Analysis of IAEA Iran Verification and Monitoring Report — November 2023

by David Albright, Sarah Burkhard, Spencer Faragasso, and Andrea Stricker [1]

November 20, 2023

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This report summarizes and assesses information in the International Atomic Energy Agency’s (IAEA’s) quarterly report, dated November 13, 2023, Verification and monitoring in the Islamic Republic of Iran in light of United Nations Security Council resolution 2231 (2015), including Iran’s compliance with the Joint Comprehensive Plan of Action (JCPOA). It also includes findings from a separate IAEA report, NPT Safeguards Agreement with the Islamic Republic of Iran, dated November 15, 2023, referred to alternatively as NPT Report or NPT Safeguards Report.


  • Iran’s stocks of enriched uranium and its centrifuge capacity combined are sufficient to make enough weapon-grade uranium (WGU), taken as 25 kilograms (kg) of WGU, for six nuclear weapons in one month, eight in two months, ten in three months, eleven in four months, and twelve in five months. This represents a growth in Iran’s breakout capabilities in months three through five, resulting from the continued growth of enriched uranium stocks. Centrifuge capacity has remained relatively constant.

  • With Iran’s growing experience and using only a portion of its stock of 60 percent enriched uranium, Iran could choose to produce its first quantity of 25 kg of WGU in as little as seven days, down from the Institute’s previous estimate of 12 days. The shorter timeframe results from a scenario in which Iran dedicates four advanced centrifuge cascades to the task and uses a higher tails assay, causing faster production of WGU but requiring more 60 percent feed to do so. This breakout could be difficult for the IAEA to detect promptly, if Iran delayed inspectors’ access.

  • According to the IAEA’s NPT safeguards report, after almost five years since the IAEA first detected undeclared uranium at the first site relevant to its investigation, and after many chances for Iran to provide explanations, the IAEA continues to conclude that undeclared nuclear-related activities or undeclared nuclear material were present at all four sites under investigation. The IAEA reports, “The Agency has not changed its assessment either of the undeclared nuclear-related activities at the four locations […] or of the origin of the uranium particles […] found at three of these four undeclared locations in Iran.”

  • The NPT safeguards report language makes clear that not only was there little Iranian cooperation over the last two and a half months, but also that Iran shows no real willingness to cooperate in the future. In a further demonstration of Iran’s strategy to reduce transparency over its sensitive nuclear programs, for political reasons, Iran withdrew the designation of European inspectors with experience in enrichment technology. The Wall Street Journal reports that eight inspectors had to leave Iran.2 The IAEA called this move “extreme and unjustified” and underscored that this “seriously affected the agency’s work.” Iran responded that the IAEA’s complaint “is not compelling and lacks any legal basis,” and said only that it was exploring possibilities to address the issue.

  • The net overall enriched uranium stock, including all levels of enrichment and all chemical forms, increased by 691.2 kg from 3795.5 kg to 4486.8 kg (Uranium mass or U mass).

  • Iran’s stockpile of 60 percent highly enriched uranium (HEU) was 128.3 kg (U mass) or 189.8 kg uranium hexafluoride mass (hex mass) as of October 28, 2023.

  • The average production rate of 60 percent HEU dropped from 4.3 kg (U mass) per month to 2.9 kg. At this rate, Iran can produce about 35 kg (U mass) annually.

  • However, Iran did not downblend any 60 percent HEU during this reporting period. Thus, the 60 percent HEU stock grew at a faster average rate than during the previous period. It grew by 94 grams (U mass) per day (6.7 kg over 71 days), compared to the previous 77 grams per day (7.5 kg over 97 days). Of note, Iran doubled its production of near 60 percent HEU when it started, in November 2022, to enrich to near 60 percent HEU in two advanced centrifuge cascades at Fordow. Thus, for six months, from December 2022 to June 2023, it accumulated about double the monthly average amount compared to the previous year and might still have been able to hit its annual production target even if it had stopped producing 60 percent altogether for the subsequent six months.

  • Iran continued to produce 60 percent HEU from 5 percent low enriched uranium (LEU) feed in advanced centrifuge cascades at the above-ground Pilot Fuel Enrichment Plant (PFEP) and the below-ground Fordow Fuel Enrichment Plant (FFEP); the latter includes an IR-6 centrifuge cascade that is easily modifiable to change operations. This cascade was at the center of an IAEA-detected undeclared mode of operation in January 2023. It was interconnected with another IR-6 cascade to produce HEU, and subsequently, the IAEA detected the presence of near-84 percent HEU particles at the cascade’s product sampling point.

  • In its May 2023 report on Iran’s compliance with the Nuclear Non-Proliferation Treaty (NPT), the IAEA reported that the agency installed enrichment monitoring devices (EMD) at both the FFEP and at the PFEP to “monitor the enrichment level of the HEU being produced by Iran.” These monitors are not JCPOA-related but are installed pursuant to Iran’s comprehensive safeguards agreement (CSA) with the agency. IAEA Director General Rafael Grossi confirmed in a press conference that the EMD data will notify the IAEA of “another oscillation or otherwise” in the enrichment level in “real-time.” The IAEA reported previously that, “The evaluation of the data collected confirmed the general good functioning of the systems.” However, “adjustments and changes to operational procedures required to enable their commissioning […] are being discussed with Iran.” The IAEA provides no update on the status of the EMDs in the most recent report.

  • The IAEA’s technical report is shorter in length and omits previously reported details, including how much of the 20 percent enriched uranium and 60 percent HEU stocks Iran keeps at the Esfahan Fuel Plate Fabrication Plant (FPFP), where Iran maintains a capability to make enriched uranium metal. According to previous reports, Iran was storing the majority of those stocks at Esfahan. Storage of so much proliferation-sensitive material at the FPFP, which may not be as thoroughly monitored as Natanz and Fordow, requires enhanced IAEA safeguards to detect and prevent diversion to a secret enrichment plant. For example, there should be stepped-up inspector presence and remote camera surveillance.

  • As of October 28, 2023, Iran had an IAEA-estimated stock of 567.1 kg of 20 percent enriched uranium (U mass and in the form of UF6), equivalent to 838.9 kg (hex mass), representing an increase of 31.3 kg from 535.8 kg (U mass). Iran also had a stock of 32.7 kg (U mass) of 20 percent uranium in other chemical forms. The average production rate of 20 percent enriched uranium at the FFEP remained steady at about 13.4 kg (U mass) or 19.9 kg (hex mass) per month. Iran’s deployment of advanced centrifuges has remained fairly steady since February 2023, with about one new advanced centrifuge cascade installed during each of the three subsequent reporting periods. Iran now has almost 6300 advanced centrifuges at Natanz and Fordow, where most are deployed at the Natanz Fuel Enrichment Plant (FEP) (see Figure 1).

  • Including the installed IR-1 centrifuges at the FEP and FFEP brings the total number of installed centrifuges to about 13,500. It should be noted that many of the advanced centrifuges are deployed but not enriching uranium, and the IR-1 centrifuges have a far lesser ability to enrich uranium than the advanced ones. During this reporting period, Iran installed one additional cascade of IR-4 centrifuges at the FEP, where Iran now has a total of 36 cascades of IR-1 centrifuges, 21 cascades of IR-2m centrifuges, six cascades of IR-4 centrifuges, and three cascades of IR-6 centrifuges installed. An additional six IR-4 centrifuge cascades are planned, and the installation of one IR-4 cascade was ongoing.

  • Iran did not install any additional advanced centrifuge cascades at the FFEP, where it is currently operating six IR-1 centrifuge cascades and two IR-6 centrifuge cascades, although it plans to install up to 14 additional IR-6 centrifuge cascades. This lull in deployment was preceded by a spike in advanced centrifuge deployment from August 2022 to February 2023. A slowing of advanced centrifuge deployments and enrichment using those machines may be one reported term of an informal nuclear understanding with the United States, although this is unverified. It is unclear whether this means Iran is producing fewer centrifuges than expected, implying possible manufacturing difficulties, or is keeping newly produced machines in unmonitored storage instead.

  • Iran’s current, total operating enrichment capability is estimated to be about 19,800 separative work units (SWU) per year, where only cascades enriching uranium during this reporting period are included in the estimate. As of this reporting period, Iran was not yet using its fully installed enrichment capacity at the FEP, which, if operational, would total about 31,000 SWU/yr.

  • Iran’s stockpile of near 5 percent LEU increased by 267.2 kg (U mass) to 2218.1 kg (U mass) or 3281.2 kg (hex mass). Average production of near 5 percent LEU at the FEP decreased, consistent with the reporting that Iran used natural uranium as feedstock instead of up to 2 percent LEU.

  • Despite the increase during this reporting period in the amount of uranium enriched between two and five percent, Iran has not prioritized stockpiling this material. For example, it has not made planned progress on the Enriched Uranium Powder Plant, a key civil facility to convert less than 5 percent enriched uranium hexafluoride into a uranium oxide powder for use in nuclear power reactor fuel. These two choices are at odds with Iran’s contention that its primary goal is to accumulate 4-5 percent enriched uranium for use in nuclear power reactor fuel. Instead, Iran has used this stock extensively to produce near 20 percent and 60 percent enriched uranium, far beyond Iran’s civilian needs.

  • The IAEA states in the NPT safeguards report that Iran provided new data the IAEA needs to assess to see whether the agency can resolve a discrepancy in Iran’s natural uranium inventory at the Uranium Conversion Facility (UCF). The IAEA previously reported a shortfall in Iran’s declaration, which may indicate that Iran mixed into the UCF inventory undeclared uranium it used in the past at the Lavisan-Shian site during its early-2000s nuclear weapons program. After acknowledging a discrepancy, Iran insisted that the discrepancy is “inaccurate” and “baseless,” and that “differences” are “predictable” and that “the matter is considered as resolved.” The IAEA did not agree with Iran’s claim.

  • The IAEA reports that Iran has not started commissioning the Arak reactor, now called the Khondab Heavy Water Research Reactor (KHRR), or IR-20. Iran previously informed the IAEA that it expected to commission the reactor in 2023 and start operations in 2024, but construction efforts on the reactor continue and Iran has provided no update.

  • The IAEA underscores that it has been “two years and nine months since Iran stopped provisionally applying its Additional Protocol and, therefore, since it provided updated declarations and the Agency was able to conduct complementary access to any sites and locations in Iran.”

  • The IAEA reports no new progress on installing new surveillance cameras at Iran’s nuclear-related facilities, including centrifuge manufacturing and assembly sites. The IAEA proposed installing cameras at the Natanz centrifuge workshops, but Iran refused. The IAEA also proposed conducting consistency checks on cameras installed at the Esfahan centrifuge facility, and Iran refused. Iran also has not turned over data or footage associated with monitoring devices and cameras, as it committed in an IAEA/Iran Joint Statement from March 2023.

  • The absence of monitoring and surveillance equipment, particularly since June 2022, has caused the IAEA to doubt its ability to ascertain whether Iran has diverted or may divert advanced centrifuges. A risk is that Iran could accumulate a secret stock of advanced centrifuges, deployable in the future at a clandestine enrichment plant or during a breakout at declared sites. Another risk is that Iran will establish additional centrifuge manufacturing sites unknown to the IAEA. Iran has proven its ability to secretly move manufacturing equipment to new, undeclared sites, further complicating any future verification effort and contributing to uncertainty about where Iran manufactures centrifuges.

  • During the reporting period, the IAEA pressed Iran on obtaining its commitment to implement the non-voluntary Modified Code 3.1 to its CSA. Iran’s ongoing refusal raises doubts about whether Iran will report the construction of a new nuclear facility, such as an enrichment plant, or provide design information to the IAEA as soon as it decides to construct such a facility. The IAEA is concerned since Iran has mentioned a desire to build new nuclear facilities. Iran is building a new facility in the mountains near Natanz that is deeply buried and could be a potential site for a new enrichment plant. Iran told the IAEA that “design information for any new facilities…will be provided in due time.” The IAEA acknowledged that Iran “was no longer prepared to work with the Agency to find a mutually acceptable solution” regarding implementation of Modified Code 3.1.

  • The IAEA concludes that “Iran’s decision to remove all of the Agency’s equipment previously installed in Iran for JCPOA-related surveillance and monitoring activities in relation to the JCPOA has [had] detrimental implications for the Agency’s ability to provide assurance of the peaceful nature of Iran’s nuclear programme.”

  • Concern about Iran’s installation of advanced centrifuges at an undeclared site increases as the 60 percent HEU stocks grow. Such a scenario is becoming more worrisome and viable, since a relatively small number of advanced centrifuge cascades would suffice for the rapid enrichment of the 60 percent HEU to weapon-grade. This hybrid strategy involves the diversion of safeguarded HEU and the secret manufacture and deployment of only three or four cascades of advanced centrifuges. With greater uncertainty about the number of advanced centrifuges Iran is making, there is a greater chance of Iran hiding away the requisite number of advanced centrifuges to realize this scenario.

  • The IAEA reports in its NPT report that the Director General “is seriously concerned that Iran appears to have ‘frozen’ the implementation of the Joint Statement of 4 March 2023 for the past two reporting periods, and questions Iran’s continued commitment to its implementation.” Atomic Energy Organization of Iran (AEOI) chief, Mohammad Eslami, told the IAEA not to expect any new cooperation, particularly on JCPOA-related measures, while sanctions on Iran remain in effect.

  • Combined with Iran’s refusal to resolve outstanding safeguards violations, the IAEA has a significantly reduced ability to monitor Iran’s complex and growing nuclear program, which notably has unresolved nuclear weapons dimensions. The IAEA’s ability to detect diversion of nuclear materials, equipment, and other capabilities to undeclared facilities remains greatly diminished.

Read the full report here.

1. Andrea Stricker is deputy director of the Foundation for Defense of Democracies’ (FDD) Nonproliferation and Biodefense Program and an FDD research fellow.

2. Laurence Norman, “Iran Maintains Steady Expansion of Nuclear Program,” The Wall Street Journal, November 15, 2023,

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