Fuzzy Sliding Mode Control for Spatial Control of Large Nuclear Reactor

Spatial oscillations developed in a large nuclear reactor like an advanced heavy water reactor (AHWR) needs to be controlled properly for their safe operation. These spatial oscillations in the neutron flux distribution are developed due to xenon reactivity feedback. If these oscillations are not controlled properly, then a serious situation may occur in the reactor core causing "flux tilting." Further, situations such as on-line refueling might cause transient variations in flux-shape from the nominal flux-shape. For analysis and control of spatial oscillations in AHWR, it is necessary to design a suitable control strategy, which will be able to stabilize these oscillations. In this paper, a fuzzy sliding mode controller (FSMC) is proposed for spatial control of AHWR. The FSMC approximates the discontinuous control of sliding mode control (SMC) to minimize the chattering and to improve the overall performance of the system. Through the dynamic simulations, it is observed that the designed FSMC is able to suppress spatial oscillations developed in AHWR and performance is found to be better as compared to recently proposed approaches in the literature.