Study on the Application of Temperature Difference in the Evaluation of Pipe Break Size in Recirculation Systems Based on Thermal-hydraulic Model Analysis

Abstract: This study investigates the temperature difference between recirculation loops following an instantaneous pipeline rupture. The analysis shows that the pipe rupture leads to the conversion of energy in an open system, resulting in the coolant escaping from the broken exhibiting a lower temperature compared to the intact loop. A theoretical model based on energy balance principles effectively explains these temperature differences. Validation through the Modular Accident Analysis Program (MAAP5) simulations and training simulator results confirms that both tools accurately predict temperature changes during station blackout and loss of coolant accident scenarios. This study examines the effects of coolant pipe ruptures on the recirculation system and compares the resulting trends with the simulator data. The model can serve as a foundation for future quantitative research, enabling a deeper understanding of the recirculation system during a break transient period. The use of computer simulation codes will ensure the main phenomena, improve accident management strategies, and establish a basis for future quantitative analyses. And, the results of this study also indicate that the correlation between the temperature difference between pipelines and the break size of pipelines is more strongly assisted by the peak cladding temperature.