Abstract
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.
Highlights
Generally, nuclear power plants (NPPs) operate as the primary base energy source in electricity grids, which means in most cases, the core power or electrical power of NPPs need to keep constant [1]
The simulation with RELAP5 verifies the performance of the power and temperature control system based on the frequency domain method
It can be found that under the power controller Dreac− power, the core power can track the setting power accurately; under the temperature controller Dfeedwater−coretemp, the average core temperature keeps constant with the action of Dfeedwater−coretemp, which means in the primary loop, the coolant is safety and has large margin the core power changes significantly
Summary
Nuclear power plants (NPPs) operate as the primary base energy source in electricity grids, which means in most cases, the core power or electrical power of NPPs need to keep constant [1]. A n nodes heat transfer model with some simplifying hypotheses, include single fuel, gap, clad, coolant, has been implemented with neglect of axial heat conduction. The thermal power density q fuelj , which is calculated by neutron kinetics equation, can be regarded as input of core heat transfer system. This linear time-invariant thermal hydraulic dynamic model can be passed from time domain to frequency domain by Laplace transform method (considered the initial condition is zero): out (s) q l (s). (4) Complete Coupled Model The complete coupled model provides as input variables the reactivity and mass flow rate of the heat exchanger, which can be shown as figure 7: Fig. Complete coupled model based on SIMULINK
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