Spatial stabilization of Advanced Heavy Water Reactor

Spatial oscillation in neutron flux distribution resulting from reactivity feedbacks due to fission products such as xenon is a matter of concern in large nuclear reactors. Left uncontrolled, the spatial oscillations may lead to “flux tilting” which may put the fuel integrity at peril. Hence during the design stages of any large nuclear reactor, it is essential to identify the existence of spatial instabilities and to design a suitable control strategy for regulating the spatial power distribution. In this paper, the existence of spatial instabilities in Advanced Heavy Water Reactor is investigated, which establishes that this reactor exhibits three modes of spatial instabilities. The paper further explores its stabilization using a control strategy based on feedback of total as well as spatial power distribution signals. The efficacy and robustness of the controller is demonstrated through dynamic simulations.

► This study establishes that the AHWR exhibits three modes of spatial instabilities.
► These modes are identified as first and second azimuthal and first radial.
► Stabilization of these modes using only output feedback is successfully achieved.
► Resultant closed loop system is found to be robust to process side disturbances.