November 23, 2012

The Iranian Nuclear Program: Timelines, Data, and Estimates V5.0

This assessment is version 5.0 of a recurring analysis of Iran’s nuclear program.


Additional Centrifuge Installation

  • Iran increased its enrichment capacity by installing additional centrifuges at its declared sites between August and November 2012. The hardened Fordow facility is now at maximum capacity (2,784 centrifuges). Of the 2,784, 696 centrifuges are currently enriching at Fordow and 696 are ready to begin enriching immediately. The IAEA also noted the addition of first-generation and advanced centrifuges, the latter undergoing testing, at the Natanz facility.

Increasing Enriched Uranium Stockpiles

  • Iran continues to produce low- (<5%) and medium-enriched (near 20%) uranium at historically high rates. It has now allocated roughly 40% of its medium-enriched uranium for conversion to reactor fuel plates; only a small fraction of the allocated material, however, has been packaged into fuel plates and placed into a reactor core as of August 2012.   

Parchin Facility Inspection

  • Iran continues to deny the IAEA access to the Parchin facility, where the agency believes Iran conducted experiments related to nuclear weapons development. The IAEA noted that, even if it is given access to the site, its ability to “conduct effective verification will have been seriously undermined” by physical disruption and sanitization undertaken by Iran at the facility in 2012.


  • Iran continues to stonewall the IAEA regarding its weaponization activities. The agency reiterated its assessment of Iran’s work on nuclear weapons development: “the information indicates that, prior to the end of 2003 the activities took place under a structured program; that some continued after 2003; and that some may still be ongoing.”

Arak Reactor Timeline

  • Iran told the IAEA that it will begin operating the Arak heavy water reactor later than previously planned. The reactor, now scheduled for an early 2014 launch, will provide Iran with a separate pathway to acquiring fissile material for nuclear weapons in the form of weapons-grade plutonium.   




Iran can produce one bomb’s worth of fissile material faster than it likely can deploy a functioning nuclear device. Tracking Iran’s uranium enrichment activities now addresses only Iran’s intentions and the size of its projected arsenal.

Obtaining fissile material in the form of weapons-grade uranium or plutonium is the most technically demanding step in acquiring a nuclear weapons capability. Designing an explosive device (consisting of non-nuclear components) and a delivery system for the device are comparatively less technically challenging. Those efforts can also proceed parallel to enrichment.

Iran has the infrastructure and material to produce weapons-grade uranium. It has enough enriched uranium to produce fuel for six nuclear weapons after conversion to weapons-grade levels. Its expanding enrichment activities have significantly reduced the time required for it to produce weapons-grade uranium. The key accelerants for this shrinking timeline have been its growing stockpiles of low- and medium-enriched uranium, which is 90% of the way to weapons-grade uranium, and an increasing number of centrifuges enriching.

Nuclear Program Expansion

Iran will likely have enough near-20% enriched uranium to rapidly produce fissile material for 2 nuclear weapons by late 2013 or early 2014.

Iran has installed many more centrifuges at the hardened Fordow facility than are now actually spinning, providing a reserve and/or surge capacity that will be difficult for Israel to destroy.

The installation of 2,088 additional centrifuges at Fordow since summer 2012 gives Iran the ability to:

  • produce near-weapons grade uranium (20% enrichment level) in larger quantities faster, providing rapidly-convertible feedstock for a small arsenal of nuclear weapons;

  • convert near-weapons grade uranium into nuclear weapons fuel in a shorter amount of time.

Iran’s uranium enrichment is at historically high rates despite increasing sanctions and damage to the Iranian economy.

Iran told the International Atomic Energy Agency (IAEA) that it plans to begin operating the Arak heavy water reactor in early 2014 (it had previously planned commencement for mid-to-late 2013). This reactor will be capable of producing two warheads’ worth of weapons-grade plutonium per year once operational.

Breakout Timelines

Time needed to produce fuel for 1 nuclear weapon:

  • Iran needs 3.6 months to produce 25 kg of weapons-grade uranium and 1.9 months to produce weapons-grade uranium at the buried Fordow and pilot Natanz enrichment facilities.* It can cut these times significantly using the centrifuges installed but not yet operating at the Fordow facility.

  • Iran needs 4-10.5 weeks to produce 25 kg of weapons-grade uranium and 1.5-5 weeks to produce 15 kg of weapons-grade uranium at the main Natanz enrichment facility.* The higher end of the range accounts for a three-step conversion process.

Estimates of the time Iran needs to build a nuclear device to use this fissile material are generally longer than the timelines above.

The existence of undeclared (covert) enrichment sites would have a significant impact on breakout estimates.

Evidence of significant Iranian enrichment beyond 20% will strongly suggest not only that the decision to weaponize has been made, but also that the Iranians believe they have (or will shortly have) a viable warhead.

*All enriched uranium figures are given in terms of solid uranium (where 1 kg uranium hexafluoride is equal to ~0.67 kg elemental uranium). Estimates assume Natanz and Fordow are used with the operational capacity reflected in the November 2012 IAEA report. Iran may need 15-25 kg of weapons-grade uranium for an implosion-type bomb design depending on its level of technical ability (high technical ability would require less material). See pages 18, 19, and 22 for further detail.  

This product is an exposition of the technical data contained in numerous International Atomic Energy Agency (IAEA) reports informed by the discussions of experts in the field of nuclear proliferation. It is a work in progress in that it will be revised continuously based on new information from the IAEA reports and other sources and on feedback from readers. We welcome your informed commentary on the technical considerations presented in this document. Please send your comments, with references to source-date or documentation, to [email protected].