Kalman Filter-Based Dynamic Compensator for Vanadium Self Powered Neutron Detectors

Large nuclear reactors employ a wide variety of in-core detectors to determine the neutron flux distribution within the core. Among them Vanadium SPNDs are extensively used for flux mapping applications due to their accuracy. However, the slow response characteristics of Vanadium detectors precludes their direct use for reactor protection and regulation applications. Neverthless, by overcoming their inherent time delay, it is possible to use them in such applications. Moreover, benefits offered by Vanadium SPNDs like better life span, simple response characteristics, easiness in handling the replaced SPNDs etc., make them desirable candidates for such applications. Therefore, a method to improve the response time of Vanadium SPNDs would enable them to be utilized for reactor control applications as well as to fulfill core monitoring and surveillance requirements. In this paper, a Kalman filter-based compensator is proposed for online dynamic compensation of Vanadium SPND. Moreover, compensated flux obtained by Kalman filter is compared with the compensated flux obtained from existing dynamic compensators i.e. Direct Inversion and Tustin, and robustness of proposed algorithm is studied. The compensator is validated using the plant data collected from the 540 MWe PHWR units in India. It is established that the compensated Vanadium SPND signals are in very good agreement with the prompt Cobalt SPND signals. This puts the possibility of using Vanadium SPNDs in lieu of Cobalt SPNDs for reactor protection and regulation applications.