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20 November 2014

How big is 190,000 SWU? Khamenei's demand examined

On 7 October, Iran’s Supreme Leader Khamenei released on his personal website an 11-point list of demands relating to the current nuclear negotiations with the P5+1 countries.

iran flag

One of Khamenei’s demands – and a clear sticking point in the current negotiations – relates to Iran’s long-term uranium enrichment capability. Khamenei wants Iran to be permitted to have 190,000 separative work units, or SWUs, of uranium enrichment capacity. (A SWU measures uranium enrichment efficiency – Iran’s mainstay IR-1 centrifuge has a SWU capacity of about one; its advanced centrifuges supposedly have much higher separative capacities.) Iran’s centrifuge enrichment facilities at Natanz and Fordow have a combined current capacity of about 24,000 SWU.1

So why 190,000 SWU? Iranian officials state that it so Iran can provide its own nuclear fuel for the Bushehr Power Plant, once the contract for Russia to do so expires in the year 2021. (UPDATE: on 24 November, Iran’s nuclear head Ali Akbar Salehi stated that Iran will need 190,000 SWU of enrichment capacity “within the next eight years.”)

Experts like Mark Hibbs assess that for Iran to provide fuel for Bushehr, an enrichment capacity of about 100,000 SWU per year is required.

This makes 190,000 an odd number. If it is based only on requirements for Bushehr, then it is clearly too high. And Iran’s planned IR-40 reactor is estimated to require only about another 1170 to 2340 SWU for its annual fuelling, depending on how it is ultimately configured.

If Khamenei’s figure is based on broader nuclear power aspirations, like those voiced by Iranian officials who have spoken of a future network of between five and  20 nuclear power reactors, then it is much too low.

Ultimately, Khamenei may be staking out a position that he expects to be whittled down during the course of negotiations. Or there may be other factors at play: perhaps Iran is worried about Russian fuel supply reliability, or something else entirely.

Regardless, by global standards, an enrichment capacity of 190,000 SWU is actually very small. The following graphic shows how this capacity would compare to other enrichment programmes as they are estimated to look in the year 2020:


1 Based on number of installed centrifuges as of August 2014 according to the IAEA. This total SWU figure for Natanz and Fordow assumes that an IR-1 centrifuge has a SWU of one, and that Iran’s advanced centrifuges (IR-2M, IR-4, etc) each have a SWU of 4.

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