An axially heterogeneous sodium-cooled fast reactor designed to transmute minor actinides

An axially heterogeneous sodium-cooled fast reactor design is developed for converting minor actinide waste isotopes into plutonium fuel. The reactor design incorporates zirconium hydride moderating rods in an axial blanket above the active core. The blanket design traps the active core's axial leakage for the purpose of transmuting ²⁴¹Aminto ²³⁸Pu. This ²³⁸Pu is then co-recycled with the spent driver fuel to make new driver fuel. Because ²³⁸Pu is significantly more fissionable than ²⁴¹Am in a fast neutron spectrum, the fissile worth of the initial minor actinide material is upgraded by its preconditioning via transmutation in the axial targets. Because the ²⁴¹ Am neutron capture worth is significantly greater in a moderated epithermal spectrum than the fast spectrum, the axial targets serve as a neutron trap that recovers some of the axial leakage lost by the active core.