A model is described which permits conservative homogenization of a random distribution of low-enriched UO2 pellets in a low-enriched UO2 powder and water mixture. The model is used with a Monte Carlo criticality code to demonstrate the criticality safety of General Electric Model BU-5 bulk uranium shipping containers which are used for the transportation of unirradiated uranium compounds in the form of powder or pellets, moderated to any degree and enriched to a maximum of 4 wt% in the 235U isotope.