Thread by @TheGoodISIS

A long thread covering the highlights of our new Comprehensive Survey of Iran's Advanced Centrifuges:

In the last 2 yrs, Iran has accelerated its deployment of advanced centrifuges, following a lull of 3 yrs created by the JCPOA. Iran has demonstrated its commitment to replace the IR-1 centrifuge with advanced centrifuges, which can produce considerably more enriched uranium. 1/

This graph shows the number of advanced centrifuges deployed from 2011 to today, w/ a projection for early to mid-2022 based on Iran’s announced plans. The total number of installed advanced centrifuges has been increasing rapidly as Iran continues to violate the JCPOA. 2/

As of September 2021, Iran had approximately 1889 advanced centrifuges installed at its three enrichment plants, almost all in violation of the JCPOA. By mid-November 2021, this number increased to 2101. 3/

During the next several months, based on Iran’s announcements to the IAEA and a December 2020 Iranian nuclear law, the AEOI is projected to install up to another 1280 advanced centrifuges, bringing the projected total to 3381 installed advanced centrifuges. 4/

Due to difficulties in manufacturing centrifuges, caused mainly by two sabotage events in 2020 and 2021 at its centrifuge production plants, Iran may have trouble achieving the projected number by mid-2022. 5/

However, Iran appears to be recovering from these attacks and is stepping up its centrifuge production rates. As a result, the country may be able to deploy the projected number, although further delays would be unsurprising.6/

The most important advanced centrifuges today are the IR-2m, IR-4, and IR-6 centrifuges. The recent deployments represent a build-back for the IR-2m centrifuge, in contrast to a build-up for the IR-4 and the IR-6 centrifuges. 7/

One way to see the importance of these three centrifuges is to consider that they can replace the IR-1 centrifuges while utilizing the existing cascade piping and feed and withdrawal systems at the Natanz and Fordow sites. 8/

In terms of wide-scale deployments, IR-4 & IR-6 centrifuges appear more important than the IR-2m centrifuge. Iran may have encountered obstacles procuring tightly controlled materials from overseas for the IR-2m centrifuge, limiting its ability to produce it in larger numbers. 9/

In contrast, Iran has been more successful evading national and international controls and sanctions with regards to materials needed for the IR-4 and IR-6 centrifuges.10/

Notably, when Iran started production of 60 percent highly enriched uranium in April 2021, the IR-4 and IR-6 centrifuges were chosen for this task, rather than using one with which Iran had more operational experience, such as the IR-1 or IR-2m centrifuge. 11/

In terms of understanding the impact of these three centrifuges, a key value is their estimated average enrichment output when arranged into cascades of about 160-170 centrifuges, called production-scale cascades, the workhorse for enrichment in Iran. 12/

These estimated average outputs are less than theoretical values or single centrifuge measured values because of inefficiencies experienced during larger-scale cascade operation. 13/

The enrichment output of the IR-2m centrifuge when operating in a production-scale cascade is estimated at 3.67 SWU per year; the estimated value for the IR-4 centrifuge in a production-scale cascade is 3.3 SWU per year. 14/

The equivalent value for the IR-6 centrifuge is harder to discern from the available information, but an estimated value of approximately 5.25 SWU per year appears justified and reasonable. 15/

In practice, lower average values may result, due to centrifuge breakage or during the production of highly enriched uranium, such as production of 60 percent enriched uranium or weapon-grade uranium. 16/

Nonetheless, the practical enrichment output of these three centrifuges is far higher than that of the IR-1 centrifuge, which achieves production-scale cascade values of 0.5-1.0 SWU per year. 17/

A timeline of the deployment of advanced centrifuge types; the x-axis giving the year in which each type was first deployed at the pilot plant at Natanz, starting with the IR-2 & IR-3 centrifuges in 2008. The y-axis lists each centrifuge’s theoretical enrichment output.18/

It should be noted that, when data exist, the output in practice has proven to be significantly less than predicted by these theoretical values. 19/

Starting in November 2019, Iran demonstrated that it had accelerated its centrifuge research and development by installing seven types of centrifuges in addition to the existing seven types allowed to be deployed under the JCPOA. 20/

These seven additional types were not included in Iran’s confidential JCPOA enrichment plan, which projected the deployment of centrifuges up to about 2030. 21/

Iran’s rapid deployment of many advanced centrifuges in 2019, including many new models, suggests that centrifuge development work continued when the JCPOA was in force & accelerated secretly at least as soon as the United States ended its participation in May 2018. 22/

Of the 15 centrifuge types in the timeline, as of the November 2021 quarterly IAEA report, the IR-2m, IR-4, IR-5, IR-6, IR-6s, and IR-s centrifuges were accumulating enriched uranium. 23/

The IR-7, IR-8, IR-8B, and IR-9 centrifuges were being tested with natural uranium feed but not accumulating enriched uranium. The IR-2, IR-3, IR-6m, IR-6sm, and IR-8s centrifuges were not listed as present in an enrichment plant. 24/

The IR-2 and IR-3 centrifuges may have been retired. An additional new centrifuge type, the IR9-1B, has not been deployed at the PFEP to this date and is not included in the timeline. 25/

The JCPOA reduced the number of installed IR-2m and IR-4 centrifuges temporarily, but despite limitations, it only reduced the number of IR-6 centrifuges for a relatively short period of time. 26/

It did not slow Iran’s ability to rapidly produce and deploy advanced centrifuges once Iran decided to stop abiding by the JCPOA limits. Iran has demonstrated its ability not only for a nuclear snap-back but also for a snap nuclear build-up. 27/

Iran has gained valuable technical knowhow, experience, and advancements in the designing and building of its advanced centrifuges, further enabling a rapid build-back or build-up of centrifuge capabilities. These gains cannot be reversed or erased. 28/

Iran’s total historical theoretical enrichment capacity at Natanz and Fordow, where the IR-1 capacity is in blue and advanced centrifuge capacity is in red. 29/

So far, Iran’s current enrichment capacity has not exceeded its total capacity prior to the JCPOA’s implementation but the nature of that capacity is shifting predominately to advanced centrifuges. 30/

Because of their far greater enrichment outputs, the installed advanced centrifuges, although many fewer in number, began in May 2021 to exceed the enrichment capacity of the several thousands of installed IR-1 centrifuges. 31/

As of November 2021, the advanced centrifuges numbered about 2100, or about 34 percent of the number of deployed IR-1 centrifuges at Natanz and Fordow, and they out-produced the 6290 deployed IR-1 centrifuges in enrichment output by about 48 percent. 32/

If Iran reaches the projected number of 3381 advanced centrifuges, they will have almost two and half times the enrichment capacity of the currently deployed IR-1 centrifuges. 33/

This advanced centrifuge capacity will also rival all of Iran’s estimated 16,000 IR-1 centrifuges—deployed and stored—with only 21 percent of the number of centrifuges. (This comparison ignores any stored advanced centrifuges.) 34/

In its development of advanced centrifuges, Iran has lengthened their centrifuge rotor assemblies, boosted their wall speed marginally by increasing the diameter, and changed the rotor tube material to carbon fiber. 35/

However, excluding the IR-1 centrifuge, Iran’s enrichment output appears to have increased mostly with length, indicating Iran has had difficulties operating its centrifuges at the higher speeds offered by carbon fiber rotors. 36/

Difficulties with high strength maraging steel appear to have also motivated Iran to develop the bellows, an important component of Iran’s longer centrifuges, from carbon fiber, although carbon fiber bellows are much more difficult to make than ones made from maraging steel.37/

Not unexpectedly, Iran appears to have ongoing difficulties making carbon fiber bellows, continuing to deploy shorter centrifuge models that do not need a bellows in parallel to developing the longer centrifuges. 38/

It is also concentrating on deploying advanced centrifuges with only one carbon fiber bellows, a centrifuge design easier to develop than one with two or more bellows.40/

The IR-s centrifuge bears watching. It is an outlier among the shorter centrifuges, with a relatively high theoretical enrichment output, implying a wall speed more consistent with the potential of carbon fiber rotors. 41/

Achieving these higher speeds is difficult but would allow significant increases in enrichment output. 42/

Recent attacks on the Natanz Iran Centrifuge Assembly Center (ICAC) and a centrifuge manufacturing plant at a site called TABA (also known as TESA), situated near Karaj, have likely limited or slowed Iran’s ability to install advanced centrifuges. 43/

The ICAC was built to have a capacity to make a few to several thousand advanced centrifuges per year. Iran’s subsequent manufacturing and assembly capacity appears to have been substantially reduced, down to a level of several hundred advanced centrifuges per year. 44/

However, Iran has been rebuilding its centrifuge manufacturing capacity, so increases should be expected, absent more attacks or negotiated limits. 45/

Nonetheless, advanced centrifuge production rates are hard to predict, because of unclear Iranian policies on the number produced versus deployed, and less Iranian transparency at its centrifuge manufacturing sites since February 2021.. 46/

.. including the refusal to allow the re-installation of IAEA monitors at the Karaj facility after the attack. In addition, the sabotage events at Natanz and Karaj have limited the production of centrifuges to an unknown extent.47/

While the IAEA report contains no information on the operational status of Karaj, @laurnorman @WSJ reported that the site resumed centrifuge production on a limited scale in August & accelerated production, producing “at least 170 advanced centrifuges” by mid-November. 48/

Further, it is unclear where Iran has been assembling its advanced centrifuges with the ICAC’s destruction. The large, and sudden deployment of various types of advanced centrifuges, however, raises questions as to how, where, and when those centrifuges were produced. 49/

In an April 2021 MEMRI TV interview, then AEOI-head Ali-Akbar Salehi indicated that a temporary replacement was built. 50/

In the longer term, Iran plans to assemble centrifuges in a deeply buried underground replacement facility near Natanz, although its construction progress is unclear. 51/

Since only a relatively small number of advanced centrifuges would be needed to set up a secret and powerful enrichment plant, concern increases about unaccounted production of major parts for advanced centrifuges or whole rotor assemblies. 52/

With stocks of near 20 percent and 60 percent enriched uranium as of November 2021, about 650 IR-6 centrifuges would be enough to breakout at a clandestine enrichment site and produce enough weapon-grade uranium for a nuclear explosive in about one month.53/

Unless compensatory steps are taken, such as destroying advanced centrifuges, a renewed JCPOA will not maintain a 12-month timeline to produce enough weapon-grade uranium for a nuclear weapon. If Iran mothballs its advanced centrifuges, timelines of only 5-6 months are likely.54/

Because of the risk that Iran has accumulated a stock of undeclared assembled centrifuges & components, breakout timelines could be further reduced, absent some compensatory action, such as IAEA verification of Iran’s declaration of major components of advanced centrifuges. 55/

So far, Iran has shown no interest in providing such cooperation. 56/

Institute breakout calculations also ignore Iran’s demonstrated capability to rapidly build and deploy additional advanced centrifuges, as well as its practice of skipping steps in the Khan four-step method of producing weapon-grade uranium. 57/

Overall, seeking a moratorium on centrifuge research and development and the construction and operation of centrifuge manufacturing sites would help alleviate these challenges to the integrity and viability of the JCPOA. 58/

Read the full report, which has many tables on the technical parameters of the different centrifuge types and their historical deployment at Iran's enrichment sites here: isis-online.org/uploads/isis-r… 59/59 END