Design of discrete-time Kalman filter based delay compensator for Rhodium-103 SPND

Rhodium-103 Self-Powered Neutron Detectors (SPNDs) are used in typical Pressurized Water Reactors (PWRs) for flux measurement. They are slow responding neutron detectors. The slow response of Rhodium-103 SPND restricts its direct use for monitoring, control and determination of parameters like neutron flux distribution, local flux peaking. These reactor parameters are indirectly calculated in terms of Departure from Nucleate Boiling Ratio (DNBR) & Linear Heat Generation Rate (LHGR), so that the extracted power limits from Fuel Assembly do not exceed the design limit. Whereas benefits offered by Rhodium-103 SPNDs like simple response, ease in handling and replacement from core etc., make them suitable candidates for this applications. In this paper, the goal is to develop a Discrete-Time Kalman Filter (DTKF) based delay compensator to improve the response time of Rhodium-103 SPNDs. The simulation results of delay compensation algorithm of Rhodium-103 SPND are compared with the collected data from 1000 MWe VVER units-1&2, Kudankulam, India. It is established that the simulation output is in very good agreement with the prompt responding Ex-core (Ion chamber) detectors. This puts the possibility of using Rhodium-103 detectors for fuel health monitoring inside reactor core.