Fuzzy-like PD controller for spatial control of advanced heavy water reactor

Abstract

Spatial oscillations in the neutron flux distribution due to xenon reactivity feedback requires stringent control in large nuclear reactors, like advanced heavy water reactor (AHWR). If the spatial oscillations in the power distribution are not controlled, power density and rate of change of power at some locations in the reactor core may exceed limits of fuel failure due to ‘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 stabilize these oscillations. In this paper, a simplified scheme to design a conventional fuzzy logic controller for spatial control of AHWR is presented. This scheme known as fuzzy-like proportional derivative (FZ-PD) controller, uses robust PD (proportional derivative) type rule base. Due to robust rule base structure, tuning of scaling factors is greatly reduced. The non-linear coupled core neutronics-thermal hydraulics model of AHWR considered here represented by 90 first order differential equations. Through the dynamic simulations, it is observed that the designed FZ-PD controller is able to suppress spatial oscillations developed in AHWR and its performance is found to be robust.