IBR-2M Reactor Power Feedback Parameters Evaluation Using Square Reactivity Oscillations

The parameters of a mathematical model of power feedback are evaluated on the basis of an analysis of transient power processes arising in the IBR-2M reactor as a result of intentional square oscillations of the reactivity during operation in a self-regulation regime. The power feedback is described by three linear difference equations and represented in the form of three aperiodic elements connected in parallel. Two components play the role of negative and one component positive feedback. The total feedback is negative, i.e., it has a stabilizing effect on the operation of the reactor. The slowest negative component of power feedback is probably due to axial swelling of the fuel as it heats up. Since the power feedback parameters change in the course of operation, their periodically repeated evaluations are one way of securing the operational safety and reliability of the reactor.