• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.11 no.3
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• pp.13-19
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• 2015

This study was aimed at the heating tank with a screw-rotation device for improving the thermal efficiency of electric boiler. In the proposed system, analysis items were the heater rod surface temperature variation, reaching time for set temperature and thermal efficiency. The following conclusions are obtained from this experimental study. (1) When screw speed increases, the time reaching for set temperature tended to be shorter. (2) When the rotation speed becomes 300 rpm, the surface temperature difference between the right and left heater rod decreases by 49%, from $19.7^{\circ}C$ to $9.7^{\circ}C$ in average. (3) When the rotation speed is over 250 rpm, proposed heating tank structure appeared to be effective in terms of thermal efficiency. Thermal efficiency with the rotation speed 300 rpm is improved by 3.8% compared to the case of rotation speed 0 rpm.

• Nuclear Engineering and Technology
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• v.22 no.1
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• pp.75-81
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• 1990

Experiments to predict the thermal contact conductance between the fuel pellet and cladding have been performed, which is important to determine the temperature distibution within the fuel rod. UO$_2$and Zircaloy-2 are used in these experiments. The measuring apparatus is composed of a presser which controls the contact pressure, a thermometer with 5.5 sheathed thermocouples, a vacuum pump, pellet and cladding rods, and two heating devices, etc. The thermal contact conductances were measured with varying the contact pressure and surface roughnesses of UO$_2$and Zircaloy-2 bars. The results show that an increase in the contact pressure and a decrease of surface roughness resulted in increase of the thermal contact conductance. Finally, a fitting correlation has been established and compared with widely-used correlations.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.3
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• pp.165-172
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• 2016

An experimental study of the thermal-hydraulic characteristics of passive safety systems (PSSs) was conducted using a system-integrated modular advanced reactor-integral test loop (SMART-ITL). The present passive safety injection system for the SMART-ITL consists of one train with the core makeup tank (CMT), the safety injection tank, and the automatic depressurization system. The objective of this study is to investigate the injection effect of the PSS on the small-break loss-of-coolant accident (SBLOCA) scenario for a 0.4 inch line break in the safety-injection system (SIS). The steady-state condition was maintained for 746 seconds before the break. When the major parameters of the target value and test results were compared, most of the thermal-hydraulic parameters agreed closely with each other. The water level of the reactor pressure vessel (RPV) was maintained higher than that of the fuel assembly plate during the transient, for the present CMT and safety injection tank (SIT) flow rate conditions. It can be seen that the capability of an emergency core cooling system is sufficient during the transient with SMART passive SISs.