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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：79.04(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
Sato, Hiroyuki; Kobayashi, Jun; Kamide, Hideki; Sekine, Tadashi*
no journal, ,
The fuel bundle in the high burn-up reactor core has the possibility of deformation by the swelling and the thermal bow and the heat removal performance will decline. In this report, the fuel pin deformation effect to the flow characteristic in the fuel bundle was obtained by the PIV, LDV measurement in the water flow examination.
