Cascade Interconnection Change at Fordow: Verification and Monitoring in the Islamic Republic of Iran in Light of United Nations Security Council Resolution 2231 (2015) (GOV/INF/2023/1)

February 1, 2023

Weapon Program: 

  • Nuclear

1. This report of the Director General to the Board of Governors and, in parallel, to the United Nations Security Council (Security Council), is on the Islamic Republic of Iran’s (Iran’s) implementation of its nuclear-related commitments under the Joint Comprehensive Plan of Action (JCPOA) in relation to its enrichment-related activities. It provides an update on developments since the Director General’s previous reports.

A. Activities Related to Enrichment at FFEP

A.1. Background

2. As previously reported, in November 2022, Iran described to the Agency in an updated design information questionnaire (DIQ) a new mode of operation for the two IR-6 cascades installed at the Fordow Fuel Enrichment Plant (FFEP), in addition to those previously declared, for the production of UF6 enriched up to 60% U-235. Whereas the two IR-6 cascades had previously operated as individual cascades, they could now operate as a set of two interconnected cascades. On 22 November 2022, the Agency verified at FFEP that Iran was using the two IR-6 cascades (each of 166 IR-6 centrifuges) configured as one set of two interconnected cascades to enrich uranium up to 60% U-235 using UF6 enriched up to 5% U-235 as feed material.

A.2. Recent developments

3. Since 22 November 2022, the Agency has had regular access to FFEP and continued to monitor and verify Iran’s enrichment-related activities at the facility.

4. On 21 January 2023, during a routine inspection without advance notification – also known as unannounced inspection (UI) – at FFEP, the Agency detected that, while the two IR-6 cascades were still being fed with UF6 enriched up to 5% U-235 to produce UF6 enriched up to 60% U-235, they were interconnected in a way that was substantially different from the mode of operation declared by Iran in the most recently updated DIQ (see paragraph 2 above). Subsequently, Iran informed the Agency that it had switched to this mode of operation on 16 January 2023, following the Agency’s previous UI at FFEP earlier the same day.

5. In a letter dated 23 January 2023, the Agency informed Iran that its failure to declare the change it had made to the interconnection of the two IR-6 cascades in advance of implementing the change was inconsistent with Iran’s obligations under Article 45 of its Safeguards Agreement. The Agency again reiterated that any change to facility design and operational modes needed to be declared to the Agency prior to any implementation and requested Iran to provide an updated DIQ for FFEP.

6. On 25 January 2023, the Agency conducted a design information examination (DIE) and a design information verification (DIV) at FFEP at which Iran provided an updated DIQ that reflected the new mode of operation.

B. Safeguards Approaches

7. As indicated above (paragraph 5), the Agency has again reiterated to Iran that it is obliged under the Safeguards Agreement to inform the Agency sufficiently in advance of any change in design information of the facility, including its operational modes, prior to the implementation of such changes, for the Agency safeguards procedures to be adjusted accordingly to ensure effective verification.

8. As previously reported, the Agency informed Iran on 25 November 2022 of its intention to increase the frequency and intensity of its verification activities at FFEP in accordance with the Safeguards Agreement and subsequently held discussions with Iran for this purpose. 

9. Since the Director General’s previous report, the Agency and Iran have continued their discussions. The Agency has increased the frequency and intensity of its verification activities at FFEP. However, some other safeguards measures are still required and are being discussed with Iran.

C. Summary

10. The Director General is concerned that Iran has implemented a substantial change in the design information of FFEP in relation to the production of high enriched uranium without informing the Agency in advance. This is inconsistent with Iran’s obligations under its Safeguards Agreement and undermines the Agency’s ability to adjust the safeguards approach for FFEP and implement effective safeguards measures at this facility.