"Methods for the control of fission-product lanthanides in FCCI between U-10Zr and HT-9" 

Emily Higley, MSE PhD Candidate 

Advisor: Professor Maria Okuniewski

WebEx Link

ABSTRACT

U-10Zr is a candidate metallic fuel for Gen IV nuclear reactors. It is proposed for use with HT9 stainless steel cladding. However, due to fuel swelling, fuel-cladding contact occurs, leading to chemical interaction known as FCCI. Due to this phenomenon, the fuel constituents and lanthanide fission products diffuse into the cladding material, leading to the formation of low melting point eutectics and a decrease in the effective thickness of the cladding material, which can lead to rupture. Methods that have been proposed to mitigate FCCI interaction include the addition of dopant elements to the fuel and the insertion of a barrier layer between the cladding and fuel. However, radiation testing is lacking in both areas, and many out-of-pile diffusion tests involving lanthanides are non-representative as they do not account for synergy between lanthanides. This work discusses the parameters considered in both FCCI mitigation approaches and the current state of research into said approaches.