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 INP@aei.org. For more on Iran's nuclear program, visit www.irantracker.org.

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
www.criticalthreats.org
Copyright © 2012 by the AEI Critical Threats Project

2. November 2012 International Atomic Energy Agency (IAEA) Findings
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.
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. Status of Near-20% Enriched Uranium
Iran has enough near-20% enriched uranium with which to produce weapons-grade
uranium (WGU) for one warhead. Some of this material is currently stored in oxide
powder 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 its
uranium ore processing.”1 The conversion can be done using specialized facilities and can be accomplished in “days to weeks.”2 The near-20% LEU can
only be classified as unusable in a breakout once the fuel assemblies containing the U3O8 are inserted and irradiated in a reactor core. Only a small
fraction 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 3
2) Ibid.

4. Key Points
IRAN’S ENRICHMENT CAPABILITIES ARE NO LONGER
THE PRIMARY BOTTLENECK IN A NUCLEAR BREAKOUT SCENARIO
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.
Page 4
Copyright © 2012 by the AEI Critical Threats Project

5. 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.
Page 5

6. 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. Page 6

7. Iran has outfitted the hardened Fordow enrichment facility with 2,784 IR-1
centrifuges. This expansion gives Iran the capacity to produce near-20%
enriched uranium at a faster rate and the means to convert that stockpile
to 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. 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-12
Enrichment data source: IAEA Page 8
Copyright © 2012 by the AEI Critical Threats Project

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 gradually
Kilograms 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-14
BLACK: Reported production
RED: 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. 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 be
11/29/2012 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. 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. 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. 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 uranium
SWU = Separative work unit, a measure of the amount of effort
solid metal (90% U-235)
required to process nuclear material. The SWU requirement is
used to determine the time needed to enrich uranium with a given
number of centrifuges operating at a given efficiency. Page 13
Copyright © 2012 by the AEI Critical Threats Project

14. Iran’s Declared Uranium Enrichment Facilities
Fordow 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
145
amount IAEA reported has been
transferred 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
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15. Natanz Enrichment Facilities
Pilot 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
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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. Scope, Assumptions and Technical Points
Page 17

18. Scope
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 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-data or documentation, to INP@AEI.ORG.
This product does NOT contain policy recommendations. It is intended solely
to inform the policy community and the American public about the nature
and progress of the Iranian nuclear program.
This product does NOT assess Iran’s intentions to weaponize or to pursue
breakout scenarios. It is focused entirely on technical feasibility.
Page 18

19. Breakout Scenarios
Worst-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
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20. Atomic Weapons Data
Small 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 to
90% HEU.
The three-step process proceeds from 3.5% LEU to 19.75% LEU, from 19.75% LEU to 60% HEU, and
then from 60% HEU to 90% HEU.
The most important difference between these processes is the amount of LEU required initially—the
time 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 using
interconnected cascades (such as at Fordow) or 116 kg using non-interconnected cascades (such as
those at Natanz). Producing 25 kg weapons-grade HEU in a two-step process requires 141 kg of
19.75% 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 its
current technology and cascade configuration.
If Iran were forced to use a three-step process, the primary delay would result from the time
required to produce the additional 19.75% LEU, a factor that Iran could affect either by bringing more
centrifuge cascades online or by beginning to enrich with more efficient centrifuges, some of which
are already installed but not yet producing enriched uranium.
Page 20
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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 Natanz
AEI 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
Natanz
Nonproliferation Policy
Education 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% HEU
Institute 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% HEU
Wisconsin Project on
Nuclear Arms Control
Page 21
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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. Sources
International 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 production
and to serve as a basis for building projections. IAEA reports on Iran are available at http://www.iaea.org/newscenter/focus/iaeairan/iaea_reports.shtml.
World Information Service Project on Energy (WISE) – WISE provides a uranium enrichment calculator for calculating the separative work required to achieve specific
levels of U-235 concentration. The calculator uses manual inputs of feed, product, and tails figures to calculate separative work units (SWU). The resultant SWU
serves as the basis for calculating time requirements. This assessment uses the WISE calculator to determine the SWU required for enriching at various levels. The
online calculator is accessible at http://www.wise-uranium.org/nfcue.html.
Gregory Jones, Nonproliferation Education Policy Center (NPEC) – Gregory Jones provided the estimated tails percentage figures for enriching to weapons-grade
uranium 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 Natanz
PFEP/Fordow FEP, where cascades are interconnected. Jones has written that the technical assumption underlying an Iranian attempt to break out using two-step
batch recycling without reconfiguration (from 3.5%) may not be feasible. The alternative Iranian breakout approach he suggests, adding an intermediary step
between 19.75% and 90% enrichment, is one that we have relied on in our analysis. Jones’s analyses are available at http://www.npolicy.org/.
Jones 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 of
its 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 hexafluoride
would be only ‘days to weeks.’ [citing Albert Wohlstetter et al, Swords from Plowshares, Chicago University Press, 1979]” The report is available at http://
www.npolicy.org/article_file/Fueling_the_Tehran_Research_Reactor-Technical_Considerations_on_the_Risks_and_Benefits.pdf.
Further 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
http://www.nationalreview.com/corner/188387/fueling-around-iran-and-bomb/henry-sokolski.
Institute for Science and International Security (ISIS) – ISIS has contributed to a technical debate among experts regarding the feasibility of two-step and three-step
batch recycling methods. ISIS analyses are available at http://isis-online.org/.
Alexander 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 for
enriching 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 the
need to reconfigure the arrangement of cascades. In October 2011, according to Gregory Jones, Glaser said he had “been made aware of certain phenomena that
are 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 Greg
Jones, “Earliest Date Possible for Iran’s First Bomb,” Nonproliferation Education Policy Center, December 6, 2011, http://npolicy.org/article.php?aid=1124&rid=4.
For Glaser’s original analysis, see http://www.princeton.edu/sgs/publications/sgs/archive/16-1-Glaser.pdf.
International Commission on Nuclear Non-Proliferation and Disarmament (ICCND) – The ICCND notes that a basic implosion-type nuclear weapon design with an
explosive 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 http://icnnd.org/Reference/reports/ent/part-ii-4.html.
Thomas B. Cochran and Christopher E. Paine, “The Amount of Plutonium and Highly-Enriched Uranium Needed for Pure Fission Nuclear Weapons,” National
Resources Defense Council, April 13, 1995. – Cochran and Paine assert that the “significant quantity” measurement of 25 kg weapons-grade HEU used by the IAEA
greatly overestimates the amount of fissile material required to fuel a basic implosion-type nuclear explosive device. They estimate that a state with a low technical
capability can produce a bomb with an explosive yield of 20 kilotons with 16 kg weapons-grade HEU. See: http://www.nrdc.org/nuclear/fissionw/
fissionweapons.pdf. Page 23
Copyright © 2012 by the AEI Critical Threats Project

24. For more on Iran, visit
www.irantracker.org