Study on enhanced performance sodium-cooled metal fuel core concepts by adopting advanced fuel and flexible design criteria

Kobayashi, Noboru; Ogawa, Takashi; Oki, Shigeo ; Mizuno, Tomoyasu; Ogata, Takanari*

The metal fuel core is superior to the mixed oxide fuel core because of its higher breeding ratio and compact core size resulting from neutron economics, hard neutron spectrum, and high content of heavy metal nuclides. Utilizing the advantage of the metal fuel core, conceptual sodium-cooled fast breeder reactor designs have been pursued for the attractive core properties of high breeding ratio, small inventory, compact size, low sodium void reactivity, and high transmutation ratio of the minor actinides. Among attractive cores, a conceptual design for a high breeding ratio was performed without blanket fuels. The design conditions were set so a sodium void reactivity of less than 8, a core height of less than 150 cm, a maximum cladding temperature of 650 C, and a fuel pin bundle pressure drop of 0.4 MPa. The breeding ratio of the resultant core was 1.34 without blanket fuels.