3. Uranium 3.1 Description Iran’s current enrichment program consists of nearly 18,500 first generation IR-1 centrifuges (approximately 15,500 installed at Natanz and 3,000 installed at Fordow) and another 1,000 more-advanced IR-2 centrifuges at Natanz, for a total of about 19,500 centrifuges, with an additional nearly 400 more-advanced centrifuge machines undergoing various tests and experimentation at the Pilot Fuel Enrichment Plant at Natanz. Of the total, approximately 9,200 IR-1 centrifuges at Natanz and 700 IR-1 centrifuges at Fordow are actually enriching uranium.7 Iran’s current stockpile of enriched uranium includes about 7.6 tons of low-enriched uranium (up to 3.67% U-235) in the form of UF6, and about 2.4 tons of low-enriched uranium (LEU) in the form of oxide (or being converted to oxide). None of Iran’s near 20% enriched uranium remains in the form of UF6, but it retains about 230 kilograms of near 20% enriched uranium oxide.8 The JCPOA includes a detailed set of physical limits on numbers and types of centrifuges, centrifuge research and development, centrifuge manufacturing, locations and levels of enrichment, and stocks of enriched uranium. The physical limits phase out over 10 to 15 years (see Figure 6). 7
Enrichment is a process to increase the concentration of U-235 relative to U-238. In natural uranium, the U-235 concentration is 0.7%. Low-enriched uranium is typically used for fuel for light water power reactors. Depending on their design, research reactors can be fueled with natural uranium, low enriched uranium, nearly 20% U-235, or even highly enriched uranium (about 90% U-235). Typically, nuclear weapons use highly enriched uranium.
8
The oxide is either in powder form, in the process of conversion to oxide, or has been used to fabricate fuel for the Tehran Research Reactor.
Belfer Center for Science and International Affairs | Harvard Kennedy School
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