Determination of reactivity based on the inverse point kinetics equation

The error of a method based on the inverse point kinetics equation is analyzed within the framework of a discrete multigroup diffusion model. The method is designed to calculate the reactivity of a nuclear reactor by using the time dependence of the neutron flux measured by a local sensor. It is shown that the approximate reactivity calculated by the method converges to a certain value independent of the sensor's location as the measurement time is increased indefinitely if the reactor structure and properties remain constant starting from a certain time instant.