Advanced fuel designs have been developed with the aim of improving fuel cycle efficiency. With this idea, moderator distribution in boiling water reactor fuel assemblies has been improved. The current work analyzes two 9×9 fuel assemblies with different inner channel designs. The first design corresponds to an actual assembly, whereas the second is proposed with the aim of making comparisons between their performances. The former design is an internal parallelepipedal water channel, and the latter is an internal cylindrical water channel whose diameter is equal to one side of the first. It is observed that the former assembly has a better burnup. Reloads for Laguna Verde Nuclear Power Plant are simulated for each design. Better operational limits are obtained by using the latter assembly. The increase in the amount of water yields a more uniform burnup, although as shown in this study, this fact does not necessarily improve the plant operational limits.