2017 | AFC ACCOMPLISHMENTS 60 Response of U3Si2 to steam and pressurized water at LWR operating temperatures Principal Investigators: Andy Nelson Collaborators: E.S.Wood, J.T.White Figure 1. Compares the microstructures of U3Si2 oxidized under H2O and air. New Accident Tolerant Fuel (ATF) concepts such as U3Si2 offer potential benefits to reactor operation and performance, but also introduce uncertainties. The behavior of U3Si2 when exposed to pressurized water and steam at temperatures between 250 and 400C has established the susceptibility of U3Si2 to hydriding.This behavior has not been previously observed in U-Si compounds, and must be better understood to project its response under a leaker or Loss of Coolant Accident (LOCA) scenario. Execution of tests to assess vulner- abilities of proposed ATF concepts is a key component of their qualifica- tion for commercial Light Water Reactor (LWR) deployment. Many proposed cladding or fuel systems possess properties or specific performance attributes that would be superior to the reference UO2