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 SPNDs suffer from delayed response. To compensate for this inherent delay, many methods such as the direct inversion method (DIM) and the Kalman filter method can be used. In the current investigation, these two methods were applied to the most common SPNDs, rhodium SPND (Rh-SPND) and vanadium SPND (V-SPND). The DIM, a leading 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 of the DIM and Kalman method for V-SPND and Rh-SPND was computed and surveyed with various sampling times. To evaluate the sensitivity of the compensator algorithm to miscalculations of the prompt fraction of the detector signal, computations were also conducted with various prompt fractions. Results show that the Kalman method is much more stable with different prompt fractions. Both methods improve the response time of V-SPNDs and Rh-SPNDs, and thus would allow them to be used for reactor protection, reactor control functions, reactor core monitoring, and for fulfilling surveillance requirements.