Qualla: IR-40

IR-40: Introduction

Sat, 28 Feb 2026 00:00:00 GMT

Photo credit Nanking2012, CC BY-SA 3.0. In January 2016, Iran announced it had poured concrete into the core of its heavy water reactor near Arak. Three years later, the head of Iran's Atomic Energy Organization went on national television and said the photographs of that concrete pour had been doctored -- and that Iran had secretly purchased replacement parts. Whether bluff or revelation, the claim captured everything the IR-40 reactor had become: less a functioning nuclear facility than a vessel for competing narratives about trust, verification, and the distance between a research tool and a weapon.

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Image: Nanking2012 | CC BY-SA 3.0

IR-40: From Tehran's Suburbs to the Arak Plain

Sat, 28 Feb 2026 00:00:00 GMT

Photo credit Nanking2012, CC BY-SA 3.0. The reactor's origins trace to a practical problem. By the mid-1980s, Iran's leadership wanted a nuclear power plant that could run on natural uranium, avoiding the need for enrichment to produce fuel. Heavy water would serve as both moderator and coolant. The design was 90 perce...

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Image: Nanking2012 | CC BY-SA 3.0

IR-40: The Plutonium Question

Sat, 28 Feb 2026 00:00:00 GMT

Photo credit 1379meraj, CC BY-SA 4.0. What made the IR-40 a flashpoint was not what it was designed to do but what it could do. Natural-uranium-fueled heavy water reactors were originally developed to produce weapons-grade plutonium. Analysis suggested that at full operation, the IR-40 could yield 8 to 10 kilograms o...

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Image: 1379meraj | CC BY-SA 4.0

IR-40: A Deal, a Core, and Contested Concrete

Sat, 28 Feb 2026 00:00:00 GMT

Photo credit Nanking2010, Public domain. The 2015 Joint Comprehensive Plan of Action, negotiated between Iran and the P5+1 nations, addressed the IR-40 directly. Iran agreed to redesign the reactor with international assistance to minimize plutonium production, remove the existing core or calandria and fill it with conc...

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Image: Nanking2010 | Public domain

IR-40: Under Fire

Sat, 28 Feb 2026 00:00:00 GMT

Photo credit Nanking2012, CC BY-SA 3.0. In June 2025, during the Iran-Israel war, Israeli forces struck the reactor complex directly. The containment building sustained damage from a direct hit, and distillation towers at the adjacent heavy water production plant were also struck. Israel had warned residents of Arak an...

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Image: Nanking2012 | CC BY-SA 3.0