Preliminary Study on Fuel Enrichment Increase for Accident Tolerant Fuel Concept

Conclusions: For some ATF candidate materials, increasing ²³⁵U enrichment could be an important solution to balance the safety performance and cost. • In order to match the margin in mechanical design, FeCrAl cladding should have almost same thickness with Zircaloy of conventional PWR fuel. In that case the enrichment should be increased by 0.96% to match the cycle length of reactor core. • For a 13×13 fuel rod array configuration, under the limit of 20% enrichment, requirement of UO₂ and UN kernel diameters are 730μm and 650μm, when the packing fraction is set to be 45%; while if the diameter is set to be 700μm, packing fraction of UO₂ and UN kernel should reach at 50% and 36%. • Taking no account of fuel assembly fabrication and spent fuel disposal, when the enrichment reaches at 20%, total cost of four components (including natural uranium, conversion, enrichment and depleted uranium disposal) increases about 17% compared with 5% enriched fuel. • For the ATF development, general assessment need to be considered from aspects of fuel cost, core design, fuel design, licensing issue, influence on fuel cycle, etc., in order to evaluate the feasibility of increasing fuel enrichment.