Improved Techniques of Analog and Digital Dynamic Compensation for Delayed Self-Powered Neutron Detectors

Practical application of dynamic perturbation measurements for on-power determination of important parameters of nuclear reactors by means of delayed reacting neutron detectors is only possible, if a correction method is given to measure the time-dependent neutron flux behaviour without delay and with high accuracy. An improved model of dynamic signal compensation is presented and illustrated by examples of analog and digital correction methods.
Knowing the transfer function of the neutron detector, it is possible to invert a dynamic (prompt jump response) system by transforming the output equation of the state equation system to the input. An analog circuit corresponding this inverse detector kinetics was developed. On the other hand a recursive digital algorithm of high computational speed and accuracy with regard to real-time processing was found.
The improved analog and digital dynamic compensation methods were developed and used in German and Hungarian nuclear power plants with pressurized water reactors of VVER type. By means of the named correction methods the time- and space-dependent neutron flux behaviour during power changes or reactivity perturbations was followed to estimate reactivity coefficients like differential control rod worths or power coefficient.