b'Microstructure and Micromechanical Characterization of Cr Diffusion Barrier in ATR Irradiated U-10Zr Metallic FuelPrincipal Investigator: Yachun Wang, Luca CapriottiTeam Members/Collaborators: Cameron B. Howard, Fei Xu, Daniele Salvato, Kausttubh K. Bawane, Daniel Murray, David M. Frazer, Scott T. Anderson, Tiankai Yao, Sunghwan Yeo, June-Hyung Kim, Byoung-Oon Lee, Jun Hwan Kim, Randall S. FieldingO ngoing U.S. research andThe Cr diffusion development (R&D) has been devoted to exploringbarrier provided a the possibility of ultra-high burnupgood integrity to (30-40 % FIMA) metallic fuels toprevent FCCI between increase uranium (U) resource utili- the U-10Zr fuel and zation in sodium-cooled fast reactorsHT-9 cladding upon (SFRs). However, the fuel/claddingirradiation in ATR to chemical interaction (FCCI) remains8.7 %HM burnup at an a major challenge limiting theaveraged peak inner deployment of ultra-high burnupcladding temperature metallic fuels. One possible solu- (PICT) of 540-550C.tion to mitigate/prevent FCCI is to introduce a diffusion barrier, like Cr, between the fuel and cladding. To investigate the irradiationHT-9 cladding through a collection performance of the Cr diffusionof characterization techniques, barrier, a U-10Zr (wt%) solid fuelincluding Scanning Electron sodium bonded with HT-9 claddingMicroscopy (SEM), in-situ SEM with an internal Cr diffusion barriermicro-tensile testing, and Transmis-was irradiated in the Advanced Testsion Electron Microscopy (TEM), Reactor (ATR) to 8.7 %HM burnupat the Irradiated Materials Charac-at an averaged peak inner claddingterization Laboratory within the temperature of 540-550C. For theMaterials and Fuels Complex at INL. first time, in-depth post-irradiationThe result of this study provides examination on the Cr diffusionin-depth insight into the microstruc-barrier in this fuel was performed attural and compositional stability Idaho National Laboratory (INL). of the electroplated Cr diffusion Project Description:barrier during in reactor irradiation. This research aimed to 1) gainFurthermore, this investigation insight into the potential micro- sheds light on a promising solu-structural and compositionaltion to mitigate/prevent the FCCI changes in the Cr diffusion barrier,in HT-9 clad U-10Zr fuels, which to 2) characterize potential inter- can greatly benefit the adoption actions, and to 3) evaluate theof metallic fuel for SFRs at high or micromechanical properties of theultra-high burnup.Cr diffusion barrier and nearby 164 2023|AFC ACCOMPLISHMENTS'