Can we define an hexagonal mesh which allow us to obtain tallies over hexagonal lattices easily
hexagonal meshes are not available in OpenMC. you have to use distribcell command to tally for hexagonal meshes.
please refer to this thread for further details of distribcell usage
https://groups.google.com/forum/#!topic/openmc-users/PiTNpttWXOA
hope that helps.
Khurrum