Nuclear Fuel Batch Optimization for Extra Long Equilibrium Core Design of APR-1400

This paper proposes a core design methodology with a systematic approach to nuclear fuel batch optimization. The proposed methodology consists of three major steps: evaluation of core average enrichment and the number of burnable absorber (BA) rods in a core, determination of batch size and batch enrichments, and loading pattern (LP) search. The proposed methodology is applied to design one initial core model and five equilibrium core models. All models satisfy design constraints. For equilibrium core models, the number of feed fuel assemblies (FAs) vary from 92 to 128 FAs, firstly to determine the enrichment requirements necessary to meet 24-month cycle length, and secondly to investigate a relationship between fuel cycle cost and batch size. The results demonstrate that 24-month equilibrium fuel cycle is possible for a number of feed FAs greater than 116 because of the limitations [1] on maximum fuel enrichment up to 5 w/o and maximum burnup of 60 MWD/kgU. Furthermore, levelized fuel cycle cost (LFCC) calculations for 24-month equilibrium core models of APR-1400 show that more than 116 feed FAs of APR-1400 is less economic than 18-month cycle length of OPR-1000 or 19-month cycle length of APR-1400.