Supercritical Water-cooled Fast Reactor(SCWFR) presents features of combining fast and light water reactor characteristics in one design.The coolant mass flow rate is just as 1/8 as in the BWR

and the neutron energy is harder than in PWR

so it would has the breeding ability.In this paper

using different models of improved Flower-SCWFR core

the void reactivity effect

power distribution

and breeding ratio are analyzed by core zoning scheme

axial coolant densities zoning

seed and blanket assembly with suitable P/D value

MOX fuel with different design and enrichment zoning

and solid uranium matrix cooled by internal clad channels in blanket assembly.Finally

an optimized modal of the improved SCWFR cores-"Flower type" is obtained.