• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.1-8
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• 2018

In this study, a small-scale siphon breaker experimental facility was designed to examine the validity of the Siphon Breaker Simulation Program (SBSP). To design the experimental facility, the simulation results of the C factor, Chisholm B coefficient, and Undershooting Height (UH) were obtained by SBSP. The major parts of the experimental facility were the upper tank, lower tank, downcomer, and Siphon Breaker Line (SBL). The area of the Upper tank was $0.09-m^2$ with a height of 0.65-m. The height of the downcomer was 1.6-m. Pressure transmitters and an electronic scale were used to obtain the experimental results. The experimental variables were the sizes of Loss of Coolant Accident (LOCA) and SBL. The experimental results were analyzed by UH. The SBSP well predicted the UH with an error of 2.5%. Overall, it is possible to design siphon breakers with various scales using SBSP.

• Nuclear Engineering and Technology
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• v.46 no.6
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• pp.817-824
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• 2014

To ensure the safety of research reactors, the water level must be maintained above the required height. When a pipe ruptures, the siphon phenomenon causes continuous loss of coolant until the hydraulic head is removed. To protect the reactor core from this kind of accident, a siphon breaker has been suggested as a passive safety device. This study mainly focused on two variables: the size of the pipe rupture and the timing of air entrainment. In this study, the size of the pipe rupture was increased to the guillotine break case. There was a region in which a larger pipe rupture did not need a larger siphon breaker, and the water flow rate was related to the size of the pipe rupture and affected the residual water quantity. The timing of air entrainment was predicted to influence residual water level. However, the residual water level was not affected by the timing of air entrainment. The experimental cases, which showed the characteristic of partical sweep-out mode in the separation of siphon breaking phenomenon [2], showed almost same trend of physical properties.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.346-353
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• 2016

In the design conditions of some research reactors, the siphon phenomenon can cause continuous efflux of water during pipe rupture. A siphon breaker is a safety device that can prevent water efflux effectively. However, the analysis of the siphon breaking is complicated because many variables must be included in the calculation process. For this reason, a simulation program was developed with a user-friendly GUI to analyze the siphon breaking easily. The program was developed by MFC programming using Visual Studio 2012 in Windows 8. After saving the input parameters from a user, the program proceeds with three steps of calculation using fluid mechanics formulas. Bernoulli's equation is used to calculate the velocity, quantity, water level, undershooting, pressure, loss coefficient, and factors related to the two-phase flow. The Chisholm model is used to predict the results from a real-scale experiment. The simulation results are shown in a graph, through which a user can examine the total breaking situation. It is also possible to save all of the resulting data. The program allows a user to easily confirm the status of the siphon breaking and would be helpful in the design of siphon breakers.