Investigation of dynamical reactivity effects of IBR-2 moving reflectors

The reactivity effects of two types of moving reflectors are determined in the pulsed regime of the IBR-2 reactor operating at power. For this, the shape of the power pulse on fast neutrons and the power released between pulses as a function of time were measured with good statistical accuracy. A special feature of the dynamical estimate of the neutron-physical parameters is that it was obtained by analyzing the standard operating regime of the reactor. For this, to estimate the parameters of the mobile reflector the reactor was transferred into a stationary (not pulsed) subcritical operating regime in which some fast processes influencing the shape of the power pulse could not be determined. The dynamical method makes it possible to obtain a detailed description, to a high degree of accuracy, of the change in reactivity as the moving reflector rotates.