b'Figure 1. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) of a cross section of as-cast AFA with UN+U (2.5 wt%) annealed at 750C-1000 hr. UN pellets were delaminated from the diffusion couple post annealing. Aluminum Nitride (AIN) formed along the interface of as-cast AFA and UN pelletibility will be useful for evaluatingAFAs and as-cast AFAs for 500 and defining key parameters ofand 1000 hrs. Static liquid metal operation temperature, fuel impuri- immersion experiments have been ties and coolant chemistry relevantcompleted between UN, UN+U(2 to the deployment of this fuel- wt%), UN + U 2 N 3(3 wt%), and UN coolant-cladding system for LFRs. + UO 2 (3 wt%) with liquid lead at 550C and 750C at 500 and 1000 Accomplishments:hrs. UN powders were provided by The technical goals of the researchLANL, and the AFA coupons were are to characterize the chemicalprovided by ORNL. Fabrication interaction and compatibilityof uranium nitride pellets and among the fuel-cladding-coolantexperimentation and character-system for the operation of LFRsization was performed at RPI. at 550 and 750C. Fuel-cladding diffusion couple experiments wereAcross all diffusion couple tests, conducted between UN, interdiffusion of major constituent UN + U (2.5 wt%), and UN + UO 2 elements can be observed between (3 wt%) with both preoxidizedUN and as-cast AFAs when tested 2023|AFC ACCOMPLISHMENTS 149'