Analysis and comparison of direct inversion and Kalman filter methods for self -powered neutron detector compensation

Abstract

Many light-water reactors use self-powered neutron detectors (SPNDs) to monitor neutron flux. Some SPNDssuffer from delayed response. To compensate for this inherent delay, many methods such as the direct inversionmethod (DIM) and the Kalman filter method can be used. In the current investigation, these two methods wereapplied to the most common SPNDs, rhodium SPND (Rh-SPND) and vanadium SPND (V-SPND). The DIM, aleading compensation method, is used for V-SPND and Rh-SPND response compensation. The Kalman filter,which is a closed-loop compensation method, has also been developed for both SPNDs. The performance ofthe DIM and Kalman method for V-SPND and Rh-SPND was computed and surveyed with various samplingtimes. To evaluate the sensitivity of the compensator algorithm to miscalculations of the prompt fraction ofthe detector signal, computations were also conducted with various prompt fractions. Results show that theKalman method is much more stable with different prompt fractions. Both methods improve the responsetime of V-SPNDs and Rh-SPNDs, and thus would allow them to be used for reactor protection, reactor controlfunctions, reactor core monitoring, and for fulfilling surveillance requirements.