July 10, 2013

The Iranian Nuclear Program: Timelines, Data, and Estimates V7.0

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

  • The dual-track policy of pressure and engagement is failing to prevent Iran from building a robust nuclear weapons capability. There is increasing risk that Iran will be able to produce nuclear weapons fuel undetected or, assuming detection occurs, on a timeline that would prevent successful intervention.

  • International Atomic Energy Agency (IAEA) inspectors observed that Iran has installed almost 700 IR-2m centrifuges at the Natanz enrichment facility. These machines have an output rate several times greater than first-generation centrifuges. The deployment of IR-2m centrifuges in significant quantities will drastically reduce the time required for weapons-grade (~90% enriched) uranium production.

  • Since February 2013, Iran has also added nearly 900 more first-generation centrifuges at Natanz. The addition of more than 6,000 centrifuges at the Natanz and Fordow facilities over the last 12 months is an indication that sanctions and interdiction efforts have not curbed Iran’s ability to produce centrifuges in significant quantities. Increases in the quantity and quality of centrifuges have continued to further drive down conversion times for the production of nuclear weapons fuel.

  • Iran has produced enough enriched uranium with which it can produce nuclear weapons fuel for at least half a dozen nuclear weapons. Iran has produced 6,063 kg of reactor-grade (<5% enriched) uranium. Some of this material, which is three-quarters of the way to bomb fuel, has been converted into 219 kg near-weapons grade (~20% enriched) uranium; only a small fraction of this material has been used to fuel a research reactor. The remaining quantity of ~20% enriched uranium can be rapidly converted to fuel for one weapon. 

  • Iran is continuing work on a heavy water reactor that will be capable of producing plutonium for two weapons every year. IAEA inspectors recently observed the presence of an uninstalled reactor vessel at the Arak facility. Iran has told the IAEA that the reactor will be operational between July and September 2014.

  • The IAEA maintains that it has a credible, corroborated body of information indicating that Iran continued activities related to the development of a nuclear explosive device after 2003 and that some activities may still be ongoing.



  • Obtaining fissile material in the form of weapons-grade uranium or plutonium is the most technically demanding step in developing a nuclear weapon. The parallel steps of designing an explosive device and a delivery system are comparatively less technically challenging.

  • Iran, due to its enrichment program expansion since 2009, can now produce one bomb’s worth of fissile material faster than estimates of the time needed to build a nuclear device to mate the material with. Potential timelines for weapons-grade uranium production could contract further due to increasing centrifuge numbers and types. Iran’s low-enriched uranium stockpile is currently adequate for fueling a small arsenal of nuclear weapons after further conversion to weapons-grade.  

  • Enrichment up to weapons-grade uranium (~90% enriched) is one key indicator of Iranian weaponization. Evidence of enrichment beyond research reactor-grade uranium (~20% enriched), material that is 90% of the way to weapons-grade, 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 device. 


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 15 kg weapons-grade uranium at the hardened Fordow enrichment facility.* It can cut these times significantly using the centrifuges installed but not yet operating at the Fordow facility.

Iran needs 4-10 weeks to produce 25 kg of weapons-grade uranium and 1-5 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.

*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 February 2013 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).

This product is an exposition of the technical data contained in numerous 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].