Response to small reactivity perturbations in an oxide and metal fuelled medium-sized liquid-metal fast breeder reactor

The response to small reactivity perturbations of a medium-sized (500 MWe power) liquid-metal fast breeder reactor with oxide and metal fuel, has been studied using frequency and time domain analyses. The study indicates that the metal fuelled core is more sensitive to small reactivity perturbations than the oxide fuelled core. However, both cores satisfy the linear stability criteria for such reactivity perturbations. The methodology used and details of the results are presented. The frequency range of the effectiveness of certain reactivity feedbacks responsible for passive safety in the reactor is also indicated. (Author)