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Kimura, Nobuyuki; Hayashi, Kenji; Kamide, Hideki; Ito, Masami*; Sekine, Tadashi*
Nuclear Technology, 152(2), p.210 - 222, 2006/03
Times Cited Count：21 Percentile：77.20(Nuclear Science & Technology)An innovative sodium cooled fast reactor has been investigated on the feasibility study of FBR cycle system in Japan. A compact reactor vessel (R/V) and a column type upper inner structure (UIS) with a radial slit for an arm of a fuel-handling machine (FHM) are adopted. Dipped plates (D/P) are set in the R/V below the free surface to prevent gas entrainment. We performed an 1/10th scaled model water experiment for the upper plenum of the R/V. Gas entrainment was not observed in the experiment under the same velocity condition as the reactor. Three vortex cavitations were observed near the hot leg (H/L) inlet. A vertical rib on the R/V wall was found inlet to restrict the rotating flow near the H/L. The vortex cavitation between the R/V wall and the H/L was suppressed by the rib under the same cavitation factor condition as in the reactor. The cylindrical plug was installed through the hole in the D/P for FHM to reduce the flow toward the free surface. It was effective when the plug was submerged into the middle height in the upper plenum. This combination of two components had a possibility to optimize the flow in the compact R/V.
Nakayama, Oukatsu; Kimura, Nobuyuki; Kamide, Hideki; Ito, Masami*; Sekine, Tadashi*
JNC TN9400 2005-032, 103 Pages, 2005/03
JNC-TN9400-2005-032.pdf:33.44MB
On the FBR feasibility study, an innovative sodium cooled fast reactor has been investigated in Japan Nuclear Cycle Development Institute. In order to reduce the construction cost of reactor, the compact reactor vessel is designed. Gas entrainment at the free surface is one of issues to be solved because of high velocity in the upper plenum vessel. We performed an 1/10th scaled model water experiment for the upper plenum of reactor vessel and investigated flow fields in the plenum in order to optimize flow. In the last experiment, we established flow optimization structures for reduction of flow toward to the free surface and restraint on the vortex cavitations near H/L inlet, i.e., plug into the dipped plate hole to install a fuel handling mechanism (FHM) and a flow splitter at vessel wall. In this report, effects of double dipped plates (D/Ps) and outer shell of upper inner structure (UIS) are investigated. In the result, we could confirm that the double D/P structure set below the free surface is effective to reduce flow toward the free surface between reactor vessel wall and guide tube of fuel transfer machine. An FHM plug, which has a step structure at mid height between double D/Ps, showed that it reduced flow velocity through the gap between the plug and the D/P. A perforated outer shell was set around the UIS to reduce vortex strength developed from the cold legs to the hot leg intake and also to restrain the vortex cavitation. It was shown that the onset condition of vortex cavitation at reactor vessel wall was reduced and the cavitation occurred easily. At the cold leg the onset condition of the caviation was not advanced. The flow distribution through the perforated outer shell should be optimized.
Kimura, Nobuyuki; Hayashi, Kenji; Ito, Masami*; Sekine, Tadashi*; Igarashi, Minoru; Sato, Hiroyuki; Kamide, Hideki
JNC TN9400 2003-032, 214 Pages, 2003/03
JNC-TN9400-2003-032.pdf:111.0MB
An innovative sodium cooled fast reactor has been investigated on the FBR feasibility study. The design of the reactor is undergoing in order to reduce the construction cost of the reactor. For example, thermal output is increased against the reactor size and an upper inner structure (UIS) has a slit for the arm of the fuel-handling machine to simplify the fuel exchanging system. The dipped plates (D/P) are set below the free surface to prevent gas entrainment at free surface. We performed an 1/10th scaled model water experiment for the upper plenum of reactor vessel and investigated flow fields in the plenum in order to optimize flow. In the upper plenum, all of main components were set up as well as the reactor design. In addition, the D/P has a hole in front of the slit of the UIS to insert the fuel handling machine(FHM). As the experimental parameters, the core outlet velocity was varied from the condition of the Froude number similarity to the same value as the real reactor. The local velocity was measured by the particle image velocimetry and the ultrasound Doppler velocimetry. In the experimental results, gas entrainment at the free surface was not observed in the range from the Froude number similarity condition to the same velocity condition as the real reactor. However, the free surface was bulged on a large scale in front of the UIS slit. At the neighborhood of the H/L intake, three vortex cavitations were observed. The vortex cavitations were broken out under the same cavitation coefficient condition based on the H/L velocity as that in the real reactor. A vertical rib was set on the reactor vessel wall near the H/L inlet to restrict the rotating flow at the neighborhood of the H/L. As the result, the vortex cavitation at the region between the reactor vessel wall and the H/L was supressed under the same cavitation factor condition as the real reactor. A vertical cylinder, named FHM plug, was installed to close the hole in the D/P fbr FHM.
Kimura, Nobuyuki; Hayashi, Kenji; Igarashi, Minoru; Kamide, Hideki; Ito, Masami*; Sekine, Tadashi*
Proceedings of 10th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-10), CD-RO, K0102 Pages, 2003/00
An innovative sodium cooled fast reactor has been investigated on the feasibility study of FBR cycle system in JNC. A compact reactor vessel (R/V) and a column type upper inner structure (UIS) with a radial slit for an arm of a fuel-handling machine (FHM) are adopted. Dipped plates (D/P) are set in the R/V below the free surface to prevent gas entrainment at free surface. We performed an 1/10th scaled model water experiment for the upper plenum of the R/V. Gas entrainment at the free surface was not observed in the experiment under the same velocity condition as the designed reactor. However, the free surface rose in front of the UIS slit due to upward flow through the gap between the D/P and the R/V wall. The upward flow will cause free surface vortex and also the gas entrainment. Three vortex cavitations were observed near the hot leg (H/L) inlet. The vortex cavitations were broken out under the same cavitation factor condition as the reactor. A vertical rib was set on the R/V wall
; Onuki, Toshihiko; Isobe, Hiroshi; Yanase, Nobuyuki; Sekine, Keiichi; ;
Journal of Contaminant Hydrology, 35, p.191 - 199, 1998/00
Times Cited Count：4 Percentile：18.25(Environmental Sciences)no abstracts in English
Yanase, Nobuyuki; Sato, Tsutomu; ; Sekine, Keiichi
Radiochimica Acta, 82, p.319 - 325, 1998/00
no abstracts in English
Onuki, Toshihiko; Yanase, Nobuyuki; Sekine, Keiichi; Isobe, Hiroshi; Nagano, Tetsushi; Sakamoto, Yoshiaki
Journal of Nuclear Science and Technology, 34(12), p.1153 - 1158, 1997/12
Times Cited Count：27 Percentile：86.43(Nuclear Science & Technology)no abstracts in English
Yanase, Nobuyuki; Sato, Tsutomu; Isobe, Hiroshi; Sekine, Keiichi
Hoshasei Haikibutsu Kenkyu, 2(1-2), p.121 - 135, 1996/02
no abstracts in English
; Sato, Tsutomu; Nagano, Tetsushi; Yanase, Nobuyuki; Yamaguchi, Tetsuji; Isobe, Hiroshi; Onuki, Toshihiko; Sekine, Keiichi
JAERI-Review 95-011, 94 Pages, 1995/07
JAERI-Review-95-011.pdf:4.81MB
no abstracts in English
Yanase, Nobuyuki; T.E.Payne*; Sekine, Keiichi
Geochemical Journal, 29, p.31 - 54, 1995/00
Times Cited Count：25 Percentile：46.31(Geochemistry & Geophysics)no abstracts in English
Yanase, Nobuyuki; T.E.Payne*; Sekine, Keiichi
Geochemical Journal, 29, p.1 - 29, 1995/00
Times Cited Count：27 Percentile：49.78(Geochemistry & Geophysics)no abstracts in English
Yanase, Nobuyuki; Sekine, Keiichi
Materials Research Society Symposium Proceedings, Vol.353, 0, p.1235 - 1242, 1995/00
no abstracts in English
Yanase, Nobuyuki; Sekine, Keiichi
Nihon Genshiryoku Gakkai-Shi, 37(8), p.704 - 709, 1995/00
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)no abstracts in English
Yanase, Nobuyuki; Ueno, Takashi; Sekine, Keiichi; Kobayashi, Yoshii
Dai-34-Kai Kankyo Hoshano Chosa Kenkyu Seika Rombun Shorokushu; Heisei-3-Nendo, p.96 - 97, 1992/12
no abstracts in English
Onuki, Toshihiko; Murakami, Takashi; Sekine, Keiichi; Yanase, Nobuyuki; Isobe, Hiroshi; Kobayashi, Yoshii
Materials Research Society Symposium Proceedings, Vol. 176, p.607 - 614, 1990/00
no abstracts in English
Iwata, Hajime; Mitsui, Seiichiro; Sekine, Nobuyuki*
no journal, ,
In order to measure Fe-silicates precipitated under geological disposal conditions, a static leaching test has been conducted of simulated vitrified waste in 0.01 M FeCl
solution with a surface area to volume ratio = 10 m
at 90
C under a N
atmosphere. Obtained results indicate that Fe bearing minerals change from green rust to Fe-rich serpentine over time. Such mineral transitions are important as they may have an effect on the alteration behavior of glasses used for geological disposal of HLW.
Iwata, Hajime; Sekine, Nobuyuki*; Mitsui, Seiichiro
no journal, ,
Static leaching tests of simulated nuclear waste glass were carried out at 90C in an air atmosphere using a MgCl solution and deionized water. As a result, in the MgCl solution, temporal plateau and following resumption of glass dissolution were observed, while an ordinary dissolution behavior, which shows rate decrease with time, was observed in the deionized water. It is considered that these unique dissolution behavior in MgCl solution may be related to the evolution of the Mg-containing mineral species deposited on the glass surface.
Sato, Yuji; Takagi, Hisatsugu; Hamada, Nobuyuki; Sekine, Tomokazu*; Takeda, Masayuki*; Akiyama, Takashi*
no journal, ,
no abstracts in English
Matsubara, Ryuta*; Fujisaki, Kiyoshi*; Ishida, Keisuke*; Ishiguro, Katsuhiko*; Inagaki, Yaohiro*; Okubo, Takahiro*; Mitsui, Seiichiro; Iwata, Hajime; Sekine, Nobuyuki*
no journal, ,
Restriction of radionuclide release by low dissolution rate is expected for the vitrified waste as a one of safety functions of the geological disposal system. In order to assess the performance of vitrified waste, it is important to understand how its safety function works under the environmental condition of a deep geological repository. This presentation provides the recent progress on the R&D to improve the current understanding of the key processes affecting glass dissolution rate and the predictive modeling of long-term behavior of the vitrified waste.
Matsubara, Ryuta*; Fujisaki, Kiyoshi*; Ishida, Keisuke*; Ishiguro, Katsuhiko*; Inagaki, Yaohiro*; Okubo, Takahiro*; Mitsui, Seiichiro; Iwata, Hajime; Sekine, Nobuyuki*
no journal, ,
Since the performance of vitrified High-level Radioactive Waste depends on thermal, hydraulic, mechanical, and chemical (THMC) conditions, NUMO, as the implementer of geological disposal, has been promoting R&D of operational model the long-term performance of vitrified High-level Radioactive Waste in consideration of THMC conditions. NUMO has identified R&D issues regarding the glass dissolution and planed the R&D program through FEP (Features, Events, and Processes) analysis and parametric study with numerical model to evaluate relative importance of relevant processes. At present, three R&D programs are ongoing as joint researches with JAEA and two universities: long term glass dissolution experiment to understand evolution of glass dissolution kinetics, glass dissolution experiment at various environmental conditions to assess the performance under several potential repository conditions with the time evolution, and molecular dynamics simulation to understand elemental migration at the interface between glass surface and groundwater. The current status of R&D programs will be introduced in this presentation.
