The Control Rod Drive System (CRDS) plays a vital role in the operation of nuclear power plants, ensuring the safety and stability of reactors by enabling precise control over reactor startup, shutdown, and power regulation. This study focuses on the reliability and performance optimization of Insulated Gate Bipolar Transistors (IGBTs) in the CRDS of nuclear power plants. CRDS is essential for precise reactor control, where the efficiency and thermal stability of IGBT modules are critical for ensuring system reliability under high-power, high-frequency operating conditions. To address the challenges of loss estimation and thermal management, this work establishes a comprehensive IGBT loss model using Simulink, supported by a Foster thermal network model built in COMSOL for accurate junction temperature estimation. The proposed loss model accounts for conduction and switching losses, validated against datasheet-based calculations, and demonstrates superior accuracy under typical operating conditions. By incorporating dynamic thermal modeling, the study provides insights into the coupling effects between power losses and thermal behavior, enabling precise evaluation of junction temperature variations. Results indicate that the developed approach significantly enhances simulation accuracy, improves energy efficiency, and prolongs the service life of IGBT modules. The integration of loss and thermal models offers a robust framework for optimizing IGBT operating conditions, with practical applications in the design and reliability enhancement of CRDS in nuclear power plants. The findings not only provide a theoretical basis for system optimization but also hold broader implications for improving the safety and economy of high-reliability power electronic systems.