| Abstrak/Abstract |
The failure of the active cooling system in the accident case of the Fukushima Daiichi
nuclear power plant has become a problem in developing a passive cooling system by utilizing
the applicable natural laws. The natural circulation flow as the basis of the passive cooling
principle is very dependent on the temperature or power parameters, as well as geometric
parameters such as the total length of the pipe, diameter, and height difference between the
cooling and heating sections. So that the phenomenon of changes in natural circulation flow rates in passive cooling systems based on geometric parameters in nuclear reactor safety systems is an essential concern in similar research worldwide. This study aims to analyze changes in natural flow rate with water working fluid in laminar conditions based on geometric parameters with variations in temperature differences on the hot and cold sides using the FASSIP-04 Rectangular Loop design. Research has been carried out using data analysis methods based on changes in geometric parameters (boundary conditions, BC) and operational parameters (initial conditions, IC). The analysis is based on 180 the amount of data generated based on calculations. The study shows that only the rectangular loop with a total length of eight meters has the optimum flow rate. The flow rate in the rectangular loop with a pipe diameter of 1 inch with a temperature difference between the cold side and the hot side of 70oC has a natural circulation flow rate of 0.76 m/s. A rectangular loop with a pipe diameter of 2 inches and a temperature difference between the cooler and heater areas of 80oC has a natural circulation flow rate of 0.87 m/s. On a 3-inch diameter loop, the temperature difference between the cold and hot sides is 80oC and has a natural circulation flow rate of 0.89 m/s. The difference in the natural circulation flow rate value based on the diameter of the 1-inch loop against the 2-inch loop is 14%, while the 2-inch loop against the 3-inch loop is 2%. So in this study, increasing the flow rate from a 2-inch diameter loop to a 3-inch loop is not too significant. However, a significant increase occurs in a 1-inch loop to a 2-inch loop
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