b'2.6 PERFORMANCE ASSESSMENTAnalysis of Fuel Utilization for MicroreactorsPrincipal Investigator: Arantxa CuadraTeam Members/Collaborators: Cihang LuA n assessment of the viabilityhexagonal fuel blocks surrounded and potential attractivenessby hexagonal beryllium reflector of advanced nuclear fuelsblocks and 12 control drums. must include consideration of howEmploying traditional uranium proposed concepts will impactoxycarbide (UCO) Tristructural the nominal reactor performanceIsotropic (TRISO) fuel compacts and safety characteristics. Thiswith a U-235 enrichment of 19.75 assessment includes neutronicswt.% and a fuel to compact volume analyses to evaluate the impact onratio of 4.9%, the baseline HP-MR is performance parameters (e.g., cyclecapable of generating approximately length/burnup, power distributions,2 MW thermal for ~8 years, with a etc.), safety-related characteristicsdischarge burnup of ~13 GWd/tU. (e.g., reactivity and control coef- Additionally, eight UN cases, with ficients/worths, kinetics parameters,solid fuel pellets and TRISO fuel etc.), and performance in a broadcompacts, and different levels of spectrum of transient and accidentnitrogen-15 (N-15) enrichment, were scenarios. Over the past decade,modeled to better understand the Brookhaven National Laboratorytrade-off between U-235 enrichment (BNL) has developed and bench- and N-15 enrichment. It is important marked a scoping methodology toto assess whether the reduction perform an initial screening of thein U-235 that is anticipated from performance and safety of candidatethe use of UN in pellet form would advanced fuel concepts, in supportcounteract the disadvantages of of the Advanced Fuels CampaignN-15 enrichment, which is a costly and its predecessors, recognizingprocess at the moment. The U-235 that the fuel and reactor are anenrichment of the eight UN fuel intimately linked system. options was adjusted such that the fuel cycle length remained Project Description: unchanged (8-year lifetime).Advanced fuels, including ceramic fuels, have the potential to fulfill theAccomplishments:needs of multiple reactor designs.The impact of retrofitting the This study assesses the impact ofbaseline HP-MR with eight UN fuel using uranium nitride (UN) fueloptions was assessed, compared on the neutronic performance ofwith the baseline UCO TRISO fuel. a thermal-spectrum microreactor,Due to the higher mass density of specifically the Heat-Pipe Microre- UN (13.46 g/cm3 with a uranium actor (HP-MR) designed by Argonnemass density of ~ 12.7 g/cm3) than National Laboratory. Cooled by heatUCO (10.52 g/cm3, with a uranium pipes and moderated by yttrium- mass density of ~ 9.4 g/cm3), the hydride, HP-MR consists of 30UN TRISO options required a lower 124 2023|AFC ACCOMPLISHMENTS'