Verification of the VVER-1200 Reactor Dynamic Model Consisting of a Single Fuel Node Adjacent to Two Coolant Nodes

Since the modern automatic control theory imposes constraints on the mathematical models of control objects, further development and verification of mathematical models of nuclear power facilities suitable for the synthesis of automatic power control systems is a topical problem. This article deals with a low-order dynamic model with lumped parameters of the Russian-designed pressurized water reactor, as well as with its verification with experimental data from the full-size simulator of the VVER–1200 nuclear reactor in two tests involving the variation of the position of group 12 of CPS CR and the variation of the inlet coolant temperature. This model was created as a MATLAB S-function lv.2 model because of its capability to process any input signals. Within this approach, the equation describing the heating of the coolant is represented as a «two well-stirred tanks in series» model. The article demonstrates the advantage of the given approach over the conventional approach, where the average temperature of the coolant is determined as the arithmetic mean of the inlet and outlet coolant temperatures on the basis of a test with a sudden change in the reactor inlet coolant temperature. In the frequency domain, the authors carry out the stability analysis of the given model in the state-space form with respect to various external perturbations. Conclusions are drawn about the possibility of using the model as a fifth-order control object for the parametric synthesis of a controller for the automatic power control system of a nuclear power facility.