These results suggested that the proposed model successfully simulated the decomposition processes of PMC in natural grassland ecosystems.
