THERMAL HYDRAULIC ANALYSIS FOR ENHANCING PASSIVE HEAT REMOVAL SYSTEMS

Nuclear power plants play a pivotal role in satisfying worldwide energy requirements, aiding industrial operations, fostering economic development, and minimizing carbon emissions. The importance of nuclear safety has been heightened by past events such as Chernobyl and Fukushima, emphasizing the continual need for advancements in safety systems and regulations. This study concentrates on elevating the safety standards of nuclear power plants, with a specific focus on the emergency condenser (EC) within the passive safety system of the KERENA reactor.
The EC, a critical component in this context, plays a pivotal role in removing decay heat from the reactor core during emergencies. However, challenges arise in accurately predicting the thermal performance of the EC's secondary side, prompting questions regarding heat transfer models, numerical approaches, empirical models, and cost-effective methods for analyzing thermal-hydraulic behavior.
This thesis aims to improve the predictive and computational modeling capabilities of the thermal-hydraulic dynamics on the secondary side of ECs. A comprehensive review of contemporary heat transfer models is conducted, evaluating their applicability based on experimental data from the COSMEA and NOKO test facilities. Computational Fluid Dynamics (CFD) methods are explored to analyze temperature stratification, with a focus on addressing computational challenges and determining acceptable simplifications.
Recognizing the prevalent use of 1D codes in nuclear applications, efforts are made to develop a practical heat transfer model for integration into these codes, enhancing the precision of simulations. Additionally, the study explores the integration of Artificial Neural Networks (ANN) to model thermal-hydraulic dynamics, leveraging the universal applicability of artificial intelligence.
The findings of this research aim to provide valuable insights for optimizing the efficiency of emergency condenser systems, mitigating the risk of failures, and bolstering the safety of nuclear power plants. By addressing the identified questions and challenges, this thesis contributes to the broader goal of ensuring the reliability and sustainability of nuclear energy as a secure solution for meeting industrial energy demands in the future.