<p>A series of reactive flow modeling scenarios were developed using the software TOUGHREACT to: (1) investigate the effect of the number of faults and their spacing on ore-forming fluid flow and uranium mineralization; and (2) examine the sandstone permeability threshold for the formation of unconformity-related uranium (URU) deposits. The modeling results indicate that uranium mineralization tends to occur in the basement and below the downwelling zones of overlying basinal fluid circulation cells, where oxidizing basinal fluids percolate across the unconformity and react with upwelling, reducing basement brine. Thus, the basinal fluid circulation patterns in the sandstone aquifer, controlled by aquifer permeability, number of faults and their spacing, are critical in determining the formation and distribution of URU deposits. When the sandstone layer is more permeable, the simulated uranium deposits become larger in size, and vice versa. If the sandstone permeability is &lt; 3 × 10^-14 m², no significant URU deposits are formed, regardless of the number of faults and their spacing. Therefore, 3 × 10^-14 m² is proposed as the sandstone permeability threshold, corresponding to the physiochemical parameters and model dimensions considered in this study. This threshold can be used as a complementary indicator to other traditional geological and geochemical parameters when assessing the potential of a region for hosting URU deposits. However, attention should be given to other physical properties and geothermal conditions of the region.</p>