b'Impacts on LWR Reactor Performanceand Safety Characteristics of Coated UN FuelPrincipal Investigator: Michael TodosowTeam Members/ Collaborators: Arantzazu CuadraFigure 1. k-infinity vs. burnup.In order to utilize UN fuel in commercial LWRs they must be protected to mitigate potential fuel/coolant interactions.This study performed an initial assessment of the impacts on reactor performance and safety characteristics of 20F Project Description:ollowing the catastrophic accident m of several potentialat the Fukushima Daiichi reactorsScoping calculations were performed coatings on the UN fuelin 2011, major efforts haveto estimate the impact on reactor pellets. Knowledge ofbeen undertaken to develop fuels andperformance and safety characteristics these impacts helps tocladdings with enhanced accidentof coating UN fuel pellets to mitigate inform the selection oftolerance (aka, Accident Tolerant Fuels the fuel/coolant interactions in LWRs.potential coatings. ATF).An ATF that is being pursued byThe analyses were performed with Westinghouse is uranium-nitride (UN)the TRITON lattice code for a detailed with fully enriched N-15 to mitigate themodel of a reference 17x17 Westing-absorption penalty of N-14.However,house fuel assembly and the fuel was UN adversely interacts with the coolantassumed to be fully enriched N-15.in LWRs, and this study examined theInitial studies assumed 20 m thick-impact on reactor performance andness for candidate coatings proposed safety characteristics of coating UNby LANL.The coatings were applied fuel pellets to mitigate the fuel/coolantto the surface of the pellet and the fuel interactions in LWRs.Several candidatespellet outer radius and cladding radii proposed by LANL for the coatings werewere fixed at the reference values to analyzed.Initial studies assumed 20 mfacilitate insertion in existing PWRs.thickness for the coatings applied to theCycle length, discharge burnup and surface of the pellet. 120 2020|AFC ACCOMPLISHMENTS'