Cryogenic distillation is an attractive method for the hydrogen isotopic separations required in fusion fuel cycles. The theoretical and practical aspects of designing and constructing such systems are well established. Practical considerations in the design of systems are presented and applied to the Isotope Separation System (ISS) at the Tritium Systems Test Assembly (TSTA), as well as systems of distillation columns that might be used for a reactor such as the Tokamak fusion Core Experiment (TFCX) and the recovery of breeding blanket product.