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JAEA Reports

The Outline of investigation on integrity of JMTR concrete structures, cooling system and utility facilities

Ebisawa, Hiroyuki; Hanakawa, Hiroki; Asano, Norikazu; Kusunoki, Hidehiko; Yanai, Tomohiro; Sato, Shinichi; Miyauchi, Masaru; Oto, Tsutomu; Kimura, Tadashi; Kawamata, Takanori; et al.

JAEA-Technology 2009-030, 165 Pages, 2009/07


The condition of facilities and machinery used continuously were investigated before the renewal work of JMTR on FY 2007. The subjects of investigation were reactor building, primary cooling system tanks, secondary cooling system piping and tower, emergency generator and so on. As the result, it was confirmed that some facilities and machinery were necessary to repair and others were used continuously for long term by maintaining on the long-term maintenance plan. JMTR is planed to renew by the result of this investigation.

JAEA Reports

The ultrasonic wave thermometer sodium test, 1; A summary of test results of the externally mounted ultrasonic transducer for pipe-flow

Hayashida, Hitoshi; Kokaki, Nobuhisa; Ueda, Masashi; Isozaki, Tadashi; Ara, Kuniaki

JNC TN9400 98-001, 54 Pages, 1998/10


Based on the temperature dependence of the velocity of sound in sodium, an ultrasonic thermometer that measures the temperature of sodium non-intrusively is being developed. The principle of the device is based on the propagation time of an acoustic pulse wave, and the back calculation of the sodium temperature. As the part of the development a test was actually carried out in sodium pipe-flow in order to evaluate various aspects of realizing the ultrasonic wave thermometer. The results and conclusions to date are as follows: (1)Within the present test range, the ultrasonic wave thermometer appears relatively insensitive to flow velocity of sodium, pressure of the cover gas and the impurity concentration in sodium. The calculated error of the measured thermometry was in the experiment about 1 $$^{circ}$$C, a smaller value than the expected 2.5$$^{circ}$$C of the system. (2)The ultrasonic thermometer has only been used wherein the thermal expansion coefficient was known and with 200 $$^{circ}$$C as the reference temperatures. For the entire temperature range tested the difference between this approach and a two-point calibration over a temperature range is only expected to be about 1 $$^{circ}$$C. (3)By using the mean value of multiple ultrasonic wave transmit and receive measurements, a value whereby the ultrasonic propagation time was stabilized is obtained. (4)As acoustic coupling material between the ultrasonic transducer and piping, a copper plate was found to be more suitable than a specialized acoustic bonding material. A weight equivalent, area distributed force of 2.0kg/mm$$^{2}$$ was used to press the test copper plate to the pipe. A slightly smaller force appears more than sufficient as well. (5)We found that mounting the ultrasonic transducer to the exterior surface of the pipe by a clamping method is sufficient such that no welding is needed. (6)The in-sodium test period was about 2 months. No noticeable change in measurement characteristics of the ...

JAEA Reports

Fundamental water experiment on subassembly with porous blockage in 4 sub-channel geometry; Influence of flow on temperature distribution in the porous blockage

Tanaka, Masaaki; Kobayashi, Jun; Isozaki, Tadashi; Nishimura, Motohiko; Kamide, Hideki

PNC TN9410 98-024, 94 Pages, 1998/03


In the liquid metal cooled Fast Breeder Reactor, Local Fault incident is recognized as a key issue of the local subassembly accident. In terms of the reactor safety assessment, it is important to predict the velocity and temperature distributions not only in the fuel subassembly but also in the blockage accurately to evaluate the location of the hottest point and the maximum temperature. In this study, the experiment was performed with the 4 sub-channel geometry water test facility. Dimension is five times larger than that of a real FBR. The porous blockage is located at the center sub-channel in the test section and surrounded with three unplugged sub-channels. The blockages used in this study were (1)the solid metal, (2)the porous medium consisted of metal spheres, (3)the porous blockage with end plates covering the side or top faces of the blockage to prevent the horizontal and axial flows into the blockage. The experimental parameters were the heater output provided by the electrical heater in the simulated fuel pins and the flow rate. Temperature of the fluid was measured inside/outside the blockage and velocity profiles outside the blockage were measured. From the comparison of velocity profiles, the flow field inside the blockage depended remarkably on the blockage conditions. Such variation of flow fields affected the temperature distributions. Efficient heat transportation by horizontal flow existed in the upper part of the porous blockage. While, in the lower part of the blockage, the axial flow from the bottom face of the blockage was pre-dominated for the heat removal. Nusselt number defined by the temperature difference between the heater pin surface and the bulk temperature of the unplugged sub-channel was proportional to the power of 0.5$$sim$$0.6 of Reynolds number. This result shows that the dependency of the Nusselt number to the Reynolds number was decided by the heat transfer from the blockage matrix to the coolant at the side of porous blockage.

JAEA Reports

Study for subassembly porous blockage in fast breeder reactors; Pre-subchannel analysis of 37-pin bundle sodium test

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$$sim$$400 W/cm and the flow rate =200$$sim$$480 $$ell$$/min. And it was also shown that the maximum subchannel temperature would not over the operational limit temperature 650 $$^{circ}$$C, if the power to flow rate ratio were kept lower than 0.75(W/cm)/$$ell$$/min). The map was made to predict the maximum temperature from the experimental conditions.

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