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Ishimi, Akihiro; Katsuyama, Kozo; Nakamura, Hirofumi; Asaka, Takeo; Furuya, Hirotaka
Nuclear Technology, 189(3), p.312 - 317, 2015/03
Times Cited Count：4 Percentile：33.25(Nuclear Science & Technology)A high resolution X-ray CT technique was developed, which made it possible to obtain fine X-ray CT images of an irradiated fuel assembly. In addition, the density distributions in the irradiated MOX fuel pellet could be continually measured, using the relationship between the densities and CT values. These results were compared to the one obtained by metallographical method. As results, it was found that the relative change of radial density distributions in the irradiated fuel pellet can be measured more accurately by the X-ray CT technique than by the metallographical examination.
Inoue, Masaki; Asaka, Takeo
JAEA-Review 2014-020, 46 Pages, 2014/06
JAEA-Review-2014-020.pdf:5.81MB
Integrity of fuel assemblies (FAs) stored in the spent fuel pools (SFPs) of Fukushima Dai-ichi Nuclear Power Station (units 1 through 4) is one of the most important issues to transport the FAs to the common pool for long term storage. The SFPs had lost their functions of decay heat removal and water supply due to the station blackout. Since fresh and sea waters were injected into and concrete fragments by hydrogen explosions fell into the SFPs, the FAs have been exposed to much more corrosive environments than usual ones. In this report, many events during the accidents were investigated from a view point of temperature and chemical constituents in the SFPs in order to evaluate integrity for fuel assemblies during long term storage in the common pool by means of corrosion tests.
Ishimi, Akihiro; Katsuyama, Kozo; Maeda, Koji; Nagamine, Tsuyoshi; Asaka, Takeo; Furuya, Hirotaka
Journal of Nuclear Science and Technology, 49(12), p.1144 - 1155, 2012/12
Times Cited Count：8 Percentile：52.49(Nuclear Science & Technology)no abstracts in English
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.
Inoue, Toshihiko; Yamagata, Ichiro; Asaka, Takeo
Nihon Genshiryoku Gakkai-Shi ATOMO
, 53(9), p.638 - 642, 2011/09
This paper presents the properties and the development of modified 316 steel. The core material is required to high-temperature strength caused by high power density and FP gas, swelling resistance caused by irradiation damage, and corrosion resistance caused by coolant sodium and FCCI. In the improvement of the modified 316 stainless steel, screening test conducted to improve high-temperature strength and swelling resistance. Optimizing a slight amount of addition element and cold working, the modified 316 steel was improved the high-temperature strength and swelling resistance in both. And under irradiated and FCCI conditions, these properties were tested. The modified 316 stainless steel uses 44,000 pins as fast reactor fuel pin in JOYO. These results show that the steel exhibits excellent characteristics in creep rupture strength and swelling resistance.
Katsuyama, Kozo; Ishimi, Akihiro; Nagamine, Tsuyoshi; Asaka, Takeo
Kensa Gijutsu, 16(2), p.12 - 18, 2011/02
no abstracts in English
Tanaka, Kosuke; Kawamata, Kazuo; Yoshimochi, Hiroshi; Sozawa, Shizuo; Onose, Shoji; Niimi, Motoji; Asaka, Takeo
Proceedings of 1st Asian Symposium on Material Testing Reactors (ASMTR 2011), p.71 - 76, 2011/02
Post irradiation examination (PIE) facilities have been operated for about 40 years at the Oarai Research and Development Center of the Japan Atomic Energy Agency to investigate the performance and soundness of irradiated fuels and materials. The JMTR Hot Laboratory (JMTR-HL) was founded in 1971 mainly to examine the objects irradiated in the Japan Material Testing Reactor (JMTR). The Alpha-Gamma Facility (AGF) was constructed as the first laboratory to perform PIE of plutonium-bearing fuels for Japanese fast reactor development programs. This facility started hot operation in 1971 and has performed physical, metallurgical, and chemical examinations of irradiated fuels including uranium plutonium mixed oxide fuels. A renewal plan for the JMTR-HL and AGF is now in progress, associated with re-operation of the JMTR.
Katsuyama, Kozo; Ishimi, Akihiro; Nagamine, Tsuyoshi; Asaka, Takeo
Proceedings of 47th Annual Meeting of the Working Group "Hot Laboratories and Remote Handling" (HOTLAB 2010) (CD-ROM), 4 Pages, 2010/09
In order to observe the structural change in the interior of irradiated fuel assembly, the non-destructive post irradiation examination technique using X-ray computer tomography (X-ray CT) was developed. In this X-ray CT system, the 12 MeV X-ray pulse was used in synchronization with the switch-in of the detector to minimize the effects of the 
ray emissions from the irradiated fuel assembly. In this study, this X-ray CT technique was upgraded for observing the inner condition of the fuel pellet using the high resolution X-ray CT image. In this paper, we describe following two items; (1) Development of high resolution X-ray CT technique, and (2) Result of high resolution X-ray CT image of an irradiated fuel pellet.
Katsuyama, Kozo; Ishimi, Akihiro; Maeda, Koji; Nagamine, Tsuyoshi; Asaka, Takeo
Journal of Nuclear Materials, 401(1-3), p.86 - 90, 2010/06
Times Cited Count：4 Percentile：30.63(Materials Science, Multidisciplinary)The helium releases were investigated in FBR fuel pins irradiated to high burn-up. The released amounts of helium gas increased with the increase of burn-up, but their data were scattered in the region of high burn-up region. This was understood to be caused by the differences of 
Am contents among fuel pellets, because this nuclide generates 
Cm which undergoes alpha decay at a short half life.
Tanaka, Kenya; Ishii, Tetsuya; Yoshimochi, Hiroshi; Asaka, Takeo
Proceedings of International Conference on Advanced Nuclear Fuel Cycle; Sustainable Options & Industrial Perspectives (Global 2009) (CD-ROM), p.2045 - 2050, 2009/09
As a part of the economic evaluation of the MA recycling system, the management cost of high level radioactive waste was estimated quantitatively. The development of an innovative fuel fabrication process has been done by using UO
powder, U metal particles and Mo powder. From comparisons of granulated material characteristics, two candidate methods, mixing granulation (MIX/G) and extruding granulation (EXT/G), were considered to have good feasibility as the fuel fabrication process. In the preliminary sintering test of granulated UO obtained by EXT/G, a high density UO pellet (97% of TD) with 5wt% of U and 5wt% of Mo was successfully sintered. From the results of thermal conductivity measurements, it was confirmed that the dispersion of Mo powder and U metal into the oxide matrix was an effective way to improve the characteristic.
Ishii, Tetsuya; Nemoto, Junichi*; Asaka, Takeo; Sato, Seichi*; Mayorshin, A.*; Shishalov, O.*; Kryukov, F.*
Journal of Nuclear Science and Technology, 45(4), p.263 - 273, 2008/04
Times Cited Count：2 Percentile：16.99(Nuclear Science & Technology)In order to develop a vibro-packed MOX fuel performance analysis code, thermochemical and mechanical properties of the vibro-packed fuels were incorporated into a pellet type fuel performance analysis code CEDAR. Calculations were made by the developed code on a vibro-packed MOX fuel pin irradiated at BN-600 in Russia. Since the calculated results agreed well with the behaviors obtained from the experimental data, it can be concluded that the code was well modeled and qualitatively validated.
Katsuyama, Kozo; Nagamine, Tsuyoshi; Nakamura, Yasuo; Asaka, Takeo; Furuya, Hirotaka
Transactions of the American Nuclear Society, 97(1), p.620 - 621, 2007/11
no abstracts in English
Katsuyama, Kozo; Nagamine, Tsuyoshi; Nakamura, Yasuo; Matsumoto, Shinichiro; Asaka, Takeo; Furuya, Hirotaka
Transactions of the American Nuclear Society, 94(1), p.771 - 772, 2006/06
no abstracts in English
Katsuyama, Kozo; Nagamine, Tsuyoshi; Matsumoto, Shinichiro; Asaka, Takeo; Ito, Masahiko; Furuya, Hirotaka
2004 ANS Winter Meeting, 91, 0 Pages, 2004/00
Non-destructive X-ray computed tomography (X-ray CT scanning) is a powerful technique for characterizing the morphology in structural materials as used in medical field. This X-ray CT scanning technique was developed for the purpose of post irradiation examinations (PIE), and applied to the fuel assemblies irradiated in the experimental fast reactor Joyo.
Maeda, Koji;
Journal of Nuclear Materials, 327(1), 0 Pages, 2004/00
None
Inoue, Masaki*; Iwai, Takashi; Arai, Yasuo; Asaga, Takeo*
Proceedings of GLOBAL2003 Atoms for Prosperity; Updating Eisenhower's Global Vision for Nuclear Energy (CD-ROM), p.1694 - 1703, 2003/11
no abstracts in English
; Iwai, Takashi*; Arai, Yasuo*; Asaka, Takeo
Global 2003; International Conference on Atoms for Prosperity: Upda, 1694 Pages, 2003/00
Under the collaboration between JNC and JAERI, two uranium-plutonium mixed nitride fuel pins, whose smear densities were varied by fuel-to-cladding gap sizes, were irradiated in the experimental fast reactor JOYO. Linear heat rate, cladding mid-wall temperature, and burnup in peak were 75 kW/m, 906K, and 4.3 %FIMA, respectively. In order to evaluate nitride fuels for high burnup capability, the effect of fuel swelling behavior on irradiation performance was investigated. The larger smear density induced the greater cladding diameter increments. The wider gap size resulted in the more anisotropic deformations. Threshold temperature of fuel swelling was studied by thermal analysis using radial porosity and xenon retention profiles. To attain higher burnup, experimental results indicate that maximum fuel temperatures should be preferably lower than threshold temperatures of fuel swelling and that the detrimental effects of fuel pellet relocations need to be suppressed and accommodated.
Uwaba, Tomoyuki; ;
JNC TN9400 2002-002, 49 Pages, 2002/03
JNC-TN9400-2002-002.pdf:1.34MB
Bundle Duct Interaction (BDI) is one of the life limiting factors of a FBR fuel subassembly. Under the BDl condition, the fuel pin dispersion. would occur mainly by the deviation of the wire position due to the irradiation. In this study the effect of the dispersion on the bundle deformation was evaluated by using the BAMBOO code and following results were obtained. (1)A new contact analysis model was introduced in BAMBOO code. This model considers the contact condition at the axial position other than the modal point of the beam element that composes the fuel pin. This improvement made it possible in the bundle deformation analysis to cause fuel pin dispersjon due to the deviations of the wire position. (2)This model was validated with the results of the out-of-pile compression test with the wire deviation. The calculated pin-to-duct and pin-to-pin clearances with the dispersion model almost agreed with the test results. Therefore it was confirmed that the BAMBOO code reasonably predicts the bundle deformation with the dispersion. (3)In the dispersion bundle the pin-to-pin clearanees widely scattered. And the minimum pin-to-duct clearance increased or decreased depending on the dispersion condition compared to the no-dispersion bundle. This result suggests the possibility that the considerable dispersion would affect the thermal integrity of the bundle.
Inoue, Masaki; ; ; ; Sekine, Takashi; Osaka, Masahiko
Journal of Nuclear Materials, 323(1), p.108 - 122, 2002/00
Times Cited Count：10 Percentile：56.43(Materials Science, Multidisciplinary)None
