Comparative study of unprotected loss of flow accident analysis of 1000Â MWe and 500Â MWe Fast Breeder Reactor Metal (FBR-M) cores and their inherent safety

► ULOF analysis of metal (U-Pu-6% Zr) fuelled 500 MWe and 1000 MWe pool type FBR. ► Uncertainties (typically 20%) on the sensitive feedback parameters. ► Sensitive parameters - core radial feedback and sodium void reactivity effect. ► Transient behavior of both 500 MWe and 1000 MWe core are benign under ULOFA. ► For 1000 MWe inherent safety is assured with limited sodium void reactivity.