Authors: David Albright, Sarah Burkhard and Spencer Faragaso
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In the past two years, Iran has accelerated the deployment of advanced centrifuges, after a three-year pause due to restrictions in the Joint Comprehensive Action Plan. Iran has stated its commitment to replace IR-1 centrifuges with advanced centrifuges, which can produce more enriched uranium.
Figure H.1 shows the number of advanced centrifuges deployed from 2011 to the present, and forecasts from early to mid 2022 based on the plans announced by Iran. The three enrichment plants where advanced centrifuges are deployed are the Natanz Surface Test Fuel Enrichment Plant (PFEP), the larger Underground Fuel Enrichment Plant (FEP) and the deeply buried Fordo Fuel Enrichment Plant (FFEP). With Iran Continuing to violate the terms of the JCPOA, the total number of installed advanced centrifuges has rapidly increased. Iran’s plan and statement to the IAEA indicate that it intends to install more advanced centrifuges in the next few months to further increase its enrichment capabilities.
Figure H.1. The quarterly number of advanced centrifuges installed by Iran in its three enrichment plants is forecast to be early to mid-2022 (the last vertical bar). (The number of IR-1 centrifuges is ignored in this figure; see Chapter 1.) In April 2021, the Natanz FEP was attacked, affecting half of the IR-2m and IR-1 cascades. The total number of cascades installed remains the same, but many centrifuges may have been destroyed. Since the attack, Iran is likely to replace the centrifuges damaged in these cascades, although the IAEA has not reported how many centrifuges have been replaced.
Figure H.1 shows that until 2013, the number of advanced centrifuges steadily increased, then stabilized, and then fell sharply in 2016. At that time, the focus of JCPOA's implementation was to restrict the development of advanced centrifuges, at least temporarily. Start in Iran After violating the JCPOA, this number began to increase again in the fall of 2019, but at a faster rate than before the JCPOA, reaching an unprecedented level of deployment in May 2021. In recent months, the number of advanced centrifuges deployed has increased beyond the number previously deployed by JCPOA. As of September 2021, Iran had installed approximately 1,889 advanced centrifuges in its three enrichment plants, almost all of which violated the JCPOA. By mid-November 2021, this number has increased to 2,101. In the next few months, according to Iran’s announcement to the IAEA and the Iran’s nuclear law passed in December 2020, the Atomic Energy Organization of Iran (AEOI) is expected to install as many as 1,280 advanced centrifuges, making the expected installation of advanced centrifuges. The total number of centrifuges reached 3381.
Due to the difficulty in manufacturing centrifuges, mainly caused by two destruction incidents in its centrifuge production plants in 2020 and 2021, Iran may not be able to achieve the expected number in the middle of 2022. However, Iran appears to be recovering from these attacks and is increasing the productivity of centrifuges. Therefore, the country may be able to deploy the expected number, although further delays are not surprising.
The most important advanced centrifuges today are the IR-2m, IR-4 and IR-6 centrifuges. Compared to the combination of IR-4 and IR-6 centrifuges, the recent deployment represents a retrofit of the IR-2m centrifuge.
One way to understand the importance of these three centrifuges is to consider that they can replace the IR-1 centrifuges while using the existing cascading piping and feeding and reclaiming systems at the Natanz and Forow sites. In terms of large-scale deployment, IR-4 and IR-6 centrifuges seem to be more important than IR-2m centrifuges. Iran may have encountered obstacles in sourcing required and strictly controlled materials for IR-2m centrifuges from overseas, limiting its capacity for mass production. In contrast, Iran has more successfully evaded national and international controls and sanctions regarding materials required for IR-4 and IR-6 centrifuges.
It is worth noting that when Iran began to produce 60% highly enriched uranium in April 2021, IR-4 and IR-6 centrifuges were chosen for this task instead of using the centrifuges that Iran has more operating experience. Machine, such as IR-1 or IR-2m centrifuge. The IR-1 centrifuge has been used to produce 20% enriched uranium, while the IR-2m centrifuge has been in continuous operation for several years.
In terms of understanding the impact of these three centrifuges, a key value is their estimated average enrichment output when they are arranged in a cascade of about 160-170 centrifuges, called the production cascade, which is the main force of Iran's enrichment. The average output of these estimates is lower than the theoretical value or the measured value of a single centrifuge because of inefficiencies during large-scale cascade operations. The concentration output of the IR-2m centrifuge in the production-scale cascade operation is estimated to be 3.67 SWU per year; the estimated value of the IR-4 centrifuge in the production-scale cascade is 3.3 SWU per year. The equivalent value of the IR-6 centrifuge is difficult to discern from the available information, but an estimated value of approximately 5.25 SWU per year seems reasonable. In fact, due to centrifuge damage or during the production of highly enriched uranium (such as the production of 60% enriched uranium or weapon-grade uranium), the average value may be lower. Nevertheless, the actual concentration output of these three centrifuges is much higher than that of the IR-1 centrifuge, achieving an annual production scale cascade value of 0.5-1.0 SWU.
Figure H.2 is the deployment schedule of the main advanced centrifuge types; the horizontal axis shows the year when each type was first deployed at the Natanz pilot plant, starting with the IR-2 and IR-3 centrifuges in 2008. For comparison, the vertical axis lists the theoretical concentration output of each centrifuge. It should be noted that when the data exists, the output in practice has been shown to be significantly lower than the predictions of these theoretical values. Certain centrifuge types are not included in Figure H.2; these centrifuges are included in Chapter 1.
Beginning in November 2019, Iran indicated that in addition to the existing seven types of centrifuges allowed to be deployed under the JCPOA, it has also installed seven types of centrifuges, thereby accelerating the development of centrifuges. These seven additional types are not included in Iran's confidential JCPOA enrichment plan, which is expected to deploy centrifuges until around 2030. Iran has rapidly deployed many advanced centrifuges in 2019, including many new models, which indicates that centrifuge development work continues during this period, at least after the United States ended its participation in the JCPOA in May 2018, the JCPOA has taken effect and secretly accelerated.
Among the 15 advanced centrifuge types in Figure H.2, according to the November 2021 IAEA quarterly report, IR-2m, IR-4, IR-5, IR-6, IR-6s and IR-s centrifuges Enriched uranium is being accumulated. IR-7, IR-8, IR-8B, and IR-9 centrifuges are using natural uranium raw materials for testing, but do not accumulate enriched uranium. IR-2, IR-3, IR-6m, IR-6sm and IR-8s centrifuges are not listed in the enrichment plant. The IR-2 and IR-3 centrifuges may have been retired. Another new type of centrifuge, IR9-1B, has been discussed in Chapter 1, but has not been deployed in PFEP so far, nor is it included in Figure H.2.
Figure H.2. Starting with IR-2 and IR-3 in 2008, Iran’s timetable for the deployment of major advanced centrifuge types at the Natanz pilot fuel enrichment plant is related to its theoretical enrichment output. The actual value obtained by Iran in the centrifugal enrichment of uranium alone or in cascade.
JCPOA temporarily reduced the number of IR-2m and IR-4 centrifuges installed, but despite restrictions, it only reduced the number of IR-6 centrifuges in a relatively short period of time, and did not slow down Iran’s rapid production and Production capacity. Once Iran decides to stop complying with JCPOA restrictions, it will deploy advanced centrifuges. Iran not only demonstrated its nuclear rebound capability, but also demonstrated its ability to quickly build a nuclear.
When reviewing Iran’s work on advanced centrifuges, the steps from single-machine testing to small-scale cascade testing seem to be crucial. However, according to JCPOA, this step has been allowed since the first year that JCPOA implemented IR-6 and IR-8 centrifuges, but it has not been fully implemented for IR-6 centrifuges.
Iran has gained valuable technical knowledge, experience and progress in the design and manufacture of its advanced centrifuges, which has further promoted the rapid recovery or establishment of centrifuge capabilities. These achievements cannot be reversed or erased, which has brought further challenges to the international community and IAEA seeking to rebuild the JCPOA. A thought-provoking finding is that the only way to really limit the development of a centrifuge is to stop it completely, or at least suspend it.
Figure H.3 provides the historical total enrichment capacity of Iran in Natanz and Faldo. The IR-1 capacity is blue and the advanced centrifuge capacity is red. So far, Iran’s current enrichment capacity has not exceeded the total capacity before the implementation of JCPOA, but the nature of this capacity is mainly shifting to advanced centrifuges.
Since their concentration output is much larger, although the number of installed advanced centrifuges is much smaller, starting from May 2021, it has exceeded the concentration capacity of the thousands of IR-1 centrifuges installed. As of November 2021, the number of advanced centrifuges is approximately 2,100, accounting for approximately 34% of the number of IR-1 centrifuges deployed by Natanz and Fuldo, and their output is higher than the deployed 6,290 IR-1 centrifuges Concentration output is about 48% higher. If Iran reaches the expected number of 3381 advanced centrifuges, their enrichment capacity will be nearly two and a half times that of IR-1 centrifuges currently deployed. This advanced centrifuge capacity will also be comparable to all of Iran's estimated 16,000 IR-1 centrifuges (deployed and stored), while the number of centrifuges will only account for 21% of the total number of centrifuges. This comparison ignores any stored advanced centrifuges.
Figure H.3. IR-1 and advanced centrifuges are based on a quarter of the total concentration capacity, and there is a projection on the far right of the chart.
In the development of advanced centrifuges, Iran lengthened the centrifuge rotor assembly, slightly increased the wall speed by increasing the diameter, and changed the rotor tube material to carbon fiber. Compared with the high-strength aluminum used in Iranian IR-1 centrifuges, carbon fiber allows for higher rotor speeds. Iran can also achieve higher speeds by choosing high-strength maraging steel rotor components like Pakistan, but Iran seems to have encountered difficulties in sourcing this material. However, excluding the IR-1 centrifuge, Iran’s enrichment production seems to increase with length, indicating that it is difficult for Iran to run its centrifuges at the higher speeds provided by the carbon fiber rotors.
The difficulties of high-strength maraging steel also seem to have prompted Iran to develop carbon fiber bellows, an important part of Iran's longer centrifuges, although carbon fiber bellows are more difficult to manufacture than bellows made of maraging steel. Unsurprisingly, Iran seems to have been having difficulties in manufacturing carbon fiber bellows, continuing to deploy shorter centrifuge models that do not require bellows, while developing longer centrifuges. It also focuses on deploying advanced centrifuges with only one carbon fiber bellows, a centrifuge design that is easier to develop than a centrifuge design with two or more bellows.
IR-s centrifuges are worthy of attention. It is an abnormal value in a shorter centrifuge, with a relatively high theoretical concentration output, which means that the wall speed is more in line with the potential of a carbon fiber rotor. Generally, Iran’s advanced centrifuges reach speeds lower than the optimal speed of carbon fiber rotors. However, IR-s may be being tested at these higher speeds, such as the order of 700 meters per second. Achieving these higher speeds is difficult, but can significantly increase the concentration output.
The recent attack on the Iranian Centrifuge Assembly Center (ICAC) and centrifuge manufacturing plant in Natanz near Karaj may have restricted or slowed Iran’s ability to install advanced centrifuges. The figures installed in three centrifuge factories last year support this hypothesis.
The Independent Commission Against Corruption was built to be able to produce several to several thousand advanced centrifuges each year. Iran’s subsequent manufacturing and assembly capacity appears to have been greatly reduced, down to the level of hundreds of advanced centrifuges per year. However, Iran has been rebuilding its centrifuge manufacturing capacity, so without more attacks or negotiated restrictions, an increase should be expected.
Nevertheless, due to the unclear Iran’s policy on production and deployment quantities, and the low transparency of Iran’s centrifuge manufacturing base since February 2021, including the refusal to allow the reinstallation of IAEA monitors in the plant, it is difficult to predict Advanced centrifuge productivity. Karaji facility after the attack. In addition, the destruction of Natanz and Karaj has restricted the production of centrifuges to an unknown extent. Although the November 2021 IAEA report did not contain information on the operating status of the Karaj site, the Wall Street Journal reported that the site resumed limited-scale centrifuge production in August 2021, and subsequently accelerated production. "At least 170 parts for advanced centrifuges"" until mid-November 1
In addition, it is not clear where Iran will assemble its advanced centrifuge after the ICAC destroys it. However, the large-scale and sudden deployment of various types of advanced centrifuges has raised questions about how, where, and when these centrifuges are produced. 2 In the MEMRI TV interview in April 2021, Ali-Akbar Salehi, the head of AEOI, stated that the temporary replacement has been completed. In the English subtitles, he was quoted saying: "It was announced today that we managed to build a hall instead of the missing one. This is of course temporary." 3 The subtitles did not specify the location, although it is said that it is at the Natanz site. The Natanz plant offers several possible locations for temporary assembly of advanced centrifuges.
In the long term, Iran plans to assemble centrifuges in a deep underground replacement facility near Natanz, although the progress of its construction is unclear. It is expected that the site will be large enough to produce centrifuges of the same scale as the ICAC plan, that is, thousands of advanced centrifuges each year.
In general, AEOI has tried to develop many types of centrifuges, which are too many for commercial or economic plans. Some developments, such as the proudly claimed ultra-long centrifuge, seem to be aimed at impressing domestic audiences, rather than deploying them on a large scale within a reasonable time frame. The strategic nature of the Iranian centrifuge program cannot be ignored.
These more powerful advanced centrifuges make it easier for Iran to build a secret enrichment plant, which will be smaller and only house a small part of the centrifuges Iran needed when it tried to complete and install IR-1 centrifuges in 2009. Qom’s secret enrichment plant is designed to produce highly enriched uranium.
Since only a relatively small number of advanced centrifuges are needed to build a secret and powerful concentration plant, people are increasingly concerned about the falling production of the main components of advanced centrifuges or the entire rotor assembly. As of November 2021, the inventory is close to 20% and 60% of enriched uranium, and about 650 IR-6 centrifuges are enough to break through secret enrichment sites and produce enough weapon-grade uranium for nuclear explosions in about a month.
Undoubtedly, because there are no agreed restrictions or stronger IAEA inspections than today, concerns about the construction of another secret enrichment plant in Iran will grow over time. After all, the Natanz Enrichment Plant and the Fordo Enrichment Plant were started secretly. The latter was part of a secret military plan to produce weapons-grade uranium. The facility was not discovered in six or seven years. 4 Using advanced centrifuges, secret factories can be smaller, stronger, and harder to discover. This possibility should not be underestimated.
Unless compensatory measures are taken, such as destroying rather than storing advanced centrifuges, the new JCPOA will not maintain the 12-month breakthrough timetable to produce enough weapon-grade uranium to make nuclear weapons. If Iran seals up its advanced centrifuges, the time may only be five to six months.
As Iran has accumulated a large number of undeclared assembled centrifuges and the risk of sensitive centrifuge components, if some compensation actions are not taken, for example, the International Atomic Energy Agency will verify the main components of the advanced centrifuge declared by Iran to ensure that its safety is complete and correct. . So far, Iran has shown no interest in providing such cooperation. Nonetheless, the IAEA is expected to try to verify Iran’s statement, which will complicate the implementation of the agreement, but will ultimately provide more assurance for any breakthrough estimates.
The Institute’s breakthrough calculations also ignore Iran’s ability to quickly build and deploy additional advanced centrifuges, and its practice of skipping the production of weapon-grade uranium in the Khan’s four-step process, both of which allow faster Breaking through to the first nuclear weapon, in the following months, its centrifuge capabilities improved faster, allowing faster production of WGU sufficient for the second, third, and fourth nuclear weapons.
Seeking to suspend the research and development of centrifuges and the construction and operation of centrifuge manufacturing bases will help alleviate the challenges to the integrity and feasibility of JCPOA.
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1. Laurence Norman, "Diplomats claim that Iran resumes production of advanced nuclear program components", The Wall Street Journal, November 16, 2021, https://www.wsj.com/articles/iran-resumes-production-of -The diplomat of the senior nuclear program said 11637079334. ↩
2. There is no concrete evidence that Iran has resumed the production of IR-1 centrifuges, but the recent AEOI statement regarding the deployment of six-stage more powerful IR-1 centrifuges in FEP raises at least one question, namely whether the production of IR-1 components has resumed . ↩
3. MEMRI, "Iranian Nuclear Supervisor Day before the Natanz Nuclear Facility: We Launched the IR-6 Centrifuge Chain", MEMRI TV video, interview with Ali-Akbar Salehi, on Channel 1, April 10, 2021 (Iran) Broadcast, https://www.youtube.com/watch?v=qLmQJOhSusE. Note: In some cases, Iranian media misinterpreted Cascade, calling it "chain" in English. The translation of the college confirmed the accuracy of the subtitles. In the description accompanying the video clip also attributed to MEMRI TV, it appears that there has been a mistranslation. According to this description, Salehi said that a hall of the Independent Commission Against Corruption has been restored and the centrifuges have been reassembled there. In fact, he did not make such a statement in the video. In addition, the commercial satellite image of the Independent Commission Against Corruption in November 2021 showed that it was almost destroyed and there is no sign of recovery. ↩
4. David Albright and Sarah Burkhard and the excellent ISIS team, Iran’s dangerous nuclear weapons pursuit, (Washington, DC: Institute of Science and International Security, 2021). ↩
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