[en] We present an investigation of homogenisation techniques in criticality safety analyses of partly assembled fuel rod lattices as they appear in connection with fuel fabrication and repair. These techniques allow us to continuously and uniformly vary the moderator-to-fuel ratio over defined zones of the fuel assembly in order to tune the moderation state to optimum moderation leading to maximum reactivity. Two different homogenisation methods are compared. The first method involves computation of cell-weighted cross sections of the empty lattice cells followed by homogenising the material of the occupied and unoccupied lattice cells in the considered lattice zone. For the second method, the moderator-to-fuel ratio is tuned to the value defined by the number of occupied and unoccupied lattice positions by adapting the pitch of the fuel lattice accordingly. Comparing the results obtained with the two homogenisation methods to the results obtained for discretely modelled fuel lattice configurations demonstrates that both homogenisation methods are suitable for bounding criticality safety analyses of partly assembled fuel assemblies. Models with two zones prove to be sufficient in this context, where the outer lattice positions are all occupied with fuel rods to minimise neutron leakage, and the interior of the fuel assembly is tuned to a state of optimum moderation. Since the homogenisation methods are easy to use and minimise the analysis effort, they are well-suited for criticality safety analyses of partly assembled fuel rod lattices. (authors)