Speaker
Description
The behavior of fuel and thermal-hydraulics is strongly interdependent during transient conditions. In particular, during a Loss of Coolant Accident (LOCA), the cladding temperature and internal rod pressure increase significantly due to the loss of effective heat removal by the coolant. This can lead to severe cladding deformation. If the cladding undergoes large deformation or rupture, it may obstruct the coolant flow, thereby degrading the reactor’s coolability and potentially leading to a severe accident. Accordingly, it is critical to evaluate and quantify the consequences of design basis accidents such as LOCA with respect to established safety criteria. To address the complex interactions between fuel and thermal-hydraulic behavior in such scenarios, various multiphysics coupling studies have been conducted in Korea. Notably, integrated analysis systems such as MARS-KS/FRAPTRAN, CUPID/FRAPTRAN, CUPID/MERCURY, and MARS-KS/CUPID have been developed to simulate these coupled phenomena. This study provides an overview of the current status of multiphysics-coupled analysis research in Korea. Coupled analysis approaches have proven to be valuable tools for improving the understanding of fuel behavior under accident conditions. Since fuel behavior is highly sensitive to the prevailing thermal-hydraulic environment—and conversely, thermal-hydraulic behavior is influenced by fuel deformation (e.g., through changes in flow channel geometry and local heat generation)—a coupled analysis framework enables more accurate prediction by providing realistic boundary conditions for both domains.
