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Fujii, Tadashi; ; ; Sakai, Takaaki; ; Oki, Yoshihisa;
JNC TN9400 2002-049, 78 Pages, 2002/09
JNC-TN9400-2002-049.pdf:3.72MB
The conceptual design study of the large-scale sodium-cooled reactor is in progress in the "Feasibility Study on Commercialized Fast Reactor Cycle Systems (F/S)". The direct water pool storage system is being examined as a candidate concept to simplify the fuel handling facility for the sodium-cooled reactor. In this concept, the decay heat of a fuel subassembly is relatively higher (18kW which is about 4.5 times of the Ex-vessel Storage Tank system in the demonstration FBR). Therefore, the information about the cooling characteristics of the fuel subassembly are lacking in cases of submergence process at a normal operation and cooling water injection process from upper part of the subassembly at a transfer accident. Accordingly, the understanding of the cooling characteristics of the fuel subassembly in higher decay heat condition was pointed out as one of the thermal hydraulic problems which influence the realization of the plant concept. Using the single heater pin equipment, fundamental tests were conducted with the parameters of the thermal conditions of a fuel pin, the outlet shapes of it, the submergence speeds and so on. Then, following basic data were acquired to be reflected in the actual plant design. (1)Cooling modes of the normally submergence tests and water injection tests were identified by visualization of the boiling behavior in the test section and the temperature change of the heater pin. (2)The initial temperature of the heater surface and the blockage size of the outlet of test section were dominating factors to the cooling completion time. (3)Maximum temperature rise of the heater surface was about 4K in normally submergence tests and 6K in water injection tests, respectively. Therefore, the heater was well cooled without significant temperature rise.(4)In the normally submergence tests, the pressure of the upper part of the test section did not exceed the lower part pressure and a water level rise in the test section was not obstructed ...
Iitsuka, Toru; Oki, Yoshihisa; Kawashima, Shigeyo*; Nishimura, Motohiko; Isozaki, Tadashi; Kamide, Hideki
PNC TN9410 98-022, 58 Pages, 1998/03
Assessment of the maximum temperature and the position of the hot spot is the most important issues on the reactor safety when the local subchannel porous blockage is occurred. From these background, authors are going to perform a sodium experiment with 37-pin bundle test rig simulating the porous blockage, to understand the phenomena and acquire data for thermal-hydraulic analysis code validation. Before the execution of sodium test, one basic experiment and some using subchannel analysis code ASFRE-III had been done. The basic experiment was a water test to examine the pressure loss characteristics of the porous blockage. The pressure loss correlation derived from the water test was applied to the subsequent subchannel analysis of the 37-pin bundle sodium test rig. The analysis such predicted that the difference between the maximum temperature and the inlet temperature would be in propotion to the power to flow rate ratio, within the condition of the power=100
400 W/cm and the flow rate =200480 
/min. And it was also shown that the maximum subchannel temperature would not over the operational limit temperature 650 
C, if the power to flow rate ratio were kept lower than 0.75(W/cm)//min). The map was made to predict the maximum temperature from the experimental conditions.
Hirabayashi, Masaru; Kobayashi, Jun; Tokuhiro, Akira; Oki, Yoshihisa; ;
PNC TN9430 98-002, 29 Pages, 1998/01
no abstracts in English
Tokuhiro, Akira; Hishida, Koichi; Oki, Yoshihisa
PNC TN9410 96-275, 59 Pages, 1996/10
Particle Image Velocimetry (PIV) describes a velocity measurement technique for gas and liquid flows whereby, as the name implies, movement of tracer particles in motion with the flow are recorded as images. The particles are framr-to-frame "tracked by one of several correlation techniques from which a 2D vector field can be generated. A 3D vector field is also possible. The measurement method takes advantage of current computer, CCD camera and laser light technologies for its image processing needs. A laser light sheet is typically used to illuminate the tracer particles in the flow field of interest and when implemented accentuates the constrast between the particle and the transparent medium. One can also apply Laser Induced Fluorescence (LIF) in order to further distinguish the tracer particles, the transparent, continuous medium and any light reflecting surfaces in the flow field such as the interface of a gas bubble rising in a liquid. It is also possible to deduce the temperature field from LIF images. In the present work an introduction to PIV is given by way of an example. The selected flow configuration is that of wake-flow behind a bubble and its solid equivalent. By solid equivalent we mean a solid model with approximately the equivalent bubble breadth and volume. This two-component, two-phase flow aptly demonstrates the applicability of PIV to spatio-temporal flows. Use was additionally made of an Infrared Shadow Technique (IST) in order to capture the unlit image (shadow) of the bubble or solid within the flow field. By triggering both the laser and infrared light sources with the CCD camera, the shape of the object as well as the flow field was simultaneously recorded. Besides the 2D vector field, calculations of the vorticity, Reynolds stress and turbulent kinetic energy (
) distributions were made. The results indicate that for counter-current flow (U
sim$0.245 m/s) of water in a square channel (100 mm) with a single air bubble of ...
*; *; *; Oki, Yoshihisa*
PNC TJ9214 88-007, 119 Pages, 1988/12
Pressure drop characteristics and possible cavitation occurrence have been investigated on the Joyo receptacles and nosepieces as part of the Joyo Advanced Core Study. The occurrence of cavitation is of particular important on the part of non-replaceable components. Thus, visual observation was made with particular emphasis on cavitation on the receptacle side. Fixed-type of cavitation has been observed on the receptacle wall of Zone-5. In order to suppress this type of cavitation, flow testing has been made using a nosepiece with a large orifice diameter on the second stage. For this case, no cavitation has been observed on the receptacle wall, thereby demonstrating one possible cure for cavitation on the Zone-5 receptacle.