Approaches to slowing down the kinetics of a fast reactor as a means of enhancing its self-protection properties

The concept of slowing down the kinetics of a fast reactor, according to which a rapid reactivity insertion is used to reduce the development rate of transients at initial events, is aimed at achieving a higher level of reactor self-protection. The paper presents a set of studies on the engineering and technical implementation of this concept on the example of a high-power fast lead-cooled reactor. Considering a hypothetical initial event with a rapid insertion of a complete reactivity margin, the stability of the reactor with the slowed down kinetics in relation to such an event was analyzed. An updated physical-mathematical apparatus is proposed for evaluating the slowed-down kinetics and calculating the dynamics of transient processes. The basic principles for the formation of a reflector for such a reactor based on formulated criteria for slowing down the kinetics include the use of ²⁰⁸Pb and weakly neutron-absorbing materials, as well as the optimum location of various structural elements in the reflector. The theoretical possibility of achieving a slowed-down kinetics in layouts that meet the developed principles is demonstrated.