January 31, 2013

Iran's Centrifuge Plans Would Undermine U.S. Policy Assumptions

Iran has announced its intention to expand its ability to enrich uranium rapidly by installing advanced centrifuges at the Natanz Fuel Enrichment Plant. If Iran carries through on this declaration it will undermine one of the core assumptions of current U.S. policy aimed at preventing Iran’s acquisition of nuclear weapons—namely, that the U.S. will detect the start of the process of enriching to weapons-grade uranium in time to take meaningful action.

Iranian officials recently notified the International Atomic Energy Agency (IAEA) that they intend to fill a unit at the underground Natanz enrichment facility with IR-2m centrifuges.[i] A unit at Natanz consists of 18 cascades of approximately 170 centrifuges each; a fully outfitted IR-2m unit would hold just over 3,000 centrifuges.[ii] These second-generation machines have an output rate several times greater than the IR-1 machines Iran currently uses for its enrichment program.[iii]

The use of IR-2m machines would significantly reduce the time required for Iran to acquire weapons-grade uranium. Three thousand IR-1 centrifuges at Natanz can convert near-20% enriched uranium into one weapon’s worth of highly-enriched uranium in just under one month.[iv]  The same conversion using 3,000 of the advanced IR-2m centrifuges would take just 5-8 days.[v] This shortened interval has significant policy implications. In 2011, Pentagon spokesman George Little said that IAEA inspectors—who make periodic visits to Natanz but are not permanently stationed there—could detect such a move, and that “we would retain sufficient time under any such scenario to take appropriate action.”[vi] If the time between inspector visits is longer than a week, would we be able to receive warning regarding the key indicator of weaponization?

This technical upgrade has the potential to upend one of the most basic assumptions underpinning our standing policy to prevent the emergence of a nuclear Iran: that we will detect an Iranian move to enrich to weapons-grade in time to intervene. The prospect of operational IR-2m centrifuges, and with them an Iranian capability to produce weapons fuel between inspectors’ visits at known facilities or within days at smaller covert facilities, greatly increases the likelihood of policy failure.      

[i] George Jahn, “Iran says it will speed up nuclear program,” The Associated Press, January 31, 2013, http://www.google.com/hostednews/ap/article/ALeqM5jPHLK4rK7Md1f42qK3DZwSHvQM_A?docId=82f8ffeeab294344bc57c3df6f719acc.
[ii] The IAEA has previously observed IR-2m machines at Natanz and reported that small numbers of these machines have been intermittently fed with natural uranium. See http://www.iaea.org/Publications/Documents/Board/2012/gov2012-55.pdf.
[iii] The Institute for Science and International Security (ISIS) has noted that the IR-2m is designed to enrich at a rate of 5 separative work units (SWU) per centrifuge, per year. Iran is currently operating its IR-1 machines at around 0.9 SWU per centrifuge, per year.  ISIS has estimated that the average output of these machines in production cascades would be about 3-4 SWU per centrifuge, per year. See David Albright and Christina Walrond, “Iran’s Advanced Centrifuges,” ISIS, October 18, 2011, http://isis-online.org/isis-reports/detail/irans-advanced-centrifuges/.
[iv] This estimate assumes 193 kilograms of 19.75% enriched uranium are converted into 25 kilograms 90% enriched uranium with a tails assay rate of 9.3% and SWU rate of 0.9 per centrifuge, per year.
[v] This estimated range assumes 193 kilograms of 19.75% enriched uranium are converted into 25 kilograms 90% enriched uranium with a tails assay rate of 9.3% and SWU rate of between 3.0 and 5.0 SWU per centrifuge, per year.
[vi] Thom Shanker, “Aides Qualify Panetta’s Comments on Iran,” The New York Times, December 20, 2011, http://www.nytimes.com/2011/12/21/world/middleeast/pentagon-officials-qualify-panettas-iran-remarks.html