Please consider attending the following: MATERIALS ENGINEERING SEMINAR "A Comprehensive Study on Neutron Irradiation Effects on Uranium-Zirconium Nuclear Fuel" By Jonova Thomas Purdue MSE Ph.D. Preliminary Exam Advisor: Professor Maria A. Okuniewski ABSTRACT Metallic U-10wt%Zr nuclear fuels are classified as potential fuels for fast breeder reactors as they possess a high fissile density and have increased compatibility with sodium, a frequently used reactor coolant. Despite their advantages when exposed to neutron irradiation in reactors, the fuels are subject to severe damage cascade and microstructural alterations. These microstructural alterations are also accompanied with large concentrations of point defects or defect clusters and fission products that cause severe fuel swelling. Void and bubble cavity growth can cause further swelling in fuels and facilitate the fuel to meet the cladding within which it has been enclosed. Contact between fuel and claddings at elevated temperatures and burnup cause fuel cladding chemical interactions (FCCI) to occur. FCCI is detrimental in reactor programs as they cause inter-diffusion between fuel and cladding constituents, which lead to eventual failure of the fuel. Previous studies on FCCI indicate that U-10wt%Zr fuels inhibit inter-diffusion to a certain extent by forming a Zr barrier between fuel and cladding. Although this may be true, most studies on FCCI done via isothermal diffusion studies between U-10Zr/HT9 fuel-cladding show varied observations on inter-diffusion layers formed and conflicting arguments on the process of formation of the Zr barrier that inhibits inter-diffusion. This report involves a detailed investigation on the swelling mechanism of irradiated U-10wt%Zr fuels and a discussion on the conflicting arguments of formation of the Zr barrier, and inter-diffusion layers. Finally, similarities between FCCI layers in neutron irradiated U-10wt%Zr/HT9 fuel-cladding is compared to observations made from isothermal diffusion experiments. Date: Monday, December 11, 2017 Time: 11:30 A.M. Place: ARMS 1028