[en] Due to the limited fossil fuel energy resources and the almost fully utilized hydro energy, Egypt has been considering for sometime the various options for satisfying the increasing demand for electricity, including nuclear energy. This thesis emphasizes decisions concerning the impact of nuclear power plant on Egyptian Electrical Grid.This work presents the dynamic modeling and simulation of load flow and transient stability analysis to evaluate the Egyptian Electrical grid. The complex power system is modeled and simulated using Power System Simulator for Engineer (PSS/E). The building blocks of the dynamic model of a power system are presented. A detail of modeling for Egyptian Electrical power network is discussed. It presents an introduction of the load forecasting, and proposal on Egyptian Electrical grid in year 2018. This work presents definitions of nuclear power plant (NPP) and the most widespread power plant reactor types. A detailed representation, analysis, mathematical model, simulation of nuclear power plant and simulation results is also given.This thesis explains the characteristics of the electric grid, its relationship with the NPP, the interaction of electrical grid and nuclear power plant, and the reasons why a reliable grid is so important to the NPP.This thesis proposes a new design of power plant reactor controller for the nuclear power plant. A detailed representation, analysis, mathematical model, simulation of nuclear power plant control and simulation for different disturbance of nuclear power plant on the Egyptian Electrical Grid results is also presented.