Analysis of IAEA Iran Verification and Monitoring Report - February 2023

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

March 3, 2023

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  • This report summarizes and assesses information in the International Atomic Energy Agency’s (IAEA) quarterly report for February 28, 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).


  • Iran can now break out and produce enough weapon-grade enriched uranium for a nuclear weapon in 12 days, using only three advanced centrifuge cascades and half of its existing stock of 60 percent enriched uranium. This breakout could be difficult for inspectors to detect promptly, if Iran took steps to delay inspectors’ access.

  • Using its remaining stock of 60 percent enriched uranium and its stock of near 20 percent enriched uranium, Iran could produce enough weapon-grade uranium for an additional four nuclear weapons in a month. During the next two months, Iran could produce two more weapons’ worth of weapon-grade uranium from its stock of less than five percent enriched uranium, meaning that Iran could produce enough weapon-grade uranium for five nuclear weapons in one month and seven in three months.

  • The IAEA detected uranium particles enriched to 83.7 percent from environmental sampling taken during a monthly interim verification (IIV) at the Fordow Fuel Enrichment Plant (FFEP) on January 22. Iran’s answers about this anomaly did not satisfy the IAEA, which has continued probing Iran for more credible answers.

  • The IAEA took the environmental samples that detected the presence of near-84 percent enriched uranium a day after inspectors detected an undeclared interconnection between two IR-6 cascades at Fordow, which Iran should have informed the IAEA about under its safeguards obligations. That change likely led the IAEA to take environmental samples at the product sampling point.

  • This development amplifies concerns that Iran is undertaking covert experiments that add to its ability to more rapidly break out. Worrisome possibilities include that Iran tested a way to produce near weapon-grade uranium without IAEA detection, or to syphon off a small amount of near 84 percent enriched uranium.

  • If the high enrichment level was unintentional, as Iran claims, Iran should have reported the unprecedented enrichment level following the interconnection of the two IR-6 cascades, in line with its reporting of previous fluctuations in the enrichment levels encountered by Iran with the advanced centrifuge cascades dedicated to enriching to 60 percent at the pilot plant. If Iran did not know that the enrichment level reached almost 84 percent, it appears to be operating cascades in a dangerous way, somewhat oblivious to criticality concerns.

  • The IAEA seeks increased access to the FFEP. It reports, “At a technical meeting between senior officials in Tehran on 23 February 2023, Iran confirmed that it would facilitate the notified further increase of the frequency and intensity of Agency verification activities at FFEP.”

  • As of February 12, Iran had a stock of 87.5 kg (an increase of 25.2 kg) (in uranium mass or U mass) of 60 percent enriched uranium in uranium hexafluoride (UF6) form, or 129.4 kg (in hexafluoride mass or hex mass). Adding to concerns about the purpose of this enriched uranium, Iran has converted only 2 kg of 60 percent highly enriched uranium (HEU)(U mass) into a chemical form typically used in civilian nuclear programs and none has been converted since March 2022. Iran keeps the majority (80 percent) of its stock of 60 percent HEU at the Esfahan site, where it maintains a capability to make enriched uranium metal.

  • Iran’s average production rate of 60 percent enriched uranium has doubled to 8 kg per month (U mass) since Iran began on November 22, 2022 to enrich uranium to near 60 percent in two IR-6 centrifuge cascades at the FFEP, in addition to the two cascades, one containing IR-6 centrifuges and the other IR-4 centrifuges, at the Natanz Pilot Fuel Enrichment Plant (PFEP). In both cases, Iran uses up to 5 percent low enriched uranium (LEU) as feed.

  • The average production rate of 20 percent enriched uranium at the FFEP decreased by half from 26.8 kg (U mass) or 39.6 kg (hex mass) per month, to 13 kg (U mass) or 19.2 kg (hex mass) per month.

  • As of February 12, 2023, Iran had an IAEA-estimated stock of 434.7 kg of 20 percent enriched uranium (U mass and in the form of UF6), equivalent to 643 kg (hex mass). Iran also had a stock of 37.7 kg (U mass) of 20 percent uranium in other chemical forms.

  • At the Natanz Fuel Enrichment Plant (FEP), Iran added seven cascades of advanced centrifuges during the last reporting period, for a total installed of 36 cascades of IR-1 centrifuges, 21 cascades of IR-2m centrifuges (up by six), four cascades of IR-4 centrifuges (up by one), and three cascades of IR-6 centrifuges.

  • During the last six months, Iran installed 15 IR-2m centrifuge cascades at the FEP, or roughly 3,650 centrifuges. It is not clear whether these are newly made centrifuges or those taken from storage.

  • Iran’s current, total operating enrichment capability is estimated to be about 18,700 separative work units (SWU) per year, higher than the 16,300 SWU per year at the end of the last reporting period. As of the end of this reporting period, Iran was not yet using its fully installed enrichment capacity at the FEP, which, as noted above, has grown substantially.

  • Average production of near 5 percent LEU at the FEP decreased, but for the second time in a row since early 2021, Iran’s near 5 percent LEU stock increased from one reporting period to the next, reaching 1324.5 kg (U mass).

  • Despite the increase, during this reporting period, in the amount of uranium enriched between two and five percent, Iran has not prioritized stockpiling of this material, during the last two years. This is at odds with its 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 any of Iran’s civilian needs.

  • Iran’s overall reported stockpile of enriched uranium increased by 87.1 kg (U mass).

  • The IAEA discussed a discrepancy in Iran’s natural uranium inventory at the Uranium Conversion Facility (UCF). The Wall Street Journal reported that the discrepancy may be related to inspectors’ efforts to locate undeclared uranium Iran used during its early-2000s nuclear weapons program, in which case the IAEA’s upcoming Nuclear Non-Proliferation Treaty (NPT) safeguards report may contain more relevant information.

  • The IAEA reports that it can no longer reestablish continuity of knowledge about Iran’s activities under a revived JCPOA, such as production of advanced centrifuges and heavy water, due to Iran’s decision in February 2021 to deny the IAEA access to data from key JCPOA-related monitoring and surveillance equipment and Iran’s decision in June 2022 to remove all such equipment, including video cameras and online enrichment monitors. The IAEA says it would need to establish a new baseline altogether and would require access to extensive records. It reports, “Any future baseline for [JCPOA] verification and monitoring activities would take a considerable time to establish and would have a significant degree of uncertainty.”

  • 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 is fully capable of moving manufacturing equipment to new, undeclared sites, further complicating any future verification effort and contributing to uncertainty about where Iran manufactures centrifuges.

  • The IAEA concludes that “Iran’s decision to remove all of the Agency’s equipment previously installed in Iran for 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.”

  • 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.

  • Concern about Iran’s installation of advanced centrifuges at an undeclared site is magnified as its 60 percent HEU stocks grow. Such a scenario becomes more worrisome and viable, since it requires a relatively small number of advanced centrifuge cascades to rapidly enrich the 60 percent material to weapon-grade. This hybrid strategy involves the diversion of safeguarded HEU and the secret manufacture and deployment of only two or three 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.

Read the full analysis as PDF here.

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

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