• International Journal of Advanced Culture Technology
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• v.9 no.3
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• pp.360-366
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• 2021

In this study, we tried to examine how the kinking of the fire hose affects the time taken for initial water discharge by measuring and analyzing the time taken for initial water discharge with different number of kinks at different locations of the hose. The average time taken for initial water discharge was obtained by measuring the time in the unkinked state of the fire hose. Based on this standard, we conducted the experiment by selecting the kinking locations in the hose near the water outlet and nozzle, and setting the number of kinks to 3, 6, 9, and 12. The results of this study are as follows: First, if the fire hose has 5 kinks or more near the nozzle, no water was released. Second, when comparing the case of no kinks and 4 kinks near the nozzle, there was no significant difference in the time taken for initial water discharge. Third, when the fire hose was kinked 10 times near the outlet, the time required for initial water discharge increased by 1.62 seconds on average compared to the case with no kinking, but there was no problem with water discharge. Lastly, regarding the kinking locations of the fire hose, it was found that the greater the number of kinks near the nozzle than near the outlet, the greater the effect on the discharge. As a result, it is concluded that it would be preferable to install non-kinking devices near the nozzle of the fire hose.

• Nuclear Engineering and Technology
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• v.18 no.3
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• pp.200-208
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• 1986

The loss of coolant accident based on a double-ended cold leg break is analyzed with the discharge coefficient (Ca) of 0.4. This analysis covers the whole transient period from the start of depressurization to the complete refilling of the core by using RELAP4/MOD6-EM and RELAP4/ MOD6-HOT CHANNEL for the system thermal-hydraulics and the fuel performance during the blowdown phase respectively, and RELAP4/MOD6-FLOOD and TOODEE2 during the reflood phase. A simple analytical method has been developed to account for the lower plenum filling by approximating steam-water countercurrent flows and superheated wall effects at the downcomer during the refill period. Based on the informations. at the time of EOB (end-of-bypass), the refill duration time and the initial reflooding temperature were estimated and compared with the results from the RELAP4/MOD6, resulting in a good agreement. In addition, some parametric studies on the EOB were performed. The form loss coefficient between upper head and upper downcomer was found to be sensitive to the occurrence of the spurious EOB. Appropriate form loss coefficients should be taken into account to avoid the flow oscillations at the downcomer. The analyses with the six and three volume core nodalizations, respectively, show much similar trends in the system thermal-hydraulic performance, but the former case is recommended to obtain good results.