Fast Reactor Fuel Performance Model Development

The status of fast reactor mixed-oxide fuel performance model development, involving the OLYMPUS and CYGRO-F codes, is reviewed. Input information in several critical areas is examined including: the swelling, irradiation creep, and ductility of stainless-steel cladding; and the swelling and plasticity of mixed-oxide fuel. The predictions from the two codes are illustrated by parametric studies and application to high fluence/burnup ratio fuel rods of interest to the LMFBR program. The analytical studies indicate the major effects of stainless-steel swelling on fuel rod performance and the relationship between fuel density and cladding creep strain.