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


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

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

  1. 1. The Iranian Nuclear Program Timelines, Data, and Estimates Maseh Zarif Deputy Director and Iran Team Lead AEI Critical Threats Project Version 5.0 NOVEMBER 2012 Current as of NOV 21 2012 using data from IAEA report dated NOV 16 2012 Copyright © 2012 by the AEI Critical Threats Project
  2. 2. November 2012 International Atomic Energy Agency (IAEA) FindingsAdditional 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.Weaponization 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. Page 2
  3. 3. Status of Near-20% Enriched UraniumIran has enough near-20% enriched uranium with which to produce weapons-gradeuranium (WGU) for one warhead. Some of this material is currently stored in oxidepowder form, which can be converted back into a gas for weapons-grade enrichment. NEAR-20% ENRICHED URANIUM 141 kg needed to produce one warhead’s worth of WGU 156 kg produced as of November 2012 IAEA report (see pie chart for breakdown) 151.5 kg available in gas or oxide powder form (allocated for use in fuel plates for Tehran Research Reactor) 3.4 kg 1.1 kg Converted into U3O8 fuel Enriched down to <4% plates and placed into or irradiated in reactor core (as of August 2012) 52 kg 99.5 kg Fed into process for Stored as enriched conversion to U3O8 uranium gas (available for WGU (available now for WGU production after re- production) conversion to gas form)* Total near-20% enriched uranium produced: 156 kg*Methods for converting near-20% material in U3O8 form back into a gas “are standard processes in the nuclear industry and Iran uses them as part of itsuranium ore processing.”1 The conversion can be done using specialized facilities and can be accomplished in “days to weeks.”2 The near-20% LEU canonly be classified as unusable in a breakout once the fuel assemblies containing the U3O8 are inserted and irradiated in a reactor core. Only a smallfraction of Iran’s near-20% LEU in the form of U3O8 has been manufactured into fuel assemblies and placed into or irradiated in a reactor core (3.4 kg).1) Gregory Jones, “Fueling the Tehran Research Reactor: Technical Considerations on the Risks and Benefits,” NPEC, October 12, 2009. Page 32) Ibid.
  4. 4. Key Points IRAN’S ENRICHMENT CAPABILITIES ARE NO LONGER THE PRIMARY BOTTLENECK IN A NUCLEAR BREAKOUT SCENARIOIran can produce one bomb’s worth of fissile material faster than it likely can deploy afunctioning nuclear device. Tracking Iran’s uranium enrichment activities now addresses onlyIran’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. Page 4 Copyright © 2012 by the AEI Critical Threats Project
  5. 5. Nuclear Program ExpansionIran will likely have enough near-20% enriched uranium to rapidly produce fissilematerial for 2 nuclear weapons by late 2013 or early 2014.Iran has installed many more centrifuges at the hardened Fordow facility than are nowactually spinning, providing a reserve and/or surge capacity that will be difficult forIsrael to destroy.The installation of 2,088 additional centrifuges at Fordow since summer 2012 gives Iranthe 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 anddamage to the Iranian economy.Iran told the International Atomic Energy Agency (IAEA) that it plans to begin operatingthe Arak heavy water reactor in early 2014 (it had previously planned commencementfor mid-to-late 2013). This reactor will be capable of producing two warheads’ worth ofweapons-grade plutonium per year once operational. Page 5
  6. 6. Breakout TimelinesTime 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 aregenerally longer than the timelines above.The existence of undeclared (covert) enrichment sites would have a significant impacton breakout estimates.Evidence of significant Iranian enrichment beyond 20% will strongly suggest not onlythat the decision to weaponize has been made, but also that the Iranians believe theyhave (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 kgelemental uranium). Estimates assume Natanz and Fordow are used with the operational capacity reflected in the November2012 IAEA report. Iran may need 15-25 kg of weapons-grade uranium for an implosion-type bomb design depending on itslevel of technical ability (high technical ability would require less material). See pages 18, 19, and 22 for further detail. Page 6
  7. 7. Iran has outfitted the hardened Fordow enrichment facility with 2,784 IR-1centrifuges. This expansion gives Iran the capacity to produce near-20%enriched uranium at a faster rate and the means to convert that stockpileto weapons-grade uranium (WGU) more rapidly in a deeply buried site. Time needed to produce WGU Time needed to produce near- for 1 warhead from near-20% 20% enriched uranium feed enriched uranium at Fordow for WGU for second warhead* Using 696 centrifuges currently enriching 4.7 MONTHS 14 MONTHS Using 1,392 centrifuges currently enriching and under 2.4 MONTHS 8.6 MONTHS vacuum Using all 2,784 centrifuges available 1.2 MONTHS 4.7 MONTHS*Assumes constant production of near-20% enriched uranium at smaller pilot facility at Natanz Page 7
  8. 8. Iran’s Declared 3.5% Enriched Uranium Production at Natanz Assessment: Stuxnet derailed the 2009 Iranian effort to expand enrichment capability for roughly one year, but the enrichment expansion effort recovered in mid-2010. Neither direct actions nor sanctions have had a visible effect on the enrichment program. Even the Stuxnet success does not appear to have derailed the steady growth of the enriched uranium stockpile. Iran is running its highest number of centrifuges and production rates since the enrichment program began. It has produced enough enriched uranium since 2009 to fuel a small arsenal of nuclear weapons after conversion to weapons grade. New U.S./ Iranian Centrifuges Centrifuges 3.5% LEU Stuxnet Scientist UN/EU enriching not produced Launched Killed sanctions enriching 10000 6000 9000 5000 8000 7000 4000 6000 Kilograms LEU # centrifuges 5000 3000 4000 2000 3000 2000 1000 1000 0 0 Jan-09 Apr-09 Jul-09 Oct-09 Jan-10 Apr-10 Jul-10 Oct-10 Jan-11 Apr-11 Jul-11 Oct-11 Jan-12 Apr-12 Jul-12 Oct-12Enrichment data source: IAEA Page 8 Copyright © 2012 by the AEI Critical Threats Project
  9. 9. Near-20% Enriched Uranium Production and Projected Growth at Fordow/Natanz Amount needed for: 705 ~20% enriched uranium production enough to produce WGU for three nuclear bombs by 4 564 weapons Iran will have produced 282 kg late 2013/early 2014. Iran would ~20% enriched uranium by late need to begin enriching graduallyKilograms 19.75% LEU 2013/early 2014 under steady-state in installed Fordow cascades to 3 423 conditions--enough to produce meet this threshold. weapons WGU for two nuclear bombs 282 designed with a low level of 2 technical capability. weapons 141 1 weapon 156 kg (as of NOV 2012) 0 May-12 Jul-12 Oct-12 Jan-13 May-13 Jul-13 Oct-13 Jan-14BLACK: Reported productionRED: Steady-state enrichment (a)GREEN: Gradual enrichment expansion in available centrifuges at Fordow (b)PURPLE: Rapid enrichment expansion at Fordow (c)*The two lines for each colored scenario represent a range based on different calculations of demonstrated centrifuge efficiency.(a) 1,024 centrifuges currently enriching (2 cascades with 328 total IR-1 centrifuges at PFEP and 4 cascades with 696 total IR-1 centrifuges at Fordow)(b) Same as (a) but Iran begins turning on 2 additional cascades at Fordow every three months in DEC.(c) Iran begins enriching in the 4 additional cascades under vacuum at Fordow in DEC. It will begin enriching in the 8 remaining cascades in JAN 2013. Page 9 Copyright © 2012 by the AEI Critical Threats Project
  10. 10. Key Upcoming Events 12/15/2013 Approx. date by which Iran—at current rates—will produce enough near-20% enriched uranium to convert to WGU for a second warhead 1/22/2013 - 2/12/2013 4/23/2013 - 5/14/2013 7/30/2013 - 8/20/2013 IAEA Inspection Window IAEA Inspection Window IAEA Inspection Window 12/1/2012 1/1/2013 2/1/2013 3/1/2013 4/1/2013 5/1/2013 6/1/2013 7/1/2013 8/1/2013 9/1/2013 10/1/2013 11/1/2013 12/1/2013 1/1/2014 Italicized dates are estimates; bold dates are fixed Listed inspection windows are approximate. The IAEA may be11/29/2012 3/4/2013 6/3/2013 9/9/2013 conducting inspections outside of these windows.IAEA BOG IAEA BOG IAEA BOG IAEA BOG meets meets meets meets 2/22/2013 5/24/2013 8/30/2013 IAEA Report IAEA Report IAEA Report IAEA BOG = International Atomic Energy Agency Board of Governors Page 10 Copyright © 2012 by the AEI Critical Threats Project
  11. 11. Making an Atomic Bomb (Concept) Acquire Weapons-grade Parallel processes Design Parallel processes Acquire delivery Uranium warhead vehicle Centrifuge Acquire weapon cascade design LEU gas Fed back into produces UF6 gas Shahab-3(3.5% U-235) 19.75% U-235 missile Fed back into produces Develop detonator technology Centrifuge Centrifuge cascade Two-step cascade Test design uranium Fed through produces and engineering enrichment then UF6 gas process UF6 gas 0.7% U-235 90% U-235 Build weapon Converted to Processed into Test weapon Mate warhead with delivery vehicle Natural uranium High-enriched elemental uranium (Process complete) solid metal (90% U-235) Page 11 Copyright © 2012 by the AEI Critical Threats Project
  12. 12. Making an Atomic Bomb (Status as of NOV 2012) ay ay w Acquire Weapons-grade Design Acquire delivery w ne Parallel processes Parallel processes r r de warhead vehicle de Uranium Do Un Un Centrifuge Acquire weapon cascade design ay Shahab-3 w ne ne ne LEU gas Fed back into produces UF6 gas r (3.5% U-235) 19.75% U-235 missile Do Do de Do Un Fed back into produces NB: All estimates of Iran’s Develop detonator ay nuclear status and technology w Centrifuge capabilities assume that Centrifuge r there are no clandestine de cascade cascade facilities, and that the Un IAEA has full access to all Test design Fed through produces declared facilities. The and engineering first assumption is impossible to verify. The d then te second assumption is or ne UF6 gas known to be false. UF6 gas ep 0.7% U-235 Do 90% U-235 tr Build weapon d te No or Converted to Processed ep into tr No Mate warhead with g ne Test weapon in g d in Do te delivery vehicle ar or Natural uranium ar ep ep High-enriched (Process complete) ep Pr tr elemental uranium Pr No solid metal (90% U-235) Page 12 Copyright © 2012 by the AEI Critical Threats Project
  13. 13. Why Enrichment Accelerates at Higher Concentration of U-235 Centrifuge 1,373 kg cascade 116 kg LEU gas Fed back into produces UF6 gas (3.5% U-235) 19.75% U-235 559 SWU The work and time required to Fed back into 37 days enrich uranium from its natural produces concentration (0.7%) to 3.5% Centrifuge 5,060 SWU 115 SWU Centrifuge LEU is an order of magnitude cascade 331 days 8 days cascade greater than that required to enrich 20% LEU to weapons- Fed through produces grade concentrations (~90% U- 235). 14,187 kg 15 kg That is because centrifuges UF6 gas UF6 gas 0.7% U-235 90% U-235 must spin more than 14,000 kg of uranium ore to produce Processed Converted to 1,373 kg of 3.5% LEU, but only into 116 kg of 20% LEU to produce 15 kg of weapons-grade uranium. Natural uranium High-enriched elemental uraniumSWU = Separative work unit, a measure of the amount of effort solid metal (90% U-235)required to process nuclear material. The SWU requirement isused to determine the time needed to enrich uranium with a givennumber of centrifuges operating at a given efficiency. Page 13 Copyright © 2012 by the AEI Critical Threats Project
  14. 14. Iran’s Declared Uranium Enrichment FacilitiesFordow Fuel Enrichment Plant (FFEP)As of NOV 10 2012: 696 IR-1 centrifuges producing near- 20% LEU 696 IR-1 centrifuges under vacuum and 1392 IR-1 centrifuges not enriching Facility producing near-20% low- enriched uranium (LEU) 464.3 kg 3.5% LEU converted to 64 kg near-20% LEU 225 kg 3.5% LEU remaining from Natanz stockpile sent here*Notes* Calculated estimated based on 145amount IAEA reported has beentransferred from Natanz to Fordow km Natanz Fuel Enrichment Plant (FEP) As of NOV 2012: 9156 IR-1 centrifuges producing <5% LEU 1258 additional IR-1 centrifuges not enriching Facility producing 3.5% enriched LEU Pilot Fuel Enrichment Plant (PFEP) 4992 kg 3.5% LEU produced here As of NOV 2012: 328 IR-1 centrifuges producing near- 20% LEU 176 IR-2m and 176 IR-4 centrifuges installed and intermittently fed Facility producing near-20% LEU 788.6 kg 3.5% LEU converted to 92 kg ` near-20% LEU Unknown kg 3.5% LEU stored here Page 14 Copyright © 2012 by the AEI Critical Threats Project
  15. 15. Natanz Enrichment FacilitiesPilot Fuel Enrichment Plant (PFEP)As of NOV 2012: 328 IR-1 centrifuges producing near- 20% LEU Natanz Fuel Enrichment Plant (FEP) 176 IR-2m and 176 IR-4 centrifuges As of NOV 2012: installed and intermittently fed 9156 IR-1 centrifuges producing <5% Facility producing near-20% LEU LEU 788.6 kg 3.5% LEU converted to 92 kg 1258 additional IR-1 centrifuges not near-20% LEU enriching Unknown kg 3.5% LEU stored here Facility producing 3.5% enriched LEU 4992 kg 3.5% LEU produced here Underground halls under construction FEB 2003 Page 15 Copyright © 2012 by the AEI Critical Threats Project
  16. 16. Fordow Enrichment Facility: Status and Construction Image taken SEP 14 2012 Image from MAR 24 2005 (Google Earth)Pleiades, Apollo Mapping Areas covered in 2005 appear as entrances to New above- Fordow Fuel Enrichment Plant (FFEP) underground facilities in 2009 ground As of NOV 10 2012: facility 696 IR-1 centrifuges producing near- appears 20% LEU between 696 IR-1 centrifuges under vacuum and 2005 and 1392 IR-1 centrifuges not enriching 2009 Facility producing near-20% low- enriched uranium (LEU) Ridgeline rises 464.3 kg 3.5% LEU converted to 64 kg roughly 200 feet near-20% LEU from entrances 225 kg 3.5% LEU remaining from Natanz stockpile sent here* to peak. Notes * Calculated estimated based on amount IAEA reported has been transferred from Natanz to Fordow Image from NOV 24 2009 (Google Earth) Page 16 Copyright © 2012 by the AEI Critical Threats Project
  17. 17. Scope, Assumptions and Technical Points Page 17
  18. 18. ScopeThis product is an exposition of the technical data contained in numerousIAEA reports informed by the discussions of experts in the field of nuclearproliferation. It is a work-in-progress in that it will be revised continuouslybased on new information from the IAEA and other sources and on feedbackfrom readers.We welcome your informed commentary on the technical considerationspresented in this document. Please send your comments, with references tosource-data or documentation, to INP@AEI.ORG.This product does NOT contain policy recommendations. It is intended solelyto inform the policy community and the American public about the natureand progress of the Iranian nuclear program.This product does NOT assess Iran’s intentions to weaponize or to pursuebreakout scenarios. It is focused entirely on technical feasibility. Page 18
  19. 19. Breakout ScenariosWorst-case The worst-case scenarios assume that Iran devotes all operational centrifuges at Natanz (as of NOV 2012) to producing first additional 19.75% LEU and then 90% highly-enriched uranium (HEU), ceasing production of 3.5% LEU. Such actions would be visible to inspectors and so would most likely occur between inspections. Iranian nuclear policy and strategy does not appear to be going down this road. The scenarios assume 9,156 centrifuges spinning (the number being fed uranium as of NOV 2012) operating with an efficiency of 0.9 separative work units (SWU)/centrifuge/year (roughly the efficiency they have demonstrated). 15 kg requirement: Iran begins to race to breakout by producing 116 kg total of 19.75% LEU and then enriching that material to 90% HEU. 25 kg requirement: Iran begins to race to breakout by producing 193 kg total of 19.75% LEU and then enriching that material to 90% HEU. If Iran breaks out using a three-step process, it would need to produce 240 kg total of 19.75% LEU in total, then enrich to 60% HEU and then to 90% HEU to yield 15 kg. Assuming Iran needs 25 kg 90% HEU, it would need to produce 399 kg total of 19.75% LEU before it could convert to 60% and then 90%. These calculations assume tails assays of 2.0% and 9.3% for the two steps in the first process and 2.0%, 12.0%, and 41.1% for the three steps in the second process (see page 22). These data are derived from the Natanz facility; the Fordow installations are notably more efficient with lower tails assays.Most Likely The 9,156 centrifuges being fed in the main cascade hall at Natanz continue to produce 3.5% LEU and are not diverted to higher-level enrichment. Iran uses 85 kg 19.75% LEU to produce 15 kg 90% HEU or continues enriching to 19.75% until it has amassed approximately 141 kg 19.75% LEU, which can yield 25 kg 90% HEU. Enrichment to 19.75% occurs in 4 cascades totaling 696 IR-1 centrifuges at Fordow (2 sets of 2 interconnected cascades) and 2 cascades totaling 328 IR-1 centrifuges at the Natanz PFEP (all currently operational). Enrichment from 19.75% to 90% occurs in 6 cascades at Fordow in one step using a tails assay of 4.6%. The difference in the tails between the worst-case and most likely breakout scenarios reflects the fact that the cascades at Fordow, like the ones at Natanz PFEP, are interconnected in pairs. Page 19 Copyright © 2012 by the AEI Critical Threats Project
  20. 20. Atomic Weapons DataSmall atomic weapons can be built from cores consisting of 10-25 kg of uranium enriched to 90% U-235 (weapons-grade HEU). We use 15 kg and 25 kg to assess breakout timelines.The explosive yield of a 15 kg core is on the close order of 15 kilotons.Uranium can be enriched to HEU in a two-step or a three-step process.Both processes begin by enriching natural uranium (0.7% U-235) to 3.5% LEU.The two-step process enriches from 3.5% LEU to 19.75% LEU, and then from 19.75% LEU directly to90% HEU.The three-step process proceeds from 3.5% LEU to 19.75% LEU, from 19.75% LEU to 60% HEU, andthen from 60% HEU to 90% HEU.The most important difference between these processes is the amount of LEU required initially—thetime required to enrich from 19.75% to 90% is virtually the same for either process.The two-step process for producing 15 kg weapons-grade HEU requires 85 kg of 19.75% LEU usinginterconnected cascades (such as at Fordow) or 116 kg using non-interconnected cascades (such asthose at Natanz). Producing 25 kg weapons-grade HEU in a two-step process requires 141 kg of19.75% LEU using interconnected cascades or 193 kg using non-interconnected cascades. The three-step process requires significantly more in non-interconnected cascades (such as at Natanz).There is disagreement among experts about Iran’s ability to execute a two-step process with itscurrent technology and cascade configuration.If Iran were forced to use a three-step process, the primary delay would result from the timerequired to produce the additional 19.75% LEU, a factor that Iran could affect either by bringing morecentrifuge cascades online or by beginning to enrich with more efficient centrifuges, some of whichare already installed but not yet producing enriched uranium. Page 20 Copyright © 2012 by the AEI Critical Threats Project
  21. 21. Comparison of Estimated Breakout Times 1/16/2013 11/30/2012 3/8/2013 12/18/2012 12/25/2012 15 kg 90% HEU 11/20/2012 2-step at Natanz (15 kg) 2/1/2013 25 kg 90% HEU 2-step at Natanz (25 kg) 3-step at Natanz (15 kg) At Fordow Start + pilot Natanz 3-step at Natanz (25 kg) at Fordow +pilot NatanzAEI Critical Threats Project 2/21/2013 RED boxes denote scenarios using all 11/20/2012 1/4/2013 3-step at Natanz FEP, or majority of available cascades Start 2-step at Natanz FEP and Fordow, and PFEP (20 kg) BLUE boxes denote scenarios not clandestine facility (20 kg) using cascades in the main halls at NatanzNonproliferation PolicyEducation Center Note that some analyst estimates are 11/20/2012 based on earlier IAEA reports and do Start 12/20/2012 3/5/2013 not take account of the new 2-step at Natanz (20 kg) 3-step at Natanz (20 kg) information. Assumptions, including efficiency rates and fissile material quantities, vary across the estimates.Bipartisan Policy Center 11/20/2012 Start 1/19/2013 3/20/2013 25 kg 90% HEU 25 kg 90% HEUInstitute for Science and International Security 11/20/2012 1/7/2013 2/27/2013 Start Natanz 9,156 centrifuges At Fordow with 1392 centrifuges 16 kg 90% HEU 16 kg 90% HEUWisconsin Project onNuclear Arms Control Page 21 Copyright © 2012 by the AEI Critical Threats Project
  22. 22. Projections for the February 2013 IAEA Report IR-1 centrifuges being fed at Natanz FEP: 9,156 (moderate confidence) Total 3.5% LEU produced at Natanz FEP: 5,567 kg (moderate confidence)* IR-1 centrifuges being fed for 19.75% enrichment at Natanz and Fordow: 1,024 (low confidence) Total 19.75% LEU produced at Natanz PFEP and Fordow FEP: 184.8 kg (moderate confidence)* PREVIOUS PROJECTIONS 3.5% LEU We previously estimated that Iran would produce an additional 498 kg of 3.5% enriched uranium at Natanz during the last reporting period. The IAEA reported that Iran produced about 492 kg 3.5% enriched uranium during the period. 19.75% LEU We previously estimated that Iran would produce an additional 23 kg of 19.75% enriched uranium at Natanz and Fordow during the last reporting period. The IAEA reported that Iran produced about 29 kg 19.75% enriched uranium. The error is attributed to timing (our estimate was based on a November 4 measurement and the actual measurement took place on November 10-11) and increased production rate per centrifuge at Fordow.*Assuming IAEA measurement on 11 FEB 2013 Page 22
  23. 23. SourcesInternational Atomic Energy Agency (IAEA) – The IAEA publishes quarterly reports on Iran’s nuclear program and enrichment progress. Enriched uranium stockpile,centrifuge count, potential inspection windows, and other technical data provided by the IAEA are used in our analysis to determine historical rates of productionand to serve as a basis for building projections. IAEA reports on Iran are available at Information Service Project on Energy (WISE) – WISE provides a uranium enrichment calculator for calculating the separative work required to achieve specificlevels of U-235 concentration. The calculator uses manual inputs of feed, product, and tails figures to calculate separative work units (SWU). The resultant SWUserves as the basis for calculating time requirements. This assessment uses the WISE calculator to determine the SWU required for enriching at various levels. Theonline calculator is accessible at Jones, Nonproliferation Education Policy Center (NPEC) – Gregory Jones provided the estimated tails percentage figures for enriching to weapons-gradeuranium levels for two-step and three-step batch recycling methods (starting with 3.5% LEU) at the Natanz FEP and two-step batch recycling (from 3.5%) at NatanzPFEP/Fordow FEP, where cascades are interconnected. Jones has written that the technical assumption underlying an Iranian attempt to break out using two-stepbatch recycling without reconfiguration (from 3.5%) may not be feasible. The alternative Iranian breakout approach he suggests, adding an intermediary stepbetween 19.75% and 90% enrichment, is one that we have relied on in our analysis. Jones’s analyses are available at has written that the process for Iran to convert the U3O8 enriched up to 20% created for fuel plates back to 20% enriched UF6 gas for use in a breakout“involves dissolution by nitric acid, followed by purification by solvent extraction. These are standard processes in the nuclear industry and Iran uses them as part ofits uranium ore processing...The time required from the removal of the fresh TRR fuel from safeguards to the time to produce 19.75% enriched uranium hexafluoridewould be only ‘days to weeks.’ [citing Albert Wohlstetter et al, Swords from Plowshares, Chicago University Press, 1979]” The report is available at on this topic, Henry Sokolski, NPEC, has written that Iran could withdraw 19.75% enriched uranium from fuel plates in the form of UF6 gas in 1-2 weeks. See for Science and International Security (ISIS) – ISIS has contributed to a technical debate among experts regarding the feasibility of two-step and three-stepbatch recycling methods. ISIS analyses are available at Glaser, “Characteristics of the Gas Centrifuge for Uranium Enrichment and Their Relevance for Nuclear Weapon Proliferation,” Science and Global Security(16:1-25, 2008) – Glaser’s analysis of the P-1 centrifuge—the foundation of Iran’s IR-1 centrifuge program—is the basis for two-step batch recycling projections forenriching to weapons-grade uranium. A key aspect of Glaser’s analysis in this paper was that 90% HEU can be produced in one step from 19.7% LEU without theneed to reconfigure the arrangement of cascades. In October 2011, according to Gregory Jones, Glaser said he had “been made aware of certain phenomena thatare not taken into account” in his 2008 analysis and that “We now find that the most credible scenarios involve some kind of cascade reconfiguration.” See GregJones, “Earliest Date Possible for Iran’s First Bomb,” Nonproliferation Education Policy Center, December 6, 2011, Glaser’s original analysis, see Commission on Nuclear Non-Proliferation and Disarmament (ICCND) – The ICCND notes that a basic implosion-type nuclear weapon design with anexplosive yield of 15 kilotons would require 15 kg of weapons-grade uranium. We use this figure as the minimum 90% HEU Iran would produce to fuel one bomb.See B. Cochran and Christopher E. Paine, “The Amount of Plutonium and Highly-Enriched Uranium Needed for Pure Fission Nuclear Weapons,” NationalResources Defense Council, April 13, 1995. – Cochran and Paine assert that the “significant quantity” measurement of 25 kg weapons-grade HEU used by the IAEAgreatly overestimates the amount of fissile material required to fuel a basic implosion-type nuclear explosive device. They estimate that a state with a low technicalcapability can produce a bomb with an explosive yield of 20 kilotons with 16 kg weapons-grade HEU. See: Page 23 Copyright © 2012 by the AEI Critical Threats Project
  24. 24. For more on Iran, visit