Research On Compensation Algorithm For Multimode Delayed Signals Of Self-powered Neutron Detectors

During the operation of a nuclear reactor,the neutron flux in the reactor is an important physical parameter of the reactor.In order to ensure the safe operation of the reactor,the real-time and continuous monitoring of the neutron flux is particularly important.Self-powered Neutron flux Detector（SPND）is a small,fully solidified detector with the advantages of simple structure,low cost,easy installation,long life,radiation resistance and high temperature resistance,etc.It is an ideal reactor neutron flux detector.It is widely used in the monitoring of neutron flux in large reactors.The output current signals of the vanadium self-powered neutron detector（VSPND）and rhodium self-powered neutron detector（RSPND）will have a large delay response due to the current generation mechanism of the detector,which will seriously affect the real-time measurement of the neutron flux in the reactor.This has an adverse effect on the control and safety of the reactor.According to the mathematical model of VSPND and RSPND’s current generation,the inverse function calculation is used with different discrete methods to improve the response characteristics,which is conducive to the actual use of the two detectors.In this paper,based on the calculation of the inverse function of the mathematical model of current generation,8 algorithms using 4discrete methods: forward difference transformation method,backward difference transformation method,step response invariance method and bilinear transformation method,are designed to be applied to two kinds of detectors.In view of the different input neutron flux,the designed digital experiment system effectively shortens the response time of the detector output signal and verifies the correctness of the algorithm,At the same time,in order to simulate the complex and variable neutron flux changes in the reactor as much as possible to verify the correctness of the compensation algorithm.In addition to verifying the compensated response time by means of analog signals generated by step-change neutron fluxes,We also selected the analog signals generated by linearly varying neutron fluxes with different slopes and exponentially varying neutron fluxes with different bases.After repeated experiments and analysis of the experimental results,we found that the four algorithms can achieve real-time tracking compensation in the face of more complex neutron fluxes.It provides the feasibility for the two detectors to be used for real-time measurement of neutron flux in the reactor.