Inherent and passive safety sodium-cooled fast reactor core design with minor actinide and fission product incineration

A self-consistent nuclear energy system (SCNES) can be a promising option a s a future nuclear energy source. An SCNES should fulfill (a) efficient ene rgy generation, (b) fuel production or breeding, (c) burning minor actinide s with incinerating fission products, and (d) system safety. We focus on th e system safety and present a simple evaluation model for the inherent and passive power stabilization capability of intact fast reactor cores under t he conditions of an anticipated transient without scram (ATWS), i.e., self- controllability. The simple evaluation model is referred to as the "reactivity correlation m odel." The model assesses self-controllability of a core based on the capab ilities of reactivity feedbacks to stabilize transient power and maintain t emperatures within predefined safety limits. Here the safety limits are "no fuel failure" and "nonboiling of coolant." The reactivity correlation model was used to survey the self-controllabilit y for metallic-fueled fast reactor cores. The survey was performed by selec ting the core volume fractions of fuel, coolant and structure; the arrangem ent of material compositions; and core configuration. A variety of reactor cores were examined, ranging from a standard 100-cm height to a flat 40-cm height. The effect of additions of sodium plena and channels, increased/dec reased fuel volume fraction (Vf), loading 0 to 10 wt% minor actinides, and installing fission product-burning assemblies was also examined. The core p erformances were evaluated relative to tolerances against typical ATWSs, i. e., unprotected transient overpower and unprotected loss of flow. An optimu m fast reactor core with the self-controllability as well as well-balanced tolerance against ATWSs resulted The performance of this optimal core was e xamined for the other three prerequisites of a self-consistent nuclear ener gy system.