You are currently viewing Imagery Update: Construction is Ongoing at the Natanz Tunnel Facility

Imagery Update: Construction is Ongoing at the Natanz Tunnel Facility

Satellite imagery taken between October 25, 2022 and January 15, 2024, indicates continued construction and excavation activities at the tunnel complex under Mt. Kolang Gaz La, where Kolang translates to “pickaxe”. The site is slated to hold a new, large, advanced centrifuge assembly facility that replaces the Iranian Centrifuge Assembly Center (ICAC) destroyed in an attack in July 2020. 

This report is an imagery update from earlier reports on the construction of a new Iranian centrifuge assembly facility, to be buried deep under Kolang Gaz La mountain, located south of the Natanz Fuel Enrichment Plant. Commercial satellite imagery acquired over the last year and a half shows that three years after excavation commenced for the new tunnel facility in the fall of 2020, construction is still ongoing. While the four tunnel entrances were largely complete as of October 2022, the main Western tunnel entrance continued to be strengthened and reinforced, and security structures were added around the site, signs of continuous efforts by Iran to increase the hardness and survivability of the site.

A January 2022 Institute analysis found that the new complex will likely be more deeply buried than the Fordow enrichment plant and have significantly more floor space, raising questions about other sensitive nuclear activities at the site, most worrisome, enrichment activities. In particular, will this site house a gas centrifuge facility?2 

  • Under the subsidiary arrangements to Iran’s comprehensive safeguards agreement (CSA), modified Code 3.1 requires Iran to provide the IAEA with notification and early design information when it has taken a decision to build a new nuclear facility or authorize its construction. However, in February 2021, Iran notified the IAEA that Iran will no longer abide by the code