Lyapunov Stability of Spatially-Dependent Nonlinear Reactor System including an External Primary Heat Exchanger

In the study of reactor system stability, the past work is mainly concentrated in two areas: the study of reactor core stability using either the point model or distributed model, and the study of plant dynamics using a lumped parameter model with time delay. The former study assumed no interaction between the core dynamics and the rest of the components in the system whereas the latter neglected the distributed effect, thus some salient features in the system may be lost. The work presented in this paper analyzes the stability of a distributed reactor system which consists of the core dynamics with nonlinear temperature feedbacks, the external primary heat exchanger, and the coolant loop interconnecting these two major components. The coupled set of nonlinear partial differential equations is treated directly without recourse to the usual lumped parameter approximation. An extension of Lyapunov´s theory, which has been successfully used in the study of distributed core dynamics, is employed to obtain stability criteria for this coupled system.