Calculations of the effective neutron multiplication factor of critical and subcritical infinitely long cylinders of aqueous solutions of fissile materials for various configurations of water and concrete reflectors are presented. These results provide a basis for investigating the criticality of intersecting pipes with similar reflectors. An infinitely long central cylinder, with up to four intersections within each 0.46-m increment of length, was examined, and a method for evaluating the nuclear criticality safety of these configurations is given and a margin of subcriticality recommended.