Numerical Investigations of the Fluid Flow and Heat Transfer and Construction of Control System for the Canadian Supercritical Water-Cooled Reactor Power Plant
Abstract
Canada participated in the Generation IV nuclear reactors with the Supercritical Water-Cooled Reactor (SCWR) concept. This work focuses on the numerical studies of the fluid flow and heat transfer of the supercritical water in the nuclear reactor fuel bundle, and the construction of the linear dynamic model and the design of the control system for the Canadian SCWR power plant.
Firstly, the fluid flow and heat transfer of the supercritical water in the vertical tube and the rod bundle is numerically investigated to evaluate whether the existing turbulent models could successfully caption the wall temperature variations at supercritical conditions by comparing the numerical results with the experimental data. The turbulent models that have better performance are modified using a variable turbulent Prandtl number model. The application of the proposed turbulence model shows a great improvement in the prediction of the wall temperatures under supercritical conditions. Accordingly, the full-scale simulation of the fluid flow and heat transfer of the supercritical water flow in the reactor fuel rod bundle was performed by the proposed turbulent model. The results show that the circumferential cladding surface temperature distribution is extremely non-uniform and the maximum cladding surface temperature for each fuel rod also shows large differences. In addition, the effects of operating conditions on the heat transfer of upward supercritical water flow in the reactor fuel bundle are studied numerically. The wall temperatures generally increase with the increase in the inlet temperature, heat flux, or the decrease in the mass flux. Buoyancy-affected zones mainly exist at the region around the pseudocritical temperature.
In this work, the design of the feedback control system for the SCWR is also carried out. The dynamic relationships between inputs and outputs of the reactor are obtained through transient computational fluid dynamics (CFD) simulations. The designed feedback control system can regulate the reactor back to the design point timely. Finally, a linear dynamic model for the entire SCWR power plant is developed, which includes the reactor, feedwater pump, outlet plenum, main steam line, turbine, and condenser. The dynamic characteristics of the system and the steady-state interaction between different inputs and outputs of the system are analyzed. The control system for the SCWR power plant is constructed and the performance of the control system is satisfactory.