The signal compensation method for the neutron flux in the measurement system using self-powered neutron detector

Self-powered neutron detectors (SPNDs) have been utilized within in-core instrumentation to measure neutron flux for control and core flux mapping in nuclear reactors. To estimate neutron flux with SPNDs, a mathematical dynamic model correlating neutron flux and SPND material has been established. Estimation and signal compensation for neutron flux have primarily been developed using transfer-function-based methods or state-space-based methods. Particularly for the rhodium SPND, to compensate for its delayed response to incident neutron flux input, both groups of compensation methods have been widely applied. This Review details the signal compensation methods of neutron flux using transfer-function-based methods, such as those employing analog circuits, dynamic modeling of neutron flux, compensation of neutron flux, and direct inversion. In addition, signal compensation and estimation of neutron flux using state-space-based methods, such as the Kalman filter and H-infinity filter, are reviewed, along with basic calculations based on certain assumptions. Since there are differences in the characteristics of the two groups of methods for the same type of SPND, review comments are also included regarding the stability of compensation methods, based on results obtained from calculations using certain assumptions.