We consider three main target facilities which if attacked could either destroy the program or delay it for some years. After analyzing the targets a damage criteria is suggested measured by the blast pressure of the weapon used. It would be safe to assume a required 5 to 10 psi which would be sufficient to either destroy or damage the facility for a long period of time. Care must be taken not to overkill for this could practically double the strike force required.
- 10 psi : Reinforced concrete buildings are severely damaged or demolished. Most people are killed.
- 5 psi : Most buildings collapse
- 3 psi : Residential structures collapse.
We then work out how many bombs must be dropped to cover a certain area above and below ground. To be on the safe side, we consider weapons that penetrate hard and deeply buried targets (HDBTs). The Natanz facilty for instance is reported to have underground facilities where the centrifuges are installed for uranium enrichment.
Natanz facility apparently covers some 670,000 sq ft in total, the Fuel Enrichment Plant (FEP) complex was built some 8 meters-deep into the ground and protected by a concrete wall 2.5 meters thick, itself protected by another concrete wall. By mid-2004 the Natanz centrifuge facility was hardened with a roof of several meters of reinforced concrete and buried under a layer of earth some 75 feet deep. It is reported that this facility will eventually house some 50,000 centrifuges.
The Esfahan Nuclear Technology Center (ENTC) is an Industrial-Scale Uranium Conversion Facility (UCF). The U3O8 is transported to ENTC to convert it to UF6 (Uranium Hexafluoride). The area of the buildings is estimated to be around 100,000 sq ft. and are above ground.
The Arak Facility covers an area of approximately 55,000 sq ft and contains the Heavy Water Reactor and a set of cooling towers. There are no underground facilities reported in this complex.