Qom - Iranian Underground Enrichment Facility

The large excavation is notable for the extensive structural lattice which appears to be rebar [reinforcing bar], the steel bar used in reinforced concrete construction. While this excavation might be interpreted as an entrance to a much larger underground facility, upon reflection it seems far too large - 120 meters x 45 meters / 400 feet x 150 feet - for this function. This roughly football field sized excavation is roughly consistent in volume with the larger lobe of the spoils pile [which is not in evidence in the 2005 image], which suggests that this spoils pile reflects this excavation, and that there is no larger underground tunnel complex. With an area of somewhat greater than 5,000 square meters, based on the floor space and number of centrifuges at the other Iranian enrichment facility at Natanz, this complex is consistent in size with the 3,000 centrifuges reported by the 25 September 2009 US Government background briefing.

Globalsecurity.org