Electronic Thesis and Dissertation Repository


Master of Engineering Science


Mechanical and Materials Engineering


Prof. Zhang, Chao


A method to design the closed-loop control system for the 37-element vertical Canadian supercritical water-cooled reactor (SCWR) fuel bundle has been proposed in this study. The dynamic models used in the controller design are obtained based on the computational fluid dynamics (CFD) simulations of the fluid flow and heat transfer of the supercritical water in the SCWR fuel bundle. The Reynolds Stress Model is used in the CFD simulations. Comparisons of the supercritical water flow behaviors and heat transfer phenomenon in the single- rod channel and multi-rod channel are also carried out. The results show that there are secondary flows in the single rod channel. The maximum cladding surface temperatures in the single rod channel and the multi-rod channel are different. Therefore, the multi-rod channel is used to conduct the numerical simulations of the fluid flow and heat transfer in the Canadian SCWR and the CFD data are used to construct the control system for the SCWR.

To construct the dynamic control model, the transient thermo-hydraulic behaviors of the supercritical water in the SCWR fuel bundles are predicted numerically. Step perturbances are used to generate the dynamic responses between the inputs and outputs. The linear dynamic control models are constructed by the system identification technique based on the CFD simulation data. Then, the linear dynamic models are validated by comparing the results with those from full-scale CFD simulations. Based on the linear dynamic models, the control system with two PID controllers is designed to make the SCWR return to the design condition when perturbances occur. The performance evaluation of the proposed control system is carried out by using it in a closed-loop control system for the Canadian SCWR.