The paper presents the simple and efficient analysis method of frequency-domain to control the core power and coolant temperature of Nuclear Power Plants (NPPs). In order to properly describe the neutron kinetic and thermal transmission of NPPs, a one-dimensional dynamic model has been accomplished by using the linearizing in time domain and discretizing in spatial domain, and then the transfer function matrix can be obtained through Laplace transform. Based on the transfer function matrix of NPPs, the effective of different system inputs: reactivity and feed water mass flow, can be analyzed by Nyquist method. On this basis, the power and temperature control system are presented, and the stability is proved in frequency domain. The proposed method is verified by RELAP5 that confirm its performance.
