Design study of metal fuel sodium-cooled fast reactor, 3; Core and transient characteristics of the lower gas plenum metal fuel cores

Okano, Yasushi; Naganuma, Masayuki  ; Okubo, Tsutomu; Ogata, Takanari*

A metal fuel core has specific features, in comparison with a mixed oxide fuel core, on higher heavy metal density, harder neutron spectrum, and more efficient neutron utilization, although temperatures of coolant, cladding and fuel rapidly increase nearly their constraints under Unprotected Loss-Of-Flow event (ULOF). In this research, characteristics and performances of metal fuel cores, using a novel concept on metal fuel configuration: using lower gas plenum in fuel pins, are evaluated through reactor core design studies and transient analyses on ULOF conditions.