An outline is given of simple evaluation models for a recriticality in an attempt to construct a fast reactor core that has high potential to terminate an accident and prevent its progression, under postulated core-damage conditions, into further disruption of the degraded core and into possible recriticality leading to an energetic power excursion. The basic idea to prevent recriticality events is to remove a certain amount of fuel material out of the core in order to keep the core subcritical. Based on the simplified models, general guidelines are given that minimize the amount of fuel removal necessary to avoid recriticality events. Multigroup two-dimensional diffusion calculations are also performed to ascertain the tendency obtained by the simple model for the reactivity insertion due to a core collapse. In the sense of controlled material relocation, the fraction of core materials is identified that should be preferentially removed out of the core to eliminate the recriticality potential.