Development of Dynamic Models for PWR Nuclear Power Plant Simulation in the Modelica Environment

This thesis presents the development of a dynamic Pressurized Water Reactor (PWR) model, starting with a simplified basic model and progressively increasing its level of detail in both the neutronic and thermal-hydraulic domains within the open-source OpenModelica environment. The secondary thermal-hydraulic circuit is progressively extended from a single-turbine layout to a two-stage turbine configuration and, finally, to a fully regenerative cycle with high-pressure steam extraction and a direct-contact spray condenser. The increased model complexity requires a dedicated initialization strategy based on previously generated .mat simulation state files. From a neutronic standpoint, the original point-kinetics formulation is extended to a two-region axial core model that couples the neutron population and precursor concentration in the upper and lower regions via a diffusive term. A control rod model based on insertion depth is also developed and shown to reproduce the point-kinetics response exactly. The resulting Modelica configurations: Control Rods, Two-Zone, and Spray-Condenser are compared with the IAEA Advanced PWR Simulator at nominal and partial-load steady-state conditions. A steady-state comparison is adopted because the permanent Xenon-135 dynamics implemented in the reference simulator prevent a direct transient comparison. The models closely reproduce the reference thermal-hydraulic behavior, while the remaining discrepancies are attributed to identified structural differences between the models. The results demonstrate the consistency of the developed neutronic and thermal-hydraulic formulations and provide a basis for future extension of the modeling framework to Small Modular Reactor systems.